Tesaro's PARP inhibitor approved in ovarian cancer
- Starting off a busy week of expected approvals, the Food and Drug Administration gave an early OK to Tesaro’s PARP inhibitor niraparib for maintenance treatment in patients with recurrent epithelial ovarian, fallopian tube or primary peritoneal cancer who are in complete or partial response to platinum-based chemotherapy.
- The drug, which will be marketed under the name Zejula, is the first PARP inhibitor to be approved that does not require testing for the BRCA mutation or other biomarkers.
- The company also announced that it is unlikely to fulfill enrollment for the BRAVO study, which is testing niraparib in breast cancer patients with germline BRCA mutations, due the availability of other PARP inhibitors — complicating enrolling for the chemotherapy control arm of the study.
Three months ahead of its prescription fee action date, Tesaro scored approval for Zejula and joined the fast-growing field. The company said during a March 27 call with investors that it expects the drug will "become an important treatment at first recurrence and beyond."
Tesaro secured a broad label across patients both with and without BRCA mutated cancers. AstraZeneca's Lynparza (olaparib) and Clovis Oncology's Rubraca (rucaparib), two rival drugs already on the market, both received accelerated approval only for those patients with BRCA mutations.
Approval of Zejula was based on the 553-patient NOVA study, which tested the drug as a single once-daily oral therapy against a placebo and separated patients based on their germline BRCA mutation status. The trial showed that patients with the BRCA mutation had a progression-free survival (PFS) of 21 months compared to 5.5 months for those taking the placebo. Meanwhile, in patients without the germline BRCA mutation, the PFS was 9.3 months compared with 3.9 months for those non-mutation patients on placebo.
The company did not announce a price for the drug, but expects to launch at the end of April. When pressed for pricing details on the call, Tesaro CEO Lonnie Moulder did add that Tesaro so far has had a "substantial" number of meetings with payers accounting for roughly 80% of covered lives in the U.S.
A sales force and medical staff of 175 reps is ready to go, the company said on the call.
Tesaro will have its work cut out for it, though, to quickly grow market share as AstraZeneca and Clovis work to expand labels of their own drugs.
Recent results from AstraZeneca's SOLO-2 study, announced in mid-March, showed that the AstraZeneca drug had a PFS of 19.1 months in patients with the BRCA mutation, compared to 5.5 months for those on placebo. An independent analysis of the data showed an even better response beyond 30 months.
Tesaro will continue its pursuit of approval for niraparib in other cancer types and earlier lines of therapy. On that note, it expanded two of its other ovarian cancer clinical trials to test niraparib in combination with a PD-1 inhibitor, as well as a trial testing niraparib in combination with Avastin (bevacizumab). The hope is that this data will allow Zejula to be used as a first-line therapy and even replace chemotherapy as standard of care.
However, Tesaro's good news was lined with a clinical setback in the BRAVO study, which was studying niraparib in breast cancer patients with germline BRCA mutations. The biotech had previously expected the study to be registrational for that indication, but an interim analysis revealed that heavy drop-outs in the chemotherapy control arm likely meant any data would not be interpretable.
Company COO Mary Lynne Hedley attributed the drop-out to the availability of PARP inhibitors, leading patients assigned to the chemo arm to seek treatment with one of the approved agents. Some investigators also switched patients on chemo to another PARP inhibitor after disease progression was confirmed, further eating away at the chemo cohort.
In light of the difficulties with BRAVO, Tesaro plans to focus more heavily on triple-negative breast cancer (TNBC) — a market roughly twice the size of BRCA mutated breast cancer. A Phase 3 trial pairing niraparib with an unspecified anti-PD-1 antibody will be added to Tesaro's development program in advanced TNBC, along with an existing Phase 2 trial combining niraparib with Keytruda (pembrolizumab).
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