Japanese pharmaceutical company Astellas Pharma Inc. and San Francisco based Medivation Inc. have signed a global partnership for the development and marketing of the US firm's experimental prostate cancer treatment.

Astellas is to make an immediate cash payment of $110-million to Medivation, including being eligible for $335-million in development and regulatory milestone payments, together with $320-million in commercial milestones, news which saw Medivation shares rise 8.2% to $28.25 in pre-market trading.

Presently, MDV3100 is being studied in a recently begun Phase 3 clinical trial on men with castration-resistant prostate cancer, previously treated with docetaxel-based chemotherapy. The castration-resistant form is also known as hormone-refractory prostate cancer, which has few treatment options and a 12-months survival rate.

Prostate cancer is estimated to affect about 1 million men in the U.S.

Both the companies are planning additional studies of the drug in late and early stage prostate cancer. The drug will be jointly sold and developed in the U.S., while Astellas taking the lead outside U.S., will pay a double-digit royalty that increases on the achievement of certain sales levels.

Last year, Medivation and Pfizer Inc. signed a partnership, including $225-million in upfront cash and $500-million in additional payments, for the development and co-marketing of Dimebon, a potential Alzheimer's disease treatment, which is currently being tested in a 12-month Phase III trial, while a 350-patient study has recently begun on Huntington's disease.

Medivation Chief Executive David Hung calls Astellas an ideal partner for MDV3100, because of its experience in selling benign prostatic hyperplasia drug Flomax (tamsulosin) and over-active bladder product Vesicare (solefinacin succinate), 'so that will give us great entry into the urology market,' Hung added.