Long Term Outcomes of Patients with Aggressive T-Cell Non-Hodgkin Lymphoma Undergoing Allogeneic Stem Cell Transplantation: Retrospective Results from Single Center

Introduction Peripheral T-cell lymphomas (PTCL) comprise 15-20% of adult non-Hodgkin lymphoma and have a poor prognosis; 5-year survival is less than 30% for the most aggressive subtypes. Allogeneic HCT (allo-HCT) is offered to eligible patients as a potentially curative modality in the salvage setting or in high risk patients to consolidate an initial response to frontline therapy. Objective To report clinical outcomes derived from large sample size and long-term follow up data. Methods We retrospectively reviewed medical records of 87 consecutive patients with PTCL who underwent allo-HCT at City of Hope from January 2000 to June 2018. Baseline patient demographic, treatment, and disease characteristics were summarized by descriptive statistics. Overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan-Meier curves and the log-rank test. Cumulative incidences of time to relapse and time to non-relapse mortality (NRM) were calculated with relapse and NRM as competing risks. Cumulative incidences of acute and chronic GVHD were calculated as time to onset of GVHD with relapse and death as competing events for GVHD. Results Median age at allo-HCT was 49 (range 2-70) years. Histologies were PTCL-NOS (n=21); transformed CTCL (n=19); NK TCL (n=17); AITL (n=15), ALCL (n=7); γδTCL (n=6) and other rare subtypes (n=2). No patients had a prior auto transplant. 42 patients (48%) had myeloablative conditioning; FTBI-based (n=39), or BEAM regimen (n=3). 45 patients (52%) had reduced intensity conditioning with a fludarabine/melphalan based regimen in 39. Sibling HCT was done in 47 (54%) patients. MUD HCT was done in 36 (41%); donors were fully HLA matched for 15 (17%) patients and mismatched in 21 (24%); 4 (5%) got haploidentical HCT. The most common GVHD prophylaxis was tacrolimus/sirolimus (n=54). Stem cell source was PBSC in 77 (88%), bone marrow in 5 (6%), and cord blood in 5 (6%) patients. At allo-HCT 25 (29%) patients were in complete remission, 25 (29%) in partial remission, 22 (25%) with induction failure and 14 (16%) with relapsed disease. The median follow-up among survivors was 6.9 years (range 1.1-15.5). The 5- and 10-year PFS was 47% (95% CI: 36%-58%) and 38% (95% CI: 26%-50%), respectively. The 5- and 10-year OS was 53% (95% CI: 41%-63%) and 42% (95% CI: 29%-54%), respectively (Fig.1). At day 100 after allo-HCT, the rate of acute GVHD grade II-IV was 41% (95% CI: 30%-51). Chronic GVHD rates at 3 years were 62% (95% CI: 51%-72%), with extensive GVHD of 55% (95% CI: 44%-65%). On univariate analysis, age (> 60 or not), sex, TBI-based conditioning, donor type, stem cell source or remission status prior to allo-HCT did not predict for OS. Conclusions This large single-institution series with a long-term follow-up on allo-HCT outcomes in patients with high-risk, aggressive T-cell NHL shows encouraging survival outcomes for these patients with limited treatment options.