Corey Diamond, PharmD
In April 2023, FDA approved Omisirge (omidubicel-onlv–Gamida Cell Ltd.), a cell therapy derived from modified donor umbilical cord blood. Omisirge is the first FDA approval for an “expanded” umbilical cord blood product (i.e., umbilical cord blood products that have been cultured in a laboratory to artificially enhance natant stem cell production).
The market niche for Omisirge is to give stem cell transplant candidates—often patients suffering from blood cancers—an alternative option if they are unable to find a suitable donor.
Omisirge versus standard of care
The FDA approval of Omisirge is based on results of a Phase 3, randomized, multicenter study conducted by the manufacturer, Gamida Cell, Ltd. Results were published in the journal Blood in October of 2021. Researchers compared Omisirge transplantation to standard transplantation of umbilical cord blood. The trial consisted of 125 patients with confirmed blood cancers, including hematological malignancies, acute lymphoblastic leukemia, acute myelogenous leukemia, chronic myelogenous leukemia, myelodysplastic syndrome, lymphoma, and acute leukemia.
The primary outcome was the median time to engraftment, defined as an absolute neutrophil count of >500/μL. The research team found that patients treated with Omisirge had a statistically significant reduction in the time to engraftment versus patients treated with a standard umbilical cord blood transplant. In fact, patients in the Omisirge treatment arm had their median time to engraftment reduced by roughly half compared to the active comparator (10 days vs. 20.5 days, respectively).
Furthermore, the trial results were significant in three secondary outcomes, with Omisirge reducing the median time to platelet engraftment by 13 days as well as rates of infection and hospitalization. While the trial was not powered to detect differences in long term outcomes, the two treatment arms did not differ significantly in overall incidence of chronic graft versus host disease (GvHD), severity of GvHD, relapse rate within 15 months, nonrelapse mortality, cumulative neutrophil engraftment by day 42, and overall survival.
Advantages
Omisirge’s theoretical advantage as an “expanded” blood-cell therapy product allows it to combine the ideal properties of both bone marrow and umbilical cord blood as a graft source. Like a bone marrow sourced graft—with an average engraft time of 10 days—Omisirge engrafts extremely quickly, reducing the risk of infection. However, unlike a bone marrow graft source, and similar to an umbilical cord graft, Omisirge may yield long term advantages, such as better survival and GvHD rates.
With the approval of Omisirge, oncology experts now have more treatment avenues available for patients who are unable to secure a fully matched bone marrow donor. Along with that, clinical algorithms for selecting a graft source may need to be re-evaluated.
“Today’s approval is an important advance in cell therapy treatment in patients with blood cancers,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, in a news release. “Hastening the return of the body’s white blood cells can reduce the possibility of serious or overwhelming infection associated with stem cell transplantation. This approval reflects FDA’s continued commitment to supporting development of innovative therapies for life-threatening cancers.”
Safety and warnings
Omisirge carries similar risks to other approved umbilical cord products, such as a boxed warning for infusion reactions, GvHD, engraftment syndrome, and graft failure.
Additionally, patients may require monitoring for signs and symptoms of possible transmission of serious infections, as well as life-long monitoring for secondary malignancies or rare genetic diseases transmitted from donor cells. ■