The FDA's critique of both CREST and Potomac trials highlights that while event-free survival (EFS) endpoints were met, the lack of improvement in overall survival or prevention of muscle-invasive disease makes the risk/benefit profile questionable for an early-stage cancer, where treatment-related harm is a primary concern.

In the CAPITELLO-281 trial, PTEN-deficient patients receiving standard-of-care abiraterone had a median time to progression of about two years. This is shorter than expected for the general population, prospectively validating PTEN deficiency as a biomarker for a more aggressive disease phenotype with poor outcomes.

The AKT pathway, activated by PTEN loss, drives cancer growth independently of the androgen receptor, which controls PSA production. This discordance means clinicians cannot rely on PSA alone and must use systematic imaging to detect progression in this specific patient subgroup.

Data from the CAPItello trial showed a significant number of patients with PTEN deficiency experienced radiological progression without a corresponding PSA increase. This challenges the standard reliance on PSA for monitoring in high-risk prostate cancer and suggests a need for more frequent, personalized imaging protocols to detect progression earlier.

Despite some positive clinical trial data for AKT inhibitors in prostate cancer, expert opinion suggests this class of drugs is unlikely to see the light of day in routine clinical practice. Skepticism remains about their overall impact, with a feeling that they do not represent a new, meaningful chapter for treatment.

Using capivasertib in the hormone-sensitive setting is preferred because the cancer is more likely dependent on the AKT pathway for growth. In later, castration-resistant stages, additional genetic alterations can emerge, creating redundant growth signals and potentially diminishing the inhibitor's efficacy.

The EMBARK trial demonstrated an overall survival (OS) benefit, yet experts argue this doesn't automatically make treatment mandatory. For asymptomatic patients with a long life expectancy, factors like treatment-free survival and quality of life are critical considerations, challenging the primacy of OS as the sole decision-driver in this population.

The panel suggests AKT inhibitor trials in prostate cancer have been disappointing due to suboptimal biomarker selection (e.g., PTEN IHC). A similar drug in breast cancer showed significant survival benefit when using a more precise NGS-based strategy, indicating a potential path forward if the right patient population is identified genetically.

Exploratory analysis shows that while patients with 100% PTEN loss have a much worse natural history than those with 90% loss, the therapeutic effect of capivasertib is stable across this spectrum. The drug effectively targets the pathway regardless of the magnitude of loss, making it a robust option for this entire subgroup.