Afatinib (AFA) plus bevacizumab (BEV) combination after osimertinib (OSI) resistance in advanced EGFR-mutant NSCLC: A phase II study (ABCD-study).
Authors: Hata Akito , Katakami Nobuyuki , Takase Naoto , Kibata Kayoko , Yamanaka Yuta , Tamiya Motohiro , Mori Masahide , Kijima Takashi , Morita Satoshi , Sakai Kazuko , Nishio Kazuto 
Published: June 2022

9117

Background: After OSI failure, various resistant mechanisms such as C797S and uncommon EGFR mutations, or MET amplification have been reported. AFA is an irreversible EGFR-TKI with a potency as pan-HER inhibitor, including high sensitivity to uncommon EGFR mutations. Many clinical studies have also shown a synergy of EGFR-TKIs and VEGF inhibitors. Methods: ECOG PS 0-1 patients (pt) with EGFR-mutant NSCLC were enrolled after OSI resistance. AFA was prescribed at 30-40 mg QD, and BEV was administered at 15 mg/kg tri-weekly until progression. Plasma/histologic rebiopsied samples taken after OSI failure but before enrollment were analyzed to examine resistant mechanisms including gene alterations/copy-number gain using cancer personalized profiling by deep sequencing. Results: Between January 2018 and October 2020, 28 pts were enrolled. Mutation subtypes were: 9 (32%) Del-19; 5 (18%) Del-19+T790M; 5 (18%) L858R; 7 (25%) L858R+T790M; 1 (4%) Del-19+L858R+T790M; and 1 (4%) G719S. Median line of prior OSI was 2 (range, 1-9). CR/PR was obtained by prior OSI in 24 (86%) pts. Regarding AFA+BEV efficacy, one (4%) CR, 4 (14%) PR, and 17 (61%) SD were confirmed, resulting in response rate of 17.9% and disease control rate of 78.6%. Median DoR was 9.0 (range, 4.2-22.3) months. Median PFS and OS were 2.7 (95% CI, 2.0-4.6) months and not reached, respectively. Twenty-eight (100%) plasma and/or 21 (75%) histologic rebiopsies identified: 17 (61%) TP53; 15 (54%) T790M; 9 (32%) uncommon EGFR; 9 (32%) MET; 6 (21%) C797S; 3 (11%) BRAF; 2 (7%) HER2; 2 (7%) KRAS; and 2 (7%) PI3K mutations; or 14 (50%) EGFR; 6 (21%) MET; and 2 (7%) HER2 amplifications. One (4%) small cell transformation was found. Among 6 C797S pts, 1 CR, 4 SD, and 1 PD were confirmed. Three (33%) of 9 uncommon EGFR and 1 (50%) of 2 HER2 mutation positive pts achieved radiographic response. All 15 T790M-positive pts showed no response, but 5 (38%) of 13 T790M-negative pts responded to AFA+BEV. None (0%) of six pts with EGFR downstream signaling mutations such as BRAF, KRAS, or PI3K responded. Five (50%) of 10 pts without T790M/BRAF/KRAS/PIK3 mutations exhibited confirmed response. FAT1 mutation was found in two (40%) of 5 responded pts. Dose reduction/interruption of AFA was performed in 15 (54%) pts. Median number of BEV administrations was 4 (range, 1-32). There were neither TRD nor ILD. Adverse events ≥grade 3: hypertension (29%); proteinuria (7%); diarrhea (7%); and rash (4%) were observed. One (4%) grade 4 duodenal perforation was reported. Conclusions: AFA+BEV after OSI resistance demonstrated moderate efficacy and favorable safety. A small portion of C797S pts exhibited the sensitivity. Higher potency was suggested in T790M/BRAF/KRAS/PIK3 mutation-negative and uncommon EGFR/HER2 mutation-positive pts. Selected population could obtain clinical benefit from AFA+BEV, based on rebiopsy results after OSI resistance. Clinical trial information: UMIN000030545.