Chemoradiation phase II trials: re-exploring a world of missed opportunities

Background: Phase II trials are designed to assess the efficacy/toxicity ratio of experimental treatments and select those worth being tested in phase III trials. Although crucial limitations were identified when concurrent chemoradiation (cCRT) phase III trials characteristics were assessed, features of cCRT phase II trials have never been reported. The objective was to describe features of all cCRT phase II trials. Methods and material: Requests were performed in the Medline database (via PubMed). The latest update was performed in April 2016, using the following MESH terms: 'clinical trials: phase II as topic', 'chemoradiotherapy'. Results: Four hundred and fifty-eight cCRT phase II trials were identified. They were mainly multicenter (51.5%), single arm studies (77.7%) published after 2011 (55.0%). The median number of included patients was 52. Primary endpoints were mainly response rate (20.5%), pathological complete response (14.4%) and overall survival (12.6%). The primary endpoint was not defined in 22% of studies. Tumors were mostly lung (23.1%), head and neck (20.3%), colorectal (16.6%) and esophagogastric cancer (14.6%) treated at a locally advanced setting (81.7%). 55.2% of trials used 3D-conformal radiotherapy and 9.1% intensity-modulated radiotherapy, mainly with normo-fractionation (82.0% of the 573 arms with radiotherapy). Radiation technique was not reported in 19.9% of studies. Associated anticancer drugs (563 arms) were mainly conventional chemotherapies (559 arms): cisplatin (46.2%) and 5-fluorouracil (28.3%). Non cytotoxic agents (targeted therapies, immunotherapies) were tested in 97 arms (17%). With a median follow-up of 31 months, acute grades 3-5 were reported in 98.5% of studies and late toxicities in 44.5%. Follow-up was not reported in 17% of studies. Conclusions: cCRT phase II trials featured severe limitations, with outdated radiation techniques, insufficient reporting of crucial data and a small number of included patients. This certainly limited the impact of conclusions and hindered the development of successful phase III trials.