Alopecia due to chemotherapeutics, hedgehog inhibitors, targeted antibody therapies and immune checkpoint inhibitors : Pathogenesis, clinical picture, diagnostics and prophylaxis

The incidence and severity of alopecia vary mainly depending on the chemotherapeutic agent used or other drug groups. The pathogenetic characteristics of the different forms of alopecia are reflected in the clinical presentation and, in some cases, in the resulting recommendations for prophylaxis. To provide an overview of the pathogenesis, clinical presentation, diagnosis and prophylaxis of alopecia with chemotherapeutic agents, hedgehog inhibitors, targeted therapies and immune checkpoint inhibitors. Based on the current S3 guideline "Supportive therapy", an extensive literature search was carried out. Chemotherapy-induced hair loss (CIA) occurs in up to 65% of cases. Anagen effluvium is observed as early as 1-3 weeks after the start of treatment and is reversible in most cases. Alopecia associated with inhibitors of the Sonic Hedgehog signaling pathway (HHIA) such as vismodegib or sonidegib are observed in up to 60% of cases. They are characterized by telogen effluvium. BRAF or immune checkpoint inhibitors lead significantly less frequently to alopecia (BRAFA, CPIA). According to taxane-based chemotherapy protocols, scalp cooling can help to prevent higher-grade CIA. If CIA or other forms of alopecia are expected, early contact with self-help organizations and early prescriptions for wigs should be offered.