Genomic aberrations involving erb-b2 receptor tyrosine kinase 2 ( ERBB2) are driver oncogenes in ∼2% of lung adenocarcinomas. However, the use of daily dosing of ERBB2 tyrosine kinase inhibitors (TKIs) - including afatinib - has been fraught by plasma concentrations that barely achieve preclinical model inhibition, significant patient-reported toxicities and limited clinical activity. We hypothesized that alternative dosing strategies could improve tolerability and efficacy.
We profiled lung cancer cell lines against TKIs and retrospectively evaluated the toxicity/response to pulse afatinib (280mg once weekly) in lung cancers with ERBB2 mutations.
An ERBB2 exon 20 insertion mutated lung cancer cell line had 50% inhibitory concentration to afatinib higher than the reported plasma concentration of afatinib 40mg daily. Three patients with advanced ERBB2 mutated lung adenocarcinomas were treated with off-label pulse afatinib. The 280mg weekly dose was well tolerated with no reported rash and minimal diarrhea. One TKI-naïve patient achieved a partial response for 5 months and another stable disease for 11 months.