Impact of First- and Second-Generation Tyrosine Kinase Inhibitors on the Development of Graft-Versus-Host Disease in Individuals with Chronic Myeloid Leukemia: A Retrospective Analysis on behalf of the Polish Adult Leukaemia Group

Background: The implementation of tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML) has brought a significant improvement in the prognosis for CML patients and a decrease in the number of patients requiring allogeneic hematopoietic stem cell transplantation (allo-HCT). Nevertheless, the impact of TKIs on allo-HCT outcomes have not been thoroughly explored. Objectives: The main endpoint of our research was to assess the impact of prior TKI treatment on acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD). Methods: In our retrospective analysis we included 240 patients treated between 1993 and 2013, and divided them into 3 groups according to the therapy administered prior to matched related or matched unrelated donor allo-HCT (imatinib group n=41, dasatinib/nilotinib group n=28, TKI naïve group n=171). Results: Both the cumulative incidence of aGvHD (p=0.044) and cGvHD (p<0.001) in individuals receiving second generation TKIs (2G-TKIs) prior to allo-HCT compared to patients receiving no TKIs or imatinib (IMA) (40.7% vs 61.4% vs 70.7%, p=0.044; 25.0% vs 76.4% vs 51.2%, p<0.001, respectively). In case of the 2G-TKI cohort, the number of low-grade aGvHD and cGvHD was significantly lower compared to the IMA and TKI-naïve groups (p=0.018, p=0.004; p<0.001 versus TKI-naïve, respectively). In terms of 3-year overall survival (OS) there were no important variations between TKI-naïve, IMA and 2G-TKI (55% vs 49.9% vs 69.6%, p=0.740). Conclusions: The results of our study suggest that TKI treatment prior to allo-HCT may have protective impact on immune-mediated outcomes.