Exicure's Burixafor Shows Impressive Mobilization Results; Stock Rallies Following Multiple Myeloma Trial Data

Exicure Inc. (XCUR) witnessed substantial investor enthusiasm overnight, with shares climbing over 65% to $8.69 following encouraging phase 2 trial outcomes for Burixafor in multiple myeloma presented at the ASH Annual Meeting. The compound demonstrated notable efficacy in mobilizing CD34+ hematopoietic stem cells, a critical component of autologous stem cell transplantation therapy.

Understanding the Clinical Challenge

Multiple myeloma, a rare malignancy affecting plasma cells in bone marrow, necessitates autologous hematopoietic cell transplantation (AHCT) as standard-of-care treatment in the United States. The procedure requires successful extraction and collection of patients’ own hematopoietic progenitor cells (HPCs) from peripheral blood. Effective mobilization—the process of moving these cells from bone marrow into the bloodstream—directly impacts transplant success rates and subsequent patient recovery timelines.

Trial Outcomes and Performance Metrics

Burixafor, an experimental small molecule CXCR4 antagonist, was evaluated for its capacity to rapidly mobilize CD34+ cells when combined with propranolol and granulocyte colony-stimulating factor. The phase 2 study’s primary endpoint examined whether participants could collect at least 2 × 10⁶ CD34+ cells per kilogram of body weight within two leukapheresis sessions.

Results proved compelling: 89.5% of participants (17 of 19) achieved the primary endpoint in two sessions, while the remaining two required a third collection procedure. For transplant recipients, median neutrophil engraftment occurred within 13 days, with platelet recovery reaching safe levels by day 17.5—metrics that carry significant implications for 100 days after stem cell transplant, when immunologic recovery becomes increasingly important for long-term outcomes.

Differentiated Mechanism and Speed Advantage

A key distinction of Burixafor lies in its mobilization kinetics. Peak CD34+ peripheral concentrations were observed within one hour of administration, enabling same-day treatment and apheresis collection. This rapid response contrasts with existing FDA-approved CXCR4 antagonists such as plerixafor and motixafortide, which typically require overnight pre-treatment protocols.

Market Context

The positive trial readout generated immediate market recognition. XCUR closed the prior trading session at $5.33, representing a 3.50% gain before the ASH presentation catalyzed the overnight advance. The results position Burixafor as a potentially differentiated mobilization agent for the multiple myeloma transplantation segment.