Exicure Announces Phase 2 Trial Results for Multiple Myeloma Treatment

Exicure announced results from its completed Phase 2 trial evaluating burixafor in combination with propranolol and granulocyte colony-stimulating factor for the mobilization of hematopoietic progenitor cells in patients with multiple myeloma undergoing autologous hematopoietic cell transplantation. The data, which showed that approximately 90% of study participants achieved the primary endpoint, were presented in an oral session at the 67th American Society of Hematology annual meeting in Orlando, Florida. Burixafor is an investigational small molecule that blocks CXCL12 binding to CXCR4 receptors on HPCs, rapidly mobilizing these cells from the bone marrow into the peripheral blood. In preclinical studies, propranolol enhanced burixafor-induced mobilization by inhibiting the ss2-adrenergic receptor. In the open-label, multicenter Phase 2 trial, 17 of 19 participants achieved the primary endpoint. Two required another session to achieve 2x106 CD34+ cells/kg. Among participants who proceeded to transplant, the median time to neutrophil engraftment was 13 days, and the median time to platelet engraftment was 17.5 days. Burixafor has a differentiated and rapid mobilization kinetics, with peak peripheral levels of CD34+ cells observed within one hour of administration. This distinguishes it from other CXCR4 inhibitors and allows for same day burixafor administration and apheresis. Notably, 16 of 19 participants had prior exposure to daratumumab, a therapy associated with reduced mobilization, yet 14 of those 16 participants achieved the primary endpoint, including 12 of 14 participants who had received both daratumumab and lenalidomide. Longer intervals between the last dose of daratumumab and leukapheresis were associated with higher CD34+ cell yields. Burixafor administered in combination with propranolol and G-CSF was well tolerated and demonstrated an excellent safety profile. There were no burixafor-related adverse events higher than Grade 2.