Tesaro earns CHMP thumbs-up for Zejula as three-way PARP race heats up

Zejula is on track to be the first once-daily PARP inhibitor approved in Europe to treat ovarian cancer patients, regardless of their BRCA status.

When Tesaro entered the PARP inhibitor market in April with its contender, Zejula, it had a clear leg up on its two major competitors, Clovis Oncology’s Rubraca and AstraZeneca’s Lynparza. Tesaro’s drug was the only one to boast FDA approval as a maintenance treatment for women with ovarian cancer, regardless of their BRCA status. Then AZ won the same approval and it looked as if Tesaro would lose its market-leading position.

Now Tesaro is in a strong position to win another regulatory victory that could boost its standing in the market, this one from Europe. Today the Swiss company announced that European Medicines Agency's (EMA) Committee for Medicinal Products for Human Use (CHMP) is recommending that Zejula be approved as a maintenance treatment for ovarian cancer patients who had previously responded to platinum-based therapy.

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If that approval is granted, Zejula (niraparib) will be the first once-daily, oral PARP inhibitor cleared in Europe for patients regardless of their BRCA status. The CHMP opinion will now be passed to the European Commission, which will decide whether or not to grant the approval. Tesaro says it is preparing to launch the drug in Europe at year-end, pending the approval.

It was just one month ago that Tesaro seemed to be in danger of losing its lead in the ovarian cancer market. In mid-August, the FDA cleared AZ’s new oral formulation of Lynparza, while simultaneously approving the drug as a maintenance treatment and granting the company permission to market it to patients with or without BRCA mutations. Clovis is seeking a similar approval, and Tesaro analysts were so worried they predicted Tesaro would end up with only one-third of the total market in the end.

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But during Tesaro’s second-quarter earnings call in August, CEO Lonnie Moulder outlined results from Zejula’s U.S. launch that showed just how important the broad approval has been. In the second quarter, about 1,500 patients started on the drug, he said, and only half of them had BRCA mutations. The refill rate continued to rise, he added, accounting for half of the units shipped in the last month of the quarter. In June, he said, Zejula had 60% of the PARP inhibitor market.

Sales of Zejula came in at $26 million for the quarter. Analysts are predicting the drug’s sales will grow to $1.9 billion annually by 2022.

Still, investors have been fretting over the competition. Tesaro has trumpeted results from its large phase 3 trial, NOVA, which showed a median progression-free survival of 15.5 months in patients with BRCA mutations. In BRCA-negative patients, the drug also delayed disease progression. But during the second-quarter conference call, one analyst suggested the data sets on the competing drugs were so similar that Zejula would be in danger of losing its lead—particularly when Clovis’ drug goes generic.

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Countered Mary Lynne Headley, Tesaro’s chief operating officer, “Clovis themselves have indicated that they did not or were not able to surpass the NOVA data with any of the specific endpoints that were looked at. From our perspective, the data from the NOVA trial are very strong and demonstrate across all of the population a very significant benefit.”

Investors seem to be taking heart in the CHMP’s positive opinion. Tesaro’s shares rose more than 2% in pre-market trading to $115.24.