Astellas Pharma Inc. (TSE: 4503, President and CEO: Kenji Yasukawa, Ph.D., "Astellas") today announced that gonadotrophin-releasing hormone (GnRH) receptor antagonist, Gonax®received approval for partial changes for the additional dosage and administration of Gonax® for the treatment of prostate cancer at 12-week intervals, and obtained manufacturing and marketing authorization for Gonax® 240 mg in Japan.

Gonax® is a GnRH receptor antagonist with a subcutaneously injectable formulation. Astellas acquired exclusive development and commercialization rights of Gonax® for the use of prostate cancer treatment in Japan from Ferring Pharmaceuticals in January 2006, and launched Gonax® for the indication of prostate cancer in Japan in October 2012.

GnRH is a hormone synthesized and released from the hypothalamus in the brain and is involved in the production of the male hormone testosterone thorough binding to the GnRH receptors in the pituitary gland. Although testosterone is an important hormone that plays a central role in the maintenance of male function, it also stimulates prostate cancer to grow and to spread out and in result, often aggravates symptoms in prostate cancer patients. Gonax® competitively inhibits the binding of GnRH to the GnRH receptors and controls the growth of prostate cancer by suppressing the testosterone. 

Astellas believes that adding the maintenance dose of Gonax® 480 mg at 12-week intervals to the maintenance dose of Gonax® 80 mg at 4-week intervals will improve convenience for patients and reduce the burden on patients and further contribute to the treatment of prostate cancer.

Astellas reflected the impact from this approval in its financial forecasts of the current fiscal year ending March 31, 2019.