Prolactin as a Potential Early Predictive Factor in Metastatic Non-Small Cell Lung Cancer Patients Treated with Nivolumab

BACKGROUND/AIMS: Prolactin (PRL) is a peptide hormone and several studies have demonstrated its role as a cytokine in human T cell-mediated immunity. We are unaware if PRL is a positive or negative immunomodulator, but its effects on the regulation of T cells could inhibit the antitumor activity elicited by nivolumab (NIVO). We aimed to assess whether the occurrence of hyperprolactinemia in metastatic non-small cell lung cancer (mNSCLC) patients treated with NIVO is associated with poor clinical outcomes. METHODS: We evaluated 26 mNSCLC patients treated with NIVO. Blood samples were collected in every patient to evaluate PRL basal levels before starting the therapy with NIVO and before each following administration of NIVO. All patients underwent a conventional CT to investigate the effect of therapy according to Immune-related Response Evaluation Criteria in Solid Tumors (IrRECIST). RESULTS: Twenty patients (77%) developed hyperprolactinemia during the treatment, whereas 6 patients (23%) had stable levels of PRL during the therapy (p = 0.001). A total of 95% of the 20 patients with hyperprolactinemia had progressive disease (PD), according to CT results, whereas only 2 patients (33%) out of 6 with stable PRL levels had PD (p = 0.004). CONCLUSIONS: Hyperprolactinemia in mNSCLC patients treated with NIVO could potentially represent a negative early predictive factor for poor clinical outcomes, thus anticipating PD shown by CT scan