Percheron Therapeutics Ltd (ASX:PER, OTC:PERCF) has welcomed new preclinical data published in Cell Reports, demonstrating that its investigational antibody HMBD-002 enhances the effects of radiotherapy in squamous cell carcinoma of the head and neck (SCCHN).
Conducted by a team at Stanford University under the leadership of Professor Quynh-Thu Le, the study showed that combining HMBD-002 with radiotherapy significantly prolonged survival in mouse models. These findings underscore the potential of targeting VISTA, HMBD-002’s molecular target, to overcome resistance mechanisms and improve treatment outcomes.
“This is very encouraging data,” Percheron CEO Dr James Garner said. “Radiotherapy is a critical therapeutic tool in the treatment of many cancers and is very widely used, but its efficacy is often suboptimal, and recurrence is common. These data suggest that addition of a VISTA inhibitor such as HMBD-002 could significantly potentiate the effect of radiotherapy, leading to better outcomes for patients.”
SCCHN: A major cancer target with limited therapeutic options
Squamous cell carcinoma of the head and neck is a group of malignancies affecting the mouth, throat, larynx, and neck, comprising approximately 4% of all cancers in the United States. With an estimated 70,000 new cases annually, SCCHN presents a significant therapeutic challenge. Radiotherapy is a cornerstone of current treatment, yet resistance and recurrence remain prevalent.
Stanford’s preclinical work revealed that radiotherapy induces upregulation of VISTA, a suppressor of immune activity, on both tumour and immune cells.
This VISTA expression is believed to dampen the immune system’s ability to clear irradiated cancer cells, suggesting a mechanism of resistance that can potentially be reversed.
HMBD-002 enhances immune response to radiotherapy
By inhibiting VISTA, HMBD-002 appears to reprogram the immune microenvironment into a pro-inflammatory, anti-tumour state.
In the MOC2 model of SCCHN, the combination of radiotherapy with HMBD-002 extended median survival to 35.5 days, compared to 27 days with radiotherapy alone — a statistically significant improvement (p < 0.05).
This immune modulation was less pronounced in melanoma and breast cancer models, likely due to the higher inherent sensitivity of those tumours to radiotherapy. Nonetheless, the enhancement seen across multiple models points to HMBD-002’s potential utility in a range of solid tumours.
Previous attempts to combine radiotherapy with checkpoint inhibitors targeting PD-1 have generally yielded disappointing results. The Stanford study suggests that VISTA may be a more effective target in this context, offering a novel approach to enhancing radiotherapy response.
Preclinical validation and implications for future trials
The findings stem from rigorous preclinical testing using patient-derived xenograft (PDX) models, in which human tumours are grafted onto mice. The experiments demonstrated tumour suppression and improved survival, validating HMBD-002’s mechanism of action and supporting its advancement.
While mouse models are not fully predictive of human responses, they provide critical guidance for prioritising therapeutic strategies. The promising results justify further investigation of HMBD-002 in clinical settings — especially in combination with radiotherapy across indications such as SCCHN, lung cancer, breast cancer and melanoma.
About Percheron Therapeutics
Percheron is focused on oncology and rare diseases.
Its lead asset, HMBD-002, is a first-in-class anti-VISTA monoclonal antibody that has completed a Phase I trial demonstrating a favourable safety profile.
Percheron intends to initiate further clinical trials in calendar year 2026.