HIGH SURVIVAL RATES IN ELDERLY PATIENTS UNDERGOING ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION IN SÃO PAULO, BRAZIL

Abstract

Objectives: Many hematological diseases, such as Acute Myeloid Leukemia (AML) and Myelodysplastic Syndromes (MDS) commonly affect individuals diagnosed in their seventh decade of life or later. Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) can cure these conditions. However, elderly patients are often considered ineligible due to high morbimortality rates. Recent advances in supportive care and new conditioning regimens have made HSCT more feasible and safer for elderly patients. However, there are few reports regarding HSCT in patients aged 70-years or older in Brazil. Material and methods: This retrospective observational study analyzed 44 patients aged 65-years or older who underwent their first allogeneic HSCT for myeloproliferative neoplasms: acute myelogenous leukemia (AML, n = 27), myelodysplastic syndrome (MDS, n = 12), or myelofibrosis (MF, n = 5), at two Brazilian centers in São Paulo between December 2013 and March 2024. Clinical data were collected using standardized forms based on information from electronic medical records. Results: The median age was 70-years (range: 65‒81), with most patients being male (64%). The majority of donors were haploidentical (59%), followed by matched unrelated donors (30%) and matched sibling donors (11%). All patients received Reduced-Intensity Conditioning (RIC) regimens, with the vast majority receiving mobilized peripheral blood as the stem cell source (n = 40, 91%), and only four (9%) bone marrow. Among the 27 patients with AML, seven (26%) were not in complete remission before transplant. The main Graft-Versus-Host Disease (GVHD) prophylaxis was the combination of mycophenolate mofetil and cyclosporine or sirolimus. T-cell depletion was used in most cases with either post-transplant cyclophosphamide in 26 patients (59%) or Antithymocyte Globulin (ATG) in 15 patients (34%). Median follow-up was 18-months (range: 4‒138). The Cumulative Incidence (CI) of acute GVHD grade II‒IV was 28% but only 9% for grade III‒IV. The CI of chronic GVHD at 2-years was 39%, but only 4 patients (9%) required prolonged immunosuppression. Median Progression-Free Survival (PFS) and Overall Survival (OS) were not reached within two years of follow-up. PFS and OS at two years were 54% and 64%, respectively. The CI of Non-Relapse Mortality (NRM) was 11% at 100 days and 19% at two years. The main causes of death were infections (33%), followed by relapse or progression (29%). Discussion: This retrospective study demonstrates that allogeneic HSCT is an effective and safe curative option for myeloproliferative neoplasms in patients aged 65-years or older. Despite the use of RIC regimens and the inclusion of patients not in remission before transplantation, we observed a low relapse rate. Additionally, the rates of NRM and chronic extensive GVHD were relatively low. Conclusions: Although the study has limitations, including its retrospective nature and lack of comparison with other specific therapies, the findings suggest HSCT is a viable treatment option for elderly patients.