Optimizing Outcomes with Myeloablative Conditioning in Older Patients: Efficacy and Safety of Precision Engineered Orca-T in Patients > 55 Years Old with Hematologic Malignancies

Background Allogeneic hematopoietic stem cell transplants (alloSCT) offer the only curative treatment for many hematological cancers but carry the risk of significant toxicity including graft versus host disease (GvHD). Additionally, while the use of a myeloablative conditioning (MAC) regimen optimizes disease control, it can increase the complications associated with transplant and non-relapse mortality. Therefore, older patients are often deemed unfit for MAC and relegated to treatment with reduced intensity conditioning (RIC) regimens, which result in a higher incidence of relapse. Orca-T is a high-precision cell therapy biologic that includes stem and immune cells, derived from allogeneic donors, that leverages highly purified, polyclonal donor regulatory T cells to control alloreactive immune responses. The specific subsets selected in the Orca-T manufacturing process retain cells with therapeutic benefit while removing those that pose potential risks, allowing for intensification of concomitant chemotherapy and resulting in overall positive outcomes to date in the phase 1b trial (NCT04013685). To assess the safety and efficacy in an older patient population, we compared outcomes in those at least 55 years old to younger patients treated with Orca-T, receiving chemotherapy-based MAC with tacrolimus as single-agent GvHD prophylaxis. Methods As of 6/02/23, 38 patients ≥18 to