In a recent study, researchers reported positive outcomes for graft vs host disease (GVHD) and GVHD-related relapse-free survival (GRFS) outcomes after myeloablative conditioning with the use of the cell-therapy product, Orca-T. Study results were reported at the Annual Meeting of the Society of Hematologic Oncology (SOHO) by Samer A. Srour, MBChB, MS, of the University of Texas MD Anderson Cancer Center in Houston, Texas, and colleagues.

Orca-T is an allogeneic, cell-based, investigational product designed to have an optimized composition of conventional and regulatory T cells. Orca-T was given to patients with high-risk hematologic malignancies across 2 trials in this analysis, which included a single-center phase 1/2 study (34 patients) and a multicenter phase 1b study (103 patients).

In patients receiving Orca-T, myeloablative conditioning was followed by GVHD prophylaxis using single-agent tacrolimus. A Center for International Blood and Marrow Transplant Research (CIBMTR) control cohort of 375 patients was also evaluated for comparisons, and these patients had received prophylaxis with tacrolimus and methotrexate.


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Median patient ages were 42 years in patients from the single-center phase 1/2 trial with Orca-T, 51 years in patients in the multicenter phase 1b trial with Orca-T, and 52 years in patients of the CIBMTR control cohort. A wide range of hematologic malignancies was represented among patients in this analysis.

The median follow-up times were 367 days for the phase 1/2 Orca-T cohort, 313 days for the phase 1b Orca-T cohort, and 900 days for the CIBMTR control cohort. With Orca-T, the time from the end of apheresis to delivery at the transplant center was reported to be consistently below 72 hours. Additionally, neutrophil engraftment occurred at a median time of 13 days after transplant, and platelet engraftment occurred at a median of 16 days post-transplant.

Grade 3 or higher acute GVHD was reported in 4% (95% CI, 0%-20%) of patients from Orca-T cohorts, compared with 16% (95% CI, 12%-19%) in the CIBMTR control cohort. Moderate-to-severe chronic GVHD at 1 year was reported in 5% of patients from the Orca-T cohorts, compared with 38% in the CIBMTR cohort. The rate of severe infections was reportedly 10% across Orca-T cohorts.

The 1-year relapse rate was 20% among patients in Orca-T cohorts, and it was 35% in the CIBMTR cohort. The 1-year rates of GRFS were 71% in Orca-T cohorts and 21% in the CIBMTR cohort. Among patients in Orca-T cohorts, the 1-year nonrelapse mortality rate was 4%. The 1-year overall survival rates were 90% in the Orca-T cohorts and 68% in the CIBMTR cohort.

Dr Srour also indicated that the choice of conditioning regimen may influence disease control in patients treated with Orca-T, with better relapse-free survival outcomes in this study seen for those receiving busulfan/fludarabine/thiotepa.

Dr Srour concluded that in this analysis, excellent results were obtained with GRFS and GVHD outcomes, and in terms of infection rates. He also explained that a pivotal phase 3 randomized trial evaluating Orca-T is currently enrolling.

Disclosures: Some co-authors listed for this abstract are employees of Orca Bio.

Reference

Meyer E, Pavlova A, Gandhi A, et al. Orca-T, a precision engineered allograft, results in high GVHD-free and relapse-free survival following myeloablative conditioning for hematological malignancies. Presented at: Annual Meeting of the Society of Hematologic Oncology (SOHO); September 28-October 1, 2022. Abstract CT-524.