Two Cases of Generalized Ribociclib-Induced Vitiligo

CDK4/6 inhibitors, such as ribociclib, have revolutionized ER+/PR+/HER2- breast cancer treatment over the past decade. They are generally well-tolerated, with the most commonly reported cutaneous adverse events being rash and alopecia. However, we present two unique cases of diffuse vitiligo-like lesions developing after the ribociclib initiation. Our first patient developed vitiligo-like lesions approximately 7 months post-treatment, prompting discontinuation of the drug and initiation of oral steroids, tacrolimus ointment, and NBUVB phototherapy. This resulted in the stabilization of her vitiligo-like lesions. Our second patient developed cutaneous symptoms around 1.5 years following the initiation of ribociclib. She decided to continue ribociclib, declining topicals or phototherapy. Biopsies obtained from both patients demonstrated a lack of epidermal melanocytes. Although these lesions demonstrated signs of stabilization following treatment in our first case, no definitive treatments for CDK4/6 inhibitor-induced vitiligo exist to restore pigmentation. These findings also suggest that ribociclib-induced vitiligo has a highly variable temporal onset following drug initiation. Further investigation is required to minimize the long-term side effects of CDK4/6 inhibitor-induced vitiligo, establish therapy options, and encourage the continuation of cancer-directed therapy.