After expanding its partnership with Syndax $SNDX earlier this week on their lead drug, Genentech has beefed up their pipeline of PD-L1 combos with a fresh pact with Stanford spinout Forty Seven.

The biotech put out word that Genentech will combine their two checkpoint drugs for use against acute myeloid leukemia and bladder cancer, with the big Roche subsidiary sponsoring the studies.

Tecentriq was the fourth PD-1/L1 checkpoint to hit the market, taking one foot off the brake of an immune response targeting cancer cells. Forty Seven, the brainchild of Stanford’s legendary investigator Irv Weissman, targets the “don’t eat me” signal cancer cells employ to hide out from a macrophage assault. The drug works by binding Hu5F9-G4 to CD47.

Forty Seven was one of the unusual biotechs out there, getting plenty of support from CIRM to go into Phase I before the company was set up and funded.

The number of combo studies using PD-1/L1 has exploded since the arrival of Merck’s Keytruda and Bristol-Myers Squibb’s Opdivo, leading some to wonder if there’s much thought going into the rationale behind all of them. Genentech, though, seems happy with its strategy this week.

Craig Gibbs

“There is a large unmet medical need for new therapies for AML and bladder cancer patients, particularly those who are elderly or have compromised organ function and are not able to withstand the side-effects of chemotherapy,” said Forty Seven business chief Craig Gibbs. “We are excited to evaluate these novel combinations in collaboration with a global leader in oncology.”