Dermatological Toxicities of Targeted Therapy

Introduction

Targeted therapies are a rapidly expanding group of anticancer drugs, which promise to provide better tolerated and higher efficacy medications compared with conventional systemic chemotherapy. Inhibition of novel pathways or molecules brings about some unexpected and unforeseen adverse effects which are similar, yet distinct to those seen with chemotherapy. Cutaneous toxicity is the most common adverse drug reaction seen with targeted therapy. It ranges from benign, easily reversible effects to more life-threatening toxicity, which may even require cessation of therapy. Treatment of these adverse reactions poses different challenges, and thus, it is important to understand their clinical manifestations and mechanisms of action to aid in providing appropriate therapy.

Acneiform Rash

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  Incidence: Acneiform rash is the most common side effect of tyrosine kinase inhibitors (TKIs), reportedly seen in 50% to 100% of treated cases. This rash can affect not only the quality of life of patients but can also decrease compliance to therapy. For example, acneiform rash is very common with epidermal growth factor receptor (EGFR)–targeting agents. Both the incidence (81%–100%) and the frequency of grade 3 rash (15%) are highest with afatinib when compared with gefitinib or erlotinib. Cetuximab is reported to have a slightly lower incidence of 75% to 91%.