Making More From Umbilical Cord Blood
Umbilical cord blood has been used as a source of blood-forming stem cells for decades. These cells can rebuild the blood and immune system after intensive treatment, making cord blood an important transplant option for people with serious blood disorders and cancers.
One challenge, however, is that a single cord blood unit contains a limited number of stem and progenitor cells. That can mean a longer wait before the transplanted cells begin producing enough healthy blood cells.
A Phase III clinical trial explored whether researchers could improve that process by expanding some of the cord blood cells in the laboratory before transplantation. The resulting treatment, called omidubicel, was then compared with a standard cord blood transplant.
How the Study Worked
The trial included 125 patients between 13 and 65 years old with blood cancers such as leukemia. Participants were randomly assigned to receive either omidubicel or a standard umbilical cord blood transplant.
Omidubicel starts with a single donated cord blood unit. Researchers expand a portion of its blood-forming stem and progenitor cells in the laboratory while keeping another portion unexpanded, creating a transplant designed to provide more cells that are ready to begin rebuilding the blood system.
Researchers looked closely at several important parts of recovery, including:
- How quickly white blood cells recovered
- Platelet recovery
- Infection rates
- Time spent in the hospital
- Graft-versus-host disease and survival
Blood Cell Recovery Happened Faster
The clearest difference was how quickly patients regained neutrophils, a type of white blood cell that helps protect the body against infection. Patients receiving omidubicel reached neutrophil recovery in a median of 12 days, compared with 22 days for those receiving a standard cord blood transplant.
The study also found faster platelet recovery. By day 42, 55% of omidubicel patients had reached platelet recovery, compared with 35% of patients receiving standard cord blood. Those extra days matter after a transplant. Until blood cells recover, patients are especially vulnerable to infection, bleeding, and other complications.
Fewer Infections During Early Recovery
The faster recovery was accompanied by another encouraging finding: fewer serious infections. During the first 100 days, 37% of patients assigned to omidubicel experienced a moderate-to-severe bacterial or invasive fungal infection, compared with 57% in the standard transplant group.
Serious viral infections during the first year were also less common, occurring in 10% of the omidubicel group compared with 26% of the standard cord blood group. This suggests that helping the blood and immune system recover more quickly may also help patients move through one of the most vulnerable parts of the transplant process.
More Time Outside the Hospital
The difference was noticeable beyond laboratory tests. During the first 100 days after transplantation, patients assigned to omidubicel spent a median of 61 days alive and outside the hospital, compared with 48 days for those receiving a standard cord blood transplant.
Patients receiving omidubicel were also discharged sooner after transplant, with a median hospital stay of 27 days compared with 35 days in the standard treatment group. For patients going through an intensive stem cell transplant, getting home sooner can be a meaningful part of recovery.
What About Safety and Survival?
Researchers also looked at serious complications such as graft-versus-host disease (GVHD), which occurs when transplanted immune cells attack the recipient’s tissues.
Rates of GVHD were not significantly different between the two groups. Serious adverse events considered possibly related to the stem cell products were also similar, 40% with omidubicel and 41% with standard cord blood.
The trial did not find a statistically significant difference in overall survival between the groups during the available follow-up. This means the strongest benefits seen in the study involved faster blood-cell recovery, fewer early infections, and less time in the hospital, rather than a proven survival advantage.
Expanding the Potential of Cord Blood
This study highlights an interesting idea in regenerative medicine: sometimes progress does not require finding an entirely new source of stem cells. Instead, researchers may be able to improve how existing cells are prepared before they are used.
By expanding blood-forming cells from umbilical cord blood before transplantation, omidubicel shortened the time needed for important blood cells to recover. Patients also experienced fewer infections and spent more time outside the hospital during the early recovery period.
For regenerative medicine, the trial provides a strong example of how laboratory cell processing can potentially make established stem cell treatments more efficient and help patients through one of the most challenging stages of transplantation.
Source
Horwitz ME, Stiff PJ, Cutler C, et al. Omidubicel vs standard myeloablative umbilical cord blood transplantation: results of a phase 3 randomized study. Blood. 2021;138(16):1429–1440. doi: 10.1182/blood.2021011719. Available from: https://ashpublications.org/blood/article/138/16/1429/476235/
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