May 8 (Reuters) - The U.S. Food and Drug Administration

has approved Verastem's ( VSTM ) combination therapy for

patients with a rare type of ovarian cancer who have received

prior treatment, the regulator said on Thursday.

The combination drug, branded as Avmapki Fakzynja Co-pack,

will be available in one week, the company said. Pricing details

for it were not available.

The FDA decision marks the first and only approval for a

drug to treat adults with this form of cancer, called low-grade

serous ovarian cancer with a mutation in a gene known as KRAS.

About 6,000-8,000 women in the U.S. and 80,000 worldwide are

living with this disease, according to the company.

The cancer disproportionately affects younger women and has

poor response rates to chemotherapy.

Approval for the drug was based on data from a mid-stage

trial of 57 patients who were treated with at least one prior

therapy. In the trial, Verastem's ( VSTM ) drug significantly improved

patients' response rate while being generally well tolerated.

Share of the company were halted in mid-day trading.