Self-assembled FeS-based cascade bioreactor with enhanced tumor penetration and synergistic treatments to trigger robust cancer immunotherapy

Abstract

Major challenges for cancer treatment are how to effectively eliminate primary tumor and sufficiently induce immunogenic cell death (ICD) to provoke a robust immune response for metastasis control. Here, a self-assembled cascade bioreactor was developed to improve cancer treatment with enhanced tumor penetration and synergistic therapy of starvation, chemodynamic (CDT) and photothermal therapy. Ultrasmall FeS-GOx nanodots were synthesized with glucose oxidase (GOx) as template and induced by paclitaxel (PTX) to form self-assembling FeS-GOx@PTX (FGP) via hydrophobic interaction. After accumulated at tumor sites, FGP disassembles to smaller FeS-GOx for enhanced deep tumor penetration. GOx maintains high enzymatic activity to catalyze glucose with assistant of oxygen to generate hydrogen peroxide (H₂O₂) as starvation therapy. Fenton reaction involving the regenerated H₂O₂ in turn produced more hydroxyl radicals for enhanced CDT. Following near-infrared laser at 808 nm, FGPs displayed pronounced tumor inhibition in vitro and in vivo by the combination therapy. The consequent increased exposure to calreticulin amplified ICD and promoted dendritic cells maturation. In combination with anti-CTLA4 checkpoint blockade, FGP can absolutely eliminate primary tumor and avidly inhibit distant tumors due to the enhanced intratumoral infiltration of cytotoxic T lymphocytes. Our work presents a promising strategy for primary tumor and metastasis inhibition.

Keywords: ALP, alkaline phosphatise; ALT, alanine transaminase; AST, aspartate aminotransferase; ATP, adenosine triphosphate; BUN, blood urea nitrogen; CDT, chemodynamic therapy; CLSM, confocal laser scanning microscope; CREA, creatinine; CRT, calreticulin; CTLA-4, cytotoxic T-lymphocyte-associated protein 4; CTLs, cytotoxic T lymphocytes; Cancer immunotherapy; Ce6, Chlorin e6; DAMPs, damage-related molecular patterns; DAPI, 2-(4-amidinophenyl)-6-indolecarbamidine dihydrochloride; DCs, dendritic cells; DLS, dynamic light scattering; DMPO, dimethyl pyridine N-oxide; EDC, 1-ethyl-3-(3ʹ-dimethylaminopropyl) carbodiimide; EDS, energy-dispersive spectrometry; EPR, enhanced permeability and retention; ESR, electron spin resonance; FG, FeS-GOx nanodots; FGP, FeS-GOx@PTX nanoparticles; FITC, fluorescein Isothiocyanate; FeCl2·4H2O, iron dichloride tetrahydrate; FeS-based cascade bioreactor; GOx, glucose oxidase; Glu, glucose; Glucose oxidase; H&E, hematoxylin and eosin; H2DCFDA, 2,7-dichlorodihydrofluorescein acetoacetic acid; HMGB-1, high mobility group box protein 1; HPF, 2-[6-(4,-hydroxy) phenoxy-3H-xanthene-3-on-9-yl; HSA, human serum albumin; ICB, immune checkpoint blockade; ICD amplifier; ICD, immunogenic cell death; IFN-γ, interferon-γ; MB, methylene blue; MCTS, multicellular tumor spheroids; MFI, median fluorescence Intensity; Metastasis inhibition; NHS, N-hydroxy succinimide; Na2S, sodium sulfide; OH, hydroxyl; PBS, phosphate buffer saline; PTT, photothermal therapy; PTX, paclitaxel; ROS, reactive oxygen species; SEM, scanning electron microscope; Synergistic therapy; TAA, tumor-associated antigens; TDLN, tumor-draining lymph nodes; TEM, transmission microscope; TMB, 3,3ʹ,5,5ʹ-tetramathylbenzidine; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labelling; Tumor penetration; XPS, X-ray photoelectron spectroscopy; XRD, X-ray diffraction patterns.