**Orca Bio Announces Orca-T® Phase 3 Data Published in Blood Demonstrate Significant Improvement in Survival Free from Chronic Graft versus Host Disease in Patients with Hematological Malignancies**

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Joshua Murray

Orca Bio Presents New Data at the 2026 Tandem Meetings of ASTCT® and CIBMTR® Reinforcing Orca-T® as a Durable, High-Precision Cell Therapy for Hematological Malignancies

New retrospective analysis showed Orca-T with reduced intensity conditioning (RIC) demonstrated favorable OS, RFS and GRFS compared to PTCy

Company announced first patients dosed in the Phase 2 SERENE-T study evaluating Orca-T with RIC

Orca-T demonstrated superior OS and RFS with reduced non-relapse mortality in patients with myelodysplastic syndromes compared to PTCy-based transplants

New manufacturing and distribution report found 100% of Orca-T products were distributed within 70 hours vein-to-vein time with consistent purity

Patients with haploidentical donors treated with Orca-Q® showed promising outcomes in survival, GVHD and relapse-free survival

MENLO PARK, CA, Feb. 5, 2026 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced new clinical data presented at the 2026 Tandem Meetings of ASTCT® and CIBMTR® from February 4-7 in Salt Lake City.

Orca-T with Reduced Intensity Conditioning

“Patients undergoing reduced intensity conditioning allogeneic stem cell transplantation often face a tradeoff between tolerability and long-term disease control,” said Caspian Oliai, MD, medical director of the UCLA Bone Marrow Transplantation Stem Cell Processing Center, and primary investigator on the SERENE-T Phase 2 study. “The clinical evidence being generated today, which suggests Orca-T may improve key outcomes by reducing GVHD without increasing infection risk or relapse rate, provides a strong foundation for our ongoing evaluation of Orca-T in this setting. The dosing of the first patients in the Phase 2 SERENE‑T study further strengthens this initial momentum, representing a meaningful step forward in expanding the investigation of Orca‑T for patients undergoing reduced intensity conditioning.”

SERENE-T (NCT07216443) is a new multicenter, open-label Phase 2 trial evaluating the safety, tolerability and efficacy of Orca-T, Orca Bio’s lead investigational allogeneic T-cell immunotherapy, in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) undergoing reduced intensity conditioning (RIC) or non-myeloablative conditioning (NMA). The first patients were treated this year at Vanderbilt University, UCLA and Oregon Health & Science University (OHSU) - Knight Cancer Institute. The study continues to enroll patients with plans to open at additional transplant centers across the U.S.

A new analysis compared outcomes from the single-center, open-label Phase 1 investigator-sponsored trial evaluating Orca-T versus a historical cohort of patients from the CIBMTR registry who received a conventional allogeneic hematopoietic stem cell transplant (alloHSCT) with post-transplant cyclophosphamide (PTCy). All patients were aged 60-75 (median 68 years), had a 7/8 or 8/8 human leukocyte antigen (HLA)-matched donor, and were given a RIC for the treatment of AML, acute lymphoblastic leukemia (ALL), MDS or myeloproliferative neoplasm (MPN).

Patients receiving Orca-T (n=53) compared with PTCy (n=587) demonstrated improved:

Overall survival at one year (OS; 88% vs 72%) and two years (84% vs 61%)
Relapse-free survival at one year (RFS; 82% vs 61%) and two years (79% vs 53%)
Graft-versus-host-disease relapse-free survival at one year (GRFS; 72% vs 54%) and two years (72% vs 45%)
Relapse rates at one and two years (9.7% vs 23%, 9.7% vs 30%) and non-relapse mortality at one and two years (NRM; 8% vs 16%, 12% vs 17%).

At one year, rates of Grade 3-4 acute and moderate-to-severe chronic graft versus host disease (aGVHD, cGVHD) were 0% and 10% with Orca-T, respectively, compared to 6% and 10% with PTCy. At two years, rates of cGVHD were 10% with Orca-T and 12% with PTCy.

Orca-T Versus PTCy in Patients with Myelodysplastic Syndromes

A post-hoc analysis of patients aged 18-65 with MDS compared pooled results from the Phase 3 Precision-T study and the Phase 1b study of Orca-T to a historical cohort from the CIBMTR registry of patients who received a conventional alloHSCT and PTCy in the myeloablative conditioning (MAC) HLA-matched setting. Patients with MDS who were treated with Orca-T (n=25) demonstrated higher one-, two- and three-year OS of 100% compared to the PTCy cohort (n=95) with 80%, 70% and 62%, respectively. At one year, the Orca-T arm showed RFS of 95% versus 64% with PTCy and NRM of 0% versus 9.9%, respectively. Notably, these trends were observed across subgroups including age and donor type.

A similar analysis was conducted across multiple hematologic malignancies, including MDS, AML and ALL with consistent results. In this post-hoc analysis, Orca-T (n=164) demonstrated higher OS compared to PTCy (n=380) at one, two and three years (94% vs 82%, 85% vs 73% and 82% vs 65%, respectively). At one year, RFS was 78% with Orca-T compared with 70% with PTCy, while NRM was 2.7% versus 7.7%, respectively. These findings were consistent with the results observed in a subgroup of patients over 50 years of age.

Reliable Manufacturing and Nationwide Distribution of Orca-T

A manufacturing and distribution analysis from the Phase 3 and Phase 1b Orca-T studies conducted between December 2019 and September 2024 reported on the production of 243 clinical cell therapies, including 215 from single-day and 28 from two-day collections. Overall, 100% of products were delivered to transplant centers across the U.S. within 70 hours, with 99% infused within 72 hours. Product quality was consistent across all three Orca-T components: hematopoietic stem cells, regulatory T-cells and conventional T-cells.

These results demonstrate the feasibility of reliably manufacturing and distributing Orca-T at scale while maintaining high product purity within a controlled logistics framework, supporting multicenter clinical studies and potential future commercial application.

“These data continue to reinforce the strength of Orca-T across both clinical outcomes and operational execution,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “The consistency of these results, along with our ability to reliably manufacture and deliver Orca-T across the U.S., highlights the potential of this therapy to make a meaningful difference for patients with hematologic malignancies. As we move toward a potential launch later this year, we remain focused on executing with the same level of commitment and rigor to support patients, clinicians and transplant centers.”

Orca-Q for Patients with Haploidentical Donors

New findings from the ongoing Phase 1 study of Orca-Q, Orca Bio’s second-generation investigational allogeneic T-cell immunotherapy, evaluated 39 patients with AML, ALL or MDS and a haploidentical donor who received MAC with Bu/Flu/Thiotepa (BFT), TBI/Flu/Thio (TFT) or TBI/Flu. All patients engrafted by Day +19 (median 11 days) and demonstrated encouraging rates of OS at one, two and three years (80%, 77% and 77%, respectively). Patients demonstrated RFS of 77% and GRFS of 72%, with low incidences of Grade 3-4 aGVHD at Day +180 and moderate-to-severe cGVHD at one year (8.1% and 0%, respectively). Outcomes were further improved in the TFT subgroup (n=14) across OS (85%), RFS (85%), GRFS (85%), aGVHD (0%) and cGVHD (0%).

About Orca-T

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Orca Bio Announces Orca-T® Phase 3 Data Published in Blood Demonstrate Significant Improvement in Survival Free from Chronic Graft versus Host Disease in Patients with Hematological Malignancies

**Orca Bio Announces Orca-T® Phase 3 Data Published in Blood Demonstrate Significant Improvement in Survival Free from Chronic Graft versus Host Disease in Patients with Hematological Malignancies**

Results from the Precision-T study showed Orca-T significantly improved survival free from chronic GvHD in patients with AML, ALL and MDS compared to a conventional allogeneic hematopoietic stem cell transplant

New findings demonstrate fewer rehospitalizations due to safety events and reduced rates of non-relapse mortality

Orca-T is the first Treg-based immunotherapy to demonstrate an improvement in patient outcomes including overall survival and GvHD and relapse-free survival (GRFS) in these conditions

Orca-T is being evaluated under Priority Review by the U.S. Food and Drug Administration (FDA) with a target action date of April 6, 2026

MENLO PARK, CA, Dec. 15, 2025 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced the publication of the Precision-T Phase 3 study results of its lead investigational allogeneic T-cell immunotherapy, Orca-T, in Blood, a journal of the American Society of Hematology (ASH). The study compared Orca-T to a conventional allogeneic hematopoietic stem cell transplant (alloHSCT) in patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), myelodysplastic syndrome (MDS) and mixed-phenotype acute leukemia (MPAL). These results were first presented on April 2, 2025, at the 51st Annual Meeting of The EBMT in Florence, Italy, and further analyses were presented at the 67th ASH Annual Meeting on December 6, 2025.

In the randomized Precision-T study, Orca-T plus single-agent tacrolimus (TAC) demonstrated a significant improvement in the primary endpoint of survival free from moderate-to-severe chronic graft versus host disease (cGFS) compared to alloHSCT plus tacrolimus/methotrexate (TAC/MTX). The rate for patients who received Orca-T was 78% (95% CI: 65%, 87%) compared to 38.4% (95% CI: 26%, 51%) for patients who received an alloHSCT (HR 0.26; p<0.00001), an improvement driven by a reduction in moderate-to-severe chronic graft versus host disease (cGvHD) and fewer patient deaths.

“Today, treating patients with serious blood cancers using conventional allogeneic stem cell transplants often forces a difficult risk–benefit trade-off, as clinicians work to cure the disease while avoiding life-threatening complications like GvHD,” said lead author Everett Meyer, M.D., Ph.D., hematologist and associate professor of medicine in Blood and Marrow Transplantation and Cellular Therapy at Stanford Medicine. “The Precision-T results showed that Orca-T can meaningfully shift that balance, delivering improved GvHD-free survival alongside less toxicity, including fewer serious infections and lower non-relapse mortality. Orca-T has the potential to become an important new therapy for patients and a valuable new option for the providers who care for them.”

In the study, all patients (n=187) with a median age of 43.6 years (range 19-65 years) were randomized 1:1 to Orca-T plus TAC or alloHSCT plus TAC/MTX. Patients across both groups received myeloablative conditioning and used a related or unrelated matched donor. Patients had a median follow-up time of 11.4 months (range 0.2-24.3 months) across both arms. Additional results from the Precision-T study at one year include:

A secondary endpoint of cumulative incidence of moderate-to-severe cGvHD was 12.6% (95% CI: 5%, 23%) and 44.0% (95% CI: 31%, 56%) in the Orca-T and alloHSCT arms, respectively (HR 0.19; p<0.00002).
The overall survival (OS), another secondary endpoint, was 93.7% (95% CI: 86%, 97%) in the Orca-T arm and 83.2% (95% CI: 73%, 90%) in the alloHSCT arm (HR 0.49; p=0.11823).
A secondary endpoint of GvHD and relapse-free survival (GRFS) was 63.1% and 30.9% with Orca-T and alloHSCT (p<0.001 in a post hoc analysis), respectively.
The cumulative incidence of non-relapse mortality (NRM) was 3.4% (95% CI: 0.9%, 8.8%) for Orca-T versus 13.2% (95% CI: 6.8%, 21.6%) for alloHSCT (HR 0.27 [95% CI: 0.08, 0.93]; p=0.03 in a post hoc analysis).

Additional safety findings were consistent with previous studies. The cumulative incidence for grade III or IV acute GvHD at day +180 was reduced with Orca-T with 6.2% (95% CI: 2.3, 12.9) versus 16.5% (95% CI: 9.4, 25.3) with alloHSCT (HR 0.37 [95% CI: 0.13, 1.02]; p=0.044 in a post hoc analysis). Grade 3+ infections were less common with Orca-T, with a one-year estimated incidence of 8.4% (95% CI: 3.6%, 16%) for Orca-T and 16.1% (95% CI: 9.2%, 25%) for alloHSCT.

An exploratory endpoint evaluated health-related quality of life (HRQoL) and hospitalization patterns and found Orca-T delivered marked improvements over conventional alloHSCT. In the data presented at ASH 2025, patients receiving Orca-T experienced faster recovery to, and higher improvement above, baseline HRQoL, fewer ICU stays, lower likelihood of rehospitalization and higher rehospitalization-free survival, suggesting better early post-treatment recovery and a lower burden of GvHD symptoms.

Rehospitalizations due to adverse events occurred less frequently among Orca-T recipients (27.3% [24] vs. 45.7% [43]), with fewer total hospitalization days per patient (30.6 vs. 40.8). Rehospitalization-free survival at 18 months was also significantly improved with Orca-T, reaching 66.4% (95% CI: 54.0, 76.2) compared to 33.8% (95% CI: 18.5, 49.9) for conventional alloHSCT (p=0.0096 in a post hoc analysis; HR 0.53 [0.32, 0.86]).

“As the first Treg-based immunotherapy to show improved outcomes for patients with acute leukemias and myelodysplastic syndrome compared with a conventional transplant, Orca-T has the potential to become a new standard of care,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “The Phase 3 results published in Blood underscore our ability to potentially redefine how blood cancers are treated today. We look forward to continuing to work closely with the FDA on the review of our application with the goal of making Orca-T available to patients who need it.”

The safety and efficacy of Orca-T have not been determined by any regulatory authority. Orca-T is currently being evaluated under Priority Review by the U.S. Food and Drug Administration (FDA) with a Prescription Drug User Fee Act (PDUFA) target action date of April 6, 2026.

About Precision-T

Precision-T (NCT05316701) is a randomized, open-label multi-center study that evaluated the safety, efficacy and tolerability of Orca Bio’s lead investigational allogeneic T-cell immunotherapy, Orca-T, compared to conventional allogeneic hematopoietic stem cell transplant (alloHSCT). Orca Bio received guidance from the U.S. Food and Drug Administration on the design of Precision-T, which evaluated Orca-T in patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), high-risk myelodysplastic syndrome (MDS) and mixed-phenotype acute leukemia (MPAL). There are 19 leading treatment centers participating in the trial, which enrolled 187 patients across the U.S.

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Joshua Murray

Orca Bio Announces $250M in Aggregate Financing in Preparation for Potential Commercialization

Series F, closed in December 2025, builds on recent financing activity to support launch readiness leading up to the Orca-T ® PDUFA date of April 6, 2026

Funding also enables pipeline advancements including new and expanded clinical programs evaluating Orca-T and Orca-Q® in reduced intensity and nonmyeloablative conditioning settings

MENLO PARK, CA, Jan. 9, 2026 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced the completion of a Series F financing round in December 2025 led by Lightspeed Venture Partners. With $250M in new equity capital from its two most recent financing rounds, along with a 2025 amendment to its Silicon Valley Bank credit facility providing up to $100M in additional liquidity, Orca Bio possesses the financial strength to scale its commercial operations and advance its clinical pipeline.

The proceeds will be used to ensure commercial readiness as the company approaches the April 6, 2026 Prescription Drug User Fee Act (PDUFA) target action date for Orca-T, Orca Bio’s lead investigational allogeneic T-cell immunotherapy. The funding will help strengthen the company’s infrastructure to support future commercial scale, including the addition of East Coast manufacturing capacity to complement its Sacramento, CA operations. The capital will also support the accelerated advancement of Orca Bio’s pipeline across multiple clinical programs designed to expand treatment to more patients in need.

“Our financial position is a powerful validation of Orca-T's transformative potential and reflects our commitment to pioneering a new standard in cell therapy,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “With the resources and infrastructure now in place, we are uniquely positioned to bring our first high-precision therapy to leukemia patients in the U.S. This milestone not only solidifies our anticipated commercial launch but also provides the runway to advance our promising pipeline as we seek to redefine treatment across multiple life-threatening blood cancer and autoimmune diseases.”

In parallel to commercialization efforts, Orca Bio remains focused on advancing its pipeline of high-precision cell therapies. The company progressed two clinical programs designed to evaluate Orca-T and Orca-Q in both the reduced intensity conditioning (RIC) and nonmyeloablative (NMA) settings for patients who may not be candidates to receive a traditional myeloablative conditioning (MAC) regimen.

“While myeloablative conditioning offers the best chance to eradicate disease with a traditional allogeneic stem cell transplant, the high toxicity levels carry significant risks, particularly for older patients or those with co-morbidities,” said Scott McClellan, M.D., Ph.D., chief medical officer at Orca Bio. “Less intensive conditioning regimens are safer for patients who are not candidates for myeloablative conditioning. Through these new studies, we aim to evaluate if Orca-T and Orca-Q can bring safer, curative interventions to a broader population of blood cancer patients.”

SERENE-T Phase 2 Study: SERENE-T (NCT07216443) is a new multicenter, open-label Phase 2 trial evaluating the safety, tolerability and efficacy of Orca-T in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) undergoing RIC or NMA.
Expanded Phase 1b Study of Orca-Q: The first patients have been treated in the expanded Phase 1b study (NCT03802695) which now includes three additional cohorts of patients receiving RIC or NMA with either matched related or unrelated, 7/8 mismatched unrelated or haploidentical related donors. Orca-Q is Orca Bio’s second-generation investigational allogeneic T-cell immunotherapy for patients with AML, MDS or mixed phenotype acute leukemia (MPAL).

Both studies are now enrolling with plans to open at additional centers across the U.S. For more information, visit ClinicalTrials.gov.

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Orca Bio Presents Positive Data Reinforcing Clinical Profile of Orca-T and Orca-Q at 2023 Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR

Three oral presentations showcase clinical evidence for Orca Bio’s promising pipeline of early- and late-stage high-precision cell therapies

Orca-T demonstrated high relapse-free survival in recipients with fully matched donors and early potential in patients with mismatched donors

Orca-Q showed improved graft-versus-host disease-free, relapse-free survival in patients with haploidentical donors

MENLO PARK, CA, February 16, 2023 – 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 data from the company’s investigational high-precision cell therapy programs, Orca-T and Orca-Q, were presented in three oral presentations at the 2023 Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR.

Positive data on Orca-T was presented from the single-center Phase 2 and multi-center Phase 1b trials of patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), myelodysplastic syndromes (MDS) and other hematological malignancies. Outcomes with Orca-T appeared to be further enhanced in patients who received a conditioning regimen of busulfan, fludarabine and thiotepa (BFT). At 12 months, the 71 patients in the Orca-T BFT subgroup reported no non-relapse mortality (0%), and high rates of relapse-free survival (87%), graft-versus-host disease-free, relapse-free survival (GRFS) (81%) and overall survival (94%). These data were previously presented at the 64th American Society of Hematology (ASH) Annual Meeting in December 2022.

In a second oral presentation, new data highlighted how expanding the donor pool may help address disparities in access to transplant. Today, approximately 70% of blood cancer patients do not have access to a fully matched related donor, and the likelihood of a patient finding a matched unrelated donor in the U.S. is as low as 29% for some ethnic backgrounds. While the use of human leukocyte antigen (HLA) mismatched donors has increased access to treatment for these patients undergoing allogeneic hematopoietic stem cell transplant (alloHSCT), clinical outcomes have also been associated with significantly worse overall survival, disease-free survival, treatment-related mortality and acute graft versus host disease (aGvHD). In a small cohort (n=8), Orca-T demonstrated promising results in patients with HLA mismatched (7/8) donors, including no cases of severe GvHD or non-relapse mortality and 100% overall survival to date. While this early data is encouraging, more studies of Orca-T in this patient population are ongoing and will provide additional clinical data in this setting.

"As we continue to enroll patients in our pivotal Phase 3 trial of Orca-T, we are extremely encouraged by its continued potential to improve relapse-free and overall survival rates,” said Ivan Dimov, Ph.D., co-founder and chief executive officer of Orca Bio. “Beyond its promise to enhance outcomes and reduce deadly, transplant-related risks, this early evidence that Orca-T may improve clinical outcomes in patients who can’t find a fully matched donor is an important step toward our ultimate goal of offering a safe and effective treatment to all patients who may benefit.”

Orca Bio also presented findings from a Phase 1 multi-center trial of its second investigational cell therapy, Orca-Q, showing that patients with haploidentical – or half-matched – allogeneic hematopoietic stem cell donors, experienced no moderate-to-severe chronic GvHD (0%) and an improved GRFS rate (75%). Orca-Q is a proprietary composition of enriched CD34+ stem cells combined with specific T cell subsets derived from haploidentical donors. Unlike standard of care haploidentical alloHSCT, Orca-Q does not require post-transplant cyclophosphamide (PTCy). These data were also previously presented at the ASH Annual Meeting.

“A haploidentical stem cell transplant is currently the only curative treatment option available for the majority of blood cancer patients who lack a matched donor, but providers often find themselves balancing the risk of relapse and the risk of debilitating side effects like GvHD, infections and other toxicities,” said Samer Srour, M.D., Department of Stem Cell Transplantation and Cellular Therapy, The University of Texas MD Anderson Cancer Center. “These interim findings show patients treated with Orca-Q experienced improved outcomes with significantly fewer transplant-related toxicities, suggesting this novel cell therapy could help to address this critical unmet medical need.”

Links to the abstracts follow:

Oral Presentation Title: Precision-Engineered Cell Therapy Orca-T Demonstrates High Relapse-Free Survival at 1 Year While Reducing Graft-Versus-Host Disease and Toxicity

Oral Presentation Title: Orca-T, a High-Precision Cell Therapy, for the Treatment of Hematologic Malignancies in Patients with 7/8 Mismatch Donors

Oral Presentation Title: Orca-Q Demonstrates Favorable GvHD-and-Relapse-Free Survival with Haploidentical Donors without Post-Transplant Cyclophosphamide

Poster Presentation Title: Estimating the Current and Future Costs and Health Outcomes of Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation (Allo-HCT)

About Orca-T

Orca-T is an investigational high-precision allogeneic cell therapy consisting of infusions containing regulatory T cells, conventional T cells and CD34+ stem cells derived from peripheral blood from either related or unrelated matched donors. Orca-T has received Regenerative Medicine Advanced Therapy (RMAT) designation from the U.S. Food and Drug Administration and is being studied to treat multiple hematological malignancies.

About Orca-Q

Orca-Q is Orca Bio’s second investigational high-precision allogeneic cell therapy to enter clinical development for hematological malignancies. Orca-Q is a proprietary composition of enriched CD34+ stem cells combined with specific T cell subsets derived from haploidentical donors that are purified through Orca Bio’s high-precision platform. Orca-Q is a therapy that has the potential to improve patient outcomes and reduce the risks of graft versus host disease, without the use of post-transplant cyclophosphamide (PTCy) in patients for whom a full human leukocyte antigen (HLA) match cannot be found.

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 standard allogeneic stem cell transplants, like graft versus host disease and other debilitating transplant-related toxicities. 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 www.orcabio.com and follow Orca Bio on Twitter: @OrcaBio.

Contact:

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Kelsey Grossman

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Joshua Murray

ir@orcabio.com

Orca Bio Presents New Clinical Data on Orca-T® in Older Patients Using Reduced Intensity Conditioning Plus New Analyses from the Precision-T Phase 3 Study at the 67th ASH Annual Meeting

Patients aged 60-75 treated with Orca-T and a reduced intensity conditioning regimen (RIC) experienced low incidence of acute and chronic GvHD with low rates of disease relapse

Results also highlight the encouraging early use of RIC Orca-T in the outpatient setting for the first time

An observational analysis comparing Phase 3 outcomes to PTCy found Orca-T delivered favorable overall survival and lower non-relapse mortality

New Precision-T analyses suggest the benefit of Orca-T extends to older patients and those with higher-risk disease

Patient reported outcomes demonstrate favorable health-related quality of life metrics, fewer ICU stays and lower likelihood of rehospitalizations with Orca-T

MENLO PARK, CA, December 6, 2025 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced new data presented on its lead investigational allogeneic T-cell immunotherapy, Orca-T, at the 67th American Society of Hematology (ASH) Annual Meeting.

Orca-T with Reduced Intensity Conditioning

The new results of a single-center, open-label Phase 1 investigator-sponsored trial evaluating Orca-T in patients aged 60-75 (median 68 years) with a reduced intensity conditioning regimen (RIC) for the treatment of acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), myelodysplastic syndrome (MDS) and myeloproliferative neoplasm (MPN) showed a low incidence of both acute and chronic graft versus host disease (aGvHD, cGvHD) while maintaining a low rate of disease relapse.

“Many older patients with hematological malignancies are not eligible for myeloablative allogeneic stem cell transplant due to the significant toxicities associated with it. A conventional reduced intensity alloHSCT can be safer and more tolerable, but it may also reduce the curative potential,” said Everett Meyer, M.D., Ph.D., hematologist and associate professor of medicine in Blood and Marrow Transplantation and Cellular Therapy at Stanford Health Care. “These early results suggest Orca-T following reduced intensity conditioning may preserve a meaningful graft-versus-leukemia effect while achieving low rates of toxicities, including acute and chronic GvHD. While additional research is needed, these findings support Orca-T as a potentially feasible option for older adults with blood cancer.”

Highlighted in an oral session, patients (n=46) with 8/8 matched donors were conditioned with fludarabine/melphalan/total body irradiation (TBI) (n=11) or fludarabine/thiotepa/TBI (n=12). Conditioning was further reduced where 23 patients were enrolled in a cohort eligible for outpatient treatment. Also included in the analyses was a cohort of patients (n=7) with 7/8 matched donors receiving fludarabine/thiotepa/TBI.

All patients (n=53) had successful neutrophil engraftment at a median of 15 days (range 9-39). At one year, there was no aGvHD grade 3-4 observed, and the rate of aGvHD grade 2 was 12.3% (95% CI, 5-23%). The rate of moderate-to-severe cGvHD was 9.6% (95% CI, 3-21%). At one year, relapse-free survival (RFS) and graft versus host disease relapse-free survival (GRFS) were 82% (95% CI, 72-94%) and 72% (95% CI, 60-87%), respectively. The overall survival (OS) was 88% (95% CI, 79-98%) and non-relapse mortality (NRM) was 10% (95% CI, 4-20%). The outpatient-eligible cohort experienced NRM of 0%, RFS of 80% (95% CI, 65-100%) and OS of 95% (95% CI, 87-100%).

“We are energized by these new data, which reinforce our belief that Orca-T has the potential to expand curative treatment options to many more people living with serious blood cancers, including those who may not be eligible for a myeloablative transplant today, and even patients treated in the outpatient setting,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “Our Serene-T Phase 2 study evaluating Orca-T with RIC recently opened for enrollment and is the next step towards understanding if Orca-T may provide a path to treatment for more patients in need of therapeutic options.”

New Analyses from the Precision-T Phase 3 Study

Retrospective Comparison of Orca-T versus PTCy-Based GvHD Prophylaxis

An observational analysis compared a dataset derived from patients who received Orca-T in the Precision-T Phase 3 study (n=45) to a historical PTCy patient cohort (n=475) derived from the Center for International Blood and Marrow Transplant Research (CIBMTR).

At one year, OS was 94% with Orca-T compared to 81% with PTCy. RFS was 86% and 70% for Orca-T and PTCy, respectively. There was 0% NRM with Orca-T and 9.7% with PTCy, which achieved statistical significance. There was 13.8% relapse in the Orca-T cohort and 21% in the PTCy cohort. The rate of cGvHD was 14.7% with Orca-T versus 8.2% with PTCy. Of note, the OS in patients over the age of 50 was 100% with Orca-T compared to 75% with PTCy.

These outcomes were achieved using only single-agent tacrolimus for pharmacological GvHD prophylaxis for Orca-T recipients, in contrast to the triple-agent regimen used with PTCy, implicating the potential role of immune reconstitution in both disease control and mitigating posttransplant complications.

Orca-T Improved GvHD-free Survival Across Patient Demographics

In subset analyses from the Precision-T Phase 3 study comparing Orca-T to a conventional alloHSCT plus tacrolimus and methotrexate (Tac/MTX), Orca-T demonstrated improved clinical outcomes overall and across subgroups with varied demographic and clinical features. For all patients, the rate of survival free from cGvHD (cGFS) was 78% and 38% for Orca-T and Tac/MTX, respectively. For patients over the age of 50, the rate of cGFS was 74% and 35% for Orca-T and Tac/MTX, respectively. For all patients, the rate of GRFS was 63% and 31% for Orca-T and Tac/MTX respectively, and 59% and 23% for patients over the age of 50 with Orca-T and Tac/MTX, respectively.

Notably, OS and NRM were similar for patients aged 51-65 as in the entire safety population. For patients over the age of 50 at one year, OS was 94% (77%, 98%) for Orca-T patients (n=31) versus 80% (61%, 91%) for Tac/MTX patients (n=32) (HR=0.48 [0.12, 1.89]). Rates of NRM were 6.5% (1.1%, 19%) with Orca-T vs 16% with Tac/MTX (5.7%, 31%) (HR=0.49 [0.11, 2.06]). Together, these data suggest that the results of Orca-T extend to older patients and those with high-risk disease.

Health-Related Quality of Life: Patient Reported Outcomes

An exploratory endpoint from the Precision-T Phase 3 study evaluating health-related quality of life (HRQoL) and hospitalization patterns showed that Orca-T delivered marked improvements over conventional alloHSCT. Patients receiving Orca-T experienced faster recovery to, and higher improvement above, baseline HRQoL, fewer ICU stays, lower likelihood of rehospitalization and higher rehospitalization-free survival, suggesting better early post-treatment recovery and a lower burden of GvHD symptoms.

FACT-BMT total scores were consistently higher for Orca-T recipients across all time points, with Orca-T recipients exceeding baseline scores across physical well-being, functional well-being and transplant-specific subscales by day 100, while the alloHSCT arm did not surpass baseline until day 365. By day 365, Orca-T scores across these domains were higher by a magnitude of two or more compared to the control arm.

“The additional analyses from our Phase 3 study further highlight Orca-T’s potential superiority across critical measures, from lower rehospitalization rates to improved outcomes in older patients,” said Scott McClellan, M.D., chief medical officer at Orca Bio. “These results continue to strengthen our conviction that Orca-T has the potential to transform the transplant experience and meaningfully raise the standard of care for patients and providers.”

About Precision-T

About Orca-T

About Orca Bio

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Orca Bio Announces FDA Acceptance and Priority Review of the Biologics License Application (BLA) for Orca-T® to Treat Hematological Malignancies

FDA assigns PDUFA target action date of April 6, 2026

If approved, Orca-T would be the first allogeneic T-cell immunotherapy for the treatment of hematological malignancies including acute myeloid leukemia, acute lymphoblastic leukemia and myelodysplastic syndromes

MENLO PARK, CA, October 6, 2025 – Orca Bio, a late-stage biotechnology company committed to transforming the lives of patients through high-precision cell therapy, today announced the U.S. Food and Drug Administration (FDA) has accepted for Priority Review the Biologics License Application (BLA) seeking approval for Orca-T, its lead investigational allogeneic T-cell immunotherapy, for the treatment of hematological malignancies including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL) and myelodysplastic syndromes (MDS).

The FDA granted the BLA Priority Review with a Prescription Drug User Fee Act (PDUFA) target action date of April 6, 2026.

"A stem cell transplant has been the only potentially curative option for many people with AML, ALL or MDS, however treatment-related toxicities too often hinder patient recovery. Acceptance of the Orca-T BLA marks a pivotal moment in our ability to deliver a first-in-class therapy designed to improve survival free from complications like graft versus host disease,” said Nate Fernhoff, Ph.D., co-founder and chief executive officer at Orca Bio. “Supported by positive Phase 3 clinical data, today’s regulatory milestone reflects important recognition of the transformative potential of Orca-T. We look forward to working collaboratively with the FDA on the review of our application with the goal of advancing Orca-T and making it available to patients in need.”

The BLA submission for Orca-T is supported by positive results from the pivotal Phase 3 study, Precision-T (NCT04013685), a randomized, open-label multi-center study that evaluated the safety, efficacy and tolerability of Orca-T compared to conventional allogeneic hematopoietic stem cell transplant (alloHSCT) in patients with AML, ALL and MDS. The study met its primary endpoint of a statistically significant improvement in survival free of moderate-to-severe chronic graft versus host disease (cGvHD) with Orca-T versus alloHSCT.

About Orca-T

Orca-T is an investigational allogeneic T-cell immunotherapy being evaluated for the treatment of multiple hematological malignancies including acute leukemias and myelodysplastic syndromes. Orca-T is composed of highly purified regulatory T-cells, hematopoietic stem cells and conventional T-cells derived from peripheral blood from either related or unrelated matched donors. Orca-T has received Regenerative Medicine Advanced Therapy (RMAT) and Orphan Drug Designation for the prevention of graft versus host disease or death in patients eligible for hematopoietic stem cell transplant from the U.S. Food and Drug Administration.

About Orca Bio

Orca Bio is a late-stage biotechnology company developing high-precision cell therapies for the treatment of blood cancer and autoimmune diseases. The company’s manufacturing platform uses single-cell precision to create proprietary, uniquely-defined products designed to replace a patient’s diseased blood and immune system with a healthy one. At Orca Bio, we are on a mission to redefine what’s possible for patients by transforming the field of curative allogeneic cell therapy. For more information, visit www.orcabio.com.

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Orca Bio Presents New Clinical Data on its Pipeline of High-Precision Cell Therapies including Orca-Q® Without GvHD Prophylaxis and Orca-T/CAR-T Combination Therapy at the 67th ASH Annual Meeting

Orca-Q, Orca Bio’s second investigational allogeneic T-cell immunotherapy, showed low rates of acute and chronic GvHD, infections and non-relapse mortality with and without GvHD prophylaxis

Orca-T plus CAR-T combination therapy, OrCAR-T™, showed improved relapse and overall survival rates compared to autologous CAR19/22 treatment in patients with B-ALL

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.”

About Orca-Q

Orca-Q is Orca Bio’s second-generation investigational allogeneic T-cell immunotherapy under evaluation in clinical trials for the treatment of multiple hematologic malignancies, including in patients with haploidentical and mismatched donors. Orca-Q is a proprietary composition of stem cells combined with specific T-cell subsets derived from healthy donors and engineered by Orca Bio’s high-precision platform.

About Orca Bio

Trademarks or registered trademarks used in this press release are the property of their respective owners.

Contact:

Corporate Communications

Kelsey Grossman

Investor Relations

Joshua Murray

ir@orcabio.com