Imago BioSciences’ Bomedemstat Demonstrates Continued Encouraging Clinical Activity in Phase 2 Data for Treatment of Essential Thrombocythemia and Myelofibrosis at EHA 2021 Virtual Congress

Imago BioSciences, Inc. (“Imago”), a clinical stage biopharmaceutical company discovering new medicines for the treatment of myeloproliferative neoplasms (MPNs), today provided updates on two Phase 2 clinical trials of bomedemstat, one in patients with essential thrombocythemia (ET) and, the second in patients with advanced myelofibrosis (MF). The data were presented in two e-poster presentations during the 26^th European Hematology Association Virtual Congress (EHA 2021), taking place June 9-17, 2021.

Poster title: A Phase 2 Study of the LSD1 Inhibitor IMG-7289 (Bomedemstat) in Patients with Essential Thrombocythemia

The presented data show that bomedemstat was generally well-tolerated by patients with ET and demonstrated encouraging clinical activity as a monotherapy, showing symptomatic improvement in patients with significant MPN symptoms. Of the 12 patients dosed with bomedemstat for more than six weeks, 83% displayed substantial improvements in platelet count reduction, achieving platelets ≤ 400x10⁹/L. Of the 10 patients entering the study with elevated white blood cell counts and evaluable at 12 weeks, 80% saw these counts fall within normal ranges. These improvements were achieved while maintaining stable hemoglobin levels. There were no dose limiting toxicities, no safety signals per Safety Advisory Board and one serious adverse event that was deemed unrelated.

“These encouraging data show that bomedemstat was well-tolerated and has the potential to bring meaningful clinical benefits for patients with essential thrombocythemia,” said Wan-Jen Hong, M.D., chief medical officer of Imago BioSciences. “We are excited about these preliminary results from our lead asset, and look forward to completing enrollment of this study in order to lay the groundwork for a planned pivotal study in essential thrombocythemia.”

Poster title: A Phase 2 Study of the LSD1 Inhibitor IMG-7289 (Bomedemstat) in Patients with Advanced Myelofibrosis

The presented data from an ongoing Phase 2 study indicated that bomedemstat as a monotherapy for patients with advanced MF offered a distinct clinical benefit profile, and was generally well-tolerated among participants. Of the 16 patients evaluable at 24 weeks, 94% showed improvements in total symptom scores (TSS), with a reduction of 50% or greater in almost a third of this subset. In an analysis of 34 patients evaluated for mutant allele frequencies (MAFs), MAFs decreased in 44% of patients and were stable in 47%, with no new mutations in up to 660 days of follow-up. Of the 18 patients evaluable for splenomegaly at 24 weeks, 89% had a reduction in spleen volume, with that of one patient decreasing by more than 35%. There were no dose limiting toxicities, no safety signals per Safety Advisory Board, and no progression to acute myeloid leukemia (AML).

“These updated clinical results reveal that bomedemstat continues to offer distinct clinical benefits for patients with advanced MF, showing overall improvement in total symptom scores, spleen volumes and anemia,” said Wan-Jen Hong, M.D., chief medical officer of Imago BioSciences. “The study is now fully enrolled, so we look forward to sharing our cumulative data as we continue to advance this investigational program for patients who have few therapeutic alternatives.”

Poster presentations are available on the EHA Virtual Congress platform. The posters will also be available on the Imago website here.

About Imago BioSciences

Imago BioSciences is a clinical-stage biopharmaceutical company discovering and developing novel small molecule product candidates that target lysine-specific demethylase 1 (LSD1), an enzyme that plays a central role in the production of blood cells in the bone marrow. Imago is focused on improving the quality and length of life for patients with cancer and bone marrow diseases. Bomedemstat, an orally available, small molecule inhibitor of LSD1, is the lead product candidate discovered by Imago for the treatment of certain myeloproliferative neoplasms (MPNs), a family of related, chronic cancers of the bone marrow. Imago is evaluating Bomedemstat as a potentially disease-modifying therapy in two Phase 2 clinical trials for the treatment of essential thrombocythemia (ET) and myelofibrosis (MF). Bomedemstat has U.S. FDA Orphan Drug and Fast Track Designation for the treatment of ET and MF, Orphan Drug Designation for treatment of AML, and PRIME designation by the European Medicines Agency for the treatment of MF. Imago is backed by leading private, crossover and strategic investors including a fund managed by Blackstone Life Sciences, Frazier Healthcare Partners, Omega Funds, Farallon Capital Management, L.L.C., funds and accounts advised by T. Rowe Price Associates, Inc., and funds and accounts managed by Blackrock Advisors, LLC. The company is based in South San Francisco, California.

To learn more, visit:

www.imagobio.com, www.myelofibrosisclinicalstudy.com, www.etclinicalstudy.com and follow us on Twitter @ImagoBioRx, Facebook, LinkedIn and YouTube.

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