Synergistic administration of photothermal therapy and chemotherapy to cancer cells using polypeptide-based degradable plasmonic matrices

Aim: Resistance of cancer cells to hyperthermic temperatures and spatial limitations of nanoparticle-induced hyperthermia necessitates the identification of effective combination treatments that can enhance the efficacy of this treatment. Here we show that novel polypeptide-based degradable plasmonic matrices can be employed for simultaneous administration of hyperthermia and chemotherapeutic drugs as an effective combination treatment that can overcome cancer cell resistance to hyperthermia. Method: Novel gold nanorod elastin-like polypeptide matrices were generated and characterized. The matrices were also loaded with the heat-shock protein (HSP)90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), currently in clinical trials for different malignancies, in order to deliver a combination of hyperthermia and chemotherapy. Results: Laser irradiation of cells cultured over the plasmonic matrices (without 17-AAG) resulted in the death of cells directly in the path of the laser, while cells outside the laser path did not show any loss of viability. Such spatial limitations, in concert with expression of prosurvival HSPs, reduce the efficacy of hyperthermia treatment. 17-AAG gold nanorod polypeptide matrices demonstrated minimal leaching of the drug to surrounding media. The combination of hyperthermic temperatures and the release of 17-AAG from the matrix, both induced by laser irradiation, resulted in significant (>90%) death of cancer cells, while 'single treatments' (i.e., hyperthermia alone and 17-AAG alone) demonstrated minimal loss of cancer cell viability (<10%). Conclusion: Simultaneous administration of hyperthermia and HSP inhibitor release from plasmonic matrices is a powerful approach for the ablation of malignant cells and can be extended to different combinations of nanoparticles and chemotherapeutic drugs for a variety of malignancies.