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For patients with hematologic cancers, allogeneic hematopoietic stem-cell transplant with the advanced cell therapy omidubicel was associated with lower rates of non-relapse mortality and infection compared to myeloablative umbilical cord blood transplantation (UCBT), according to updated results of a phase III trial.

At 1-year post-transplant, the cumulative incidence of non-relapse mortality was numerically lower in the group randomized to omidubicel compared to the group assigned to standard UCBT (15% vs 29%, P=0.068), reported Mitchell Horwitz, MD, of the Duke Cancer Institute in Durham, North Carolina.

In addition, the study continued to show significant reductions in grade 2/3 bacterial or fungal infections in the omidubicel arm (45% vs 70%) and in grade 3 viral infections (8% vs 27%), he said at the Transplantation & Cellular Therapy Meetings (TCTM).

An , reported last year at the American Society of Hematology annual meeting, demonstrated faster hematopoietic recovery time with omidubicel (the study's primary endpoint), with a median time to neutrophil engraftment of 10 days compared to 20.5 days with UCBT (P<0.001). The analysis also showed reduced platelet engraftment time with the cellular product (37 vs 50 days, P<0.023).

The study's results have "certainly invigorated my enthusiasm for cord blood transplantation, which admittedly was high before the study," said Horwitz during his presentation at TCTM. "I feel this is a viable graft source."

"It needs to be compared to other graft sources -- obviously the haploidentical graft," he added. "This is a myeloablative transplant regimen, so we have no data comparing myeloablative cord blood to myeloablative haplo, and with this rapid and tremendous recovery, this has to be considered an option."

In the updated analysis, no significant differences were seen in disease-free survival (DFS) or relapse rates at 1 year:

• DFS: 63% with omidubicel vs 56% for UCBT
• Relapse: 23% vs 16%

A trend toward improved overall survival (OS) was observed with omidubicel (73% vs 60%), but with a study population of 125 patients, the trial was not powered for OS, Horwitz cautioned.

He also reported that patients who received omidubicel spent a median 60.5 days alive and out of the hospital in the first 100 days post-transplant, as compared with 48 days for those in the UCBT arm. This difference, as well as the reduced risk of infections, was "likely a function of the rapid engraftment of neutrophils that omidubicel recipients experience," Horowitz said.

Investigators saw no difference in incidence of chronic graft-versus-host disease (GVHD) between the two arms, at 34% with omidubicel versus 29% with UCBT for all-grade GVHD, and 23% in both arms for moderate or severe GVHD.

At the 1-year follow-up, there were no unexpected severe adverse events, Horwitz reported. There was one case of secondary graft failure at 6 months in an omidubicel recipient, which occurred concurrently with evidence of recurrent acute lymphoblastic leukemia. Post-transplant lymphoproliferative disorder was observed in two patients assigned omidubicel, and one patient in the UCBT arm developed donor-derived myeloid leukemia at 35 months post-transplant.

Of the 125 patients in the study, 108 comprised the as-treated population (52 transplanted with omidubicel and 56 with standard UCBT).

More than half of the study participants were male (57.5%), and the median age was 41 years. A majority of patients (58%) were white, 16% were Black, and 13.5% were Asian. Almost half (48%) had acute myeloid leukemia, 32.5% had acute lymphocytic leukemia, 7.5% had myelodysplastic syndromes, 5% had chronic myeloid leukemia, 4% had lymphoma, and 3% had a rare leukemia.

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