Circulating tumor DNA to guide furmonertinib monotherapy or combination therapy in advanced EGFR mutant non-small cell lung cancer (NSCLC): A randomized, open-label, multicenter study (FOCUS-C).

TPS9150 Background: Detection of EGFR ctDNA after several weeks EGFR-TKIs treatment was an effective method to identify prognosis of advanced EGFR mutant NSCLC patients. Patients with uncleared EGFR ctDNA had shorter progression-free survival (PFS) ( Mack PC et al; CCR 2022). However, whether they can benefit from EGFR-TKI combination therapy has not been reported. Furmonertinib (AST2818), a potent, orally bioavailable, highly brain penetrant, third generation EGFR-TKI with unique chemical structure designed to improve potency and specificity, showed superior efficacy compared with gefitinib as first-line therapy in EGFR mutant NSCLC along with an acceptable safety profile without new signals ( Shi, YK et al.; Lancet Respir Med 2022). We hypothesized that monitoring clearance of EGFR ctDNA in blood could rationally guide subsequent monotherapy or combination therapy with furmonertinib and will improve outcomes in patients with uncleared EGFR ctDNA. Methods: The FOCUS-C study is a multicenter, open-label, randomized study. Patients who are aged 18 years or older and have histologically confirmed, locally advanced or metastatic, stage IIIB, IIIC, or IV unresectable NSCLC with EGFR exon 19 deletions (19Del) or exon 21 Leu858Arg mutation (L858R) on tissue biopsy and plasma will be treated with furmonertinib. Eligible patients with uncleared EGFR 19Del or L858R ctDNA after 3 weeks furmonertinib treatment will be stratified according to EGFR mutation (19Del or L858R), central nervous system metastases (with or without) and detectable accompanying gene aberrances in plasma (with or without) and randomly assigned (2: 2: 1) to receive furmonertinib or furmonertinib plus chemotherapy (pemetrexed and carboplatin for 4 cycles followed by maintenance pemetrexed) or furmonertinib plus chemotherapy plus bevacizumab (pemetrexed, carboplatin and bevacizumab for 4 cycles followed by maintenance pemetrexed and bevacizumab) in 21-day cycles until disease progression, the occurrence of intolerable toxicities, withdrawal of consent, or other discontinuation reasons judged by the investigators. The primary endpoint is PFS between furmoneritnib plus chemotherapy versus furmonertinib alone. Secondary endpoints include PFS, objective response rate, duration of response, disease control rate, overall survival and safety. Several exploratory endpoints will also be evaluated based on ctDNA detection by next-generation sequencing (Genecast, Wuxi, China). The study is enrolling. 34 patients had been enrolled till 2nd Feb 2023. Clinical trial information: NCT05334277 .