Treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) improves the overall survival of patients with EGFR-mutated non-small-cell lung cancer (NSCLC). First-generation EGFR-TKIs (e.g., gefitinib and erlotinib) or second-generation EGFR-TKIs (e.g., afatinib and dacomitinib) are effective for the treatment of EGFR-mutated NSCLC, especially in patients with EGFR exon 19 deletions or an exon 21 L858R mutation. However, almost all cases experience disease recurrence after 1 to 2 years due to acquired resistance. The EGFR T790M mutation in exon 20 is the most frequent alteration associated with the development of acquired resistance. Osimertinib—a third-generation EGFR-TKI—targets the T790M mutation and has demonstrated high efficacy against EGFR-mutated lung cancer. However, the development of acquired resistance to third-generation EGFR-TKI, involving the cysteine residue at codon 797 mutation, has been observed. Other mechanisms of acquired resistance include the activation of alternative pathways or downstream targets and histological transformation (i.e., epithelial–mesenchymal transition or conversion to small-cell lung cancer). Furthermore, the development of primary resistance through overexpression of the hepatocyte growth factor and suppression of Bcl-2-like protein 11 expression may lead to problems. In this report, we review these mechanisms and discuss therapeutic strategies to overcome resistance to EGFR-TKIs.

Purpose: Although the efficacy of programmed cell death–1 (PD-1) blockade is generally poor for non–small cell lung cancer (NSCLC) with activating mutations of the epidermal growth factor receptor (EGFR) gene, EGFR tyrosine kinase inhibitors (TKIs) may improve the tumor immune microenvironment. We performed a randomized study to assess whether nivolumab improves outcome compared with chemotherapy in such patients previously treated with EGFR-TKIs. Patients and Methods: Patients with EGFR-mutated NSCLC who acquired EGFR-TKI resistance not due to a secondary T790M mutation of EGFR were randomized 1:1 to nivolumab (n = 52) or carboplatin–pemetrexed (n = 50). The primary endpoint was progression-free survival (PFS). Results: Median PFS and 1-year PFS probability were 1.7 months and 9.6% for nivolumab versus 5.6 months and 14.0% for carboplatin–pemetrexed [log-rank P < 001; hazard ratio (HR) of 1.92, with a 60% confidence interval (CI) of 1.61–2.29]. Overall survival was 20.7 and 19.9 months [HR, 0.88 (95% CI, 0.53–1.47)], and response rate was 9.6% and 36.0% for nivolumab and carboplatin–pemetrexed, respectively. No subgroup including patients with a high tumor mutation burden showed a substantially longer PFS with nivolumab than with carboplatin-pemetrexed. The T-cell–inflamed gene expression profile score (0.11 vs. −0.17, P = 0.036) and expression of genes related to cytotoxic T lymphocytes or their recruitment were higher in tumors that showed a benefit from nivolumab. Conclusions: Nivolumab did not confer a longer PFS compared with carboplatin-pemetrexed in the study patients. Gene expression profiling identified some cases with a favorable tumor immune microenvironment that was associated with nivolumab efficacy.

Lung cancer is the leading cause of cancer-related death worldwide.¹ Non–small cell lung cancer (NSCLC) accounts for 76% of lung cancers, and one-third of NSCLCs are locally advanced.^2,3 Unresectable, locally advanced NSCLC is considered potentially curable, but the 10-year progression-free survival (PFS) rate of patients receiving concurrent chemoradiotherapy (CRT) is only approximately 10%.⁴ Treatment with durvalumab, an anti–programmed cell death ligand 1 (PD-L1) antibody, after concurrent CRT improves survival in patients with unresectable, locally advanced NSCLC and became the standard treatment after the PACIFIC trial.⁵ However, some patients are not candidates for concurrent CRT, and 20% to 30% of patients cannot receive durvalumab due to adverse events (AEs) or poor performance status following concurrent CRT or pre-existing comorbidities.^6,7 In particular, neutropenia (≥grade 3) develops in 18% to 53% of cases, febrile neutropenia in 3% to 8%, with concurrent CRT.^8,9 Radiotherapy often has to be interrupted due to these AEs. New studies are needed to fulfill this enduring unmet need.

Background and objective: Endobronchial ultrasonography with a guide sheath transbronchial biopsy (EBUS‐GS TBB) has been used to diagnose peripheral pulmonary lesions (PPLs). In this study, we evaluated the diagnostic utility of conventional TBB after EBUS‐GS TBB.Methods: A retrospective analysis of patients who underwent conventional TBB after EBUS‐GS TBB for PPL between August 1, 2012 and December 31, 2014. We performed multivariate analysis to examine the association of various clinical factors, including EBUS probe distance and sample size area, with diagnostic yield.Results: Of 88 eligible patients, 57 (65%) were successfully diagnosed by EBUS‐GS TBB. In 31 patients not diagnosed by EBUS‐GS TBB, 15 (48%) were successfully diagnosed by additional conventional TBB. Ground glass opacity (GGO) was a significant factor associated with the diagnostic yield of additional conventional TBB following EBUS‐GS TBB. Multivariate analysis and receiver operator curves revealed that distance between the PPL and the EBUS probe of less than 2.55 mm favored the utility of conventional TBB.Conclusion: Additional conventional TBB after EBUS‐GS TBB could be a useful procedure for the diagnosis of ground glass opacity PPLs and in cases of a distance of less than 2.55 mm between the EBUS probe and the lesion.

Immune checkpoint inhibitors (ICIs) have drastically changed the clinical care of cancer. Although cancer immunotherapy has shown promise in various types of malignancies, thus far, the proportion of patients who can benefit from ICIs is relatively small. Immune-related adverse events and high cost are unavoidable problems. Therefore, biomarkers defining patients that are most likely to benefit from ICIs are urgently needed. The expression of programmed cell death-ligand 1 (PD-L1) is a logical biomarker for the prediction of response to anti-PD1/PD-L1 immunotherapies. However, its usefulness is currently debatable because of its varied definition, threshold, and spatial/temporal heterogeneity. Recently, it was reported that the tumor mutational burden, expression of neoantigens, mismatch repair status, and specific gene mutations may be markers for the success of treatment with ICIs. Moreover, it was suggested that the fecal microbiota prior to immunotherapy may play an important role in predicting the efficacy of ICIs. In this review, we focused on these potential biomarkers for cancer immunotherapy reported in recent clinical articles. Further studies are warranted to develop a predictive model using these biomarkers, with the aim of practicing precision medicine in cancer immunotherapy.

Immune checkpoint inhibitors (ICIs) have emerged as promising therapeutic agents in non-small cell lung cancer (NSCLC). However, the duration for which ICIs should be continued remains a clinical problem. We examined the efficacy of anti-PD-1/PD-L1 inhibitors after the discontinuation of antibodies due to adverse events (AEs) in patients with NSCLC. This was a multicenter retrospective study that analyzed NSCLC patients who were treated with PD-1/PD-L1 inhibitors by August 2016. The patients with NSCLC were 18 males and 1 female at a median 67 years of age (range: 49–80 years). Eighteen of 19 patients were treated with nivolumab, one was with atezolizumab. Approximately half of AEs were interstitial pneumonia. Fourteen patients (73.7%) were treated with steroid therapy. The median number of treatment cycles was 7 (range, 1–70), and the median duration of treatment was 2.8 months (range, 1 day-32.9 months). The overall response rate with confirmation during treatment was 21.1%. The median progression-free survival (PFS) was 10.2 months (95% confidence interval [CI] = 3.2–17.1 months) and 5.6 months (95% CI = 0–12.2 months) from the initiation and the discontinuation of PD-1/PD-L1 treatment, respectively. The median PFS after discontinuation according to the confirmed response during administration was not reached for partial response (PR) and 4.9 months (95% CI, 3.7–6.0) for stable disease (SD) patients (P = 0.02). The PFS of the PR patients was completely different from that of the SD patients. The cases with PR prior to the onset of AE tended to show a durable response after the discontinuation of PD-1/PD-L1 inhibitors.