Current Research in Melanoma and Aggressive Nonmelanoma Skin Cancer

There have been several significant advances in cancer treatment in the last decade that are applicable to the treatment of melanoma and advanced nonmelanoma skin cancers. Among these are the development of immune checkpoint inhibitors targeting the programmed death protein-1 (PD-1)/programmed death legand-1 (PDL-1) axis, as well as targeted inhibitors of the BRAF/MEK signaling cascade in melanoma, and the hedgehog signaling pathway in basal cell carcinoma (BCC). These immune-based and targeted therapies have dramatically changed the treatment options for locally advanced and metastatic melanoma, Merkel's cell carcinoma, cutaneous squamous cell carcinoma (cSCC), and BCC. In this article, we will briefly review the currently approved targeted and immunotherapy-based treatments for locally advanced and metastatic melanoma, Merkel's cell carcinoma, and cSCC and discuss various combinations of approved therapies, as well as emerging therapeutic candidates that are currently in clinical trials, including novel checkpoint inhibitors in development, intratumoral oncolytic agents (viral and nonviral), and various immune-based therapies such as toll-like receptor (TLR) agonists, adoptive T-cell therapy, T-cell costimulation, and innate immune cell therapy. For advanced BCC, we will discuss trials investigating the currently approved smoothened (SMO) inhibitors for neoadjuvant use, emerging SMO inhibitors in development, topical SMO inhibitors, alternative targets in the hedgehog signaling pathway, and the use of anti-PD-1 agents for advanced BCC both alone and in combination with SMO inhibitors.