ERX-41 is an orally active, stereospecific small molecule that targets lysosomal acid lipase A (LIPA). It induces endoplasmic reticulum (ER) stress, leading to cell death independently of its LIPA activity yet reliant on its ER localization, suggesting a role in targeted solid tumor therapies [1].

ERX-41 (1 μM; 0-30 h) induces cell death in MDA-MB-231 cells without significantly affecting normal human mammary epithelial cells (HMECs) [1]. Additionally, ERX-41 (1 μM; 2 h, 4 h) causes rapid endoplasmic reticulum expansion and peripheral endoplasmic reticulum disarray within 4 hours and 2 hours, respectively [1]. Moreover, ERX-41 (1 μM; 0.5-4 h) activates the unfolded protein response (UPR) pathway by promoting p-PERK and p-eIF2-α [1].

ERX-41 (10 mg/kg; oral or intraperitoneal injection; single dose) is detectable within the tumor 1.5 hours post-administration, regardless of the administration route [1]. A single oral dose of ERX-41 at 10 mg/kg significantly inhibits tumor progression in both the MDA-MB-231 and D2A1 xenograft mouse models without affecting mouse body weight [1].