Novel Evobody Bispecific Antibodies Show Promise in Ovarian Cancer by Targeting Vγ9Vδ2 T Cells
Key Insights
Researchers developed Evobodies (search), first-in-class bispecific antibodies that selectively activate BTN3A (search) on FOLR1 (search)-positive tumor cells to trigger Vγ9Vδ2 T cell responses specifically at tumor sites.
The lead candidate ETA-067 (search) demonstrated potent tumor cell elimination with ~200-fold proliferation of Vγ9Vδ2 T cells while avoiding cytokine release syndrome and premature immune cell exhaustion.
In patient-derived ovarian tumor models, ETA-067 (search) achieved 70-90% tumor cell lysis at very low effector-to-target ratios and successfully expanded tumor-infiltrating lymphocytes without upregulating exhaustion markers.
Scientists have developed a novel class of bispecific antibodies called Evobodies (search) that harness the natural anti-infection biology of gamma-delta T cells to combat ovarian cancer (search). The innovative approach selectively activates immune responses at tumor sites while avoiding the systemic toxicities associated with conventional T cell engagers.
Targeting the Infection Response Pathway
Evobodies (search) work by mimicking bacterial infections specifically on tumor cells through selective activation of BTN3A (search) (CD277 (search)), a membrane protein that normally detects phosphoantigens from metabolically active bacteria. The bispecific design combines a low-affinity BTN3A-binding domain with high-affinity binding to folate receptor alpha (search) (FOLR1 (search)), which is expressed in approximately 80% of epithelial ovarian cancer (search) cases but nearly absent in normal tissues.
"BTN3A (search) is an integral plasma membrane protein that functions in inside-out signaling as an omnipresent infection sensor, expressed on every cell of our body," the researchers explained. By restricting BTN3A activation to FOLR1 (search)-positive cells, Evobodies (search) create a tumor-specific "kill me" signal that triggers localized immune responses.
Superior Therapeutic Window
The lead candidate ETA-067 (search) demonstrated remarkable selectivity in preclinical studies. Through germline reset engineering to reduce BTN3A (search) affinity, researchers achieved over 1000-fold higher potency against FOLR1 (search)-positive cells compared to FOLR1-knockout cells. Surface plasmon resonance measurements confirmed a four-fold decrease in BTN3A binding affinity compared to the parental antibody, enabling tumor-restricted activation.
In Real-Time Cell Analysis assays, ETA-067 (search) induced potent cytotoxicity against OVCAR-3 ovarian cancer (search) cells while showing minimal activity against FOLR1 (search)-negative variants, establishing a substantial therapeutic window for clinical development.
Localized Immune Activation Without Systemic Toxicity
A key advantage of Evobodies (search) is their ability to create cytokine gradients that peak at tumor sites while sparing peripheral blood cells. In comparative studies, ETA-067 (search) induced significant IFN-γ and TNF-α release when pre-expanded Vγ9Vδ2 T cells were co-cultured with tumor cells, but produced no cytokine release when added to peripheral blood mononuclear cells alone.
This contrasts sharply with conventional CD3 bispecific antibodies, which caused tumor-independent cytokine production in peripheral blood samples. The selective activation pattern suggests Evobodies (search) may circumvent cytokine release syndrome, a major dose-limiting toxicity of current T cell engagers.
Robust Immune Cell Proliferation
Evobodies (search) demonstrated exceptional ability to expand Vγ9Vδ2 T cells, addressing their typically low abundance in tumors. In 13-day proliferation assays, ETA-067 (search) induced approximately 200-fold expansion of Vγ9Vδ2 T cells at 10 nM concentration and 100-fold expansion at 1 nM, while control cultures showed no proliferation.
Importantly, degranulation assays confirmed that ETA-067 (search) did not cause premature activation or fratricide among immune effector cells, unlike the phosphoantigen BrHPP which induced widespread BTN3A (search) activation and immune cell death.
Patient-Derived Validation
The therapeutic potential was validated using a novel patient-derived ex vivo tumor tissue model (exTuTiMo) that maintains the intact immunosuppressive tumor microenvironment. In freshly isolated ovarian tumor samples, ETA-067 (search) achieved 70-90% tumor cell lysis despite extremely low effector-to-target ratios of 1:240, reflecting physiological conditions.
Analysis of patient tumor tissue revealed 24% pan-cytokeratin-positive tumor cells expressing both FOLR1 (search) and BTN3A (search), with 49% CD45-positive leukocytes. After 10 days of ETA-067 (search) treatment, researchers observed five-fold expansion of Vγ9Vδ2 tumor-infiltrating lymphocytes with a central memory phenotype and minimal expression of exhaustion markers PD-1 and TIGIT.
Clinical Development Pathway
The research addresses a significant unmet need in ovarian cancer (search), where first-line platinum-based chemotherapy achieves 80% response rates but recurrence remains a major challenge. Current FOLR1 (search)-targeting approaches include the recently approved antibody-drug conjugate Mirvetuximab soravtansine-gynx, though efficacy varies substantially depending on disease status.
Evobodies (search) represent a fundamentally different approach by activating the target cell rather than the effector cell, potentially overcoming limitations of conventional bispecific antibodies including immune exhaustion and off-target toxicities. The technology platform could potentially be adapted to other tumor-associated antigens beyond FOLR1 (search).
The researchers concluded that Evobodies (search) offer "promising long-term efficacy in tumor antigen-positive patients" based on their ability to promote Vγ9Vδ2 T cell proliferation, prevent immune cell exhaustion, and eliminate tumors at physiologically relevant effector-to-target ratios.