Improved Outcomes of Haploidentical Blood and Marrow Transplantation in Hematologic Malignancies: A Single Center Study of 514 Cases

Introduction: With GIAC regimen, haploidentical blood and marrow transplantation (haplo-BMT) has achieved comparable outcomes with identical sibling transplant (Dao-Pei Lu et al., Blood 2006; 107:3065). Our previous study has shown that the third party cell co-infusion in haplo-BMT (GIAC-3 regimen) could significantly reduce aGVHD and transplant-related mortality (TRM). We have also demonstrated that individualized chemotherapy to decrease leukemia burden followed by conditioning could improve disease-free survival (DFS) in refractory/relapsed AML.

Objective: To learn the outcomes of our haplo-BMT with these integrated approaches, all patients who received haplo-BMT for hematologic malignancies in our center were analyzed retrospectively.

Methods: Between April 2012 and December 2014, consecutive 514 patients with hematologic malignancies who underwent haplo-BMT were included. The median age was 20 (1.8 to 64) years old. The diagnosis included AML 232 (45.1%), ALL 207 (40.3%), MDS 27(5.3%), CML 14 (2.7%), lymphoma 13 (2.5%) and others 21 (4.1%). Transplants at CR1, ≥CR2 or advanced disease were 216 (42.0%), 114 (22.2%), 184 (35.8%), respectively. All patients received unmanipulated bone marrow (BM) and peripheral blood stem cells as graft after myeloablative conditioning plus ATG. Majority of the patients with AML received BuCy-based conditioning, while most ALL patients received TBICy-based regimen. Fludarabine was substituted for cyclophosphamide in some patients due to impaired organ function or high tumor burden. For refractory/relapsed diseases, individualized chemotherapy followed by conditioning was administered. Cyclosporine/tacrolimus, short-term Methotrexate, and Mycophenolate mofetil were employed for GVHD prophylaxis. Either 1ml/kg (recipient's body weight) haploidentical BM from the second haploidentical donor or one unit of unrelated cord blood was infused right after haplo-BMT as the third party cells. Minimal residual disease (MRD) was monitored routinely by quantitative PCR or flow cytometry. The patients with persistent MRD were interfered by immunosuppressant withdrew, adoptive immunotherapy with cytokine induced killer or NK cells or donor lymphocyte infusion.

Results: All patients but 5 achieved durable engraftment. The cumulative incidences of grade II to IV aGVHD and grade III to IV aGVHD were 32.2%, 19.8%, respectively. The cumulative incidences of cGVHD and extensive cGVHD were 48.3%, 18.4%, respectively. 100-day TRM and 2-year TRM were 4.1%, 14.9%, respectively. Two-year relapse rate was 22.8%. With the median follow up 17 (6 to 38) months, overall 2-year DFS rates in CR1, ≥CR2 and advanced disease were 75.6%, 70.9%, 49.2%, respectively. For AML, two-year DFS rates in CR1, ≥CR2 and advanced disease were 74.1%, 76.9%, 48.2% (CR1 vs. ≥CR2, p=0.84; CR vs. advanced disease, p=0.000). For ALL, two-year DFS rates in CR1, ≥CR2 and advanced disease were 78.9%, 56.6%, 38%, respectively (CR1 vs. ≥CR2, p=0.018; CR1 vs. NR, p=0.000; ≥CR2 vs. NR P=0.02 ).

Conclusions: With our strategies, overall outcomes of haplo-BMT have been improved remarkably and very encouraging. Therefore, haplo-BMT should be an important way to save life for the patients with hematologic malignancies who need urgent BMT but without matched either sibling or unrelated donor.