Exosomal cannabidiol: A promising candidate for targeted oral delivery against breast cancer.

Breast cancer (BCa) remains a leading cause of cancer-related deaths in women worldwide. Triple-negative BCa (TNBC) is highly metastatic with treatment limited by off-target toxicity. Cannabidiol (CBD) has anti-cancer and anti-inflammatory activity in BCa. This study addresses the poor oral bioavailability of CBD by utilizing exosomes (Exo) as a drug delivery system. CBD was loaded onto non-functionalized exosomes and folic acid-functionalized exosomes (FA-Exo), achieving an average CBD drug load of ∼20%. The FA-ExoCBD averaged 136 ± 2.9 nm in size. TNBC cell lines MDA-MB-231 and taxol-resistant MDA-MB-231TR were sensitive to growth inhibition by CBD than estrogen receptor positive (ER+) MCF-7 and its taxol-resistant derivative MCF-7TR. Exosomal formulations (ExoCBD and FA-ExoCBD) demonstrated time-dependent CBD release under physiologically relevant simulated gastric and intestinal conditions and withstand acidic conditions, retained canonical exosomal markers (CD81 and Alix) as well as physical parameters of exosomes including size, PDI and zeta potential. CBD downregulated key anti-apoptotic and anti-inflammatory markers. Oral FA-ExoCBD showed enhanced tumor targeting, tumor retention and inhibition of orthotopic MDA-MB-231-tumor growth in NOD Scid mice than ExoCBD or free CBD. RNA-Seq analysis of tumor tissues revealed that both CBD and FA-ExoCBD treatments modulated over 1000 genes, with FA-ExoCBD significantly downregulating IL13RA2 (associated with lung metastasis) and tumor biomarkers TRPM2 and SAMHD1, while upregulating tumor suppressors PRDM1, PCDHGB2, and ICAM1. These findings highlight the potential of FA-ExoCBD to enhance CBD's anticancer efficacy through targeted gene modulation. Overall, FA-ExoCBD improves CBD's therapeutic profile by enhancing efficacy, tumor selectivity, improved bioavailability and anticancer efficacy.