Gilead Sciences (NASDAQ: GILD) announced Tuesday it's paying $300 million for a 49.9% ownership stake in Tizona Therapeutics and an option to acquire the company outright later for up to $1.25 billion in fees and potential milestone payments. The deal provides the privately owned company with financing to support the development of TTX-080, a potential first-in-class immunotherapy targeting HLA-G, an immune checkpoint molecule expressed in multiple tumor types. A phase 1 study of HLA-G as monotherapy and in combination with existing treatments is set to begin enrolling patients this quarter. IMAGE SOURCE: GETTY IMAGES. If successful, TTX-080 could offer an alternative treatment for patients who don't respond to checkpoint inhibitors targeting the immune checkpoint PD-1, including the blockbuster drugs Opdivo and Keytruda. TTX-080 may enhance the efficacy of PD-1 inhibitors, suggesting there's also a potential pathway to improving the standard of care in eligible solid tumor cancer patients. The biotech giant will be able to exercise its option to acquire the remaining equity of Tizona Therapeutics "following the completion of Phase 1b studies for TTX-080, or earlier." Management expects this deal to close in the third quarter, after Tizona has spun-out its other drug in development, TTX-030, as a separate company. An anti-CD39 antibody, TTX-030 is being developed in partnership with AbbVie (NYSE: ABBV). 10 stocks we like better than Gilead SciencesWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Gilead Sciences wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of June 2, 2020 Todd Campbell owns shares of Gilead Sciences. His clients may have positions in the companies mentioned. The Motley Fool owns shares of and recommends Gilead Sciences. The Motley Fool has a disclosure policy.Source