Bavdegalutamide Shows Promise Against Prostate Cancer With Specific Mutations
An experimental drug cut PSA levels by at least half in 60% of men with specific prostate tumor mutations, but larger trials must confirm benefit.
Summary
An experimental drug called bavdegalutamide showed its strongest activity in men whose advanced prostate cancers carried specific mutations. The drug helps destroy a protein that tumors use to respond to male hormones. Researchers tested it in men whose cancer resisted testosterone suppression and who had already received another hormone-targeting treatment. Among 20 men with T878 or H875 mutations, 60% saw their prostate-specific antigen, or PSA, levels drop by at least half. Their median time without cancer progression on imaging or death was 11.1 months. Responses were much less common in other tumor groups. Serious treatment-related side effects occurred in 17.4% of participants in the second phase, and 11.1% stopped treatment because of side effects. These preliminary results support further testing, but do not establish longer survival or superiority over existing treatments.
Detailed Summary
Advanced prostate cancer can continue growing despite treatments that suppress male hormones. Bavdegalutamide takes a different approach by helping cells destroy the androgen receptor, a protein that can drive tumor growth. This early human study suggests that specific tumor mutations may identify men most likely to benefit from this strategy.
The phase I/II trial enrolled adult men with metastatic prostate cancer that had progressed despite testosterone suppression, after prior treatment with an androgen receptor pathway inhibitor. Dose escalation in 95 men established 420 milligrams once daily as the recommended dose. Phase II included 144 men and evaluated activity across molecularly defined groups and a group with less previous treatment.
Among 20 men whose tumors carried T878 or H875 androgen receptor mutations, 60% had prostate-specific antigen, or PSA, levels fall by at least half. Median time without imaging evidence of progression or death was 11.1 months. Comparable PSA responses occurred in only 4.3% and 3.1% of two other molecular groups, whose corresponding median times were 4.2 and 5.1 months.
In the less previously treated group, 21.4% achieved that PSA reduction, with median progression-free survival of 11.1 months. Grade 3 treatment-related side effects occurred in 17.4% of phase II participants; none had grade 4 or higher events. Side effects prompted dose reductions in 11.8% and treatment discontinuation in 11.1%. These findings support further testing of mutation-guided treatment rather than assuming all resistant prostate cancers respond similarly.
However, the abstract does not describe a randomized comparison with standard treatment, and the strongest response signal came from a small subgroup. PSA reductions do not establish longer survival or better quality of life. Differences between groups cannot prove comparative benefit. This summary uses the abstract only; full methods, follow-up details, and statistical uncertainty were unavailable. Bavdegalutamide remains an investigational option requiring confirmation in larger trials.
Key Findings
- Among 20 men with AR T878/H875 tumor mutations, 60% achieved a PSA decline of at least 50%.
- Median radiographic progression-free survival was 11.1 months in the T878/H875 group, versus 4.2 and 5.1 months in other molecular groups.
- Less-pretreated men had a 21.4% PSA50 response rate and median radiographic progression-free survival of 11.1 months.
- Grade 3 treatment-related adverse events affected 17.4%; side effects led to treatment discontinuation in 11.1%.
- Tumor mutation profiling may help guide future trials; these results do not establish a survival benefit or justify routine use.
Methodology
This phase I/II study enrolled adult men with metastatic castration-resistant prostate cancer previously treated with an androgen receptor pathway inhibitor. Phase I dose escalation included 95 men and selected 420 mg daily; phase II included 144 men receiving treatment in 28-day cycles. Researchers assessed PSA responses and radiographic progression-free survival across molecular subgroups and a less-pretreated subgroup; the abstract does not describe a randomized comparator.
Study Limitations
This summary is based on the abstract only; detailed methods, follow-up, confidence intervals, and full safety information were unavailable. The strongest response signal involved only 20 men, and no randomized comparator is described, limiting conclusions about comparative effectiveness. PSA declines and radiographic progression-free survival do not establish improved overall survival or quality of life.
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