ESMO Congress 2023 | OncologyPRO

Abstract 1343P

Background

Amivantamab is a dual EGFR and MET inhibitor that has been approved for EGFR exon 20 mutations. Osimertinib-treated EGFRm patients may progress through cMET amplification. In such circumstances, amivantamab may be a salvage therapy. Here, we present 13 patients who received amivantamab on top of their previous EGFR TKI for disease progression (Group A - common EGFRm+ & Group B - EGFR Exon20+).

Methods

A retrospective case series study at Shaare Zedek Medical Center between October 2021 and March 2023 of patients who received amivantamab on top of previous EGFR TKI on progression outside of clinical trial after local IRB approval. The study aim to present safety as well as preliminary efficacy. Patient records served as the basis for data collection, PET-CT or CT scans were used to assess systemic response, and for followup. ORR was defined by RECIST 1.1.

Results

13 pts, 4 male 9 female, median age 65 years (range 45-73). 9 had common mutation (Group A) and 4 uncommon (Group B). 8 group A pts had osimertinib as last line, one afatinib while in Group B 3 pts had mobocertinib, and 1 had poziotinib. Amivantamab was administered on top of previous line in all pts (Table). The objective response rate (ORR) was 37.5% in group A and 25% in group B. Median duration of therapy (mDOT) was 2.3 months in group A and 5.5 months in group B (long – rank p value 0.38), The median progression-free survival was 4.7 months in both groups. Safety profile was driven mainly by amivantamab where grade ≥3 toxicity was nausea, diarrhoea, and skin rash (mainly scalp). 16% patients had a grade 3 infusion reaction.

Conclusions

Incorporating amivantamab to prior EGFR TKI treatment appears to be a feasible option, although osimertinib stands out as the most well-tolerated TKI with clinical efficacy. Further studies should aim to identify patient subgroups and confirm these findings through prospective analysis.