San Diego biotech MEI Pharma signed a major deal with Swiss pharmaceutical group Helsinn that could be worth up to $464 million.

The deal licenses MEI’s drug, Pracinostat, to Helsinn under an exclusive worldwide agreement to develop and commercialize the drug for acute myeloid leukemia and other possible indications. Helsinn will also be responsible for funding the global development of Pracinostat.

As compensation for such rights, MEI will get $20 million right away, including a $15 million upfront payment and a $5 million payment upon dosing of the first patient in the upcoming Phase 3 trial of Pracinostat in newly diagnosed acute myeloid leukemia patients.

MEI Pharma will also be eligible to receive up to $444 million in potential development, regulatory, and sales-based milestone payments, along with additional tiered royalty payments in certain territories.

MEI’s stock (Nasdaq: MEIP) is up over 20 percent on the news, trading at just under $2 per share. MEI is a microcap public company in San Diego, with a current market cap of about $73 million.