Noboru Hattori

Background: Immune checkpoint inhibitors (ICIs) improve the prognosis of patients with previously treated non‐small cell lung cancer (NSCLC). However, the efficacy and safety of ICIs for patients with NSCLC complicated with interstitial pneumonia (IP) remain unknown. This study aimed to analyze patients with NSCLC and IP treated with ICIs and to investigate the efficacy and exacerbation frequency of ICI therapy. Methods: We prospectively enrolled patients with NSCLC and IP at multiple centers and examined progression‐free survival (PFS) and overall survival (OS) using the Kaplan–Meier method. Results: The median PFS was 5.8 months, and the median OS was 9.7 months. ICI‐related lung injury was observed in seven of the 19 patients (36.8%). Pneumonitis was observed in one of five patients with a usual interstitial pneumonia (UIP) pattern and in six of 14 patients with a non‐UIP pattern; however, there was no significant difference in onset frequency. Furthermore, we observed no significant difference in PFS between patients with and without ICI‐related pneumonitis (6.8 vs. 3.3 months, respectively; p = 0.826). OS tended to be shorter in patients with ICI‐related pneumonitis, but the difference was not significant (8.0 vs. 16.7 months, respectively; p = 0.172). Conclusions: The use of ICIs in patients with NSCLC and IP produces long‐term responses in some cases; however, there is a high possibility of ICI‐related pneumonitis. In cases where the condition worsens, post‐treatment may be difficult, and the prognosis may be poor.

Background: Drug‐induced lung disease (DILD) is a severe adverse event of cancer treatment. Several clinical reports have demonstrated an association between DILD and tumor progression. However, the underlying mechanism remains unclear. This study aimed to elucidate the role of tumor‐bearing status in the development of DILD. Methods: We prepared a subcutaneous Lewis lung carcinoma (LLC) and KLN205‐bearing model. To trigger DILD, bleomycin (BLM) was administered subcutaneously. mRNA expression associated with endothelial activation (PAI‐1, vWF, and ICAM‐1), inflammatory cell infiltration, and alveolar wall thickness was assessed by using bronchioalveolar lavage fluid (BALF) and lung tissue. Additionally, the role of high‐mobility group box 1 (HMGB1) in tumor‐bearing status was examined. Results: Compared with control mice, LLC‐ and KLN205‐bearing mice showed a tendency toward increased expression of at least one of PAI‐1, vWF, and ICAM‐1 on endothelium, along with inflammatory cell infiltration in the lungs. BLM‐treated mice with LLC showed more inflammatory cell infiltration than BLM‐treated mice, accompanied by a significant increase in PAI‐1, vWF, and ICAM‐1 expression on endothelium. Moreover, BLM‐treated mice with LLC exhibited pronounced alveolar wall thickening. In LLC‐bearing mice, serum HMGB1 levels were significantly higher compared with control mice. Additionally, inflammatory cell infiltration in the lungs tended to be increased by the intraperitoneal injection of HMGB1, which was accompanied by increased expression of vWF and ICAM‐1 on endothelium. Conclusions: This study showed that tumor‐bearing status elicits proinflammatory activation in endothelial cells and inflammatory cell infiltration into the lungs that aggravates DILD caused by BLM.

Supplementary Figure S11 shows schematic illustration of our study.

Immune checkpoint inhibitors (ICI) have improved the prognosis of patients with non–small cell lung cancer (NSCLC), but the cure rate remains low because tolerant persister cancer cells can survive within the tumor during ICI treatment. We have previously reported that plasminogen activator inhibitor-1 (PAI-1) is involved in tolerance acquisition to osimertinib in EGFR-mutated NSCLC. This study aimed to examine the role of PAI-1 in ICI tolerance and whether PAI-1 may be a therapeutic target to overcome this tolerance. In a mouse subcutaneous tumor model using Lewis lung carcinoma or KLN205 cells, cancer cells surviving within the tumor 7 days after anti–PD-1 (aPD-1) antibody treatment were defined as aPD-1 antibody–tolerant persister cells (aPD-1-TP). PAI-1 and mesenchymal gene expression levels were higher in aPD-1-TPs than in control cells. IHC analyses showed higher numbers of tumor-associated macrophages, expression of PD-L1 in cancer cells, and degree of angiogenesis. In contrast, the number of tumor-infiltrating lymphocytes was lower in aPD-1 antibody–tolerant tumors than in control tumors. Combination treatment with an aPD-1 antibody and the PAI-1 inhibitor, TM5614 decreased mesenchymal gene expression, PD-L1 expression, tumor-associated macrophage numbers, and angiogenesis and increased tumor-infiltrating lymphocyte counts in tolerant tumors. Furthermore, it resulted in prolonged inhibition of tumor growth. In conclusion, this study underscores the involvement of PAI-1 in the survival of aPD-1-TPs via epithelial–mesenchymal transition and alteration of the tumor microenvironment. Combination treatment with an aPD-1 antibody and TM5614 can be a new therapeutic strategy for NSCLC.

Supplementary Figure S9 shows tumor microenvironment of tumors composed of LLC and KLN205 cells.

Supplementary Figure S8 shows relationship of TGF-β secretion with TAMs and CAFs.

Supplementary Figure S4 shows that SK-216 significantly increases the antitumor efficacy of aPD-1.

Supplementary Figure S10 shows degree of angiogenesis in the tumors treated with aPD-1 antibody or aPD-1 antibody with TM5614.

Supplementary Figure S1 shows the experimental scheme for aPD-1 antibody-tolerant cells and the induction of PAI-1 expression during tumor regrowth.

Supplementary Figure S2 shows tumor expression level of PAI-1 in surgically resected NSCLC samples.