A systematic review of head-to-head trials of approved monoclonal antibodies used in cancer: an overview of the clinical trials agenda

Background: Since 1997, several monoclonal antibodies (mAbs) targeting the same receptor or its ligand have been approved for use in oncology. However, no studies have summarized head-to-head trials of these mAbs. Methods: Systematic search of the biomedical literature and ClinicalTrials.gov for randomized studies comparing mAbs targeting the same receptor or its ligand that have been completed and published, completed and unpublished, or ongoing. We extracted trial characteristics including phase, indication, enrollment or target enrollment, randomization, primary endpoint and sponsor. Results: Twenty-two approved cancer mAbs had at least one other approved mAb targeting the same receptor or its ligand, totaling 41 different oncology indications. These include 5 anti-CD20 mAbs, 5 anti-PD1/PDL1 mAbs, 4 anti-HER2 mAbs, 3 anti-EGFR mAbs, 3 anti-VEGF mAbs and 2 anti-IL6/IL6R mAbs. Seventeen were completed and published and 14 were unpublished or ongoing trials. The completed and published trials enrolled 11,373 patients and tested 13 mAbs (13/22, 59%). Additionally, 13 (76%) contained drugs manufactured by the same company and 13 (76%) reached conclusions felt to be favorable to the sponsor. Of the 14 ongoing/completed unpublished trials, there is a total target enrollment of 3404 patients with 9 mAbs tested. Of these, 86% (12/14) are testing mAbs manufactured by the same company and 71% (10/14) are sponsored by the company that made the drug being tested. Conclusions: Most trials test drugs manufactured or sponsored by the same company. An overview of clinical trials agenda may lead to more uniform testing, helping clinicians make better evidence-informed prescribing decisions.