4CPS-266 Afatinib as firstline treatment for advanced lung adenocarcinoma in a patient harbouring exon 19 deletion in EGFR: a case report

Background and importanceSomatic mutations in the tyrosine kinase domain of EGFR, including in-frame deletions in exon 19 (exon-19 del) and the L858R point mutation in exon 21, are common mutations accounting for 80–90% of EGFR mutations in non-small cell lung cancer (NSCLC). NSCLC with these types of mutations is particularly sensitive to afatinib treatment which covalently binds to and irreversibly blocks signalling from all homo- and heterodimers formed by the ErbB family members EGFR (ErbB1), HER2 (ErbB2), ErbB3 and ErbB4.Aim and objectivesWe present the case of a male patient, who never smoked, diagnosed with stage IV NSCLC harbouring an exon 19 deletion mutation who achieved a complete response to firstline afatinib treatment.Material and methodsThis was an observational retrospective study of the use of afatinib in a 46-year-old man diagnosed with NSCLC. Data were obtained from the electronic medical records.ResultsThe patient was diagnosed with non-squamous NSCLC stage IV in February 2019. He had a considerable lesion localised in the right lower lobe (RLL), 6.28×5.27 cm in transverse and craniocaudal diameter and metastatic lesions (cerebellum metastasis (2.4×2.1 cm), bilateral lung metastases). The patient had no comorbidities. He started treatment with afatinib 40 mg/day in February 2019. After 10 months, the RLL lesion diminished considerably, from 6.28×5.27 cm to 4.4×3.2 cm, and cerebellum metastasis from 2.4×2.1 cm to 1.6×1.8 cm, achieving a durable partial response. In February 2020, bilateral lung metastases had disappeared and he underwent a right lower lobectomy and lymphadenectomy and in March brain radiosurgery, reaching a complete response which was maintained. This patient continued treatment for 19 months. Side effects were grade 1 diarrhoea which allowed him to continue his treatment without delays.Conclusion and relevanceAfatinib represents an important firstline option for patients with advanced NSCLC harbouring an EGFR sensitising mutation, having been shown to prolong progression free survival compared with chemotherapy and the first generation EGFR TKI. Moreover, subanalyses of the prospective LUX-Lung 3, 6, and 7 and FLAURA trials indicated that afatinib and osimertinib were active in patients with CNS lesions. These agents should be considered as firstline treatments of choice in patients with EGFR mutation positive NSCLC and brain metastases.References and/or acknowledgementsConflict of interestNo conflict of interest