Antireplication Agents: CDK Inhibitors and Telomerase Inhibitors

Richard S. Finn, MD

Assistant Professor of Medicine

Geffen School of Medicine at UCLA

Faculty Disclosure

Richard Finn, MD, has disclosed that he has received fees for non-CME services from Genentech.

Cyclin D Kinases and Cancer

CDKs are a subgroup of seine/ threonine kinases In general very small proteins (34-40 kDa) Bind to activating proteins: cyclins Without cyclins, CDKs have little kinase activity

Play a key role in regulating cell cycle progression through all phases of the cell cycle Various cyclin/ CDK complexes act at different parts of the cell cycle Temporal and quantitative regulation

Negative regulation by cyclin dependent kinase inhibitors (CKI) INK 4 family (p15, p16, 18, p19 Cip/ Kip family (p21, p27, p57)

Alterations in CDKs are uncommon, compared with cyclin dysregulation Altered regulation/ expression in many malignaices

Cyclin D1 amplification has been described in various malignancies, including breast cancer, with variable prognostic significance t(11;14) mantle cell lymphoma

Rb loss, a well known oncogenic event

1. Finn RS, et al. Breast Cancer Res. 2009;11:R77. 2. Lundberg AS, et al Eur J Cancer. 1999;35:1886-1894.3. Buckley MF, et al. Oncogene. 1993;8:2127-2133. 4. Dickson C, et al. Cancer Lett. 1995;90:43-50.

Cyclin D Kinases and Cancer

Vermullen Cell Proliferation

Modified from Figure 8.19 . The Biology of Cancer. © Garland Science 2007.

p16(INK4a)

Rb as Master-Regulator of the R Point

CDK/ Cyclin Inhibitors Targeting CDK

>50 inhibitors described Generally in several classes

– Purine analogoues (ie roscovitine) Selicicilib (CYC202) CDK2/E CDk 2/A CDK7 CDK 9

– Pyrimidine analgoues Dinaciclib (SCH727965) CDK 2, CDk5, CDK 1, CDK 9

– Flavonoids (flavopiridol)– Indolinones– Staurosporine

Targeting Cyclin cyclin expression modulators (ON013105)

CDK/ Cyclin Inhibitors Selicicilib (CYC202)

– Phase II Nasopharyngeal APPRAISE Study

Randomized Phase II, NSCLCA 3rd line or greater vs BSC

Dinaciclib (SCH727965) Phase II

– Melanoma– AML

ON013105 Phase I- mantle cell lymphoma

PD 0332991: Background

The compound

Potent, selective, reversible inhibitor of CDK4,6

Small molecule

Oral agent

The opportunity

Potential first in class

Potential impact on hematopoietic and solid tumors

Potential use in pediatric indications

Single-agent and combination approaches under investigation

NN O

N

NH

O

N

N

NH2

+

SO

OO

OH

PD 332991

Finn RS, et al. Breast Cancer Res. 2009;11:R77.

Inactivates Rb andallows progression

Target of PD 0332991

p16(INK4a)

Rb as Master-Regulator of the R Point

Modified from Figure 8.19 . The Biology of Cancer. © Garland Science 2007.

Sorlie et al PNAS 2001

Human Breast Cancer Cell Line Panel Can Recapitulate the Molecular Heterogeneity of Clinical Disease

51 HumanBreast Cell Lines

25 Luminal

26 Non-luminal

13 Basal/Progenitor

9 Mesenchyma

l

4 Non-malignant

10 ER positive

Normal HER-2

9 ER positive

HER-2 amplified

6 ER negative

HER-2 amplified

1 HER-2 Amplified

1 HER-2 Amplified

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Subtype Luminal Non-luminal/post EMT

HER2 Amplified Non-luminal Immortalized

PD-0332991: CDK 4/6 Inhibitor: Breast PanelIC

50 n

M

Finn RS Breast Can Res 2009

HCC 1419

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G0/G1 S G2

EFM192A

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MCF7

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G0/G1 S G2

HCC 1937

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MDA MB 468

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HCC 1187

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PD 0332991: Cell Cycle Analysis

Sensitive lines

Resistant linesFinn RS, et al. Breast Cancer Res. 2009;11:R77.

MB453

T47D

EFM19

HCC1187

HCC1954

CAL 51

A. Total pRb

Sensitive

Resistant

B. Phospho-Rb (serine 780)

MCF7

0 30’ 60’ 12 hr 24 hr 48 hr 12 hr30’ 48 hr60’ 24 hr0Time

Finn RS, et al. Breast Cancer Res. 2009;11:R77.

PD 0332991: Effects on Phosphorylation on Retinoblasoma Gene Product

Hypothesis: Patient Selection in Breast Cancer Population

ElevatedCyclin D1RB

Decreasedp16

Gauthier ML, et al. Cancer Cell. 2007;12:479-491.

MCF7

0

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10000 5000 2500 1250 625 312

100 50 25 12.5 6.25 3.125

Concentration (nM)

% In

hib

itio

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Tam

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% In

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EFM19

T47D

Tam

PD

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% I

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CI

Tam

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Concentration (nM)

CI

Tam

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1000 5000 2500 1250 625 312.5

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Concentration (nM)

CI

Combo

PD-2991

Tamoxifen

TRIO 18/A5481003: Phase I/II Study of Letrozole in Combinations With PD-0332991 in Postmenopausal ER+ Advanced Breast Cancer

Phase I complete

Randomized phase II accruing

ClincailTrials.gov. NCT00721409.

TRIO 18: Phase I Patient Summary

Slamon DJ, et al. ASCO 2010. Abstract 3060.

TRIO 18: Most Common AEs (N = 12)

PT, n Grade 1 Grade 2 Grade 3 Grade 4 Total

Neutropenia 0 1 7 2 10

Fatigue 6 2 0 0 8

Leukopenia 0 3 2 1 6

Nausea 5 0 0 0 5

Diarrhea 4 0 0 0 4

Anemia 2 1 0 0 3

Cough 2 1 0 0 3

Decreased appetite 3 0 0 0 3

Dyspnea 3 0 0 0 3

Hot flush 2 1 0 0 3

Nasal congestion 2 1 0 0 3

Arthralgia 1 1 0 0 2

Back pain 2 0 0 0 2

Creatinine increased 0 1 1 0 2

Slamon DJ, et al. ASCO 2010. Abstract 3060.

TRIO 18: Most Common Treatment-Related AEs (N = 12)

PT, n Grade 1 Grade 2 Grade 3 Grade 4 Total

Neutropenia 0 1 7 2 10

Fatigue 4 2 0 0 6

Leukopenia 0 3 2 1 6

Nausea 5 0 0 0 5

Anemia 2 1 0 0 3

Decreased appetite 3 0 0 0 3

Diarrhea 3 0 0 0 3

Hot flush 2 1 0 0 3

Dyspnea 2 0 0 0 2

Headache 1 1 0 0 2

Thrombocytopenia 1 1 0 0 2

Slamon DJ, et al. ASCO 2010. Abstract 3060.

TRIO 18: Phase I Summary

Phase I (N = 12)

• MTD: PD 0332991 125 mg QD (schedule 3/1) in combination with letrozole 2.5 mg QD

• 3 DLTs: – 2 patients with grade 4 neutropenia– 1 patient with 5 doses held due to elevated creatinine deemed treatment related

• No treatment-related SAEs

• No discontinuations due to AEs

– Common treatment-related AEs: neutropenia, leukopenia, fatigue

• No febrile neutropenia

• No drug-drug interaction

• Efficacy: 3 PRs and 9 SDs (PR: 33%; CBR: 67%)

• Median duration of treatment: 12 mos (range: 2-21+)

• Currently 6 patients activeSlamon DJ, et al. ASCO 2010. Abstract 3060.

Hypothesis: Biomarkers Predictive of PD 0332991 SensitivityDesired biomarker profile:

ER+, HER2-– Wild-type Rb1– Plus

• Amplified cyclin D1/CCND1

OR • Inactivated CDKN2A/p16INK4a

Finn RS, et al. Breast Cancer Res. 2009;11:R77.

Phase II Study Design (Part I, Completed)

ER+, HER2- breast cancer

Stratification Factors: Disease site

− Visceral vs bone only vs other

Disease-free interval− > 12 vs ≤ 12 mos

ER+, HER2- breast cancer

Stratification Factors: Disease site

− Visceral vs bone only vs other

Disease-free interval− > 12 vs ≤ 12 mos

RRAANNDDOOMMIIZZAATTIIOONN

RRAANNDDOOMMIIZZAATTIIOONN

Arm APD 0332991 125 mg/day

(Schedule 3/1)

+ Letrozole 2.5 mg/day

Arm APD 0332991 125 mg/day

(Schedule 3/1)

+ Letrozole 2.5 mg/day

Arm BLetrozole 2.5 mg/day

Arm BLetrozole 2.5 mg/day

N = 60

1:1

Primary endpoint: PFS

ClincailTrials.gov. NCT00721409.

Phase II Study Design (Part II, Ongoing)

ER+, HER2- breast cancer

Biomarker Selection

CCND1 amp

And/or loss of p16

ER+, HER2- breast cancer

Biomarker Selection

CCND1 amp

And/or loss of p16

RRAANNDDOOMMIIZZAATTIIOONN

RRAANNDDOOMMIIZZAATTIIOONN

Arm APD 0332991 125 mg/day

(Schedule 3/1)

+ Letrozole 2.5 mg/day

Arm APD 0332991 125 mg/day

(Schedule 3/1)

+ Letrozole 2.5 mg/day

Arm BLetrozole 2.5 mg/day

Arm BLetrozole 2.5 mg/day

N = 150

1:1

Primary endpoint: PFS

ClincailTrials.gov. NCT00721409.

Similar Observations in Other Histologies

Ovarian cancer[1]

Glioblastoma[2,3]

Multiple myeloma[4]

1. Konecny GE, et al. Clin Cancer Res. 2011;17:1591-1602. 2. Michaud K. Cancer Res. 2010;70:3228-3238. 3. Wiedemeyer WR, et al. Proc Natl Acad Sci U S A. 2010;107:11501-11506. 4. Menu E, et al. Cancer Res. 2008;68:5519-5523.

Telomerase and Cancer

Telomerase: reverse transcriptase that adds DNA repeats (TTAGGG) to the 3’ end of DNA strands (telomere region)– Consists of 2 molecules each of telomerase reverse transcriptase

(TERT), telomerase RNA (TERC), and dyskerin (DKC1)

Protects DNA from genomic damage/loss during replication

In cancer, cells that lose telomeres become unstable, accumulate genetic damage, and eventually undergo apoptosis

Activation of telomerase can prevent the apoptosis event and cause cells to become immortalized– Telomerase is activated in 90% of cancer (but not somatic cells)

Hypotheses: block telomerase, induce telomere shortening, genetic instability and cell death

Shay JW, et al. Human Mol Gen. 2001;10:677-685.

Telomerase MOA

Harley Nat rev Cancer 2008

Telomerase and Cancer

Various potential methods of silencing telomerase– Oligonucleotides

• Target the template region (activation site) of telomerase• Imetelstat (GRN163L): 13 mer oligonucleotide, not antisense but a direct

telomerase inhibitor[1]

– Vaccines• Dendritic cell–based (GRNVAC1)

• Use hTERT pulsed autologous dendritic cells• Phase I: generally well tolerated, achieved levels felt to be sufficient for

hTERT inactivation[2]

• Phase II study in AML as consolidation

• Nondendritic based • Phase I in solid tumors (V934/V935)[4]

• GV1001 peptide with temozolomide for melanoma[5]

1. Herbert BS, et al. Oncogene. 2005;24:5262-5268. 2. Su Z, et al. J Immunol. 2005;174:3798-3807. 3. ClinicalTrials.gov. NCT00510133. 4. ClinicalTrials.gov. NCT00753415. 5. ClinicalTrials.gov. NCT01247623.

Conclusions

Newer targets in molecular oncology include the CDK pathway and telomerase

Ongoing clinical studies (TRIO18) with PD 0332991, an oral, small molecule kinase inhibitor, in breast cancer aim at validating laboratory science that identified ER+ breast cancer as being susceptible to CDK 4/6 inhibition To date, predictable and manageable toxicity has been seen with this

class of agent

Studies with other CDK targeted agents and Cyclin targeted agents are ongoing MCL should be “proof of concept”

Telomerase inhibitors are moving to the clinic and hold promise but predictors of response will be necessary for successful clinical development Including vaccine strategies and short-oligos