Exicure, Inc. (XCUR) posted an impressive Tuesday session, with shares trading significantly higher on volume of 13.62 million compared to its typical 151,410 shares. The catalyst? Phase 2 trial results that could reshape how doctors prepare multiple myeloma patients for transplants.
The biotech company presented data at the 67th American Society of Hematology Annual Meeting showing its burixafor (GPC-100) combination therapy hit the mark for nearly all participants. When combined with propranolol and granulocyte colony-stimulating factor, burixafor helped mobilize hematopoietic progenitor cells in patients preparing for autologous hematopoietic cell transplantation.
Here's what makes this interesting: burixafor works by blocking CXCL12 from binding to CXCR4 receptors on these progenitor cells, essentially coaxing them out of the bone marrow and into peripheral blood where they can be collected. Think of it as convincing cells to leave their comfortable home and venture into the bloodstream.
The Numbers That Matter
Out of 19 trial participants, 17 achieved the primary endpoint of collecting at least 2 × 10⁶ CD34+ cells per kilogram within just two leukapheresis sessions. That's an 89.5% success rate. The remaining two participants needed one additional session to reach the target.
The speed here is notable. Burixafor demonstrated peak peripheral levels of CD34+ cells within one hour of administration. This rapid mobilization kinetics distinguishes it from other CXCR4 inhibitors and allows doctors to administer burixafor and perform apheresis on the same day.
For patients who proceeded to transplant, the median time to neutrophil engraftment was 13 days, with platelet engraftment following at a median of 17.5 days.
Performance Where It Counts
Perhaps the most compelling aspect of this data involves patients with prior exposure to daratumumab, Johnson & Johnson's (JNJ) therapy sold under the brand names Darzalex and Darzalex Faspro. Daratumumab is associated with reduced mobilization, which typically makes cell collection more challenging.
Yet 16 of the 19 participants had received daratumumab previously, and 14 of those 16 still achieved the primary endpoint. Even among the 14 participants who had received both daratumumab and lenalidomide, 12 hit their targets. Those are success rates of 87.5% and 85.7% respectively in populations where mobilization is typically harder.
The data also revealed that longer intervals between the last daratumumab dose and leukapheresis correlated with higher CD34+ cell yields, suggesting timing matters when planning treatment sequencing.
Preclinical work showed that propranolol enhanced burixafor's mobilization effects by inhibiting the β2-adrenergic receptor. That combination appears to be paying off in human trials.
Safety Profile
On the safety front, the burixafor combination was well tolerated with no adverse events exceeding Grade 2, which is exactly what you want to see in a treatment that needs to work quickly without causing significant complications.
Price Action: XCUR stock climbed 63.23% to $8.70 in Tuesday trading.
