292. CHEMOTHERAPY AND CHEMORADIOTHERAPY FOR ADENOCARCINOMA OF THE OESOPHAGUS AND JUNCTION WITH OLIGOMETASTASES: RESULTS OF THE TNT-OES-1 TRIAL

Abstract Background Chemotherapy (FLOT) and chemoradiotherapy (CROSS) are both effective as neoadjuvant regimens for esophageal and junctional cancer. Total Neoadjuvant Therapy (TNT) aims to increase efficacy by combining chemotherapy with chemoradiotherapy. Although TNT is increasingly used in rectal cancer, there are no data on combining e.g. FLOT and CROSS in esophageal cancer. This phase-II study aimed to evaluate the feasibility and safety of the TNT FLOT-CROSS combination in esophageal and junctional adenocarcinoma patients with oligometastatic disease. Methods Patients with oligometastatic (defined as a maximum of four lesions in up to two organs, excluding lymph nodes) esophageal adenocarcinoma were treated with four biweekly cycles of FLOT followed by response evaluation (CT-scan). Patients without disease progression (RECIST v1.1) proceed to CROSS. Afterwards, response was assessed by CT-scan, endoscopy with biopsies and endoscopic ultrasonography with fine-needle aspiration on indication. The multidisciplinary tumor board discussed whether patients could proceed to four additional cycles of FLOT or local therapy of metastases and/or esophagectomy. Primary endpoint was tolerability of TNT FLOT-CROSS, defined as the proportion completing four cycles of FLOT and five cycles of chemoradiotherapy. Secondary endpoints included progression-free survival (PFS), disease control rate (DCR), toxicity and the proportion proceeding to local therapy of metastases and/or esophagectomy. Results Twenty patients (85% males, median age 62.5 years (interquartile range 58.3-66) were included of whom 16 (80%) had a single metastatic lesion. Eighteen patients (90%) successfully completed FLOT and fifteen (75%) completed TNT FLOT-CROSS (Figure 1). Toxicity mainly consisted of grade 1-2 leukopenia/neutropenia during FLOT, leading to treatment delay in twelve patients and dose-limiting of oxaliplatin in one patient. One patient had malaise grade 2. No grade 3-5 toxicities occurred during CROSS. Following TNT FLOT-CROSS, ten patients underwent four additional cycles of FLOT and toxicity resulted in treatment delay and dose reduction in seven patients and hospitalization in two patients. Six patients underwent esophagectomy of whom two underwent local treatment of metastases. The 1- and 2-year PFS was 56% and 48%. Three months after TNT FLOT-CROSS completion, DCR was 73%. Conclusion(s) This study showed that sequencing TNT FLOT-CROSS in patients with oligometastatic esophageal adenocarcinoma is feasible and comes with manageable toxicity and promising efficacy. In follow-up to this study, the TNT-OES-2 study will assess the efficacy and feasibility of TNT FLOT-CROSS and TNT CROSS-FLOT in patients with resectable nodal-positive adenocarcinoma of the esophagus or esophagogastric junction.