Immunological effects of nilotinib prophylaxis after allogeneic stem cell transplantation in patients with advanced chronic myeloid leukemia or philadelphia chromosome-positive acute lymphoblastic leukemia

// Nira Varda-Bloom 1, 2, * , Ivetta Danylesko 1, 2, * , Roni Shouval 1, 2, 3, 4 , Shiran Eldror 1, 2 , Atar Lev 1, 2, 5, 6 , Jacqueline Davidson 1, 2 , Esther Rosenthal 1, 2 , Yulia Volchek 1, 2 , Noga Shem-Tov 1, 2 , Ronit Yerushalmi 1, 2 , Avichai Shimoni 1, 2 , Raz Somech 1, 2, 5, 6 , Arnon Nagler 1, 2 1 Sheba Medical Center, Ramat-Gan, Israel 2 Sackler Faculty of Medicine, Tel-Aviv University, Israel 3 Dr. Pinchas Bornstein Talpiot Medical Leadership Program, Sheba Medical Center, Israel 4 Bar-Ilan University, Ramat Gan, Israel 5 Pediatric Immunology Service, Jeffrey Modell Foundation, USA 6 Edmond and Lily Safra Children’s Hospital, Israel * These authors contributed equally to this work Correspondence to: Ivetta Danylesko, email: alexivetta@gmail.com Keywords: nilotinib, stem cell transplantation, immune reconstitution, mitogens, thymic activity Received: September 30, 2016      Accepted: November 08, 2016      Published: November 18, 2016 ABSTRACT Allogeneic stem cell transplantation remains the standard treatment for resistant advanced chronic myeloid leukemia and Philadelphia chromosome–positive acute lymphoblastic leukemia. Relapse is the major cause of treatment failure in both diseases. Post-allo-SCT administration of TKIs could potentially reduce relapse rates, but concerns regarding their effect on immune reconstitution have been raised. We aimed to assess immune functions of 12 advanced CML and Ph+ ALL patients who received post-allo-SCT nilotinib. Lymphocyte subpopulations and their functional activities including T-cell response to mitogens, NK cytotoxic activity and thymic function, determined by quantification of the T cell receptor (TCR) excision circles (TREC) and TCR repertoire, were evaluated at several time points, including pre-nilotib-post-allo-SCT, and up to 365 days on nilotinib treatment. NK cells were the first to recover post allo-SCT. Concomitant to nilotinib administration, total lymphocyte counts and subpopulations gradually increased. CD8 T cells were rapidly reconstituted and continued to increase until day 180 post SCT, while CD4 T cells counts were low until 180−270 days post nilotinib treatment. T-cell response to mitogenic stimulation was not inhibited by nilotinib administration. Thymic activity, measured by TREC copies and surface membrane expression of 24 different TCR Vβ families, was evident in all patients at the end of follow-up after allo-SCT and nilotinib treatment. Finally, nilotinib did not inhibit NK cytotoxic activity. In conclusion, administration of nilotinib post allo-SCT, in attempt to reduce relapse rates or progression of Ph+ ALL and CML, did not jeopardize immune reconstitution or function following transplantation.