Injectable thermo-sensitive hydrogel enhances anti-tumor potency of engineered Lactococcus lactis by activating dendritic cells and effective memory T cells.

Engineered bacteria have shown great potential in cancer immunotherapy by dynamically releasing therapeutic payloads and inducing sustained antitumor immune response with the crosstalk of immune cells. In previous studies, FOLactis was designed, which could secret an encoded fusion protein of Fms-related tyrosine kinase 3 ligand and co-stimulator OX40 ligand, leading to remarkable tumor suppression and exerting an abscopal effect by intratumoral injection. However, it is difficult for intratumoral administration of FOLactis in solid tumors with firm texture or high internal pressure. For patients without lesions such as abdominal metastatic tumors and orthotopic gastric tumors, intratumoral injection is not feasible and peritumoral maybe a better choice. Herein, an engineered bacteria delivery system is constructed based on in situ temperature-sensitive poloxamer 407 hydrogels. Peritumoral injection of FOLactis/P407 results in a 5-fold increase in the proportion of activated DC cells and a more than 2-fold increase in the proportion of effective memory T cells (TEM), playing the role of artificial lymph island. Besides, administration of FOLactis/P407 significantly inhibits the growth of abdominal metastatic tumors and orthotopic gastric tumors, resulting in an extended survival time. Therefore, these findings demonstrate the delivery approach of engineered bacteria based on in situ hydrogel will promote the efficacy and universality of therapeutics.

Engineered lactococcus lactis intrapleural therapy promotes regression of malignant pleural effusion by enhancing antitumor immunity.

Intrapleural immunotherapies have emerged as a prominent field in treating malignant pleural effusion (MPE). Among these, bacteria-based intrapleural therapy has exerted an anti-MPE effect by immuno-stimulating or cytotoxic properties. We previously engineered a probiotic Lactococcus lactis (FOLactis) expressing a fusion protein of Fms-like tyrosine kinase 3 and co-stimulator OX40 ligands. FOLactis activates tumor antigen-specific immune responses and displays systemic antitumor efficacy via intratumoral delivery. However, no available lesions exist in the pleural cavity of patients with MPE for intratumoral administration. Therefore, we further optimize FOLactis to treat MPE through intrapleural injection. Intrapleural administration of FOLactis (I-Pl FOLactis) not only distinctly suppresses MPE and pleural tumor nodules, but also significantly extends noticeable survival in MPE-bearing murine models. The proportion of CD103+ dendritic cells (DCs) in tumor-draining lymph nodes increases three-fold in FOLactis group, compared to the wild-type bacteria group. The enhanced DCs recruitment promotes the infiltration of effector memory T and CD8+ T cells, as well as the activation of NK cells and the polarization of macrophages to M1. Programmed death 1 blockade antibody combination further enhances the antitumor efficacy of I-Pl FOLactis. In summary, we first develop an innovative intrapleural strategy based on FOLactis, exhibiting remarkable efficacy and favorable biosafety profiles. These findings suggest prospective clinical translation of engineered probiotics for managing MPE through direct administration into the pleural cavity.

Intra-bone marrow injection with engineered Lactococcus lactis for the treatment of metastatic tumors: Primary report.

Bone marrow has the capacity to produce different types of immune cells, such as natural killer cells, macrophages, dendritic cells (DCs) and T cells. Improving the activation of immune cells in the bone marrow can enhance the therapy of bone metastases. Previously, we designed an engineered probiotic Lactococcus lactis, capable of expressing a fusion protein of Fms-like tyrosine kinase 3 ligand and co-stimulator OX40 ligand (FOLactis), and proved that it can induce the activation and differentiation of several immune cells. In this research, we successfully establish mouse models of bone metastasis, lung metastasis and intraperitoneal dissemination, and we are the first to directly inject the probiotics into the bone marrow to inhibit tumor growth. We observe that injecting FOLactis into the bone marrow of mice can better regulate the immune microenvironment of tumor-bearing mice, resulting in a tumor-suppressive effect. Compared to subcutaneous (s.c.) injection, intra-bone marrow (IBM) injection is more effective in increasing mature DCs and CD8+ T cells and prolonging the survival of tumor-bearing mice. Our results confirm that IBM injection of FOLactis reprograms the immune microenvironment of bone marrow and has remarkable effectiveness in various metastatic tumor models.

Design of a single-center, phase II trial to explore the efficacy and safety of 'R-ISV-RO' treatment in advanced tumors.

Background: The authors' preclinical study has confirmed that RO adjuvant (composed of TLR 7 agonists [imiquimod/R837] and OX40 agonists) injected into local lesions induces the regression of both primary tumor and distant metastasis. The authors propose to realize local control and exert abscopal effect through an 'R-ISV-RO' in situ strategy plus anti-PD-1 monoclonal antibody in advanced tumors. Methods: This study is a single-center, exploratory, phase II trial to evaluate the efficacy and safety of R-ISV-RO plus anti-PD-1 monoclonal antibody in advanced tumors. 30 patients with one or more measurable extracerebral lesions that are accessible for radiation or injection will be enrolled. The primary endpoint is the objective response rate of target lesions. Discussion/Conclusion: The efficacy and safety of the novel strategy will be further validated through this clinical trial. Clinical trial registration: ChiCTR2100053870 (www.chictr.org.cn/).

A Thermosensitive Bi-Adjuvant Hydrogel Triggers Epitope Spreading to Promote the Anti-Tumor Efficacy of Frameshift Neoantigens.

Tumor-specific frameshift mutations encoding peptides (FSPs) are highly immunogenic neoantigens for personalized cancer immunotherapy, while their clinical efficacy is limited by immunosuppressive tumor microenvironment (TME) and self-tolerance. Here, a thermosensitive hydrogel (FSP-RZ-BPH) delivering dual adjuvants R848 (TLR7/8 agonist) + Zn2+ (cGAS-STING agonist) is designed to promote the efficacy of FSPs on murine forestomach cancer (MFC). After peritumoral injection, FSP-RZ-BPH behaves as pH-responsive sustained drug release at sites near the tumor to effectively transform the immunosuppressive TME into an inflammatory type. FSP-RZ-BPH orchestrates innate and adaptive immunity to activate dendritic cells in tumor-draining lymph nodes and increase the number of FSPs-reactive effector memory T cells (TEM) in tumor by 2.9 folds. More importantly, these TEM also exhibit memory responses to nonvaccinated neoantigens on MFC. This epitope spreading effect contributes to reduce self-tolerance to maintain long-lasting anti-tumor immunity. In MFC suppressive model, FSP-RZ-BPH achieves 84.8% tumor inhibition rate and prolongs the survival of tumor-bearing mice with 57.1% complete response rate. As a preventive tumor vaccine, FSP-RZ-BPH can also significantly delay tumor growth. Overall, the work identifies frameshift MFC neoantigens for the first time and demonstrates the thermosensitive bi-adjuvant hydrogel as an effective strategy to boost bystander anti-tumor responses of frameshift neoantigens.

Membrane fusogenic nanoparticle-based HLA-peptide-addressing universal T cell receptor-engineered T (HAUL TCR-T) cell therapy in solid tumor.

T cell receptor-engineered T (TCR-T) cell therapy has demonstrated therapeutic effects in basic research and clinical trials for treating solid tumors. Due to the peptide-dependent recognition and the human leukocyte antigen (HLA)-restriction, TCR-T cell therapy is generally custom designed to target individual antigens. The lack of suitable universal targets for tumor cells significantly limits its clinical applications. Establishing a universal TCR-T treatment strategy is of great significance. This study designed and evaluated the HLA-peptide-addressing universal (HAUL) TCR-T cell therapy based on HLA-peptide (pHLA) loaded membrance fusogenic deliver system. The pHLA-NP-based tumor cell membrane modification technology can transfer the pHLA onto the surface of tumor cells through membrane fusogenic nanoparticles. Then tumor cells are recognized and killed by TCR-T cells specifically. The HAUL TCR-T cell therapy technology is a universal technology that enables tumor cells to be identified and killed by specific TCR-T cells, regardless of the HLA typing of tumor cells.

Enhanced systemic tumor suppression by in situ vaccine combining radiation and OX40 agonist with CpG therapy.

BACKGROUND: In situ tumor vaccine has been gradually becoming a hot research field for its advantage of achieving personalized tumor therapy without prior antigen identification. Various in situ tumor vaccine regimens have been reported to exert considerable antitumor efficacy in preclinical and clinical studies. However, the design of in situ tumor vaccines still needs further optimization and the underlying immune mechanism also waits for deeper investigation. METHODS: A novel triple in situ vaccine strategy that combining local radiation with intratumoral injection of TLR9 agonist CpG and OX40 agonist was established in this sturdy. Local and abscopal antitumor efficacy as well as survival benefit were evaluated in the bilateral tumors and pulmonary metastasis model of B16F10 melanoma. In situ vaccine-induced immune responses and immune-associated variation in tumor environment were further investigated using multiparameter flow cytometry and RNA sequencing. Base on the analysis, the RT + CpG + αOX40 triple in situ vaccine was combined with checkpoint blockade therapy to explore the potential synergistic antitumor efficacy. RESULTS: Enhanced tumor suppression was observed with minimal toxicity in both treated and untreated abscopal tumors after receiving RT + CpG + αOX40 triple vaccine. The introduction of local radiation and OX40 agonist benefit more to the inhibition of local and abscopal lesions respectively, which might be partially attributed to the increase of effector memory T cells in the tumor microenvironment. Further analysis implied that the triple in situ vaccine did not only activate the microenvironment of treated tumors, with the upregulation of multiple immune-associated pathways, but also enhanced systemic antitumor responses, thus achieved superior systemic tumor control and survival benefit. Moreover, the triple in situ vaccine synergized with checkpoint blockade therapy, and significantly improved the therapeutic effect of anti-programmed cell death protein (PD)-1 antibody. CONCLUSION: This triple combining in situ vaccine induced intensive antitumor responses, mediated effective systemic tumor control and survival benefit, and displayed impressive synergistic antitumor effect with checkpoint blockade therapy. These data preliminary confirmed the efficacy, feasibility and safety of the triple combining in situ vaccine, suggesting its great application potential as both monotherapy and a part of combined immunotherapeutic regimens in clinical scenario.

Engineered Lactococcus lactis secreting Flt3L and OX40 ligand for in situ vaccination-based cancer immunotherapy.

In situ vaccination is a promising strategy to convert the immunosuppressive tumor microenvironment into an immunostimulatory one with limited systemic exposure and side effect. However, sustained clinical benefits require long-term and multidimensional immune activation including innate and adaptive immunity. Here, we develop a probiotic food-grade Lactococcus lactis-based in situ vaccination (FOLactis) expressing a fusion protein of Fms-like tyrosine kinase 3 ligand and co-stimulator OX40 ligand. Intratumoural delivery of FOLactis contributes to local retention and sustained release of therapeutics to thoroughly modulate key components of the antitumour immune response, such as activation of natural killer cells, cytotoxic T lymphocytes, and conventional-type-1-dendritic cells in the tumors and tumor-draining lymph nodes. In addition, intratumoural administration of FOLactis induces a more robust tumor antigen-specific immune response and superior systemic antitumour efficacy in multiple poorly immune cell-infiltrated and anti-PD1-resistant tumors. Specific depletion of different immune cells reveals that CD8+ T and natural killer cells are crucial to the in situ vaccine-elicited tumor regression. Our results confirm that FOLactis displays an enhanced antitumour immunity and successfully converts the 'cold' tumors to 'hot' tumors.

Neoantigen-targeted TCR-T cell therapy for solid tumors: How far from clinical application.

T cell receptor-engineered T (TCR-T) cells targeting neoantigens present potential immunotherapy for solid tumors. With the continuous optimization of the entire production procedures, the manufacturing process of TCR-T cells is becoming more efficient and productive. However, clinical-scale manufacturing of TCR-T cells still encounters tremendous challenges. Here, we summarize the latest progress of neoantigen-targeted TCR-T cell therapy and focus on the technical difficulties in preparing personalized neoantigen-targeted TCR-T cells and the challenges in clinical applications. Possible approaches for improving TCR-T cell therapy are discussed as well in this review.

In situ vaccine: new ideas for tumor immunotherapy / 中国肿瘤生物治疗杂志

@#肿瘤免疫治疗的新策略发展迅速，已经成为肿瘤治疗最受瞩目的领域。关于如何实现最理想抗肿瘤免疫效果，可采 用“被动”免疫疗法如过继性细胞疗法、基因工程T细胞等直接攻击肿瘤细胞，也可采用“主动”免疫疗法如细胞因子、肿瘤疫苗、 免疫检查点抑制剂等调节并激活免疫系统。原位疫苗以局部瘤内注射的方式， 将“主动”和“被动”免疫科学地结合起来，在直接 抑制肿瘤细胞的同时深度调节和触发机体免疫系统，形成免疫启动-免疫效应-肿瘤细胞死亡-抗原释放导致免疫再启动-免疫再 效应的反复循环，最大限度地发挥抗肿瘤免疫效果。本文就原位疫苗的具体策略、临床前研究和临床试验的进展，以及原位疫苗 的优势、存在问题和应对策略等展开讨论。