For high-risk, PTEN-deficient metastatic prostate cancer, a proposed strategy to maximize benefit while minimizing toxicity is sequential intensification. Clinicians can administer a triplet of ADT, an ARPI, and docetaxel first, and only after the chemotherapy course is complete, add the AKT inhibitor capivasertib to avoid severe, overlapping toxicities.

The CAPITELLO-281 trial showed the AKT inhibitor capivasertib delayed disease progression in PTEN-deficient prostate cancer. However, without a demonstrated overall survival benefit yet, its path to becoming a new standard of care is uncertain. This highlights the growing debate over whether delaying progression is a sufficient endpoint to justify added toxicities when survival isn't improved.

The CAPItello-281 trial shows the benefit of the AKT inhibitor capivasertib is on a spectrum. Patients with 100% PTEN protein loss by IHC derive a much greater benefit than those with partial loss, suggesting a quantitative biomarker may optimize patient selection.

Because PTEN loss is an early, truncal mutation in prostate cancer, clinicians should perform NGS testing on the first day a patient is seen. This proactive approach ensures that crucial biomarker information is not lost and is available to guide future treatment decisions, such as the use of an AKT inhibitor, should the disease progress.

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.

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 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.

In patients with PTEN loss, cancer growth is driven by the PI3K-AKT pathway, which doesn't activate the PSA gene. This can lead to significant disease progression with a low or stable PSA, making PSA a poor surrogate for disease activity in this sub-population.

The CAPItello-281 trial showed that the clinical benefit of adding the AKT inhibitor capivasertib is directly proportional to the degree of PTEN loss. The greatest separation in survival curves was seen in patients with 99-100% PTEN loss by IHC, suggesting the current trial entry cutoff of >90% may be too broad for optimal patient selection.