DCTD Division of Cancer Treatment and Diagnosis

Pharmacodynamic Response in Phase I Combination Study of Veliparib (ABT-888) and Topotecan in Adults with Refractory

Solid Tumors and Lymphomas

J. Ji, S. Kummar, A. Chen, Y. Zhang, R. Putvatana, R. J. Kinders, L. Rubinstein, R. E. Parchment, J. E. Tomaszewski, and J. H. Doroshow

ASCO 46th Annual MeetingDevelopmental Therapeutics–Clinical Pharmacology and Immunotherapy

June 8, 2010

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Introduction

• Poly (ADP-ribose) polymerase (PARP) plays a key role in recognizing DNA damage and facilitating its repair; inhibition of PARP delays this repair.

– Veliparib (ABT-888), an orally available, small molecule PARP inhibitor, has been shown to increase the efficacy of several cytotoxic agents in preclinical xenograft tumor models.

– In a proof-of-principle Phase 0 clinical trial conducted at the National Cancer Institute, our validated PAR Immunoassay demonstrated decreased PAR levels in patient tumor and PBMC samples following Veliparib treatment.

• Kinders et al. 2008. Clin Cancer Res• Kummar et al. 2009. J Clin Oncol

• Topoisomerase 1 (TOP1) also plays a key role in DNA damage repair. Topotecan, a TOP1 inhibitor, is an FDA-approved chemotherapeutic agent.

Here we investigate the possible effects of Veliparib + topotecan on the DNA damage markers PAR and phosphorylated histone H2AX (H2AX).

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Measuring Pharmacodynamic Response Following Veliparib and Topotecan Treatment

H2AXP

H2AXP

BRCA1/2BRCA1/2

Dou

ble

Stra

nd B

reak

Rad51Rad51

Cell Death

Single Strand Break

Homologous/Non-homologous Recombination

PARPPARP

Cell SurvivalATR

ATM

Cell Cycle Checkpoints

TOP1TOP1

PAR Immunoassay

PAR Immunoassay

H2AX Immunofluorescence

Assay

H2AX Immunofluorescence

Assay

Topotecan Veliparib

Chk1/2

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Veliparib + Topotecan Phase I Clinical Trial Objectives

• Establish the safety, tolerability, and maximum tolerated dose (MTD) of the combination of Veliparib with topotecan in patients with refractory solid tumors and lymphomas.

• Evaluate the pharmacokinetics of each agent in combination.

• Determine the effects of the study treatment on the level of PARP inhibition and DNA damage in PBMCs and tumor samples.

Dose

Level

Dose and Days (D) of AdministrationNo. of

PatientsTopotecan IV (mg/m2/day) Veliparib PO (10 mg BID)

1 1.2 (D-8, D2-5) D1-7 6

-1 0.9 (D-8, D2-5) D1-7 3

-2 0.75 (D1-5) D2-5 3

-3 0.6 (D1-5) D2-5 7

-1A 0.75 (D1-5) D1 only 5

MTD

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Specimen Collection Specimen Preparation Pharmacodynamic Testing

Tumor Biopsy

0.0

5.0

10.0

15.0

20.0

25.0

30.0

Untreated 0.03 0.3 1 3

Topotecan Concentration (uM)

PAR Standard Curve 022507-1

1000000

10000000

100000000

10 100 1000 10000

PAR Std (pg/ml)

RL

U

PAR std(pg/ml)

SOP340503 Blood Collection and PBMC Processing

SOP340507 Tumor Frozen Needle Biopsy Collection and Handling

SOP340520 Tumor Protein Extraction

SOP340506 PBMC Protein ExtractionBlood

SOP340505 Poly (ADP-ribose) (PAR) Immunoassay

*http://dctd.cancer.gov/ResearchResources/ResearchResources-biomarkers.htm

Monitoring Pharmacodynamic ResponsePAR Immunoassay*

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Monitoring Pharmacodynamic ResponseH2AX Immunofluorescence Assay

SOP340523 H2AX IFA for Tumor Biopsy Slides

SOP340504 Preparation of Cytospin Slides

SOP340522 Tumor Frozen Needle Biopsy Preparation

SOP340524 H2AX Immunofluorescence Assay for Cytospin Slides

SOP340533 Image Capture and Analysis of Tumor Biopsy Slides from H2AX IFA

SOP340514 PBMC Isolation and Fixation for Cytospin Slides

SOP340507 Tumor Frozen Needle Biopsy Collection and Handling

SOP340525 Image Capture and Analysis of Cytospin Slides

Tumor Biopsy

Blood

Specimen Collection Specimen Preparation Pharmacodynamic Testing

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PAR Immunoassay

H2AX Immunofluorescence Assay

Analysis of PAR and H2AX in Patient Tumor Biopsies

•Paired tumor biopsies analyzed from 3 patients before Veliparib (topotecan alone) and after Veliparib + topotecan combination treatment.

•There is currently insufficient data to determine if there is a correlation between PAR and H2AX response in tumors following Veliparib + topotecan treatment.

Dose Level 1 Dose Level -1 Dose Level -3

Dose Level -1 Dose Level -3

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H2AX Immunofluorescence Assay

PAR and H2AX response in PBMCs at the Veliparib + Topotecan MTD

•There is an inverse correlation between PAR and H2AX response in PBMCs following Veliparib + topotecan combination treatment at dose level -3 (MTD).

•H2AX responders are defined as patients with >2-fold increase in %H2AX nuclear area positive pre-Veliparib treatment.

PAR Immunoassay

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Veliparib Potentiates Topotecan-Mediated DNA Damage in PBMCs

• PAR inhibition of >50% represents a statistically signifcant pharmacodynamic response to Veliparib (arrow).

• Increased H2AX levels are associated with PARP inhibition at Dose Level -3

97.8% average PAR reduction in H2AX responders*

52.3% average PAR reduction in non-responders

PBMC specimens 2 h after ABT-888 + Topotecan

*

*

*

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Conclusions

• Increased H2AX levels in PBMCs were associated with PARP inhibition such that H2AX responders had almost 2-fold more PAR reduction than non-responders.

• PARP inhibition by Veliparib potentiates topotecan-mediated DNA damage, as measured in PBMCs.

• Additional tumor biopsy samples are needed to determine if the same effect can be seen in tumor biopsies.

Clinical Trial Summary • A total of 24 patients with refractory solid tumors and lymphomas were enrolled in the

Veliparib + topotecan combination Phase I clinical trial. • Significant myelosuppression was observed, necessitating dose reductions and

changes in schedule. • All of the observed toxicities were expected from topotecan and were managed

without complications.• The MTD has been established and stable disease has been documented in several

patients.

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Veliparib Early-Phase Clinical Trials:Correlative Studies Using PAR and/or H2AX Assays

CTEP #Veliparib in Combination With:

Clinical TrialPrincipal Investigator

7981 Topotecan ABT-888 and Topotecan in Treating Patients With Advanced or Refractory Solid Tumors, Lymphoma, or Chronic Lymphocytic Leukemia Kummar

8329 TopotecanABT-888 and Topotecan Hydrochloride in Treating Patients With Advanced Solid Tumors or Relapsed or Refractory Ovarian Epithelial Cancer or Primary Peritoneal Cancer

Menefee

7968 Topotecan, CarboplatinABT-888 and Topotecan With or Without Carboplatin in Treating Patients With Relapsed or Refractory Acute Leukemia, High-Risk Myelodysplasia, or Aggressive Myeloproliferative Disorders

Karp

7967 Carboplatin, PaclitaxelABT-888, Carboplatin, and Paclitaxel in Treating Patients With Advanced Solid Cancer Ramalingam

7977 IrinotecanIrinotecan and ABT-888 in Treating Patients With Metastatic or Unresectable Cancer LoRusso

8275 Cyclophosphamide OralABT-888 and Cyclophosphamide in Treating Patients With Solid Tumors or Lymphoma That Did Not Respond to Previous Therapy Kummar

7998Cyclophosphamide IV and Doxorubicin

ABT-888 and Cyclophosphamide With Versus Without Doxorubicin in Treating Patients With Metastatic or Unresectable Solid Tumors or Non-Hodgkin Lymphoma

Tan

8282 Single AgentABT-888 in Treating Patients With Malignant Solid Tumors That Did Not Respond to Previous Therapy Puhalla

8472Single Agent and Mitomycin-C Combination

ABT-888 With or Without Mitomycin in Treating Patients With Metastatic, Unresectable, or Recurrent Solid Tumors Villalona-Calero

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Acknowledgements

Yiping ZhangRavithat PutvatanaWilliam YutzyLan TranYvonne A. EvrardKaren Gray Tiziano DiPaoloMelanie SimpsonRobert J. KindersRalph E. ParchmentNCI Phase 0 Clinical Trials Team

Shivaani KummarAlice ChenLarry RubinsteinMelinda HollingsheadAnthony MurgoChristophe RedonWilliam BonnerYves PommierJerry CollinsJoseph E. TomaszewskiJames H. Doroshow

NCI CTEP Veliparib Clinical Trial Principal Investigators, Patients, and Teams