Allogeneic Hematopoietic Stem Cell Transplantation for T-Prolymphocytic leukemia: A Retrospective Analysis From the Societe française De Greffe De Moelle Et De Therapie Cellulaire
Authors: Guillaume Thierry , Beguin Yves , Leblond Véronique , Blaise Didier , Milpied Noel , Deconinck Eric , Cordonnier Catherine , Cornillon Jerome , Contentin Nathalie , Guillerm Gaelle , Fegueux Nathalie , Turlure Pascal , Salmon Alexandra , de Revel Thierry , Mohty Mohamad 
Published: October 2019

Abstract
Abstract 2008
T prolymphocytic (T-PLL) is a rare aggressive mature T cell disorder with distinctive clinical, morphologic, immunophenotypic and cytogenetic characteristics. The median overall survival (OS) is approximately 7 months with conventional chemotherapy. The introduction of the anti-CD52 monoclonal antibody, alemtuzumab, allowed for an improved overall response rate around 75% with a CR rate of 60% and a median OS of 10 months. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is currently the only potentially active option to consolidate response to initial chemo-immunotherapy in those eligible patients.
We retrospectively studied all patients fulfilling the requirements for P-TLL diagnosis and who underwent allo-HSCT reported to the “Société Française de Greffe de Moelle et de Thérapie Cellulaire” (SFGM-TC) registry. Twenty patients were identified from 14 SFGM-TC centers from 2000 to 2010 (median year, 2009). Prior to allo-HSCT, 9 patients were in CR, 8 in PR, 3 refractory or in progression. Alemtuzumab was used in 17 patients prior to transplant. Following transplantation, as best response, 17 patients were in CR while 1 progressive patient became partial responder. For two patients, response could not be determined due to early transplant-related mortality (TRM). Engraftment was achieved in 96% of the patients. Eleven patients developed acute GVHD (grade I, n=1; grade II, n=2; grade III, n=2; and grade IV, n=1). The cumulative incidence of grade II to IV GVHD was 52% (95%CI: 29–70%). Chronic GVHD was observed in 45% of the patients, with 4 having a limited form and 5 an extensive form. With a median follow-up of 28.8 months (range 6.8–103) for surviving patients, 10 patients are alive with 7 of them being in CR. The KM estimates of OS and progression-free survival (PFS) at 3 years were 41.7 (95%CI: 18–62%) and 29% (95%CI: 14–50%), respectively. The cause of death among the 10 patients was transplant related in 6 and due to disease progression in 4. The relapse incidence was 51%. Relapse was observed at a median of 14 months (range, 2–24) after allo-HSCT. Among the eight relapses, four occurred during the second year. TRM incidence was 38 % at 3 years. Though not statistically significant due to the relatively low number of patients, the use of TBI in the conditioning regimen was associated with a better PFS.
We conclude that allo-HSCT may allow long term survival in some patients with T-PLL following induction treatment. Given the rarity of this disease, national and international collaborations (e.g. registry) are needed to further clarify the role of allo-HSCT and natural history of this rare and fatal disease.

Disclosures:
No relevant conflicts of interest to declare.