Probability of Finding a Matched Unrelated Donor for An Asian Indian Patient Who Needs a Stem Cell Transplant.

Abstract 4343

In March 2008 we initiated a matched unrelated donor (MUD) bone marrow transplant program. Forty three searches have been performed through the National Marrow Donor Program USA (NMDP) and through the German Registry (DKMS) and completed data is available on 17 patients. High resolution HLA typing for A, B, DRB1, C and DQB1 alleles was done by Histogenetics (USA), NMDP or DKMS. Of the 17 patients for whom the search process was completed we identified a 10/10 matched donor for 7 patients, a 9/10 for 7 patients and an 8/10 for one patient. The 8/10 mismatch was at the C and DQB1 loci. Thus 15 of 17 (88%) had a suitable donor identified. After the preliminary search 2 patients were unlikely to have a donor. Of the15 matched donors, 4 were Caucasian and 11 were Asian. HLA is determined by the racial background of the individual and therefore the probability of finding a high resolution allele matched donor for an Asian Indian would have been low in registries that are predominantly Caucasian. Identification of matches from among the primarily Caucasian donor pool is interesting and may reflect a Caucasoid background in some of the population in the sub continent. In 11 out of the 17 completed searches an Asian donor was identified (61%). The NMDP has 7.5 million donors of which 553,000 are Asian and Pacific Islanders, 141,462 are South Asian, and 36,790 are Southeast Asian. These data exclude Asian donors reported as being from multiple races. Thus there was a 61% probability of finding a matched donor from among the 141,462 South Asian donors registered with the NMDP.

Eleven patients have had a MUD transplant (Acute Myeloid Leukemia: 8, Acute Lymphatic Leukemia: 2 and Myelofibrosis: 1): 3 patients died before engraftment, 8 engrafted, 5 remain in remission, 2 have relapsed and one died of sepsis 100 days post transplant. The remaining four patients with matched donors are awaiting transplant.

Since identification of a well-matched donor (allele matched at HLA-A, B, C, DRB1) is important for good outcome after MUD transplantation, these early search data for Indian patients suggest the need for a greater number of donors in India to be available and HLA typed in order to increase the probability of finding a suitable match for patients needing a MUD transplant.