Tesaro's ovarian cancer drug shows benefit in late-stage trial

J – Tesaro Inc said its ovarian cancer drug met the main goal of prolonging survival in patients, without the disease worsening, in a late-stage trial, sending its shares up 84 percent in premarket trading.

The drug, niraparib, improved progression-free survival in certain ovarian cancer patients.

About 22,000 women are diagnosed with ovarian cancer in the United States every year, and nearly 80 percent are diagnosed after it has progressed to a severe stage.

The trial which enrolled more than 500 patients, included subjects some of whom had a BRCA gene mutation.

BRCA is a tumor suppressing gene, and ovarian cancer patients who carry this gene mutation are more treatable because they respond better to chemotherapy.

In patients with BRCA mutation, progression-free survival for patients treated with niraparib was 21 months, compared to 5.5 months for those on a placebo.

In patients without the BRCA mutation, who are relatively more difficult to treat, the progression free survival for patients treated with the drug was 9.3 months compared to 3.9 months, for those on placebo.

Tesaro shares rose to $68.50 in premarket trading on Wednesday. (Reporting by Amrutha Penumudi in Bengaluru; Editing by Shounak Dasgupta)