LAUSR

We read with interest the recent review by Pyo et al. [1] on the diagnostic and prognostic role of mean platelet volume (MPV) in malignant tumors. The authors reported that the MPV level was significantly higher in patients with malignant tumors than in healthy subjects, and decreased following treatment. MPV represents the average platelet size in the bloodstream and may also reflect platelet activity. The first-line treatment of lung cancer includes platinumbased chemotherapy as standard for the majority of patients with advanced non-small cell lung cancer (NSCLC), without comorbidities and with optimal performance status [2]. However, the use of immune check point inhibitors (ICIs) to treat NSCLC is a recent approach which has generated significant interest. One such ICI is the programmed death (PD)-1 inhibitor nivolumab, which is approved in the United States for the treatment of metastatic NSCLC in patients with disease progression or following platinum-based chemotherapy As a paraneoplastic surrogate index for host immune response and inflammation status, the prognostic value of neutrophil-tolymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) has been demonstrated in a variety of cancers [3]. In addition, platelet indices such as platelet count, MPV, and platelet distribution (PDW) can be used to evaluate lung cancer or histology [4]. Although the significance of NLR in nivolumab-treated patients with NSCLC has been reported [5], platelet indices after nivolumab treatment are poorly understood. We therefore evaluated platelet indices after nivolumab treatment in patients with NSCLC. We recruited 52 nivolumab-treated patients with NSCLC and assigned them to one of two groups according to nivolumab dosage cycle. Good treatment response resulted in increased dosage cycles of PD-1 antibody, but failure to progress was associated with treatment discontinuation. We compared the two groups, which were 30 good responders (GR) received nivolumab for more than 12 cycles and 22 bad responders (BR) received less than 3 cycles (Table I).We analyzed the platelet indices measured 2 weeks after initial nivolumab treatment, and found that platelet count and PLR were significantly higher in the BR group than in the GR group. In contrast, PDW, MPV, and platelet large cell ratio (P-LCR) [6] were significantly lower in the BR group than in the GR group. P-LCR is an indicator of larger platelet circulating (>12fl) and has also been used to monitor platelet activity [6]. Recently, Negash et al. [7] reported that PDW, MPV, and P-LCR help in predicting thrombocytopenic patients as having immune thrombocytopenia or hypoproductive thrombocytopenia. To the best of our knowledge, our study is the first to demonstrate a correlation between platelet indices and nivolumab treatment in patients with NSCLC. Previous reports showed that the prognosis of patients with high MPV or high PLR levels was wrong [3,4]. In addition, Omar et al. [8] reported that decreased MPV/platelet count ratio was a useful indicator of poor prognostic in lung cancer. However, in these studies, platelet biomarkers were measured prior to treatment. In contrast, we evaluated platelet data collected 1 week after the initiation of nivolumab treatment. Our findings indicate that increased MPV is related to good prognosis. In a randomized phase III study, second-line treatment with nivolumab versus docetaxel, nivolumab significantly improved overall survival, progression-free survival, patient-reported outcomes, and safety and tolerability compared with docetaxel [9]. Thus, nivolumab represents an important new strategy for previously treated patients with advanced nonsquamous NSCLC [10]. However, it remains unclear whether ICIs should be positioned as first-line treatment for NSCLC [11], and the establishment of relevant prognostic markers is therefore critical. Pyo et al. [1] have suggested that MPV levels can be used for screening malignant tumors and predicting prognosis. Our findings also indicate the potential of platelet indices in the diagnosis of lung cancer. However, Pyo et al. [1] have also indicated that cumulative studies are required before the usefulness of MPV can be confirmed in this setting. Therefore, further investigation is required into the role of platelet indices in lung cancer.