Ibrutinib-loaded lipid nanocarriers exhibit antitumor effect in a human ex vivo skin model of melanoma.

Cutaneous melanoma is an aggressive skin cancer with high metastatic potential and frequent resistance to apoptosis-inducing therapies. Ibrutinib (IBR), a Bruton's tyrosine kinase inhibitor, has demonstrated antitumor potential, yet its topical application is not well established. This study evaluated the cytotoxic, antiproliferative, and skin permeation effects of free IBR and IBR-loaded nanostructured lipid carriers (IBR + NLC) using human melanoma cells (SK-MEL-28) and ex vivo human skin models. NLC + IBR presented enhanced toxicity towards melanoma cells by promoting necroptosis, as evidenced by the absence of caspase-3/7 activation, increased expression of RIPK1 and RIPK3, elevated LDH release, and plasma membrane disruption. In addition, mitochondrial depolarization was observed, likely as a consequence of necroptotic signaling and associated cellular stress. NLC + IBR significantly enhanced reactive oxygen species production, induced cell cycle arrest in the sub-G1 phase, and reduced CDK1 and CDK2 gene expression. Clonogenic and migration assays confirmed complete suppression of tumor cell colony formation and reduced migratory capacity following NLC + IBR treatment. Skin permeation studies revealed that NLC + IBR enabled deeper drug skin penetration, with reduced retention in the stratum corneum and higher accumulation in the viable skin layers, the primary therapeutic target in cutaneous melanoma. Finally, using an ex vivo human skin model of melanoma, NLC + IBR promoted melanoma cell necrosis, while maintaining a favorable topical safety profile with no significant irritation. These findings suggest that NLC + IBR topical application is a promising strategy for localized treatment of cutaneous melanoma, particularly in early-stage or adjuvant contexts.