Cetuximab (EGFR IgG1) After PD-1 Failure Delivers 33% PR Rate in R/M HNSCC

Cetuximab is an EGFR-targeting IgG1 monoclonal antibody with potential immune-effector activity, evaluated as monotherapy in a non-randomized, single-institution cohort of recurrent/metastatic HNSCC progressing on or intolerant to PD-1 therapy ± chemotherapy (n=27; NCT04375384). Best overall response was 33.3% PR (9/27) and 37.0% SD (10/27), with median PFS 4.4 months and median OS 11.6 months; historical cetuximab monotherapy in platinum-refractory R/M HNSCC typically produced ORR around 10–13%, median PFS/TTP around 2–3 months, and OS around 5–6 months. Safety was notable for 2 first-infusion anaphylaxis events and universal acneiform rash, including 68% grade 3 rash requiring oral antibiotics, which appears higher than older cetuximab monotherapy experience.