Roche gains FDA nod for first PTEN companion diagnostic

Roche has received FDA approval for the VENTANA PTEN (SP218) RxDx Assay, making it the first immunohistochemistry companion diagnostic cleared in the United States to detect PTEN protein loss in prostate adenocarcinoma. Patients identified as PTEN-deficient by the test may now be eligible for treatment with AstraZeneca's capivasertib (TRUQAP) in combination with abiraterone acetate.

The approval, announced on 12 June 2026, is based on data from the CAPItello-281 Phase III trial, which used the assay as its enrolment test. Patients in that study whose tumours showed PTEN deficiency, defined as at least 90% of viable malignant cells lacking cytoplasmic PTEN staining, and who received capivasertib plus abiraterone experienced a statistically significant and clinically meaningful reduction in disease progression compared with the control arm. Full results were published in the Annals of Oncology in January 2026.

Clinical significance

PTEN is a tumour suppressor protein, and its loss is among the more common genomic alterations observed across multiple cancer types. In prostate cancer specifically, PTEN deficiency is associated with faster disease progression and reduced benefit from standard androgen-pathway treatments. Approximately 25% of patients with metastatic hormone-sensitive prostate cancer carry PTEN-deficient tumours on IHC assessment, a meaningful patient fraction given that median survival after a new metastatic prostate cancer diagnosis is estimated at five to six years.

Matt Sause, chief executive of Roche Diagnostics, said the approval would "provide clinicians with a vital tool to identify patients with PTEN loss and potentially provide new therapeutic options." Foundation Medicine, an independent affiliate of the Roche Group, is among the laboratories deploying the kit commercially.

The assay runs on Roche's BenchMark ULTRA instrument using the OptiView DAB IHC Detection Kit, meaning it integrates into pathology workflows already familiar to many hospital laboratories rather than requiring bespoke infrastructure.

Market context

The companion diagnostics sector has grown substantially as targeted therapies move into earlier treatment lines, increasing the commercial premium on validated patient-selection tools. Roche has been one of the most active players in the space, with a broad portfolio of PD-L1, HER2, and other IHC-based assays. Approval of the VENTANA PTEN test extends that franchise into the androgen-pathway modulation segment of prostate oncology, a space that has attracted considerable therapeutic investment from AstraZeneca, Johnson and Johnson, and Pfizer, among others.

For AstraZeneca, the companion diagnostic approval is commercially significant: capivasertib's label in this indication is gated on PTEN-loss status, meaning uptake of the therapeutic is directly dependent on the availability of a validated assay. That alignment of diagnostic and therapeutic approval simultaneously removes a key adoption barrier and creates a durable co-dependency between the two franchises.

Roche's next disclosable milestones in this programme are likely to involve post-market clinical follow-up requirements from the FDA and potential label expansions to reflect additional capivasertib indications as they emerge from AstraZeneca's broader clinical pipeline.