HLA-A*02:01-restricted T-cell receptor program is designed to exploit the hematopoietic-restricted minor histocompatibility antigen HA-2 as a genetically precise target for leukemia and other liquid cancers
Cellantra, an in vivo gene therapy and next-generation immuno-oncology biotechnology company, today announced the discovery and invention of a novel T-cell receptor (TCR) candidate directed against HA-2, a hematopoietic-restricted minor histocompatibility antigen presented by HLA-A*02:01. HA-2 is derived from a naturally occurring polymorphism in MYO1G and has preferential hematopoietic expression.
The proprietary receptor is being developed for TCR-engineered T-cell (TCR-T) applications in hematologic malignancies, including genetically eligible patients with acute myeloid leukemia, myelodysplastic syndromes, acute lymphoblastic leukemia and other blood cancers in the setting of allogeneic hematopoietic cell transplantation. HA-2-specific T-cell recognition has previously demonstrated anti-leukemic activity in experimental and transplant-associated settings.
In the appropriate patient-donor genetic configuration, HA-2 can create a post-transplant immune target that distinguishes residual recipient-derived hematopoietic cells from healthy donor-derived hematopoiesis. Cellantra believes this biology can provide a precision framework for strengthening graft-versus-leukemia activity while seeking to limit recognition of nonhematopoietic tissues.
A New HA-2 TCR Designed for Genetically Precise TCR-T Therapy
Cellantra developed the HA-2 program using its integrated TCR discovery, computational immunology, peptide-HLA modeling and protein-engineering platform. The lead receptor is designed to recognize the HA-2 peptide in the context of HLA-A*02:01 and to activate engineered T cells against HA-2-positive hematopoietic targets.
The candidate has advanced through the company’s discovery and molecular-prioritization stage and is now being evaluated for functional avidity, target-cell recognition, HLA dependence, peptide cross-reactivity, alloreactivity and broader translational safety. Receptor-specific sequence, affinity and performance data remain proprietary pending further validation and intellectual-property development.
The HA-2 TCR-T program is being developed around several core objectives:
- selective recognition of the HA-2 peptide-HLA-A*02:01 complex;
- strong functional activity against HA-2-positive malignant hematopoietic cells at disease-relevant antigen density;
- genotype-defined use in patient-donor pairs intended to preserve healthy donor-derived hematopoiesis after allogeneic HCT;
- systematic screening for unrelated peptide-HLA cross-reactivity, off-target recognition and unintended HLA alloreactivity;
- compatibility with donor-derived TCR-T manufacturing and future engineered-cell control modules; and
- development across multiple hematologic malignancies rather than dependence on a single leukemia-associated surface antigen.
Turning a Transplant Difference Into a Therapeutic Target
Minor histocompatibility antigens arise from inherited protein variants that can differ between a transplant recipient and donor even when major HLA alleles are appropriately matched. Hematopoietic-restricted minor histocompatibility antigens can therefore provide selective targets for residual recipient hematopoiesis following allogeneic HCT.
In a properly selected setting, engineered donor T cells expressing an HA-2-specific TCR may recognize residual recipient-derived leukemia, pre-leukemic clones and other HA-2-positive hematopoietic cells, while newly established donor hematopoiesis lacks the relevant target configuration. This creates a distinct therapeutic model: rather than identifying a tumor-only surface protein, the program uses transplant genetics to create a selective immune differential between diseased recipient hematopoiesis and the donor graft.
“HA-2 gives us a fundamentally different way to think about liquid-tumor targeting,” the company said. “Instead of asking whether leukemia expresses a unique surface marker, we can use a defined peptide-HLA target and the genetics of an allogeneic transplant to create therapeutic selectivity. Our objective is to develop an HA-2 TCR with the functional strength, specificity and safety profile required to deepen graft-versus-leukemia activity without sacrificing the donor hematopoietic system.”
Potential Application Across Liquid Tumors
Because HA-2 is linked to the hematopoietic lineage rather than to a single malignant subtype, Cellantra is evaluating the program as a potential platform TCR-T strategy across genetically eligible hematologic malignancies.
Initial development is expected to emphasize high-risk or relapsed myeloid and lymphoid disease following allogeneic HCT, where prevention or elimination of residual recipient-derived malignant hematopoiesis could have significant therapeutic value. Current clinical development in the field includes HA-2-directed TCR-engineered donor T cells being evaluated after HCT in AML, MDS and ALL.
The company also intends to evaluate whether the receptor can be paired with additional T-cell engineering technologies, including controlled receptor expression, persistence tuning, safety switches and other cell-state programs. Longer-term applications may include integration with targeted gene-delivery technologies, although direct in vivo programming of an HA-2 TCR-T product remains exploratory.
Building Toward Preclinical Validation
Cellantra will next focus on orthogonal experimental confirmation of HA-2/HLA-A*02:01 recognition, killing of HA-2-positive malignant hematopoietic targets, sparing of HA-2-negative controls, cytokine response, antigen-density sensitivity and persistence-related functional characteristics.
A major development priority will be comprehensive specificity testing. Prior HA-2 research has demonstrated that high functional sensitivity alone does not guarantee a clean safety profile: an experimentally studied high-affinity HA-2-reactive TCR showed unintended recognition linked to a cross-reactive human peptide. This makes peptide-library screening and testing against nonhematopoietic cells important components of candidate selection.
Cellantra will therefore prioritize receptor specificity and translational safety alongside functional activity. These studies are intended to determine whether the candidate meets the company’s internal criteria for formal preclinical advancement and for development of a genetically defined patient-donor selection strategy.
The HA-2 TCR-T candidate is investigational and has not been approved for therapeutic use. Clinical safety and efficacy have not been established. Successful application would require appropriate HLA, HA-2 and patient-donor genetic selection, and the program may not be suitable for all patients with hematologic malignancies.
About Cellantra
Cellantra is a biotechnology company developing next-generation in vivo gene therapy and precision immuno-oncology technologies. The company is building a pipeline spanning engineered T-cell receptor programs, intracellular and peptide-HLA cancer targets, in vivo immune-cell programming and advanced nucleic-acid delivery technologies.
Cellantra’s research strategy combines computational molecular design, target discovery, protein engineering, targeted delivery and experimental validation with the long-term objective of transforming complex biological discoveries into programmable therapeutic modalities.
Cellantra – Make the World a Better Place.
Forward-Looking Statements
This press release contains forward-looking statements about Cellantras HA-2 TCR-T program. Discovery-stage findings may not predict clinical outcomes. TCR-T therapies may involve HLA restriction, graft complications, unintended alloreactivity and peptide cross-reactivity. The program is investigational and has not been demonstrated to be safe or effective in humans.
