Severe photosensitivity resulting from an interaction between encorafenib and nirmatrelvir/ritonavir in a patient with advanced melanoma: A Case Report

Nirmatrelvir/ritonavir (PAXLOVID^TM, Pfizer) is considered the first line treatment for mild to moderate COVID-19 infection. Ritonavir, a potent inhibitor of the cytochrome P450 3A4 (CYP3A4) isoenzyme, is susceptible to considerable drug-drug interactions with drugs that are metabolized by the CYP3A4 enzyme. Here, we report a case of severe photosensitivity in a patient taking encorafenib for metastatic melanoma after initiating nirmatrelvir/ritonavir treatment for COVID-19 infection. This case serves as a reminder that caution is required by physicians when prescribing nirmatrelvir/ritonavir to patients taking encorafenib or other molecular-targeted BRAF inhibitors for the treatment of V600 BRAF-mutant cancer.