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Tesaro loses out as rival AstraZeneca ovarian cancer med gains

March 14, 2017
  • Newly released data showing dramatic efficacy from AstraZeneca’s PARP inhibitor Lynparza (olaparib) in ovarian cancer set off a chain reaction in markets, pushing shares of rival Tesaro down 11% while the British pharma saw its stock climb by about 1%.
  • Treatment with Lynparza, which is already approved on an accelerated basis in the U.S. for BRCA-mutated ovarian cancer, reduced the risk of disease progression by 70% compared to placebo, according to an investigator-assessed analysis of the SOLO-2 study.
  • The results look set to boost the competitive profile of AstraZeneca’s drug, potentially damaging the commercial prospects of Tesaro’s experimental niraparib, another PARP inhibitor. News of the data boosted Clovis Oncology, however, which secured approval for Rubraca (rucaparib) in third-line ovarian cancer late last year.

Markets have paid close attention to the PARP inhibitors from Tesaro and Clovis, sizing up the profiles of each to see whether either biotech might wrest market share away from AstraZeneca’s Lynparza, initially approved in 2014.

Results from Tesaro released at the annual meeting of the European Society for Medical Oncology last October showed niraparib extended median PFS by nearly 16 months and reduced the risk of disease progression by 73%.

Shares in the Danish biotech soared then, but AstraZeneca’s new data throws cold water on Tesaro’s hope of having a best-in-class PARP inhibitor.

AstraZeneca’s study tested Lynparza as a maintenance therapy for patients with germline BRCA-mutated relapsed ovarian cancer. Median PFS for those patients treated with Lynparza hit 19.1 months, compared to 5.5 months for those on placebo, according to an investigator’s analysis.

Supporting data from a Blinded Independent Central Review analysis registered even more impressive figures: a median PFS of 30.2 months for Lynparza versus a similar 5.5 months for placebo.

While the studies are not directly comparable, AstraZeneca’s SOLO-2 results suggest Lynparza has a similar efficacy profile. Results should support an approval in earlier lines of treatment — Lynparza is currently only recommended for use in heavily pre-treated ovarian cancer patients.

Nearly 37% of patients on Lynparza reported Grade 3 or higher adverse events, compared to 18.2% of patients on placebo. Anemia, neutropenia and thrombocytopenia were the most commonly reported hematological adverse events..

Compared to Tesaro’s niraparib, Lynparza showed much lower rates of Grade 3 or higher neutropenia or thrombocytopenia events.

AstraZeneca also introduced a new 300mg twice-daily tablet formulation that lowers the pill burden for patients on Lynparza from 16 capsules to four tablets.

While Tesaro stock plunged, shares in Clovis gained more than 10%, suggesting investors see greater value from Clovis’ already approved Rubraca.

For AstraZeneca, the results boost the company’s fortunes in oncology. But soon-to-be forthcoming results from the Phase 3 MYSTIC study of durvalumab and tremelimumb will be the true litmus test of the British pharma’s prospects in the space.


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