Prevention and interception of triple-negative breast cancer and its metastasis to the brain with brain-permeant L024

Introduction: Estrogen receptor-negative (ER-neg) breast cancer (BC) disproportionatelyaffects younger women, women of African descent, and underserved populations. Nopreventive agents are approved for this subtype. ER-neg BCs, including triple-negative (TNBC)and HER2+ tumors, often metastasize to the brain early, yet remain undetected until neurologicsymptoms emerge, when prognosis is poor. Current therapies, including ER-neg adjuvantagents, offer limited brain efficacy due to poor blood-brain barrier penetration. Radio-surgicalinterventions for brain metastases have severe side effects with no survival benefit. There is acritical need for safe, risk-reducing therapies that prevent both ER-neg BC and braindissemination.We identified L024, a first-in-class agent with efficacy against ER-neg BC. Mechanistically, L024inhibits SREBP1-driven lipogenesis, suppresses the PI3K-AKT axis, and downregulates NF-κB-mediated inflammation, key pathways in ER-neg progression. We have demonstrated that L024suppresses tumor growth and we hypothesize that it will intercept early brain metastasis, offering a novel preventive and interceptive approach. Methods: We assessed L024's antiproliferative activity in six ER-neg BC lines: MDA-MB-231,HCC-1937, HCC-3153, 4T1, 4T1-BM2, and MDA-MB-231-Br using IncuCyte live cell imaging. Xenografts were developed using MDA-MB-231 cells in nude mice; L024 (80 mg/kg/day) was administered when tumors reached threshold size. Tumor growth was monitored over 28 days;RNA-seq was performed on excised tumors. Transwell assays with/without matrix assessedinvasion/migration of brain-tropic cells after a sublethal L024 dose (2.5-5 µM). Western blotswere performed after 24 h L024 (5 µM) exposure to assess downstream effectors. ADMEproperties were evaluated in silico (ACD Lab). PK was analyzed in female CD-1 mice dosed with L024 (50 mg/kg), with drug levels in plasma, mammary, and brain measured with LC-MS/MS, and modeled using SAAM II. Results: L024 significantly inhibited TNBC proliferation in a dose-dependent manner, with sustained effects six days post-treatment. It reduced tumor growth and epithelial-to-mesenchymal transition in the xenografts. Sublethal doses impaired invasion and migration ofbrain-tropic cells. Western blots showed reduced PI3K, AKT, and pAKT (Ser473). In silicoprofiling predicted CNS permeability: molecular weight <400 Da, LogP = 3.9, TPSA = 66.76 Ų,and no P-gp/BCRP efflux. In vivo PK confirmed high brain exposure (Kp >1 between 1-8 h),cleared by 24 h, supporting prevention/therapy potential. Conclusions: L024 reprograms metabolic pathways essential for ER-neg BC progression,specifically targeting multiple steps of the metastatic cascade. CNS PK supports furtherevaluation in immunocompetent TNBC models with brain metastatic potential.