Anti–programmed cell death 1 (PD-1) antibodies, an immune checkpoint inhibitor (ICI), exert antitumor effects by suppressing the immune tolerance to cancer cells. Recent clinical trials have demonstrated such antitumor effects, and these antibodies are approved for use for the treatment of several advanced cancers.^1-5 However, ICI-related adverse events are observed in patients receiving anti–PD-1 antibodies. Among them, ICI-induced interstitial lung disease (ICI-ILD) is a clinically serious and life-threatening toxic effect.^6,7 The reported prevalence of ICI-ILD is 4.1% in patients with lung cancer, 4.1% in patients with kidney cell carcinoma, and 1.6% in patients with malignant melanoma.⁸ Therefore, it is important to determine the risk factors for ICI-ILD to pay more attention to the development of ICI-ILD and initiate prompt treatment in patients with risk factors.

To describe the treatment patterns and determine the effectiveness and safety of nivolumab treatment for non-small cell lung cancer (NSCLC) in real-world setting in Japan. Japanese patients with NSCLC who received nivolumab were analyzed retrospectively. Patients who had started nivolumab treatment between April 2016 and December 2016 were enrolled. Information regarding patient demographics and clinical backgrounds, treatment patterns from diagnosis to post-nivolumab treatment, effectiveness and safety of nivolumab treatment and that of treatments just before and after nivolumab treatment, and programmed death-ligand 1 (PD-L1) expression status, if available, were collected. Factors associated with nivolumab effectiveness identified by univariate and multivariate analyses were further investigated for plotting Kaplan-Meier curves of epidermal growth factor receptor (EGFR) gene mutation status, PD-L1 expression status, and Eastern Cooperative Oncology Group performance status (ECOG PS). In this study, 901 NSCLC patients were enrolled. Nivolumab was used the most as a second line treatment with a median number of nivolumab doses of five. The median overall survival (OS) was 14.6 months, one-year survival rate was 54.3 %, and median progression-free survival (PFS) was 2.1 months. The objective response rate was 20.5 % and disease control rate was 57.4 %. According to multivariate analyses, better OS and PFS were associated with favorable ECOG PS and absence of liver metastasis. Better PFS was observed in patients without EGFR mutation and patients with smoking history. PFS and best overall response in PD-L1 expression subgroups were expression level-dependent. The overall incidence of irAEs was 45.8 %, and the incidence of adverse events of grade 3 or higher was 14.0 %. The real-world effectiveness and safety of nivolumab is consistent with that reported by previous clinical trials and other real-world data. Subgroup analysis showed that ECOG PS, EGFR mutation status, smoking status, and PD-L1 were associated with the effectiveness of nivolumab.

Plasminogen activator inhibitor‐1 (PAI‐1) promotes pulmonary fibrosis through increasing myofibroblast (MF) characteristics, expressing alpha‐smooth muscle actin (α‐SMA) in fibroblasts. Fibroblasts in the tumour stroma are called cancer‐associated fibroblasts (CAFs). Some CAFs have MF characteristics and substantially promote tumour progression and chemotherapy resistance. This study determined whether inhibition of PAI‐1 suppressed MF characteristics of CAFs and limited chemotherapy resistance in lung cancer. To investigate cellular PAI‐1 expression and its correlation with α‐SMA expression of CAFs, 34 patients’ paraffin‐embedded lung adenocarcinoma tissue sections were immunohistochemically stained for PAI‐1 and α‐SMA. Immunohistochemical analysis of lung adenocarcinoma tissues showed that PAI‐1 expression was correlated with that of α‐SMA (r = 0.71, p < 0.001). Furthermore, in vitro, α‐SMA expression of CAFs was limited by PAI‐1 inhibition, and apoptosis of CAFs was increased. In addition, the effectiveness of cisplatin on lung cancer cells co‐cultured with CAFs was increased by suppressing α‐SMA expression using PAI‐1 inhibitor. In lung adenocarcinoma tissues, PAI‐1 expression was associated with T factor and TNM stage. Our data suggest that inhibition of PAI‐1 increased the chemotherapeutic effect on lung cancer through suppressing the MF characteristics of CAFs. Hence, PAI‐1 might be a promising therapeutic target for patients with chemotherapeutic‐resistant lung cancer with CAFs.