Press release

Menlo Park, CA

Orca Bio Presents Encouraging Interim Clinical Data on Orca-Q in Haploidentical Allogeneic Hematopoietic Stem Cell Transplants at 64th ASH Annual Meeting

Orca-Q is Orca Bio’s investigational high-precision cell therapy designed to overcome the challenges of haploidentical allogeneic hematopoietic stem cell transplant (alloHSCT)

Interim multi-center Phase 1 clinical trial results show that Orca-Q improved graft-versus-host disease-free, relapse-free survival in haploidentical alloHSCT compared to standard of care, without the use of post-transplant cyclophosphamide

MENLO PARK, CA, Dec. 12, 2022 – Orca Bio, a late-stage biotechnology company developing high-precision cell therapies for the treatment of cancer, genetic blood disorders and autoimmune diseases, today announced that interim clinical data from its Phase 1 multi-center trial of its second investigational cell therapy, Orca-Q, were unveiled in an oral presentation at the 64th American Society of Hematology (ASH) Annual Meeting.

The data from the ongoing clinical trial show that Orca-Q reduced the incidence and severity of graft versus host disease (GvHD) and improved graft-versus-host disease-free, relapse-free survival (GRFS) rates in 26 patients matched to haploidentical allogeneic hematopoietic stem cell donors. Unlike standard of care haploidentical allogeneic stem cell transplant (alloHSCT), Orca-Q does not require post-transplant cyclophosphamide (PTCy).

“Patients and transplant physicians are in urgent need of a novel treatment option that improves the chances of survival and the quality of that survival. This is the key limitation of haploidentical transplant, which is currently the only treatment option for the vast majority of blood cancer patients in need of a transplant,” said Amandeep Salhotra, M.D., associate professor, Division of Leukemia, Department of Hematology and Hematopoietic Cell Transplantation, City of Hope. “These results suggest Orca-Q’s promise to overcome this serious challenge by offering a novel investigational high-precision cell therapy with the potential to significantly improve patient outcomes and reduce serious transplant-related risks.”

Orca-Q is an investigational high-precision cell therapy that is a proprietary composition of enriched CD34+ stem cells combined with specific T cell subsets. The findings presented at ASH are from patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), myelodysplastic syndromes (MDS) and chronic myeloid leukemia (CML) who were matched to haploidentical allogeneic donors, defined as matched across at least 4/8 but fewer than 7/8 human leukocyte antigen (HLA) loci. Historical controls from the literature of patients who received standard of care haploidentical alloHSCT with PTCy GvHD prophylaxis were used for comparison purposes1,2,3,4.

Interim results from the Phase 1 single-arm, open-label trial showed:

  • A reduction of grade 2-4 acute GvHD (aGvHD) at 6 months as compared to literature controls (13% vs 21-63%), with only one patient developing grade 3 aGvHD and no incidence of grade 4 aGvHD.
  • No patients experienced moderate-to-severe chronic GvHD (cGvHD), compared to 24%-33% in the literature control. There was only one case of mild cGvHD.
  • GRFS was 75% at one year after Orca-Q, which compares favorably to a GRFS of 46% in patients in the literature control.

Patients treated with Orca-Q also experienced a low adverse event profile, suggesting Orca-Q has the potential to offer a new treatment option for patients undergoing haploidentical alloHSCT.

Today, approximately 70% of blood cancer patients do not have access to a fully matched related donor. Haploidentical transplant, which uses healthy, blood-forming cells from a partially matched donor to replace the unhealthy ones, is one of the few treatment options currently available to those without a fully matched donor. However, its use remains significantly limited because of the conditioning regimens that are required. Haploidentical transplant patients receiving higher intensity myeloablative conditioning treatments have a higher risk of cGvHD post-transplant, while patients receiving lower intensity pre-transplant conditioning have a greater risk of relapse.

“These interim results from our second clinical program demonstrate Orca-Q’s potential to overcome the challenges of haploidentical alloHSCT by providing a solution with which patients and physicians may no longer have to compromise between the risk of relapse and the risk of GvHD,” said Scott McClellan, M.D., Ph.D., chief medical officer of Orca Bio. “This novel approach, along with our growing body of clinical evidence demonstrating Orca-T’s improved GvHD and relapse-free survival rates in patients with HLA-matched donors, underscore the potential of our high-precision platforms to deliver cell therapies that can greatly expand the number of patients who receive life-saving treatment, whether their donor is a full or partial match.”

The full presentation is available on

1 Gooptu, M, et al. Blood. 2021; 138 (3): 273–282.

2 Sanz, J, et al. J Hematol Oncol. 2020; 13:46.

3 Baker, M, et al. Biol Blood Marrow Transplant. 2016; 22; 2047-2055.

4 Sanz, J, et al. J Hematol Oncol. 2020; 13:46.

About Orca Bio

Orca Bio is a late-stage biotechnology company developing purified, high-precision cell therapies for the treatment of cancer, autoimmune diseases and genetic blood disorders. Our investigational therapies are designed to deliver better survival rates with dramatically fewer risks than the standard of care. At Orca Bio, we hope to not only replace patients' blood and immune systems with healthy ones, but restore their quality of life. For more information, visit and follow Orca Bio on Twitter: @orcabio.


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