SHERIDAN, WYOMING -- June 15, 2026 -- Roche has received FDA approval for the VENTANA PTEN (SP218) RxDx Assay, the first immunohistochemistry companion diagnostic cleared to assess PTEN protein loss in patients with prostate adenocarcinoma. The assay identifies patients whose tumours exhibit PTEN deficiency, making them potentially eligible for treatment with AstraZeneca's TRUQAP in combination with abiraterone acetate. Approval is based on results from the CAPItello-281 clinical study, where the assay served as the enrollment diagnostic to identify patients with PTEN-deficient tumours.
PTEN Loss Biology Creates a Clinically Distinct Patient Subgroup
PTEN is a tumour suppressor protein. Its loss is observed across a range of cancer types, and in prostate cancer specifically it is associated with faster disease progression and reduced benefit from current standard-of-care treatments. About 25% of patients with metastatic hormone-sensitive prostate cancer carry PTEN-deficient tumours as evaluated by immunohistochemistry — a substantial proportion of a patient population for which targeted treatment options were previously unavailable.
The VENTANA PTEN (SP218) RxDx Assay addresses that gap directly. It gives clinicians a standardised, FDA-cleared method to determine PTEN protein loss status from tumour tissue, using an immunohistochemical staining process on a BenchMark ULTRA instrument with the OptiView DAB IHC Detection Kit.
Assay Defines Eligibility for TRUQAP Combination Therapy
The clinical cutoff for PTEN protein loss status is defined as 90% or more of viable malignant cells showing no specific cytoplasmic staining. A pathologist's observation of absent or present PTEN expression within the prostate adenocarcinoma tissue determines the result. Patients who meet that threshold may be eligible for TRUQAP in combination with abiraterone acetate, in line with the approved therapeutic product labelling.
In the CAPItello-281 study, patients who received combination therapy with TRUQAP experienced a statistically significant and clinically meaningful reduction in disease progression. That outcome formed the evidentiary basis for the companion diagnostic approval, linking the assay's classification performance directly to a treatment benefit in the defined population.
Metastatic Hormone-Sensitive Prostate Cancer Carries a Serious Prognosis
Prostate cancer is among the leading cancer diagnoses for men in the United States. The metastatic hormone-sensitive form is an aggressive disease state: the average survival following a new metastatic prostate cancer diagnosis is approximately five to six years. For the subset of these patients whose tumours show PTEN deficiency, treatments specifically targeting that biology had not been available before TRUQAP's approval.
Matt Sause, CEO of Roche Diagnostics, addressed the clinical significance of the new assay: "Prostate cancer is one of the leading cancer diagnoses for men in the United States. The FDA approval of our new companion diagnostic will provide clinicians with a vital tool to identify patients with PTEN loss and potentially provide new therapeutic options."
Foundation Medicine Among Early Adopters Running the Assay
Foundation Medicine, an independent affiliate of the Roche Group, is one laboratory already using the VENTANA PTEN (SP218) RxDx Assay companion diagnostic kit to help healthcare providers identify patients with PTEN protein loss. That early deployment within the Roche ecosystem positions the assay for relatively rapid uptake in clinical practice, with an established laboratory infrastructure already in place for processing.
The companion diagnostic model — where a diagnostic test and a therapeutic are developed in clinical alignment — means the assay's clinical utility is tightly bound to TRUQAP's approved indication. Clinicians ordering the test do so specifically to assess treatment eligibility, not as a general prognostic screen.
Approval Reinforces Roche's Companion Diagnostics Strategy
Roche frames this FDA approval within its broader commitment to personalised healthcare and companion diagnostics leadership. The VENTANA platform is an established vehicle for that strategy: the VENTANA MMR RxDx Panel, for instance, is referenced in Roche's separate Tecentriq filing for colon cancer as the immunohistochemistry test used to determine dMMR status.
Companion diagnostics occupy a critical role in oncology's shift toward biomarker-defined treatment pathways. Each approval adds a validated link between a patient's tumour biology and a specific therapeutic option — narrowing the population that receives a given treatment while increasing the probability that those who do receive it will benefit. The VENTANA PTEN (SP218) RxDx Assay follows that same logic for the PTEN-deficient prostate cancer population.
For more information on Roche's diagnostics portfolio and the VENTANA PTEN (SP218) RxDx Assay, visit Roche.