A Phase II, Open-Label Pilot Study to Evaluate the Hematopoietic Stem Cell Mobilization of TG-0054 Combined with G-CSF in 12 Patients with Multiple Myeloma, Non-Hodgkin Lymphoma or Hodgkin Lymphoma - an Interim Analysis

Background: TG-0054 (burixafor) is a potent and selective antagonist of human chemokine receptor CXCR4 that inhibits the binding of stromal-derived factor 1 (SDF-1). Interruption of the CXCR4/SDF-1 interaction prevents sequestration of CD34⁺ stem cells to the bone marrow and subsequently mobilizes these cells into the peripheral blood within 1 to 3 hours of drug administration.

Materials and Methods: An open-label, phase II pilot trial was conducted in patients with multiple myeloma (MM), non-Hodgkin’s lymphoma (NHL), or Hodgkin’s lymphoma (HL) to evaluate the safety and stem cell mobilization of TG-0054 in combination with G-CSF.  We planned to treat twelve patients with subcutaneous injections of 10 µg/kg/day G-CSF in the afternoon for 4 days. On the morning of Day 5, patients received 3.14 mg/kg TG-0054 and underwent large volume (18-24L) leukapheresis approximately 2 hours post-drug infusion. Patients were allowed by protocol to undergo leukapheresis for 1-5 days to obtain the predetermined target of ≥5.0 x 10⁶ CD34⁺cells/kg. 9 of 12 patients have been treated thus far with a plan to treat 3 additional patients.

Results:  A planned interim analysis revealed that 6 of the 9 patients treated thus far collected more than 10 x 10⁶ CD34⁺cells/kg in 1 leukapheresis session. 2 patients required 2 days to achieve the study endpoint, and 1 outlier patient who had received Revlimid only 1 week prior to peripheral blood CD34 analysis failed to mobilize stem cells until he was allowed 2 more weeks to recover from his Revlimid treatment. Burixafor was well tolerated, and there were no adverse events that were attributed to the drug. All of the patients engrafted promptly after melphalan (7 patients) or BEAM (2 patients) conditioning regimens.

Conclusion: Burixafor in combination with G-CSF is a potent and well-tolerated mobilizer of stem cells into the peripheral blood, and with the exception of 1 outlier, was able to mobilize >5.0 x 10⁶ CD34⁺ cells/kg in 1-2 leukapheresis sessions in all patients treated thus far (median 1 day). This contrasts with our historical controls that required a median of 2-3 days to achieve a collection of ≥5.0 x 10⁶ CD34⁺ cells/kg. A total of 12 patients will be treated on this pilot study. These encouraging results warrant the further testing of this drug in a larger randomized clinical trial.