The addition of RGI-2001, an invariant natural killer cell activator, to a calcineurin inhibitor and methotrexate or mycophenolate mofetil demonstrated promising efficacy for the prevention of acute graft vs host disease (GVHD), according to the results of the phase 2b RGI-2001-003 study presented at the 2023 Tandem Transplantation and Cellular Therapy Meetings of ASTCT and CIBMTR.

The open-label, phase 2b RGI-2001-003 study treated 49 patients who underwent myeloablative allogeneic hematopoietic cell transplant to receive RGI-2001 plus calcineurin inhibitor and methotrexate or mycophenolate mofetil. The primary endpoint was grade II-IV acute GVHD by day 100. The graft source was HLA-matched in 90% of cases and was most commonly from peripheral blood (82%).

The median age at baseline was 52. The majority of patients had acute myeloid leukemia at 53%, followed by 22% with acute lymphoblastic leukemia, 16% with myelodysplastic syndrome, and 8% with chronic myeloid leukemia, CMML, or MPD. Nearly all patients received methotrexate as part of their prophylaxis regimen.

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By day 100, 20.4% of patients developed grade II-IV acute GVHD. Of these cases, 2 were grade III-IV and 1 patient died.

The overall survival at 180 days was 93.9%. The grades II-IV and grades III-IV acute GVHD-free survival was 75.5% and 91.8%, respectively.

The most common treatment-related treatment-emergent adverse events of any grade included stomatitis, diarrhea, and nausea. One infection was reported with respiratory syncytial virus.

The authors concluded that “the efficacy and safety of RGI-2001 is favorable and has the potential to provide breakthrough therapy for acute GVHD prevention.” The authors indicated that a phase 3 study is planned.

Disclosures: This study was supported in part by the Regimmune Corporation. Please see the original reference for a full list of disclosures.


Chen Y-B, Farhan S, Lekakis L, et al. Efficacy of the addition of RGI-2001 to tacrolimus and methotrexate for acute Gvhd prevention in myeloablative HSCT using HLA-matched donors. Presented at: 2023 Tandem Meetings Transplantation and Cellular Therapy Meetings of ASTCT and CIBMTR; February 15-19, 2023. Abstract 326.