U.S. patent application number 16/544180 was filed with the patent office on 2020-02-20 for method and kits for identifying of cdk9 inhibitors for the treatment of cancer.
This patent application is currently assigned to Memorial Sloan-Kettering Cancer Center. The applicant listed for this patent is Memorial Sloan-Kettering Cancer Center, St. Jude Children's Research Hospital. Invention is credited to Chun-Hao HUANG, Scott William LOWE, Amaia LUJAMBIO, Charles J. SHERR.
Application Number | 20200054640 16/544180 |
Document ID | / |
Family ID | 54241285 |
Filed Date | 2020-02-20 |
![](/patent/app/20200054640/US20200054640A1-20200220-D00000.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00001.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00002.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00003.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00004.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00005.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00006.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00007.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00008.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00009.png)
![](/patent/app/20200054640/US20200054640A1-20200220-D00010.png)
View All Diagrams
United States Patent
Application |
20200054640 |
Kind Code |
A1 |
LOWE; Scott William ; et
al. |
February 20, 2020 |
METHOD AND KITS FOR IDENTIFYING OF CDK9 INHIBITORS FOR THE
TREATMENT OF CANCER
Abstract
A method of determining sensitivity to cancer treatment includes
the step of determining the presence of overexpression of MYC in a
biological sample from a patient suffering from cancer, wherein the
presence of overexpression of MYC indicates a sensitivity to a
treatment by a CDK9 inhibitor and wherein the cancer is selected
from the group consisting of carcinoma, leukemia, and lymphoma.
Inventors: |
LOWE; Scott William; (New
York City, NY) ; SHERR; Charles J.; (Memphis, TN)
; HUANG; Chun-Hao; (New York City, NY) ; LUJAMBIO;
Amaia; (New York City, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Memorial Sloan-Kettering Cancer Center
St. Jude Children's Research Hospital |
New York City
Memphis |
NY
TN |
US
US |
|
|
Assignee: |
Memorial Sloan-Kettering Cancer
Center
St. Jude Children's Research Hospital
|
Family ID: |
54241285 |
Appl. No.: |
16/544180 |
Filed: |
August 19, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15301683 |
Oct 3, 2016 |
10383873 |
|
|
PCT/US2015/024057 |
Apr 2, 2015 |
|
|
|
16544180 |
|
|
|
|
61975401 |
Apr 4, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 33/57438 20130101;
A61K 31/655 20130101; G01N 2333/91205 20130101; G01N 2800/52
20130101; A61K 31/4545 20130101; A61K 31/44 20130101; G01N 33/57423
20130101; C12N 15/1137 20130101; C12Q 2600/106 20130101; A61K
31/445 20130101; A61K 45/06 20130101; C12N 2320/30 20130101; A61K
31/40 20130101; A61K 31/519 20130101; G01N 33/57426 20130101; C12N
2320/10 20130101; C12Y 207/11023 20130101; C12Q 1/6886 20130101;
A61K 31/7048 20130101; A61K 31/404 20130101; C12N 2310/531
20130101; C12Q 2600/158 20130101; C12Y 207/11022 20130101; A61K
31/4745 20130101; A61K 31/7068 20130101; A61K 31/7048 20130101;
A61K 2300/00 20130101; A61K 31/7068 20130101; A61K 2300/00
20130101; A61K 31/655 20130101; A61K 2300/00 20130101; A61K 31/44
20130101; A61K 2300/00 20130101; A61K 31/40 20130101; A61K 2300/00
20130101; A61K 31/4745 20130101; A61K 2300/00 20130101; A61K 31/404
20130101; A61K 2300/00 20130101; A61K 31/4545 20130101; A61K
2300/00 20130101; A61K 31/519 20130101; A61K 2300/00 20130101; A61K
31/445 20130101; A61K 2300/00 20130101 |
International
Class: |
A61K 31/519 20060101
A61K031/519; C12Q 1/6886 20060101 C12Q001/6886; A61K 31/7048
20060101 A61K031/7048; A61K 31/655 20060101 A61K031/655; A61K
31/4745 20060101 A61K031/4745; A61K 31/4545 20060101 A61K031/4545;
C12N 15/113 20060101 C12N015/113; G01N 33/574 20060101 G01N033/574;
A61K 45/06 20060101 A61K045/06; A61K 31/7068 20060101 A61K031/7068;
A61K 31/445 20060101 A61K031/445; A61K 31/44 20060101 A61K031/44;
A61K 31/404 20060101 A61K031/404; A61K 31/40 20060101
A61K031/40 |
Claims
1. A method of determining sensitivity to cancer treatment in a
patient suffering from cancer, the method comprising the steps of:
determining the presence of overexpression of MYC in a biological
sample from the patient, wherein the presence of overexpression of
MYC indicates a sensitivity to a treatment by a CDK9 inhibitor,
wherein the cancer is selected from the group consisting of
carcinoma, leukemia, and lymphoma.
2. The method of claim 1, wherein the cancer is hepatocellular
carcinoma.
3. The method of claim 1, wherein the cancer is non-small cell lung
carcinoma.
4. The method of claim 1, further comprising the step of
administering an effective amount of the CDK9 inhibitor into the
patient if a overexpression of MYC is found in the biological
sample.
5. The method of claim 4, wherein the CDK9 inhibitor is PHA 767491,
PHA-793887, PHA-848125, BAY 1143572, BAY 1112054, Cdk9 inhibitor II
(CAS 140651-18-9 from Calbiochem), DRB, AZD-5438, SNS-032,
dinaciclib, LY2857785, flavopiridol, purvalanol B, CDKI-71,
CDKI-73, CAN508, FIT-039, CYC065,
3,4-dimethyl-5-[2-(4-piperazin-1-yl-phenylamino)-pyrimidin-4-yl]--
3H-thiazol-2-one, wogonin, apigenin, chrysin, luteolin,
4-methyl-5-[2-(3-nitroanilino)pyrimidin-4-yl]-1,3-thiazol-2-amine,
shRNAs against CDK9, anti-sense mRNA against CDK9 and anti-CDK9
antibodies.
6. A method of evaluating the efficacy of administering CDK9
inhibitors in a patient suffering from cancer, the method
comprising the steps of: determining the presence in a biological
sample from the patient of suppressed levels of phosphorylation of
Ser2 on the C-terminal repeat domain (CTD) of RNA Pol II, wherein
the presence of suppressed levels of phosphorylation of Ser2 on the
CTD of RNA Pol II is indicative that CDK9 is being inhibited in the
patient, wherein the cancer is selected from the group consisting
of carcinoma, leukemia, and lymphoma.
7. The method of claim 6, wherein the cancer is hepatocellular
carcinoma.
8. The method of claim 6 wherein the cancer is non-small cell lung
carcinoma.
9-15. (canceled)
16. A kit for determining sensitivity to a CDK9 inhibitor in a
cancer patient, comprising: (1) one or more synthetic
oligonucleotides that specifically hybridizes to a human MYC RNA or
(2) one or more antibodies that specifically bind to a human MYC
protein; and one or more reagents for processing a biological
sample to obtain nucleotide molecules or proteins, wherein the
patient is suffering from a carcinoma, leukemia or lymphoma.
17. The kit of claim 16, further comprising reagents for RNA
purification or protein purification.
18. The kit of claim 16 or 17, further comprising one or more
reagents for determining levels of phosphorylation of Ser2 on the
C-terminal repeat domain (CTD) of RNA Pol II.
19. A kit for evaluating the efficacy of administering CDK9
inhibitors in a patient suffering from cancer, comprising: One or
more reagents for determining a level of phosphorylation of Ser2 on
the C-terminal repeat domain (CTD) of RNA Pol II in a biological
sample from the patient, one or more reagents for processing the
biological sample to obtain proteins from the sample, wherein the
cancer is selected from the group consisting of carcinoma,
leukemia, and lymphoma.
Description
[0001] This application claims the priority of U.S. Provisional
Application Ser. No. 61/975,401, filed on Apr. 4, 2014.
FIELD
[0002] The present application generally relates to methods of
treatment for cancer using CDK9 inhibitors and the detection of
biomarkers relating to drug-resistant tumors.
BACKGROUND
[0003] Hepatocellular carcinoma (HCC) is the third leading cause of
cancer-related mortality worldwide. A major risk factor for HCC,
the most common type of primary liver cancer, is cirrhosis,
frequently caused by chronic viral hepatitis, alcohol abuse, and
nonalcoholic fatty liver disease. Although treatment of HCC has
greatly improved over the last decades, most HCC patients diagnosed
at advanced stages are ineligible for curative ablative therapies
such as liver resection or transplantation. The use of the
multikinase inhibitor sorafenib in patients with advanced HCC
suggests that targeted therapies could be beneficial in this
cancer; however, this regimen only extends life expectancy from 8
to 11 months, highlighting the urgent need for new therapeutic
approaches.
[0004] Recent developments in gene-expression profiling
technologies have enabled the molecular classification of HCCs into
defined subclasses, creating a solid foundation on which to build
more informative clinical trials. Furthermore, exhaustive genomic
studies have identified MYC genomic amplifications, .beta.-catenin
mutations, and tumor suppressor TP53 inactivation as frequent
events in HCC. However, unlike other tumor types, which present
genetic drivers that can be therapeutically exploited, such as EGFR
mutations in lung cancer and BRAF mutations in melanoma, HCC is
genetically heterogeneous and lacks clearly targetable genetic
drivers. Thus, it seems likely that more insights into the function
of currently "undruggable" genetic lesions will be necessary to
develop rational therapies for this disease.
SUMMARY
[0005] One aspect of the present application relates to a method of
determining sensitivity to cancer treatment in a patient suffering
from cancer. The method comprises the steps of: determining the
presence of overexpression of MYC in a biological sample from the
patient, wherein the presence of overexpression of MYC indicates a
sensitivity to a treatment by a CDK9 inhibitor, wherein the cancer
is selected from the group consisting of carcinoma, leukemia, and
lymphoma.
[0006] Another aspect of the present application relates to a
method of treating a patient suffering from cancer. The method
comprises the steps of: determining the overexpression of MYC in a
biological sample from the patient; and administering to the
patient an effective amount of a CDK9 inhibitor, if overexpression
of MYC is present in the biological sample, wherein the cancer is
selected from the group consisting of carcinoma, leukemia, and
lymphoma.
[0007] Another aspect of the present application relates to a
method of evaluating the efficacy of administering CDK9 inhibitors
in a patient suffering from cancer. The method comprises the steps
of: determining the presence in a biological sample from the
patient of suppressed levels of phosphorylation of Ser2 on the
C-terminal repeat domain (CTD) of RNA Pol II, where the presence of
suppressed levels of phosphorylation of Ser2 in the CTD of RNA Pol
II is indicative that CDK9 is being inhibited in the patient,
wherein the cancer is selected from the group consisting of
carcinoma, leukemia and lymphoma.
[0008] Another aspect of the present application relates to a kit
for evaluating the efficacy of administering CDK9 inhibitors in a
patient suffering from cancer. The kit comprises one or more
reagents for determining a level of phosphorylation of Ser2 on the
C-terminal repeat domain (CTD) of RNA Pol II in a biological sample
from the patient, one or more reagents for processing the
biological sample to obtain proteins from the sample, wherein the
cancer is selected from the group consisting of carcinoma, leukemia
and lymphoma.
[0009] Another aspect of the present application relates to a kit
for determining the sensitivity to a CDK9 inhibitor in a cancer
patient. The kit comprises (1) one or more synthetic
oligonucleotides that specifically hybridizes to a human MYC RNA or
(2) one or more antibodies that specifically bind to a human MYC
protein; and one or more reagents for processing a biological
sample to obtain nucleotide molecules or proteins, wherein the
patient is suffering from a carcinoma, leukemia or lymphoma.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 shows RNAi screen for genes encoding known drug
targets. (FIG. 1A) Library features and schematic of the TRMPV-neo
vector. TRE, tetracycline regulated element. (FIG. 1B) Pathway
categories of "drug target" genes included in the library. Numbers
indicate the number of genes in each category. (FIG. 1C) RNAi
screening strategy. (FIG. 1D) Representative scatter plots
illustrating the correlation of normalized reads per shRNA between
replicates at the beginning of the experiment (left) and replicates
at different time points (right). (FIG. 1E) Pooled
negative-selection screening results in MP1 murine HCC cells. shRNA
abundance ratios of 2046 shRNAs were calculated as the number of
normalized reads after 12 days of culture on doxycycline (T12)
divided by the number of normalized reads before doxycycline
treatment (T0), and plotted as the mean of three replicates in
ascending order. MP1, Myc;p53-/- clone 1 murine HCC cells; T0, cell
population at the beginning of the experiment; T12, cell population
at the end of the experiment, at day 12; dox, doxycycline; r,
Pearson correlation coefficient.
[0011] FIG. 2 shows that CDK9 is required for the proliferation of
some HCC cell lines. (FIG. 2A) Competitive proliferation assay.
G418-selected Venus+cells were mixed with untransduced cells at 1:1
ratio, and subsequently cultured in the presence of doxycycline.
The percentage of Venus.sup.+dsRed.sup.+ (shRNA-expressing) cells
was determined at different time points (results at day 0 and day
14 are shown and are relative to day 0). Changes were used as
readout of growth inhibitory effects. Values are mean.+-.SD of
three independent replicates. The graphs show the validation of the
candidate shRNAs as well as control shRNAs (Ren.713; Myc.1891 and
Rpa3.561) in MP1 murine HCC cells. (FIG. 2B) Immunoblots showing
the knockdown induced by shRNAs expressed from TRMPV-neo in MP1
murine HCC cells. .beta.-actin was used as loading control. (FIG.
2C) Competitive proliferation assay of control and candidate shRNAs
expressed from TRMPV-neo in immortalized MEFS (iMEFs), as described
in FIG. 2A. (FIG. 2D) Immunoblots showing the knockdown induced by
shRNAs expressed from TRMPV-neo in iMEFs. .beta.-actin was used as
loading control. (FIGS. 2E and 2F) Competitive proliferation assay
of control (Renilla and MYC) and CDK9 shRNAs expressed from
TRMPV-neo-miR-E (FIG. 2E) or TRMPV-neo (FIG. 2F) in different
murine (FIG. 2E) and human cell lines (FIG. 2F), as described in
FIG. 2A. The percentage of shRNA-expressing cells at day 14
relative to day 0 is shown. MP1, Myc;p53-/- murine HCC clone #1
cells; The "E" letter after the name of the shRNA indicates that
the shRNA is cloned into miR-E backbone instead of miR-30.
[0012] FIG. 3 shows pharmacological inhibition of CDK9 in HCC cell
lines. (FIG. 3A) Scatter plot illustrating the correlation between
anti-proliferative effects of CDK9 shRNAs and the IC50 of
PHA-767491 in six human cell lines. The correlation and p values of
three additional CDK9 inhibitors and one DNA replication inhibitor
(aphidicolin) are also shown in the right panel. The survival is
defined as the average of the survival ratio of two shRNAs in
competitive proliferation assay. (FIG. 3B) Proliferation rates of
PHA-767491-treated human cells, calculated by measuring the change
in viable cell number after 72 h in culture and fitting data to an
exponential growth curve. Results were normalized to the
proliferation rate of vehicle (H2O) treated cells, set to 1. Values
are mean+/-SD of three independent replicates. (FIG. 3C) Summary of
PHA-767491 IC50 values of human cell lines in FIG. 3A. (FIG. 3D)
Scatter plot illustrating the correlation between survival with
CCNT1 shRNAs and survival with CDK9 (black), in murine and human
cell lines. (FIG. 3E) Representative flow cytometry plots showing
cell cycle analysis (BrdU+7-AAD+ double staining) of cells after 48
hours of PHA-767491 treatment. The experiment was performed twice
and values indicate the mean.+-.SD. r, Pearson correlation
coefficient; FLV, flavopiridol; PHA, PHA-767491; SNS, SNS-032;
APHI, aphidicolin.
[0013] FIG. 4 shows that MYC expression predicts response to CDK9
inhibition. (FIG. 4A) Scatter plot illustrating the correlation
between PHA-767491 IC50 values and MYC expression levels in human
HCC (red), leukemia, lymphoma, and lung cancer cell lines (n=28).
(FIG. 4B) Scatter plot illustrating the correlation between
survival with CDK9 shRNAs and MYC expression levels in a panel of
different human HCC cell lines. The survival is defined as the
average of the survival ratio of two shRNAs in competitive
proliferation assay. (FIG. 4C) Immunoblots showing MYC protein
levels in 10 human HCC cell lines. .beta.-actin was used as loading
control. (FIGS. 4D and 4E) GSEA plot evaluating the association
between low IC.sub.50 of PHA-767491 and MYC targets (FIG. 4D) or a
MYC-overexpressing subclass of HCC patients (FIG. 4E). (FIG. 4F)
GO-term analysis of the genes that are significantly associated
with sensitivity to PHA-767401. r, Pearson correlation coefficient;
PHA, PHA-767491; NES, normalized enrichment score; FDR, false
discovery rate.
[0014] FIG. 5 shows that CDK9 mediates transcription elongation of
MYC targets in MYC-overexpressing cancer cells. (FIGS. 5A and 5B)
ChIP-qPCR performed in human HCC cells expressing CDK9 and MYC
shRNAs (FIG. 5A) or treated with PHA-767491 (6 hours at 4.5 .mu.M)
(FIG. 5B) with RNA pol II antibody and primers located either in
the transcription start site (TSS) or in the gene body (GB) of
NPM1. (FIG. 5C) Pausing index of NPM1 in human HCC cell lines. The
pausing index, also known as traveling ratio, is calculated as the
ratio between the RNA pol II bound to the TSS and the RNA pol II
bound to the GB. Color code and statistics as in FIGS. 5A and 5B.
(FIG. 5D) Quantitative RT-PCR of NPM1 in human HCC cell lines
treated with PHA-767491 (16 hours at 4.5 .mu.M) or with CDK9
shRNAs. Data are relative to expression in the untreated cells or
Renilla-shRNA in HepG2 cells, normalized to the average expression
of the housekeeping gene GAPDII. Values are mean.+-.SD from two
independent experiments. Color code and statistics as in FIGS. 5A
and 5B. PHA, PHA-767491. (FIGS. 5E and 5F) PET imaging with
.sup.89Zr-transferrin of HepG2 (E) or Alexander (F) tumors with or
without 3-d treatment with PHA-767491. (L) Liver; (T) tumor;
(trans.) transverse. The hashmark scale for all PET image data
shows radiotracer uptake in units of injected dose per gram (%
ID/g), with diagonal hashmarks sloping left corresponding to the
highest activity, and diagonal hashmarks sloping right
corresponding to the lowest activity.
[0015] FIG. 6 shows that transcription elongation is required to
maintain proliferation in MYC-overexpressing HCC. (FIGS. 6A and 6B)
Scatter plot illustrating the correlation between survival with MYC
shRNAs and with CDK9 shRNAs in mouse and human cell lines (FIG. 6A)
and with CCNT1 shRNAs (B). The survival is defined as the ratio of
surviving cells in the competitive proliferation assays (FIGS. 2E
and 2F). In the case of CDK9 and CCNT1, the average of the survival
of two different shRNAs is used. (FIG. 6C) Immunoblots showing MYC
overexpression effect on Ser2 phosphorylation of RNA Pol II in low
MYC-expressing SNU475 and Alexander cells. .beta.-actin was used as
loading control. Values indicate normalized protein levels,
normalized with .beta.-actin or RNA Pol II, and relative to the
levels in HepG2 cells. (FIG. 6D) Pausing index of NPM1 and BRG1 in
Alexander cells overexpressing MYC. Pausing index, also known as
traveling ratio, is calculated as the ratio between the RNA pol II
bound to the transcription start site and the RNA pol II bound to
the gene body. (FIG. 6E) Quantitative RT-PCR of NPM1 and BRG1 in
Alexander cells overexpressing MYC. Data are relative to expression
in the cells expressing an empty vector, normalized to the average
expression of the housekeeping gene GAPDH. Values are mean.+-.SD
from two independent experiments. (FIG. 6F) Proliferation rates of
PHA-767491-treated cells in FIG. 6C, calculated by measuring the
increase in viable cell number after 72 h in culture and fitting
data to an exponential growth curve. Results are normalized to the
proliferation rate of vehicle (H2O) treated cells, set to 1. Values
are mean.+-.SD of two independent replicates. The IC50 values are
included in .mu.M. (FIG. 6G) Scatter plot illustrating the
correlation between MYC protein levels and the IC50 of PHA-767491
on the different cell lines in FIG. 6F. The "E" letter after the
name of the shRNA indicates that the shRNA is cloned into miR-E
backbone instead of miR-30; PHA, PHA-767491; r, Pearson correlation
coefficient.
[0016] FIG. 7 shows that CDK9 is required for initiation and
maintenance of MYC-overexpressing liver tumors. CDK9 is required
for initiation and maintenance of MYC-overexpressing liver tumors.
(FIG. 7A) Dot plot representation of the number of liver tumors
after the hydrodynamic injection of Myc oncogene and the
corresponding shRNAs. Bars represent the mean.+-.SD of five
independent mice. (FIG. 7B) Representative bright-field and
fluorescent images of the livers in A. Tumors are positive for GFP.
(FIG. 7C) Immunoblots showing the knockdown induced by CDK9 shRNAs
in two representative tumors. CDK9 inhibition leads to a decrease
in the levels of phosphorylation of Ser2 of RNA pol II (pSer2) and
mild changes in total RNA pol II levels (Pol II). .beta.-actin was
used as loading control. (FIG. 7D) Bioluminescent imaging of
representative mice orthotopically transplanted with MP1 HCC cells
harboring the indicated TRMPV-Neo-miR-E shRNAs. Doxycycline was
administered upon disease onset, seven days after transplant. (FIG.
7E) Quantification of bioluminescent imaging responses with or
without doxycycline treatment. Values are mean.+-.SD of six
independent tumors. (FIG. 7F) Quantification of the number of Ki67
positive cells per field, after analyzing three fields per animal,
and three animals per condition. Values are mean.+-.SD. (FIG. 7G)
Immunoblot showing the effects caused by PHA-767491 in two
representative tumors. PHA-767491 treatment leads to a decrease in
the levels of phosphorylation of Ser2 of RNA pol II (pSer2) and
mild changes in total RNA pol II levels (Pol II). .beta.-actin was
used as loading control. (FIG. 7H) Bioluminescent imaging of
representative mice orthotopically transplanted with either HepG2
or Alexander HCC cells. PHA-767491 was administered upon disease
onset (considered as day 0), 28 days after transplant. Days 3 and
24 of treatment are shown. (FIG. 7I) Quantification of
bioluminescent imaging responses with or without PHA-767491
treatment. Values are mean.+-.SD of seven or eight independent
tumors. (FIG. 7J) Quantification of the number of Ki67 positive
cells per field, after analyzing three fields per animal, and three
animals per condition. Values are mean.+-.SD. MP1, Myc;p53-/-
murine HCC clone #1 cells; Dox, doxycycline; The "E" letter after
the name of the shRNA denotes that the shRNA is cloned into miR-E
backbone instead of miR-30; PHA, PHA-767491.
[0017] FIG. 8 shows liver regeneration to reveal the therapeutic
index associated with CDK9 inhibition in vivo. (FIG. 8A) Schematic
representation of the liver regeneration. miRE shRNA transposon
vectors were injected together with CMV-SB13 transposase by
hydrodynamic tail vein injection. Partial hepatectomy was performed
after one week. Liver/body ratio and GFP percentage were examined
after two weeks. (FIG. 8B) CDK9 inhibition does not show
significant impact on liver/body ratio, compared to Ren.713E
(neutral control). shRpa3.561E is used as a positive control. (FIG.
8C) Representative histological analysis of liver, stained for GFP.
(FIG. 8D) CDK9 inhibition does not show significant impact on the
percentage of GFP.sup.+ cells before and after partial
hepatectomy.
[0018] FIG. 9 shows inducible and reversible transgenic RNAi mice
to reveal the therapeutic index associated with CDK9 inhibition in
vivo. (FIG. 9A) Schematic representation of the generation and
application of shRNA transgenic mice. TRE-Driven miRE shRNAs are
targeted to the ColA1 locus to drive doxycycline (dox)-dependent
genes knockdown in ES Cells, embryonic and adult tissues of the
mouse. By using a sensitive and widely expressed rtTA mice strain,
CAGs-rtTA3, GFP-miRE shRNAs can be efficiently expressed in most
tissues to study on-target toxicities. (FIG. 9B) Western blot
analyses of CDK9 and RNAPII pSer2 inhibitions in dox-treated ES
cell clones containing R26-rtTA and Ren.713E (neutral control) or
two CDK9 miRE shRNAs (CDK9.421E and CDK9.1260E). (FIG. 9C)
Systematic knockdown of CDK9 and expression of GFP in most tissues
from CAGs-rtTA3 expressing shRen.713E, shCDK9.421E and shCDK9.1260E
mice, maintained on a dox diet for 2 weeks. (FIG. 9D)
Representative images for CAGs-rtTA3 expressing shRen.713E,
shCDK9.421E and shCDK9.1260E mice after 2-week dox diet are shown.
No significant difference of the appearance between the mice. (FIG.
9E) Mean weight changes (g) of male and female (combined)
CAGs-rtTA3/+; TG-Ren.713E, TG-CDK9.421E and TG-CDK 9.1260E mice on
the dox diet, relative to day 0 of dox treatment. Error bars
represent SEM (n=3).
DETAILED DESCRIPTION
[0019] The following detailed description is presented to enable
any person skilled in the art to use the present methods and kits.
For purposes of explanation, specific nomenclature is set forth to
provide a thorough understanding of the present methods and kits.
However, it will be apparent to one skilled in the art that these
specific details are not required to practice the use of the
methods and kits. Descriptions of specific applications are
provided only as representative examples. The present methods and
kits are not intended to be limited to the embodiments shown, but
is to be accorded the widest possible scope consistent with the
principles and features disclosed herein.
[0020] Headings used herein are for organizational purposes only
and are not meant to be used to limit the scope of the description
or the claims. As used throughout this application, the word "may"
is used in a permissive sense (i.e., meaning having the potential
to), rather than the mandatory sense (i.e., meaning must). The
terms "a" and "an" herein do not denote a limitation of quantity,
but rather denote the presence of at least one of the referenced
items.
[0021] As used herein the term "cancer" refers to any of the
various malignant neoplasms characterized by the proliferation of
cells that have the capability to invade surrounding tissue and/or
metastasize to new colonization sites, including but not limited to
carcinomas, leukemia, lymphoma, sarcomas, melanoma and germ cell
tumors.
[0022] The term "carcinoma" refers to a malignant new growth made
up of epithelial cells tending to infiltrate the surrounding
tissues and give rise to metastases. Exemplary carcinomas include,
for example, acinar carcinoma, acinous carcinoma, adenocystic
carcinoma, adenoid cystic carcinoma, carcinoma adenomatosum,
carcinoma of adrenal cortex, alveolar carcinoma, alveolar cell
carcinoma, basal cell carcinoma, carcinoma basocellulare, basaloid
carcinoma, basosquamous cell carcinoma, bronchioalveolar carcinoma,
bronchiolar carcinoma, bronchogenic carcinoma, cerebriform
carcinoma, cholangiocellular carcinoma, chorionic carcinoma,
colloid carcinoma, comedo carcinoma, corpus carcinoma, cribriform
carcinoma, carcinoma en cuirasse, carcinoma cutaneum, cylindrical
carcinoma, cylindrical cell carcinoma, duct carcinoma, carcinoma
durum, embryonal carcinoma, encephaloid carcinoma, epiennoid
carcinoma, carcinoma epitheliale adenoides, exophytic carcinoma,
carcinoma ex ulcere, carcinoma fibrosum, gelatiniform carcinoma,
gelatinous carcinoma, giant cell carcinoma, carcinoma
gigantocellulare, glandular carcinoma, granulosa cell carcinoma,
hair-matrix carcinoma, hematoid carcinoma, hepatocellular
carcinoma, Hurthle cell carcinoma, hyaline carcinoma, hypemephroid
carcinoma, infantile embryonal carcinoma, carcinoma in situ,
intraepidermal carcinoma, intraepithelial carcinoma, Krompecher's
carcinoma, Kulchitzky-cell carcinoma, large-cell carcinoma,
lenticular carcinoma, carcinoma lenticulare, lipomatous carcinoma,
lymphoepithelial carcinoma, carcinoma medullare, medullary
carcinoma, melanotic carcinoma, carcinoma molle, mucinous
carcinoma, carcinoma muciparum, carcinoma mucocellulare,
mucoepidermoid carcinoma, carcinoma mucosum, mucous carcinoma,
carcinoma myxomatodes, naspharyngeal carcinoma, oat cell carcinoma,
carcinoma ossificans, osteoid carcinoma, papillary carcinoma,
periportal carcinoma, preinvasive carcinoma, prickle cell
carcinoma, pultaceous carcinoma, renal cell carcinoma of kidney,
reserve cell carcinoma, carcinoma sarcomatodes, schneiderian
carcinoma, scirrhous carcinoma, carcinoma scroti, signet-ring cell
carcinoma, carcinoma simplex, small-cell carcinoma, solanoid
carcinoma, spheroidal cell carcinoma, spindle cell carcinoma,
carcinoma spongiosum, squamous carcinoma, squamous cell carcinoma,
string carcinoma, carcinoma telangiectaticum, carcinoma
telangiectodes, transitional cell carcinoma, carcinoma tuberosum,
tuberous carcinoma, verrucous carcinoma, and carcinoma
villosum.
[0023] The term "leukemia" refers to broadly progressive, malignant
diseases of the blood-forming organs and is generally characterized
by a distorted proliferation and development of leukocytes and
their precursors in the blood and bone marrow. Leukemia diseases
include, for example, acute nonlymphocytic leukemia, chronic
lymphocytic leukemia, acute granulocytic leukemia, chronic
granulocytic leukemia, acute promyelocytic leukemia, adult T-cell
leukemia, aleukemic leukemia, a leukocythemic leukemia, basophylic
leukemia, blast cell leukemia, bovine leukemia, chronic myelocytic
leukemia, leukemia cutis, embryonal leukemia, eosinophilic
leukemia, Gross' leukemia, hairy-cell leukemia, hemoblastic
leukemia, hemocytoblastic leukemia, histiocytic leukemia, stem cell
leukemia, acute monocytic leukemia, leukopenic leukemia, lymphatic
leukemia, lymphoblastic leukemia, lymphocytic leukemia,
lymphogenous leukemia, lymphoid leukemia, lymphosarcoma cell
leukemia, mast cell leukemia, megakaryocytic leukemia,
micromyeloblastic leukemia, monocytic leukemia, myeloblastic
leukemia, myelocytic leukemia, myeloid granulocytic leukemia,
myelomonocytic leukemia, Naegeli leukemia, plasma cell leukemia,
plasmacytic leukemia, promyelocytic leukemia, Rieder cell leukemia,
Schilling's leukemia, stem cell leukemia, subleukemic leukemia, and
undifferentiated cell leukemia.
[0024] The term "sarcoma" generally refers to a tumor which arises
from transformed cells of mesenchymal origin. Sarcomas are
malignant tumors of the connective tissue and are generally
composed of closely packed cells embedded in a fibrillar or
homogeneous substance. Sarcomas include, for example,
chondrosarcoma, fibrosarcoma, lymphosarcoma, melanosarcoma,
myxosarcoma, osteosarcoma, Abemethy's sarcoma, adipose sarcoma,
liposarcoma, alveolar soft part sarcoma, ameloblastic sarcoma,
botryoid sarcoma, chloroma sarcoma, chorio carcinoma, embryonal
sarcoma, Wilns' tumor sarcoma, endometrial sarcoma, stromal
sarcoma, Ewing's sarcoma, fascial sarcoma, fibroblastic sarcoma,
giant cell sarcoma, granulocytic sarcoma, Hodgkin's sarcoma,
idiopathic multiple pigmented hemorrhagic sarcoma, immunoblastic
sarcoma of B cells, lymphomas (e.g., Non-Hodgkin Lymphoma),
immunoblastic sarcoma of T-cells, Jensen's sarcoma, Kaposi's
sarcoma, Kupffer cell sarcoma, angiosarcoma, leukosarcoma,
malignant mesenchymoma sarcoma, parosteal sarcoma, reticulocytic
sarcoma, Rous sarcoma, serocystic sarcoma, synovial sarcoma, and
telangiectaltic sarcoma.
[0025] The term "melanoma" is taken to mean a tumor arising from
the melanocytic system of the skin and other organs. Melanomas
include, for example, acral-lentiginous melanoma, amelanotic
melanoma, benign juvenile melanoma, Cloudman's melanoma, S91
melanoma, Harding-Passey melanoma, juvenile melanoma, lentigo
maligna melanoma, malignant melanoma, nodular melanoma subungal
melanoma, and superficial spreading melanoma.
[0026] The term "effective amount" as used herein, refers to an
amount sufficient to achieve a desired or intended effect.
Method for Determining Sensitivity to Treatment
[0027] MYC gene (c-Myc) is a regulator gene that codes for a
transcription factor. The protein encoded by this gene is a
multifunctional, nuclear phosphoprotein that plays a role in cell
cycle progression, apoptosis and cellular transformation. MYC
overexpression induces aberrant proliferation by affecting
different biological processes, including gene transcription,
protein translation, and DNA replication. Sustained MYC activation
in mice creates a state of oncogene addiction while MYC withdrawal
in established tumors, including liver carcinomas, leads to tumor
involution. Additionally, owing to its role in mediating oncogenic
signals, MYC is required for the maintenance of some tumors in
which it is not amplified, including murine lung adenomas driven by
KRAS and leukemia driven by MLL-AF9. Despite the extensive
validation of MYC as a therapeutic target, small molecule MYC
antagonists are not available. In principle, the identification of
critical molecules and processes required for MYC action in cancer
provides an alternative strategy for targeting MYC-driven
tumors.
[0028] One aspect of the present application relates to a method of
determining sensitivity to cancer treatment in a patient suffering
from cancer, the method comprising the steps of determining the
presence in a biological sample from the patient of over-expression
of MYC in tumor tissue, wherein the presence of over-expression of
MYC indicates a sensitivity to treatment by a CDK9 inhibitor.
[0029] In some embodiments, the cancer is carcinoma, sarcoma,
melanoma or germ cell tumor. In other embodiments, the cancer is
carcinoma. In some embodiments, the cancer is selected from the
group consisting of liver cancer, lung adenocarcinoma, lymphoma,
leukemia, bladder cancer, gastric cancer, prostate cancer,
colorectal cancer, cutaneous melanoma, head and neck cancer,
low-grade glioma, cervical cancer, ovarian cancer, renal cancer and
breast cancer. In other embodiments, the cancer is bladder cancer.
In other embodiments, the cancer is hepatocellular carcinoma. In
yet other embodiments, the cancer is lymphoma, leukemia or
non-small cell lung carcinoma (NSCLC).
[0030] The biological sample can be a tissue sample, a biopsy
sample or a blood sample. The term "over-expression of MYC" refers
to a level of MYC expression that is significantly higher than the
level of MYC expression in a control sample or a reference value.
In some embodiments, "over-expression" refers to a level of
expression that is significantly higher than (1) the level of
expression in a control sample or (2) a reference value. In some
embodiments, "over-expression" refers to a level of expression that
is at least 20%, 50%, 100%, 150%, 200%, 300%, 400% or 500% higher
than the level of expression in a control sample or a reference
value. The level of MYC expression may be determined at
transcriptional level (e.g., by determining the level of MYC RNA),
at translational level (e.g., by determining the level of MYC
protein), or at functional level (e.g., by determining the level of
MYC activity).
[0031] Overexpression of MYC in tumor tissue samples can be
determined with methods well known in the art. All techniques that
are presently known, or which may be subsequently discovered, for
the evaluation of overexpression of a gene are contemplated for use
with the present application. Techniques for evaluating the
presence of overexpression of MYC in biological samples include
microarray analysis, differential display, PCR, RT-PCR, Q-RT-PCR,
Northern blots, Western blots, and Southern blots.
[0032] In some embodiments, antibodies are raised against the
expressed proteins of MYC in tumors and used to detect the presence
of mutations in such tumors by known techniques, such as
enzyme-linked immunosorbent assay (ELISA).
[0033] In certain embodiments primers are used to support
sequencing of nucleotides extracted from a tumor tissue sample.
Typically the primers will be capable of being extended in a
sequence specific manner. Extension of a primer in a sequence
specific manner includes any methods wherein the sequence and/or
composition of the nucleic acid molecule to which the primer is
hybridized or otherwise associated directs or influences the
composition or sequence of the product produced by the extension of
the primer. Extension of the primer in a sequence specific manner
therefore includes, but is not limited to, PCR, DNA sequencing, DNA
extension, DNA polymerization, RNA transcription, or reverse
transcription.
[0034] It is understood that in certain embodiments the primers can
also be extended using non-enzymatic techniques, where for example,
the nucleotides or oligonucleotides used to extend the primer are
modified such that they will chemically react to extend the primer
in a sequence specific manner. In other embodiments primers can be
extended using isothermal techniques. In some embodiments,
techniques and conditions are optimized for the amplification of
MYC RNA.
[0035] The biological samples can be a tissue sample, such as a
biopsy sample, body fluid sample, such as blood, lymph fluid,
spinal fluid and saliva, or cell sample from the patient. In some
embodiments, the biological sample is a biopsy sample collected
from a tumor within the patient.
[0036] Overexpression of MYC may be identified by standard
molecular biological techniques used to detect the presence of
specific biomarkers in a biological sample, such as a tumor tissue
sample. Techniques include the use of primers, probes or
antibodies, which are capable of interacting with the known RNA or
protein sequence of MYC.
[0037] In some embodiments, the overexpression of MYC determination
is performed on biopsies that are embedded in paraffin wax.
Formalin fixation and tissue embedding in paraffin wax is a
universal approach for tissue processing prior to light microscopic
evaluation. A major advantage afforded by formalin-fixed
paraffin-embedded (FFPE) specimens is the preservation of cellular
and architectural morphologic detail in tissue sections. The use of
FFPE specimens provides a means to improve current diagnostics by
accurately identifying the major histological types, even from
small biopsies. Since FFPE sample collection and storage is a
routine practice in pathology laboratories, this approach allows
analysis of overexpression of genes in archived tissues to
retrospectively determine sensitivity to CDK9 inhibitors.
[0038] As used herein, the term "CDK9 inhibitor" refers to agents
that inhibit expression of CDK9 gene or an activity of CDK9
protein. Examples of CDK9 inhibitors include, but are not limited
to, PHA 767491, PHA-793887, PHA-848125, BAY 1143572, BAY 1112054,
Cdk9 inhibitor II (CAS 140651-18-9 from Calbiochem), DRB, AZD-5438,
SNS-032, dinaciclib, LY2857785, flavopiridol, purvalanol B,
CDKI-71, CDKI-73, CAN508, FIT-039, CYC065,
3,4-dimethyl-5-[2-(4-piperazin-1-yl-phenylamino)-pyrimidin-4-yl]--
3H-thiazol-2-one, wogonin, apigenin, chrysin, luteolin,
4-methyl-5-[2-(3-nitroanilino)pyrimidin-4-yl]-1,3-thiazol-2-amine,
shRNAs against CDK9, anti-sense mRNA against CDK9 and anti-CDK9
antibodies.
[0039] In some embodiments, biological sample from the patient is a
biopsy sample of hepatocellular carcinoma. In some embodiments, the
presence of overexpression of the MYC gene in the biopsy sample
indicates a sensitivity to the treatment by a CDK9 inhibitor, such
as PHA 767491 or an anti-CDK9 shRNA.
[0040] In some embodiments, the method further comprises the step
of administering to the patient an effective amount of a CDK9
inhibitor, if overexpression of MYC is found in the biological
sample.
[0041] In some embodiments, the cancer is hepatocellular carcinoma
and the absence of overexpression of MYC indicates that the
hepatocellular carcinoma is likely to be unresponsive to CDK9
inhibitors. The patient is advised to undergo surgery to remove the
hepatocellular carcinoma without accompanying use of therapeutic
CDK9 inhibitors. In other embodiments, the cancer is hepatocellular
carcinoma and the presence of overexpression of MYC indicates that
the hepatocellular carcinoma is likely to be responsive to CDK9
inhibitors. The patient is advised to undergo surgery to remove the
hepatocellular carcinoma with administration of CDK9 inhibitors
prior to, or after, or both prior to and after, the surgery.
[0042] Another aspect of the present application relates to a
method of evaluating the efficacy of administering CDK9 inhibitors
in a patient suffering from cancer. The method comprises the steps
of determining the presence in a biological sample from the patient
of suppressed levels of phosphorylation of Ser2 on the C-terminal
repeat domain (CTD) of RNA Pol II, wherein the presence of a
suppressed level of phosphorylation of Ser2 on the CTD of RNA Pol
II is indicative that CDK9 is being inhibited in the patient. As
used herein, a "suppressed level of phosphorylation" refers to a
level of phosphorylation that is significantly lower than (1) the
level of phosphorylation on a control sample or (2) a reference
level. In some embodiments, "a suppressed level of phosphorylation"
refers to a level of phosphorylation that is about 90%, 80%, 70%,
60%, 50%, 40%, 30%, 20%, 10% or lower than the level of
phosphorylation in a control sample or a reference value. The level
of phosphorylation of Ser2 on the CTD of RNA Pol II may be
determined using methods well known in the art. Techniques for
determining the level of phosphorylation of Ser2 on the CTD of RNA
Pol II in biological samples include Western blots,
Immunohistochemistry (IHC), Immunocytochemistry (ICC), and
enzyme-linked immunosorbent assay (ELISA) and Mass spectrometry
(MS).
[0043] The presence in a biological sample from a patient of
suppressed levels of phosphorylation of Ser2 on the CTD of RNA Pol
II, may be detected by any of the standard molecular biological
techniques used to detect the presence of phosphorylation of an
amino acid position, including those listed herein.
[0044] If the presence of suppressed levels of phosphorylation of
Ser2 on the CTD of RNA Pol II is found within the tumor tissue
sample from the patient, greater efficacy may be predicted if a
regimen of CDK9 inhibitors is prescribed for the patient. If the
presence of a suppressed levels of phosphorylation of Ser2 on the
CTD of RNA Pol II is not found within the tumor tissue, then a CDK9
inhibitor is not efficacious.
Method for Treating Cancer
[0045] Another aspect of the application relates to a method of
treating a patient suffering from cancer. The method comprising the
steps of determining the presence in a biological sample from the
patient of overexpression of MYC associated sensitivity to
administration of a CDK9 inhibitor, and administering an effective
amount of a CDK9 inhibitor to the patient if overexpression of MYC
is detected in the sample.
[0046] In some embodiments, the cancer is carcinoma, sarcoma,
melanoma or germ cell tumor. In other embodiments, the cancer is
carcinoma. In some embodiments, the cancer is selected from the
group consisting of carcinomas, lymphomas and leukemia. In other
embodiments, the cancer is hepatocellular carcinoma. In yet other
embodiments, the cancer is lymphoma, leukemia or NSCLC.
[0047] In some embodiments, an effective amount of one or more CDK9
inhibitors is administered. Each CDK9 inhibitor may be administered
at a dose of 0.05-500 mg/m.sup.2 per cycle, 0.05-0.2 mg/m.sup.2 per
cycle, 0.05-0.5 mg/m.sup.2 per cycle, 0.05-2 mg/m.sup.2 per cycle,
0.05-5 mg/m.sup.2 per cycle, 0.05-20 mg/m.sup.2 per cycle, 0.05-50
mg/m.sup.2 per cycle, 0.05-100 mg/m.sup.2 per cycle, 0.05-200
mg/m.sup.2 per cycle, 0.2-0.5 mg/m.sup.2 per cycle, 0.2-2
mg/m.sup.2 per cycle, 0.2-5 mg/m.sup.2 per cycle, 0.2-20 mg/m.sup.2
per cycle, 0.2-50 mg/m.sup.2 per cycle, 0.2-100 mg/m.sup.2 per
cycle, 0.2-200 mg/m.sup.2 per cycle, 0.2-500 mg/m.sup.2 per cycle,
0.5-2 mg/m.sup.2 per cycle, 0.5-5 mg/m.sup.2 per cycle, 0.5-20
mg/m.sup.2 per cycle, 0.5-50 mg/m.sup.2 per cycle, 0.5-100
mg/m.sup.2 per cycle, 0.5-200 mg/m.sup.2 per cycle, 0.5-500
mg/m.sup.2 per cycle, 2-5 mg/m.sup.2 per cycle, 2-20 mg/m.sup.2 per
cycle, 2-50 mg/m.sup.2 per cycle, 2-100 mg/m.sup.2 per cycle, 2-200
mg/m.sup.2 per cycle, 2-500 mg/m.sup.2 per cycle, 5-20 mg/m.sup.2
per cycle, 5-50 mg/m.sup.2 per cycle, 5-100 mg/m.sup.2 per cycle,
5-200 mg/m.sup.2 per cycle, 5-500 mg/m.sup.2 per cycle, 20-50
mg/m.sup.2 per cycle, 20-70 mg/m.sup.2 per cycle, 20-100 mg/m.sup.2
per cycle, 20-200 mg/m.sup.2 per cycle, 20-500 mg/m.sup.2 per
cycle, 50-70 mg/m.sup.2 per cycle, 50-100 mg/m.sup.2 per cycle,
50-200 mg/m.sup.2 per cycle, 50-500 mg/m.sup.2 per cycle, 70-100
mg/m.sup.2 per cycle, 70-150 mg/m.sup.2 per cycle, 70-200
mg/m.sup.2 per cycle, 70-300 mg/m.sup.2 per cycle, 70-400
mg/m.sup.2 per cycle, 70-500 mg/m.sup.2 per cycle, 100-150
mg/m.sup.2 per cycle, 100-200 mg/m.sup.2 per cycle, 100-300
mg/m.sup.2 per cycle, 100-400 mg/m.sup.2 per cycle, 100-500
mg/m.sup.2 per cycle, 200-300 mg/m.sup.2 per cycle, 200-400
mg/m.sup.2 per cycle, 200-500 mg/m.sup.2 per cycle, 300-400
mg/m.sup.2 per cycle, 300-500 mg/m.sup.2 per cycle and 400-500
mg/m.sup.2 per cycle. In some embodiments, the CDK9 inhibitor is
administered at about 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100
mg/m.sup.2 per cycle. Each cycle may have a length of 1, 2, 3, 4,
5, 6, 7, 8 9 or 10 days, or 1, 2, 3, 4, 5, 6, 7, 8 or 9 weeks.
[0048] The CDK9 inhibitor may be administered parentally,
intravenously, intra muscularly, subcutaneously, or orally.
[0049] In some embodiments, the CDK9 inhibitor is administered at a
dose of 10-100 mg/m.sup.2 per cycle, 10-20 mg/m.sup.2 per cycle,
20-40 mg/m.sup.2 per cycle, 40-60 mg/m.sup.2 per cycle, 60-80
mg/m.sup.2 per cycle, or 80-100 mg/m.sup.2 per cycle The dose range
for CDK9 inhibitor administration as part of the methods disclosed
herein ranges between 20 mg/m.sup.2 to 100 mg/m.sup.2 CDK9
inhibitor. In some embodiments, CDK9 inhibitor is given
parenterally. In some embodiments, CDK9 inhibitor at the above
described dose is given by IV infusion over 3-24 hours. CDK9
inhibitors are commercially available from many sources. The dose
to be administered to a subject having a cancer can be determined
by a physician based on the subject's age, and physical condition,
the sensitivity of the cancer to an antineoplastic agent the nature
of the cancer and the stage and aggressiveness of the cancer. The
dosage ranges herein are not intended to limit the scope of the
invention in any way. In some instances dosage levels below the
lower limit of the aforesaid dose range may be more than adequate,
while in other cases still larger doses may be employed without
causing any harmful side effect.
[0050] In other embodiments, a CDK9 inhibitor, is administered in
conjunction with surgery that removes the cancer tissue containing
an overexpression of MYC. In some embodiments, the CDK9 inhibitor
is administered before surgery and after surgery. In other
embodiments, the CDK9 inhibitor is administered after surgery.
[0051] In some embodiments, a CDK9 inhibitor, is administered
before, after or in conjunction with radiation therapy.
[0052] In some embodiments, a combination of CDK9 inhibitors and
other chemotherapeutic agents, such as taxanes, Teniposide,
Gemcitabine, Dacarbazine, Flumequine and anthracyclines is
administered.
[0053] In some embodiments, a combination of CDK9 inhibitors and
other inhibitors, such as Sorafenib, Atorvastatin, tivantinib,
sunitinib and Crizotinib is administered.
Kits
[0054] Another aspect of the present application relates to a kit
for practicing the methods of the application. Kits of the
application may supply the means to detect overexpression of MYC in
a biological sample obtained from patient who is a candidate for
treatment with a CDK9 inhibitor. In some embodiments, the kit is a
package or a container comprising one or more reagents for
specifically detecting overexpression of MYC in a biological
sample. In some embodiments, the one or more reagents comprise two
or more nucleotide primers or probes that specifically hybridize to
one or more MYC RNA transcripts, or alternatively, antibodies for
detection of MYC protein.
[0055] In some embodiments, the kit comprises comprise one or more
reagents for determining the level of phosphorylation of Ser2 on
the CTD of RNA Pol II. The level of phosphorylation of Ser2 on the
CTD of RNA Pol II may be determined using methods well known in the
art. Techniques for determining the level of phosphorylation of
Ser2 on the CTD of RNA Pol II in biological samples include Western
blots, Immunohistochemistry (IHC), Immunocytochemistry (ICC), and
enzyme-linked immunosorbent assay (ELISA) and Mass spectrometry
(MS).
[0056] In other embodiments, the kit comprises a package insert
describing the kit and methods for its use.
[0057] In some embodiments, the kits comprises one or more of the
components selected from the group consisting of (1) containers for
processing biological samples to obtain nucleotide molecules, in
particular RNA, or proteins; (2) reagents for processing biological
samples to obtain nucleotide molecules or proteins; (3) RNA
purification and filtration components, such as microbeads, or
protein purification and filtration components, such as anion
exchange columns; (4) reagents for RNA filtration and purification,
or protein filtration and purification; (5) primers and/or other
synthetic oligonucleotides to be used for molecular biology
techniques for nucleotide sequence analysis, including RNA
sequencing; (6) microarrays designed for nucleotide or protein
sequence analysis, including hybrid capture arrays; (7) reagents
for determining the level of phosphorylation of Ser2 on the CTD of
RNA Pol II, and (8) means by which nucleotide sequences or antibody
binding may be visualized, including software programs.
[0058] The foregoing descriptions of specific embodiments of the
present application have been presented for purposes of
illustration and description. They are not intended to be
exhaustive or to limit the application and method of use to the
precise forms disclosed. Obviously many modifications and
variations are possible in light of the above teaching. It is
understood that various omissions or substitutions of equivalents
are contemplated as circumstance may suggest or render expedient,
but is intended to cover the application or implementation without
departing from the spirit or scope of the claims of the present
application.
EXAMPLES
Example 1
Material and Method
Pooled Negative Selection RNAi Screening
[0059] A custom shRNA library focused on 442 drug target genes was
designed using miR30-adapted BIOPREDsi predictions (six shRNAs per
gene) and constructed by PCR-cloning a pool of oligonucleotides
synthesized on 55k customized arrays (Agilent Technologies) as
previously described (Zuber J, McJunkin K, Fellmann C, Dow L E,
Taylor M J, Hannon G J, Lowe S W. 2011. Toolkit for evaluating
genes required MYC depends on transcription elongation for
proliferation and survival using tetracycline-regulated RNAi (Zuber
J et al., Nat Biotechnol (2011) 29: 79-83; Zuber J, et al., Nature
(2011) 478: 524-528.). The list of genes was obtained from DrugBank
(version 2.5; http://www.drugbank.ca) and was manually curated,
excluding ambiguous or redundant targets. After sequence
verification, 2245 shRNAs (five to six per gene) were combined with
several positive and neutral control shRNAs (n=20) at equal
concentrations in one pool.
[0060] The library was cloned into TRMPV-Neo and transduced into
Tet-on murine HCC MP1 cells using conditions that predominantly
lead to a single retroviral integration and represent each shRNA in
a calculated number of at least 1000 cells. Transduced cells were
selected for 5 d using 1 mg/mL G418 (Invitrogen); at each passage,
>20 million cells were maintained to preserve library
representation throughout the experiment. After drug selection, T0
samples were obtained (20 million cells per replicate) and sorted
for Venus+cells. After 12 d (six passages, T12), .about.20 million
shRNA-expressing (dsRed+Venus+) cells were sorted for each
replicate using a FACSAriaII (BD Biosciences). Genomic DNA from T0
and T12 samples was isolated by two rounds of phenol extraction
using PhaseLock tubes (5 Prime) followed by isopropanol
precipitation.
[0061] Statistical significance was calculated by two-tailed
Student's t-test. Correlation was calculated by Pearson test. Prism
5 software was used to calculate the IC50 values. Significance
values are P<0.05 (*), P<0.01 (**), and P<0.001 (***).
[0062] Total RNA was isolated using RNeasy Mini Kit and RNase-Free
DNase Set (Qiagen). Total mRNA was isolated using Oligotex mRNA
Mini Kit (Qiagen) following manufacturer's instructions. cDNA
synthesis and qRT-PCRs were performed as previously described (Xue
W et al., Nature (2007) 445: 656-660.). Quantitative PCR analysis
was performed on a ViiA.TM. 7 (Life Technologies). All signals were
quantified using the deltaCt method and were normalized to the
levels of GAPDH. Each reaction was done in triplicate using
gene-specific primers.
[0063] Deep-sequencing template libraries were generated by PCR
amplification of shRNA guide strands as previously described (Zuber
et al. Genes Dev (2011) 25:1628-1640). Libraries were analysed on
an Illumina Genome Analyser at a final concentration of 8 pM; 50
nucleotides of the guide strand were sequenced using a custom
primer. To provide a sufficient baseline for detecting shRNA
depletion in experimental samples, the experiment aimed to acquire
500 reads per shRNA in the T0 sample, which required more than
twenty million reads per sample to compensate for disparities in
shRNA representation inherent in the pooled plasmid preparation or
introduced by PCR biases. With these conditions, the experiment
acquired T0 baselines of >500 reads for 2246 (99.16% of all)
shRNAs. Sequence processing was performed using a customized Galaxy
platform (Taylor J, Schenck I, Blankenberg D, Nekrutenko A. 2007.
Using galaxy to perform large-scale interactive data analyses. Curr
Protoc Bioinformatics Chapter 10: Unit 10 15.).
Animal Studies
[0064] All mouse experiments were approved by the Memorial
Sloan-Kettering Cancer Center (MSKCC) Animal Care and Use Committee
(protocol no. 11-06-011). Mice were maintained under specific
pathogen-free conditions, and food and water were provided ad
libitum. For conditional RNAi experiments in vivo, Tet-on murine
HCC MP1 cells were transduced with luciferase-hygro and
TRMPV-Neo-miR-E shRNA constructs. One million murine or human HCC
cells were ortothopically transplantated into female nude recipient
mice (NCR nu/nu, purchased from Charles River laboratories and
Harlan Laboratories), as described previously (Saborowski et al.
2013 Proc Natl Acad Sci USA. 2013 Nov. 26; 110(48):19513-8. doi:
10.1073/pnas.1311707110.). For whole-body bioluminescent imaging,
mice were intraperitoneally injected with 50 mg/kg D-Luciferin
(Goldbio), and after 10 min, analysed using an IVIS Spectrum system
(Caliper LifeSciences). Quantification was performed using Living
Image software (Caliper LifeSciences) with standardized round
regions of interests covering the mouse trunk and extremities. For
shRNA induction, animals were treated with doxycycline in drinking
water (2 mg/ml with 2% sucrose; Sigma-Aldrich) and food (625 mg/kg,
Harlan Laboratories). For PHA-767491 treatment trials, PHA-767491
was solved in ultrapure distilled water, filtered by 0.2 .mu.M
filters, and diluted to a final concentration of 5 mg/ml. Mice were
orally given twice daily PHA-767491 (50 mg/kg) or a similar volume
of vehicle (water). The sick animals were sacrificed and liver
tumors were used for further analysis. Liver tumors were excised,
formalin-fixed and paraffin-embedded, frozen, or embedded in
OCT.
[0065] To produce Tet-on murine HCC cells, liver progenitor cells
from p53Loxp/Loxp mouse were transduced with CreER and
Myc-IRES-rtTA3 and then transplanted into recipient mice. After
tumor formation, the tumor was established as a cell line and
different clones were tested for their ability to induce shRNAs
expressed from TRMPV-neo in the presence of doxycycline, and for
functionality using neutral (Renilla) and lethal (Rpa3) control
shRNAs in competitive proliferation assays. In this assay,
shRNA-expressing and non-expressing cells were mixed and tested for
their relative proliferation potential. Taking into account the
similar behavior of the different clones, Myc;p53-/- clone #1 was
selected as the screening cell line (hereafter, referred to as
MP1).
[0066] The remaining HCC murine cell lines were derived from liver
progenitor cells from p53LoxP/LoxP mice: MP-CH stands for
Myc;p53-/- (similar to MP1) but was generated from independent
infections; Myc-AL was generated by overexpressing Myc cDNA in
p53LoxP/LoxP liver progenitor cells although p53 locus is intact;
KrasG12D;p53-/- cells were originated by overexpressing mutant Kras
and deleting p53.
Plasmids
[0067] For conditional RNAi experiments, shRNAs were expressed from
the TRMPV-Neo vector from either miR-30 or miR-E backbones, which
have been described previously (and are available from Addgene,
catalog no. 27990, or on request (e.g. Zuber J, et al. Nat
Biotechnol (2011) 29: 79-83; Fellmann C, et al., Hoffmann T. et
al., Cell Rep (2013) 5: 1704-1713.). To produce Tet-on murine HCC
MP1 cells, liver progenitor cells from p53Loxp/Loxp mice were
transduced with CreER and Myc-IRES-rtTA3.
[0068] For MYC rescue experiments, the wild-type human MYC cDNA was
subcloned into MSCV-PGK-Puro-IRES-GFP (MSCV-PIG) (Hemann M T, et
al., Nat Genet, (2003) 33: 396-400.)
[0069] For the in vivo experiments, cancer cells were infected with
Luciferase-hygro. Human cell lines were infected with MSCV-RIEP
(MSCV-rtTA3-IRES-EcoR-PGK-Puro) (Zuber J, et al. Genes Dev (2011)
25: 1628-1640.). Knockdown efficiency or overexpression was
evaluated by immunoblotting. shRNA sequences are available. The pT3
transposon and pT3-EF1a-Myc vectors were a kind gift of Dr. Xin
Chen, University of California at San Francisco. To generate the
constitutive expression vector pT3-EF1a (Tschaharganeh D F, et al.
Cell (2014). July 31; 158(3):579-92. doi:
10.1016/j.cell.2014.05.051.), the CpG-free EF1a promoter from
pCpGfree-vitroBmcs (InvivoGen) was inserted into pT3, and a
GFP-miR-E fragment was cloned following the EF1a promoter.
Immunoblotting
[0070] Liver tissues and cell pellets were lysed in Laemmli buffer
or protein lysis buffer (200 mM NaCl, 0.2% NP40, 50 mM Tris at pH
7.5, 1% Tween20, protease and phosphatases inhibitors) using a
tissue homogenizer. Equal amounts of protein were separated on 12%
SDS-polyacrylamide gels and transferred to PVDF membranes. The
abundance of .beta.-actin was monitored to ensure equal loading.
Images were analyzed using the AlphaView software (ProteinSimple).
Detection in immunoblots was performed using antibodies for CDK9
(Santa Cruz Biotechnology), MCM6 (Santa Cruz Biotechnology), PSMB2
(Santa Cruz Biotechnology), .beta.-Actin (AC-15, Sigma), p53 (Leica
Biosystems), MYC (Abeam), CCNT1 (Santa Cruz Biotechnology),
phopho-Ser2 RNA Pol II (Cell Signaling), and RNA Pol II (Santa Cruz
Biotechnology). For Ki67 staining (VP-K451, Vector Laboratories),
organ samples were fixed in fresh 4% paraformaldehyde overnight at
4.degree. C. and further subjected to routine histological
procedures for embedding in paraffin. Images were taken on a Zeiss
Axio Imager Z2 system.
Proliferation Assays
[0071] Competitive proliferation assays using shRNAs in TRMPV-Neo
vector (with miR-30 or miR-E backbone) were performed as described
previously (Zuber J, et al. Nature (2011) 478: 524-528).
Proliferation assays for PHA-767491 were performed in vitro by
counting the viable cell numbers over 72 h in the presence of
different PHA-767491 concentrations. Dead cells were excluded using
propidium iodide (PI) staining to score cells with sub-2N DNA
content. Measurements of cell concentration were performed on a
Guava Easycyte (Millipore), gating only viable cells (FSC/SSC/PI-).
Proliferation rates were calculated by dividing cell concentration
at 72 h and cell concentration at 0 h, divided by 72. Relative
proliferation rates were calculated by normalizing to the rate of
vehicle-treated cells. Population doublings were calculated by
calculating log 2 (cells at end point/cells at initial point)
divided by time in days.
shRNA Experiments in Human HCC Cell Lines
[0072] HepG2, Hep3B, SKHep1, SNU398, SNU475, and Alexander cells
were modified to express the ecotropic receptor and rtTA3 by
transducing MSCV-RIEP (MSCV-rtTA3-IRES-EcoR-PGK-Puro) followed by
drug selection (1 .mu.g/mL puromycin for 1 wk). The resulting cell
lines were transduced with ecotropically packaged TRMPV-Neo-shRNA
retroviruses with either miR-30 or miR-E backbone, selected with 1
mg/mL G418 for 1 wk, and treated with 1 .mu.g/mL dox to induce
shRNA expression. The relative change in Venus+dsRed+ (shRNA+)
cells was monitored on a Guava Easycyte (Millipore) by performing
proliferation competitive assays.
[0073] Deep-sequencing template libraries were generated by PCR
amplification of shRNA guide strands as previously described (Zuber
J, et al. 2011. Genes Dev 25: 1628-1640.). Libraries were analysed
on an Illumina Genome Analyser at a final concentration of 8 pM; 50
nucleotides of the guide strand were sequenced using a custom
primer. To provide a sufficient baseline for detecting shRNA
depletion in experimental samples, the experiment aimed to acquire
500 reads per shRNA in the T0 sample, which required more than
twenty million reads per sample to compensate for disparities in
shRNA representation inherent in the pooled plasmid preparation or
introduced by PCR biases. With these conditions, the experiment
acquired T0 baselines of >500 reads for 2246 (99.16% of all)
shRNAs. Sequence processing was performed using a customized Galaxy
platform (Taylor J, Schenck I, Blankenberg D, Nekrutenko A. 2007.
Using galaxy to perform large-scale interactive data analyses. Curr
Protoc Bioinformatics Chapter 10: Unit 10 15.).
[0074] Chromatin Immunoprecipitation (ChIP)
[0075] ChIP assays were performed as previously described (Bracken
A P, et al., Genes Dev (2006) 20: 1123-1136). Briefly,
cross-linking was performed with 1% formaldehyde, and cells were
lysed in SDS buffer. DNA was fragmented by sonication (Bioruptor).
ChIP for RNA Pol II was performed using a specific antibody (N-20,
Santa Cruz Biotechnology). DNA enrichment was measured by
quantitative PCR performed using SYBR Green (ABI) on a ViiA 7 (Life
Technologies). Each reaction was done in triplicate using
gene-specific primers. Each immunoprecipitate signal was referenced
to an input standard curve dilution series
(immunoprecipitate/input) to normalize for differences in starting
cell number and for primer amplification efficiency. Pausing index,
also known as traveling ratio, was calculated as the ratio between
the RNA Pol II bound to the transcription start site and the RNA
Pol II bound to the gene body.
[0076] Small Animal PET Imaging
[0077] For in vivo assays, human holo-Transferrin was labeled with
89Zr. The 89Zr was prepared as previously described (Holland J P,
Sheh Y, Lewis J S. 2009. Standardized methods for the production of
high specific-activity zirconium-89. Nucl Med Biol 36: 729-739.).
Female athymic nude mice were inoculated with 5.times.106 to
10.times.106 cells reconstituted in a 1:1 mixture of medium and
Matrigel in the shoulder. After tumors reached .about.500 mm3, mice
were treated with PHA-767491 for 3 d and, 2 d after, injected with
275-300 mCi of 89Zr-holoTransferrin via the tail vein. At various
time points following injection (24-48 h), mice were scanned using
a MicroPET Focus 120 Scanner (Concorde Microsystems). Approximately
5 min before recording PET images, mice were anesthetized by
inhalation of 1%-2% isoflurane (Baxter Healthcare) in an oxygen gas
mixture and placed on the scanner bed. Image reconstruction and
processing details have been reported elsewhere (Holland J P et
al., J Nucl Med (2010) 51: 1293-1300). For biodistribution studies,
mice (n=5; 10 tumors) were euthanized by CO2 at 48 h
post-injection, and organs were harvested immediately. The
radioactivity in each organ was counted alongside a known amount of
89Zr, the counts were correlated to activity, and decay was
corrected. The organs were then weighed, and the percentage of the
injected dose per gram (% ID/g) in each tissue was calculated.
[0078] Hydrodynamic Tail Vein Injection
[0079] A sterile 0.9% NaCl solution/plasmid mix was prepared
containing 5 .mu.g of DNA of pT3-EF1a-Myc and 20 .mu.g of DNA of
pT3-EF1a-GFP-miRe Transposon vector together with CMV-SB13
Transposase (1:5 ratio) for each injection. FVBN mice from JAX were
injected with the 0.9% NaCl solution/plasmid mix into the lateral
tail vein with a total volume corresponding to 10% of body weight
in 5-7 sec.
Example 2
RNAi Screen for Genes Encoding Known Drug Targets
[0080] Growth-inhibitory effects of several available CDK9
inhibitors have been compared with the anti-proliferative effects
of numerous CDK9 shRNAs and a lead compound identified (PHA-767491,
a dual CDC7/CDK9 inhibitor) that most closely recapitulated
shRNA-mediated CDK9 inhibition in both human and murine cell lines.
While this molecule shows both in vitro and in vivo efficacy, given
its extremely simple structure increased potency, selectivity, and
pharmacodynamics can be obtained by modifying its scaffold.
[0081] In order to get improved CDK9 inhibitors for the clinical
management of MYC-overexpressing tumors, PHA-767491 was docked into
the existing crystal structure of CDK9 and CDC7 and identified
potential regions of the molecule that can be derivatized to
improve potency, selectivity, and pharmacodynamics. In this
project, a number of these structures are synthesized, utilizing
the Organic Synthesis Core Facility at MSKCC or, potentially,
Takeda, and in vitro potency and selectivity is tested using
well-established kinase assays. The best molecules identified are
moved to cell-based validation assays, using Ser2 phosphorylation
of RNA Pol II as a biomarker. A panel of murine and human cancer
cell lines can be provided, which exhibit differential sensitivity
to CDK9 shRNAs, and it is possible to compare the IC50's generated
with the above molecules to further confirm compound selectivity.
Kinome-wide assays such as KiNativ can be employed to further
confirm the specificity of identified compounds in situ. Finally,
the best candidates are tested in established in vivo models, and
using the Antitumor Assessment core at MSKCC, it is possible to
define the pharmacodynamics parameters for these compounds.
[0082] The exemplary approaches are based on the finding that
PHA-767491 is more selective for CDK9 than other available
inhibitors. It is also possible to modify the scaffolds of other
previously identified CDK9 inhibitors.
[0083] By defining CDK9 inhibition as an "anti-MYC" approach here,
it is possible to identify a patient selection criteria (high MYC)
and a pharmacodynamics marker (Ser2 phosphorylation of RNA Pol II),
which can greatly facilitate preclinical and clinical development
of this strategy in both hematological and solid cancers.
[0084] To systematically probe candidate drug targets required for
HCC maintenance, exemplary embodiment of a screening platform and
shRNA library can be provided to facilitate the identification of
cancer dependencies in a defined genetic context. For this
screening system, the experiment established a murine HCC model
driven by Myc overexpression and p53 loss, which mimics two of the
most common genetic drivers in human HCC. These cells also
expressed a reverse tetracycline transactivator (rtTA) that enabled
efficient induction of tet-responsive transgenes introduced by
retroviral mediated gene transfer.
[0085] To focus on genes whose protein products can be targeted by
established agents, the screen used a custom shRNA library against
442 genes encoding known drug targets (.about.6 shRNAs/gene) (FIG.
1A). This target list consisted of genes involved in metabolism,
protein modifications, signal transduction, and macromolecular
transport (FIG. 1B), with a bias for receptors and kinases. The
shRNAs were cloned downstream of a tetracycline responsive promoter
in TRMPV-neo (FIG. 1A), an inducible expression vector that was
previously optimized for negative-selection RNAi screens.
[0086] The library was transduced as one pool in triplicate into
murine Myc;p53-/- HCC cells (hereafter, MP1 cells) at low
multiplicity of infection (MOI<1). Transduced cells were
cultured such that, in theory, each shRNA was represented in at
least 1000 cells throughout the experiment (FIG. 1C). After G418
selection, shRNAs were induced by addition of doxycycline (dox),
and changes in shRNA representation after 12 days of culture were
quantified using deep sequencing of shRNA guide strands amplified
from genomic DNA of sorted shRNA-expressing cells (FIG. 1C). The
correlation of normalized shRNA reads present in the replicates at
T0 was close to 1 but substantially decreased when comparing T0 and
T12 within the same replicate, suggesting changes in library
representation associated with shRNA depletion (FIG. 1D).
[0087] Using the scoring criterion of more than 5-fold average
depletion in three independent replicates, 43 shRNAs were strongly
depleted (FIG. 1E): these included all positive-control shRNAs
targeting essential genes (Rpa1, n=1; Rpa3, n=5; Pcna, n=1) as well
as three shRNAs targeting Myc--the driving oncogene in this model.
For a hit to undergo further analysis, it required that at least
two independent shRNAs targeting a particular gene were identified
in the primary screen. Genes fulfilling these criteria included the
proteasome component Psmb2 (proteasome subunit beta type 2), the
replication factor Mcm6 (minichromosome maintenance complex
component 6), and the transcription elongation factor CDK9
(cyclin-dependent kinase 9).
Example 3
Competitive Inhibition Assay
[0088] To identify targets whose inhibition showed selective
anti-proliferative effects in cancer cells, the positive hits above
in the MP1 cells used in the screen were validated, and then those
that showed a similar effect on non-transformed immortalized mouse
embryo fibroblasts (iMEFs) were filtered out. shRNAs targeting
Rpa3, an essential gene, and Myc, the oncogenic driver in the
screened MP1 cell line, were used as positive-controls; a Renilla
luciferase shRNA was used as negative-control. All selected shRNAs
produced a competitive disadvantage in MP1 cells (FIG. 2A),
confirming that the screen performance and the selection criteria
were sufficient to remove false positive events. Moreover, each
validated shRNA showed substantial knockdown of the intended
protein, further indicating that the observed phenotypes were due
to on-target effects (FIG. 2B).
[0089] shRNAs targeting Mcm6 and Psmb2 inhibited iMEFs and MP1
cells to a similar extent, suggesting that inhibition of their
target proteins was generally lethal, much like the control Rpa3
shRNA (FIGS. 2C and 2D). By contrast, CDK9 shRNAs showed a reduced
ability to inhibit proliferation in iMEFs as compared to MP1 cells
(FIGS. 2C and 2D), an effect that was similar to the Myc shRNA and
could not be accounted for by differences in proliferation rates of
iMEFs and MP1 cells or in shRNA knockdown (FIGS. 2B and 2D). Owing
to this apparent specificity, CDK9 became a candidate for more
detailed analysis.
[0090] To confirm that the impact of CDK9 inhibition on cancer cell
proliferation was not limited to one experimental HCC line,
additional murine and human cell lines engineered to express rtTA3
to allow dox-dependent shRNA induction were studied. Control
(Renilla and Myc) and CDK9 shRNAs were subcloned into miR-E, an
optimized miR-30-based backbone that increases knockdown
efficiency, particularly for those shRNAs with intermediate
potency. All three experimental murine HCC cell lines that
overexpressed Myc were sensitive to CDK9 inhibition, while murine
HCC cells expressing mutant KrasG12D, Hepa1-6 hepatoma cells,
NIH-3T3 fibroblasts, and iMEFs showed modest to no sensitivity
(FIG. 2E). Similarly, human HCC cell lines showed a range of
responses to human CDK9 shRNAs with some being highly sensitive and
others more resistant (FIG. 2F). Again, these differential
responses were independent of the proliferation rates of various
cell lines and the extent of CDK9 knockdown. Together, these
results indicate that that pharmacological inhibition of CDK9 may
have a therapeutic effect against certain cancers, such as HCC,
leukemia, lymphoma and NSCLC.
[0091] Available CDK9 inhibitors whose biology is most closely
related to CDK9 inhibition may show a spectrum of activity similar
to CDK9 shRNAs. The IC50 of several CDK9 inhibitors was compared
with the anti-proliferative effects of CDK9 shRNAs in competitive
proliferation assays (FIGS. 2E and 2F). After testing four
different CDK9 inhibitors, results identified PHA-767491, a dual
CDK9 and CDC7 (cell division cycle 7) kinase inhibitor, most
closely recapitulated shRNA-mediated CDK9 inhibition in both human
and murine cell lines (FIGS. 3A-3C). Notably, CDC7 in complexes
with its allosteric regulator, DBF4, is required for initiation of
DNA replication. However, exposure of cells to aphidicolin, an
inhibitor of DNA polymerase, did not mimic the effects of CDK9
shRNAs (FIG. 3A). In contrast, shRNAs directed to Cyclin T1
(CCNT1), an obligate allosteric regulator of the CDK9 kinase,
recapitulated the results obtained with CDK9 shRNAs (FIG. 3D),
thereby highlighting the specificity of these results.
[0092] The effect of PHA-767491 in additional human HCC cell lines
(FIGS. 3B and 3C) was evaluated. and broad anti-proliferative
activity in the most sensitive cell lines was observed (IC50<2
.mu.M) (FIG. 3E). PHA-767491 treatment triggered cell-cycle arrest,
similar to the effects of CDK9 shRNAs (FIG. 3E); however, the
anti-proliferative effects mediated by PHA-767491 were more
pronounced. Of note, two non-transformed cell lines were
consistently less sensitive to PHA-767491 treatment (FIGS. 3B and
3C), further supporting increased sensitivity of certain cancer
cells to CDK9 inhibition. While some of these phenotypes may be due
to CDC7 inhibition, the significant correlation between the IC50 of
PHA-767491 and the anti-proliferative effects of CDK9 shRNAs
implies that a major component of PHA-767491 activity is through
CDK9 inhibition. These data illustrate how using RNAi and small
molecule inhibitors as orthogonal approaches can assist target
validation and indicate that CDK9 can be required for HCC
proliferation.
Example 4
Predicting Response to CDK9 Inhibition
[0093] Since the screening system was driven by p53 loss and Myc
overexpression, alterations in either gene could dictate
sensitivity to CDK9 inhibition. Data on the relative sensitivity of
HCC cell lines to CDK9 inhibition (measured as the
growth-inhibitory effects of CDK9 shRNAs in competitive
proliferation assays or the IC50 of PHA-767491) was
cross-referenced to mutational and gene expression profiles of the
same cell lines available from the Cancer Cell Line Encyclopedia
(CCLE). The cross-referencing found no correlation between the
anti-proliferative response to CDK9 inhibition and p53 expression
or mutational status, consistent with previous findings indicating
that PHA-767491 inhibits cancer cell proliferation through
p53-independent mechanisms. However, there was a highly significant
correlation between the response to CDK9 inhibition and MYC mRNA
expression (FIGS. 4A and 4B), an effect that was confirmed by
immunoblotting for MYC protein (FIG. 4C). This significant
correlation was not limited to HCC cell lines but was also observed
in a panel of lung and hematopoietic cancer cell lines (FIG. 4A).
In all instances, no correlation was observed between sensitivity
to CDK9 inhibition and the relative proliferative rates of
individual cell lines nor was sensitivity related to MYC
amplification, indicating that MYC expression, rather than MYC
amplification status, is associated with the response to CDK9
inhibitors.
[0094] The transcriptional profiles of the 10 human HCC cell lines
with defined sensitivities to PHA-767491 were also subjected to
Gene Set Enrichment Analysis (GSEA) and Gene ontology (GO) analysis
to point towards genes and processes that might underlie their
differential sensitivity. This analysis revealed a significant
correlation between low IC50 (sensitivity to CDK9 inhibition) and
four canonical transcriptional signatures of MYC-dependent genes
(FIG. 4D), and a gene signature that defines a subclass of HCC
patients characterized by MYC and AKT activation (FIG. 4E). By
contrast, there was an inverse correlation between a gene
expression signature related to a different subclass of HCC
patients with WNT pathway activation and sensitivity to the drug.
MYC is a global regulator of gene expression that affects overall
transcription, ribosomal biogenesis, protein translation, and
cellular metabolism, and interestingly transcripts overrepresented
in sensitive compared to resistant cells were linked to "gene
expression", "RNA metabolic process" and "RNA processing" (FIG.
4F). Taken together, these results indicate that CDK9 might be
crucial for the maintenance of MYC-overexpressing tumors, and
identify a potential patient population that might be sensitive to
CDK9 inhibition.
[0095] After transcription initiation, RNA pol II is trapped near
the promoter of many genes, a process known as proximal promoter
pausing. For productive transcription, P-TEFb is recruited, and
CDK9 phosphorylates Ser2 in the C-terminal domain (CTD) of RNA pol
II, inducing pause-release and subsequent transcription elongation.
MYC has previously been shown to participate in transcription
elongation by regulating this pause release mechanism. Thus, in
MYC-overexpressing tumor cells, MYC accumulates in the promoter
region of many transcriptionally active genes, recruiting the
P-TEFb complex and amplifying transcription of MYC-target
genes.
[0096] To explore the role of CDK9 in MYC-mediated transcriptional
amplification, the effects of CDK9 inhibition in two human HCC cell
lines, HepG2 and Alexander, which express different levels of MYC,
were investigated (FIG. 4C). As expected, pharmacological or
RNAi-mediated suppression of CDK9 led to a decrease in Ser2
phosphorylation in both cell lines. In order to investigate whether
these changes correlated with changes in transcription elongation,
the investigation calculated the pausing index or travelling ratio
in which the ratio of RNA Pol II binding density in the proximal
promoter region is compared with that in the gene body. In HepG2
cells expressing high levels of MYC, inhibition of CDK9 (using
small molecules or shRNAs) or MYC caused a significant repression
of transcription elongation of NPM1 and MCM4, two select MYC
targets, and an increase in their pausing index (FIGS. 5A-5C).
However, no changes were observed for BRG1, whose transcription is
not impacted by MYC. In contrast, Alexander cells expressing much
lower MYC levels, the pausing index at the NPM1 and MCM4 genes was
already high in untreated cells and did not change substantially
following CDK9 or MYC inhibition (FIG. 5C). Accordingly, CDK9 or
MYC inhibition reduced mRNA levels of MYC target genes in HepG2
cells but not Alexander cells (FIG. 5D). Together, these results
indicate that CDK9 regulates the transcription elongation of MYC
targets NPM1 and MCM4 in the context of high MYC expression, and
that CDK9 inhibitors can reverse these effects.
Example 5
Competitive Proliferation Assays
[0097] MYC has been implicated in DNA replication, transcriptional
activation, transcription elongation and other processes, though
the relative contribution of each process to tumor initiation and
maintenance is not well understood. Despite the diversity of
factors involved in these processes, CDK9 and MYC shRNAs displayed
similar depletion patterns across multiple lines (FIGS. 2E and 2F)
and, in fact, there was a significant correlation between the
anti-proliferative effects of CDK9 and MYC shRNAs in competitive
proliferation assays (FIG. 6A). A similar correlation existed
between the anti-proliferative effects of Cyclin T1 and Myc shRNAs
(FIG. 6B).
[0098] To directly determine whether modulation of MYC activity
could influence cellular dependence on CDK9 activity, the
experiment tested the ability of enforced MYC expression to
influence sensitivity to CDK9 inhibition. Ectopic MYC expression in
the low MYC Alexander cells produced MYC levels.about.50% of those
measured in sensitive HepG2 cells and an increase in MYC-dependent
transcription elongation as measured by a reduced pausing index at
the NPM1 and MCM4 but not BRG1 genes (FIGS. 6C and 6D). This effect
on transcription elongation was accompanied by significant
increases in NPM1 and MCM4 mRNAs (FIG. 6E), while levels of BRG1
mRNA did not change (FIG. 6E). Concordantly, MYC-overexpressing
Alexander cells became more sensitive to CDK9 inhibition by
PHA-767491 or CDK9 shRNAs (FIG. 6F). While enforced MYC expression
in these cells did not produce the same sensitivity of high
MYC-expressing HepG2 cells, enforced MYC expression in SNU-475
cells achieved MYC levels equivalent to those observed in HepG2
cells (FIG. 6C) and produced a similar sensitivity to PHA-767491
(FIGS. 6F and 6G). The phenotypic similarities between MYC
inhibition and CDK9/CCNT inhibition indicate a key role for
transcription elongation in mediating MYC action in tumor
maintenance.
Example 6
RNAi-Mediated Suppression of CDK9 Approximates the Effect of Myc
Inhibition in Eliciting Anti-Tumor Effects in HCC In Vivo
[0099] To suppress CDK9 in established tumors in mice, MP1 murine
HCC cells were transduced with Luciferase and dox-inducible
TRMPV-Neo-miR-E constructs containing CDK9 shRNAs or control shRNAs
(Renilla and Myc), and were transplanted into the livers of
recipient mice by subcapsular injection. Upon detection of a
luminescent signal, the animals were randomized and treated with
dox to induce shRNA expression. Tumors bearing CDK9 shRNAs
exhibited a prominent decrease in the levels of Ser2
phosphorylation of RNA pol II, implying that transcription
elongation was efficiently repressed (FIG. 7A). By day 8,
bioluminescent imaging revealed that mice from the untreated group
(no dox) displayed large hepatic tumors; however, knockdown of CDK9
or Myc led to a comparable and significant delay in tumor growth
(FIGS. 7B and 7C). Ki67 staining of histological sections revealed
that tumors expressing shRNAs for CDK9 or Myc showed less
proliferation compared to tumors expressing the control Renilla
shRNA (FIG. 7D). Therefore, RNAi-mediated suppression of CDK9
approximates the effect of Myc inhibition in eliciting anti-tumor
effects in HCC in vivo.
[0100] Growth-inhibitory effects of pharmacological CDK9 inhibition
in a series of human HCC xenografts expressing luciferase were also
investigated. Treatment with PHA-767491 (50 mg/kg; twice a day; 5
days per week) or vehicle was initiated upon detection of
bioluminescence. Consistent with previous findings, PHA-767491
treatment was well tolerated in mice and triggered a decrease in
Pol II Ser2 phosphorylation in the emerging tumors (FIG. 7E). In
high MYC expressing HepG2 cells, PHA-767491 also decreased
tumor-cell proliferation, which was associated with substantial
inhibition of tumor growth and some tumor regressions (FIGS.
7F-7H). By marked contrast, the same treatment in low MYC
expressing Alexander cells produced little if any effect, despite
detectable decrease in Pol II Ser2 phosphorylation (FIGS. 7E-7H).
Thus, CDK9 is required for the maintenance of MYC-overexpressing
HCC, implicating transcriptional elongation as important for MYC
dependency in vivo.
Example 7
Liver Regeneration to Reveal the Therapeutic Index Associated with
CDK9 Inhibition In Vivo
[0101] miRE shRNA transposon vectors were injected into mice
together with CMV-SB13 transposase by hydrodynamic tail vein
injection and partial hepatectomy was performed after one week
(FIG. 8). Liver/body ratio and GFP percentage of the mice were
examined after two weeks. CDK9 inhibition does not show significant
impact on liver/body ratio, compared to Ren.713E (neutral control).
CDK9 inhibition does not show significant impact on the percentage
of GFP.sup.+ cells before and after partial hepatectomy.
Example 8
Inducible and Reversible Transgenic RNAi Mice Models
[0102] TRE-Driven miRE shRNAs are targeted to the ColA1 locus to
drive doxycycline (dox)-dependent genes knockdown in ES Cells,
embryonic and adult tissues of the mouse (FIG. 9). No significant
difference of the appearance between the mice.
* * * * *
References