Pathological Complete Response in an Advance Stage IIIB Non-small Cell Lung Cancer Secondary to Neoadjuvant Osimertinib Targeted Therapy: A Case Report and Review of Literature

Neoadjuvant chemotherapy is a therapeutic option for potentially resectable non-small cell lung cancer (NSCLC). The role of neoadjuvant targeted therapy (NTT) remains less explored. This case highlights the use of neoadjuvant osimertinib in a case of advanced NSCLC. A 67-year-old woman had a left lower lobe lung mass measuring 5.0 × 5.1 × 7.0 cm with an enlarged subcarinal lymph node (LN) on her positron emission tomography scan. Following biopsy, a diagnosis of stage IIIB N2 (cT3N2M0) EGFR exon 19 deletion mutation-positive lung adenocarcinoma was established. NTT using osimertinib 80 mg once daily was commenced. Subsequent re-imaging at 3 months (ycT2bN2M0), 6 months (ycT1cN2M0) and 9 months showed tumour downstaging and resolution of the subcarinal LN (ycT1cN0M0). She underwent left lower lobectomy with systematic nodal dissection. All surgical specimens demonstrated no evidence of malignant cells (ypT0N0). Osimertinib could be the preferred NTT for potentially resectable NSCLC.