ASCO: Forty Seven announces $115M IPO alongside first-in-human CD47 data

Red blood cells
Forty Seven's 5F9 antibody demonstrated an objective response rate of 50% in non-Hodgkin’s lymphoma when combined with Rituxan, and also showed partial responses as a single agent in ovarian cancer. (Wikimedia Commons)

In the 48 hours after filing for a $115 million IPO, immuno-oncology developer Forty Seven unveiled first-in-human data for its CD47-targeting monoclonal antibody at the American Society of Clinical Oncology’s annual meeting in Chicago, alongside pledges to advance it into phase 2 studies.

The company’s proof-of-concept data came from two early-phase clinical trials of the agent 5F9: when given with Rituxan (rituximab) in non-Hodgkin’s lymphoma, the combination demonstrated an overall objective response rate of 50% and a complete response rate of 36%.

Meanwhile, a pharmacokinetics and pharmacodynamics study in patients with advanced solid tumors showed single-agent activity against ovarian cancer. 5F9’s blocking of CD47 switches off the signals cancer cells use to avoid being attacked by the immune system.

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“Together, the data presented at ASCO reveal an encouraging clinical profile for 5F9, suggesting that blocking CD47 can render difficult-to-treat tumors susceptible to phagocytosis,” Chris Takimoto, Forty Seven’s chief medical officer, said in a statement.

“We are committed to exploring 5F9’s full potential and are now advancing a broad clinical development program at the recommended priming and phase 2 dose and schedule, including multiple trials across a range of tumors and treatment modalities,” Takimoto said. The antibody is currently being studied in six clinical trials in solid tumors, acute myeloid leukemia, NHL and colorectal carcinoma.

Back on Wall Street, the Menlo Park, California-based company plans to list on the Nasdaq with the symbol FTSV; pricing terms and the number of shares were not disclosed.

The Stanford University spinout was co-founded in 2015 by Irv Weissman, director of the university’s Institute for Stem Cell Biology and Regenerative Medicine, who helped discover that cancer stem cells express CD47, the so-called “don’t eat me” signal, during development.

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

The first half of Forty Seven’s ongoing phase 1b/2 trial in relapsed/refractory NHL enrolled 22 participants, including patients with diffuse large B-cell lymphoma and follicular lymphoma, with 95% considered refractory to Rituxan treatment. 5F9 was generally well-tolerated at all doses, with the most common adverse event an expected effect on red blood cells causing a reversible anemia. There was one patient discontinuation.

In DLBCL, the ORR was 40%, with one-third of patients demonstrating a complete response. In FL, the ORR reached 71%, with 43% of patients achieving a CR. Only one patient has progressed after a median follow-up of over six months, the company said. 5F9 was previously granted a Fast Track designation by the FDA in these indications.

The phase 1 PK and PD trial enrolled 62 participants at a variety of doses and schedules, including patients with heavily treated colorectal, ovarian, salivary, breast and other solid tumors. In ovarian cancer, two patients, following six previous treatment regimens, demonstrated confirmed partial responses, with one’s PR lasting over six months.

RELATED: Forty Seven lines up Roche as second partner for CD47 cancer immunotherapy

“These early clinical responses for 5F9 as a single agent, coupled with strong preclinical data, support Forty Seven's combination strategy in ovarian cancer, including the recently initiated phase 1b trial combining 5F9 with the anti-PD-L1 inhibitor, avelumab, under the company’s existing collaboration with Merck KGaA,” said study investigator Amita Patnaik, co-director of clinical research at South Texas Accelerated Research Therapeutics.

Forty Seven partnered with Merck in November 2017 to study 5F9 in combination with Bavencio (avelumab) in a phase 1b ovarian cancer trial, as well as with Eli Lilly and Merck’s Erbitux (cetuximab) in colorectal cancer. The company is also collaborating with Roche’s Genentech unit, to study 5F9 with the PD-L1 inhibitor Tecentriq (atezolizumab).