Haploidentical HCT with Cyclophosphamide for High-Risk Leukemias

Myeloablative transplants using T-cell-replete haploidentical grafts and post-transplant cyclophosphamide can result in a 2-year overall survival (OS) of 57%, with cumulative incidence of relapse reaching 44% at 3 years according to results of a phase II study presented at the BMT Tandem Meetings.

The study enrolled 97 patients with leukemias in complete remission or chemosensitive lymphomas with at least a partial remission transplanted at Johns Hopkins University. Median age of patients was 42 years (range, 1-65), and median number of HLA allele mismatches from haploidentical donors was 4/10.

Post-transplant immunosuppression was cyclophosphamide at 50 mg/kg/day on days 3 and 4, followed by mycophenolate mofetil for 30 days and tacrolimus for 6 months. Lead author Dr. Heather Symons noted that the selective depletion of proliferating alloreactive T cells brought about via post-transplant cyclophosphamide makes the agent very effective at controlling GVHD.

The cumulative incidence of relapse at three years was 44% with minimal residual disease (MRD) status associated with the incidence. At a median follow up of 18 months, 1-year OS was 72%.

In an oral presentation of the research, Dr. Symons concluded that haploidentical transplantation with post-transplant cyclophosphamide resulted in very low rates of acute and chronic GVHD, low transplant-related mortality at 100 days, and that haploidentical HCT warrants further study.

Symons H, et al. Biol Blood Marrow Transplant