Somatostatin receptors: an alternative treatment target for advanced Merkel cell carcinoma.

Abstract

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer with a high risk of returning and spreading. It affects about 2500 new patients every year in the USA. Current effective treatments for advanced MCC include immunotherapy and chemotherapy. Immunotherapy helps a patient's immune system fight against cancer, but only half of MCC patients have long-term benefit. Chemotherapy works initially, but the cancer starts growing again after an average of 90 days. Moreover, chemotherapy can cause severe side-effects. Therefore, we need newer treatments for advanced MCC. Somatostatin analogues (SSAs), a therapy targeted to cancer cells that have somatostatin receptors (SSTRs) on their surface, works well in some cancers. In our study, we tested whether MCC cells have SSTRs on their surface, which would allow SSAs to bind, and whether SSAs fight well against MCC tumours. We first needed to know how often MCC tumours have SSTRs within the tumour cells because SSAs need to bind to SSTRs to work. We checked this by using somatostatin receptor scintigraphy (a special type of radiologic scan) in 40 patients and by pathologic staining (colouring the tumour cells on a biopsy with a dye for better visibility). Thirty-three of 39 (85%) patients had some level of SSTRs in their tumours. We then treated 19 of these patients with SSA, and about 40% of patients benefitted without bad side-effects. Our data supports that targeting SSTRs should be tested further in advanced MCC. Linked Article:Akaike et al. Br J Dermatol 2021; 184:319-327.