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Experimental studies of tumor immunotherapy. II. Tumor immunotherapy following tumor extirpation.

In order to approach human cancer immunotherapy, the author carried out the immunotherapy with BCG on mice having homotransplanted cancer, observed the posttransplantation results with lapse of time, conduced daily macrophage inhibition test (MI test) and found the immunotherapy to be effective. At the same time the MI test proved to be a useful criterion in determining the course of cancer progress and effectiveness of the immunotherapy.

Animals

Engineering TME-activated CD47-specific CAR macrophage via Arg1 promoter for safe and effective solid tumor immunotherapy.

BACKGROUND: Chimeric antigen receptor macrophage (CAR-Mφ) therapy has promising therapeutic potential in solid tumors, yet challenges remain in target compatibility and systemic toxicity. METHODS: In this study, we screened the CD47-scFv sequence of CAR-Mφ as the extracellular structure. We then constructed a classical CD47 CAR-Mφ incorporated the costimulatory domain of the α1β1 integrin-mediated Fc-gamma receptor I (FcγRI) signaling component. Subsequently, we developed a tumor microenvironment (TME)-responsive CAR macrophage platform by the arginase 1 (Arg1) promoter to target CD47, a highly expressed but clinically challenging immune checkpoint in solid tumors. RESULTS: We found that anti-CD47-scFv-mediated macrophages can effectively kill tumor cells both in vivo and in vitro. Furthermore, by integrating an α1β1 integrin-mediated FcγRI signaling domain, CD47 CAR-Mφ exhibited superior antitumor activity in hCD47+4T1 and SGC-7901 cells in vitro, which demonstrated that the CD47 CAR-Mφ was effective against solid tumors. Subsequently, Arg1-mediated activated pArg1 CD47 CAR-Mφ exhibited strong cytotoxicity against target cancer cells. We further demonstrated TME-controllable CAR gene expression in situ and induced a significant regression of established tumors in vivo. Besides, TME-dependent activation of CD47 CAR Mφ reduced the cytotoxic killing effect on erythrocytes. CONCLUSIONS: Our findings confirmed that the TME-specific activation mechanism of pArg1 CD47 CAR-Mφ based on intrinsic Arg1 promoter reprogramming endowed CAR-Mφ to effectively mitigate erythrocyte toxicity while enabling safe multidose administration regimens. This Trojan horse-like CAR-Mφ system achieves tumor-specific activation while minimizing systemic toxicity, offering a novel strategy to expand CAR-Mφ applications for solid tumors.

Animals

Cell-type specific activation of the cGAS-STING pathway in tumor immunotherapy: mechanisms and therapeutic implications.

BACKGROUND: The cyclic GMP–AMP synthase–stimulator of interferon genes (cGAS–STING) pathway acts as a pivotal innate immune sensor that detects cytosolic DNA and links genomic instability to antitumor immune activation. Therapeutic activation of this pathway has garnered substantial interest as a strategy to enhance cancer immunotherapy by promoting dendritic cell maturation, augmenting antigen presentation, and facilitating cytotoxic lymphocyte infiltration. However, the functional outcomes of cGAS–STING signaling are highly context dependent and influenced by both cell type and tumor microenvironmental (TME) conditions. MAIN BODY: Recent advances in single-cell and spatial transcriptomic profiling have revealed profound heterogeneity in cGAS–STING activation across distinct cellular and regional compartments within tumors. Acute and spatially restricted activation of the pathway can elicit potent antitumor immune responses, whereas chronic or dysregulated signaling may promote immune tolerance and tumor progression. Moreover, metabolic stress, epigenetic silencing, and microenvironmental immunosuppressive factors such as TGF-β and IL-10 can further modulate STING activity, leading to resistance to immunotherapy. Current translational efforts focus on next-generation STING agonists, nanoparticle-based delivery systems, and rational combination strategies with immune checkpoint blockade and metabolic modulators to overcome tumor-intrinsic resistance and minimize systemic toxicity. CONCLUSIONS: Understanding the cell-type-specific and spatial dynamics of cGAS–STING signaling is crucial for the rational design of precision immunotherapies. Future research should emphasize context-dependent modulation of STING activity to maximize therapeutic benefit while limiting adverse effects. Integrating multi-omics technologies and spatially guided drug delivery may ultimately enable personalized modulation of the cGAS–STING axis, transforming it into a clinically effective and safe strategy for cancer immunotherapy.

Humans

Experimental studies of tumor immunotherapy. I. Macrophage migration inhibitory activity as an immunological parameter.

The macrophage migration inhibition activity [MI activity) was stable in sensitized lymphocyte-to-marcophage ratios of 1:5 to 1:20 in mice. Antigen protein concentrations under 100 mug/ml did not induce nonspecific macrophage migration inhibition. Inhibition of tumor proliferation and survival was observed after a combined injection of BCG and MH-134 cells. After a single injection of MH-134 tumor cells, MI activity was reinforced and prolonged, demonstrating the clear effects of BCG as adjuvant. In DDS mice MI activity was weakened in the regional lymph node after a subcutaneous injection of just above or below 10(5) Ehrlich cancer cells previously treated with mitomycin C. This finding suggests the presence of an optimal tumor antigen concentration.

Animals

Tumor immunology and immunotherapy.

Tumor cells contain a variety of antigens, including tumor associated antigens. The tumor associated antigens can be clinically useful as markers for detection of cancer and some may also mediate host resistance against tumor growth. Much emphasis has been placed on the detection of circulating tumor associated markers, with radioimmunoassays for carcinoembryonic antigen (CEA) being extensively utilized. At present, CEA does not appear to be promising for initial detection of cancer, but may find an important place in the determination of prognosis and early detection of recurrent disease. Many cancer patients have depressed immunologic competence, yet they frequently have cell-mediated immunity against tumor associated antigens. Several different immunotherapeutic strategies have been developed, to either augment the immunologic responsiveness of the patient or to specifically increase the immune reactivity against tumor associated transplantation antigens.

Antigens, Neoplasm

PPT1 is a negative regulator of STING signaling in cancer cells and its inhibition reactivates immune surveillance in cold tumors.

Immunotherapy modalities have revolutionized cancer treatment for a number of metastatic and treatment-refractory tumor types. Still, many malignancies that lack T cell infiltration and are termed immunologically "cold" fail to respond to these modalities. One approach to increase tumor immunogenicity has been to induce stimulator of interferon gene (STING) and downstream interferon signaling that is often dysregulated in cold tumors. Despite some early success of STING agonists in preclinical cancer models, these approaches have not been successful in the clinic due to poor tumor penetrance and systemic toxicities. Here, we performed a genome-wide CRISPR screen to uncover therapeutic targets to activate STING expression in human tumors. We identified the lysosomal hydrolase Palmitoyl Protein Thioesterase1 (PPT1) as a negative regulator of STING highly expressed in cold ovarian and prostate tumors. Genetic or pharmacological PPT1 suppression increased STING protein stability and its downstream activation of interferon and inflammatory cytokine signaling to enhance T cell migration. Treatment of preclinical prostate and ovarian cancer models expressing low levels of STING with the small molecule PPT1 inhibitor GNS561 enhanced STING expression and activation, leading to infiltration and activation of cytotoxic T cells that turned these tumors "hot" and reduced tumor growth, fibrosis, and dissemination without toxicity. Further analysis demonstrated that PPT1 is associated with reduced STING expression, CD8+ T cell numbers, overall survival, and immunotherapy outcomes in ovarian and prostate cancer patients. Thus, PPT1 inhibition may be a promising approach to activate STING and potentiate the effects of immunotherapy in cold tumors.

Membrane Proteins

Active specific immunotherapy with tumor cells and Corynebacterium parvum: a phase I study.

Autologous, irradiated (10,000 rads) tumor cells mixed with C. parvum were given as weekly intracutaneous injections to fifteen patients with residual malignant disease. The toxicity was minimal and distinctly less than has been seen with tumor cell-BCG immunotherapy. A goal of 4 injections of 10(7) cells each was possible in only 4 patients because of limitations in methods of disaggregation and quantity of tumor available. The feasibility aspects are discussed and a case report of a prolonged regression is presented.

Adenocarcinoma

Complete regression of a guinea pig hepatocarcinoma by immunotherapy with "tumor-immune" RNA or antibody to fibrin fragment E.

Two novel immunotherapeutic regimens were developed for a uniformly lethal, intradermally growing transplantable ascites variant (line 10) of a diethylnitrosamine-induced hepatoma in strain 2 guinea pigs. In an apparently tumor-specific immunotherapy model, 32 guinea pigs were cured by the injection into the tumor area, five or seven days after tumor challenge, of syngeneic or xenogeneic RNA extracts obtained from lymphoid tissues of line 10-immune strain 2 guinea pigs or rhesus monkeys, as part of a total regimen which included syngeneic nonsensitive peritoneal exudate cells injected prior to, and tumor-specific antigen injected after, the RNA. In another immunotherapy model, not tumor-specific, 18 strain 2 guinea pigs were cured by the injection into the tumor area, 6 and 16 days after tumor challenge, of antibody specific for fibrin fragment E (FFE), an essential component in the formation of a fibrin matrix considered to be important in tumor development. When therapy was delayed to 12 days in the RNA test system, or to 16 days in the anti-FFE test system, complete abrogation of the tumors did not occur. The long-term survival of the 50 successfully treated animals and their immunity to further tumor challenge indicated that both immunotherapeutic procedures had systemic effects. To test this further, line 10 cells were injected intradermally simultaneously at two sites and only one site was treated. When the one tumor location was treated with anti-FFE, complete regression of the treated tumor and a 30% retardation in the development of the untreated tumor were observed. When this tumor location was treated with the RNA regimen, complete regression of the tumors occurred at both the treated and the untreated sites. Optimal conditions for both immunotherapeutic models and their combination have yet to be establshed. Nonetheless, both immunotherapeutic regimens were more effective than any other immunotherapy thus far reported for this tumor, including the use of BCG or its derivatives.

Animals

Abnormalitieis of monocyte chemotaxis in patients with melanoma: effects of immunotherapy and tumor removal.

The chemotactic responsiveness of peripheral blood monocytes was studied before and after immunotherapy was administered to 56 patients with melanoma. Abnormal chemotaxis was found in 36 patients (64%) prior to treatment; this abnormality correlated with severity of disease and prognosis. Immunotherapy with BCG and sensitized autologous lymphocytes and X-irradiated melanoma cells or surgical removal of the neoplasm both reduced the percentage of patients with abnormal chemotactic responses. The best prognosis was found for those patients who had normal chemotaxis prior to therapy. The data support the hypothesis that abnormalities of monocyte function might render the host less likely to destroy developing neoplasms and that malignant tumors themselves might affect monocyte function.

Adolescent

Integration of single-cell transcriptomics and genomic mutation analysis identifies an immunotherapy-resistant tumor subcluster and validates ARNTL2 as a malignant driver in lung adenocarcinoma.

BACKGROUND: Immunotherapy resistance in lung adenocarcinoma (LUAD) remains a critical clinical challenge, and the mechanisms underlying resistance-associated intratumoral heterogeneity are poorly characterized. METHODS: We performed single-cell RNA sequencing of LUAD patients receiving neoadjuvant immunotherapy (responders vs. non-responders), integrating inferCNV, GSVA, and differential expression analyses. Cluster-specific genes were validated across seven independent cohorts (TCGA-LUAD, GSE13213, GSE26939, GSE29016, GSE30219, GSE31210, GSE42127). A multi-algorithm machine learning framework was used to construct a prognostic model, and the immune microenvironment was characterized using TCIA scoring, seven infiltration algorithms, and ESTIMATE. ARNTL2 function was assessed by CCK-8 and Transwell assays in A549 and H1299 cells. RESULTS: Non-responders showed significant enrichment of epithelial cells, depletion of cytotoxic T/NK cells, and elevated copy number variation burden versus responders (p < 0.0001). A resistance-enriched malignant subcluster (Cluster 2) exhibited hyperproliferative and metabolic reprogramming signatures with upregulated KRT17, S100A2, and CST6, which showed tumor-specific overexpression, adverse prognostic value, and genomic amplification across cohorts. CoxBoost combined with survivalSVM achieved optimal predictive performance (C-index = 0.686), yielding robust risk stratification (HR: 2.54-10.51, all p < 0.05). Low-risk patients showed greater immune infiltration and higher TCIA immunophenoscores. ARNTL2 was an independent prognostic factor (HR: 2.07-4.64) strongly correlated with risk score (r = 0.69), and its knockdown suppressed proliferation and invasion in both LUAD cell lines (all p < 0.05). CONCLUSION: This study identifies a resistance-associated malignant subcluster in LUAD, constructs a validated CoxBoost + survivalSVM prognostic model with robust immune stratification, and establishes ARNTL2 as a core oncogenic driver and therapeutic target.

ARNTL2