---RGI-2001 for the Prophylaxis of Acute Graft-Versus-Host Disease Following Allogeneic HCT.

Abstract

RGI-2001, a liposomal glycolipid that binds CD1d receptor of antigen-presenting cells, can activate invariant natural killer T cells and stimulate cytokine-dependent proliferation of regulatory T-cells (Tregs). This open-label, single-arm, multicenter phase 2b trial evaluated the safety and efficacy of RGI-2001 in combination with standard graft-versus-host disease (GVHD) prophylaxis in participants receiving myeloablative allogeneic hematopoietic cell transplantation (HCT) for hematologic malignancies. RGI-2001 was infused at a dose of 100 ug/kg for six weekly doses starting on Day 0 of HCT. The primary endpoint was grades II-IV acute GVHD by Day 100 after HCT. Forty-nine participants received RGI-2001 in combination with tacrolimus and methotrexate. RGI-2001 was well tolerated, with no serious infusion reactions. Sixteen participants experienced grade ≥3 treatment-related adverse events, with the most common being decreased appetite, leukopenia, thrombocytopenia and stomatitis. The estimated probability of grades II-IV and III-IV acute GVHD were 24.9% and 4.1%, respectively. Compared to controls from the Center for International Blood and Marrow Research Transplant registry, participants receiving RGI-2001 experienced superior clinical outcomes, including Day-180 grades II-IV acute GVHD-free survival (70.8% vs 50.7%, adjusted hazard ratio 0.45, 95% CI 0.30-0.68). Increasing NKT and Treg populations were observed after HCT, consistent with the proposed action of RGI-2001. In conclusion, RGI-2001 was well tolerated and was associated with low rates of acute GVHD and encouraging survival after myeloablative HCT. These results support strategies that target NKT and Treg cell populations to augment immunological changes in allogeneic HCT recipients. This trial was registered at www.clinicaltrials.gov as NCT04014790.