An Update on Our Sickle Cell Program

Today, Flagship Pioneering, Cellarity’s founder, announced Etcelera, a new company that will take the Cellarity platform forward alongside the platforms of Etiome and Empress Therapeutics. Read the Flagship press release here.

Cellarity’s sickle cell program, CLY-124, is not part of this combination. It will continue in the clinic as a standalone company that retains the Cellarity name, it’s current leadership, led by Dr. John H. Leaman, with a dedicated team and resources focused on bringing this therapy to patients.

Since June 2025, we have been steadily advancing the clinical development of CLY-124, a first-in-class oral noncytotoxic fetal hemoglobin inducer therapy for the treatment of sickle cell disease (SCD). CLY-124 is the product of our platform, which identified an entirely new mechanism for turning on the production of disease-correcting fetal hemoglobin, designed a compound in silico to act on that pathway, and developed it through preclinical evaluation. We are enormously proud of that accomplishment and motivated by the potential impact this molecule may have for patients around the world.

Initial data from the clinical trial suggest that CLY-124 results in a meaningful elevation of fetal hemoglobin and fetal reticulocytes and exhibits an acceptable safety profile that can be attributed to our non-cytotoxic approach.

In the coming months, we expect to complete additional Phase 1 28-day multiple ascending dose cohorts, and to file a protocol amendment with the FDA to enable 3-month treatment of patients with Sickle Cell Disease in both Kenya, the U.S.

Over the past year, it became clear that successful clinical development of CLY-124 requires a dedicated team and resources, and creating a standalone company is the best way to provide them.

We are enthusiastic about the path forward for both companies, including the opportunity for continued collaboration as we pursue a shared purpose of discovering and developing new medicines for patients.