Panitumumab-associated stomatitis in metastatic colorectal cancer patients: clinical characterization and pathogenic considerations

Purpose: The aim of this study was to report the clinical characterization and management of oral lesions affecting metastatic colorectal cancer (mCRC) patients undergoing panitumumab-containing regimens. Methods: : Electronic medical records of mCRC patients referred to treat mouth sores during the treatment with the EGFR monoclonal antibody – panitumumab – were retrospectively reviewed at two centers. Patients’ characterization, clinical profile of oral lesions and management outcomes were documented. Additionally, modifications or discontinuation of the antineoplastic treatment as well as the occurrence of other adverse events (AEs) were analyzed. Results: : A total of 8 patients were included. The oral lesions appeared in a mean time of 9 days (range 7-11 days) following the first cycles. Mean reported pain scores was 6 (range 1-9), causing feeding discomfort. The oral lesions showed a marked aphthous-like appearance in all cases and involved non-keratinized mucosa more likely. Painful atrophic tongue lesions (25%) and angular fissures (37.5%) were also observed. Two patients (25%) required dose reductions or interruptions of the antineoplastic treatment and 1 patient (12,5%) needed discontinuation due to panitumumab-associated stomatitis. Dermatologic AEs were the most prevalent. Clinical improvement was obtained in all patients following management with topical corticosteroid therapy and/or photobiomodulation. Conclusion: Panitumumab-containing regimes were associated with a particular pattern of oral lesions consistent with stomatitis. Although the lesions responded satisfactorily to corticosteroids and photobiomodulation, modifications or discontinuation of the antineoplastic treatment may eventually occur. Anti-EGFR effects of panitumumab on oral mucosa cells homeostasis seem to play a central role in the pathogenesis of this event.