Abstract 5230: Alopecia in cancer immunotherapy: Incidence and patterns with monoclonal antibodies and antibody-drug conjugates

Abstract The treatment landscape in oncology is evolving, with a shift toward more targeted approaches, including biologic immunomodulators. These agents are designed to minimize systemic toxicity and offer greater precision than traditional chemotherapy, yet they are not without adverse effects. Emerging data suggests that biologic therapies, such as antibody-drug conjugates, immune checkpoint inhibitors, and interferons, may induce alopecia in cancer patients. A scoping review was conducted using PubMed and Embase to identify clinical studies reporting alopecia in cancer patients treated with biologic therapies. Eligible agents included monoclonal antibodies such as antibody-drug conjugates (e.g., trastuzumab deruxtecan), immune checkpoint inhibitors (e.g., anti-PD-1, anti-PD-L1, anti-CTLA-4) and cytokine-targeting biologics (e.g., interferons, anti-IL therapies). Case reports, preclinical studies, and reviews were excluded. Data on alopecia incidence, severity, and clinical presentation were qualitatively synthesized across antibody classes. Nine clinical trials met inclusion criteria, encompassing 1,924 patients. Antibody-drug conjugates (ADCs), including datopotamab deruxtecan, trastuzumab deruxtecan, tisotumab vedotin, enfortumab vedotin, and disitamab vedotin, showed the highest rates of alopecia, ranging from 37% to 56% (predominantly grade 1-2). These ADCs, which delivered topoisomerase I or microtubule inhibitors, were used in patients with breast, cervical, urothelial, non-small cell lung cancer, and other solid tumors. In contrast, immune checkpoint inhibitors such as cemiplimab (anti-PD-1) and trastuzumab (anti-HER2) were rarely associated with alopecia (1-2.2% incidence, grade 1-2) in lung and breast cancer patients, respectively. Interferon alfa-2b, a type I interferon receptor agonist, demonstrated a time-dependent effect, with alopecia (grade 1-3) reported in 9% of melanoma patients receiving one month therapy versus 28% in those on one year regimens. The higher incidence of alopecia observed with ADCs likely reflects the effects of the chemotherapeutic payloads they deliver, rather than the antibody itself. In contrast, antibody-only and interferon therapies demonstrated substantially lower rates (1-28%). Recognizing these trends across biologic classes can help clinicians set patient expectations, guide counseling, and implement supportive measures for those experiencing hair loss throughout treatment. Citation Format: Isabella Kamholtz, Simonetta I. Gaumond, Joaquin Jimenez. Alopecia in cancer immunotherapy: Incidence and patterns with monoclonal antibodies and antibody-drug conjugates [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5230.