Gilead Sciences Inc. is paying Arcus Bioscience Inc. $175 million up front, shelling out a $200 million equity investment, and pledging potentially $1.6 billion or more in the form of R&D support, opt-in cash and milestone payments.

The decade-long cancer immunotherapy deal is designed to develop and commercialize current as well as future candidates in Hayward, Calif.-based Arcus’ pipeline. There’s plenty to work with. Arcus not only has immune system-targeting prospects but also those taking aim at cell-intrinsic pathways in cancer. The roster includes antibody compounds meant for immune checkpoint receptors, including PD-1 and TIGIT. At the clinical stage, Arcus has four immuno-oncology programs, with six undergoing preclinical work. A key part of Arcus’ strategy is the development of intra-portfolio combinations that include small molecules and antibodies.

Under the terms, the pair will co-commercialize Gilead-optioned programs in the U.S. with equal profit-sharing, with Arcus in line for double-digit royalties outside the country. Arcus has agreed to keep researching new targets independently, and is providing Foster City, Calif.-based Gilead with opt-in rights to all programs in Arcus’ pipeline.

Specifically, Arcus is eligible to bank up to $1.225 billion in opt-in and milestone payments with respect to its current clinical candidates. The pact grants Gilead immediate rights to zimberelimab, as well as opt-in rights to all other current Arcus clinical prospects, which include AB-154, AB-928 and AB-680, upon payment of a fee that ranges from $200 million to $275 million per program, after the delivery of a qualifying data package.

If Gilead opts in to the AB-154 program, Arcus could collect as much as $500 million, should goals be met related to U.S. regulatory approval. Gilead would pay $150 million per program if opt-in rights are exercised on other programs that emerge from Arcus over the next 10 years. Ongoing R&D support will be provided to the tune of up to $400 million over the collaboration term, and Gilead has the right to appoint two people to Arcus’ board once the contract is made final, which is expected to happen in the third quarter of this year.

SVB Leerink analyst Geoffrey Porges said in a report that the deal, rumored since mid-April, is “largely what we expected” and expands Gilead’s reach while allowing Arcus to maintain its independence. Shares of Arcus (NYSE:RCUS) were trading at $30.51, down $3.03. Gilead (NASDAQ:GILD) was selling for $73.92, up 75 cents.