Assessment of the Effect of Nilotinib (Tasigna) Maintenance Therapy After Allogeneic Stem Cell Transplantation in Patients with Advanced CML and Ph+ ALL On Immune Reconstitution and Lymphocyte Function

TKIs are known to affect T and NK cells. We therefore assessed immunological reconstitution and function in 24 pts with advanced CML and Ph+ ALL who received Nicotinib as maintenance therapy post alloSCT (study CAMN107AIL03T). At 6 months after alloSCT, 11 of 15 pts with advanced CML had attained CCyR, 11 of 15 pts with advanced CML had attained a MMR or better, and 5 of 7 pts with Ph+ ALL attained a CR. The median OS was 16 months, with predicted 1- and 2- year rates of 55% (95% CI, 32% – 72%) and 50% (95% CI, 28% – 68%), respectively. The median PFS was 11 months, with predicted 1- and 2- year rates of 50% (95% CI, 28% – 68%) and 38% (95% CI, 17% – 59%), respectively. Immunological testing was performed pre- and post Nilotinib maintenance therapy in 12 pts in this study. The relative percentage of T- lymphocyte subsets (assessed by FACS) and total lymphocytes number were stable during Nilotinib maintenance therapy, while a 7.8±2.5 fold increase in B cells was noted. T cell mitogenic response with αCD3 and PHA (stimulation index ratio) was sustained (2.5±1.0, vs. 2.8±1.05 and 3.3±1.3 vs. 5.3±2.9 stimulation. Mean thymic output determined by TREC quantification pre-, during and post Nilotinib administration was 81.8±108, 81.2±90.3 and 142.8±197.4 copies per 0.5ug DNA indicating continuous thymopoiesis. Similarly, no significant change of the TCR repertoire was observed during Nilotinib treatment. Normal expression of the TCR repertoire was detected in 15.1±5.5 and 15.3±5.6 of the examined TCRs. NK cytotoxic activity against K562 expressed as fold of change from baseline, also remained stable during Nilotinib treatment (2.8±1.1 and 2.3±0.8, respectively). In summary, Nilotinib maintenance therapy post alloSCT  in pts with  advanced CML and Ph+ALL did not interfere or jeopardized  immune reconstitution and function.