Tesaro's injected chemo nausea med Varubi can cause anaphylaxis, company warns

Tesaro issued a safety warning for Varubi after patients experienced anaphylaxis and anaphylactic shock.

Only a few months after winning FDA approval for its injectable version of chemo nausea med Varubi, Tesaro is having to reach out to doctors to update them with a safety warning for the drug. Some patients have experienced anaphylaxis and anaphylactic shock shortly after receiving the injected version of the drug.

Tesaro announced the label update Friday after working with the FDA on the changes. The drugmaker's sales force will update doctors on the label change, and the company is also sending a letter to doctors detailing the side effects.

First licensed in 2015, Varubi is approved to prevent nausea and vomiting in patients who are being treated with emetogenic chemotherapy. The drugmaker won approval for its IV form last October.

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The drug hasn't taken off in a big way commercially, however. For the first nine months of 2017, Tesaro reported $7.4 million in Varubi sales. Its competitor, Merck's Emend, brought in $413 million for the same period. Tesaro only launched the IV formulation in November, so it remains to be seen how much the new form will add to the biotech's top line going forward.

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The company says about 7,000 doses of the IV version of Varubi have been administered so far in the rollout. Leerink analysts have projected the drug will reach $343 million in sales by 2026.

Before winning FDA approval for the IV form, Tesaro had to work through a complete response letter from the FDA requesting info about manufacturing by contractor partners.

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Varubi is one of two licensed meds for the Boston-area biotech. The company also markets Zejula, a PARP inhibitor in competition with Clovis Oncology's Rubraca and AstraZeneca's Lynparza.

Tesaro's shares were down about 3% Friday on the news. U.S. markets were closed Monday.