ASH: FDA okays Gamida aplastic anaemia therapy as data drops

The first cell therapy for severe aplastic anaemia – Gamida Cell's Omisirge – has been approved by the FDA, as positive results from a pivotal trial were presented at the ASH congress.

Omisirge (omidubicel) is an off-the-shelf cell therapy that has been approved since 2023 as a therapy to reduce the risk of infection in patients with blood cancers who receive a haematopoietic stem cell transplant (HSCT).

The extension of its label to include severe aplastic anaemia comes on the back of an open-label, single-arm study in 19 patients aged six and over with severe aplastic anaemia, a rare, life-threatening haematologic disorder in which the bone marrow fails to produce sufficient blood cells. Untreated SAA can result in 80% to 90% mortality in one to two years.

Treatment for SAA depends on age and usually consists of either immunosuppressive therapy and/or hematopoietic stem cell transplant, preferably from a matched sibling or otherwise related donor. If a donor is not available, an umbilical cord transplant from an unrelated donor can be tried, although these tend to have delayed recovery of the bone marrow as well as an increased risk of infections while the patient is immunosuppressed.

Omisirge is a ready-prepared therapy based on cord blood stem cells that have been chemically enhanced with nicotinamide, a form of vitamin B3, which increases the quantity and the functionality of the cells.

The approval means that for patients without a family donor, formally with almost no treatment options, Omisirge offers the possibility of a cure with high survival rates and manageable toxicity. It also cuts the treatment time from a regular cord blood procedure from around 25 days to eight days.

In the study reported at ASH, 95% of patients treated with Omisirge achieved a rapid recovery in infection-fighting neutrophil cells, with a median time to recovery of eight days. The patients, with a median age of 20, had not responded to conventional treatments for aplastic anaemia. Overall survival and disease-free survival came in at 94%.

There were no cases of severe or chronic graft-versus-host disease (GvHD), where the donated cells mount an immune response against the transplant recipient, although three patients had mild GvHD. Autoimmune cytopenias occurred in around a quarter of the patients.

The approval of Omisirge for severe aplastic anaemia in patients aged six and over with no matched HSCT donor is "revolutionary in the therapeutic landscape and fundamentally changes how we approach treatment," said Vinay Prasad, director of the FDA's Center for Biologics Evaluation and Research (CBER), who added that earlier treatment "has potential to alter one's life course."