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Tesaro shares climb as nausea drug hits phase III endpoints

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By Michael Fitzhugh
Staff Writer

Investors drove Tesaro Inc. shares up 21 percent Monday (NASDAQ:TSRO) on news that the company hit both its primary and secondary endpoints in a phase III trial of rolapitant, its top hope for breaking into the $1.5 billion U.S. market for drugs preventing chemotherapy-induced nausea and vomiting (CINV).

Merck & Co. Inc.'s Emend (aprepitant) leads that market today, with the only FDA-approved drug in rolapitant's class, NK-1 receptor antagonists. Rolapitant is the company's lead candidate and, following this third and last phase III study of the drug, Tesaro plans to file an FDA new drug application (NDA) for the oral drug by mid-2014. An NDA for an intravenous-administration will likely follow in early 2015, Tesaro president and co-founder Mary Lynne Hedley told BioWorld Today.

Tesaro, of Waltham, Mass., showed that rolapitant hit its primary endpoint of complete response, the prevention of vomiting and elimination of need for rescue medication to fight nausea, in the period between one day and five days following treatment. The drug also hit its key secondary endpoints of achieving complete response during the entire five days immediately following treatment.

But it was rolapitant's ability to eliminate significant nausea for patients during all five days post-treatment that caught Deutsche Bank research analyst Robyn Karnauskas' eye. She issued a '"Buy" rating on Tesaro shares Monday, highlighting that secondary endpoint as giving rolapitant an edge over Merck's Emend and suggesting it could help Tesaro eventually gain at least 40 percent of the CINV therapy market in the U.S.

Tesaro's Hedley noted that no head-to-head studies have been conducted comparing rolapitant and Emend on nausea alone, but that "if you talk to physicians and patients, you'll find that nausea is a real unmet need. If we're able to provide some relief in that realm, that could be be significant for rolapitant."

More than 70 percent of patients receiving chemotherapy experience at least some degree of chemotherapy-induced nausea and vomiting (CINV.) If not prevented, it can delay continued treatment and lead to unwanted weight loss, dehydration, malnutrition and hospitalization.

The phase III study of rolapitant was an international, multicenter, randomized, double-blind, active-controlled study. It enrolled 532 cancer patients receiving cisplatin-based chemotherapy regimens at a dose equal to or greater than 60 mg/m2. Patients in the study were randomized to receive either the control, a 5-HT3 receptor antagonist, plus dexamethasone, or 200 mg of oral rolapitant plus control.

Tesaro said rolapitant's adverse event profile remains consistent with what the company had seen in previous studies, including constipation, headache, fatigue and dizziness.

The company will present detailed results of this trial, together with the results of its prior two phase III trials at the upcoming American Society of Clinical Oncology annual meeting.

Although Tesaro's clinical development efforts have been focused primarily on its oral formulation of rolapitant, it's currently testing an intravenous formulation in a phase I trial. The outcome of that study and those after it will be significant for Tesaro, since I.V.-administered therapies for CINV make up 80 percent of the market, relative to the 20 percent for oral treatments.

If rolapitant is successfully commercialized, it could also face competition from Helsinn Group, of Lugano, Switzerland, and Mundipharma Pte. Ltd., of Singapore, which have filed an NDA for their oral combination of the NK1 antagonist netupitant and palonosetron, a second-generation 5-HT3 receptor antagonist. (See BioWorld Today, Dec. 24, 2013.)

Rolapitant could face yet more competition if a competitor develops an I.V. formulation of its CINV treatment and prevention product, such as Innopharma Inc. is working to do.

Tesaro acquired rolapitant from Miami-based Opko Health Inc. for $121 million, including milestones, double-digit tiered royalties and a 10 percent equity position in Tesaro. Upon acceptance of the rolapitant NDA by the FDA, it will owe Opko a milestone payment of $5 million. In addition, it has obligations to make additional milestone payments to Opko of up to $85 million if specified levels of annual net sales of rolapitant are achieved.

While Tesaro is dependent on the future success of rolapitant, it has plenty of other bets on the table. The company is advancing niraparib, a phase III PARP inhibitor, against ovarian cancer, BRCA-positive breast cancer and Ewing's sarcoma. It is also pushing ahead with a phase I/II trial of TSR-011, its oral inhibitor of both anaplastic lymphoma kinase, or ALK, and tropomyosin-related kinase, or TRK, in ALK-positive non-small-cell lung cancer.

Adding to its pipeline, Tesaro agreed in March to pay $17 million up front for rights to three cancer antibody programs developed by Anaptysbio Inc. It could pay Anaptysbio as much as $108 million more per target as Tesaro takes each program beyond preclinical development. (See BioWorld Today, March 14, 2014.)

The company expects to begin trials of TSR-042, the lead anti-PD-1 antibody in-licensed as part of the agreement, in mid-2015. Tesaro reported having $180.2 million in cash as of March 31, 2014.

The company's stock gained $5.04 Monday, closing at $29.05.