Severe treatment-induced inflammatory polyarthritis in advanced melanoma patients: 2 case reports

Immune checkpoint inhibitors (ICI) and targeted therapies form the therapeutic mainstay for v-Raf murine sarcoma viral oncogene homolog B V600-mutated metastatic melanoma. Both treatment regimens can cause inflammatory arthritis. The reported incidence of treatment-induced inflammatory arthritis is low, though presumably underestimated due to lack of awareness, clear definitions and uniform grading systems. Nevertheless, recognition is important as inflammatory arthritis can become chronic and thus affect the quality of life beyond treatment. In this short communication, we present two patients with metastatic melanoma treated with ICI and targeted therapies who develop severe polyarthritis. Based on their clinical discourse we describe standard inflammatory arthritis treatment modalities and more advanced immunomodulatory treatment options with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or biologic DMARDs (bDMARDs). Long-term immunosuppressive treatment with glucocorticoids or DMARDs in this setting raises concerns about antitumour response and potential carcinogenic risk. Current literature on this topic is scarce, heterogeneous and retrospective. Prospective analysis of cancer patients treated with DMARDs is needed to clearly address these concerns.