Burixafor Demonstrates Strong Efficacy in Multiple Myeloma Mobilization Study; Exicure Stock Rallies

Exicure Inc. (XCUR) shares surged approximately 65% to $8.69 in after-hours trading following the company’s presentation of encouraging phase 2 clinical data for Burixafor at the ASH Annual Meeting. The investigational therapeutic represents a significant advancement in stem cell mobilization for patients with multiple myeloma undergoing autologous hematopoietic cell transplantation (AHCT).

Understanding Burixafor’s Mechanism and Clinical Application

Burixafor functions as a small molecule CXCR4 antagonist, blocking CXCL12 binding to receptors on hematopoietic progenitor cells (HPCs). This mechanism effectively triggers the rapid mobilization of these cells from bone marrow into peripheral circulation. The phase 2 trial evaluated Burixafor when administered alongside propranolol—a compound whose structure enables beta-adrenergic blocking properties—and granulocyte colony-stimulating factor to enhance CD34+ hematopoietic stem cell mobilization. This combined approach aims to improve the efficiency of cell collection via leukapheresis for transplant candidates.

Multiple Myeloma: Disease Context and Treatment Standards

Multiple myeloma, also known as Kahler’s disease, is a hematologic malignancy affecting bone marrow plasma cells. The disease disrupts normal hematopoiesis, compromises immune function, and frequently leads to skeletal damage and renal dysfunction. In the United States, newly diagnosed patients typically receive autologous stem cell transplantation following high-dose chemotherapy as standard treatment protocol. The procedure requires collecting patients’ own hematopoietic cells from peripheral blood—a process necessitating prior mobilization of stem cells from bone marrow reserves into circulation.

Trial Results and Mobilization Kinetics

The study’s primary objective assessed whether participants could collect a minimum of 2 × 10⁶ CD34+ cells per kilogram of body weight within two leukapheresis sessions. Results demonstrated that 17 of 19 participants (89.5%) achieved this endpoint following the initial two collections, while the remaining two required a third session. Among transplant recipients, median neutrophil engraftment occurred at 13 days post-procedure, with median platelet recovery reaching safe levels at 17.5 days.

A distinguishing feature of Burixafor involves its rapid mobilization kinetics compared to established CXCR4 inhibitors. Peak CD34+ cell peripheral concentrations emerged within one hour of administration, enabling same-day administration and apheresis procedures. This contrasts sharply with currently FDA-approved alternatives such as plerixafor and motixafortide, which require overnight pre-treatment regimens before leukapheresis can commence.

Market Implications and Stock Performance

The positive trial readout drove significant investor enthusiasm. XCUR closed the prior trading session at $5.33 (up 3.50%) before the overnight surge. The rapid mobilization profile and high collection success rate position Burixafor as a potentially differentiated therapeutic option within the stem cell mobilization landscape, potentially reshaping treatment protocols for multiple myeloma patients requiring transplantation.