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Boiling histotripsy and in-situ CD40 stimulation improve the checkpoint blockade therapy of poorly immunogenic tumors.

ABSTRACT: Background: Advanced stage cancers with a suppressive tumor microenvironment (TME) are often refractory to immune checkpoint inhibitor (ICI) therapy. Recent studies have shown that focused ultrasound (FUS) TME-modulation can synergize ICI therapy, but enhancing survival outcomes in poorly immunogenic tumors remains challenging. Here, we investigated the role of focused ultrasound based boiling histotripsy (HT) and in-situ anti-CD40 agonist antibody (αCD40) combinatorial therapy in enhancing therapeutic efficacy against ICI refractory murine melanoma. Methods: Unilateral and bilateral large (~330-400 mm³) poorly immunogenic B16F10 melanoma tumors were established in the flank regions of mice. Tumors were exposed to single local HT followed by an in-situ administration of αCD40 (HT+ αCD40: HT40). Inflammatory signatures post treatment were assessed using pan-cancer immune profiling and flow cytometry. The ability of HT40 ± ICI to enhance local and systemic effects was determined by immunological characterization of the harvested tissues, and by tumor growth delay of local and distant untreated tumors 4-6 weeks post treatment. Results: Immune profiling revealed that HT40 upregulated a variety of inflammatory markers in the tumors. Immunologically, HT40 treated tumors showed an increased population of granzyme B+ expressing functional CD8+ T cells (~4-fold) as well as an increased M1 to M2 macrophage ratio (~2-3-fold) and CD8+ T: regulatory T cell ratio (~5-fold) compared to the untreated control. Systemically, the proliferation rates of the melanoma-specific memory T cell population were significantly enhanced by HT40 treatment. Finally, the combination of HT40 and ICI therapy (anti-CTLA-4 and anti-PD-L1) caused superior inhibition of distant untreated tumors, and prolonged survival rates compared to the control. Conclusions: Data suggest that HT40 reprograms immunologically cold tumors and sensitizes them to ICI therapy. This approach may be clinically useful for treating advanced stage melanoma cancers.

SUBMITTER: Singh MP

PROVIDER: S-EPMC7738858 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundImmune checkpoint therapies have led to significant breakthroughs in cancer patient treatment in recent years. However, their efficiency is variable, and resistance to immunotherapies is common. VISTA is an immune-suppressive checkpoint inhibitor of T cell response belonging to the B7 family and a promising novel therapeutic target. VISTA is expressed in the immuno-suppressive tumor microenvironment, primarily by myeloid lineage cells, and its genetic knockout or antibody blockade restores an efficient antitumor immune response.MethodsFully human monoclonal antibodies directed against VISTA were produced after immunizing humanized Trianni mice and single B cell sequencing. Anti-VISTA antibodies were evaluated for specificity, cross-reactivity, monocyte and T cell activation, Fc-effector functions, and antitumor efficacy using in vitro and in vivo models to select the KVA12123 antibody lead candidate. The pharmacokinetics and safety profiles of KVA12123 were evaluated in cynomolgus monkeys.ResultsHere, we report the development of a clinical candidate anti-VISTA monoclonal antibody, KVA12123. KVA12123 showed high affinity binding to VISTA through a unique epitope distinct from other clinical-stage anti-VISTA monoclonal antibodies. This clinical candidate demonstrated high specificity against VISTA with no cross-reactivity detected against other members of the B7 family. KVA12123 blocked VISTA binding to its binding partners. KVA12123 induced T cell activation and demonstrated NK-mediated monocyte activation. KVA12123 treatment mediated strong single-agent antitumor activity in several syngeneic tumor models and showed enhanced efficacy in combination with anti-PD-1 treatment. This clinical candidate was engineered to improve its pharmacokinetic characteristics and reduce Fc-effector functions. It was well-tolerated in preclinical toxicology studies in cynomolgus monkeys, where hematology, clinical chemistry evaluations, and clinical observations revealed no indicators of toxicity. No cytokines associated with cytokine release syndrome were elevated.ConclusionThese results establish that KVA12123 is a promising drug candidate with a distinct but complementary mechanism of action of the first generation of immune checkpoint inhibitors. This antibody is currently evaluated alone and in combination with pembrolizumab in a Phase 1/2 open-label clinical trial in patients with advanced solid tumors.

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Boiling histotripsy and in-situ CD40 stimulation improve the checkpoint blockade therapy of poorly immunogenic tumors.

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