News Releases

Forty Seven Inc. to Present New Preclinical Data on 5F9 at the 60th American Society of Hematology (ASH) Annual Meeting

November 1, 2018 at 9:00 AM EDT

 -- 5F9 Priming Dose Results in CD47 Pruning, Removing CD47 from Surface of Red Blood Cells to Mitigate Risk of Anemia --
 -- 5F9 Demonstrates Synergy in Combination with Azacitidine in Acute Myeloid Leukemia (AML) Models --

MENLO PARK, Calif., Nov. 01, 2018 (GLOBE NEWSWIRE) -- Forty Seven Inc. (NASDAQ:FTSV) today announced that new preclinical data elucidating the mechanism of action of its proprietary priming dose strategy for 5F9 will be presented in a poster session at the 60th American Society of Hematology (ASH) Annual Meeting in San Diego, California, December 1-4, 2018. Also in a poster session, the Company will present preclinical data supporting the combination of 5F9 and azacitidine for the treatment of acute myeloid leukemia (AML). 5F9 is Forty Seven’s lead antibody against CD47, which is currently being evaluated for the treatment of solid tumors, AML, non-Hodgkin’s lymphoma, ovarian cancer and colorectal cancer.

The presentation on Forty Seven’s proprietary 5F9 priming and maintenance dosing strategy will include preclinical data providing additional mechanistic insight into why this dosing strategy mitigates on-target anemia caused by the clearance of aged red blood cells (RBCs).  This study demonstrates that the initial priming dose of 5F9 results in a near complete loss of CD47 on surviving, younger RBCs – a phenomenon termed CD47 pruning. As a result, these cells are less susceptible to phagocytosis, contributing to a decreased risk of CD47 antibody-induced anemia during subsequent maintenance dosing. These findings are RBC-specific, as white blood cells and AML bone marrow blasts did not exhibit the same pruning effect, suggesting that CD47 pruning does not affect the therapeutic efficacy of 5F9.

The presentation on 5F9 plus azacitidine, a standard of care therapy for AML, will include preclinical data demonstrating that the combination increases the phagocytic elimination of AML blast cells by human macrophages in vitro, enhances clearance of AML in vivo, and prolongs survival compared to single-agent treatment with either 5F9 or azacitidine alone.

"We are pleased to unveil these preclinical results, which provide important insights supporting our proprietary priming dose strategy and underscore our belief in 5F9 as a safe and tolerable option for patients," said Chris Takimoto, M.D., Ph.D., F.A.C.P., Chief Medical Officer of Forty Seven, Inc. “We are focused on advancing the clinical development of 5F9 and we believe there is a strong and compelling scientific rationale for its use in the treatment of multiple cancers. To that end, we are especially excited to present preclinical data demonstrating the potential synergies of 5F9 and azacitidine, which is hypothesized to induce pro-phagocytic signals on the surface of tumor cells. We believe these data further support our combination strategy in hematologic cancers, including our ongoing Phase 1b clinical trial in patients with AML and high-risk myelodysplastic syndrome.”

The accepted abstracts are listed below and are now available online on the ASH website:

RBC-Specific CD47 Pruning Confers Protection and Underlies the Transient Anemia in Patients Treated with Anti-CD47 Antibody 5F9
Presentation Date & Time:Sunday, December 2, 2018, 6:00 p.m.8:00 p.m. PT (9:00 p.m.11:00 p.m. ET)
Poster Session Title: 101. Red Cells and Erythropoiesis, Structure and Function, Metabolism, and Survival, Excluding Iron: Poster II
Abstract Number: 2327
Location: San Diego Convention Center, Hall GH

Combination Treatment with 5F9 and Azacitidine Enhances Phagocytic Elimination of Acute Myeloid Leukemia
Presentation Date & Time:Sunday, December 2, 2018, 6:00 p.m.8:00 p.m. PT (9:00 p.m.11:00 p.m. ET)
Poster Session Title: 616. Acute Myeloid Leukemia: Novel Therapy, excluding Transplantation: Poster II
Abstract Number: 2729
Location: San Diego Convention Center, Hall GH

About 5F9:
5F9 is a monoclonal antibody against CD47 that is designed to interfere with recognition of CD47 by the SIRPα receptor on macrophages, thus blocking the “don’t eat me” signal used by cancer cells to avoid being ingested by macrophages. Forty Seven, Inc. is initially developing 5F9, an investigational medicine, for the treatment of patients with solid tumors, acute myeloid leukemia, non-Hodgkin’s lymphoma, ovarian cancer and colorectal cancer. 5F9 has been granted Fast Track designation by the U.S. Food and Drug Administration for the treatment of relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma, two forms of B-cell non-Hodgkin’s lymphoma.

Forward Looking Statements:
Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "expect," "anticipate," "estimate," "intend," “potential,” and similar expressions (as well as other words or expressions referencing future events, conditions, or circumstances) are intended to identify forward-looking statements. These statements include those related to the effectiveness of the Company’s dosing strategy to mitigate on-target anemia; the potential of 5F9 as a safe and tolerable treatment option for patients; the effectiveness of 5F9 for the treatment of AML and high-risk myelodysplastic syndrome single-agent treatment and in combination with azacitidine.  Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. The product candidates that Forty Seven develops may not progress through clinical development or receive required regulatory approvals within expected timelines or at all. In addition, clinical trials may not confirm any safety, potency or other product characteristics described or assumed in this press release. Such product candidates may not be beneficial to patients or successfully commercialized. The failure to meet expectations with respect to any of the foregoing matters may have a negative effect on Forty Seven's stock price. Additional information concerning these and other risk factors affecting Forty Seven's business can be found in Forty Seven's periodic filings with the Securities and Exchange Commission at These forward-looking statements are not guarantees of future performance and speak only as of the date hereof, and, except as required by law, Forty Seven disclaims any obligation to update these forward-looking statements to reflect future events or circumstances.

About Forty Seven Inc.:
Forty Seven, Inc. is a clinical-stage immuno-oncology company that is developing therapies targeting cancer immune evasion pathways based on technology licensed from Stanford University. Forty Seven’s lead program, 5F9, is a monoclonal antibody against the CD47 receptor, a “don’t eat me” signal that cancer cells commandeer to avoid being ingested by macrophages. This antibody is currently being evaluated in six clinical studies in patients with solid tumors, acute myeloid leukemia, non-Hodgkin’s lymphoma, ovarian cancer and colorectal carcinoma.

For more information please visit or contact

For journalist inquiries please contact Sarah Plumridge at or phone (312) 506-5218.

For investor inquiries please contact Hannah Deresiewicz at Stern Investor Relations Inc. at or phone (212) 362-1200. 


Source: Forty Seven, Inc.

Email Alerts
Contact IR
Investor FAQs
RSS Feeds