P3.13-19 Surgery for cIIIB Lung Adenocarcinoma After Response to Erlotinib, Survival and Management of Postoperative Oligoprogressions

Abstract

Down-staging of epidermal growth factor receptor (EGFR) activating mutation-positive (EGFR M+) advanced non-small-cell lung cancer (NSCLC) after first-line EGFR tyrosine kinase inhibitor (TKI) therapy may lead to primary tumor resection. Unfortunately, most patients’ disease will progress postoperatively even with the use of adjuvant TKI therapy mainly due to EGFR T790M mutation. Osimertinib, a third-generation inhibitor of EGFR T790M mutation, is with reduced toxicity profile as compared to non-selective EGFR TKI. Our aim is to assess a survival benefit of salvage lung resection in Stage IIIB lung adenocarcinoma after response to TKI and a management of oligoprogressions in the postoperative period. A Caucasian age 56 female lung adenocarcinoma patient (ECOG PS-0) was initially staged as cT2aN3M0 on October 10, 2015. Pretreatment biopsy specimens from ipsilateral scalene lymph node harbored EGFR mutation (exon 19 E746-T751insI deletions). After six months of first-line treatment with erlotinib150 mg/daily, which patient tolerated very well, a FDG-PET scan showed a 21/16 mm formation of the left upper lobe with SUV-2 without other abnormalities, down-staging with cT1cN0M0. Radical left upper lobectomy with 20 negative dissected mediastinal lymph nodes was carried out (May 17, 2016). Postoperative pathomorphological and mutational studies of residual tumor revealed adenocarcinoma and EGFR exon 19 mutation. Adjuvant erlotinib therapy was started for 3 months. Four months after its discontinuation by patient decision a 3 cm left supraclavicular mass (SUV-2.0 on FDG-PET) was diagnosed and totally resected. Adenocarcinoma involvements of 3 lymph nodes, as well as EGFR exon 19 mutation, were confirmed. The patient continued on erlotinib, but after 6 months on FDG-PET scan 2 left cervical lymph nodes (SUV 4.6 and 6.1 on FDG-PET) were diagnosed. Systematic left cervical dissection was performed with resection of four metastatic lymph nodes. Again adenocarcinoma histology was confirmed, but EGFR T790M mutation was identified as well. Three months later, even without signs of residual tumor mass on computerized tomography scan, Osimertinib therapy in dose 80 mg orally once daily was administered. The last follow-up FDG-PET scan revealed no signs of progression (April 30, 2018). The patient is with ECOG PS-0 and perfect quality of life without drug-related adverse events. Radical surgery of oligoprogression following salvage surgery for Stage IIIB (EGFR M+) lung adenocarcinoma after response to TKI, while continuing to use TKIs (specifically osimertinib in EGFR T790M mutation), can result in prolonged overall survival. The pending question is whether the EGFR-TKI therapy can be discontinued in these patients.