Off-target engagement of sotorasib with PPARγ via FABP4: a novel mechanism driving interstitial lung disease

Sotorasib, the first FDA-approved KRAS G12C inhibitor, has demonstrated remarkable clinical efficacy in non-small cell lung cancer (NSCLC). However, its clinical utility is hampered by life-threatening interstitial lung disease (ILD), whose molecular basis remains unknown. Through the integration of transcriptomic and metabolomic analyses, we revealed that sotorasib activates PPAR-γ signaling, upregulating fatty acid oxidation (FAO) via its downstream effector CPT1B. This metabolic shift triggered mitochondrial ROS overproduction, which drives alveolar epithelial apoptosis and fibrosis in vivo and in vitro. Mechanistically, sotorasib directly binds to PPAR-γ via Thr325, facilitated by FABP4-mediated nuclear translocation, amplifying its transcriptional activity via a feedforward loop. Pharmacological inhibition of FABP4 attenuated PPAR-γ activation, mitigated ROS-driven apoptosis, and rescued pulmonary fibrosis in mice. Taken together, these findings identify the FABP4-PPARγ-CPT1b axis as a novel off-target mechanism of sotorasib-induced lung toxicity and propose FABP4 inhibition as a promising therapeutic target to enhance its clinical safety.