Forty Seven raises another $75M to expand I-O trial slate

Hu5F9-G4 is designed to do for macrophages—white blood cells that gobble up other cells—what Merck’s Keytruda and Bristol-Myers Squibb’s Opdivo do for T cells. (Librepath/CC BY-SA 3.0)

Forty Seven has raised $75 million, bringing its total haul to date up to $150 million. The series B round equips the Stanford University spinout to expand trials of its CD47-targeted approach to dialing up phagocytosis of cancer cells.

New backer Wellington Management led the round with the support of Clarus, Lightspeed Venture Partners, Sutter Hill Ventures and GV, the four VCs that drove Forty Seven to its $75 million series A 20 months ago. Forty Seven used that cash to license immuno-oncology programs from Stanford and build on the early clinical work initiated by the university.

Now, Forty Seven has the means to expand beyond its current slate of five phase 1b and phase 1b/2 clinical trials. The new trials will pair lead candidate Hu5F9-G4 to T-cell checkpoint inhibitors.

The combination could unleash a powerful two-front immune system attack on tumors. Hu5F9-G4 is designed to do for macrophages—white blood cells that gobble up other cells—what Merck’s Keytruda and Bristol-Myers Squibb’s Opdivo do for T cells. On paper, the combination will take the breaks off the anti-tumor activities of both T cells and macrophages.

Forty Seven is rolling out the checkpoint inhibitor combination trials on the back of studies that are assessing Hu5F9-G4 as a monotherapy and in partnership with existing cancer drugs. 

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Since pulling in the series A funds, Forty Seven has kicked off clinical trials testing Hu5F9-G4 with Vidaza in hematological malignancies, Erbitux in solid tumors and Rituxan in B-cell non-Hodgkin's lymphoma. Another two clinical trials started by Stanford prior to the licensing deal are testing the drug as a monotherapy in solid tumors and hematological malignancies.

Stanford initiated the first of those trials in 2014 in the wake of papers by Irv Weissman, M.D., and his colleagues that identified CD47 as a potentially pivotal molecule in the fight against cancer. The excitement about CD47 stemmed from its near-ubiquitous use by cancer cells to stop macrophages from attacking. If a drug could remove this defence, macrophages could join immune attacks on tumors.

The Stanford scientists weren’t alone in recognizing the therapeutic potential of their research. In the years since they moved Hu5F9-G4 into the clinic, Alexo Therapeutics, Celgene and Trillium Therapeutics have all begun testing CD47 drugs in humans. But, with five trials underway and more to come, Forty Seven has used its first-mover advantage to establish itself at the front of the pack.