Molecular Cancer Therapeutics最新文献

The Werner syndrome helicase (WRN) is a promising target for cancers with microsatellite instability (MSI) leading to the initiation of at least five Phase I clinical trials. Acquired resistance is a substantial obstacle for obtaining lasting benefit from targeted therapies in oncology and may be particularly acute in the setting of mismatch repair deficient (dMMR) tumors, which can sample increased fitness landscapes owing to higher mutational burden. In this study, we characterized resistance mechanisms using the clinical candidate HRO761 and two novel inhibitors in MSI cell lines and xenograft models. We observed rapid emergence of resistance both in vitro and in vivo, with sequencing revealing clustered mutations within the WRN helicase domain. Computational structural analyses indicated these mutations either directly interfere with inhibitor binding or alter the protein conformation required for inhibitor engagement. Notably, while most mutations conferred broad resistance across all three compounds, we identified specific alterations (L528S, C727R, and F730L) that exhibited selectivity between chemical scaffolds. This chemotype-specific resistance profile suggests opportunities for developing next-generation inhibitors that retain activity against resistant variants and for implementing rational treatment strategies with existing inhibitors. Overall, our findings demonstrate that on-target resistance to WRN inhibitors emerges rapidly in dMMR backgrounds but also highlight potential approaches to overcome resistance, supporting continued development of WRN-targeted therapies for MSI cancers.

Neuroendocrine prostate cancer (NEPC) is an aggressive variant of prostate cancer with limited therapeutic options. Delta-like ligand 3 (DLL3) is a cell-surface protein and therapeutic target expressed in the vast majority of NEPC tumors. The DLL3-targeted T cell-activating construct MK-6070 (formerly called HPN328) binds to both DLL3 on tumor cells and CD3 on T cells, as well as serum albumin to extend half-life. A phase I/II trial of MK-6070 is currently underway, which includes an NEPC cohort (NCT04471727). In this study, we report the preclinical activity of MK-6070 in prostate cancer models, showing high specificity and antitumor activity in DLL3-expressing NEPC models both in vitro and in vivo, with T-cell activation and tumor infiltration of T cells after treatment. MK-6070 also demonstrates antitumor activity in mixed tumors, affecting DLL3-negative prostate cancer cells after engagement with surrounding DLL3-expressing tumor cells, supporting a potential bystander effect. Overall, these data demonstrate the promising activity of MK-6070 in NEPC preclinical models including heterogeneous tumors, supporting the clinical development of MK-6070.

KRAS G12D is a common oncogenic driver mutation in diverse cancers, including non-small cell lung cancer, colorectal cancer, and pancreatic cancer. KRASG12D inhibitors have recently progressed into clinical trials but will likely face innate or acquired drug resistance similar to that which has been observed for KRASG12C inhibitors, such as activation of receptor tyrosine kinases, KRAS independence, and reactivation of RAS-MAPK signaling. This study investigates heterobifunctional small-molecule dual inhibitors that simultaneously target both KRASG12D and protein chaperone HSP90 in KRASG12D-mutated cancer cell lines and patient-derived organoids. Our findings reveal that the efficacy of the clinical-stage KRASG12D inhibitor MRTX1133 varies, with notable resistance being observed in some cell line and organoid models. In contrast, KRASG12D-HSP90 dual inhibitors were found to broadly display superior effectiveness in inducing apoptosis, reducing cell viability, and suppressing key downstream signaling pathways such as AKT and ERK1/2 in MRTX1133-resistant models. The rationale for targeting HSP90, which is preferentially activated in cancer cells, alongside KRASG12D, arises from the ability of HSP90 inhibition to destabilize substrate client proteins that are essential for cancer cell survival and have also been implicated in resistance to KRAS inhibitors. This dual-inhibitor approach presents a promising new strategy to combat de novo and acquired drug resistance in KRASG12D-mutated cancers and potentially paves the way for improved clinical outcomes by addressing the complex molecular mechanisms underlying cancer cell evolution that enables resistance to conventional inhibitors.

The tumor landscape of pancreatic ductal adenocarcinoma (PDAC) is refractory to conventional photon radiotherapy (RT) because of a fibrotic tumor microenvironment (TME) that promotes chronic hypoxia and reduced immune surveillance. The radiobiological factors unique to carbon ion RT (CIRT), such as high linear energy transfer and less dependence on oxygen, make it well-suited to overcome the PDAC TME. In this study, we utilized clonal syngeneic KPC pancreatic tumor cell lines and tumors to examine this postulate and to identify underlying factors that affect the response of PDAC to CIRT. Although KPC cell lines exhibited radiobiological effectiveness greater than 3, subcutaneous tumors in the mouse hind leg showed lower radiobiological effectiveness-1.3 based on quintupling time-at a linear energy transfer between 70 and 80 keV/μm. Four days after CIRT, we observed widespread transcriptomic changes in the tumor immune microenvironment, suggesting increased infiltration of antitumor immune cells and elevated expression of antitumor T-cell cytokines, MHC class I molecules, and co-stimulatory signals. Fewer immunologic changes were observed following photon irradiation. By 7 days after CIRT, tumor-supportive transcriptomic programs characterized by protumor cytokines, M2 macrophages, and cancer-associated fibroblasts emerged, promoting resistance and limiting the durability of tumor growth delay. These findings suggest that CIRT may offer a favorable platform compared with conventional photon RT for combining with immunotherapies. Furthermore, these data highlight the risk of using in vitro survival data alone in treatment planning and indicate that underlying TME factors affect the response of PDAC in vivo.

LIV-1 is a transmembrane protein belonging to the zinc transporter family and represents a promising target for antibody-drug conjugate (ADC) therapy because of its broad expression in tumors and limited normal tissue expression. Ladiratuzumab vedotin (SGN-LIV1A), a LIV-1-targeting ADC with a payload of monomethyl auristatin E, has been discontinued from clinical development. The preliminary clinical results demonstrated promising efficacy in triple-negative breast cancer but no response in hormone receptor-positive/HER2-negative breast cancer, along with typical monomethyl auristatin E-related adverse events. In this study, we demonstrated a novel LIV-1-directed ADC, SDP-LIV1, consisting of an in-house developed anti-LIV-1 antibody conjugated to a proprietary topoisomerase I inhibitor via a cleavable glycine-glycine-phenylalanine-glycine linker, with an optimized average drug-to-antibody ratio of 6. Preclinical studies revealed that SDP-LIV1 showed promising in vitro and in vivo efficacy in breast and gastric cancers with favorable preclinical pharmacokinetics and safety profiles, suggesting that SDP-LIV1 has great potential for the clinical treatment of patients with solid tumors expressing LIV-1.

Neurofibromatosis type I (NF1) is a common cancer predisposition syndrome caused by heterozygous loss-of-function mutations in the tumor-suppressor gene NF1. Individuals with NF1 develop benign tumors of the peripheral nervous system (neurofibromas), originating from the Schwann cell (SC) lineage after somatic loss of the wild-type NF1 allele, some of which progress further to malignant peripheral nerve sheath tumors (MPNST). There is only one FDA-approved targeted therapy for symptomatic plexiform neurofibromas and none approved for MPNSTs. The genetic basis of NF1 syndrome makes associated tumors ideal for using synthetic drug sensitivity approaches to uncover therapeutic vulnerabilities. We developed a drug discovery pipeline to identify therapeutics for NF1-related tumors using isogeneic pairs of NF1-proficient and NF1-deficient immortalized human SCs. We utilized these in a large-scale high-throughput screen for drugs that preferentially kill NF1-deficient cells, through which we identified 23 compounds capable of killing NF1-deficient SCs with selectivity. Multiple hits from this screen clustered into classes defined by the method of action. Four clinically interesting drugs from these classes were tested in vivo using both a genetically engineered mouse model of high-grade PNSTs and human MPNST xenografts. All drugs tested showed single-agent efficacy in these models as well as significant synergy when used in combination with the MEK inhibitor selumetinib. This high-throughput screen platform yielded novel therapeutically relevant compounds for the treatment of NF1-associated tumors and can serve as a tool to rapidly evaluate new compounds and combinations in the future.

Dysregulated ribosome biogenesis and p53 mutations are known to play oncogenic roles in various cancers, including pancreatic cancer. In this study, we demonstrated the therapeutic potential of BMH-21, a pharmacologic inhibitor of RNA polymerase I, against pancreatic cancer by uncovering a novel molecular mechanism involving RPA194-mediated ubiquitination of mutant p53 without affecting the ubiquitination of wild-type p53. Our key findings are that (i) BMH-21 selectively induces apoptosis and cell growth inhibition of pancreatic cancer cells with no effect on normal human pancreatic ductal epithelial cells; (ii) BMH-21 degrades RPA194; (iii) BMH-21 inhibits recruitment of both RPA194 and RPA135 on rDNA to suppress pre-rRNA synthesis; (iv) RPA194 physically interacts with p53 and BMH-21-induced degradation of RPA194 selectively exposes truncated and mutated p53 for ubiquitination with no effect on ubiquitination of wild-type p53 in pancreatic cancer cells; and (v) BMH-21 treatment significantly reduces the growth of orthotopic xenograft pancreatic tumors in athymic nude mice with no observed toxicity. Altogether, these findings suggest that BMH-21 is a promising, nontoxic therapeutic agent for patients with pancreatic cancer with aberrant ribosome biogenesis and mutant p53, offering a potential new avenue for targeted treatment.

Gene-directed enzyme prodrug therapy represents a promising antitumor strategy owing to its low systemic toxicity. However, clinical translation has been hindered by challenges in suicide gene delivery. Artificially engineered circular RNA (circRNA) demonstrates exceptional potential for gene delivery when combined with lipid nanoparticle technology, exhibiting high stability, prolonged protein-coding capacity, and cost-effective production. We developed an in vitro synthesized circRNA encoding the cytosine deaminase-uracil phosphoribosyltransferase (circCDUPRT). Upon intratumoral administration, circCDUPRT achieved sustained intratumoral expression with minimal systemic toxicity. The combination of circCDUPRT and prodrug 5-fluorocytosine showed significant antitumor efficacy in both in vitro and in vivo tumor models. In advanced melanoma models, combining circCDUPRT/5-fluorocytosine with IL-15-expressing circRNA potently enhanced the expansion and activation of CD8+ T and NK cells. Collectively, these findings establish the synthetic circRNA platform as a cost-effective, high-efficiency delivery system for gene-directed enzyme prodrug therapy and immunotherapy applications.

Drug repurposing is the process of reusing existing pharmaceuticals for novel clinical purposes, which offers advantages such as streamlined clinical trial access and reduced drug development costs. Clarithromycin (CAM), a member of the macrolide antibiotics family, is a promising candidate for repurposing in cancer therapy due to its known preclinical and clinical immunomodulatory and anticancer properties. In the current study, we investigated whether CAM could be repurposed as a preventive treatment for KRAS-mutant lung cancer, a subtype of lung adenocarcinoma that is strongly associated with heavy smoking. CCSPCre; LSL-KrasG12D mice at an early stage of tumor development were treated with different doses of CAM for 10 weeks. While exhibiting an excellent safety profile, CAM was able to prevent the development of premalignant and malignant lung lesions in a dose-dependent manner. In addition, CAM significantly reduced the infiltration of neutrophils/polymorphonuclear myeloid-derived suppressor cells and inhibited the mRNA expression of protumor inflammatory cytokines IL-6, TNFα, and IL-1β, as well as M2 macrophage markers Fizz1 and Arginase1 in the lung tumor microenvironment. Moreover, we investigated the effect of CAM in reshaping the intestinal and lung microbiome. Long-term CAM usage decreased intestinal microbiome diversity but, more notably, significantly increased the abundance of the probiotic genus Muribaculaceae while decreasing the abundance of Desulfovibrio, a genus associated with the promotion of various malignancies. Taken together, we conclude that CAM could provide promising cancer prevention efficacy in KRAS-mutant lung cancer due to its immunomodulatory properties on the tumor microenvironment and its regulatory effects on the microbiome.

Bispecific antibodies (BsAb) are a rapidly advancing class of biopharmaceuticals with substantial potential for cancer immunotherapy. Although BsAbs have shown notable success in treating certain hematologic malignancies, their application for solid tumors remains limited. The extra domain B (EDB) of fibronectin represents a promising pan-tumoral stromal target, offering an attractive alternative to conventional cellular tumor antigens, which often face limitations with respect to specificity in solid tumors. In this study, we describe the generation and characterization of a T cell-engaging BsAb that targets murine CD3 using the 2C11 clone and EDB with the L19 clone. Specifically, the BsAb consists of a Fab fragment (targeting CD3) fused with two single-chain Fv fragments (targeting EDB) at the C-terminus. The BsAb was produced in Chinese hamster ovary cells and purified to homogeneity. To compare stromal and cellular targeting, two murine tumor cell lines naturally secreting EDB in the stroma were transduced to express the target on the cell surface. In both cell lines, biodistribution analysis revealed increased tumor uptake in the cellular model compared with the stromal one. Similarly, treating immunocompetent cellular EDB tumor-bearing mice with the BsAb improved anticancer activity. By contrast, no significant therapeutic benefit was observed in the stromal model. These findings underscore the importance of direct tumor cell targeting compared with stromal targeting for effective BsAb therapy.