Clovis Oncology’s Rubraca has been something of an also-ran among PARP inhibitors when it comes to market share, but a first-in-class filing in prostate cancer could give the product a boost.
The FDA has just started a six-month priority review of Rubraca (rucaparib), with a verdict due by 15 May, as a monotherapy for adults with BRCA1/2-mutated recurrent, metastatic castrate-resistant prostate cancer (CRPC). Mutations in the BRCA1/2 genes are the most common defects in patients with mCRPC.
Clovis is seeking approval for Rubraca in patients who have received a prior round of taxane-based chemotherapy, as well as at least one of the newer hormonal agents, such as Johnson & Johnson’s Zytiga (abiraterone) or Pfizer’s Xtandi (enzalutamide).
It’s currently used as a maintenance treatment for ovarian, fallopian tube and primary peritoneal cancer after chemotherapy, and as a third-line or later therapy for relapsed patients with BRCA mutations in these cancers.
If approved in prostate cancer, Rubraca would be the first targeted therapy for this type of solid tumour.
The filing means that Rubraca has beaten rivals such as AstraZeneca/Merck & Co’s market-leading Lynparza (olaparib), GlaxoSmithKline/Janssen’s Zejula (niraparib) and Pfizer’s new entrant Talzenna (talazoparib) to the punch in prostate cancer, a potentially lucrative new indication for the PARP class.
First approval could give Clovis an opportunity to build familiarity with its brand among clinicians treating CRPC before its big pharma rivals reach the market, although its rivals are hot on its heels.
AZ and Merck already have a successful phase 3 trial in hand for Lynparza in second-line CRPC and have said they plan to file for approval in this indication in the first half of 2020, while GSK/J&J have also reported positive pivotal data for Zejula in CRPC and are thought to be also planning regulatory submissions this year.
J&J has exclusive rights to Zejula in prostate cancer under the terms of an agreement signed with the drug’s develop Tesaro ahead of its $5.1bn acquisition by GSK last year.
All three of the PARP inhibitors have been awarded a breakthrough designation from the FDA in prostate cancer, reflecting the urgent need for new therapies to treat the disease.
Clovis’ marketing application is based on the results from the TRITON trials programme, in particular the TRITON2 study which showed a 44% response rate with Rubraca in BRCA-mutated CRPC, and a 52% prostate-specific antigen (PSA) response.
A combination trial of Rubraca plus Bristol-Myers Squibb’s checkpoint inhibitor Opdivo (nivolumab) – called CheckMate 9KD – is also ongoing with initial results due later this year.