Long Term Outcomes of Patients with Aggressive T-Cell Non-Hodgkin Lymphoma Undergoing Allogeneic Stem Cell Transplantation: Retrospective Results from a Single Center
Authors: Salhotra Amandeep , Nikolaenko Liana , Chen Lu , Tsai NI-Chun , Smith Diane Lynne , Nademanee Auayporn P. , Popplewell Leslie L. , Herrera Alex F. , Mei Matthew , Forman Stephen J. , Zain Jasmine M. 
Published: November 2019

Background: Mature T cell and NK cell neoplasms collectively known as peripheral T-cell lymphomas (PTCL) comprise 15-20% of Non-Hodgkin lymphomas in adults and have a poor prognosis with a 5-year survival of 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. There are few studies that 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 including transformed mycosis fungoides and NK/T-cell lymphoma without prior autologous transplant who underwent allo-HCT at City of Hope from January 2000 to June 2018 after IRB approval was obtained. Descriptive statistics were used to summarize baseline patient demographic, treatment, and disease characteristics. Kaplan-Meier curves and the log-rank test were used to evaluate the overall survival (OS) and progression-free survival (PFS). 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: 87 patients were included for the analysis. Median age at the time of allo-HCT was 49 years (range 2-70 years). Histologies were PTCL-NOS (n=21); transformed CTCL (n=19); NK T-cell lymphoma (n=17); AITL (n=15), ALCL (n=7); gamma delta T-cell lymphoma (n=6) and other rare subtypes (n=2). None of the patients had a prior auto transplant. 42 patients (48%) received myeloablative conditioning, with the majority of patients receiving FTBI based conditioning (n=39) and three patients received BEAM regimen for conditioning. 45 patients (52%) received reduced intensity conditioning; fludarabine/melphalan based-conditioning was the most common regimen used (n=39). Sibling HCT was performed in 47 patients (54%), while MUD HCT was performed in 36 patients (41%) with fully matched HLA unrelated donor in 15 (17%) and HLA mismatched in 21 (24%) patients; 4 (5%) received haploidentical HCT. GVHD prophylaxis consisted of tacrolimus/sirolimus (n=54), tacrolimus/sirolimus/MTX (n=11), tacrolimus or cyclosporine/MTX (n=7), tacrolimus or cyclosporine/MMF (n=7), post-transplant cyclophosphamide/tacrolimus/MMF (n=5) and other (n=3). Source of stem cells was PBSC in 77 (88%), bone marrow in 5 (6%), and cord blood in 5 (6%) patients. At the time of allo-HCT, there were a total of 25 (29%) patients in complete remission (CR1 n=15, CR2+ n=10), 25 (29%) patients 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). Relapses at 5 and 10 years were both 24% (95% CI: 16%-34%), while NRM at 5 and 10 years was 28% (95% CI: 19%-39%) and 37% (95% CI: 25%-50%), respectively. At day 100 after allo-HCT, the rates of acute GVHD grade II-IV were 41% (95% CI: 30%-51%) and grade III-IV of 16% (95%CI: 9%-25%). 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 (MSD vs MUD), stem cell source or remission status prior to allo-HCT did not predict for overall survival in our study.
Conclusions: Our results constitute the largest reported single-institution series with a long-term follow-up on allo-HCT outcomes in patients with aggressive T-cell NHL. The 5-year PFS and OS of 47 and 53%, respectively, are encouraging for the high-risk T-cell NHL patients with limited treatment options.

Disclosures
Salhotra: Celgene: Other: Research Support; Kadmon Corporation: Other: Non paid consultant. Popplewell:City of Hope: Employment. Herrera:Adaptive Biotechnologies: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; AstraZeneca: Research Funding; Merck: Consultancy, Research Funding; Genentech, Inc.: Consultancy, Research Funding; Pharmacyclics: Research Funding; Immune Design: Research Funding; Kite Pharma: Consultancy, Research Funding. Mei:Seattle Genetics, Inc.: Research Funding. Zain:spectrum: Honoraria; Seattle Genetics: Honoraria, Speakers Bureau.