Long term outcomes of phase I/II study of palliative triple metronomic chemotherapy in platinum-refractory/early failure oral cancer

Background Triple metronomic chemotherapy is one of the options of treatment in platinum-refractory/early failure oral cancer. However, long term outcomes with this regimen are unknown. Methods Adult patients with platinum-refractory/early-failure oral cancer were enrolled in the study. Patients were administered triple metronomic chemotherapy ie erlotinib 150 mg once daily celecoxib 200 mg twice daily and methotrexate weekly (phase 1 in variable dose 15-6 mg/m2 & 9 mg/m2 in phase 2), all taken orally till progression of disease or development of intolerable adverse events. The primary objective was to estimate the long-term overall survival and factors impacting it. The Kaplan Meier method was used for time-to-event analysis. Cox proportional hazard model was used to identify factors impacting overall survival (OS) and progression-free survival (PFS). The factors included in the model were age, sex, Eastern Cooperative Oncology Group -performance status (ECOG PS), tobacco exposure and a subsite of primary and circulating endothelial cell levels at baseline. A p-value of 0.05 was considered significant. Clinical trials information: CTRI/2016/04/006834. Results A total of 91 patients were recruited (15 in phase 1 & 76 in phase 2), the median follow-up was 41 months and 84 events of death had occurred. The median OS was 6.7 months (95% CI 5.4-7.4). The 1-year, 2-years and 3-year OS' were 14.1% (95% CI 7.8-22.2), 5.9% (95% CI 2.2-12.2) and 5.9% (95% CI 2.2-12.2) respectively. The only factor favorably impacting OS was the detection of circulating endothelial cells at baseline (HR = 0.46; 95% CI 0.28-0.75, P = 0.0020). The median PFS was 4.3 months (95% CI 4.1-5.1) and the 1-year PFS was 13.0% (95% CI 6.8-21.2). The factors with statistically significant impact on PFS were detection of circulating endothelial cells at baseline (HR = 0.48; 95% CI 0.30-0.78, P = 0.0020) and no tobacco exposure at baseline (HR = 0.51; 95% CI 0.27-0.94, P = 0.030). Interpretation The long-term outcomes with triple oral metronomic chemotherapy ie erlotinib, methotrexate and celecoxib are unsatisfactory. Detection of circulating endothelial cells at baseline is a biomarker predicting efficacy of this therapy. Funding The study was funded by an intramural grant from Tata Memorial Center Research Administration Council (TRAC) and Terry Fox foundation. Copyright (c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).