Management of tyrosine kinase inhibitors and donor lymphocyte infusions post transplantation for chronic myeloid leukemia: a survey of contemporary practice on behalf of the chronic malignancies working party of the EBMT.

The landscape of Allogeneic Haematopoietic Cell Transplantation (allo-HCT) for Chronic Myeloid Leukaemia (CML) remains dynamic with the advent of tyrosine kinase inhibitors (TKIs). There remains an absence of widely agreed evidence-based guidelines for post-transplant monitoring and relapse management. To evaluate current real-world practices for 'high risk' CML, the CML subcommittee of the Chronic Malignancies Working Party (CMWP) of the European Blood and Marrow Transplantation (EBMT) society developed an electronic survey, which was distributed to 39 EBMT-registered transplant centres in April 2024. Centres were chosen based on CML allo-HCT activity. Twenty-three centres (59%) responded, providing clinical perspectives into pre-transplant chemotherapy regimens, TKI use, ABL1 kinase domain mutation analysis, post-transplant monitoring, and their practice regarding sequencing/ integration of TKIs with donor lymphocyte infusions (DLI). Most centres conduct monthly BCR::ABL1 transcript monitoring during the first three months post-transplant, transitioning to quarterly assessments upon achieving a deep molecular response. TKI maintenance is widely adopted across centres, with treatment duration guided by molecular response, and TKIs are generally preferred over DLI for managing molecular relapse. However, DLI remains a valid option for TKI-refractory chronic-phase (CP)-CML relapse. Survey findings illustrate significant heterogeneity in practice, offering insights to inform research aimed at improving allo-HCT outcomes in CML.