Yasuhiro Koh

11541 Background: PD-L1 expression on tumor tissue is associated with response to PD-1 blockade in NSCLC. Here, we conducted a serial evaluation of PD-1-expressing circulating tumor cells (CTCs) as a potential real-time diagnostic modality in NSCLC patients treated with nivolumab. Methods: Advanced NSCLC patients after failure of at least one prior chemotherapy regimen received nivolumab monotherapy (3mg/kg, q2W) until progressive disease (PD) or unacceptable toxicity. Peripheral whole blood (3 mL) was collected for CTC evaluation at baseline and at week 4. CTCs were detected using microcavity array system (Hitachi Chemical Co., Ltd, Chikusei, Japan). PD-L1 expression was immunohistochemically examined on both tumor tissues and CTCs. This study was registered at UMIN (ID: 000024414). Results: Thirty patients were registered in the study between January 2016 and September 2016 at Wakayama Medical University Hospital and 29 were included in the analysis. Demographics of the patients were as follows: median age 70 (range, 49 to 86); male 73 %; stage IV, 100 %; squamous/non-squamous, 27/73 %. At baseline, CTCs were detected in all patients (median, 15; range, 1 to 90) and PD-L1-expressing CTCs were detected in 87% of patients. Tumor proportion score (TPS) of PD-L1 expression on CTCs ranged from 6% to 100%, indicating intrapatient heterogeneity. Matched tumor tissues were available from 14 patients and 7 showed the PD-L1 TPS ≥ 50%. No positive correlation was observed on PD-L1 expression between tumor tissues and CTCs based on TPS (R2 = 0.0035). Overall response rate was 25% (7/29), and disease control rate was 54% (15/29). Total CTC count was significantly decreased after nivolumab treatment at week 4 (p < 0.05), but no significant change was observed in PD-L1 TPS on CTC. Patients harboring CTCs with PD-L1 TPS 50% or more at baseline were significantly more likely to achieve non-PD than those harboring CTCs with TPS less than 50% (p < 0.05). Conclusions: This is the first report on a serial monitoring of PD-L1 expression on CTCs in patients treated with nivolumab. PD-L1-expressing CTCs are suggested to hold potential for predicting clinical benefit. Clinical trial information: 000024414.

9027 Background: Liquid biopsy has been approved as an alternative method to detect clinically relevant EGFR mutations in NSCLC. However, it is unknown whether the early assessment of molecular response in plasma could be a surrogate of clinical response and/or longer efficacy. Here, we conducted a prospective, multi-institutional study of liquid biopsy in EGFRmutated NSCLC patients (WJOG 8114LTR). Methods: Chemotherapy naïve, advanced NSCLC patients with EGFR-sensitizing mutation received afatinib monotherapy (40 mg/body) until progressive disease (PD) or unacceptable toxicity. Plasma DNA was obtained from patients at baseline, weeks 2, 4, 8, 12, 24, 48, and at PD. Three types of clinically relevant EGFRmutations (exon 19 deletion, exon 20 T790M and exon 21 L858R) will be analyzed using plasma DNA with multiplexed, pico-droplet digital PCR assay (RainDrop system, RainDance Technologies, Billerica, MA). Complete molecular response (CMR) was defined as mutant allele event/frequency of exon 19 deletion or exon 21 L858R below the cutoff for the positivity by digital PCR in plasma. This study was registered at UMIN (ID: 000015847). Results: Fifty-seven patients were registered in the study. Efficacy of afatinib was comparable to previous reports (overall response rate: 78.6%, and median progression-free survival (mPFS): 14.2 months). At baseline, 62.5% of patients were positive for EGFR mutation in plasma. Plasma positive patients had slightly shorter PFS than plasma negative patients, but not significant (p = 0.24, log-rank). Among those who were positive at baseline, CMR was achieved in 60.6% of patients at two weeks, and 87.5% at four weeks, respectively. Patients with CMR at two weeks had significantly longer PFS than those without one (13.6 versus 7.5 months, p = 0.0001). Patients with CMR at four weeks also demonstrated longer PFS than those without one (13.6 versus 5.1 months, p < 0.0001). Among patients who achieved CMR by week four, time to achieve CMR did not affect PFS ( p= 0.59). Conclusions: This is the first report on the predictive impact of early CMR in plasma for longer therapeutic efficacy of afatinib in EGFR mutated NSCLC patients. Clinical trial information: 000015847.

The majority of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation eventually develop resistance to EGFR tyrosine kinase inhibitors (TKIs). Minimal information exists regarding genetic alterations in rebiopsy samples from Asian NSCLC patients who develop acquired resistance to EGFR-TKIs. We retrospectively reviewed the medical records of patients with NSCLC harboring EGFR mutations who had undergone rebiopsies after developing acquired resistance to EGFR-TKIs. We analyzed 27 practicable samples using a tumor genotyping panel to assess 23 hot-spot sites of genetic alterations in nine genes (EGFR, KRAS, BRAF, PIK3CA, NRAS, MEK1, AKT1, PTEN, and HER2), gene copy number of EGFR, MET, PIK3CA, FGFR1, and FGFR2, and ALK, ROS1, and RET fusions. Additionally, 34 samples were analyzed by commercially available EGFR mutation tests. Sixty-one patients underwent rebiopsy. Twenty-seven samples were analyzed using our tumor genotyping panel, and 34 samples were analyzed for EGFR mutations only by commercial clinical laboratories. Twenty-one patients (34%) had EGFR T790M mutation. Using our tumor genotyping panel, MET gene copy number gain was observed in two of 27 (7%) samples. Twenty patients received continuous treatment with EGFR-TKIs even after disease progression, and 11 of these patients had T790M mutation in rebiopsy samples. In contrast, only 10 of 41 patients who finished EGFR-TKI treatment at disease progression had T790M mutation. The frequency of T790M mutation in patients who received continuous treatment with EGFR-TKIs after disease progression was significantly higher than that in patients who finished EGFR-TKI treatment at disease progression (55% versus 24%, p = 0.018). The frequency of T790M mutation in this study was lower than that in previous reports examining western patients. These results suggest that continuous treatment with EGFR-TKI after disease progression may enhance the frequency of EGFR T790M mutation in rebiopsy samples.

E23036 Background: Immune-checkpoint blockage with anti-PD-1 antibodies is effective against human malignancies including lung cancer. Although the expression of PD-L1 on tumor cells is expected as a predictive biomarker, detection of PD-L1 expression level on tissues remains challenging due to its dynamic and unstable expression. Here, we isolated circulating tumor cells (CTCs) and then evaluated the expression of PD-L1 on them in patients with advanced non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Methods: Immuno-staining for PD-L1 was established using NSCLC cell lines H820, H441, A549 and H23, spiked in the peripheral blood obtained from healthy donors. For clinical evaluation, 3 ml of peripheral whole blood was collected from 41 advanced lung cancer patients prior to the initiation of chemotherapy. Cells were captured and stained by using MCA system (Hitachi Chemical Co., Ltd). CTCs were defined as those positive for DAPI and cytokeratin (CK) and negative for CD45. Results: Characteristics of 41 lung cancer patients enrolled in clinical study were as follows: median age 70 (range, 39 to 86); male 66 %; stage II/III/IV, 2/7/91 %; NSCLC/SCLC, 80/20 %. More than 5 CTCs were detected in 32 patients (median 21.5; range, 7 to 58), and PD-L1-positive CTCs were detected in 22 patients (median 4; range, 1 to 15). All the patients bearing PD-L1-positive CTCs also had PD-L1-negative CTCs concurrently. We found a total of 49 CTC clusters from 24 patients and most of clusters contained PD-L1-positive CTCs (44/49 clusters, 90%). On top of that, CTCs forming clusters were more likely to be PD-L1-positive than those detected as a single CTC (28/80, 35% versus 104/769, 14%, respectively. p = 0.001). We also found that CTC-interacting white blood cells were more intensively bound with clustered CTCs than with single CTCs (15/77, 19% versus 55/598, 9%, respectively. p = 0.016). Conclusions: Our data suggest that PD-L1 expression on CTCs have diverse intrapatient heterogeneity in advanced lung cancer. Further investigation is warranted to address its clinical significance in response to PD-1/PD-L1 blockade and to clarify the biology of the aggregated CTCs and those interacting with white blood cells.

Despite considerable recent progress in the treatment of lung adenocarcinoma, there has been little progress in the development of efficacious molecular targeted therapies for squamous cell lung cancer. In addition to the recent comprehensive genome-wide characterization of squamous cell lung cancer, it is also important to genotype this form of cancer. We therefore conducted the Shizuoka Lung Cancer Mutation Study to analyze driver mutations in patients with thoracic malignancies. Here we report the results of genotyping in patients with squamous cell lung cancer. Based on the biobanking system, in conjunction with the clinic and pathology lab, we developed a genotyping panel designed to assess 24 mutations in 10 genes (EGFR, KRAS, BRAF, PIK3CA, NRAS, MEK1, AKT1, PTEN, HER2 and DDR2), EGFR, MET, PIK3CA, FGFR1 and FGFR2 copy numbers, and EML4-ALK and ROS1 translocations, using pyrosequencing plus capillary electrophoresis, quantitative polymerase chain reaction (PCR) and reverse-transcription PCR, respectively. A total of 129 patients with squamous cell lung cancer and adenosquamous carcinoma were enrolled in this study between July 2011 and November 2012. We detected genetic alterations in 40% of all cases. Gene alterations included: EGFR mutations, 6%; KRAS mutations, 4%; PIK3CA mutations, 13%; NRAS mutations, 1%; KIF5b-RET fusion gene, 1%; EGFR copy number gain, 5%; PIK3CA copy number gain, 15%; and FGFR1 copy number gain, 5%. Twelve patients (9%) harbored simultaneous genetic alterations. Genetic alterations were detected more frequently in surgically-resected, snap-frozen samples than in formalin-fixed, paraffin-embedded samples (50% vs. 29%). In addition, patients aged ≤70 years old and never-smokers showed high frequencies of genetic alterations. This study represents one of the largest prospective tumor-genotyping studies to be performed in Asian patients with squamous cell lung cancer. These results suggest that incorporation of genetic profiling into lung cancer clinical practice may facilitate the administration of personalized cancer treatments in patients with squamous cell lung cancer.

Background/Aim: The acquisition of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) remains a major challenge in lung cancer medicine. We sought to identify biomarkers for the early detection of resistance to TKIs. Materials and Methods: Capillary electrophoresis time-of-flight mass spectrometry analysis was performed to identify the metabolic signatures associated with erlotinib resistance in erlotinib-resistant PC-9ER NSCLC cells established from the EGFR-mutant NSCLC cell line PC-9. Results: PC-9ER cells showed metabolic signatures indicative of enhanced glutamine metabolism. Copy number gains in v-myc avian myelocytomatosis viral oncogene homolog (MYC), glutathione-S-transferase theta 2 (GSTT2), gamma-glutamyltransferase 1 (GGT1), and GGT5 were also detected, suggesting that amplification of these genes confers glutamine addiction in PC-9ER cells. Conclusion: Enhanced glutamine metabolism may be a surrogate marker that can be used to predict the likelihood of patients to respond to EGFR-TKIs.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) are effective for non-small cell lung cancers (NSCLC) with EGFR-activating mutations. However, most responders develop resistance. Efatutazone, a novel peroxisome proliferator-activated receptor gamma (PPAR) agonist, is currently under clinical evaluation; it has antiproliferative effects and induces cellular morphological changes and differentiation. The present study investigated the effects of efatutazone in EGFR-TKI-resistant NSCLC cells, while focusing on cell motility. The PC-9-derived NSCLC cell lines PC-9ER and PC-9ZD, resistant to EGFR-TKI due to v-crk avian sarcoma virus CT10 oncogene homolog-like (CRKL) amplification-induced phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT) activation and an EGFR T790M mutation, respectively, were used. These cells exhibit enhanced cell motility due to transforming growth factor (TGF-)/Smad2 family member 2 (Smad2) pathway activation. Efatutazone had no growth-inhibitory effect on the tested cells but inhibited the motility of EGFR-TKI-resistant cells in wound closure and transwell assays. Efatutazone plus erlotinib treatment provided greater inhibition of PC-9ER cell migration than efatutazone or erlotinib alone. Efatutazone suppressed increased TGF-2 secretion from both cell lines (shown by ELISA) and downregulation of TGF-2 transcription (observed by quantitative RT-PCR). Immunoblot analysis and luciferase assays revealed that efatutazone suppressed Smad2 phosphorylation and its transcriptional activity. These results suggest that efatutazone inhibits cell motility by antagonizing the TGF-/Smad2 pathway and effectively prevents metastasis in NSCLC patients with acquired resistance to EGFR-TKI regardless of the resistance mechanism.

BACKGROUND: Integration of mutational profiling to identify driver genetic alterations in a clinical setting is necessary to facilitate personalized lung cancer medicine. A tumor genotyping panel was developed and the Shizuoka Lung Cancer Mutation Study was initiated as a prospective tumor genotyping study. This study reports the frequency of driver genetic alterations in Japanese lung adenocarcinoma patients, and clinicopathologic correlations with each genotype.METHODS: Between July 2011 and January 2013, 411 lung adenocarcinoma patients admitted to the Shizuoka Cancer Center were included in this study with their written informed consent. Surgically resected tissues, tumor biopsies, and/or body cavity fluids were collected and tested for 23 hotspot sites of driver mutations in 9 genes (EGFR, KRAS, BRAF, PIK3CA, NRAS, MEK1, AKT1, PTEN, and HER2), gene amplifications in 5 genes (EGFR, MET, PIK3CA, FGFR1, and FGFR2), and ALK, ROS1, and RET fusions.RESULTS: Genetic alterations were detected in 54.3% (223 of 411) of all patients. The most common genetic alterations detected in this study were EGFR mutations (35.0%) followed by KRAS mutations (8.5%) and ALK fusions (5.0%). Concurrent genetic alterations were detected in 22 patients (5.4%), and EGFR mutations were observed in 16 patients as the most common partner for concurrent genetic alteration. Significantly more concurrent genetic alterations were observed in older patients.CONCLUSIONS: This is one of the largest reports of a prospective tumor genotyping study on Japanese patients with adenocarcinoma. These data suggest that mutational profiling data using a multimutational testing platform would be valuable for expanding the range of molecular‐targeted therapeutics in lung cancer. Cancer 2014;120:1471–1481. © 2014 American Cancer Society.