Percheron Therapeutics Ltd (ASX:PER, OTC:PERCF) has unveiled new preclinical data suggesting its lead cancer therapy HMBD-002 could help address treatment resistance in triple-negative breast cancer (TNBC), one of the most aggressive and difficult-to-treat forms of the disease.
The findings were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago and stem from a research collaboration with Brisbane-based QIMR Berghofer Medical Research Institute led by Professor Sudha Rao.
Research points to role for VISTA in treatment resistance
The study focused on VISTA, the immune checkpoint protein targeted by HMBD-002, and its potential role in TNBC.
Researchers used advanced spatial multiomics techniques to analyse tumour samples and datasets from multiple patient cohorts, including 83 patients previously treated with Roche's PD-L1 inhibitor Tecentriq (atezolizumab).
According to the data, VISTA expression increased in patients whose disease became resistant to chemotherapy, suggesting the protein may form part of a mechanism that allows tumours to evade treatment. Researchers also observed elevated VISTA expression following treatment with PD-1 and PD-L1 immunotherapies, indicating the pathway could contribute to resistance against existing immune checkpoint inhibitors.
The authors concluded that the findings "support VISTA as a promising therapeutic target in TNBC". The accompanying ASCO poster noted that VISTA was associated with T-cell exhaustion, recurrence and metastasis, while increased expression after PD-1 and PD-L1 therapy suggested the protein may drive resistance to immunotherapy.
Percheron chief executive officer Dr James Garner said the project represented the most comprehensive effort to date to understand VISTA's role in TNBC.
"Despite huge progress in the treatment of breast cancer over recent decades, there continues to be significant unmet medical need in the disease, and TNBC remains especially challenging," he said.
"This work indicates that VISTA, the molecular target of Percheron's HMBD-002, may play an important role in treatment resistance."
Supports next phase of HMBD-002 development
Triple-negative breast cancer accounts for around 15% of new breast cancer diagnoses and lacks the oestrogen, progesterone and HER2 receptors targeted by many established therapies. While PD-1 and PD-L1 immunotherapies such as Keytruda are approved for the disease, response rates remain limited and researchers continue to seek new treatment approaches.
HMBD-002 is a monoclonal antibody designed to target VISTA, an immune checkpoint regulator involved in suppressing anti-tumour immune responses. Percheron previously reported phase I data showing the drug was generally safe and well tolerated in patients with advanced cancers.
The company said the QIMR team now intends to prepare a peer-reviewed manuscript detailing the findings and additional preclinical data. Percheron is also planning to commence a new clinical trial of HMBD-002 during the second half of calendar 2026.
The ASCO presentation follows a series of recent milestones for the program, including the adoption of the proposed International Nonproprietary Name (INN) "vistermimab" by the World Health Organization and preparations for the next stage of clinical development.