Outpatient Haploidentical Stem Cell Transplantation Using Post-Transplant Cyclophosphamide Is Feasible. Experience in a Single Latin-American Center

Introduction: Only a minority of patients can find a fully matched donor for hematopoietic stem cell transplantation (HSCT). HLA-haploidentical HSCT is an attractive option since the likelihood of identifying a donor is high. Stimulated by economic constraints in developing countries and the significant expenses related to HSCT, in an effort to lower costs and resources, our center has performed an outpatient-based haplo-HSCT program since 2012. In the present study, we describe the characteristics of those patients and analyze the factors relating to the performance of a successful ambulatory procedure.

Methods: Adult patients who underwent haplo-HSCT in an outpatient-intended basis were eligible. All were required to have a Karnofsky score ³70%, serum creatinine <2 mg/dL, residence near the hospital, an adequate caregiver, with appropriate educational level and treatment adherence. The conditioning regimen was delivered in all individuals as outpatients and consisted of fludarabine 25 mg/m²/day (day -5 to -3), cyclophosphamide (Cy) 350 mg/m²/day (day -5 to -3), and oral busulfan 4 mg/kg/day (day-2 to -1) or melphalan 50-100 mg/m² (day -2 to -1). GVHD prophylaxis consisted of Cy (50 mg/kg/day, days 3 and 4), cyclosporine 6 mg/kg, and mycophenolate mofetil 1 g/day. After infusion, patients stayed at home and were seen in the outpatient clinic every day for the first 72 hours, every other day until hospitalization requirement or engraftment; afterwards weekly and bi-weekly through day +100, and thereafter according to physician criteria. Patients were instructed to report the presence of fever among other adverse effects at any hour of the day. Hospital beds were available for those needing admission.

Results: Thirty-six consecutive patients from February 2013 to May 2017 were eligible for analysis. Median follow-up was 12 months (4-40). Median age was 23 years (range, 15-63); 13 were female. Acute leukemia (13 lymphoblastic and 5 myeloblastic) was the most common indication for HSCT, followed by Hodgkin's lymphoma (5), non-Hodgkin's lymphoma (4), chronic myeloid leukemia (3), aplastic anemia (3), chronic lymphocytic leukemia (2), and chronic myelomonocytic leukemia (1). Median PBSC CD34⁺ cells/kg was 7x10⁶ (range, 2-16). Neutrophil engraftment was achieved at a median of 16 days (range, 11-23), with platelet recovery at a median of 16 days (range, 13-100). Seven patients (19%) were followed in a fully outpatient basis while the other 29 (81%) required hospitalization. The median length of stay (LOS) was 10 days (0-35). Seven patients (19%) stayed ≤7 days in hospital, while 22 patients >7 days. Febrile neutropenia was the most common reason for hospitalization (65.5%). Other reasons included mucositis (27.5%) and hemorrhagic cystitis (6.9%). The median day of admission was day +3 (1-14). The development of febrile neutropenia (P=0.004) and a slower neutrophil engraftment (P=0.023) were significantly associated with the need for hospital admission. Eight of the 18 patients admitted for febrile neutropenia had a rapid response and no source of infection evidenced, thus LOS was ≤10 days in 9 patients. Age, gender, mucositis, and acute graft versus host disease were not associated with hospitalization need. The 2-year overall survival (OS) was 50% for patients with a completely ambulatory transplant vs. 28% for those requiring hospitalization (log rank P=0.08).

Conclusion: Currently conventional transplantation is unaffordable for the majority of patients living in the developing world. Almost 20% of our patients did not require hospital admission. Although 62% of the patients were admitted, most of them had a short LOS. Our outpatient haploidentical HSCT program is feasible, potentially resulting in cost savings and perhaps a higher quality of life.

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