Extracellular pH modulating injectable gel for enhancing immune checkpoint inhibitor therapy

•NaHCO3 loaded Pluronic F-127 (pHe-MIG) effectively alleviates extracellular tumor acidity.•Neutralization of tumor acidity with pHe-MIG generates immune-favorable tumor microenvironment.•Extracellular acidity impairs CD8+T cell activity through the modulation of immune checkpoint receptors.•pHe-MIG potentiates the efficacy of immune checkpoint inhibitor therapy.