Tesaro's (TSRO) Zejula, an oral, once-daily poly (ADP-ribose) polymerase (PARP) inhibitor, was approved by the FDA for the maintenance treatment of women with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy. Tesaro anticipates launching Zejula in the United States in late April.
Zejula is the first PARP inhibitor to be approved by the FDA that does not require BRCA mutation or other biomarker testing. In December, Clovis (CLVS) received FDA approval of Rubraca, its PARP inhibitor for the monotherapy treatment of advanced ovarian cancer in women with deleterious germline or somatic BRCA mutations treated with two or more chemotherapies.
Two weeks ago, AstraZeneca (AZN) reported positive Phase 3 data for its PARP inhibitor Lynparza. The comparable data took some wind out of Tesaro's sails. While TSRO is viewed as a takeout candidate for its prized oncology asset, the scarcity value was somewhat diminished by AZN's positive data.
The broad label that Tesaro received is a negative for Myriad Genetics' (MYGN) diagnostic tool that won't be required.
Tesaro also announced a substantial expansion of its niraparib clinical development program in combination with an anti-PD-1 antibody (e.g. Merck's Keytruda or Bristol-Myers' Opdivo). The company is implementing its plans to initiate registration strategies in the settings of metastatic ovarian, breast and lung cancers, with intent to replace chemotherpay for the first-line treatment.
We have seen a sell the news reaction this morning. Tesaro has given up all its gains after gapping up ~6% into its 50-day moving averages. While the approval was expected, it came earlier than the June deadline.
Tesaro would be a fairly large acquisition for a large pharma/biotech company. Its enterprise value is just under $8 billion.