Project description:Background: Checkpoint blockade immunotherapy represented by PD-1/PD-L1 or CTLA4 antibody treatment, has been of tremendous success for multiple cancers. Most patients with prostate cancer (PCa) either do not respond to CTLA4 immune checkpoint blockade or develop resistance to it, often because of low CTLA4 antigen presentation in cancer cells.
Project description:To address RAS pathway hyperactivation and targeted therapy resistance in KRASG12C-mutant NSCLC, we evaluated the potential of the RAS(ON) G12C-selective covalent inhibitor elironrasib and the RAS(ON) multi-selective inhibitor daraxonrasib combination to maximize RAS pathway suppression and forestall pathway reactivation in a series of preclinical models. We demonstrate that the RAS(ON) inhibitor doublet induces profound and sustained tumor regressions and overcomes the increased RAS pathway oncogenic flux that underlies resistance to inactive state–selective KRASG12C inhibitors in NSCLC. Additionally, in immune-competent preclinical models, the RAS(ON) inhibitor doublet enhances tumor immune recognition by boosting antigen presentation and remodeling the suppressive tumor microenvironment, thus promoting immune-dependent complete regressions and sensitization of an immuno-refractory model to checkpoint blockade. Collectively these findings provide a preclinical rationale for the evaluation of a targeted RAS(ON) inhibitor doublet therapy regimen in combination with immune checkpoint blockade in patients with KRASG12C-mutant NSCLC.
Project description:Tumor mutational burden (TMB), usually representing high immunogenicity, could not always predict treatment response of immune checkpoint blockade (ICB). Here, we showed that defective antigen cross-presentation in type 1 conventional dendritic cells (cDC1) was responsible for lacking tumor-specific cytotoxic T lymphocytes (CTLs) in triple-negative breast cancer (TNBC) patients. Mechanistically, tumor cytosolic CDC37, shuttled via extracellular vesicles (EVs) into the endosomes of intratumor DCs, inhibited antigen cross-presentation by locking antigen binding to HSP90 and precluding their translocation from endosomes to cytoplasm. CDC37 knockdown in tumor cells or inhibiting CDC37/HSP90 interaction in DCs efficiently promoted antigen translocation and enhanced their cross-presentation, which improved ICB therapeutic responses. Clinically, high tumor CDC37 expression was associated with low infiltration of antigen-specific CTLs and poor ICB efficacy in TNBC patients. Therefore, tumor EV-shuttled CDC37 locks antigen/chaperone interaction and impairs antigen cross-presentation in DCs. Moreover, targeting CDC37 is promising to enhance anti-tumor immunity and reverse ICB resistance.
Project description:DNA mismatch repair deficient (MMR-d) cancers present an abundance of neoantigens that likely underlies their exceptional responsiveness to immune checkpoint blockade (ICB). However, MMR-d colon cancers that evade CD8+ T cells through loss of Human Leukocyte Antigen (HLA) class I-mediated antigen presentation frequently remain responsive to ICB, suggesting the involvement of other immune effector cells.
Project description:Immune evasion by cancer cells remains a major barrier to the success of immune checkpoint blockade (ICB). Here, we identify the phosphatases PTPN1 and PTPN2 as cooperative regulators of tumor immune resistance. Dual genetic ablation or pharmacologic inhibition of PTPN1/2 enhances Type I and II interferon signaling, MHC-I and CXCL9 expression, and sensitizes tumor cells to cytotoxic T lymphocyte–mediated killing. The small-molecule inhibitor KQ791 phenocopies these effects and synergizes with anti-PD1 therapy to suppress tumor growth in murine models, including immunotherapy-refractory cancers. Mechanistically, PTPN1/2 loss augments STAT1/3/5 signaling and primes cancer cells for immunogenic cell death via IFNγ/TNFα-induced pathways. Moreover, PTPN1/2 inhibition enhances antigen release and cross-presentation, promoting robust antigen-specific CD8⁺ T cell responses. These findings highlight PTPN1&2 as essential mediators of cancer immune evasion and support their inhibition as a strategy to broaden the effectiveness of immune checkpoint blockade in solid tumors.
Project description:Macrophage-directed immunotherapy has emerged as a promising strategy to eliminate tumors by unleashing phagocytosis, exemplified by blockade of the CD47-SIRPα “don’t eat me” axis. However, despite robust enhancement of phagocytosis, such approaches often fail to generate durable antitumor immunity in solid tumors, highlighting a critical disconnect between innate immune activation and effective T cell responses. Here, we identify PCSK9 as an adaptive resistance factor induced by macrophage immune checkpoint blockade. Tumor-derived PCSK9 promotes lysosomal degradation of MHC-I in macrophages, thereby impairing antigen cross-presentation and limiting CD8⁺ T cell priming. This previously unrecognized mechanism reveals how phagocytosis-targeted therapies can paradoxically suppress adaptive immunity. To overcome this resistance, we engineered bispecific fusion proteins that concurrently target the CD47-SIRPα phagocytosis checkpoint and the PCSK9–MHC-I antigen presentation axis, among which SIRPαD1-αPCSK9 emerged as the optimal format. Dual targeting synergistically enhances macrophage phagocytosis, preserves antigen cross-presentation capacity, and reprograms the tumor microenvironment toward an immunostimulatory state. Consequently, SIRPαD1-αPCSK9 elicits robust activation of both innate and adaptive antitumor immunity, leading to potent tumor control with improved safety. These findings uncover a novel mechanism of resistance to macrophage-centered immunotherapy and establish a rational dual-targeting strategy that bridges phagocytosis and T cell activation, offering a new paradigm for macrophage-driven cancer immunotherapy.
Project description:Immunosuppressive tumor-associated macrophages (TAMs) create a barrier to effective antitumor immunity and promote therapeutic resistance. Reeducating TAMs to enhance their antitumor capabilities through phenotypic remodeling remains challenging. Here, we report a modular oncolytic herpesvirus platform, engineered with a PD-L1–specific chimeric receptor integrated into the viral envelope protein (CAR-oHSV). This design endows the virus with dual tropism, enabling it to target both tumor cells and TAMs within the tumor microenvironment. In virus-resistant tumor models, CAR-oHSV preferentially targets PD-L1⁺ TAMs and triggers a STING-dependent reprogramming into a CXCL9⁺ phenotype, enhancing their tumor antigen cross-presentation capability and inducing an endogenous antitumor T cell response. Furthermore, this platform can synergize with adoptive T cell therapy and immune checkpoint blockade therapy to overcome immunotherapy resistance. Collectively, our findings define a precision-oncolytic platform that dismantles TAM-mediated immunosuppression while amplifying adaptive immunity, offering a promising translational avenue for cancer immunotherapy.
