AdAlta (ASX:1AD) has reported a series of positive clinical results that could reshape expectations for treating advanced mesothelioma, a disease where patients typically face limited options and poor outcomes.
In new data from ongoing investigator-initiated trials in China, the company’s experimental CAR-T therapy, BZDS1901, demonstrated tumour shrinkage and even complete clearance in a subset of heavily pretreated patients.
The update covers 14 patients with advanced mesothelioma who had either failed or relapsed after chemotherapy or immunotherapy. Historically, only a small proportion of such patients respond meaningfully to existing second-line treatments, with response rates ranging from 11 to 29 per cent and median survival often under nine months. Against that backdrop, the emerging data for BZDS1901 stands out.
At the highest dose levels tested, half of the patients experienced tumour shrinkage of more than 30 per cent, translating to an overall response rate of 50 per cent. Notably, two patients had their tumours disappear entirely on imaging scans, a rare outcome in this setting. In one case, tumours measuring 5 centimetres prior to treatment became undetectable within 3 months and have remained so for more than a year.
More than a quarter of patients have shown ongoing tumour shrinkage over several months, suggesting that the engineered CAR-T cells remain active in the body. Survival trends are also encouraging, with several patients living beyond twelve months and others still being monitored as they approach that milestone.
Updated safety protocols have enabled the use of higher doses without dose-limiting toxicities, and no cases of severe cytokine release syndrome have been observed. While one serious neurological event occurred, it resolved quickly and the patient went on to achieve a complete response, underscoring both the risks and potential rewards of the approach.
The therapy itself targets mesothelin, a protein commonly found in aggressive cancers, including mesothelioma, certain lung cancers and some gynaecological tumours. The current Generation 2 version of BZDS1901 has been engineered to be faster and cheaper to manufacture, requiring less than two days and lower cell doses than earlier iterations, while still delivering comparable or improved efficacy signals.
The company said it is now planning additional expansion cohorts and studies, with the goal of advancing BZDS1901 into broader clinical development.
AdAlta CEO and Managing Director Tim Oldham framed the update as a meaningful step forward, saying, “These latest results further strengthen our confidence in BZDS1901’s potential to make a real difference for patients with advanced mesothelioma. We remain focused on progressing this program so that Australian patients can be the first outside China to access this promising new therapy.”