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The U.S. Food and Drug Administration has granted Orphan Drug status to STM 434 for the treatment of patients with ovarian cancer. STM 434, a fusion protein that binds Activin A and other ligands of the ActR2B receptor, has been shown to be involved in the growth and proliferation of ovarian cancer and other tumors.

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The Orphan Drug designation-to encourage development of drugs in the diagnosis, prevention, or treatment of a medical condition affecting fewer than 200,000 people in the U.S.-grants a product market exclusivity for a seven-year period if the sponsor complies with certain FDA specifications, as well as tax credits and prescription drug user fee waivers. The designation does not, though, shorten the duration of the regulatory review and approval process.


STM 434, made by Atara Biotherapeutics, Inc., is currently being evaluated in a three-part Phase I clinical study of patients with advanced ovarian cancer, as well as other solid tumors. The first part of the study is dose escalation in patients with advanced solid tumors; the second part is a monotherapy dose expansion in patients with advanced ovarian cancer, including clear cell and granulosa cell tumors; and the third part is designed to evaluate STM 434 in combination with chemotherapy in patients with advanced ovarian cancer.


Initial data from the first part of the study is expected in 2016, according to a news release from the manufacturer.