What does this research mean for the field?

Small molecule inhibitors induce predominantly low-grade alopecia in cancer patients, with incidence rates varying significantly by drug class, ranging from 9% to 63% and peaking with Hedgehog pathway inhibitors. Novelty: ClaimNovelty.SYNTHESIS. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To characterize the incidence and severity of alopecia caused by small molecule inhibitors in cancer patients.

April 5, 2026

Abstract 5229: Hair loss in cancer patients receiving small molecule inhibitors: Evidence from clinical trials

Key Points

To characterize the incidence and severity of alopecia caused by small molecule inhibitors in cancer patients.
Conducted a scoping review of PubMed and Embase
Included clinical trials that reported alopecia in cancer patients treated with small molecule therapies
Excluded preclinical studies, case reports, case series, reviews, and biologic therapies
Synthetically extracted data on alopecia incidence and severity from 18 included trials
Alopecia incidence varied from 9% to 63% across different therapies
Hedgehog pathway inhibitors showed the highest incidence rates of 20-63%
FGFR and other kinase inhibitors had moderate alopecia rates between 22-48%
Aromatase inhibitors and the aurora B kinase inhibitor BI 811283 reported lower rates of 9-21%
Most alopecia cases were grade 1-2, with grade 3 or higher in less than 1%

Abstract

Abstract Alopecia remains one of the most common and distressing side effects of cancer therapy. While traditionally associated with cytotoxic chemotherapy, increasing evidence shows that small molecule inhibitors, targeting pathways such as FGFR, BRAF, and Src/ABL, can also induce clinically significant hair loss. However, incidence and severity patterns remain poorly characterized across small molecule inhibitor monotherapy. A scoping review of PubMed and Embase was conducted to identify clinical trials reporting alopecia in cancer patients treated with small molecule therapies. Eligible agents included kinase inhibitors (e.g., BRAF, KIT, FGFR, multikinase, Hedgehog pathway) and hormonal agents. Studies were excluded if they comprised preclinical studies, case reports, case series, reviews, or biologic therapies. Data on alopecia incidence, severity, and clinical presentation were extracted and synthesized qualitatively across small molecule drug classes. Eighteen clinical trials were included in this review, with alopecia incidence ranging from 9% to 63%. Hedgehog pathway inhibitors induced the highest overall rates, ranging from 20-30% with saridegib and glasdegib, and up to 63% with vismodegib. FGFR inhibitors (pemigatinib, infigratinib) and other kinase inhibitors (ripretinib, vemurafenib, sorafenib, AZD0424) demonstrated moderate rates (22-48%). Lower alopecia incidence was reported with aromatase inhibitors (anastrozole, lenostrozole) and the aurora B kinase inhibitor BI 811283, ranging from 9 to 21%. Across these monotherapies, alopecia was predominantly grade 1-2, with grade 3 alopecia or above occurring in less than 1% of patients. Although alopecia events were low-grade, their psychosocial impact remains significant. The higher incidences seen with Hedgehog inhibitors, compared with aromatase inhibitors, highlight how pathway-specific disruption of follicular signaling contributes to hair loss. Further research into the molecular mechanisms of these agents may help clinicians better anticipate and manage this side effect. Citation Format: Isabella Kamholtz, Simonetta I. Gaumond, Joaquin Jimenez. Hair loss in cancer patients receiving small molecule inhibitors: Evidence from clinical trials 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 5229.

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