Combination immunotherapy synergizing the PD-1 blockade with OX40 agonism has become a research hotspot, due to its enormous potential to overcome the restricted clinical objective response suffered by monotherapy. Questions of timing and sequence have been important aspects of immunotherapies when considering immunologic mechanisms; however, most of the time the straightforward additive approach was taken. Herein, our work is the first to investigate an alternative timing of aOX40 and aPD-1 treatment in melanoma-bearing mice, and it demonstrates that sequential administration (aOX40 first, then aPD-1 following) provided superior antitumor benefits than concurrent treatment. Based on that, to further avoid the limits suffered by solution forms, we adopted pharmaceutical technologies to construct an in situ-formed physical-and chemical-dually ROS-responsive nano-in-gel platform to implement sequential and prolonged release of aPD-1 and aOX40. Equipped with these advantages, the as-prepared (aPD-1NCs&aOX40)@Gels elicited augmented combination immunity and achieved great eradication of both primary and distant melanoma tumors in vivo.

With the rapid development of nanotechnology, carrier-based nano-drug delivery systems (DDSs) have been widely studied due to their advantages in optimizing pharmacokinetic and distribution profiles. However, despite those merits, some carrier-related limitations, such as low drug-loading capacity, systematic toxicity and unclear metabolism, usually prevent their further clinical transformation. Carrier-free nanomedicines with non-therapeutic excipients, are considered as an excellent paradigm to overcome these obstacles, owing to their superiority in improving both drug delivery efficacy and safety concern. In recent years, carrier-free nanomedicines have opened new horizons for cancer immunotherapy, and have already made outstanding progress. Herein, in this review, we are focusing on making an integrated and exhaustive overview of lately reports about them. Firstly, the major synthetic strategies of carrier-free nanomedicines are introduced, such as nanocrystals, prodrug-, amphiphilic drug-drug conjugates (ADDCs)-, polymer-drug conjugates-, and peptide-drug conjugates (PepDCs)-assembled nanomedicines. Afterwards, the typical applications of carrier-free nanomedicines in cancer immunotherapy are well-discussed, including cancer vaccines, cytokine therapy, enhancing T-cell checkpoint inhibition, as well as modulating tumor microenvironment (TME). After that, both the advantages and the potential challenges, as well as the future prospects of carrier-free nanomedicines in cancer immunotherapy, were discussed. And we believe that it would be of great potential practiced and reference value to the relative fields.

Immunogenic chemotherapy is a promising approach in cancer treatment, but the number of drugs capable of inducing immunogenic cell death is limited, and chronic immunogenic exposure can delay antitumor immune response and be counteracted by immunosuppressive factors. In this study, we used single-cell and multilevel analyses to highlight the critical importance of the first exposure to calreticulin (CRT) in eliciting immunogenicity. We then developed the ERASION (endoplasmic reticulum (ER) membrane to assist (AS) the presentation of intrinsic onco-immunogenicity (ION)) strategy, leveraging the high expression of functional proteins, including CRT, on the ER membrane. ER membrane-coated liposome (ER@PLip) was able to target the tumor and immune effectors and promoted dendritic cell maturation and T cell infiltration. This enabled eliciting an immunogenic effect from a nonimmunogenic chemotherapeutic drug. By utilizing the ER membrane-associated STING protein, ERASION enabled activating the STING pathway and the generation of adaptive antitumor immunity. This study presents a potential universal platform for integrating traditional chemotherapy and therapeutic modalities.