Introduction: HER2 mutations occur in 1-3% of lung adenocarcinomas. With increasing use of next-generation sequencing at diagnosis, more patients with HER2-mutant tumors are presenting for treatment. Few data are available to describe the clinical course and outcomes of these patients when treated with afatinib, a pan-HER inhibitor. Methods:We identified patients with metastatic or recurrent HER2-mutant lung adenocarcinomas treated with afatinib among 7 institutions across Europe, Australia, and North America between 2009 and 2017. We determined the partial response rate to afatinib, types of HER2 mutations, duration of response, time on treatment, and survival.

9071 Background: Human epidermal growth factor 2 ( HER2, ERBB2) mutations have been identified as oncogenic drivers in 3% of lung cancers. Afatinib is an irreversible tyrosine kinase inhibitor of HER1 (EGFR), HER2 and HER4 and has been described in case reports to have activity in HER2-mutant lung cancers. However, there is little data to inform the clinical use of afatinib. Methods: We reviewed patients with metastatic HER2-mutant lung cancers treated with afatinib among 7 institutions between 2009 and 2016. The primary endpoint was investigator assessed overall response rate using RECIST v1.1. Other data collected included types of HER2mutations, duration of afatinib treatment and overall survival. Results: We identified 27 patients with metastatic HER2-mutant lung cancers treated with afatinib. Median age at diagnosis was 63 (range 40 to 84); majority were men (n = 16; 59%) and never-smokers (n = 18; 67%). All tumors were adenocarcinomas, and the majority were Stage IV at initial diagnosis (n = 16; 59%). A 12-base pair (bp) in-frame insertion YVMA in exon 20 (p.A775_G776insYVMA) was present in 16 patients (59%). In addition, there were three 9-bp insertions, two 3-bp insertions and two single bp substitutions (L755F and D769H) in exon 20; two single bp substitutions (S310F) in exon 8; one exon 17 V659E mutation; and one single-nucleotide polymorphism (Ile655Val). Median duration on afatinib was 2 months (range 1 to 27); median line of prior treatment was 3 (range 1 to 6). Eight patients had previously received trastuzumab prior to afatinib and one concurrently with afatinib. Overall response rate was 15% (n = 4; 95% CI 4 to 34%); the four partial responses lasted 5, 5, 6 and 10 months. The 3 longest partial responders had a 12-bp insertion in exon 20 (YVMA); the remaining partial responder had a 9-bp insertion in exon 20. Median overall survival from diagnosis date of metastatic disease was 23 months (95% CI 18 to 62). Conclusions: Afatinib produced partial responses in 15% of patients with metastatic HER2-mutant lung cancers, including insertion YVMA. Our findings confirm the activity of afatinib and provide data supporting a framework for its use in the care of patients with HER2-mutant lung cancers.

BackgroundPD1/L1 Immune Checkpoint Inhibitors (ICI) have significantly improved long-term outcome in about 20% of advanced Non Small Cells Lung Cancer (NSCLC) patients (pts), but 80% present primary or secondary resistance. The PIONeeR project (NCT03493581) aims to predict the response/resistance to PD1/L1 ICIs in advanced NSCLC pts through a comprehensive agnostic multiparametric and longitudinal biomarkers assessment. Data presented here are a focus on the quantification of tumor infiltration by lymphocytes, their activation as potential markers of the resistance to treatment by ICI.MethodsAdvanced NSCLC pts with available archived tumor tissue at screening visit (VS), treated with standard PD1/L1 ICIs (nivolumab, pembrolizumab or atezolizumab), alone (2nd line or more) or combined with chemotherapy (1st line), were re-biopsied at 6 weeks (V2) of treatment. PD1/L1 ICIs overall response rate (ORR) was assessed by RECIST 1.1 every 6 weeks. The multiplex IHC test ”Immunoscore® CR T Cells Exhaustion” (IS TCE) quantifies cytotoxic lymphocytes expressing three checkpoints: PD1, LAG3, TIM3, extrapolating their exhaustion status, both in the stroma and parenchyma. The unsupervised neural-network-based machine learning algorithm SOM (Self-Organizing Maps) was used to classify samples based on the 27 IS TCE variables. Statistical significance of survival differences between groups was evaluated using the log-rank test.ResultsAmong the first 100 pts, (male (64%), smokers (91,8%), <70yrs (69%), with an ECOG PS0/1 (97%), treated in 2nd line setting (86%)), 79 VS + 30 V2 biopsies were tested with IS TCE. SOM clustering highlighted four distinct clusters: a group with moderate T-cells infiltration (group 1), hot tumors with high T cells infiltration in both stroma and parenchyma (group 2), cold tumors with very low T cells infiltration (group 3), and finally, a highly distinguishable group with important T-cells density in stroma only (group 4). None of the 11 responders was present in the Group 3, ”Cold” cluster. The four groups presented different Progression Free Survival (PFS) rates (p=5,2e-4) with better relapse-free survival Groups 1 and 2. Additionally, V2/VS ratios showed lymphocytes recruitment induced by the treatment in parenchyma only: no significant lymphocytes recruitment was observed in the stromal compartment. Interestingly, the most recruited lymphocyte populations expressed PD1.ConclusionsIS TCE test may help stratifying and predicting responders to anti PD1/L1 therapy through checkpoint expressing lymphocytes quantification and spatial distribution. Additional tests performed on the PIONeeR cohort to explore other aspects of the immune response to cancer should complete these results.AcknowledgementsThis work is supported by French National Research Agency (ANR-17-RHUS-0007), a partnership of AMU, APHM, AstraZeneca, Centre Léon Bérard, CNRS, HalioDx, ImCheck Therapeutics, Innate Pharma, Inserm, Institut Paoli Calmettes and sponsored by AP HM. Drug supply is funded by AstraZeneca. Special thanks to patients and families.Trial RegistrationNCT03493581Ethics ApprovalThe study is conducted in accordance with Good Clinical Practice and the French applicable regulatory requirements (Public Health Code, article L.1121-1/La loi n° 2012–300 du 5 mars 2012 relative aux recherches impliquant la personne humaine (dite loi Jardé), the applicable subject privacy requirements, and the ethical principles that are outlined in the Declaration of Helsinski. The study was approved by the French Ethic Committee, CPP Ouest II - Angers, ref. CPP: 2028/08, Ref ANSM (French competent authority) 2018020500208, 2018072600120, 2019083000148. Freely given written informed consent was signed and obtained from each individual participating in the study, before any study specific procedure was undertaken and after the provision of information about the study by the investigator during a physician-patient consultation and sufficient time for reflection.