Adenovirus and Oxaliplatin cooperate as agnostic sensitizers for immunogenic cell death in colorectal carcinoma

Advances in therapeutic cancer vaccines: Harnessing immune adjuvants for enhanced efficacy and future perspectives

Preventive cancer vaccines are highly effective in preventing viral infection-induced cancer, but advances in therapeutic cancer vaccines with a focus on eliminating cancer cells through immunotherapy are limited. To develop therapeutic cancer vaccines, the integration of optimal adjuvants is a potential strategy to enhance or complement existing therapeutic approaches. However, conventional adjuvants do not satisfy the criteria of clinical trials for therapeutic cancer vaccines. To improve the effects of adjuvants in therapeutic cancer vaccines, effective vaccination strategies must be formulated and novel adjuvants must be identified. This review offers an overview of the current advancements in therapeutic cancer vaccines and highlights in situ vaccination approaches that can be synergistically combined with other immunotherapies by harnessing the adjuvant effects. Additionally, the refinement of adjuvant systems using cutting-edge technologies and the elucidation of molecular mechanisms underlying immunogenic cell death to facilitate the development of innovative adjuvants have been discussed.

HDAC inhibitors enhance the anti-tumor effect of immunotherapies in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common liver malignancy with a poor prognosis and increasing incidence, remains a serious health problem worldwide. Immunotherapy has been described as one of the ideal ways to treat HCC and is transforming patient management. However, the occurrence of immunotherapy resistance still prevents some patients from benefiting from current immunotherapies. Recent studies have shown that histone deacetylase inhibitors (HDACis) can enhance the efficacy of immunotherapy in a variety of tumors, including HCC. In this review, we present current knowledge and recent advances in immunotherapy-based and HDACi-based therapies for HCC. We highlight the fundamental dynamics of synergies between immunotherapies and HDACis, further detailing current efforts to translate this knowledge into clinical benefits. In addition, we explored the possibility of nano-based drug delivery system (NDDS) as a novel strategy to enhance HCC treatment.

Advantageous Reactivity of Unstable Metal Complexes: Potential Applications of Metal-Based Anticancer Drugs for Intratumoral Injections

Injections of highly cytotoxic or immunomodulating drugs directly into the inoperable tumor is a procedure that is increasingly applied in the clinic and uses established Pt-based drugs. It is advantageous for less stable anticancer metal complexes that fail administration by the standard intravenous route. Such hydrophobic metal-containing complexes are rapidly taken up into cancer cells and cause cell death, while the release of their relatively non-toxic decomposition products into the blood has low systemic toxicity and, in some cases, may even be beneficial. This concept was recently proposed for V(V) complexes with hydrophobic organic ligands, but it can potentially be applied to other metal complexes, such as Ti(IV), Ga(III) and Ru(III) complexes, some of which were previously unsuccessful in human clinical trials when administered via intravenous injections. The potential beneficial effects include antidiabetic, neuroprotective and tissue-regenerating activities for V(V/IV); antimicrobial activities for Ga(III); and antimetastatic and potentially immunogenic activities for Ru(III). Utilizing organic ligands with limited stability under biological conditions, such as Schiff bases, further enhances the tuning of the reactivities of the metal complexes under the conditions of intratumoral injections. However, nanocarrier formulations are likely to be required for the delivery of unstable metal complexes into the tumor.

Immunogenic Cell Death-Based Cancer Vaccines

Cancer immunotherapy has achieved great advancement in the past decades. Whereas, its response is largely limited in immunologically cold tumors, in an urgent need to be solve. In recent years, an increasing number of studies have shown that inducing immunogenic cell deaths (ICDs) is an attractive approach to activate antitumor immunity. Upon specific stress, cancer cells undergo ICDs and dying cancer cells release danger associated molecular patterns (DAMPs), produce neoantigens and trigger adaptive immunity. ICDs exert a cancer vaccine-like effect and Inducement of ICDs mimics process of cancer vaccination. In this review, we propose a concept of ICD-based cancer vaccines and summarize sources of ICD-based cancer vaccines and their challenges, which may broaden the understandings of ICD and cancer vaccines in cancer immunotherapy.

Inhibition of indoleamine 2,3-dioxygenase 1 synergizes with oxaliplatin for efficient colorectal cancer therapy

We investigated the immunogenic cell death provoked by oxaliplatin (OXA) and the involvement of OXA-induced immunosuppression in colorectal cancer. Immune-proficient or -deficient mice were employed to evaluate the therapeutic effects of OXA. Immunogenic cell death was characterized by cell-surface calreticulin, cytosol-translocated high migration rate group protein B1 (HMGB1), and secretory ATP content. Bone marrow-derived dendritic cell (BMDC) maturation and CD8+ T cell expansion were measured by flow cytometry. Expression of immunosuppressive genes was quantified by both RT-PCR and western blots. The proliferative and apoptotic indexes of xenograft tumors were evaluated by immunohistochemistry and TUNEL assays, respectively. The secretory cytokines were measured with ELISA. OXA induced immunogenic cell death of murine colorectal cancer, which greatly depended on the host immune response. OXA-pretreated CT26 cells promoted BMDC maturation and CD8+ T cell expansion. OXA significantly upregulated indoleamine 2,3-dioxygenase 1 (IDO1) in patient-derived colorectal cancer cells and in combination with the IDO1-specific inhibitor, NLG919, suppressed tumor progression. Simultaneous administration with both OXA and NLG919 greatly promoted CD8+ T cell infiltration and decreased immunosuppressive cytokine transforming growth factor β (TGF-β) production, whereas increased immunostimulatory cytokines interleukin (IL)-12p70 and interferon (IFN)-γ. We demonstrated the upregulation of IDO1 by OXA, which combined with the IDO1 inhibitor, tremendously potentiated therapeutic effects of OXA against colorectal cancer.

Nanomedicine-mediated induction of immunogenic cell death and prevention of PD-L1 overexpression for enhanced hepatocellular carcinoma therapy

Background

The present study aims to develop a nanoparticle encapsulating doxorubicin (DOX) and programmed death-ligand 1 (PD-L1) siRNA and evaluate its anti-tumor effects on hepatoma carcinoma (HCC).

Methods

Nanoparticle encapsulating DOX and PD-L1 siRNA (NPDOX/siPD-L1) was characterized by dynamic light scattering and transmission electron microscopy. Flow cytometry was applied to analyze cell populations, NPDOX/siPD-L1 internalization, and cell apoptosis. Real-Time (RT)-quantitative reverse transcription (qPCR) and western blotting were used to determine the mRNA and protein levels, respectively. Released ATP was determined using ATP determination kit and cytokines were determined using specific ELISAs. A tumor-bearing animal model was established to evaluate the anti-tumor effects of NPDOX/siPD-L1.

Results

Treatment of NPDOX/siPD-L1 induced immunogenic cell death (ICD) and PD-L1 overexpression in HCC. In vivo study demonstrated that intravenously injection of NPDOX/siPD-L1 significantly inhibited the tumor volume and PD-L1 expressions of tumor tissue in the H22 tumor-bearing animal model. Besides, the treatment of NPDOX/siPD-L1 also regulated the populations of matured dendritic cells and cytotoxic T cells and the productions of cytokines in the tumor tissues.

Conclusion

Taken together, NPDOX/siPD-L1 showed significant anti-tumor effects on HCC by the induction of ICD and inhibition of PD-L1 overexpression.

T cell recruitment triggered by optimal dose platinum compounds contributes to the therapeutic efficacy of sequential PD-1 blockade in a mouse model of colon cancer

Recently, the combination of platinum chemotherapy with PD-1/PD-L1 pathway blockades has shown synergistic efficacy in a few clinical trials. However, the exact mechanisms and the optimized sequence of such combinations are not fully clear. In this study, we combined different doses of platinum agents (cisplatin or oxaliplatin) with sequential therapy of PD-1 blockade therapy (anti-PD-1 antibody or anti-PD-L1 antibody) to treat established MC38 murine colon tumors. Although 10 mg/kg platinum (cisplatin or oxaliplatin) showed no significant effect on tumor growth, its combination with sequential anti-PD-1 antibody administration caused complete tumor remission in 80-100% mice. The synergic therapeutic efficacy was found to be associated with more effector and less exhausted CD8 T cell infiltration in the tumor sites. Platinum chemotherapy is generally considered immunosuppressive, with lymphopenia and neutropenia being common side effects. However, our data showed that high-dose (20 mg/kg) platinum treatment induced lymphopenia in MC38 tumor-bearing mice, and low-dose (10 mg/kg) treatment augmented the T cell response with an increased number of peripheral T cells. Notably, increased numbers of PD-1 positive CD8 T cells were found in draining lymph nodes, peripheral blood and tumor tissues three days after 10 mg/kg oxaliplatin treatment, and increased numbers of CD8 T cells and apoptotic tumor cells were detected at the edge of tumor tissues. Further investigation showed that the death of tumor cells induced by platinum compounds promoted T cell activation. Moreover, increased expression of T cell-attracting chemokines (CXCL9, CXCL10 and CCL5) was detected in MC38 cells after platinum treatment. These data indicated that the optimal dose of platinum chemotherapy could trigger T cell activation and recruitment into tumors, and sequential PD-1 blockade could prevent newly arriving T cell from becoming exhausted in tumor sites. These findings highlight the importance of optimizing the dose and timing of platinum chemotherapy combined with PD-1 blockade and provide an indication for the improvement of combined therapies in clinical trials.