• Early Phase 2 data suggest Clovis Oncology’s targeted cancer drug Rubraca may work as a maintenance therapy for certain pancreatic cancer patients, according to a study presentation Tuesday at the American Association of Cancer Research annual meeting in Atlanta.
• Results from the study, which was investigator initiated, showed treatment with the PARP inhibitor resulted in a median progression-free survival of 9.1 months and an overall response rate of 37%. Clovis said it is evaluating a clinical and regulatory path forward for Rubraca in the tumor type. 
• The single-arm study is set up to enroll 42 patients to test whether Rubraca could serve as a less toxic maintenance option following chemotherapy. So far, 30 patients have been recruited, although only data from 19 were ready for analysis. Eligibility was limited to advanced pancreatic cancer patients with pathogenic mutations in either the BRCA or PALB2 genes and who have received chemotherapy.

For pancreatic cancer, the advance of PARP inhibitors like Rubraca (rucaparib) could provide an alternative to chemotherapy, currently the standard of care for the particularly difficult-to-treat tumor type. 

“While this subgroup of pancreatic cancer patients respond well to platinum-based chemotherapy, prolonged treatment leads to cumulative toxicity, so this approach often becomes unsustainable,” said the study’s lead author, Kim Reiss Binder, a hematologist-oncologist at the University of Pennsylvania, in an April 2 statement.

Writing in an April 2 note to clients, Andrew Berens, an analyst with SVB Leerink, called the data further validation of the PARP class in cancers beyond ovarian and breast. 

While the results show some potential for Rubraca in the first-line maintenance setting for advanced pancreatic cancer, Clovis still trails the leader of the PARP inhibitor class, AstraZeneca’s Lynparza (olaparib).

In February, the British pharmaceutical giant released its own positive topline results for Lynparza as a first-line maintenance treatment for certain advanced pancreatic cancers, teeing up a regulatory filing for later this year. That Phase 3 study was a randomized, double-blinded test against placebo, whereas the Phase 2 study of Rubraca was set up as single-arm. 

The patient populations between the two trials varied only slightly. While Lynparza’s trial focused on metastatic pancreatic cancers after first-line chemotherapy responses who had germline BRCA mutations, Clovis also included mutations in the PALB2 gene. Only 2 of the 19 evaluable patients in the preliminary study results had such a mutation, however. 

Given the overlap with AstraZeneca’s later-stage study, Berens stated it was unclear if Clovis would try for an accelerated approval for Rubraca. 

Rubraca isn’t just trailing Lynparza in pancreatic cancer. AstraZeneca’s drug, which is co-commercialized with Merck & Co., leads the PARP class in both approved indications and sales, also outstripping GlaxoSmithKline’s recently acquired PARP inhibitor, Zejula (niraparib).

The Clovis study started in mid-2017 and primary completion is expected in June 2021, according to a federal clinical trials database. Company CEO Patrick Mahaffy said in a statement he hopes to have more details on Rubraca’s future path in pancreatic cancer later this year.

After opening relatively flat Tuesday, Clovis shares rose about 2% by noon. Despite that small bump, the company’s stock is still down about 50% over the past 12 months.