Neoadjuvant STING Activation, Extended Half-life IL2, and Checkpoint Blockade Promote Metastasis Clearance via Sustained NK-cell Activation.

Combination immunotherapy treatments that recruit both innate and adaptive immunity have the potential to increase cancer response rates by engaging a more complete repertoire of effector mechanisms. Here, we combined intratumoral STimulator of INterferon Genes (STING) agonist therapy with systemically injected extended half-life IL2 and anti-PD-1 checkpoint blockade (hereafter CIP therapy) to drive innate and adaptive antitumor immunity in models of triple-negative breast cancer. Unlike treatment with the individual components, this trivalent immunotherapy halted primary tumor progression and led to long-term remission for a majority of animals in two spontaneously metastasizing orthotopic breast tumor models, though only as a neoadjuvant therapy but not adjuvant therapy. CIP therapy induced antitumor T-cell responses, but protection from metastatic relapse depended on natural killer (NK) cells. The combination of STING agonists with IL2/anti-PD-1 synergized to stimulate sustained granzyme and cytokine expression by lung-infiltrating NK cells. Type I IFNs generated as a result of STING agonism, combined with IL2, acted in a positive-feedback loop by enhancing the expression of IFNAR-1 and CD25 on lung NK cells. These results suggest that NK cells can be therapeutically targeted to effectively eliminate tumor metastases.See related Spotlight by Demaria, p. 3.

Enhanced CAR-T cell activity against solid tumors by vaccine boosting through the chimeric receptor.

Chimeric antigen receptor-T cell (CAR-T) therapy has been effective in the treatment of hematologic malignancies, but it has shown limited efficacy against solid tumors. Here we demonstrate an approach to enhancing CAR-T function in solid tumors by directly vaccine-boosting donor cells through their chimeric receptor in vivo. We designed amphiphile CAR-T ligands (amph-ligands) that, upon injection, trafficked to lymph nodes and decorated the surfaces of antigen-presenting cells, thereby priming CAR-Ts in the native lymph node microenvironment. Amph-ligand boosting triggered massive CAR-T expansion, increased donor cell polyfunctionality, and enhanced antitumor efficacy in multiple immunocompetent mouse tumor models. We demonstrate two approaches to generalizing this strategy to any chimeric antigen receptor, enabling this simple non-human leukocyte antigen-restricted approach to enhanced CAR-T functionality to be applied to existing CAR-T designs.

Enhancing humoral immunity via sustained-release implantable microneedle patch vaccination.

Sustained exposure of lymphoid tissues to vaccine antigens promotes humoral immunity, but traditional bolus immunizations lead to rapid antigen clearance. We describe a technology to tailor vaccine kinetics in a needle-free platform translatable to human immunization. Solid pyramidal microneedle (MN) arrays were fabricated with silk fibroin protein tips encapsulating a stabilized HIV envelope trimer immunogen and adjuvant, supported on a dissolving polymer base. Upon brief skin application, vaccine-loaded silk tips are implanted in the epidermis/upper dermis where they release vaccine over a time period determined by the crystallinity of the silk matrix. Following MN immunization in mice, Env trimer was released over 2 wk in the skin, correlating with increased germinal center (GC) B cell responses, a ∼1,300-fold increase in serum IgG titers and a 16-fold increase in bone marrow (BM) plasma cells compared with bolus immunization. Thus, implantable MNs provide a practical means to substantially enhance humoral immunity to subunit vaccines.

Cell and fluid sampling microneedle patches for monitoring skin-resident immunity.

Important cell populations reside within tissues and are not accessed by traditional blood draws used to monitor the immune system. To address this issue at an essential barrier tissue, the skin, we created a microneedle-based technology for longitudinal sampling of cells and interstitial fluid, enabling minimally invasive parallel monitoring of immune responses. Solid microneedle projections were coated by a cross-linked biocompatible polymer, which swells upon skin insertion, forming a porous matrix for local leukocyte infiltration. By embedding molecular adjuvants and specific antigens encapsulated in nanocapsules within the hydrogel coating, antigen-specific lymphocytes can be enriched in the recovered cell population, allowing for subsequent detailed phenotypic and functional analysis. We demonstrate this approach in mice immunized with a model protein antigen or infected in the skin with vaccinia virus. After vaccination or infection, sampling microneedles allowed tissue-resident memory T cells (TRMs) to be longitudinally monitored in the skin for many months, during which time the antigen-specific T cell population in systemic circulation contracted to low or undetectable counts. Sampling microneedles did not change the immune status of naïve or antigen-exposed animals. We also validated the ability of cell sampling using human skin samples. This approach may be useful in vaccines and immunotherapies to temporally query TRM populations or as a diagnostic platform to sample for biomarkers in chronic inflammatory and autoimmune disorders, allowing information previously accessible only via invasive biopsies to be obtained in a minimally invasive manner from the skin or other mucosal tissues.