Omisirge, FDA Approves First Cellular Therapy for Severe Aplastic Anemia

On December 8, 2025, the Food and Drug Administration (FDA) authorized Omisirge (omidubicel-onlv) as the first hematopoietic stem cell transplant (HSCT) therapy intended for patients with severe aplastic anemia (SAA): the indication extends to adults and pediatric patients six years of age and older when a compatible donor is not available and following reduced intensity conditioning.

Omisirge is a product derived from umbilical cord blood whose stem cells have been chemically enhanced with nicotinamide (a form of vitamin B3) prior to infusion. The goal of treatment is to restore hematopoietic function in patients with SAA, reducing some of the historical limitations associated with the use of unmodified cord blood, such as delayed hematopoietic recovery and increased risk of infections.

The new approval follows data from a prospective, open-label, single-arm study conducted in patients six years of age and older with SAA. In the efficacy population, 12 of 14 patients achieved early and sustained neutrophil engraftment , with median time to neutrophil recovery of 11 days (range 7–20 days). The FDA highlighted this result as a key element for reducing recovery times after transplantation.

The most frequent adverse events reported include febrile neutropenia , viral and bacterial infections, hyperglycemia , immune thrombocytopenia, and pneumonia; autoimmune cytopenias were observed in 25% of patients. Product safety therefore requires careful post-transplant surveillance, particularly for infectious risk and autoimmune manifestations that may develop in the months following treatment.

From a regulatory perspective, the Omisirge application received Orphan Drug and Priority Review designations; approval was granted to Gamida Cell Ltd. . Clinicians and pediatric experts cited in the FDA statement emphasized how the product can offer a valid therapeutic option for patients for whom a compatible donor cannot be found, complementing current strategies involving immunosuppression or transplantation from related donors or traditional cord blood.

The therapeutic procedure described involves reduced intensity conditioning followed by administration of the cellular product. According to the statement, the resulting shortening of time to neutrophil recovery can translate into shorter hospital stays and potentially lower infection incidence, although the studied population remains limited and open questions persist regarding long-term management of autoimmune cytopenias.

The approval represents a breakthrough in the treatment landscape for SAA, a rare and potentially fatal disease characterized by the bone marrow's inability to produce blood cells; however, it remains essential that expert centers continue to monitor clinical outcomes and complications over time to clearly define the net benefits and limitations of the product.

Product and Treatment Information Omisirge (omidubicel-onlv) was approved by the FDA on December 8, 2025, and is indicated for patients with severe aplastic anemia aged six years or older who require HSCT following reduced intensity conditioning and for whom a compatible donor is not available. The product is obtained from umbilical cord blood whose stem cells are treated with nicotinamide prior to administration to enhance their functional characteristics. In the cited study, among 14 evaluable patients, neutrophil engraftment was observed in 12 cases, with median time to neutrophil recovery of 11 days (range 7–20). The most frequently reported adverse effects are febrile neutropenia, viral and bacterial infections, hyperglycemia, immune thrombocytopenia, and pneumonia ; additionally, autoimmune cytopenias occurred in 25% of patients. The authorization received Orphan Drug and Priority Review designations; the authorization holder is Gamida Cell Ltd. . Use of the product should be evaluated considering therapeutic alternatives (immunosuppression, transplantation from related donors, use of unmodified cord blood) and the need for facilities capable of managing infectious and autoimmune complications post-transplant.

Glossary Severe Aplastic Anemia (SAA) : a rare condition in which the bone marrow fails to adequately produce red blood cells, white blood cells, and platelets, with elevated risk of infections and bleeding. Hematopoietic Stem Cell Transplantation (HSCT) : a procedure that replaces defective bone marrow with healthy hematopoietic stem cells to restore blood cell production. Umbilical Cord Blood (UCB) : a source of stem cells collected at birth from the umbilical cord; can be used as an alternative to adult donors but has limitations such as slower hematopoietic recovery. Nicotinamide : a form of vitamin B3 used here as a chemical agent to modify and enhance stem cells harvested from cord blood. [ppie]FDA — Press Release: FDA Approves First Cellular Therapy to Treat Patients with Severe Aplastic Anemia (December 8, 2025). https://www.fda.gov/news-events/press-announcements/fda-approves-first-cellular-therapy-treat-patients-severe-aplastic-anemia (accessed December 9, 2025).[/ppie]

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