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Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned coprimary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. In a randomized, open-label, phase III NEJ009 study, gefitinib plus chemotherapy significantly improved progression-free survival (PFS) and overall survival (OS) compared with gefitinib-alone in patients with untreated non–small-cell lung cancer harboring mutations in epidermal growth factor receptor. Herein, we report the updated survival outcome and long-term tolerability. Patients were randomly assigned to gefitinib (gefitinib 250 mg orally, once daily) and gefitinib combined with carboplatin plus pemetrexed (GCP in a 3-week cycle for six cycles followed by concurrent gefitinib and pemetrexed maintenance) groups. At the data cutoff (May 22, 2020), GCP demonstrated significantly better PFS2 (hazard ratio, 0.77; 95% CI, 0.62 to 0.97; P = .027) than gefitinib. However, the updated median OS was 38.5 months (95% CI, 31.1 to 47.1) and 49.0 months (95% CI, 41.8 to 56.7) in the gefitinib and GCP groups, respectively (hazard ratio, 0.82; 95% CI, 0.64 to 1.06; P = .127). The OS in both groups was similar for the overall patient population. No severe adverse events occurred since the first report. This updated analysis revealed that the GCP regimen improved PFS and PFS2 with an acceptable safety profile compared with gefitinib-alone. GCP is more efficient than gefitinib monotherapy as a first-line treatment for non–small-cell lung cancer with epidermal growth factor receptor mutations.

9030 Background: Immuno-checkpoint inhibitor (ICI) monotherapy is a standard second-line treatment for non-small-cell lung cancer (NSCLC). Addition of a cytotoxic agent to ICI may enhance the benefits. Methods: This multi-institutional open-label randomized phase II/III study compared the arm A consisting of nivolumab (NIV) monotherapy and arm B consisting of NIV + docetaxel (DTX) for patients with previously treated ICI-naïve NSCLC, prestratified by PS/histological types/sex/driver-mutations. The primary endpoint was superiority of arm B in OS in the phase III part. Assuming a HR of 0.75 for OS with the estimated mOS of arm A/B as 10.5/14.0 mo, a total 350 patients would be required to provide 80% power at a one-sided α of significance being 0.05. It was started at Nov. 2017, however, the patients’ accrual was discontinued due to the approval of ICI in the first-line setting in late 2018. Eventually, a total of 131 patients were enrolled for analysis. Results: 128 patients (64 in each arm) were eligible and included in full analysis set (FAS), and the patients’ demographics were well-balanced in each arm. The mOS was 14.7 mo (95%CI, 11.4-18.7) in arm A, and 23.1 mo (95%CI, 16.7-NR) in arm B. The HR of OS was 0.63 (90%CI, 0.42-0.95; p = 0.0310). The mPFS was 3.1 mo (95%CI, 2.0-3.9) and 6.7 mo (95%CI, 3.8-9.4) in arm A and B, respectively. The HR for PFS was 0.58 (95%CI, 0.39-0.88; p = 0.0095). The ORR was 14.0% (95%CI, 6.3-25.8) in arm A, and 41.8% (95%CI, 28.7-55.9) in arm B, with a statistical significance (p = 0.0014). Subgroup analyses for OS disclosed that the HRs favored arm B over arm A across all prespecified subgroups. The mOS of EGFR-mutant subgroup also showed better tendency in arm B than A (11.0 mo in arm A; 95%CI, 3.5-14.0; vs 20.6 mo in B; 95%CI, 5.8-NR; HR 0.45; 95%CI, 0.17-1.17). The hematological toxicity and gastrointestinal adverse events were more common in arm B than in A. Six (9.4%) in arm A and 25 patients (39.1%) in arm B discontinued protocol treatment due to adverse events. Overall, two treatment-related deaths were observed; one from pneumonitis in arm A, and one from myocarditis in arm B. Conclusions: Although the resulting statistical power was limited because of reduced sample size, the addition of DTX to NIV in the second-line NSCLC therapy significantly improved OS, PFS, and ORR, despite slightly elevated risk of toxicity. This is the first randomized clinical trial that confirmed significant survival benefit of ICI + chemotherapy over ICI alone in any cancer type. Clinical trial information: UMIN000021813.

9097 Background: Osimertinib (OSI), a third-generation EGFR-tyrosine kinase inhibitor (EGFR-TKI), is now a standard treatment for previously untreated EGFR-mutated (EGFRm) advanced non-small cell lung cancer (NSCLC). In the two randomized phase 3 studies, progression-free survival (PFS) and overall survival were statistically significant and clinically longer with gefitinib and platinum-based chemotherapy compared with gefitinib monotherapy. Based on these data, we have planned this phase 2 study to evaluate the safety and efficacy of OSI combined with platinum-based chemotherapy. Patients and Methods: This multicenter phase 2 study enrolled patients (pts) with clinical stage IIIB, IIIC, IVA, IVB or postoperative recurrent, previously untreated EGFRm NSCLC. Pts received oral OSI 80mg once daily (QD), with either cisplatin 75mg/m2 (arm A) or carboplatin [area under the curve (AUC) = 5, arm B], plus pemetrexed (PEM) 500 mg/ m2 every 3 weeks (Q3W) for four cycles. In both arms, maintenance was OSI 80mg QD with PEM 500 mg/ m2 Q3W until disease progression or discontinuation. The co-primary endpoints were the safety and the objective response rate (ORR), and the secondary endpoints included the complete response rate (CRR), disease control rate (DCR), and PFS. Results: From July 2019 to February 2020, 67 pts (34 pts in Arm A; 33 pts in arm B) were enrolled: median (range) age 67 (26-75) years; 43 (64.2%) female; 46 (68.7%) ECOG PS 0; 66 (98.5%) adenocarcinoma; 31 (46.3%) EGFR exon19 deletion, 35 (52.2) L858R, and 1 (1.5%) both. One pt did not comply with the eligibility criteria and was excluded from the efficacy analysis. At data cut off (August 31, 2021), 27 (40.3%) pts [15 (44.1%) in arm A and 12 (36.4%) in arm B] had discontinued the protocol treatment, including 9 (13.4%) pts [5 (14.7%) in arm A and 4 (12.1%) in arm B] due to the adverse event (AE). The rate of grade (G) ≥ 3 AEs were 91.0% (88.2% in arm A and 93.9% in arm B). For the safety, neutropenia, anemia and thromobocytopenia were numerically higher in arm B and the rates of G ≥ 3 were 29.4%/60.6%, 14.7%/27.3% and 0.0%/42.4% in arm A/B, respectively. G ≥ 3 QTc interval prolonged and G ≥ 2 anorexia were observed in 14.7%/21.2% and 26.5%/24.2%, respectively. For the efficacy, the ORR was 90.9% [95% confidence interval (CI); 84.0-97.8%]. The CRR/DCR were 3.0%/97.0% (95% CI; 0.0-7.2%/92.8%-100.0%), respectively. At a median follow-up time of 21.4 months (range, 18.2-25.7), median PFS was not reached in both A and B, with an estimated 12-/24-months PFS rate of 90.4%/70.0%. Conclusions: OSI combined with platinum-based chemotherapy for previously untreated EGFRm advanced NSCLC showed the excellent efficacy with tolerable toxicity. This combination treatment is highly promising and should be validated in the phase 3 study. Clinical trial information: jRCTs031180226.

9103 Background: Osimertinib is a standard drug for first-line treatment of patients with advanced non–small cell lung cancer (NSCLC) harboring EGFR mutations (mt). While tumor mutational burden (TMB)-high and co-occurring genetic alterations (alt) have been reported to be negatively associated with the efficacy of other EGFR-TKIs, the impact of co-occurring genetic alt with EGFR major mt on the efficacy of osimertinib remains unclear. Methods: In a multi-institutional genomic screening project (LC-SCRUM-Asia), we have analyzed lung cancer patients for genomic alt by a targeted next-generation sequencing (NGS) system, Oncomine Comprehensive Assay and Genexus/OPA. We retrospectively evaluated the association between the genomic profile and efficacy of first-line osimertinib for EGFR-mutated NSCLC based on the LC-SCRUM-Asia database. Results: Between March 2015 and January 2022, 12,705 NSCLC patients were enrolled in the LC-SCRUM-Asia database, and EGFR mt was detected in 2,232 patients. Of these, 324 patients, including 171 with ex19del (53%) and 153 with L858R (47%), received first-line treatment with osimertinib. The patient characteristics were as follows: median age, 69 years (range 31-97); females, 64%; never-smokers, 57%; adenocarcinoma, 97%; and performance status 0-1, 99%. The frequency of compound EGFR mt and TMB were higher in the L858R (LR) group than in the ex19del (Ex19) group (compound mt (%), 12 vs. 4; mean TMB (mt/Mb), 3.4 vs. 2.5). There were no differences in the frequencies of other co-occurring genetic alt between the two groups. Higher TMB, alt of genes encoding receptor tyrosine kinase (RTK), including FGFR1, RET, MET etc., and amp of cell-cycle related genes were significantly associated with shorter progression-free survival (PFS) in the entire group (median PFS: TMB > 3 vs. ≤3 mt/Mb = 11.4 vs. 17.1 months; p = 0.023; RTK gene alt+ vs. alt- = 9.7 vs. 15.2 months; p = 0.014; cell-cycle gene amp+ vs. amp- = 10.6 vs. 15.6 months, p = 0.001). EGFR subgroup analysis showed that a higher TMB was significantly associated with a shorter PFS in the LR group (> 3 vs. ≤3 mt/Mb = 10.0 vs. 17.1 months, p < 0.001), but not in the Ex19 group. On the other hand, alt of genes encoding RTK and amp of cell-cycle related genes were significantly associated with a shorter PFS in the Ex19 group (RTK gene alt+ vs. alt- = 8.4 vs. 17.8 months, p = 0.008; cell-cycle gene amp+ vs. amp- = 10.6 vs. 17.5 months, p = 0.003), but not in the LR group. Multivariate analysis identified RTK gene alt in the Ex19 group and higher TMB in the LR group as being independently associated with a shorter PFS. Conclusions: First-line osimertinib treatment was less effective in NSCLC patients harboring Ex19 with other RTK gene alt or LR with a higher TMB, indicating that co-occurring genetic alt affecting the efficacy of osimertinib differ between NSCLC patients harboring Ex19 and LR.

e21177 Background: The significance of micro-pretreatment EGFR T790M mutation on EGFR-tyrosine kinase inhibitor (TKI) efficacy in patients with non-small cell lung cancer (NSCLC) remains uncertain. In addition, there has been no method to examine the micro-T790M mutation after excluding formalin-fixed and paraffin-embedded (FFPE)-derived artificial mutations. Therefore, we used a novel method to examine the variant allele frequency (VAF) of T790M mutation in the FFPE samples after excluding the artificial mutations. Subsequently, we retrospectively investigated the association between micro-T790M mutations and time to treatment failure (TTF) in patients treated with 1st, 2nd, or 3rd generation (1G, 2G, 3G) EGFR-TKIs. Methods: We enrolled patients with NSCLC who harbored EGFR exon 19 deletion (Del19) or L858R without T790M mutation using conventional methods. Patients who received 1G or 2G EGFR-TKIs until June 2018 or 3G EGFR-TKI until June 2019 from 31 institutions were included. Droplet digital PCR was performed using pretreatment FFPE tumor samples. We defined cases as micro-T790M positive when the VAF of T790M was higher than that of F795F, owing to the FFPE-derived artificial mutations. The ratio of micro-T790M mutation was calculated as follows: {(VAF of T790M) – (VAF of F795F)} /VAF of (Del19 or L858R). The lowest value was set as 0. Results: A total of 110, 102, and 103 patients received 1G, 2G, and 3G EGFR-TKIs, respectively. Of these patients, 48.1%, 47.0%, and 47.6% were classified as micro-T790M positive, respectively. The ratios of micro-T790M mutation, represented as median (%) (interquartile range), in 1G, 2G, and 3G EGFR-TKI groups were 0.27 (0.12-0.87), 0.28 (0.13-0.47), and 0.42 (0.20-0.68), respectively. The VAF of T790M or F795F in all patients, represented as median (%) (interquartile range), was 0.26 (0.19-0.35) or 0.25 (0.19-0.33), respectively. The TTF was not significantly different between the T790M-positive and negative groups in analysis based on each generation TKIs. In the Del19 group, the TTF of the 1G EGFR-TKI was significantly shorter, while that of the 3G EGFR-TKI was significantly longer in the T790M-positive group than in the negative group ( p= 0.02, 0.04, respectively). In the T790M-positive group, the TTF of the 2G or 3G EGFR-TKI group was significantly longer than that of the 1G EGFR-TKI group ( p= 0.04, 0.01, respectively). This result was observed in the Del19 group but not in the L858 group. Furthermore, TTF did not significantly differ between the 1G, 2G, and 3G EGFR-TKIs in the T790M-negative group. Conclusions: This study showed that micro- EGFR T790M mutations influence the EGFR-TKI efficacy. Detection of micro-T790M mutations will facilitate selection of the optimal EGFR-TKI for patients with EGFR mutated NSCLC.

8567 Background: Chemo-immunotherapy is the standard 1st-line therapy for patients with extensive-stage small cell lung cancer (ES-SCLC). Prospective data about underrepresented populations outside the clinical trial such as elderly or poor risk has not been revealed. Methods: We conducted a 32-hospitals prospective cohort study of consecutive patients with ES-SCLC who received carboplatin and etoposide with atezolizumab as 1st-line therapy between September 2019 and September 2020. The primary outcome was 6-months progression-free survival (PFS) probability of all patients. The secondary outcomes were overall survival (OS), PFS, time to treatment failure, objective response rate, safety, and differences in efficacy and safety depending on whether or not the key eligible study criteria of previous trials are met. Results: In total, 207 patients with ES-SCLC were analyzed. The median age was 72 years, and 64 patients (31%) were elderly (≥75 years). Most patients (89%) had a performance status (PS) of 0 or 1. As a result, 132 (64%) was categorized as eligible patients. The 6-months PFS probability of all patients was 38.8 % (95%CI:32.4-45.7%). Between eligible and ineligible patients, there was significant difference of patients who attained disease control (93% versus 77%, p = 0.002). Median PFS was significantly longer in eligible patients than ineligible patients (5.1 vs. 4.7 months; P =.03, HR 0.72 (95% CI 0.53–0.97)), and median OS was longer in eligible patients than ineligible patients, without any significant difference (15.8 vs. 13.1 months; P =.10, HR 0.73 (95% CI 0.51–1.07)). Survival analysis identified a PS score of 0-1 (HR: 0.60, 95% CI: 0.39-0.97, p = 0.03) as a significant predictor of better PFS, while PS score of 0-1 (HR: 0.51, 95% CI: 0.31-0.89, p = 0.01) and younger patients ( < 75 years) (HR: 0.66, 95% CI: 0.45-0.97, p = 0.03) as significant-good predictor of OS. The rate of severe AEs was higher in ineligible patients than in eligible (39% vs. 27%, respectively; p = 0.07), although the difference was not significant. Older age was significantly associated with severe AEs (p = 0.049). Conclusions: The real-world efficacy of chemo-immunotherapy for ES-SCLC was similar to that of pivotal clinical trials. However, trial-ineligible patients with ES-SCLC had poor treatment outcome and the higher rates of severe adverse events in this prospective cohort study. Our study suggests that positive results among the trial eligible patients may not translate to ineligible patients. Clinical trial information: UMIN000038064.

9097 Background: TMB estimation using targeted NGS panels is widely performed in clinical practice. The objective of this study was to determine the optimal NGS panel for estimating TMB and to evaluate its clinical implications for NSCLC. Methods: Two NGS panels, Oncomine Tumor Mutation Load Assay (OMLA) and FoundationOne (F1), were compared to select the most accurate TMB prediction panel. From February 2017 to May 2018, 350 lung cancer patients were analyzed by whole-exome sequencing (WES), and the concordance rate of OMLA and F1 to WES was examined. In addition, its clinical utility as a biomarker for immune checkpoint inhibitors (ICIs) was evaluated in our international genome screening network (LC-SCRUM-Asia). From June 2019 to December 2020, 3141 patients with NSCLC from 185 institutions were enrolled, and genomic analysis was successful. The clinico-genomic database of LC-SCRUM-Asia was used for this analysis. Results: The linear correlation with WES was 0.80 for OMLA and 0.78 for F1. This indicated that OMLA was more strongly correlated with WES. The cutoff value of F1 was 10 mut/Mb, which corresponded to 9 mut/Mb (OMLA) and 194 mutations (WES). The sensitivity of the OMLA for WES was 79%, and the specificity was 85%. Meanwhile, the sensitivity of the F1 was 74%, and the specificity was 80%. OMLA more accurately predicted TMB, and its clinical utility was evaluated. 3141 NSCLC patients, consisting of 2282 adenocarcinomas, 593 squamous cell carcinomas, and 266 others, were analyzed for TMB, estimated using OMLA. The median number of mutations was 4.2 mut/Mb (range, 0-718.4/Mb). High TMB (≥9 mut/Mb) was observed in 17.2% (393/2282) of adenocarcinoma cases and 25.8% (153/593) in squamous cell carcinoma cases. 778 patients were treated with ICI or ICI plus chemotherapy as the first-line treatment. Patients’ characteristics were as follows: male/female; 595/183, median age (range); 67 (25-90), stage II/III/VI/recurrence; 11/90/649/28, TMB high/low; 177/601, ICI/ICI plus chemotherapy; 114/664. The progression-free survival (PFS) was significantly longer in patients with high TMB than in those with low TMB (median PFS, 7.5 vs. 5.9 months, p = 0.0314). The overall survival (OS) was significantly longer in patients with high TMB than in those with low TMB (median OS, 27.4 vs. 20.4 months, p = 0.006). Conclusions: The TMB estimated by OMLA correlated more strongly with the WES-derived TMB comparing with F1. TMB estimated by OMLA was correlated with PFS and OS in NSCLC patients treated with ICIs. Prospective clinical trials are needed to determine whether TMB estimated by OMLA is a biomarker for ICI.

9054 Background: RAS ( KRAS, NRAS and HRAS) is a targetable oncogene family in several cancers, including NSCLC, and the clinical development of various RAS-targeted therapies are ongoing. However, the clinical relevance of uncommon RAS mutations, such as NRAS and HRAS mutations, in NSCLC patients (pts) remains unclear. Methods: In a large-scale genomic screening project (LC-SCRUM-Asia), we have prospectively analyzed lung cancer pts for genomic alterations by a targeted next-generation sequencing (NGS) system, Oncomine Comprehensive Assay. We evaluated clinico-pathological and genomic characteristics in NRAS- or HRAS-mutated NSCLC pts comparing with those in KRAS-mutated pts based on the LC-SCRUM-Asia database. Results: Since March 2015 to December 2020, 9131 NSCLC pts were enrolled in the LC-SCRUM-Asia, and 8374 of them (92%) were successfully analyzed by NGS. The RAS mutation frequencies were 1134 KRAS (14%), 50 NRAS (0.6%), and 15 HRAS (0.2%). The most frequent variant of NRAS and HRAS mutations was Q61X (78%) and G13X (80%), respectively, whereas that of KRAS was G12X (84%). Patient characteristics were summarized in Table. Male was significantly frequent in NRAS- than in KRAS-group (p=0.03), and smokers were frequent in all the three groups (overall, 79%). The majority of NRAS (70%) and KRAS mutations (89%) were detected in adenocarcinoma (Ad), whereas 60% of HRAS mutations were in squamous cell carcinoma (Sq). Tumor mutation burden (TMB) was significantly higher in NRAS-mutated tumors than in KRAS-mutated tumors (p=0.03). Concomitant TP53 mutations were significantly frequent in HRAS-mutated pts than in KRAS-mutated pts (53% vs. 30%, p=0.05), and STK11 mutations were also tended to be frequent in HRAS-mutated pts than in KRAS-mutated pts (20 vs. 7%, p=0.10). Therapeutic efficacy of PD-1/PD-L1 inhibitors was not different among the three groups in the current follow-up data, but HRAS-mutated tumors did not respond to PD-1/PD-L1 inhibitors (response rate, 0%; median PFS, 1.6 months). Conclusions: NRAS- or HRAS-mutated NSCLCs were different from KRAS-mutated NSCLCs in clinico-pathological and genomic profiles. In particular, the immunotherapies were not effective for HRAS-mutated NSCLCs.[Table: see text]

9094 Background: A variety of oncogene drivers have been identified in NSCLC and molecularly-stratified precision medicine has led to improved survival in advanced NSCLC. Next-generation sequencing (NGS)-based testing is utilized to detect actionable gene alterations; however, the TAT of NGS is often too long to translate into clinical decision making. Thus, rapid multi-gene testing alternatives are needed. Methods: A lung cancer genomic screening project (LC-SCRUM-Asia) capturing clinical outcome was established in 2013 to identify patients with oncogene drivers and to support the development of novel targeted therapies. Since February 2013 to May 2019 (LC-SCRUM-Asia 1st-phase), single gene testing and/or a targeted NGS assay, Oncomine Comprehensive Assay (OCA), were used for the genomic screening. Since June 2019 to December 2020 (2nd-phase), a multi-gene PCR assay (Amoy 9-in-1 test) and a rapid NGS assay (Genexus/Oncomine Precision Assay [OPA]) were also implemented as rapid multi-gene testing. Results: A total of 10667 Japanese NSCLC patients, including 6826 in the 1st-phase and 3841 in the 2nd-phase, were enrolled in the LC-SCRUM-Asia. Success rate for OCA: 93%, for 9-in-1 test: 98%, for Genexus/OPA: 96%. Median TAT for OCA: 21 days, for 9-in-1 test: 3 days, for Genexus/OPA: 4 days. The frequencies of genetic alterations detected in the 1st-/2nd-phase were EGFR: 17/24%, KRAS: 15/16%, HER2 ex20ins: 4/3%, ALK fusions: 3/3%, RET fusions: 3/2%, ROS1 fusions: 3/2%, MET ex14skip: 2/2%, BRAF V600E: 1/1%, NRG1 fusions: 0/0.2% and NTRK3 fusions: 0.05/0.04%. Overall percent agreement of 9-in-1 test compared with OCA for EGFR/KRAS/HER2/BRAF/MET/ALK/ROS1/RET/NTRK3 alterations was 98%, and that of OPA compared with OCA was 95%. The rate of patients who received targeted therapies as 1st-line treatment was significantly elevated in the 2nd-phase compared with the 1st-phase (510/3841 [13%] vs. 567/6826 [8%], p < 0.001). Through the genomic screening, 1410 (37%) and 1269 (18%) candidate patients for clinical trials of KRAS, HER2, BRAF, MET, ALK, ROS1, RET or TRK-targeted drugs were identified in the 2nd-phase and in the 1st-phase, respectively. The rate of patients who were actually enrolled into the genotype-matched clinical trials were also significantly higher in the 2nd-phase than in the 1st-phase (222 [6%] vs. 186 [3%], p < 0.001). In 1st-line treatments for advanced NSCLC patients, the median progression-free survival was 8.5 months (95% CI, 7.7−9.4) in the 2nd-phase (n = 1839) versus 6.1 months (95% CI, 5.9−6.3) in the 1st-phase (n = 4262) (p < 0.001). Conclusions: Both the 9-in-1 test and Genexus/OPA had short TATs (3−4 days), high success rates (96−98%) and good concordance (95−98%) compared with another NGS assay (OCA). These rapid multi-gene assays highly contributed to enabling precision medicine and the development of targeted therapies for advanced NSCLC.

e21097 Background: Although anti-PD-1/PD-L1 monotherapy has achieved clinical success in non-small cell lung cancer (NSCLC), definitive predictive biomarkers remain to be elucidated. We assumed that by combining gene expression signatures with patient clinical data, we could identify a novel promising biomarker to predict response to anti-PD-1/PD-L1 monotherapy in NSCLC patients. Moreover, the characterization of these signatures will help us to decipher the complexity of tumor-immune interactions and better understand the tumor microenvironment (TME) that favors clinical response to nivolumab monotherapy. Methods: From clinically annotated NSCLC patients (n = 40) with nivolumab monotherapy in the second- or later-line settings, we prospectively collected tumor tissues and peripheral blood mononuclear cells (PBMCs) before first dose of nivolumab and PBMCs after first 4 or 5 doses of nivolumab. All tumor tissue and PBMC samples obtained were applied to whole-transcriptome sequencing (RNA-seq). We extracted transcriptomic datasets of lung adenocarcinoma (LUAD) (n = 20) and lung squamous cell carcinoma (LUSC) (n = 18) from the results, separately analyzed each histological subtype. To elucidate biological processes associated with clinical outcomes, we performed a supervised gene set enrichment analysis (GSEA) approach and an unsupervised single sample scoring approach. Results: In LUAD, we observed that gene sets related to interferon (type I and II) signaling (‘IFN signatures’) and antigen processing and presentation (‘APP signatures’) were significantly enriched in pre-treatment PBMCs of responders. IFN and APP signatures, which are closely related to each other, functionally cooperate to activate anti-tumor immune response. The enrichment of IFN and APP signatures provides the possibility that responders have a pre-existing anti-tumor immunity prior to nivolumab monotherapy. In LUSC, neither IFN nor APP signatures were enriched in pre-treatment tumor tissues and PBMCs of responders. Instead, gene sets related to the regulation of the TME (‘TME signatures’) are significantly enriched in pre-treatment tumor tissues of non-responders. The enrichment of TME signatures suggested that non-responders have an extremely immunosuppressive TME. These findings highlighted that responsive LUAD inherently have a high immunogenicity to elicit effective anti-tumor responses, whereas responsive LUSC have a similar level of immunogenicity as non-responsive LUSC but are free from an extremely immunosuppressive TME. Conclusions: We found that nivolumab enhanced anti-tumor immunity in patients with LUAD in a quite different way from patients with LUSC. Our study provides a blueprint for innovating combinational immunotherapy and supporting patient selection and treatment strategies on long-term clinical outcomes.

9081 Background: NEJ009 study is the first randomized phase III trial that compared gefitinib plus chemotherapy with gefitinib in patients with untreated NSCLC harboring EGFR mutations. We report an updated OS and long-term tolerability analysis, including subgroup analyses focusing on a type of EGFR mutation and metastatic sites. Methods: Patients were randomly assigned to gefitinib (gefitinib 250 mg PO, QD) and GCP regimen (gefitinib 250 mg PO, QD combined with carboplatin AUC 5 and pemetrexed 500 mg/m2 in a 3-week cycle for up to six cycles, followed by concurrent gefitinib and pemetrexed maintenance). This study tested multiple primary endpoints, PFS, PFS2, and OS, which were analyzed using a preplanned hierarchical sequential testing method. Results: Three hundred forty-five patients were randomly assigned (gefitinib, n = 172; GCP, n =170). At latest data cut-off (May 22, 2020), although there was no significant difference in OS between the groups (HR, 0.82; 95% CI, 0.64 to 1.06; P=0.13), GCP still demonstrated significantly better PFS and PFS2 compared to G. The updated median PFS, PFS2, and OS was 11.2 months, 18.0 months, and 38.5 months in the gefitinib group and 20.9 months, 20.9 months, and 49.0 months in the GCP group, respectively. No severe adverse events occurred in the period since the first report. Conclusions: This updated analysis confirmed that the GCP regimen achieved significantly better PFS and PFS2 with an acceptable safety profile compared with gefitinib alone. The efficacy outcome of GCP is more favorable than gefitinib monotherapy as first-line treatment of NSCLC with EGFR mutation. Clinical trial information: UMIN000006340. Clinical trial information: UMIN000006340. [Table: see text]

9590 Background: BRAF mutations are functionally classified into three groups, comprisingV600-mutant kinase-activating monomers (class I), kinase-activating dimers (class II), kinase-inactivating heterodimers (class III). The difference of clinical outcomes and concomitant genetic alterations among the three classes in non-small cell lung cancers (NSCLC) are unclear. Methods: We have prospectively analyzed NSCLC patients (pts) for cancer-related genes by a next-generation sequencing system, Oncomine™ Comprehensive Assay, in a large-scale genome screening project in Japan (LC-SCRUM-Japan). The clinical characteristics and outcomes of pts with BRAF-mutated non-squamous (non-sq) NSCLC were comparatively evaluated among the three classes of BRAF mutations. Results: A total of 5166 non-sq NSCLC pts were enrolled into the LC-SCRUM-Japan from 2015 to 2019. BRAF mutations were detected in 176 pts (3%). Among the 176 pts, 153 (87%) were classified into the three classes according to the mutation variants, including 65 (42%) into class I, 52 (34%) into class II and 36 (24%) into class III. The remaining 23 were not classified into any of the three classes. Compared with class I, class II or class III was significantly associated with smoking (P = 0.02 and < 0.01, respectively). Concomitant RAS mutations were significantly more frequent in class II and class III than in class I (P < 0.01 and = 0.04, respectively). The frequency of concomitant STK11 mutations was significantly higher in class III than in others (P < 0.01, respectively). There was no significant difference in the frequency of other oncogene and tumor suppressor gene mutations among the three classes. In the 1st-line platinum-containing chemotherapies for advanced or recurrent cases, median progression-free survival (mPFS) of class III pts was shorter than class I or class II pts (4.2, 11.5 and 4.8 months, I vs III; P < 0.01, II vs III; P = 0.06). In the treatment with 2nd-4th line PD-1/PD-L1 inhibitors, mPFS was not significantly different among the three classes. Overall survival of class III pts was significantly shorter than class I pts (11.9 vs 35.2 months, P = 0.03). Conclusions: Concomitant gene mutations and clinical features are largely different among the BRAF mutation classes. Especially in class III, concomitant RAS and STK11 mutations are more frequent and clinical outcomes were significantly less favorable. These results suggest the need of novel therapeutic strategy based on the mutation class for BRAF-mutated lung cancers.

9530 Background: The SWI/SNF chromatin remodeling complex is reported to be involved in sensitivity and resistance to immune checkpoint inhibitor (ICI). However, their role in non-small cell lung cancer (NSCLC) remains unclear. We examined the relationship between SWI/SNF complex mutations and clinical outcomes of ICI in patients with NSCLC. Methods: Of 1017 lung cancer patients enrolled in LC-SCRUM-IBIS, 350 patients were analyzable for whole-exome sequencing (WES). WES data were used to analyze the presence of mutations in 29 major subunits of the SWI/SNF complexes. ARID1A and SMARCA4 mutations were also evaluated in a targeted NGS panel (Oncomine comprehensive assay, OCA). PD-L1 expression by 22C3, tissue tumor mutational burden (tTMB) by WES, STK11 and KEAP1 mutations by WES or OCA were also assessed. Durable clinical benefit (DCB) including CR, PR and SD > 6 mos to ICI, progression-free survival (PFS) and overall survival (OS) were compared in status of each of SWI/SNF complex mutations and other factors. Results: At least one mutation in any subunits of the SWI/SNF complex was present in 28% of NSCLC patients. The most common mutated subcomplexes were SMARCA4 (12%), BAF (7%: ARID1A, 4%), non-canonical BAF (3%), PBAF (3%), and SMARCA2 (2%). Of 101 NSCLC patients treated with PD-1/PD-L1 inhibitors, SMARCA4 mutations tended to be associated with lower DCB (16 vs 31%) and shorter median PFS (1.9 vs 3.6 m) and OS (7.4 vs 18.1m). Patients with ARID1A mutations tended to have better clinical outcomes (DCB, 40 vs 28%) compared to those without mutations. No significant associations were found between PD-L1 expression and SMARCA4 or ARID1A mutations. Patients with STK11/KEAP1 mutations had lower rate of PD-L1 expression (TPS > 50%) (18% vs 48%, P = 0.03) and worse clinical outcomes (DCB, 6 vs 33%) compared to those without mutations. There was no significant association between a tTMB status and clinical outcome. Conclusions: SMARCA4 and ARID1A mutations appear to affect clinical outcomes of ICI in NSCLC patients. These findings indicate that SWI/SNF complex mutations may serve as a predictive biomarker for ICI in NSCLC patients.

8527 Background: It is unknown which regimen is the best in concurrent chemoradiotherapy (CCRT) of locally advanced non-squamous non-small cell lung cancer (NSCLC). Our previous randomized phase Ⅱ study, NJLCG0601, showed that chemoradiotherapy with uracil/tegafur (UFT) and cisplatin achieved promising efficacy with acceptable toxicities. In this trial, this regimen was compared to a regimen with pemetrexed and cisplatin for stage Ⅲ non-squamous NSCLC. Methods: Patients with inoperable stage Ⅲ non-squamous NSCLC were randomized to UFT 400 mg/m2 on days 1–14 and 29–42, and cisplatin 80 mg/m2 on days 8 and 36 (UP), or pemetrexed 500 mg/m2 and cisplatin 75 mg/m2 on days 1, 22, and 43 (PP). Involved-field radiotherapy (IFRT) was administered from day 1 to a total dose of 66 Gy radiotherapy in 33 fractions. Consolidation chemotherapy after CCRT was not planned for this study. The primary endpoint was 2-year overall survival (OS), with expected rates of 55% and a lower limit of 35% (alfa 0.05, beta 0.2). Secondary endpoints were the objective response rate (ORR), progression-free survival (PFS), OS, and toxicity profile. Results: From November 2010 to June 2017, 86 patients were enrolled from 11 institutions. Of the 85 eligible patients, the rate of 2-year OS was 78.6% (95% CI: 62.8–88.3%) in the UP arm and 85.5% (95% CI: 70.5–93.2%) in the PP arm. The ORR was 76.7% in the UP arm and 81.0% in the PP arm. With a median follow-up of 54 months, median PFS and OS were 12.3 and 64.2 months in the UP arm, and 26.2 months and not reached in the PP arm, respectively. Grade 3/4 febrile neutropenia was more frequent in the UP arm than in the PP arm (14.0%, 2.0%, respectively). Grade 3/4 pneumonitis occurred in 7.0% and 4.8% of patients in UP and PP arms, respectively. Conclusions: Both regimens with IFRT achieved the expected 2-year survival rate. PP had more favorable results than UP in terms of OS and PFS. We selected the PP arm for the next step.

9038 Background: Previous clinical trials demonstrated that alectinib (ALEC) had a longer time-to-progression than crizotinib (CRZ) in 1st-line settings. Information on long-term overall survival (OS), however, is still limited with a few studies having reported that the sequential strategy of “CRZ followed by other ALK-inhibitor” can provide extended OS. In Japan, ALEC was approved for a 1st-line setting earlier than in other countries. Methods: We reviewed the clinical data of ALK-rearranged NSCLC patients who received CRZ or ALEC between May 2012 and Dec 2016. Patients were divided into two groups according to the first-administered ALK inhibitor, the CRZ or ALEC group. In order to evaluate the efficacy of the sequential strategy of “CRZ followed by ALEC”, the combined time to treatment failure (TTF) was calculated in the CRZ group as defined by the sum of the “TTF of CRZ” plus the “TTF of ALEC” if patients were treated with ALEC followed by CRZ. In the ALEC group, the “TTF of ALEC” was calculated. The primary endpoint is the comparison between the combined TTF in the CRZ group with the TTF in the ALEC group. Results: Of 864 patients enrolled from 61 institutions, 840 patients were analyzed. Median age was 61 (range, 20-94); 56% were female; and 95% had adenocarcinoma. There were 535/305 patients in the CRZ/ALEC group. In the CRZ group, 282 patients received ALEC after CRZ failure. The combined TTF in the CRZ group was significantly longer than TTF in the ALEC group; median, 34.4 vs 27.2 months (mo); hazard ratio (HR), 0.709 [95%CI;0.559- 0.899]; P= 0.0044. However, there was no significant difference in OS between the patients who received ALEC after CRZ in the CRZ group and the patients in the ALEC group; median, 88.4 months vs. not reached; HR 1.048 [95%CI;0.758-1.451]; P= 0.7770. In the whole population, the CRZ group had a significantly shorter OS than the ALEC group; median, 53.6 mo vs not reached HR, 1.821 [95%CI;1.372-2.415]; P< 0.0001. Conclusions: The combined TTF in the CRZ group was significantly longer than TTF in the ALEC group, however, OS benefit of sequential therapy of CRZ followed by ALEC was not shown. Clinical trial information: UMIN000028605.

e20531 Background: Our previous phase 3 study established carboplatin plus the oral fluorinated pyrimidine formulation S-1 as a standard option for first-line treatment of advanced non–small cell lung cancer (NSCLC) (J Clin Oncol 2010; 28:5240). The importance of maintenance therapy for patients with advanced squamous NSCLC has been unknown, however. Methods: WJOG7512L was designed as a randomized phase 3 study to evaluate whether maintenance therapy with S-1 improves clinical outcome after induction therapy with carboplatin plus S-1 in such patients. Before randomization, patients received carboplatin (AUC of 5 on day 1 every 3 weeks) plus S-1 (40 mg/m2 twice per day on days 1 to 14 every 3 weeks) as induction therapy. Those who did not progress after four cycles of induction therapy were randomized to receive either S-1 plus best supportive care (BSC) or BSC alone. The primary objective was to confirm the superiority of S-1 plus BSC with regard to progression-free survival. Results: Of the 365 patients enrolled, 347 participated in the induction phase and 131 of these individuals were randomized to receive S-1 plus BSC ( n = 67) or BSC alone ( n = 64). Baseline demographics and clinical characteristics of the subjects, including the response to induction therapy, were well balanced. Patients receiving S-1 plus BSC showed a significantly reduced risk of disease progression compared with those receiving BSC alone (hazard ratio [HR], 0.548; 95% confidence interval [CI], 0.374–0.802; P = 0.0019). Median overall survival from randomization did not differ significantly between the two arms: 17.8 months for BSC alone and 16.7 months for S-1 plus BSC (HR, 0.890; 95% CI, 0.583–1.357). Time to deterioration in quality of life also showed no significant difference ( P = 0.8754 for FACT-TOI, P = 0.9016 for FACT-LCS). The incidence of adverse events during maintenance therapy was low, with neutropenia, anemia, and thrombocytopenia of grade 3 or 4 each occurring in ~1% to 4% of patients. Conclusions: Maintenance with S-1 plus BSC is an effective and well-tolerated treatment option for patients with advanced squamous NSCLC. Clinical trial information: UMIN000010396.

9005Background: Although EGFR-TKI alone has been a standard first-line treatment for pts with advanced NSCLC with EGFR mutations, our phase II study (NEJ005) showed promising efficacy of GCP. NEJ00...

9037 Background: EGFR-activating mutations (eg, exon 19 deletions [ex19del], L858R) occur in ~50% of East Asian patients with non-small cell lung cancer (NSCLC) and confer sensitivity to tyrosine kinase inhibitor (TKI) treatment. ASP8273, an orally administered EGFR TKI that inhibits EGFR-activating mutations, has demonstrated clinical activity in subjects with EGFR mutation-positive (EGFRmut+) NSCLC. Methods: EGFR TKI-naïve adult subjects (≥20 yr) with EGFRmut+ NSCLC were enrolled in this single arm Phase 2 study conducted in Japan (NCT02500927). Subjects received open-label ASP8273 300 mg once daily until discontinuation criteria were met. Primary endpoint was tolerability; secondary endpoint was antitumor activity defined by RECIST v1.1. Results: A total of 31 Japanese subjects (12 M/19 F; median age 64 years [range: 31–82]) were enrolled. Based on local testing, 27 subjects had an ex19del (n = 13, 42%) or a L858R (n = 14, 45%) EGFR activating mutation; 4 subjects (13%) had other EGFR activating mutations (L861Q [n = 2], G719X [n = 2]). ASP8273 300 mg had tolerable adverse events with diarrhea and peripheral neuropathy being most common; no interstitial lung disease events were reported (Table). Across all 31 subjects, based on investigator assessment, treatment with 300 mg ASP8273 was associated with an overall response rate (ORR) of 52%, disease control rate (DCR) of 94%, and a median duration of progression-free survival (PFS) of 11.3 months (95% CI: 7.2, 15.5). In subjects with ex19del, ASP8273 300 mg was associated with an ORR of 46% and DCR of 85%; median PFS was 8.3 months (95% CI: 2.9, -). In subjects with the L858R, ASP8273 300 mg was associated with an ORR of 57% and DCR of 100%; median PFS was 15.5 months (95% CI: 7.2, 15.5). Conclusions: Once-daily ASP8273 300 mg was tolerable in TKI-naïve Japanese subjects with EGFRmut+ NSCLC and demonstrated antitumor activity. Clinical trial information: NCT02500927. [Table: see text]

7520 Background: When this trial was planned, A was believed to be a promising new anthracycline agent for sensitive-relapsed SCLC. While re-challenge of P that had been used for the first-line tre...