Confined copper depletion via a hydrogel platform for reversing dabrafenib/cetuximab resistance in BRAFV600E-mutant colorectal cancer

BRaf^V600E-mutant colorectal Cancer (CRC) is resistant to most first-line therapeutics, including the BRaf Inhibitor dabrafenib and epidermal growth factor receptor (EGFR) inhibitor cetuximab. Although copper depletion shows promise in reversing dabrafenib/cetuximab resistance in BRaf^V600E-mutant CRC, its application is limited by the potential for excessive copper depletion in non-tumor objects. In this study, we have developed a hydrogel platform for confined copper depletion in BRaf^V600E-mutant CRC cells, which effectively reverses dabrafenib/cetuximab resistance and enhancing therapeutic efficiency. The hydrogel platform enables precise intracellular copper depletion through localized administration, acidity-triggered drug release, and oxidized activation of a copper prochelator. The dosage of this prochelator is 37.5 μg/kg in mouse models, which is significantly lower than the commonly used tetrathiomolybdate. Furthermore, both dabrafenib and the prochelator are preloaded into acid-responsive nanoparticles before being embedded in the hydrogel matrix to facilitate efficient endocytosis and acid-activatable drug release. Confined copper depletion inhibits MEK1 signaling and suppresses the MAPK signaling pathway when combined with BRaf and EGFR inhibitors. Moreover, the hydrogel platform inhibits tumor growth and prolongs survival in subcutaneous and postsurgical models of BRaf^V600E-mutant CRC. This study provides an innovative strategy for overcoming dabrafenib/cetuximab resistance in BRaf^V600E-mutant CRC through precise intracellular copper depletion.

BRAF(V600E); Colorectal cancer; Copper depletion; Drug resistance; Hydrogel; Nanoparticles.