Novartis said on Sunday that initial clinical data for its experimental actinium-based therapy demonstrated signs of anti-tumour activity in prostate cancer patients, including among those who had been treated previously with the company’s own radioligand, Pluvicto.
The findings come from a study that enrolled 101 patients. Among the subgroup that had already received Pluvicto, 52.5% experienced a decline in prostate-specific antigen, or PSA, of at least 50% following treatment with the actinium-based agent. PSA is commonly used as a biomarker for prostate cancer activity.
Response rates were higher among patients without prior exposure to Pluvicto. Data presented at the American Society of Clinical Oncology meeting in Chicago showed that more than 85% of patients with no prior radioligand treatment had PSA levels fall by half, while 58.8% of patients who had received chemotherapy first achieved the same magnitude of PSA reduction.
Novartis’ Chief Medical Officer Shreeram Aradhye emphasized that these are early data and that larger trials will be required to more fully characterize safety, including the severity and the reversibility of side effects—an important consideration if the drug is to be deployed in earlier lines of therapy.
The company is increasing its focus on radioligand therapies that deliver radiation directly to cancer cells and is progressing two late-stage studies of the actinium-based candidate. Radioligand programs now represent nearly 40% of Novartis’ oncology research and development spending, according to the company.
Novartis already markets two radiopharmaceuticals, Pluvicto and Lutathera, which together generated $2.8 billion in sales last year. The broader field of radiopharmaceutical oncology has attracted attention from multiple large drugmakers; the development area has prompted acquisitions by other firms named in the company’s commentary.
Context and next steps
The dataset reflects early-stage clinical activity in a 101-patient cohort and was formally presented at a major oncology meeting. Novartis is advancing the program into two late-stage studies to better define clinical benefit and safety profiles across treatment settings.
What remains unresolved
- The long-term extent and reversibility of adverse events tied to the actinium-based agent remain to be defined in larger populations.
- How efficacy varies across prior-treatment subgroups will require confirmation in expanded trials.
- Regulatory assessment and potential positioning of the drug in earlier lines of therapy will depend on results from upcoming late-stage studies.