Impact of central nervous system metastasis after complete resection of lung adenocarcinomas harboring common EGFR mutation - A real-world database study in Japan: The CReGYT-01 EGFR study.

OBJECTIVES: To clarify the impact of central nervous system (CNS) metastasis on performance status (PS) at relapse, on subsequent treatment(s), and on survival of patients with lung adenocarcinoma harboring common epidermal growth factor receptor (EGFR) mutation. METHODS: We conducted the multicenter real-world database study for patients with radical resections for lung adenocarcinomas between 2015 and 2018 at 21 centers in Japan. EGFR mutational status was examined at each center. RESULTS: Of 4181 patients enrolled, 1431 underwent complete anatomical resection for lung adenocarcinoma harboring common EGFR mutations. Three-hundred-and-twenty patients experienced disease relapse, and 78 (24%) had CNS metastasis. CNS metastasis was significantly more frequent in patients with conventional adjuvant chemotherapy than those without (30% vs. 20%, P = 0.036). Adjuvant chemotherapy did not significantly improve relapse-free survival at any pathological stage (adjusted hazard ratio for stage IA2-3, IB, and II-III was 1.363, 1.287, and 1.004, respectively). CNS metastasis did not affect PS at relapse. Subsequent treatment, mainly consisting of EGFR-tyrosine kinase inhibitors (TKIs), could be equally given in patients with or without CNS metastasis (96% vs. 94%). Overall survival after relapse was equivalent between patients with and without CNS metastasis. CONCLUSION: The efficacy of conventional adjuvant chemotherapy may be limited in patients with lung adenocarcinoma harboring EGFR mutations. CNS metastasis is likely to be found in practice before deterioration in PS, and may have little negative impact on compliance with subsequent EGFR-TKIs and survival after relapse. In this era of adjuvant TKI therapy, further prospective observational studies are desirable to elucidate the optimal management of CNS metastasis.

Novel quantitative immunohistochemical analysis for evaluating PD-L1 expression with phosphor-integrated dots for predicting the efficacy of patients with cancer treated with immune checkpoint inhibitors.

Introduction: Programmed cell death ligand 1 (PD-L1) expression in tumor tissues is measured as a predictor of the therapeutic efficacy of immune checkpoint inhibitors (ICIs) in many cancer types. PD-L1 expression is evaluated by immunohistochemical staining using 3,3´-diaminobenzidine (DAB) chronogenesis (IHC-DAB); however, quantitative and reproducibility issues remain. We focused on a highly sensitive quantitative immunohistochemical method using phosphor-integrated dots (PIDs), which are fluorescent nanoparticles, and evaluated PD-L1 expression between the PID method and conventional DAB method. Methods: In total, 155 patients with metastatic or recurrent cancer treated with ICIs were enrolled from four university hospitals. Tumor tissue specimens collected before treatment were subjected to immunohistochemical staining with both the PID and conventional DAB methods to evaluate PD-L1 protein expression. Results: PD-L1 expression assessed using the PID and DAB methods was positively correlated. We quantified PD-L1 expression using the PID method and calculated PD-L1 PID scores. The PID score was significantly higher in the responder group than in the non-responder group. Survival analysis demonstrated that PD-L1 expression evaluated using the IHC-DAB method was not associated with progression-free survival (PFS) or overall survival (OS). Yet, PFS and OS were strikingly prolonged in the high PD-L1 PID score group. Conclusion: Quantification of PD-L1 expression as a PID score was more effective in predicting the treatment efficacy and prognosis of patients with cancer treated with ICIs. The quantitative evaluation of PD-L1 expression using the PID method is a novel strategy for protein detection. It is highly significant that the PID method was able to identify a group of patients with a favorable prognosis who could not be identified by the conventional DAB method.

A case of discordant histology and expression of programmed death ligand 1 between primary tumor and brain metastases in adenosquamous carcinoma of the lung.

A patient presented with vomiting and gait disturbance. Investigation revealed a single cerebellar tumor and another tumor in the upper lobe of the left lung. Based on the severe vomiting and gait disturbance, we removed the cerebellar tumor first, achieving resolution of symptoms. The cerebellar tumor was pathologically diagnosed as metastatic lung adenocarcinoma. No other metastases were identified, including in the mediastinal lymph nodes. We therefore resected the primary lung tumor. On final pathological analysis, the tumor in the upper lobe of the left lung was diagnosed as adenosquamous carcinoma with no lymph node metastasis. PD-L1 expression was low in the primary lung adenosquamous carcinoma and high in the cerebellar metastasis. Furthermore, both tumors were KRASG12C -positive. Tumor PD-L1 expression is considered important for immune escape. In this case, adenocarcinoma cells in the primary adenosquamous carcinoma may have migrated to form a cerebellar metastasis. In advanced lung cancer, tumor growth may be observed in some lesions even when many other lesions are controlled by chemo- or immunotherapy. Biopsy to confirm histology and PD-L1 expression is worth considering, depending on the location of the metastases and the invasiveness of the biopsy procedure.

Hochuekkito exerts the anti-allergic effects via activating regulatory T cells in a murine model of contact hypersensitivity.

Hochuekkito (HET) is a Kampo prescription, used for the clinical treatment of skin diseases such as atopic dermatitis (AD), in Japan. Oral administration of HET exerts anti-allergic effects in an experimental dermatitis mice model and in patients with atopic dermatitis; however, the mechanism underlying the anti-allergic effects of HET is still unclear. Therefore, we investigated the immunopharmacological properties of the anti-allergic actions of HET using a 2,4,6-trinitrochlorobenzene (TNCB)-induced murine contact hypersensitivity (CHS) model and adoptive cell transfer experiments. Oral administration of HET (1.4 g/kg) exhibited anti-allergic effects in a TNCB-induced CHS model via activation of Tregs; this activation was observed even without antigen sensitization in donor mice. Activation was dependent on the duration of HET administration and required at least 4 days of dosing. In addition, the anti-allergic effects of HET through the activation of Tregs were not antigen specific. Flow cytometry results indicated that the proportion of CD4+CD25+Foxp3+ cells in the splenic lymphocytes increased after oral administration of HET. Therefore, oral administration of HET induced both inducible regulatory T cells (iTregs) and thymus-derived naturally occurring regulatory T cells (nTregs). Ginseng radix and Bupleuri radix were involved in the anti-allergic actions of HET through the induction and/or activation of Tregs; Bupleuri radix participated in the activation of nTregs. In conclusion, our findings suggest that HET exerts the anti-allergic effects through the induction and/or activation of Tregs. These findings elucidate the usefulness of HET as an immunomodulator.

[Clinical Features of Endocrine Disorders with Immune Checkpoint Inhibitor in Patients with Non-Small Cell Lung Cancer].

Immune checkpoint inhibitors(ICIs)could cause immune-related adverse events(irAEs), of which endocrine disorders are relatively common. Symptoms include fatigue, anorexia, and shock, making diagnosis and treatment difficult. This study aimed to analyze the characteristics of patients with non-small cell lung cancer concomitant with endocrine disorders as irAEs. In total, 83 patients who were administered ICIs for advanced or postoperative recurrent non-small cell lung cancer between February 2016 and February 2021 were identified. We retrospectively studied the clinical course and findings of 7 patients who developed endocrine disorders after treatment. Four patients had hypopituitarism, and 3 patients had thyroid dysfunctions. There were 6 male patients and 1 female patient. Regarding anticancer agents, 5 patients received ICI alone, and 2 patients received ICI plus cytotoxic chemotherapies. The patients received treatment from the irAE treatment team in our hospital, and 5 of 7 patients could were able to be readministered ICIs. Endocrine disorders as irAEs require collaboration with specialized departments for early diagnosis and treatment.

Wnt/ß-Catenin Signaling and Resistance to Immune Checkpoint Inhibitors: From Non-Small-Cell Lung Cancer to Other Cancers.

Lung cancer is the leading cause of cancer-related deaths worldwide. The standard of care for advanced non-small-cell lung cancer (NSCLC) without driver-gene mutations is a combination of an anti-PD-1/PD-L1 antibody and chemotherapy, or an anti-PD-1/PD-L1 antibody and an anti-CTLA-4 antibody with or without chemotherapy. Although there were fewer cases of disease progression in the early stages of combination treatment than with anti-PD-1/PD-L1 antibodies alone, only approximately half of the patients had a long-term response. Therefore, it is necessary to elucidate the mechanisms of resistance to immune checkpoint inhibitors. Recent reports of such mechanisms include reduced cancer-cell immunogenicity, loss of major histocompatibility complex, dysfunctional tumor-intrinsic interferon-γ signaling, and oncogenic signaling leading to immunoediting. Among these, the Wnt/ß-catenin pathway is a notable potential mechanism of immune escape and resistance to immune checkpoint inhibitors. In this review, we will summarize findings on these resistance mechanisms in NSCLC and other cancers, focusing on Wnt/ß-catenin signaling. First, we will review the molecular biology of Wnt/ß-catenin signaling, then discuss how it can induce immunoediting and resistance to immune checkpoint inhibitors. We will also describe other various mechanisms of immune-checkpoint-inhibitor resistance. Finally, we will propose therapeutic approaches to overcome these mechanisms.

Myeloid-derived suppressor cells: Cancer, autoimmune diseases, and more.

Although cancer immunotherapy using immune checkpoint inhibitors (ICIs) has been recognized as one of the major treatment modalities for malignant diseases, the clinical outcome is not uniform in all cancer patients. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells that possess various strong immunosuppressive activities involving multiple immunocompetent cells that are significantly accumulated in patients who did not respond well to cancer immunotherapies. We reviewed the perspective of MDSCs with emerging evidence in this review. Many studies on MDSCs were performed in malignant diseases. Substantial studies on the participation of MDSCs on non-malignant diseases such as chronic infection and autoimmune diseases, and physiological roles in obesity, aging, pregnancy and neonates have yet to be reported. With the growing understanding of the roles of MDSCs, variable therapeutic strategies and agents targeting MDSCs are being investigated, some of which have been used in clinical trials. More studies are required in order to develop more effective strategies against MDSCs.

Ectopic adrenocorticotropic hormone-secreting carcinoid with solitary cryptococcosis in the lungs.

BACKGROUND: Carcinoid tumors can on rare occasions ectopically produce adrenocorticotropic hormone (ACTH), causing Cushing's syndrome, and patients could become immunocompromised. Care must therefore be taken regarding infectious complications. In particular, ACTH-producing pulmonary carcinoid is not easy to diagnose by itself, and when combined with pulmonary nodules as infectious foci, each is very difficult to diagnose. CASE: The patient was a 71-year-old woman with refractory diabetes. She showed clinical symptoms of Cushing's syndrome during treatment for diabetes and ectopic ACTH production was suspected based on biochemical and imaging tests. Nodules were identified in the left lung apex and lingual segment. Examination of resected nodules revealed that the nodule in the apex was pulmonary cryptococcosis, while the nodule in the lingual segment represented typical carcinoid. After surgery, clinical symptoms, laboratory findings, and diabetes all improved. CONCLUSION: We present this very instructive case in terms of the difficulty of diagnosing ACTH-producing tumors, the possibility of infection complicating the immunodeficiency caused by ACTH-producing tumors, and the surgical strategy.

Lung adenocarcinoma coexisting with diffuse idiopathic pulmonary neuroendocrine cell hyperplasia manifesting as multiple pulmonary nodules: A case report.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH), a rare condition, is characterized by pathological proliferation of neuroendocrine cells. Some of them are localized to the airway mucosa, and others locally infiltrate to form tumorlets and nodules. Here, we present a patient with lung adenocarcinoma accompanied by DIPNECH, making the latter difficult to distinguish from multiple pulmonary metastases. The patient, a 72-year-old Japanese woman, was diagnosed as having stage IVA lung adenocarcinoma because she had multiple nodules in both lungs. Mutation of epidermal growth factor receptor gene having been found in the primary tumor, treatment with osimertinib was started. This resulted in shrinkage of the primary tumor, but not the multiple pulmonary nodules. To determine whether these lung nodules were indeed lung metastases, we performed right upper lobectomy with lymphadenectomy and wedge resection of the right lower lobe. On pathological examination, the primary tumor was diagnosed as invasive adenocarcinoma, whereas the multiple pulmonary nodules were diagnosed as DIPNECH manifesting as tumorlets. Therefore, the final diagnosis was stage IA1 lung adenocarcinoma accompanied by DINPECH. The patient had no recurrences 1 year after the operation without any additional treatment. This is a rare case of lung adenocarcinoma accompanied by DIPNECH presenting as multiple pulmonary nodules. DIPNECH should be included in the differential diagnosis of multiple pulmonary nodules.

[Resistance Mechanisms to Immune Checkpoint Inhibitor and Its Overcome with Focus on ß-Catenin in Lung Cancer].

Although the indications for immune checkpoint inhibitors are expanding rapidly, the disease will eventually progress in many patients. Elucidating and overcoming the resistant mechanisms to immune checkpoint inhibitors is a major challenge. WNT/ß-catenin pathway has long been known as one of the mechanisms involved in cell proliferation and epithelial-mesenchymal transition in cancer development. Recently, it has become clear that WNT/ß-catenin pathway also plays a role in cancer immune escape, as reported in melanoma. We have also studied WNT/ß-catenin pathway as a mechanism of immune escape in lung cancer. In this article, we review how WNT/ß-catenin pathway is involved in immune escape and resistance to immune checkpoint inhibitors, mainly in non-small cell lung cancer. In addition, we discuss how to overcome the tumor immune mechanism caused by WNT/ß-catenin pathway in the context of current combination therapies and therapies in development.

[ß-Catenin Expression in Non-Small Cell Lung Cancer and Therapeutic Effect of Immune Checkpoint Inhibitors].

Recently, ß-catenin mediated immune escape mechanism has been reported in several cancers. We investigated whether ß-catenin is associated with resistance to immune checkpoint inhibitor therapy in non-small cell lung cancer. Non-small cell lung cancer patients expressing high levels of ß-catenin showed poor progression-free survival and overall survival after single agent anti-PD-1 therapy. They had less infiltration of CD8-positive cells and antigen-presenting cells. Microarray analysis also showed low gene expression of CD8A and IFNG. siRNA knockdown of CTNNB1 in the ß-catenin-positive lung cancer cell line LK-2 tended to decrease CTNNB1 and ATF3 expression and increase CCL4 expression. The results suggest that ß- catenin suppresses tumor infiltration by antigen-presenting cells and confers resistance to immune checkpoint inhibitors in non-small cell lung cancer via downregulation of CCL4 production.

Large cell neuroendocrine carcinoma of the lung controlled for 4 years by a single administration of pembrolizumab: A case report.

Large cell neuroendocrine carcinoma of the lung (LCNEC) is a rare and highly progressive tumor with a poor prognosis. Although immune checkpoint inhibitors have been approved for treatment of both small cell and non-small cell lung cancers, their role in the treatment of LCNEC is unclear. We describe a patient with postoperative recurrence of LCNEC who maintained complete remission for 4 years after a single administration of pembrolizumab. A 68-year-old Japanese man underwent thoracoscopic right lower lobectomy for LCNEC (pathological stage pT1bN0M0, stage IA2). Epidermal growth factor receptor and anaplastic lymphoma kinase were negative, and the programmed death ligand 1 expression rate in tumor cells was 5% (clone 22C3). Eight months later, the patient developed recurrence with mediastinal lymph node metastasis and pleural dissemination. Therefore, chemotherapy with cisplatin and etoposide was administered. However, relapse occurred 6 months later. Pembrolizumab was administered as second-line chemotherapy, which was discontinued after first dose because of interstitial pneumonia 1 month later. Thereafter, however, both the lymph node metastasis and pleural dissemination disappeared and did not relapse for 4 years. Pembrolizumab may be used as a treatment option for pulmonary LCNEC.

Thoracoscopic resection of posterior mediastinal paraganglioma: perioperative management and surgical tips.

Posterior mediastinal paraganglioma (PM-PGL) is a rare disease that is difficult to diagnose. If PM-PGL is misdiagnosed preoperatively, surgeons may encounter severe tachycardia and hypertension and easy bleeding from the tumor during the operation. Therefore, it is essential to include PGL as a differential diagnosis for mediastinal tumors. We herein describe a 73-year-old Japanese man with a PM-PGL that was diagnosed preoperatively and resected safely by video-assisted thoracic surgery. Preoperative management of hypertension with doxazosin mesylate, soft coagulation of the peritumor area, and careful clipping of feeding arteries were effective for hemostasis. The patient's vital signs were stable during and after the operation.

The clinical significance of tertiary lymphoid structure and its relationship with peripheral blood characteristics in patients with surgically resected non-small cell lung cancer: a single-center, retrospective study.

INTRODUCTION: The presence of tertiary lymphoid structure (TLS) in tumor tissues has been reported to be a factor associated with a good prognosis in several types of cancers. However, the relationship between TLS formation and peripheral blood findings remains unclear. The purposes of the study were to evaluate the effect of the presence of TLS on survival and determine the peripheral blood characteristics associated with TLS formation in non-small cell lung cancer (NSCLC) patients. METHODS: A total of 147 consecutive NSCLC patients who underwent lung resection at Fukushima Medical University Hospital between 2013 and 2017 were enrolled. TLS expression was evaluated, and the relationships between clinical parameters and outcomes were analyzed. Peripheral blood mononuclear cells (PBMCs) were further analyzed by mass cytometry to characterize the TLS-positive microenvironment. RESULTS: Forty-six patients had high TLS expression, and the remaining 101 patients had low TLS expression. In stage II to IV patients (n = 35), disease-free survival was longer in the high TLS expression group (p = 0.027). A low neutrophil to lymphocyte ratio (NLR) < 2.75 in the peripheral blood was associated with high TLS expression (p = 0.003). Citrus analysis after mass cytometry assay showed that the number of cells expressing HLA-DR and CD9 in PBMCs was lower in the high TLS expression group. CONCLUSION: High TLS expression is associated with a good prognosis after surgery in stage II and III NSCLC patients. In the peripheral blood, a low NLR and few antigen-presenting cells indicate the presence of TLS in the tumor microenvironment.

CTLA-4 Expression in Tumor-infiltrating Lymphocytes Is Irrelevant to PD-L1 Expression in NSCLC.

BACKGROUND/AIM: Treatments containing ipilimumab have shown a good outcome in patients with non-small cell lung cancer (NSCLC) regardless of the PD-L1 tumor proportion score (TPS). However, the association between PD-L1 TPS and the expression of CTLA-4 in tumor-infiltrating lymphocytes is unknown. PATIENTS AND METHODS: Fifty-five NSCLC patients who underwent surgery in our hospital were included in this study. We measured the proportions of CTLA-4+ regulatory T cells, and CTLA-4+ CD8 T cells, and statistically analyzed their correlations with the PD-L1 TPS. RESULTS: Statistical correlations were found neither between the proportion of CTLA-4+ regulatory T cells to CD8 T cells and the PD-L1 TPS (p=0.2859) nor between the proportion of CTLA-4+ cells in CD8 T cells and the PD-L1 TPS (p=0.1919). CONCLUSION: The proportions of CTLA-4+ regulatory T cells to CD8 T cells and CTLA-4+ cells in CD8 T cells were irrelevant to the PD-L1 TPS in NSCLC patients.

A patient with ALK-positive lung adenocarcinoma who survived alectinib-refractory postoperative recurrence for 4 years by switching to ceritinib.

Echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) rearrangements are found in ~ 5% of patients with non-small cell lung cancer (NSCLC). Several tyrosine kinase inhibitors (TKIs) have been developed for treatment of so-called ALK-positive NSCLC. In cases of tumor progression during treatment with second-generation ALK-TKIs, such as alectinib, brigatinib, or ceritinib, National Comprehensive Cancer Network guidelines propose a switch to lorlatinib, a third-generation ALK-TKI, or to cytotoxic chemotherapy. However, they do not mention switching to other second-generation ALK-TKIs. Here, we present a rare case of a 53-year-old Japanese woman, who had never smoked, with ALK-positive lung adenocarcinoma who survived alectinib-resistant postoperative recurrence for 4 years by switching to ceritinib. She underwent curative resection for lung adenocarcinoma, but the cancer recurred at the bronchial stump and mediastinal lymph nodes. After platinum-doublet chemotherapy, the patient still had a single growing liver metastasis, but the tumor was found to harbor EML4-ALK rearrangement. Therefore, the patient started to take ALK-TKIs. Alectinib was the second ALK-TKI used to treat this patient. Alectinib shrank the liver metastasis, which was surgically resected. The tumor relapsed again during continued treatment with alectinib, which was switched to ceritinib. Ceritinib was effective for the relapsed tumor and treatment continued well for 4 years. This case report suggests that, in case of tumor progression during treatment with a second-generation ALK-TKI, switching to another second-generation ALK-TKI may be one of the treatment options. Further analyses are warranted to find robust markers to determine which ALK-TKI is best for each patient.

CLDN15 is a novel diagnostic marker for malignant pleural mesothelioma.

Malignant mesothelioma is a cancer with a poor survival rate. It is difficult to diagnose mesotheliomas because they show a variety of histological patterns similar to those of various other cancers. However, since currently used positive markers for mesotheliomas may show false positives or false negatives, a novel mesothelial positive marker is required. In the present study, we screened 25 claudins and found that claudin-15 is expressed in the mesothelial cells. We made new rat anti-human claudin-15 (CLDN15) monoclonal antibodies that selectively recognize CLDN15, and investigated whether CLDN15 is a good positive marker for malignant pleural mesotheliomas (MPMs) using MPM tissue samples by immunohistochemistry and semi-quantification of the expression level using an immunoreactive score (IRS) method. Of 42 MPM samples, 83% were positive for CLDN15. The positive ratio was equal to or greater than other positive markers for MPMs including calretinin (81%), WT-1 (50%), and D2-40 (81%). In 50 lung adenocarcinoma sections, four cases were positive for CLDN15 and the specificity (92%) was comparable with other markers (90-100%). Notably, CLDN15 was rarely detected in 24 non-mesothelial tumors in the tissue microarray (12/327 cases). In conclusion, CLDN15 can be used in the clinical setting as a positive marker for MPM diagnosis.

Construction of in vitro patient-derived tumor models to evaluate anticancer agents and cancer immunotherapy.

An in vitro assay system using patient-derived tumor models represents a promising preclinical cancer model that replicates the disease better than traditional cell culture models. Patient-derived tumor organoid (PDO) and patient-derived tumor xenograft (PDX) models have been previously established from different types of human tumors to recapitulate accurately and efficiently their tissue architecture and function. However, these models have low throughput and are challenging to construct. Thus, the present study aimed to establish a simple in vitro high-throughput assay system using PDO and PDX models. Furthermore, the current study aimed to evaluate different classes of anticancer drugs, including chemotherapeutic, molecular targeted and antibody drugs, using PDO and PDX models. First, an in vitro high-throughput assay system was constructed using PDO and PDX established from solid and hematopoietic tumors cultured in 384-well plates to evaluate anticancer agents. In addition, an in vitro evaluation system of the immune response was developed using PDO and PDX. Novel cancer immunotherapeutic agents with marked efficacy have been used against various types of tumor. Thus, there is an urgent need for in vitro functional potency assays that can simulate the complex interaction of immune cells with tumor cells and can rapidly test the efficacy of different immunotherapies or antibody drugs. An evaluation system for the antibody-dependent cellular cytotoxic activity of anti-epidermal growth factor receptor antibody and the cytotoxic activity of activated lymphocytes, such as cytotoxic T lymphocytes and natural killer cells, was constructed. Moreover, immune response assay systems with bispecific T-cell engagers were developed using effector cells. The present results demonstrated that in vitro assay systems using PDO and PDX may be suitable for evaluating anticancer agents and immunotherapy potency with high reproducibility and simplicity.

Diffuse Cystic Metastases in the Lung after Nivolumab Treatment in a Patient with Non-Small Cell Lung Cancer: A Case Report.

Although diffuse cysts in the lung can be found in many diseases, they are uncommon in metastatic lung adenocarcinoma. They are even more unusual after the administration of immune checkpoint inhibitors. A case of lung adenocarcinoma that developed diffuse cysts in the lungs during treatment with nivolumab is reported. The patient was a 60-year-old woman with postoperative recurrent lung adenocarcinoma in mediastinal lymph nodes and pleural dissemination. After first-line treatment with cisplatin, pemetrexed, and bevacizumab, computed tomography (CT) showed disease progression. Treatment was then switched to nivolumab. After 5 courses of nivolumab, CT showed multiple ground-glass nodules in her lungs. After 4 more courses of nivolumab, the ground-glass nodules increased in size, and cystic air spaces appeared in their centers. The patient did not have any symptoms. Laboratory tests showed no evidence of infection or nivolumab-induced pneumonitis. Sialyl Lewis X-i antigen increased, and positron emission tomography showed abnormal uptake of 18F-fluorodeoxyglucose in these lesions. Considering this evidence, the cystic lesions were diagnosed as multiple lung metastases. Various differential diagnoses should be considered when diffuse cystic lesions are found in the lungs after the administration of immune checkpoint inhibitors.