Oral metronomic chemotherapy after definitive chemoradiation in esophageal squamous cell carcinoma: a randomized clinical trial

Background: Improving outcomes in locally advanced esophageal/GEJ squamous cell cancer (SCC) is an unmet need. We investigated the addition of oral metronomic chemotherapy (OMC) following definitive chemoradiotherapy (CRT). Materials and methods: This was a randomized open-label integrated phase II/III study in patients with SCC of esophagus/GEJ following definitive CRT who had no radiologic evidence of progression, and no endoscopically detected disease. Randomization was 1:1 to OMC (celecoxib 200 mg twice daily and methotrexate 15 mg/m weekly) for 12 months or observation. The primary endpoint for the phase II portion was progression-free survival (PFS); secondary endpoints were overall survival (OS) and toxicity. P ≤ 0.2 for PFS was required to proceed to phase III. Results: Between Jan 2016 and Dec 2019, we enrolled 151 patients for the phase II portion, 75 to OMC and 76 to observation. The tumor originated in the upper thoracic esophagus in 79% patients. Concurrent CRT consisted of median 63 Gy in a median of 35 fractions; concurrent chemotherapy was weekly paclitaxel + carboplatin in 91%. OMC was started at a median of 2.6 months (IQR 2.3–2.8) from CRT completion. Grade 3 or higher toxicities occurred in 18 patients (24%) in the OMC arm and 9 (12%) in the observation arm; P = 0.071. Median PFS was 25 months (95% CI, 17–58) in the OMC arm and was not attained [NA] (95% CI, 25–NA) in the observation arm; HR, 1.51, 95% CI, 1–2; P = 0.073. Median OS was 36 months (95% CI, 23–NA) in the OMC arm, and not attained (95% CI, NA–NA) in the observation arm; HR, 1.77; 95% CI, 1–2.9; P = 0.023. Conclusion: Oral metronomic methotrexate and celecoxib in patients who have not progressed radiologically and have no endoscopic evidence of disease following radical CRT for locally advanced esophageal/GEJ SCC does not improve outcomes and may lower survival. [Funded by the TMC-Research Administration Council (TRAC); CHROME study (CHemoRadiotherapy followed by Oral Metronomic therapy in Esophageal cancer); ctri.nic.in number: CTRI/2015/09/006204]. Trial registration number: CTRI/2015/09/006204.