Preclinical study demonstrates senolytic mitigation of radiation-induced cutaneous fibrosis

A National Cancer Institute study showed that the senolytic ABT-263 mitigates radiation-induced cutaneous fibrosis in mice by disrupting a senescence-driven fibroblast-macrophage feed-forward loop.

Researchers analyzed cutaneous tissues of C3H/HeN mice irradiated with 35 Gy using spatial whole-transcriptomic profiling, identifying patterns of macrophage activation, extracellular matrix remodeling, and a SASP-rich microenvironment.

In vitro assays showed that irradiated fibroblast-derived SASP induced a senescent phenotype in unirradiated fibroblasts and macrophages.

The SASP-induced senescent-like macrophages acquired a CD206+ profibrotic phenotype and worked in tandem with activated fibroblasts to amplify IL-6 and collagen production.

This SASP exposure elevated Bcl-2 family protein expression in both fibroblasts and macrophages, increasing their susceptibility to the senolytic agent ABT-263.

In vivo administration of ABT-263 (50 mg/kg/day) starting 5 weeks post-irradiation depleted senescent fibroblasts and CD206+ macrophages, reduced IL-6, and mitigated dermal fibrosis assessed at 150 days.

The findings reveal a novel multicellular mechanism where senescent-like macrophages and activated fibroblasts form a reciprocal feed-forward loop that drives pathological fibrosis.

This study offers concrete preclinical proof-of-concept that targeting cellular senescence using Bcl-2 family inhibitors can prevent or reverse late radiation-induced skin injuries, an area with limited clinical options.

The research validates Bcl-2 family proteins as therapeutic targets to clear senescent populations responsible for complex tissue pathologies.

Evidence of therapeutic efficacy in localized skin injury may encourage developers of senolytics to expand their pipelines beyond broad systemic aging toward highly targeted, post-radiotherapy fibrotic indications.

Translational research assessing whether human clinical candidates targeting the Bcl-2 pathway show similar spatial and therapeutic profiles in radiation-induced fibrosis models.