Real-world effectiveness and safety of amivantamab for exon 20 EGFR-mutant non-small cell lung cancer (NSCLC) in French early access program: Amexon 20 GFPC.

e20529 Background: Amivantamab is a bispecific EGFR/MET antibody approved for patients with NSCLC with EGFR exon 20 insertions. In France, early access has made it possible to use it as a second or further-line treatment after at least one line of chemotherapy. Methods: This is a retrospective multicentric cohort of consecutive patients with an adenocarcinoma and EGFR exon 20 insertions, who received at least one dose of amivantamab as part of the French early access program from September 3th, 2021 (date of approval in the French early access program) until April 30 th , 2022. Patients gave consent for the data collection and were enrolled in 28 sites. Primary end point was Real world Progression free Survival (Rw PFS) and secondary endpoints were description of clinical characteristics, best response, duration of treatment, overall survival (OS), CNS activity, toxicities and subsequent treatment. Results: Thirty-nine patients received amivantamab in early French access. Median age was 60 years 39-83; 64 % of patients were female and 54% never smoker; 33% had PS 2 or more and 66 % had brain metastasis at inclusion. Amivantamab was administered as a second or third line and more in 30% and 70% of patients respectively. Patients received a median number of 10 injections 1-47. Overall, 37 patients were evaluable for response; response rate was 35 % and disease control rate (DCR) was 62%. After a median follow-up of 11.3 months 8-16.7, median Rw PFS and OS were 3.5 months 2.6-5.8 and 11.3 months 8-17.8 respectively. Rw PFS and OS at 6 months were 33.3% and 74.4% respectively. Duration of response was 5.8 months 2.3-11.9. Overall, 23 patients were evaluable for CNS response; 26 % had CNS response and CNS DCR was 69%. Main sites of progression were lung (43%), bone (28%), liver (12.8%) and brain (10%). Grade III/IV adverse events were reported in 11 patients (28.2%), mainly skin toxicity (n = 5), infusion reaction (n = 2), digestive disorders (n = 1), interstitial pneumonia (n = 1), neurological disorders (n = 1), fever (n = 1). Amivantamab was permanently discontinued due to toxicities in 4 patients (10.3%). Subsequent treatment was administered to 21 patients (53.8%) after amivantamab, mostly consisting of mono chemotherapy (n = 13). Conclusions: Our real-world multicenter analysis showed that amivantamab was an effective monotherapy treatment in second line and after for patients with EGFR exon 20 insertions. No new toxicities were reported.