Impacts of probiotics on the efficacies of immune checkpoint inhibitors with or without chemotherapy for patients with advanced non-small-cell lung cancer.

The relationships between the therapeutic effects of immune checkpoint inhibitors (ICIs) and the intestinal flora have attracted increasing attention. However, the effects of oral probiotics on the efficacies of ICIs used to treat non-small-cell lung cancer (NSCLC) remain unclear. We investigated the effects of probiotics on the efficacies of ICIs in patients treated with and without chemotherapy. We investigated patients with advanced NSCLC on ICI monotherapy or combination ICI and chemotherapy using the Okayama Lung Cancer Study Group Immunotherapy Database (OLCSG-ID) and the Okayama Lung Cancer Study Group Immunochemotherapy Database (OLCSG-ICD). In total, 927 patients (482 on ICI monotherapy, 445 on an ICI + chemotherapy) were enrolled. Most were male, of good performance status, smokers, and without epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase (ALK) mutations. Probiotics were administered to 19% of patients on ICI monotherapies and 17% of those on ICIs + chemotherapy. Of the former patients, progression-free survival (PFS) and overall survival (OS) were significantly better in the probiotics group (PFS 7.9 vs. 2.9 months, hazard ratio [HR] 0.54, p < .001; OS not attained vs. 13.1 months, HR 0.45, p < .001). Among patients receiving ICI and chemotherapy, there were no significant differences in PFS between those on probiotics and not but OS was significantly better in the probiotics group (PFS 8.8 vs. 8.6 months, HR 0.89, p = .43; OS not attained vs. 22.6 months, HR 0.61, p = .03). Patients on probiotics experienced better outcomes following ICI treatment.

Efficacy of gilteritinib in comparison with alectinib for the treatment of ALK-rearranged non-small cell lung cancer.

Gilteritinib is a multitarget tyrosine kinase inhibitor (TKI), approved for the treatment of FLT3-mutant acute myeloid leukemia, with a broad range of activity against several tyrosine kinases including anaplastic lymphoma kinase (ALK). This study investigated the efficacy of gilteritinib against ALK-rearranged non-small cell lung cancers (NSCLC). To this end, we assessed the effects of gilteritinib on cell proliferation, apoptosis, and acquired resistance responses in several ALK-rearranged NSCLC cell lines and mouse xenograft tumor models and compared its efficacy to alectinib, a standard ALK inhibitor. Gilteritinib was significantly more potent than alectinib, as it inhibited cell proliferation at a lower dose, with complete attenuation of growth observed in several ALK-rearranged NSCLC cell lines and no development of drug tolerance. Immunoblotting showed that gilteritinib strongly suppressed phosphorylated ALK and its downstream effectors, as well as mesenchymal-epithelial transition factor (MET) signaling. By comparison, MET signaling was enhanced in alectinib-treated cells. Furthermore, gilteritinib was found to more effectively abolish growth of ALK-rearranged NSCLC xenograft tumors, many of which completely receded. Interleukin-15 (IL-15) mRNA levels were elevated in gilteritinib-treated cells, together with a concomitant increase in the infiltration of tumors by natural killer (NK) cells, as assessed by immunohistochemistry. This suggests that IL-15 production along with NK cell infiltration may constitute components of the gilteritinib-mediated antitumor responses in ALK-rearranged NSCLCs. In conclusion, gilteritinib demonstrated significantly improved antitumor efficacy compared with alectinib against ALK-rearranged NSCLC cells, which can warrant its candidacy for use in anticancer regimens, after further examination in clinical trial settings.

Selective C-O Bond Reduction and Borylation of Aryl Ethers Catalyzed by a Rhodium-Aluminum Heterobimetallic Complex.

We report the catalytic reduction of a C-O bond and the borylation by a rhodium complex bearing an X-type PAlP pincer ligand. We have revealed the reaction mechanism based on the characterization of the reaction intermediate and deuterium-labeling experiments. Notably, this novel catalytic system shows steric-hindrance-dependent chemoselectivity that is distinct from conventional Ni-based catalysts and suggests a new strategy for selective C-O bond activation by heterobimetallic catalysis.

VEGFR2 blockade augments the effects of tyrosine kinase inhibitors by inhibiting angiogenesis and oncogenic signaling in oncogene-driven non-small-cell lung cancers.

Molecular agents targeting the epidermal growth factor receptor (EGFR)-, anaplastic lymphoma kinase (ALK)- or c-ros oncogene 1 (ROS1) alterations have revolutionized the treatment of oncogene-driven non-small-cell lung cancer (NSCLC). However, the emergence of acquired resistance remains a significant challenge, limiting the wider clinical success of these molecular targeted therapies. In this study, we investigated the efficacy of various molecular targeted agents, including erlotinib, alectinib, and crizotinib, combined with anti-vascular endothelial growth factor receptor (VEGFR) 2 therapy. The combination of VEGFR2 blockade with molecular targeted agents enhanced the anti-tumor effects of these agents in xenograft mouse models of EGFR-, ALK-, or ROS1-altered NSCLC. The numbers of CD31-positive blood vessels were significantly lower in the tumors of mice treated with an anti-VEGFR2 antibody combined with molecular targeted agents compared with in those of mice treated with molecular targeted agents alone, implying the antiangiogenic effects of VEGFR2 blockade. Additionally, the combination therapies exerted more potent antiproliferative effects in vitro in EGFR-, ALK-, or ROS1-altered NSCLC cells, implying that VEGFR2 inhibition also has direct anti-tumor effects on cancer cells. Furthermore, VEGFR2 expression was induced following exposure to molecular targeted agents, implying the importance of VEGFR2 signaling in NSCLC patients undergoing molecular targeted therapy. In conclusion, VEGFR2 inhibition enhanced the anti-tumor effects of molecular targeted agents in various oncogene-driven NSCLC models, not only by inhibiting tumor angiogenesis but also by exerting direct antiproliferative effects on cancer cells. Hence, combination therapy with anti-VEGFR2 antibodies and molecular targeted agents could serve as a promising treatment strategy for oncogene-driven NSCLC.

Characteristics of patients with EGFR-mutant non-small-cell lung cancer who benefited from immune checkpoint inhibitors.

OBJECTIVES: Immune checkpoint inhibitors (ICIs) are less effective in non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. However, a small percentage of patients with EGFR-mutant NSCLC do respond, and the characteristics of these patients are not known. Here, we identify the characteristics of patients who may respond to ICI therapy for EGFR-mutant NSCLC. PATIENTS AND METHODS: The medical records of NSCLC patients with EGFR mutations who received PD-1/PD-L1 antibody monotherapy at nine institutions were reviewed. RESULTS: In total, 58 patients with EGFR-mutant NSCLC were analyzed. Various clinical factors such as smoking history and EGFR mutation type were not associated with progression-free survival (PFS) of ICIs, while the PFS of prior EGFR tyrosine kinase inhibitors (TKIs) was inversely associated with that of ICIs. Patients who responded to prior EGFR TKIs for > 10 months exhibited a significantly shorter response to ICIs compared to those who had responded for ≤ 10 months (PFS of ICI: 1.6 vs. 1.9 months; hazard ratio: 2.54; 95% confidence interval 1.26-5.12; p = 0.009). However, patients who responded to ICIs for > 6 months responded to prior EGFR TKIs for significantly shorter periods compared to those who responded to ICIs for ≤ 6 months (PFS of prior EGFR TKI: 5.3 vs. 12.1 months; log-rank test: p = 0.0025). CONCLUSION: The duration of response to prior EGFR TKIs could be a predictive marker of ICI therapy in EGFR-mutant NSCLC patients.

Impact of previous thoracsic radiation therapy on the efficacy of immune checkpoint inhibitors in advanced non-smasll-cell lung cancer.

OBJECTIVES: Studies investigating the association between radiation therapy and the efficacy of immune checkpoint inhibitors in advanced non-small-cell lung cancer have provided inconsistent results, likely due to relatively small cohort sizes. This study investigated the effect of previous thoracic radiation therapy on the efficacy of immune checkpoint inhibitor therapy in a large non-small-cell lung cancer cohort. PATIENTS AND METHODS: We conducted a retrospective cohort study using data from 531 non-small-cell lung cancer patients who received monotherapy with programmed cell death protein 1/programmed death-ligand 1 inhibitors at nine institutions. The effects of thoracic radiation therapy on the efficacy of immune checkpoint inhibitors were investigated. RESULTS: A total of 531 non-small-cell lung cancer patients treated with immune checkpoint inhibitors were included in this study. The progression-free survival period was significantly longer in patients that had received thoracic radiation therapy before immune checkpoint inhibitor therapy compared to those without previous thoracic radiation therapy (median progression-free survival 5.0 vs. 3.0 months, P = 0.0013). A multivariate analysis showed that thoracic radiation therapy was an independent predictive factor of improved progression-free survival (hazard ratio of progression-free survival: 0.79, P = 0.049). In contrast, extra-thoracic radiation therapy was associated with inferior outcomes (median progression-free survival 3.0 vs. 4.2 months, P = 0.0008). CONCLUSION: Previous thoracic radiation therapy, but not prior extra-thoracic radiation therapy, enhanced the efficacy of anti-programmed cell death protein 1/programmed death-ligand 1 therapy in non-small-cell lung cancer patients.

Utility of immune checkpoint inhibitors in non-small-cell lung cancer patients with poor performance status.

Most clinical trials of non-small-cell lung cancer (NSCLC) exclude patients with poor ECOG performance status (PS). Thus, the efficacy of immune checkpoint inhibitors (ICIs) in patients with poor PS remains unclear. Herein, we used data from a retrospective cohort to assess the potential clinical benefits of ICIs in NSCLC patients with poor PS. Data from NSCLC patients who received ICI monotherapy at 9 institutions between December 2015 and May 2018 were retrospectively analyzed. After excluding 4 patients who lacked PS data, a total of 527 ICI-treated patients, including 79 patients with PS 2 or higher, were used for our analyses. The progression-free survival (PFS) and overall survival (OS) of patients with PS 2 or higher were significantly shorter compared with those of PS 0-1 patients (median PFS, 4.1 vs 2.0 months; P < .001 and median OS, 17.4 vs 4.0 months; P < .001). Among NSCLC patients with programmed cell death protein-ligand 1 (PD-L1) expression of 50% or higher who were treated with pembrolizumab as first-line therapy, the median PFS times of patients with PS 2 and 0-1 were 7.3 and 8.1 months, respectively. There was no significant difference in PFS between patients with PS 2 and 0-1 (P = .321). Although poor PS was significantly associated with worse outcomes in NSCLC patients treated with ICIs, pembrolizumab as a first-line treatment in NSCLC patients expressing high levels of PD-L1 could provide a clinical benefit, even in patients with PS 2.

Coordination Flexibility of the Rh(PXP) Complex to NH3, CO, and C2H4 (PXP = Diphosphine-Based Pincer Ligand; X = B, Al, and Ga): Theoretical Insight.

The recently synthesized rhodium-aluminum bimetallic complex Rh(PAlP) 1 (PAlP = pincer-type diphosphino-aluminyl ligand Al{[N(C6H4)]2NMe}[CH2P(iPr)2]2) containing a unique Rh-Al direct bond exhibits coordination flexibility because Rh and Al can play the role of coordination site for the substrate. DFT calculations of NH3, CO, and C2H4 adducts with 1 show that the Rh atom is favorable for all these substrate but the Al atom is as favorable as the Rh atom for NH3 and unfavorable for CO and C2H4. NH3 and CO prefer the coordination at the Rh-axial (Ax) site to the Rh-equatorial (Eq) site, but C2H4 prefers coordination at the Rh-Eq site to the Rh-Ax site. Consequently, two CO and C2H4 molecules coordinate with 1 at the Rh-Ax and Rh-Eq sites to afford trigonal bipyramidal complexes Rh(PAlP)(CO)2 and Rh(PAlP)(C2H4)2, which is consistent with the experimental observation of Rh(PAlP)(CO)2. Energy decomposition analysis reveals that an electrostatic term plays an important role for NH3 coordination with the Al atom of 1, because Al has a significantly large positive charge and NH3 has a much negatively charged N atom and exhibits a considerably negative electrostatic potential at the Al position. In B and Ga analogues Rh(PBP) 2 and Rh(PGaP) 3, B and Ga atoms are not good for CO and C2H4 like the Al atom in 1. NH3 adducts with 2 and 3 at the B and Ga sites are less stable than those adducts at the Rh-Ax site unlike the NH3 adduct with 1 at the Al site. This difference in the NH3 adduct between Rh(PAlP) and others (Rh(PBP) and Rh(PGaP)) arises from much less positive charges of B and Ga and a smaller atomic size of B than that of Al. These results indicate that the significantly large electropositive nature and appropriate atomic size of Al are responsible for the characteristic coordination flexibility of Rh(PAlP).

Characterization of Rh-Al Bond in Rh(PAlP) (PAlP = Pincer-type Diphosphino-Aluminyl Ligand) in Comparison with Rh(L)(PMe3)2 (L = AlMe2, Al(NMe2)2, BR2, SiR3, CH3, Cl, or OCH3): Theoretical Insight.

The unique Rh-Al bond in recently synthesized Rh(PAlP) 1 {PAlP = pincer-type diphosphino-aluminyl ligand Al[NCH2(P iPr2)]2(C6H4)2NMe} was investigated using the DFT method. Complex 1 has four doubly occupied nonbonding d orbitals on the Rh atom and one Rh d orbital largely participating in the Rh-Al bond which exhibits considerably large bonding overlap between Rh and Al atoms like in a covalent bond. Interestingly, Rhδ--Alδ+ polarization is observed in the bonding MO of 1, which is reverse to Rhδ+-Eδ- (E = coordinating atom) polarization found in a usual coordinate bond. This unusual polarization arises from the presence of the Al valence orbital at significantly higher energy than the Rh valence orbital energy. Characteristic features of 1 are further unveiled by comparing 1 with similar Rh complexes RhL(PMe3)2 (2 for L = AlMe2, 3 for L = Al(NMe2)2, 4 for L = BMe2, 5 for L = SiMe3, 6 for L = SiH3, 7 for L = CH3, 8 for L = OMe, and 9 for L = Cl). As expected, 7, 8, and 9 exhibit usual Rhδ+-Eδ- polarization (E = coordinating atom) in the Rh-E bonding MO. On the other hand, the reverse Rhδ--Eδ+ polarization is observed in the Rh-E bonding MOs of 2-5 like in 1, while the Rh-Si bond is polarized little in 6. These results are clearly understood in terms of the valence orbital energy of the ligand. Because the LUMO of 1 mainly consists of the Rh 4dσ, 5s, and 5p orbitals and the Al 3s and 3p orbitals, both Rh and Al atoms play the role of coordinating site for a substrate bearing a lone pair orbital. For instance, NH3 and pyridine coordinate to both Al and Rh atoms with considerably large binding energy. PAlP exhibits significantly strong trans influence, which is as strong as that of SiMe3 but moderately weaker than that of BMe2. The trans influence of these ligands is mainly determined by the valence orbital energy of the ligand and the covalent bond radius of the coordinating E atom.

Efficacy of afatinib treatment for lung adenocarcinoma harboring exon 18 delE709_T710insD mutation.

Exon 18 delE709_T710insD is an extremely rare mutation in epidermal growth factor receptor (EGFR) in non-small-cell lung cancer (NSCLC); the efficacy of EGFR tyrosine kinase inhibitors against this mutation remains unclear. In this case report, we report a case of NSCLC harboring EGFR exon 18 delE709_T710insD that was not detected by a commercially available assay, but was detected by a next-generation sequencing cancer panel. A 56-year old female patient with advanced NSCLC was diagnosed as EGFR-mutation-negative using the PNAClamp method. ALK rearrangement was also absent and she received cytotoxic chemotherapies. Clinical characteristics, including adenocarcinoma histology and no history of smoking, implied the presence of a driver mutation, so a next-generation-sequencing Oncomine® Cancer Research Panel was conducted in the patient's clinical course and the EGFR exon 18 delE709_T710insD mutation was detected. The patient started afatinib as sixth-line treatment and her pulmonary lesion significantly decreased in size. Afatinib was continued for 7 months until disease progressed.

Rhodium Complexes Bearing PAlP Pincer Ligands.

We report rhodium complexes bearing PAlP pincer ligands with an X-type aluminyl moiety. IR spectroscopy and single-crystal X-ray diffraction analysis of a carbonyl complex exhibit the considerable σ-donating ability of the aluminyl ligand, whose Lewis acidity is confirmed through coordination of pyridine to the aluminum center. The X-type PAlP-Rh complexes catalyze C2-selective monoalkylation of pyridine with alkenes.

A randomized, open-label phase II study on the preventive effect of goshajinkigan against peripheral neuropathy induced by paclitaxel-containing chemotherapy: The OLCSG2101 study protocol.

BACKGROUND: Paclitaxel (PTX) is an essential cytotoxic anticancer agent and a standard treatment regimen component for various malignant tumors, including advanced unresectable non-small cell lung cancer, thymic cancer, and primary unknown cancers. However, chemotherapy-induced peripheral neuropathy (CIPN) caused by PTX is a significant adverse event that may lead to chemotherapy discontinuation and deterioration of the quality of life (QOL). Although treatment modalities such as goshajinkigan (GJG), pregabalin, and duloxetine are empirically utilized for CIPN, there is no established evidence for an agent as a preventive measure. We designed a randomized phase II trial (OLCSG2101) to investigate whether prophylactic GJG administration can prevent the onset of CIPN induced by PTX. METHODS: This study was designed as a two-arm, prospective, randomized, multicenter phase II trial. The patients will be randomly assigned to either the GJG prophylaxis arm (Arm A) or the GJG non-prophylaxis arm (Arm B), using cancer type (lung cancer or not) and age (<70 years or not) as adjustment factors. A total of 66 patients (33 in each arm) will be enrolled. DISCUSSION: The results of this study may contribute to better management of CIPN, which can enable the continuation of chemotherapy and maintenance of the patient's QOL. ETHICS AND DISSEMINATION: Ethical approval was obtained from the certified review board of Okayama University (approval no. CRB21-005) on September 28, 2021. Results will be published in peer-reviewed journals and presented at national and international conferences. TRIAL REGISTRATION: Japan Registry of Clinical Trials (registration number jRCTs061210047).

Efficacy of immune checkpoint inhibitor monotherapy in elderly patients with non-small-cell lung cancer.

BACKGROUND: Limited information on anticancer therapy for super-elderly patients with non-small-cell lung cancer is available. Immune checkpoint inhibitors offer long-term survival to elderly patients aged ≥65 years with non-small-cell lung cancer. However, the efficacy and safety of immune checkpoint inhibitors in more elderly patients are not well understood. METHODS: We retrospectively evaluated the efficacy and safety of immune checkpoint inhibitors in patients aged ≥85 years with advanced non-small-cell lung cancer at nine centers using the Okayama Lung Cancer Study Group-Immunotherapy Database. RESULTS: Among 531 patients who received immune checkpoint inhibitors, 16 were aged ≥85 years (median, 86.5 years; range, 85-93 years). Many had high programmed death-ligand 1 expression and received pembrolizumab as first-line therapy. The objective response rate, median progression-free survival, and median survival time were 25% (95% confidence interval: 1-49), 2.8 months (95% confidence interval: 1.7-4.5), and not reached (95% confidence interval: 4.7-not reached), respectively. Moreover, the 4-year overall survival rate was 60.8% (95% confidence interval: 29.3-81.7), and a long-lasting effect of immune checkpoint inhibitors was observed even in patients aged ≥85 years. The incidence of immune-related and grade ≥3 immune-related adverse events was 32% and 6%, respectively. CONCLUSIONS: The effect and toxicity of immune checkpoint inhibitors for patients aged ≥85 years were acceptable. Immune checkpoint inhibitors may be a treatment option for patients aged ≥85 years.

CDK4/6 signaling attenuates the effect of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer.

Background: Epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletion and exon 21 L858R, are driver oncogenes of non-small cell lung cancer (NSCLC), with EGFR tyrosine kinase inhibitors (TKIs) being effective against EGFR-mutant NSCLC. However, the efficacy of EGFR-TKIs is transient and eventually leads to acquired resistance. Herein, we focused on the significance of cell cycle factors as a mechanism to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC before the emergence of acquired resistance. Methods: Using several EGFR-mutant cell lines, we investigated the significance of cell cycle factors to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC. Results: In several EGFR-mutant cell lines, certain cancer cells continued to proliferate without EGFR signaling, and the cell cycle regulator retinoblastoma protein (RB) was not completely dephosphorylated. Further inhibition of phosphorylated RB with cyclin-dependent kinase (CDK) 4/6 inhibitors, combined with the EGFR-TKI osimertinib, enhanced G0/G1 cell cycle accumulation and growth inhibition of the EGFR-mutant NSCLC in both in vitro and in vivo models. Furthermore, residual RB phosphorylation without EGFR signaling was maintained by extracellular signal-regulated kinase (ERK) signaling, and the ERK inhibition pathway showed further RB dephosphorylation. Conclusions: Our study demonstrated that the CDK4/6-RB signal axis, maintained by the MAPK pathway, attenuates the efficacy of EGFR-TKIs in EGFR-mutant NSCLC, and targeting CDK4/6 enhances this efficacy. Thus, combining CDK4/6 inhibitors and EGFR-TKI could be a novel treatment strategy for TKI-naïve EGFR-mutant NSCLC.

C2-Selective silylation of pyridines by a rhodium-aluminum complex.

We have developed a C2-selective mono-silylation of a variety of pyridines using a Rh-Al complex. Both the site- and mono-selectivity are controlled via the pyridine coordination to the Lewis-acidic Al center prior to the activation of the pyridine C(2)-H bond at the proximal Rh center. A reaction mechanism is proposed based on several mechanistic studies, including the isolation of a (2-pyridyl)silylrhodium intermediate.

The effects of antibiotics on the efficacy of immune checkpoint inhibitors in patients with non-small-cell lung cancer differ based on PD-L1 expression.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are essential for treatment of various malignancies, including non-small-cell lung cancer (NSCLC). Recently, several studies have shown that the gut microbiome plays an important role in ICI treatment of solid cancers, and antibiotic (ATB) use had a negative impact on the outcomes of ICI treatment via dysbiosis in the gut. However, whether this is applicable to NSCLC remains unclear. The impact of ATBs based on PD-L1 expression also remains unclear. METHODS: We retrospectively reviewed the medical records of patients with NSCLC who received ICI monotherapy (anti-PD-1 or anti-PD-L1 antibody) at nine institutions from December 2015 to May 2018. Outcomes with use of ATBs during the 2 months before or a month after initiation of ICI treatment, including progression-free survival (PFS) and overall survival (OS), were investigated using the Kaplan-Meier method. Multivariate analysis was also conducted using a Cox proportional hazards model. RESULTS: A total of 531 patients were included in this study, among whom 98 (18.5%) received ATBs before or after ICI treatment. ATB use was significantly associated with a shorter median OS (11.7 months in the ATB group vs. 16.1 months in the non-ATB group; p = 0.028), whereas the difference in PFS was not significant (3.5 months in both the groups; p = 0.287). We next investigated the association based on PD-L1 expression in the 265 patients for whom PD-L1 expression was determined. There was no significant difference in the median OS or PFS between patients with NSCLC and PD-L1 expression <50% receiving ATBs and those not receiving ATBs (PFS: 3.3 vs. 2.8 months, p = 0.88; OS: 9.5 vs. 17.1 months, p = 0.24). Conversely, patients with NSCLC and PD-L1 expression ≥50% receiving ATBs showed significantly shorter median PFS and OS (PFS: 4.2 vs. 9.4 months, p = 0.012; OS: 11.9 vs. 28.4 months, p = 0.011). The impact of ATBs in patients with NSCLC and PD-L1 expression ≥50% was more significant than that in the entire cohort. CONCLUSIONS: Our results indicate that the impact of ATB use on the efficacy of ICIs differed based on PD-L1 expression in patients with advanced NSCLC. A negative impact of ATB use was found in patients with NSCLC and PD-L1 expression ≥50% but not in those with PD-L1 expression <50%.

Significance of PD-L1 expression in the cytological samples of non-small cell lung cancer patients treated with immune checkpoint inhibitors.

OBJECTIVES: The programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) in tumor tissue samples is an established clinical biomarker for non-small cell lung cancer (NSCLC). However, the significance of PD-L1 expression in other types of samples has not been fully investigated. PATIENTS AND METHODS: We conducted a multicenter retrospective cohort study of advanced NSCLC patients who received ICI treatment during the clinical course and investigated the effects of ICIs according to PD-L1 expression in cytology samples, including cell block and endobronchial ultrasound-guided (EBUS) transbronchial needle aspiration (TBNA) samples. RESULTS: A total of 264 patients were included in this study: PD-L1 expression was determined in cell block or TBNA specimens in 55 patients, and in tissue samples in 209 patients. Among the former patients, the median progression-free survival (PFS) of those with a TPS for PD-L1 ≥ 50% was significantly longer compared to that of those with a TPS < 50% (6.5 vs. 1.9 months, respectively, p = 0.008). When the cutoff value was set at 1%, the median PFS was 4.2 months in patients with a TPS ≥ 1% and 1.5 months in patients with a TPS < 1% (p < 0.001). CONCLUSION: PD-L1 expression determined using cytology specimens predicts the efficacy of ICIs.