MENLO PARK, CA, December 8, 2025 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced positive new data from its pipeline of allogeneic T-cell immunotherapies at the 67th American Society of Hematology (ASH) Annual Meeting. 

Orca-Q with and Without the Use of GvHD Prophylaxis 

A subset of the multi-center Phase 1 clinical trial evaluated Orca-Q, Orca Bio’s second-generation investigational allogeneic T-cell immunotherapy, in patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), myelofibrosis (MF), myelodysplastic syndrome (MDS) and mixed phenotype acute leukemia (MPAL) with HLA-matched related and unrelated donors. New data evaluating Orca-Q with and without the use of pharmacological graft versus host disease (GvHD) prophylaxis showed encouraging outcomes including rapid neutrophil recovery and low rates of acute and chronic GvHD, relapse and non-relapse mortality (NRM).  

“Controlling alloreactivity and reducing GvHD following a conventional stem cell transplant typically requires multi-agent immunosuppression. However, this can impair immune reconstitution and increase the risk of organ toxicity, infection and relapse,” said presenting author Samer Srour, M.D., Department of Stem Cell Transplantation and Cellular Therapy, The University of Texas MD Anderson Cancer Center. “In these new findings, Orca-Q demonstrated encouraging outcomes even without the use of any pharmacological GvHD prophylaxis. While ongoing enrollment is important to further validate these results, the data suggest that Orca-Q may be able to control alloreactivity and potentially offer a platform to improve transplant outcomes through controlling GvHD and infection and reducing non-relapse mortality without increasing the risk of relapse.” 

Patients on Arm A received Orca-Q and single-agent tacrolimus (tac, n=18) while patients on Arm C received Orca-Q and no immune suppression (n=26). Median time to neutrophil engraftment was 15 days for patients who received tac and 11 days for patients who did not. Orca-Q was well-tolerated with 94% overall survival (OS) at one year for patients with tac and 87% for patients without tac. At one year, GvHD-and-relapse-free survival (GRFS) was 77% with tac and 79% without tac, and NRM was 6% and 0% with tac and without tac, respectively. Relapse-free survival (RFS) at one year was 88% with tac and 87% without tac. At Day 180, moderate-to-severe chronic GvHD was 12% with tac and 0% without tac. Grade 3-4 acute GvHD was 8% and 6% with and without tac, respectively. 

Importantly, Orca-Q patients treated without GvHD prophylaxis demonstrated more rapid immune reconstitution and improved control of infections. Specifically, BMT CTN Grade 2+ infections at one year were 33% with tac and 17% without tac.  

Orca-T and CAR-T Combination Treatment Versus Autologous CAR-T 

A second oral presentation compared the results from two separate Phase 1 trials in adults with high-risk relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL). The first trial evaluated OrCAR-T (n=16), a treatment that combines Orca-T and allogeneic CD19/CD22 CAR-T cells, and the second trial evaluated an autologous CD19/22 (n=17). At 18 months, progression-free survival (PFS) and OS were 100% and 100% with OrCAR-T, and 38.5% and 77% in the autologous cohort. Toxicities were mild across both cohorts, with no grade 3-4 CAR-related toxicities reported. At a median follow-up of 2.5 years, there were no relapses or patient deaths with OrCAR-T and seven deaths with autologous, six from refractory B-ALL.  

“Among adults with B-ALL, CAR-T therapy is often followed by a consolidative allogeneic transplant to achieve long-term remission,” said Lori Muffly, M.D., associate professor in the Division of Blood and Marrow Transplantation-Cellular Therapies at Stanford Health Care. “Emerging data showing improved progression-free survival in patients with a prior transplant has prompted interest in exploring whether combining a high-precision allogeneic therapy like Orca-T with CAR-T cells could provide a feasible, all-in-one treatment. While these findings are early, they suggest this approach has the potential to benefit patients across a range of hematologic diseases.” 

“Our team is encouraged by these new findings from our broader pipeline programs, including results that highlight the potential to eliminate the need for GvHD prophylaxis while preserving immune reconstitution with Orca-Q,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “The durability of Orca-T when combined with CAR-T therapy exemplifies how our high-precision approach may be applied to expand treatment options both within and beyond hematologic malignancies. Overall, these results reinforce our continued focus on advancing our pipeline to bring this high-precision platform to more patients who could potentially benefit.”