Introduction
The evolution of immune checkpoint inhibitors as an effective anticancer treatment constitutes one of the greatest and successful approaches in the world of anticancer therapy 1. They are widely used in the treatment of various cancers such as metastatic melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCCs), and urothelial cancer (UC)They are also employed in other types of malignancy such as head and neck squamous cell carcinomas (HNSCC), breast cancer, colorectal cancer, follicular lymphoma, ovarian cancer, pancreatic cancer, gastric cancer, sarcoma, colorectal cancer, metastatic merkel cell carcinoma (MCC), prostate cancer, and hematological malignancies1. Immune checkpoint inhibitors are of two types: drugs that target PD-1/PD-L1 proteins and drugs which target cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) protein. Drugs that act against PD-1 protein are known as PD-1 inhibitors; these are pembrolizumab, nivolumab, cemiplimab while drugs that act against PD-L1 protein are atezolizumab, avelumab, and durvalumab2. PD-1/PD-L1 inhibitors exhibit various immune-related adverse events, particularly due to the misguided stimulation of the immune system. Various organ-specific adverse effects related to anti-PD-1/PD-L1 therapy include gastrointestinal, endocrine, cardio, ocular, renal, and skin as well as adverse events attributed to systemic inflammation 3. Since their approval by the US Food and Drug and Administration (2014) and European Medicines Agency (2015), several cases of cutaneous adverse reactions were reported. The most frequent immune-related adverse events (irAEs) are related to cutaneous (dermatological) toxicities (Figure1). The characteristic of these irAEs ranges from non-specific eruptions to recognizable skin appearances, which may present acceptable to mild to life-threatening skin toxicities 4. Most of the cutaneous adverse reactions occurring with PD-1/PD-L1 inhibitors are usually mild to moderate in nature and readily manageable with proper supportive care, and usually resolved following their withdrawal from the drug regime. Thus, it is essential to establish a strong surveillance system to monitor the proper safety and toxicity profile of the potential PD-1/PD-L1 inhibitors. Early recognition is the key in the management and prevention of cutaneous irAEs, which may limit treatment interruption and can improve quality of life. The objective of this article is to evaluate the rate of cutaneous adverse reactions consistent with anti-PD-1 and anti-PD-L1 drugs and their associated control management.