Clinical and Transcriptomic Characterization of Metastatic Hormone-Sensitive Prostate Cancer Patients with Low PTEN Expression.

Alterations in the PTEN tumor suppressor gene are common in prostate cancer. They have been associated with a more aggressive disease and poor outcomes and potential benefit of targeted therapies. The purpose of this work is to study the clinical and transcriptional landscapes associated to low PTEN mRNA expression in metastatic hormone-sensitive prostate cancer (mHSPC) patients. A multicenter biomarker ambispective study was performed in mHSPC patients. PTEN mRNA expression was assessed by nCounter in formalin-fixed paraffin-embedded tumor samples. PTENlow status was defined by a previously validated cut-off and was correlated with castration-resistant prostate cancer (CRPC)-free survival (CRPC-FS) (primary endpoint) and overall survival (OS). RNA-Seq was performed to molecularly characterize PTENlow vs. PTENwt tumors. A total of 380 patients were included, 350 eligible. PTENlow was observed in 28.2% of patients and was independently associated with shorter CRPC-FS (HR 1.6, 95% CI 1.2-2.1, p = 0.002) and OS (HR 1.5, 95% CI 1.1-2, p = 0.014). PTENlow tumors showed overexpression of neuroendocrine, cell cycle, and DNA repair gene signatures, reduced expression of the androgen receptor pathway, and a distinct immune microenvironment. Using microarray data from the CHAARTED trial, we developed a PTEN-low related signature, independently associated with CRPC-FS (HR 1.5, 95% CI 1-2.3, p = 0.036) and OS (HR 1.9, C1 1.2-2.9, p = 0.005), and identified targets for potential therapies in PTEN-altered tumors. We conclude that PTENlow correlates with an aggressive clinical outcome in mHSPC patients and is associated with a unique transcriptional profile. These findings further support the investigation of novel therapeutic strategies for patients with PTEN alterations.