11 Haploidentical Hematopoietic Stem Cell Transplantation (Haplo-SCT) with Pre-Transplant Immunosuppression and Post-Transplant Cyclophosphamide (Post-Cy) in Severe Thalassemia: A Novel Approach Transplant for Nonmalignant Diseases

Track: BMT Tandem "Scientific" Meeting
Wednesday, February 11, 2015, 4:45 PM-6:45 PM
Seaport Ballroom ABC (Manchester Grand Hyatt)
Suradej Hongeng, MD , Faculty of Medicine Ramathibodi hospital, Mahidol University, Bangkok, Thailand
Samart Pakakasama, MD , Faculty of Medicine Ramathibodi hospital, Mahidol University, Bangkok, Thailand
Usanarat Anurathapan, MD , Faculty of Medicine Ramathibodi hospital, Mahidol University, Bangkok, Thailand
Borje S. Andersson, MD, PhD , Stem Cell Transplantation and Cellular Therapy, UT M.D. Anderson Cancer Center, Houston, TX
Presentation recording not available for download or distribution as requested by the presenting author.
Background

Currently, the thalassemia free survival rate after hematopoietic stem cell transplant (HSCT) is about 80-90% with either matched sibling or unrelated donor. However, the probability to find a suitable door is only 25-50%. Since most of these patients (pts) could not find the potential donor, we would like to investigate the haplo-SCT in thalassemia.

Patients and Methods

Between Jan 2013 and October 2014, 15 thalassemia patients (pts) underwent haplo-SCT. Eight subjects were male and 7 were female. The median age was 16 yrs (range; 2-22). Eleven of 15 received stem cells from mother and 4 from father. Twelve of 15 were high risk class 3. These high risk class 3 also received hydroxyurea  20 mg/kg/d for at least 3 months prior to HSCT. All pts received 2 courses of pre-transplant immunosuppression (PTIS) consisting of fludarabine (Flu) 40 mg/m2/d together with dexamethasone (dex) 25 mg/m2/d for 5 days. After 2 courses of PTIS, all pts received a reduced-toxicity conditioning regimen consisting of thymoglobulin 1.5 mg/kg/d (d-11 to d-9), Flu 35 mg/m2/d i.v. (-7 to -2) each dose immediately followed by busulfan (Bu) 130  mg/m2once daily i.v. (d-7 to d -4) for pts  > 10 years and 0.95-1.2 mg/kg every 6 hr (d-7 tod-4) for pts < 10 yrs. GVHD prophylaxis consisted of cyclophosphamide (Cy) 50 mg/kg/d (d +3 to d+4). Tacrolimus was given for 6 months to 1 yr started together with mycophenolate mofetil on d+5, the latter was quickly tapered after 2 months. T-cell repleted peripheral blood stem cells were given to all pts targeting a CD34+ dose of 7-10 x 106 cells/kg.

Results

Fourteen of 15 were engrafted with full donor chimerism (100%) while one pt suffered graft failure. However, this pt received second transplant on day +30 with minimal conditioning regimen and additional PBSC, after which she achieved full donor chimerism. The median time to neutrophil engraftment was 18 days (range; 14 -22). Six pts had acute GVHD gr I, 3 grade II and1 gr III. Only one had limited chronic GVHD. At this time, all 15 pts survive thalassemia-free and have sustained full donor chimerism (100%). The thalassemia free survival and overall survival rates are 100%. The median follow up time was 12 months (range 4-22).

Conclusion       

Haplo-SCT for high risk thalassemia pts with our novel approach is safe, and should be considered as a modality to secure thalassemia-free survival with a low risk of graft rejection and treatment-related mortality. With this result, our Haplo-SCT in thalassemia pts has favorable outcome as related and unrelated HSCT (Thalassemia free survival rate > 90%). In view of our results, we suggest that all thalassemia pts even those with high risk class 3 features should be offered the chance for cure with HSCT.

Disclosures:
B. S. Andersson, Otsuka, Consult: Consultancy