Abstract B102: A phase 2, open-label study of the PARP inhibitor rucaparib in patients with pancreatic cancer and a known deleterious BRCA mutation
Authors: Domchek Susan M. , McWilliams Robert , Hendifar Andrew , Shroff Rachna T. , Leichman Lawrence , Epelbaum Ron , Geva Ravit , Kim George , Alberts Steven R. , Wolff Robert A. , Allen Andrew , Giordano Heidi , Raponi Mitch , Isaacson Jeff , Rolfe Lindsey , Biankin Andrew , Vonderheide Robert H. 
Published: October 2015

Background: Despite the recent progress made with front-line treatment for advanced pancreatic cancer (PC), most patients (pts) will either relapse or be refractory to treatment. Others may not even be eligible due to the toxicity profile of the available options or due to clinical deterioration. Once the disease progresses following front-line treatment, there is no accepted standard of care. Treatment options are clearly needed for patients with refractory disease.

Approximately 5% of unselected PC pts, 10% of PC patients of Ashkenazi Jewish descent, and up to 19% of familial PC cases, harbor a germline BRCA mutation. Though less well characterized to date, somatic BRCA mutations also appear to play a significant role in PC. Clinical data have shown that pts with BRCA-mutant (BRCAmut) tumors, including those with PC, respond to treatment with a PARP inhibitor (PARPi). Early data suggest that other genomic characteristics may be surrogate biomarkers of homologous recombination deficiency (HRD) and define a larger group of responders than just BRCA mutation(s) alone.

Rucaparib, an oral PARPi, is being developed for treatment of cancers associated with HRD due to a BRCA mutation or other homologous recombination pathway defect. Rucaparib has a desirable PK profile, is well tolerated, and has demonstrated clinical activity (RECIST and/or CA-125 responses) in patients with BRCAmut pancreatic, ovarian, or breast cancer in an ongoing Phase 1/2 study (NCT01482715). Three studies are currently ongoing in ovarian cancer and a trial in BRCAmut pancreatic cancer is now planned. The clinical activity of PARPi, including rucaparib, in BRCAmut PC, combined with the paucity of active 2nd-line therapies, support evaluation of rucaparib in PC pts with a BRCA mutation.

Methods: Study CO-338-023 (NCT02042378) is a single-arm, open-label Phase 2 trial of continuous monotherapy rucaparib in up to 100 pts with pancreatic ductal adenocarcinoma (or related subtype) who are known to harbor a deleterious BRCA mutation (germline or somatic). Pts must have received at least 1, but no more than 2, prior regimens for locally advanced or metastatic disease and have relapsed / progressive disease confirmed by radiologic assessment, or are no longer able to tolerate chemotherapy due to toxicity, and radiologic assessment confirms stable or progressive disease. Other key inclusion criteria include measurable disease, ECOG Performance Status 0 or 1, and adequate organ function. Pts with endocrine tumors or who received prior PARPi treatment are excluded. Pts will take 600 mg BID rucaparib continuously and be evaluated for safety every 2–4 wks, disease status (CT scans, CA19–9) every 4–8 wks until disease progression, and then for survival every 4 wks. Blood and archival tumor tissue (if available) will be collected from all pts.

The primary endpoint is ORR by RECIST v1.1. Key secondary endpoints include duration of response, PFS, OS, and safety. Exploratory analyses include gene sequence and structural rearrangements of tumor DNA and evaluation of circulating tumor DNA. A group sequential interim monitoring plan will be implemented to stop the study early for either superior efficacy or futility. Interim analyses will occur after every 10th patient enrolled has sufficient disease assessment data available. If robust activity is observed in the BRCAmut PC population, the trial may be broadened to include PC pts with HRD due to other than a BRCA mutation.

The trial will be open to enrollment at clinical sites in the US and Israel in 2Q 2014.

Citation Format: Susan M. Domchek, Robert McWilliams, Andrew Hendifar, Rachna T. Shroff, Lawrence Leichman, Ron Epelbaum, Ravit Geva, George Kim, Steven R. Alberts, Robert A. Wolff, Andrew Allen, Heidi Giordano, Mitch Raponi, Jeff Isaacson, Lindsey Rolfe, Andrew Biankin, Robert H. Vonderheide. A phase 2, open-label study of the PARP inhibitor rucaparib in patients with pancreatic cancer and a known deleterious BRCA mutation. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B102.