Roche Gains FDA Approval for VENTANA PTEN Companion Diagnostic in Prostate Cancer

Parallel approval pathways for therapeutics and companion diagnostics are now a live regulatory reality: Roche's VENTANA PTEN (SP218) RxDx Assay has received FDA approval as the first immunohistochemistry companion diagnostic cleared to assess PTEN protein loss in prostate adenocarcinoma, directly enabling patient selection for AstraZeneca's capivasertib (TRUQAP) in combination with abiraterone acetate.

The assay is a qualitative IHC test run on Roche's BenchMark ULTRA instrument using the OptiView DAB IHC Detection Kit. Its clinical cutoff is defined as PTEN protein loss in ≥ 90% of viable malignant cells with absent cytoplasmic staining, a threshold established through the CAPItello-281 clinical study, where the assay served as the enrollment diagnostic. Approximately 25% of patients with metastatic hormone-sensitive prostate cancer carry PTEN-deficient tumours by IHC, defining the eligible population this CDx is designed to stratify.

For QA and regulatory affairs teams managing co-development programs, the approval illustrates the operational complexity of synchronised CDx and therapeutic submissions. The assay's indication is tightly coupled to the TRUQAP label: eligibility language in the CDx approval references the approved therapeutic product labeling directly, meaning any future label variation on the therapeutic side carries downstream implications for the diagnostic's intended use. Regulatory leads should note that the CAPItello-281 enrollment assay data formed the evidentiary basis for approval, reinforcing ICH Q10-aligned lifecycle thinking across both the diagnostic and drug development programs.

Foundation Medicine, an independent affiliate of the Roche Group, is among the laboratories deploying the VENTANA PTEN (SP218) RxDx Assay kit, signalling that the CDx infrastructure extends beyond Roche's own network. For manufacturers building CDx co-development strategies, the distribution of assay kits to independent laboratory affiliates introduces additional quality system touchpoints that QA directors will need to map against 21 CFR Part 211 and applicable IVD regulations.

The approval positions PTEN-deficient metastatic androgen pathway modulation-naïve or sensitive prostate cancer as a molecularly defined indication with a validated IHC-based patient selection tool, a model that regulatory affairs leads in oncology will likely reference when structuring future CDx submissions under the FDA's companion diagnostic framework.

Source: GlobeNewswire via Roche press release, 12 June 2026.