- New positive data for Clovis Oncology's ovarian cancer treatment Rubraca (rucaparib) could position the biotech to secure an expanded label for the PARP inhibitor, potentially improving its competitive standing versus rival drugs from AstraZeneca and Tesaro, Inc.
- Rubraca — currently approved as a third-line treatment for ovarian cancer patients with a specific mutation known as BRCA — significantly improved progression-free survival compared to placebo when given as maintenance therapy following initial treatment with platinum-based chemotherapy.
- The strong results, which came from a Phase 3 confirmatory study, mean Rubraca could pose a direct challenge to Tesaro's recently approved Zejula (niraparib). Tesaro stock fell in Monday trading, while shares of Clovis rose by more than 40% in value.
Clovis, AstraZeneca and Tesaro are all competing to broaden the market opportunity for their respective PARP inhibitors, a class of drugs which works somewhat counter intuitively by blocking a DNA repair mechanism.
AstraZeneca's Lynparza (olaparib) and Clovis' Rubraca were first OK'd specifically for ovarian cancer patients whose tumors had defective BRCA genes, while Zejula won approval from the Food and Drug Administration regardless of BRCA mutation status.
Clovis' 564-patient ARIEL 3 study was designed to expand Rubraca's indication to all women with platinum-sensitive ovarian cancer, and support use of the drug as a maintenance therapy.
To that end, the Boulder, Colorado-based biotech plans to submit a supplemental New Drug Application to the FDA within the next four months.
On an intent-to-treat basis, Rubraca improved median progression-free survival (PFS) by 5.4 months compared to placebo, reducing the relative risk of disease worsening or death by 64%.
Rubraca also hit on two other primary endpoints, extending PFS in patients whose tumors tested positive for BRCA mutations or were HRD-positive. The drug's benefit was clearest in the BRCA subgroup, with a median PFS of 16.6 months for those in the treatment arm versus 5.4 months for placebo.
Notably, some patients who had previously experienced a partial response while on initial chemotherapy saw an improved response from Rubraca, suggesting a benefit beyond prevention of disease recurrence.
AstraZeneca expects to win approval for Lynparza in the maintenance setting by the third quarter of this year based on the SOLO-2 data.
So far, PARP inhibitors are only approved for use in ovarian cancer. But the next battle for market position could be in other cancer types. AstraZneeca recently unveiled positive data for Lynparza in HER2-negative, BRCA-mutated breast cancer. And Tesaro and Clovis are both conducting studies of their respective PARP inhibitors in cancers such as triple-negative breast cancer and prostate cancer.
While Clovis shares surged on news of the ARIEL-3 data, the biotech disclosed in a securities filing that it had entered into a settlement agreement to resolve a lawsuit alleging the company misled investors about the potential of another cancer drug called rociletinib.
Clovis will recognize a $142 million charge to earnings in the second quarter of 2017 in connection with the settlement.