Vincent L. Giranda

Phase I Study of Veliparib (ABT-888) Combined with Cisplatin and Vinorelbine in Advanced Triple-Negative Breast Cancer and/or BRCA Mutation–Associated Breast Cancer

Purpose: Cisplatin is synergistic with vinorelbine and the PARP inhibitor veliparib, and has antineoplastic activity in triple-negative breast cancer (TNBC) and BRCA mutation–associated breast cancer. This phase I study assessed veliparib with cisplatin and vinorelbine. Experimental Design: A 3+3 dose-escalation design evaluated veliparib administered twice daily for 14 days with cisplatin (75 mg/m2 day 1) and vinorelbine (25 mg/m2 days 1, 8) every 21 days, for 6 to 10 cycles, followed by veliparib monotherapy. Pharmacokinetics, measurement of poly(ADP-ribose) in peripheral blood mononuclear cells, and preliminary efficacy were assessed. IHC and gene-expression profiling were evaluated as potential predictors of response. Results: Forty-five patients enrolled in nine dose cohorts plus five in an expansion cohort at the highest dose level and recommended phase II dose, 300 mg twice daily. The MTD of veliparib was not reached. Neutropenia (36%), anemia (30%), and thrombocytopenia (12%) were the most common grade 3/4 adverse events. Best overall response for 48 patients was radiologic response with 9-week confirmation for 17 (35%; 2 complete, 15 partial), and stable disease for 21 (44%). Germline BRCA mutation presence versus absence was associated with 6-month progression-free survival [PFS; 10 of 14 (71%) vs. 8 of 27 (30%), mid-P = 0.01]. Median PFS for all 50 patients was 5.5 months (95% confidence interval, 4.1–6.7). Conclusions: Veliparib at 300 mg twice daily combined with cisplatin and vinorelbine is well tolerated with encouraging response rates. A phase II randomized trial is planned to assess veliparibs contribution to cisplatin chemotherapy in metastatic TNBC and BRCA mutation–associated breast cancer. Clin Cancer Res; 22(12); 2855–64. ©2016 AACR.

A phase I trial of veliparib (ABT-888) and temozolomide in children with recurrent CNS tumors: a pediatric brain tumor consortium report.

BACKGROUND A phase I trial of veliparib (ABT-888), an oral poly(ADP-ribose) polymerase (PARP) inhibitor, and temozolomide (TMZ) was conducted in children with recurrent brain tumors to (i) estimate the maximum tolerated doses (MTDs) or recommended phase II doses (RP2Ds) of veliparib and TMZ; (ii) describe the toxicities of this regimen; and (iii) evaluate the plasma pharmacokinetic parameters and extent of PARP inhibition in peripheral blood mononuclear cells (PBMCs) following veliparib. METHODS TMZ was given once daily and veliparib twice daily for 5 days every 28 days. Veliparib concentrations and poly(ADP-ribose) (PAR) levels in PBMCs were measured on days 1 and 4. Analysis of pharmacokinetic and PBMC PAR levels were performed twice during study conduct to rationally guide dose modifications and to determine biologically optimal MTD/RP2D. RESULTS Twenty-nine evaluable patients were enrolled. Myelosuppression (grade 4 neutropenia and thrombocytopenia) were dose limiting. The RP2Ds are veliparib 25 mg/m(2) b.i.d. and TMZ 135 mg/m(2)/d. Only 2 out of 12 patients treated at RP2Ds experienced dose-limiting toxicities. Although no objective response was observed, 4 patients had stable disease >6 months in duration, including 1 with glioblastoma multiforme and 1 with ependymoma. At the RP2D of veliparib, pediatric pharmacokinetic parameters were similar to those in adults. CONCLUSIONS Veliparib and TMZ at the RP2D were well tolerated in children with recurrent brain tumors. A phase I/II trial to evaluate the tolerability and efficacy of veliparib, TMZ, and radiation in children with newly diagnosed brainstem gliomas is in progress.

A randomized Phase II study of veliparib with temozolomide or carboplatin/paclitaxel versus placebo with carboplatin/paclitaxel in BRCA1/2 metastatic breast cancer: design and rationale

Veliparib is an orally administered poly(ADP-ribose) polymerase inhibitor that is being studied in Phase I–III clinical trials, including Phase III studies in non-small-cell lung cancer, ovarian cancer and breast cancer. Tumor cells with deleterious BRCA1 or BRCA2 mutations are deficient in homologous recombination DNA repair and are intrinsically sensitive to platinum therapy and poly(ADP-ribose) polymerase inhibitors. We describe herein the design and rationale of a Phase II trial investigating whether the addition of veliparib to temozolomide or carboplatin/paclitaxel provides clinical benefit over carboplatin/paclitaxel with placebo in patients with locally recurrent or metastatic breast cancer harboring a deleterious BRCA1 or BRCA2 germline mutation (Trial registration: EudraCT 2011-002913-12, NCT01506609).

Outcome of BRCA 1/2-mutated (BRCA+) and triple-negative, BRCA wild type (BRCA-wt) breast cancer patients in a phase I study of single-agent veliparib (V).

135 Background: Veliparib (V) (ABT-888) is an oral, potent inhibitor of PARP 1/2. PARP inhibitors have preclinical and clinical efficacy in BRCA+ malignancies. There are genotypic and phenotypic similarities between BRCA+ cancers, serous ovarian cancer and basal-like breast cancer and we postulated that these tumors types may be similarly sensitive to single-agent PARP inhibition. This study sought to establish the maximum tolerated dose (MTD), dose -limiting toxicities (DLT), pharmacokinetic and pharmocodynamic properties, and preliminary efficacy of chronically-dosed V in 2 cohorts of patients, BRCA+ and BRCA-wt (consisting of serous ovarian cancer and triple-negative breast cancer (TNBC). METHODS A 3+3 dose escalation phase I trial was performed. Nine dose levels (DL) were planned, and dose escalation started at 50 mg BID to a maximum of 500 mg BID to determine a maximum tolerated dose (MTD) and recommended phase II dose (RP2D). V was administered orally continuously on a 28 day cycle. BRCA+ and BRCA-wt patients were enrolled in 2 separate cohorts with 2 separate escalations. RESULTS 98 (70 BRCA+ and 28 BRCA-wt) pts have been enrolled. The maximum administered dose (MAD) was 500mg BID and the MTD/RP2D is 400mg BID for both cohorts. 59 BRCA+ pts and 24 BRCA-wt pts (21 TNBC and 3 ovary) were evaluable for response. ORR was defined as CR+PR and clinical benefit rate (CBR) as CR+PR+SD > 6 months. Results are summarized in the table. CONCLUSIONS There is evidence of anti-tumor activity with V comparable to that of other PARP inhibitors in the BRCA+ population. There was indication of dose responsiveness with greater activity in this population at higher doses. There is less activity in the mostly TNBC, BRCA-wt population, although there was evidence of benefit in a small number of patients. Ongoing tissue correlative studies will help to identify potential mechanisms of sensitivity and resistance. CLINICAL TRIAL INFORMATION NCT00892736. [Table: see text].

Phase III randomized, placebo-controlled trial of carboplatin (C) and paclitaxel (P) with/without veliparib (ABT-888) in HER2- BRCA-associated locally advanced or metastatic breast cancer (BC).

155 Background: BRCA-mutated tumors are more susceptible to platinum therapy and PARP inhibitors due to underlying defects in homologous recombination repair of DNA damage. In preclinical models the potent oral PARP1/2 inhibitor veliparib was shown to enhance sensitivity to C and to have single-agent activity in BRCA+ cell lines. Phase 1 trials suggest promising antitumor activity and acceptable toxicity of veliparib plus C/P in triple-negative BC (Puhalla et al. Cancer Res 2012;72:PD09-06) and single-agent activity of veliparib in BRCA+ BC (Somlo et al. J Clin Oncol 2014;32:abstr. 1021). This phase III trial assesses efficacy and toxicity of veliparib plus C/P vs C/P alone in patients with HER2- BRCA-associated locally advanced or metastatic BC (NCT02163694). METHODS Phase III randomized, double-blind, placebo-controlled, multicenter trial. Eligible patients (female or male; ≥ 18 years) have HER2-metastatic/locally advanced unresectable BC with (suspected) deleterious BRCA1/2 germline mutations and received 2 or fewer prior lines of DNA-damaging chemotherapy for metastatic BC. In addition, patients must have received ≤ 1 prior line of platinum therapy (any setting) without progression within 12 months of completing treatment. Patients are randomized 2:1 to C/P with veliparib or C/P with placebo, stratified by estrogen and/or progesterone receptor expression, prior platinum therapy, and central nervous system metastases. Veliparib (120 mg p.o. BID) or placebo will be given on Days -2 to 5, C (AUC 6 mg/mL/min i.v.) on Day 1, and P (80 mg/m2i.v.) on Days 1, 8, and 15 (21-day cycles). Treatment continues until unacceptable toxicity or progressive disease (PD). Patients in the placebo arm who discontinue due to PD are eligible for crossover to veliparib monotherapy. The primary objective is to assess if the addition of veliparib to C/P increases progression-free survival; additional objectives include evaluation of overall survival, clinical benefit rate, objective response rate, quality of life, and safety. Enrollment began in July 2014 with a planned sample size of 270 patients. CLINICAL TRIAL INFORMATION NCT02163694.

Pilot study of veliparib (ABT-888) with temozolomide (TMZ) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).

224 Background: Castration-resistant PC tumors exhibit increased PARP activity (critical enzymes for DNA damage repair). Veliparib is a novel, oral, potent inhibitor of PARP-1 and PARP-2. Preclinically, resistance to oral TMZ treatment in the PC3-Luc prostate cancer mouse model was reversed when mice were treated with veliparib. Based on the synergistic interaction, we evaluated the efficacy and safety of veliparib + TMZ in mCRPC pts. METHODS Eligible pts had mCRPC, PSA>2 ng/mL, progressed on at least one docetaxel based therapy and adequate organ function. Pts received veliparib 40 mg BID Days (D) 1-7 and TMZ D1-5 in 28D cycle (C) until disease progression (PD) or unacceptable toxicities. Tumor response was assessed every 8 weeks. PRIMARY OBJECTIVE Efficacy based on rate of PSA decline of 30% or greater. Secondary objectives: safety, RECIST objective response rate, progression-free survival (PFS), overall survival (OS) and biomarker analyses. A sample size of 25 pts provided 76% power to differentiate between PSA response rates of 5 and 20% at 1-sided type I error rate of 0.1. RESULTS 26 pts were enrolled; median age 67 years [55, 81]; median baseline PSA 107 ng/ml (6.9, 4584.4); 7/26 (27%) had 2 prior therapies. Median Cs of veliparib + TMZ received were 2 (range 1-9). Most frequent treatment related adverse events (AE) were fatigue (50%), nausea (38%) and constipation (23%). Grade 3/4 AEs in >10% of pts was thrombocytopenia (15%). All pts are off therapy. 25 pts were PSA response evaluable; 2 pts had a confirmed PSA response; 1 pt had a 37% decrease in PSA while the other pt had a 96% decrease in PSA and a 40% reduction in tumor size. 4/25 pts had stable disease for a minimum of 4 months (m). Median PFS was 2.1 m [95% CI: 1.8, 3.9]; 11/26 pts have died with median OS of 9.1 m [95% CI: 5.5, 11.7]. There was a negative correlation between change from baseline in circulating tumor cells and PFS. CONCLUSIONS Veliparib + TMZ were well tolerated with evidence of some activity. Due to lack of activity of TMZ in CRPC,veliparib-induced potentiation of TMZ may not be clinically significant. Other combinations will be explored with higher doses of veliparib. Biomarker data will be presented.