CUP during the treatment of MUP – Metastasis of a squamous cell carcinoma during targeted therapy of a metastatic melanoma

Introduction Only ten years ago there were few therapeutic options for patients with unresectable metastatic melanoma. Prognosis was poor with a 5-year survival rate of less than 10%. In 2013 the FDA and EMA approved Dabrafenib (a selective BRAF inhibitor) and in 2014 the combination therapy of Dabrafenib and Trametinib (a selective inhibitor of MEK1 and MEK2) as targeted therapy for advanced melanoma. Despite having changed the outcome considerably, there has also been seen adverse side effects such as cutaneous squamous cell carcinoma in 14-26% of patients.

Case report This is a 67-year-old male who was diagnosed with metastatic melanoma of unknown primary (MUP) in 2016. He underwent surgical resection of the metastasis and started combination targeted therapy with Dabrafenib and Trametinib in 2018. After five months a dose reduction of Dabrafenib and end of treatment with Trametinib was necessary due to severe side effects. During the following years, the patient stayed in full remission under monotherapy with Dabrafenib. In March 2022 MRI showed a mass in the left side pterygopalatine fossa. The result of a biopsy was a metastasis of squamous cell carcinoma and a panendoscopy showed no primary site. This is the first report of a squamous cell carcinoma of unknown primary under targeted therapy with Dabrafenib.

Discussion Targeted therapy of advanced and metastatic melanoma offers a considerably better prognosis to patients. Adverse side effects such as squamous cell carcinomas should be considered and the patient informed accordingly.

Conclusion  When screening patients under targeted therapy for skin adverse effects the physician should also think of initial manifestation in the lymph nodes. A regular screening including imaging is of significant importance.

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Artikel online veröffentlicht:
12. Mai 2023