Long-term outcome of a Phase II study of BM transplants, partially depleted ex-vivo of CD5-positive and CD8-positive T-lymphocytes in unrelated and related donor 1 antigen mismatched recipients

Background: Mismatched family donor and unrelated donor BM transplants are associated with a high risk of acute GvHD. While T-cell depletion is the best method to reduce risk of acute GvHD, there was a reluctance to use T-cell depletion in the mismatched setting because of increased risk of rejection and relapse. Partial T-cell depletion, by the panning of CDS and CD8 positive T cells may reduce complications related to GvHD -without compromising outcomes. Method: In a long-term follow-up of a Phase II study of partial T-cell depletion by panning for BM transplant, 32 recipients received transplants from a single-Ag (HLA A, B, or DR) mismatched family donor; or an HLA serologically-matched unrelated donor. Patients were studied for engraftment, GHD, relapse and survival. Results: 30 (94%) of the patients marrow engrafted. The cumulative risk of Grade 2-4 acute GvHD was 62 ± 9%; of Grade 3-4 GvHD, 11 ± 6%. The 4-year cumulative risk of relapse was 18 ± 8% and actuarial survival was 44 ± 9%. Discussion :Partial T-cell depletion had a low rate of severe acute GvHD without compromising engrafment or relapse risk.