Allogeneic Stem Cell Transplantation in a Large Urban Cohort of North-American Adult T-Cell Leukemia/Lymphoma

Introduction: Adult T-cell leukemia lymphoma (ATLL) is a rare hematologic malignancy caused by human T-cell lymphotropic virus (HTLV-1) with dismal cure rates and poor response to conventional chemotherapy. Allogeneic Hematopoietic Stem Cell Transplantation (AlloSCT) is the only therapeutic option which may offer the chance of long-term remission and cures in a subset of patients. We sought to investigate the outcomes of transplantation in one of the largest cohorts in North America.

Methods: A retrospective chart review study was conducted using the North-American ATLL and the Hematopoietic Precursor Cell transplantation databases at Montefiore Medical Center from 2011 to 2020. Variables collected include age, sex, ethnicity, ATLL subtype, molecular profile, previous treatments, conditioning regimens, type of transplant, immunosuppressive regimen, progression free survival (PFS) post-transplant and overall survival (OS) post-transplant.

Results: Fourteen patients with ATLL who received an AlloSCT from 2011-2020 were identified. Fifty-seven percent (8/14) of patients were male. Seventy-one percent (10/14) of patients were African American and twenty-nine percent (4/14) were Hispanic. Median age was 51 years. Sixty-four percent (9/14) of patients had Stage IV disease at the time of diagnosis. Forty-three percent (6/14) patients had acute and fifty-seven percent (8/14) had lymphomatous ATLL. Almost all patients (92%) were treated initially with EPOCH combination chemotherapy. Twenty-eight percent (4/14) of patients received interferon/zidovudine as bridge-to-transplant. Fifty-seven percent (8/14) of patients achieved complete remission (CR) prior to AlloSCT, 7% (1/14) were in partial remission, and 28% (4/14) were relapsed or refractory. Forty-three percent (6/14) of patients received SCT from a matched-related donor (MRD), 36% (5/14) from a haplo-identical donor and 21% (3/14) from a matched-unrelated donor (MUD). Ninety-three percent (13/14) of patients received a reduced-intensity conditioning (RIC) regimen pre-transplantation. Seven percent (1/14) received a myeloablative conditioning (MAC) regimen. RIC regimens consisted of fludarabine with melphalan +/- anti-thymocyte globulin (ATG) or fludarabine with cyclophosphamide with total-body irradiation in doses less than 500 cGy. Patients receiving haplo-identical SCT also received post-transplant cyclophosphamide (PTCy) for prevention of graft vs host disease (GVHD). The MAC regimen used included busulfan with cyclophosphamide at myeloablative doses. Twenty-eight percent (4/14) of patients relapsed post-alloSCT with a median relapse-free survival of 6 months (range 4-18 months). The median OS of the whole cohort was 27 months (8-82 months). Graft-versus-host disease (GVHD) developed in 28% (4/14) percent of patients. The most common manifestation was skin GVHD. Fifty-percent (7/14) of the patients are surviving to-date. Transplant-related mortality (TRM) at day 100 was 21% (3/14) of patients. Causes of death were complex and included several diagnoses in certain patients. The most frequent diagnoses associated with death were infection (28%), graft failure (14%), GVHD (14%), veno-occlusive disease of the liver (VOD) (7%), disease progression (14%) and unknown due to patient lost to follow-up (14%). The main infectious events included fungal (2), bacterial (1), and COVID-19 (1) infection. Forty-three percent (6/14) of patients remain in complete remission to date.

Conclusions: Allogeneic Stem Cell Transplantation offers long-term survival with a TRM of 21% in a disease with an inherently dismal prognosis. AlloSCT using several graft sources, is thus, a safe and well tolerated treatment modality and offers long term remissions.