Donor KIR haplotype B improves progression-free and overall survival after allogeneic hematopoietic stem cell transplantation for multiple myeloma

Allogeneic hematopoietic stem cell transplantation from related or unrelated donor has become a standard treatment for many patients with hematological malignancies, but the role of this treatment approach in the treatment of multiple myeloma remains controversial, as high risk of relapse remains a major concern.1 In acute leukemias, especially acute myeloid leukemias, alloreactive donor-derived natural killer cells (NK cells) have been correlated with an improved survival, especially after T-cell-depleted transplant procedures such as haploidentical stem cell transplantation.2 Small reports after allogeneic stem cell transplantation for multiple myeloma as well as pre-clinical models showed that alloreactive NK cells might have a role regarding cytotoxicity and relapse prevention in multiple myeloma.3 The NK cell function is determined by several receptor families including activating and inhibitory killer cell immunoglobulin-like receptors (KIRs). For the majority, especially for the active KIRs, the correspondent ligands are unknown.