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Background: Large cell neuroendocrine carcinomas (LCNEC) are rare pulmonary malignancies. Reported survival rates are heterogeneous and the optimal therapeutic strategy is still debated. The prognosis of LCNEC is generally inferior compared to other non-small lung cancers. In early stages, surgery is recommended but might not be sufficient alone. Methods: We retrospectively analyzed all consecutive LCNEC patients operated at three institutions with curative intent between May 2005 and January 2017. Data retrieved from individual clinical databases were analyzed with the aim to identify prognostic parameters. Results: A total of 251 patients with LCNEC underwent curative intent surgery during the observation period. The median age was 64 years, 156 patients (62.2%) were male and 88.4% were smokers. The pathologic AJCC stage was I in 136 patients, II in 77, III in 33, and IV in 5 patients. Median followup was 26 months. Lymphatic vessel invasion (P=0.031) was identified as significant prognostic factor by multivariable analysis. There was a trend towards decreased survival in patients with blood vessel invasion (P=0.067). Even in earlier tumor stages, adjuvant chemotherapy had a positive effect on survival. The overall 1-, 3- and 5-year survival rates were 79.2%, 48.6% and 38.8% respectively. Conclusions: Lymphatic invasion (L1) is an independent prognostic factor. Surgery in LCNEC is beneficial in early tumor stages and platinum-based adjuvant chemotherapy may help in achieving better long-term outcomes resulting in most obvious survival differences in stage Ib. CA extern

Background MAP2K1 mutations are rare in non-small cell lung cancer (NSCLC) and considered to be mutually exclusive from known driver mutations. Activation of the MEK1-cascade is considered pivotal in resistance to targeted therapy approaches, and MAP2K1 K57 N mutation could be linked to resistance in preclinical models. We set out this study to detect MAP2K1 mutations and potentially targetable co-mutations using a molecular multiplex approach. Methods Between 2012 and 2018, we routinely analyzed 14.512 NSCLC patients with two next-generation sequencing (NGS) panels. In a subset of patients, fluorescence in-situ hybridization was performed to detect rearrangements or amplifications. We assessed clinical parameters and co-occurring mutations and compared treatment outcomes of different forms of systemic therapy. Results We identified 66 (0.5%) patients with MAP2K1 mutations. Both adenocarcinoma (n = 62) and squamous cell carcinoma (n = 4) histology. The presence of the mutations was linked to smoking, and transversions were more common than transitions. K57 N was the most frequent MAP2K1 mutation (n = 25). Additional mutations were found in 57 patients (86.4%). Mutations of TP53 were detected in 33 patients, followed by KEAP1 mutations in 28.1%. 24 patients (36.4%) had either MAP2K1-only or a co-occurring aberration considered targetable, including EGFR mutations, a BRAF V600E mutation and ROS1 rearrangements. Outcome analyses revealed a trend toward benefit from pemetrexed treatment. Conclusion Our analysis shows that MAP2K1-mutated NSCLC patients might frequently present with potentially targetable aberrations. Their role in providing resistance in these subtypes and the possible therapeutic opportunities justify further analyses of this rare NSCLC subgroup.

9050 Background: Recently reported, extended follow-up data from KEYNOTE-024 or -010 indicates that non-small-cell lung cancer (NSCLC) patients can experience long-term benefit from immunotherapy irrespective of discontinuation (per protocol: 35 cycles ∼24 months) or type of response in computed tomography (CT). Similar results were observed in the pooled analysis of 5-year follow-up data from CheckMate-017 and -057. This raises the question, whether patients may safely discontinue immunotherapy after achieving durable response. However, recently published results from CheckMate-153 demonstrated inferior survival rates in patients ceasing immunotherapy after one year, therefore optimal treatment duration of immunotherapy in advanced NSCLC remains unknown. Protocols from published Phase-III trials implemented treatment for a period of approximately 24 months or until evidence of disease progression or unbearable toxicity. Therefore, the ideal duration of immunotherapy remains unclear, and finding markers of beneficial outcome is of great importance. Here, we determine the proportion of complete metabolic responses (CMR) in patients that have not progressed after 24 months of immunotherapy. Methods: This is a retrospective analysis of forty-five patients with positron emission tomography using 2-[18F]fluoro-2-deoxy-D-glucose (FDG-PET) imaging for assessment of residual metabolic activity after at least 24 months of immunotherapy. Lesion-uptake in FDG PET on or below background level (using mediastinum as reference) was considered as CMR. Time until best objective morphological response including disease stabilization was measured from start of immunotherapy until first stable CT-scan (i.e. no progression or further response compared to previous scan) using RECIST 1.1. Results: Out of 45 patients, 29 patients had a CMR (64%). CMR was observed more frequently in non-first line patients. Patients with CMR were younger (median 65.7 vs. 75.5, P = 0.03). Fourteen patients with CMR have discontinued therapy and have not progressed until time of analysis; however median follow-up was only 5.6 (range 0.8-17.0) months. Conclusions: After a minimum of 24 months of palliative immunotherapy for NSCLC, CMR occurred in almost two thirds of patients. Potentially, achievement of CMR might identify patients, for whom palliative immunotherapy may be safely discontinued.

Introduction Although KRAS mutations in NSCLC have been considered mutually exclusive driver mutations for a long time, there is now growing evidence that KRAS-mutated NSCLC represents a genetically heterogeneous subgroup. We sought to determine genetic heterogeneity with respect to cancer-related co-mutations and their correlation with different KRAS mutation subtypes. Methods Diagnostic samples from 4507 patients with NSCLC were analyzed by next-generation sequencing by using a panel of 14 genes and, in a subset of patients, fluorescence in situ hybridization. Next-generation sequencing with an extended panel of 14 additional genes was performed in 101 patients. Molecular data were correlated with clinical data. Whole-exome sequencing was performed in two patients. Results We identified 1078 patients with KRAS mutations, of whom 53.5% had at least one additional mutation. Different KRAS mutation subtypes showed different patterns of co-occurring mutations. Besides mutations in tumor protein p53 gene (TP53) (39.4%), serine/threonine kinase 11 gene (STK11) (19.8%), kelch like ECH associated protein 1 gene (KEAP1) (12.9%), and ATM serine/threonine kinase gene (ATM) (11.9%), as well as MNNG HOS Transforming gene (MET) amplifications (15.4%) and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) amplifications (13.8%, exclusively in G12C), we found rare co-occurrence of targetable mutations in EGFR (1.2%) and BRAF (1.2%). Whole-exome sequencing of two patients with co-occurring phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA) mutation revealed clonality of mutated KRAS in one patient and subclonality in the second, suggesting different evolutionary backgrounds. Conclusion KRAS-mutated NSCLC represents a genetically heterogeneous subgroup with a high frequency of co-occurring mutations in cancer-associated pathways, partly associated with distinct KRAS mutation subtypes. This diversity might have implications for understanding the variability of treatment outcome in KRAS-mutated NSCLC and for future trial design.

Background The goals of this multinational retrospective study were to describe treatment patterns and survival outcomes by receipt of molecular testing and molecular status of patients with advanced non-small cell lung cancer (NSCLC). Methods This chart review study, conducted in Italy, Spain, Germany, Australia, Japan, Korea, Taiwan, and Brazil, included 1440 patients with newly diagnosed advanced (stage IIIB/IV) NSCLC initiating systemic therapy from January 2011 through June 2013, with follow-up until July 2016. We evaluated treatment patterns and survival by histology, line of therapy, molecular testing, and test results for epidermal growth factor receptor (EGFR) mutation and/or anaplastic lymphoma kinase (ALK) rearrangement. Country-specific data were analyzed descriptively and presented as ranges (lowest to highest country). Overall survival (OS) was estimated using Kaplan-Meier method. Results Patients with ≥1 molecular test varied from 43% (Brazil) to 85% (Taiwan). Numerically greater proportions of patients who were female, Asian, or never/former-smokers, and those with nonsquamous histology or stage-IV NSCLC, received a test. Testing was common for nonsquamous NSCLC (54%, Brazil, to 91%, Taiwan), with positive EGFR and ALK tests from 17% (Brazil and Spain) to 67% (Taiwan) and from 0% (Brazil) to 60% (Taiwan), respectively. First-line treatment regimens for nonsquamous NSCLC with positive EGFR/ALK tests included targeted therapy for 30% (Germany) to 89% (Japan); with negative/inconclusive test results, platinum-based combinations for 88% (Japan) to 98% (Brazil); and if not tested, platinum-based combinations for 80% (Australia) to 95% (Japan), except in Taiwan, where 44% received single agents. Median OS from first-line therapy initiation was 10.0 (Japan) to 26.7 (Taiwan) months for those tested and 7.6 (Australia/Brazil) to 19.3 (Taiwan) months for those not tested. Conclusions We observed substantial variation among countries in testing percentages, treatment patterns, and survival outcomes. Efforts to optimize molecular testing rates should be implemented in the context of each country’s health care scenario.

e20550 Background: Patient selection, dosing regimens and resistance mechanisms for immune checkpoint inhibitor combination therapy remain unmet medical needs in lung cancer. Combining blockade of PD-1 and CTLA-4 can be more effective than monotherapy but is accompanied by an increase in toxicity. Thus, to circumvent unnecessary toxicity it is of great interest to identify patients who will benefit from PD-1/PD-L1 blockade alone and to add ipilimumab only in case of primary or secondary progression. We present interim data from the non-small-cell lung cancer (NSCLC) cohort of the ongoing BIOLUMA trial which evaluates efficacy and safety of nivolumab and ipilimumab in lung cancer with a broad translational program to identify potential biomarkers predictive of response and/or resistance including whole exome sequencing (WES) of serial biopsies, functional analysis of peripheral T-cells and gut microbiome analyses. Methods: BIOLUMA is a multicentre non-randomised phase II trial in 2nd line patients with non-squamous NSCLC. Patients are treated with nivolumab 240 mg until disease progression and subsequently with a combination therapy of nivolumab 3 mg/kg q2w and ipilimumab 1mg/kg q6w. Primary endpoint is overall response rate (ORR) after addition of ipilimumab to nivolumab treatment. Analysis of sequential tumor biopsies, blood and gut microbiome is performed at different timepoints. Results: To date, 26 patients have been enrolled and 9 patients were transferred to the combination therapy after progression on nivolumab monotherapy. Drop out rate between the treatment arms is high, mainly due to rapid disease progression and adverse events which don’t allow addition of ipilimumab. ORR is available for 8 of these patients: 6 patients (75%) had PD as best response, and 1 (12.5%) each had a stable disease and partial response, respectively. The patient who achieved a PR had experienced primary tumor progression on nivolumab monotherapy before. Toxicity rate was similar to what has been reported from other trials. Conclusions: In NSCLC, addition of ipilimumab to nivolumab in nivolumab refractory patients seems to be safe, but the response rate is low and the drop out between the treatment parts high. Given these data, early termination of this cohort is currently discussed. Clinical trial information: NCT03083691.

Introduction: This study examines whether neoadjuvant chemoradiationtherapy combined with surgery improves survival rates when compared with other treatment strategies. Methods: We analysed 225 NSCLC patients with positive N2-nodes, who received various treatment between 2009 and 2014. Median follow-up and overall survival (OS) were defined from date of diagnosis to last known contact. Overall survival was estimated using Kaplan-Meier methods. Results: Mean age was 70 +/- 10 years. 13 patients received only radiationtherapy (RT), 36 patients neoadjuvant chemoradiotherapie and surgery (CRT-S), 38 patients were primary operated and received adjuvant chemoradiotherapie (S-CRT), 120 patients received chemotherapy (CTX) and 18 patients received best supportive care (BSC). Median follow-up was 15.1 month. Overall survival is represented in figure 1. Median overall survival in CRT-S group was 522.5 days (average 763 days), in CTX group was 283 days (average 424 days), in S-CRT group was 287.5 days (average 515.8 days), in RT group was 318 days (average 370.8 days), in BSC group was 12.5 days (average 50 days). Conclusion: This study demonstrates that therapy of choice for NSCLC patients with N2 positive nodes (both IIIA and IIIB clinical stage) is neoadjuvant chemoradiotherapy followed by radical surgery for improved overall survival.

Introduction Rearrangements of RET are rare oncogenic events in patients with non–small cell lung cancer (NSCLC). While the characterization of Asian patients suggests a predominance of nonsmokers of young age in this genetically defined lung cancer subgroup, little is known about the characteristics of non-Asian patients. We present the results of an analysis of a European cohort of patients with RET rearranged NSCLC. Methods Nine hundred ninety-seven patients with KRAS/EGFR/ALK wildtype lung adenocarcinomas were analyzed using fluorescence in situ hybridization for RET fusions. Tumor specimens were molecularly profiled and clinicopathological characteristics of the patients were collected. Results Rearrangements of RET were identified in 22 patients, with a prevalence of 2.2% in the KRAS/EGFR/ALK wildtype subgroup. Co-occurring genetic aberrations were detected in 10 patients, and the majority had mutations in TP53 . The median age at diagnosis was 62 years (range, 39–80 years; mean ± SD, 61 ± 11.7 years) with a higher proportion of men (59% versus 41%). There was only a slight predominance of nonsmokers (54.5%) compared to current or former smokers (45.5%). Conclusions Patients with RET rearranged adenocarcinomas represent a rare and heterogeneous NSCLC subgroup. In some contrast to published data, we see a high prevalence of current and former smokers in our white RET cohort. The significance of co-occurring aberrations, so far, is unclear.

e20664 Background: Fibroblast growth factor receptor 1 ( FGFR1) amplification in squamous cell non-small cell lung cancer (sqNSCLC) has been described as potential oncogenic and targetable driver in cell lines and murine models. However, a phase I study evaluating FGFR 1-3 inhibitor BGJ398 showed moderate response rate of 11% in FGFR1amplified sgNSCLC treated with dose ≥ 100mg. To identify underlying mechanisms of resistance, we analyzed tumor tissues of selected patients. Methods: Within the phase I BGJ398 study, patients (pts) with FGFR1amplified sqNSCLC were treated orally with escalating dose (5 to 150mg) of BGJ398 once daily (QD) or 50mg twice a day. In the expansion phase, pts received BGJ398 either continuously QD or on a 3-weeks on/1-week off schedule. CT scans for response were performed every 8 weeks. Available tumor tissue of pts treated with BGJ398 at our center was analyzed using hybrid capture–based massively parallel sequencing (CAGE). Results: Twenty-one pts with FGFR1 amplified sqNSCLC were treated with ≥ 100mg BGJ398 at our site. As best response, 3 pts showed partial response (PR), 7 pts stable disease (SD) and 7 pts progressive disease (PD). Two pts withdrew their consents and 2 pts died ahead of first CT scan: one due to infection and one due to sudden death. We performed CAGE covering 256 genes on 9 patients: on 3 pts with PR, 2 pts with SD, 2 pts with PD and 2 pts who died before first CT scan. All analyzed patients harbored mutations in TP53. Additionally, we detected two CDKN2A (one patient with PR and one patient who died before first CT) and three MLL2 stop codon and frame shift mutations (two patients with SD and one patient with PD). Of interest, we identified three patients with two canonical (one patient with SD and one patient who died before first CT) and one non-canonical mutations in PIK3CA(one patient with SD). Conclusions: In our analysis, MLL2 and PIK3CA mutations seem to have a negative impact on response in FGFR1 amplified pts treated with BGJ398. Further analysis with higher patient number is needed to identify the role of MLL2 and PIK3CA mutations in FGFR1 amplified sqNSCLC. Clinical trial information: NCT01004224.

e20059 Background: MAP2K1 mutations are rare in non-small cell lung cancer (NSCLC) and considered to be mutually exclusive with known driver mutations. Activation of the MEK1-cascade might play a pivotal role in resistance to targeted inhibition of BRAF V600E, EML4-ALK and EGFR T790M. So far, however, only MAP2K1 K57N could be identified and linked functionally to resistance in preclinical models. Clinical trials combining specific inhibitors for predefined NSCLC subgroups with MEK inhibitors are ongoing. We sought to characterize frequency and type of MAP2K1-mutated NSCLC regarding curated targetable aberrations. Methods: Tumor tissue collected consecutively from 4590 NSCLC patients within the German Network Genomic Medicine (NGM) between 07/2014 and 07/2015 was analyzed for MAP2K1 mutations using next-generation sequencing (NGS) with a set of 102 amplicons in 14 genes. Clinical and molecular characteristics of these patients were determined and compared with an internal control group of NSCLC patients and an independent control group of The Cancer Genome Atlas (TCGA). Results: We identified 21 (0.5%) patients with MAP2K1 mutations. They were frequently found in adenocarcinomas (n = 20) and were significantly associated with smoking. The most common MAP2K1 mutation was K57N. Most of the patients (n = 16) had additional oncogenic driver aberrations, including mutations in ALK, EGFR or BRAF, ROS1 rearrangements and MET amplification. TP53 mutations were found in 11 patients. In only five patients (23.8%) MAP2K1 occurred exclusively. TCGA analysis revealed additional 10 patients with MAP2K1 mutations, whereof 9 had additional TP53 mutations and one had BRAF mutation. Whereof most patients in our cohort had stage IV NSCLC, all patients in TCGA were systemic treatment naive. Compared with local stages in TCGA, our findings strongly suggest that targetable co-occurring mutations might occur more frequently in advanced stage NSCLC patients. Conclusions: MAP2K1 mutations co-occur frequently with targetable aberrations in smoking stage IV patients. Combination of targeted therapy against known driver aberrations with MEK inhibitors might be a promising therapeutic approach for such patients.