Another benefit of dietary fiber The gut microbiome can modulate the immune system and influence the therapeutic response of cancer patients, yet the mechanisms underlying the effects of microbiota are presently unclear. Spencer et al . add to our understanding of how dietary habits affect microbiota and clinical outcomes to immunotherapy. In an observational study, the researchers found that melanoma patients reporting high fiber (prebiotic) consumption had a better response to checkpoint inhibitor immunotherapy compared with those patients reporting a low-fiber diet. The most marked benefit was observed for those patients reporting a combination of high fiber consumption and no use of over-the-counter probiotic supplements. These findings provide early insights as to how diet-related factors may influence the immune response. —PNK

Most ovarian cancer patients respond well to initial platinum-based chemotherapy. However, within a year, many patients experience disease recurrence with a platinum resistant phenotype that responds poorly to second line chemotherapies. As a result, new strategies to address platinum resistant ovarian cancer (PROC) are needed. Herein, we report that NP co-delivery of cisplatin (CP) and wortmannin (Wtmn), a DNA repair inhibitor, synergistically enhances chemoradiotherapy (CRT) and reverses CP resistance in PROC. We encapsulated this regimen in FDA approved poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) NPs to reduce systemic side effects, enhance cellular CP uptake, improve Wtmn stability, and increase therapeutic efficacy. Treatment of platinum-sensitive ovarian cancer (PSOC) and PROC murine models with these dual-drug loaded NPs (DNPs) significantly reduced tumor burden versus treatment with combinations of free drugs or single-drug loaded NPs (SNPs). These results support further investigation of this NP-based, synergistic drug regimen as a means to combat PROC in the clinic.

BackgroundType 1 conventional dendritic cells (cDC1s) possess efficient antigen presentation and cross-presentation activity, as well as potent T cell priming ability. Tissue-resident cDC1s (CD103+cDC1s in mice, CD141+cDC1s in humans) are linked with improved tumor control, yet the efficacy of immunotherapy using this population is understudied.MethodsWe generated murine CD103+cDC1s in vitro and examined their expression of cDC1-related factors, antigen cross-presentation activity, and accumulation in tumor-draining lymph nodes (TdLNs). The antitumor efficacy of the in vitro-generated CD103+cDC1s was studied in murine melanoma and osteosarcoma models. We evaluated tumor responses on vaccination with CD103+cDC1s, compared these to vaccination with monocyte-derived DCs (MoDCs), tested CD103+cDC1 vaccination with checkpoint blockade, and examined the antimetastatic activity of CD103+cDC1s.ResultsIn vitro-generated CD103+cDC1s produced cDC1-associated factors such as interleukin-12p70 and CXCL10, and demonstrated antigen cross-presentation activity on stimulation with the toll-like receptor 3 agonist polyinosinic:polycytidylic acid (poly I:C). In vitro-generated CD103+cDC1s also migrated to TdLNs following poly I:C treatment and intratumoral delivery. Vaccination with poly I:C-activated and tumor antigen-loaded CD103+cDC1s enhanced tumor infiltration of tumor antigen-specific and interferon-γ+CD8+T cells, and suppressed melanoma and osteosarcoma growth. CD103+cDC1s showed superior antitumor efficacy compared with MoDC vaccination, and led to complete regression of 100% of osteosarcoma tumors in combination with CTLA-4 antibody-mediated checkpoint blockade. In vitro-generated CD103+cDC1s effectively protected mice from pulmonary melanoma and osteosarcoma metastases.ConclusionsOur data indicate an in vitro-generated CD103+cDC1 vaccine elicits systemic and long-lasting tumor-specific T cell-mediated cytotoxicity, which restrains primary and metastatic tumor growth. The CD103+cDC1 vaccine was superior to MoDCs and enhanced response to immune checkpoint blockade. These results indicate the potential for new immunotherapies based on use of cDC1s alone or in combination with checkpoint blockade.

Immune checkpoint blockade (ICB) has revolutionized cancer treatment, yet quality of life and continuation of therapy can be constrained by immune-related adverse events (irAEs). Limited understanding of irAE mechanisms hampers development of approaches to mitigate their damage. To address this, we examined whether mice gained sensitivity to anti-CTLA-4 (αCTLA-4)–mediated toxicity upon disruption of gut homeostatic immunity. We found αCTLA-4 drove increased inflammation and colonic tissue damage in mice with genetic predisposition to intestinal inflammation, acute gastrointestinal infection, transplantation with a dysbiotic fecal microbiome, or dextran sodium sulfate administration. We identified an immune signature of αCTLA-4–mediated irAEs, including colonic neutrophil accumulation and systemic interleukin-6 (IL-6) release. IL-6 blockade combined with antibiotic treatment reduced intestinal damage and improved αCTLA-4 therapeutic efficacy in inflammation-prone mice. Intestinal immune signatures were validated in biopsies from patients with ICB colitis. Our work provides new preclinical models of αCTLA-4 intestinal irAEs, mechanistic insights into irAE development, and potential approaches to enhance ICB efficacy while mitigating irAEs.

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease that results from autoreactive T cells destroying insulin‐producing pancreatic beta (β) cells. The development of T1DM is associated with the deficiency of co‐inhibitory immune checkpoint ligands (e.g., PD‐L1, CD86, and Gal‐9) in β cells. Here, a new translational approach based on metabolic glycoengineering and bioorthogonal click chemistry, which bioengineers β cells with co‐inhibitory immune checkpoint molecules that induce antigen‐specific immunotolerance and reverse early‐onset hyperglycemia is reported. To achieve this goal, a subcutaneous injectable acellular pancreatic extracellular matrix platform for localizing the bioengineered β cells while creating a pancreas‐like immunogenic microenvironment, in which the autoreactive T cells can interface with the β cells, is devised.

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Hepatotoxicity is a key concern in the clinical translation of nanotherapeutics because preclinical studies have consistently shown that nanotherapeutics accumulates extensively in the liver. However, clinical‐stage nanotherapeutics have not shown increased hepatotoxicity. Factors that can contribute to the hepatotoxicity of nanotherapeutics beyond the intrinsic hepatotoxicity of nanoparticles (NPs) are poorly understood. Because of this knowledge gap, clinical translation efforts have avoided hepatotoxic molecules. By examining the hepatotoxicity of nanoformulations of known hepatotoxic compounds, it is demonstrated that nanotherapeutics are associated with lower hepatotoxicity than their small‐molecule counterparts. It is also found that the reduced hepatotoxicity is related to the uptake of nanotherapeutics by macrophages in the liver. These findings can facilitate further development and clinical translation of nanotherapeutics.