WITHDRAWN: Neuropathic Cancer Pain in Patients Treated With an EGFR-Inhibitor

Abstract CONTEXT: Novel treatments of neuropathic pain (NP) are urgently needed. Based on repeated observation of rapid relief of neuropathic cancer pain (NCP) after single doses of intravenous epidermal growth factor receptor inhibitor (EGFR-I), we have successfully treated patients with and without cancer who suffer from severe, treatment-refractory NP with EGFR-Is. Pain research is complicated by endpoint subjectivity. Patients with advanced cancer are heterogeneous, with complex, fluctuating clinical pictures, hampering feasibility of standard drug-trial procedures. OBJECTIVES: To further explore the EGFR-I/NP association and to inform planning of controlled drug trials in patients with NCP. METHODS: Explorative, prospective, systematic observational study of patients with cancer and neuropathy receiving EGFR-Is. A variety of evaluation tools assessed patients' symptoms and tested feasibility for use in this population in light of regulatory requirements. Choice of assessment tool and frequency were based on what was ethical, feasible and clinically relevant for each patient in clinical practice. RESULTS: 20 patients with NCP were included between 01.2017 and 12.2020. All patients received the monoclonal antibody panitumumab. Fourteen of these 20 patients (70%) were considered clear clinical responders, based on patient and physician-reported outcomes. Implementing repeated patient reported outcomes presented challenges with regard to both content and timing. CONCLUSION: The results of this study support panitumumab's potential to be of significant benefit to patients with treatment refractory NCP. Findings also reinforce the difficulty of using conventional drug trial endpoints and designs in this patient group. Flexibility and innovative research methods must therefore be considered for much needed pivotal trials.