Rational administration sequencing of immunochemotherapy elicits powerful anti-tumor effect

As a research hotspot, immune checkpoint inhibitors (ICIs) is often combined with other therapeutics in order to exert better clinical efficacy. To date, extensive laboratory and clinical investigations into the combination of ICIs and chemotherapy have been carried out, demonstrating augmented effectiveness and broad application prospects in anti-tumor therapy. However, the administration of these two treatment modalities is usually randomized or fixed to a given chronological order. Nevertheless, the pharmacological effect of drug is closely related to its exposure behavior in vivo, which may consequently affect the synergistic outcomes of a combined therapy. In this study, we prepared a lipid nanoparticle encapsulating docetaxel (DTX-VNS), and associated it with the immune checkpoint inhibitor anti-PD-1 antibody (αPD-1) for the treatment of malignant tumors. To identify the optimum timing and sequencing for chemotherapy and immunotherapy, we designed three administration regimes, including the simultaneous delivery of DTX-VNS and αPD-1(DTX-VNS@αPD-1), DTX-VNS delivery before (DTX-VNS plus αPD-1) or post (αPD-1 plus DTX-VNS) PD-1 blockade with an interval of two days. Analysis from mass spectrometry, multi-factor detection and other techniques indicated that DTX-VNS plus αPD-1 initiated a powerful anti-tumor response in multiple tumor models, contributing to a remarkably reshaped tumor microenvironment landscape, which may attribute to the maximum therapeutic additive effects arise from a concomitant exposure of DTX-VNS and αPD-1 at the tumor site. By profiling the exposure kinetics of nanoparticles and αPD-1 in vivo, we defined the administration schedule with utmost therapeutic benefits, which may provide a valuable clinical reference for the rational administration of immunochemotherapy.