Orca-T vs allogeneic hematopoietic stem cell transplantation (Precision-T): a multicenter, randomized phase 3 trial

E Everett H. Meyer (1Division of Blood and Marrow Transplantation and Cellular Therapy, Department of Medicine, Stanford University, Stanford, CA) A Amandeep Salhotra (2Division of Leukemia, Department of Hematology & Hematopoietic Cell Transplantation, City of Hope, Duarte, CA) A Arpita P. Gandhi (3Center for Hematologic Malignancies, Knight Cancer Institute, Oregon Health and Science University, Portland, OR) J Jeremy Pantin (4Sarah Cannon Transplant and Cellular Therapy Program at TriStar Centennial Medical Center, HCA Healthcare, Nashville, TN) S Sagar S. Patel (15Huntsman Cancer Institute, The University of Utah, Salt Lake City, UT) R Rasmus T. Hoeg (34Division of Malignant Hematology/Cellular Therapy and Transplantation, Department of Internal Medicine, University of California Davis, Sacramento, CA) A Alexandra Gomez-Arteaga (7Weill Cornell Medicine, New York, NY) R Rawan Faramand (24Moffitt Cancer Center and Research Institute, Tampa, FL) R Roni Tamari (9Adult Bone Marrow Transplant Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY) E Edmund K. Waller S Satyajit Kosuri (11Division of Hematology and Oncology, University of Chicago Medicine, Chicago, IL) A Antonio M. Jimenez Jimenez (12Division of Transplantation and Cell Therapy, University of Miami Sylvester Comprehensive Cancer Center, Miami, FL) J Jennifer Holter-Chakrabarty (13Transplant & Cellular Therapy Clinic, OU Health Stephenson Cancer Center, Oklahoma City, OK) B Bhagirathbhai Dholaria Y Yi-Bin Chen (1Cellular Immunotherapy Program, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA) B Betty K. Hamilton (16Blood and Marrow Transplant Program, Cleveland Clinic, Cleveland, OH) J John Magenau (University of Michigan) A Alireza Eghtedar (18Colorado Blood Cancer Institute, HCA HealthONE Presbyterian St. Luke's, Denver, CO) J Joshua M. Murray (19Orca Bio, Menlo Park, CA) A Anna Pavlova N Nathaniel B. Fernhoff (19Orca Bio, Menlo Park, CA) J James Scott McClellan (19Orca Bio, Menlo Park, CA) M M. Scott Killian (19Orca Bio, Menlo Park, CA) A Ai Li R Robert S. Negrin (Stanford University Medical Center, Stanford, California, United States) C Caspian Oliai

Abstract

Abstract To prevent graft-versus-host disease (GVHD) in patients undergoing myeloablative allogeneic hematopoietic stem cell transplantation (alloHSCT), a calcineurin inhibitor plus methotrexate is routinely used. Early phase studies suggested improved outcomes with Orca-T, an allogeneic T-cell immunotherapy that uses purified donor regulatory T cells to prevent GVHD with significantly less immunosuppression. This phase 3 trial randomized adult patients (N = 187) with acute leukemias or myelodysplastic syndrome undergoing myeloablative conditioning to receive either Orca-T with tacrolimus or a conventional allograft with tacrolimus and methotrexate (Tac/MTX), using granulocyte colony-stimulating factor–mobilized peripheral blood from HLA-matched donors. The primary end point was survival free from moderate-to-severe chronic GVHD (cGVHD; cGFS). Using a stratified log-rank test, cGFS was significantly higher in the Orca-T arm than in Tac/MTX (hazard ratio, 0.26; 95% confidence interval, 0.14-0.47; P< .001). One-year estimates were as follows: cGFS was 78.0% with Orca-T vs 38.4% with Tac/MTX; cumulative incidence of moderate-to-severe cGVHD was 12.6% with Orca-T and 44.0% with Tac/MTX (Gray test P< .001); overall survival was 93.9% with Orca-T vs 83.1% with Tac/MTX (P = .12); GVHD-free and relapse-free survival was 63.1% and 30.9% in the Orca-T and Tac/MTX arms (P< .001), respectively; nonrelapse mortality (NRM) was 3.4% with Orca-T vs 13.2% with Tac/MTX (P = .03). Orca-T met the primary end point of improved survival free from cGVHD compared with Tac/MTX prophylaxis and should be considered a new therapeutic option with low toxicity for GVHD prophylaxis. Moreover, significantly less toxicity was observed with Orca-T patients, including fewer serious infectious complications and less NRM. This trial was registered at www.clinicaltrials.gov as NCT05316701.

Article Details

Journal Blood
Volume / Issue Vol. 147, Issue 11
Published March 12, 2026
Pages 1168-1177
ISSN 0006-4971
Publisher Elsevier BV

Journal Info

Blood

Elsevier BV

ISSN: 0006-4971 Health Sciences

Authors (26)

E

Everett H. Meyer

1Division of Blood and Marrow Transplantation and Cellular Therapy, Department of Medicine, Stanford University, Stanford, CA

A

Amandeep Salhotra

2Division of Leukemia, Department of Hematology & Hematopoietic Cell Transplantation, City of Hope, Duarte, CA

A

Arpita P. Gandhi

3Center for Hematologic Malignancies, Knight Cancer Institute, Oregon Health and Science University, Portland, OR

J

Jeremy Pantin

4Sarah Cannon Transplant and Cellular Therapy Program at TriStar Centennial Medical Center, HCA Healthcare, Nashville, TN

S

Sagar S. Patel

15Huntsman Cancer Institute, The University of Utah, Salt Lake City, UT

R

Rasmus T. Hoeg

34Division of Malignant Hematology/Cellular Therapy and Transplantation, Department of Internal Medicine, University of California Davis, Sacramento, CA

A

Alexandra Gomez-Arteaga

7Weill Cornell Medicine, New York, NY

R

Rawan Faramand

24Moffitt Cancer Center and Research Institute, Tampa, FL

R

Roni Tamari

9Adult Bone Marrow Transplant Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY

E

Edmund K. Waller

S

Satyajit Kosuri

11Division of Hematology and Oncology, University of Chicago Medicine, Chicago, IL

A

Antonio M. Jimenez Jimenez

12Division of Transplantation and Cell Therapy, University of Miami Sylvester Comprehensive Cancer Center, Miami, FL

J

Jennifer Holter-Chakrabarty

13Transplant & Cellular Therapy Clinic, OU Health Stephenson Cancer Center, Oklahoma City, OK

B

Bhagirathbhai Dholaria

Y

Yi-Bin Chen

1Cellular Immunotherapy Program, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA

B

Betty K. Hamilton

16Blood and Marrow Transplant Program, Cleveland Clinic, Cleveland, OH

J

John Magenau

University of Michigan

A

Alireza Eghtedar

18Colorado Blood Cancer Institute, HCA HealthONE Presbyterian St. Luke's, Denver, CO

J

Joshua M. Murray

19Orca Bio, Menlo Park, CA

A

Anna Pavlova

N

Nathaniel B. Fernhoff

19Orca Bio, Menlo Park, CA

J

James Scott McClellan

19Orca Bio, Menlo Park, CA

M

M. Scott Killian

19Orca Bio, Menlo Park, CA

A

Ai Li

R

Robert S. Negrin

Stanford University Medical Center, Stanford, California, United States

C

Caspian Oliai