- Design
- Post hoc analysis of two phase 3 trials' experimental arms
- Population
- 1,142 men with metastatic hormone-sensitive prostate cancer
- Primary outcome
- Overall survival by testosterone breakthrough >35 ng/dL
- Effect
- LATITUDE HR 1.49 (1.07 to 2.08); ARASENS HR 1.18 (0.85 to 1.62)
This post hoc analysis looked at men in the treatment arms of two phase 3 trials for metastatic hormone-sensitive prostate cancer: abiraterone with ADT (LATITUDE, 564 men) and darolutamide with ADT and docetaxel (ARASENS, 578 men). It asked whether testosterone rising above 35 ng/dL during treatment predicted worse outcomes.
In LATITUDE, breakthrough was associated with worse overall survival (HR 1.49, 95% CI 1.07 to 2.08). In ARASENS, the associations with survival (HR 1.18) and progression to castration resistance were not significant.
The authors are clear the findings are exploratory. They do not show that breakthrough causes worse outcomes or establish a testosterone target. But they support measuring testosterone during treatment rather than assuming castration is maintained.
- Check testosterone periodically during ADT-based combination therapy
- Review ADT timing and adherence when testosterone is above castrate level
- Do not change systemic therapy on a single raised testosterone result
- Record testosterone alongside PSA in follow-up notes
Why it matters
Castration is often assumed rather than measured once combination therapy starts.
Don't overread it
Exploratory post hoc analysis; it does not establish causation or a target testosterone level.
The statistics, in plain English
An HR of 1.49 means about 50% higher risk of death over time, but only in LATITUDE. In ARASENS the interval crossed 1.0, so no clear link was seen there.
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