A small study has demonstrated an improved process for making half-matched bone marrow or stem cell transplants for persons with blood cancer more successful.

Although the use of a genetically fully matched donor has yielded the best results in bone marrow transplant, many patients lack a fully matched related or unrelated donor. However, nearly every patient has a half-matched, or haploidentical relative. The successful use of haploindentical donors would greatly expand the number of donors available to every patient, yet half-matched bone marrow or stem cell transplants have been largely unsuccessful.

Neal Flomenberg, MD, chair of the department of medical oncology at Thomas Jefferson University Hospital in Philadelphia, Pennsylvania, and colleagues recently tested their new two-step approach to haploidentical hematopoietic stem cell transplantation. The 27 patients participating in the phase I/II trial had been diagnosed with leukemia, lymphoma, or myelodysplasia (median age: 52 years).

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First, after undergoing radiation therapy, the patients were given a specified dose of T cells from their half-matched family donor—the person’s parent, sibling, or child. This was followed by administration of the drug cyclophosphamide to enhance tolerance to the infused donor T cells.

In the second step of the transplant, patients were given a dose of the donor’s stem cells to help normalize the patient’s blood counts and further strengthen his or her new immune system.

As Flomenberg’s team reported in the journal Blood, 17 of the 27 patients were alive 6 months posttransplant. Based on a follow-up of 28 to 56 months, 3-year probability of overall survival for the whole cohort was 48%, increasing to 75% for those who had been in remission at the time of transplantation.

The researchers called these outcomes encouraging, particularly in good-risk patients, and suggested that this procedure be further explored.