Fig 1: PUREG4‐OEI48 and PUREG4‐OCEI24 reduce tumor volume in an in vivo BC murine model. HCC1806 cells were inoculated in the mammary fat pad to induce tumors in a xenograft murine model (thymic nude Mus musculus). Treatment was administered every 3 days, beginning 17 days postinoculation and continuing until day 29, and (A) a tumor growth curve was constructed by measuring the weight and length and calculating the tumor volume. Upon euthanasia, (B) tumors were collected, and (C) the volume calculated. (D) The levels of toxicity markers were assessed by ELISA in the peripheral blood serum of mice: aspartate aminotransferase and α‐fetoprotein (hepatic toxicity), troponin I (cardiac toxicity), Park7 (neuronal toxicity), and creatinine (liver toxicity). (E) Representative sections of paraffin‐embedded, and hematoxylin and eosin (H&E) stained heart, liver, and kidney were evaluated. Comprehensive areas and magnified details of functional structures are presented for each organ. Images were captured in an imager Aperio AT2 Leica, using the software Aperio Scanner Console version 102.0.7.5. All experiments were performed in biological triplicates, and data are shown as mean ± SD. Statistical significance was determined using one‐way ANOVA followed by Sidak's multiple comparison test. Scale bars: heart and kidney, 2 mm; cardiac muscle, renal cortex, and renal medulla, 60 μm; liver, 500 μm; central vein, 80 μm.