Molecular Cancer Therapeutics最新文献

Small cell lung cancer (SCLC) is an aggressive malignancy, with most patients presenting with prognostically poor extensive-stage disease. Limited progress in standard care stresses the urgent need for novel therapies. Radiotherapy offers some survival benefit for selected patients with SCLC but could be enhanced with radiosensitizers. In this study, we identify HDAC3 as a novel radiosensitizing target in SCLC using a CRISPR knockout screen and demonstrate its efficacy and mechanism. SBC5 cells were transduced with a custom EpiDrug single-guide RNA library and treated with ionizing radiation (IR) to identify radiosensitizing genes. HDAC3 emerged as a candidate and was validated through genetic knockdown and pharmacologic inhibition (RGFP966) in multiple SCLC cell lines. Both approaches enhanced radiosensitivity, as shown by cell viability (dose modification factor10 = 1.14-1.69) and clonogenic assays (dose modification factor10 = 1.16-1.41). We assessed changes in chromatin accessibility by assay for transposase-accessible chromatin using sequencing and IR-induced DNA damage and repair using γH2AX foci detection, double-strand break (DSB) repair assays, and immunoblotting of repair proteins. HDAC3-deficient cells exhibited increased chromatin accessibility, greater IR-induced DSBs, and impaired repair capacity, resulting in persistent DNA damage. This repair defect sensitized cells to PARP inhibitors, for which combining RGFP966 with olaparib or talazoparib produced additive to synergistic effects. In SCLC xenograft models, HDAC3 knockdown or RGFP966, combined with IR, achieved significant tumor growth inhibition. Collectively, we identified HDAC3 as a novel radiosensitizing target in SCLC. Its functional loss increased the generation and persistence of IR-induced DNA DSBs, effectively sensitizing SCLC cell lines and xenografts to IR, providing a potential radiosensitization strategy to treat SCLC.

The CD47/SIRPα axis serves as a "do not eat me" signal, protecting normal cells from phagocytosis, but in the meantime, enabling immune evasion by tumor cells. Whereas substantial progress has been made in developing CD47 antagonists, achieving a balance between hematotoxicity and antitumor efficacy remains a critical challenge. In this study, we demonstrated that the bivalent anti-CD47 antibody, Hu5F9, caused severe anemia in both human CD47 knock-in mice lacking the CD47/SIRPα signal and human CD47/SIRPα double knock-in mice with complete signal, suggesting the CD47/SIRPα signal is not essential. Moreover, the single-arm CD47 antibody Hu5F9/gp120 exhibited only mild red blood cell (RBC) destruction in vitro and in vivo. These findings reveal that RBC toxicity induced by anti-CD47 antibodies is determined by the bivalency of the antibody rather than the CD47/SIRPα signal engagement. Based on this, we engineered TJH2201, a novel anti-CD47 antibody that avoids RBC agglutination while retaining high-affinity CD47 binding, robust signaling blockade, and enhanced pro-phagocytosis activity in vitro. In xenograft models with Raji and MV-4-11 cells, TJH2201 demonstrated potent antitumor activity without inducing body weight loss. These results suggest that TJH2201 is a promising CD47 antagonist that balances antitumor efficacy and hematologic safety, providing a new therapeutic approach for CD47-expressing malignancies.

NK cells can play a significant role in the antitumoral immune response. In patients with acute myeloid leukemia (AML), NK cells are, however, often found in low numbers and exhibit poor activity, contributing to leukemic progression. Allogenic NK cells are emerging as promising cellular therapies for hematologic cancer treatment. New strategies are however required to both reactivate NK cells in patients with AML and enhance the antitumor activity of transplanted NK cells. In this study, we demonstrate that targeting SUMOylation, a protein posttranslational modification, activates NK cells from both healthy donors and patients with AML. Subasumstat (TAK-981), a first-in-class inhibitor of SUMOylation used in phase I/II clinical trials, enhances NK cell degranulation, secretion of inflammatory cytokines (IFN-γ, TNF-α, and FasL), and cytotoxicity against AML cells. In vivo, TAK-981 improves the anti-leukemic efficacy of ex vivo expanded cord blood NK cells in leukemia-bearing mice. One early effect of TAK-981 is to specifically increase the accessibility and activation of cis-regulatory regions of IFN-I pathway genes and induce their transcription. TAK-981-induced secretion of IFN-β, mostly by NK cells and myeloid cells, is required for NK cell activation. Surprisingly, IFNB1 induction does not require its best-characterized activators MDA5, cGas, and IFN response factor-1, -3, and -7. Altogether, this suggests that targeting SUMOylation activates a noncanonical IFN-I pathway, which enhances the anti-leukemic potential of NK cells.

Ewing sarcoma is an aggressive bone and soft-tissue cancer affecting adolescents and young adults. In vitro and in vivo models of Ewing sarcoma have been instrumental in advancing our understanding of Ewing sarcoma biology and essential in evaluating potential therapies, particularly for metastatic or relapsed disease for which effective treatment options remain limited. Through an international collaborative effort between the Children's Oncology Group Bone Tumor Committee and the Euro Ewing Consortium, we review the current landscape of preclinical modeling used in Ewing sarcoma research encompassing both in vitro (cell lines and tumor organoids) and in vivo (mouse and nonmammalian xenografts) model systems. We discuss factors that can influence experimental results, provide testing considerations for both in vitro and in vivo studies, and descriptions of existing preclinical data repositories. We highlight current needs in Ewing sarcoma modeling and the importance of enhanced international cooperative research and patient advocacy efforts which will be critical in expanding our resources of biologically relevant Ewing sarcoma models to enable translation of preclinical findings into effective therapeutic strategies for patients with Ewing sarcoma.

Trastuzumab deruxtecan (T-DXd) is an ERBB2/HER2-targeting antibody-drug conjugate (ADC) with efficacy across adult cancers exhibiting variable HER2 expression. Prior studies demonstrating HER2 expression in osteosarcoma motivated a clinical trial of T-DXd in pediatric and adolescent/young adults with osteosarcoma, but the trial was terminated early because of inactivity. We evaluated the activity of T-DXd using osteosarcoma patient-derived xenograft (PDX) models and found a 22% objective response rate despite no detectable HER2 expression across PDXs tested. To further assess non-HER2-mediated activity, we evaluated the activity of T-DXd across 31 pediatric cancer cell lines and found osteosarcoma to be amongst the most resistant to T-DXd, as well as unconjugated deruxtecan, providing a potential explanation for the negative results observed in the clinical trial of T-DXd in osteosarcoma. T-DXd evaluation in PDX models representing pediatric histologies with greater intrinsic sensitivity to deruxtecan, including pediatric renal tumors and desmoplastic small round cell tumor, revealed both HER2-enhanced activity as well as substantial non-HER2-mediated activity, as evidenced by equipotent activity using an isotype-matched control ADC. Together, these results underscore translational opportunities for ADC therapeutics in tumor histologies with high sensitivity to the payload and in which enhanced tumor delivery may be mediated by antibody-targeted mechanisms as well as macromolecular characteristics of ADCs (e.g., enhanced permeability and retention effect) and tumor microenvironmental factors (e.g., proteolytic payload release). Our findings challenge the role of HER2 as a biomarker predictive of T-DXd response in pediatric cancers and support further biomarker-agnostic clinical development of T-DXd in desmoplastic small round cell tumor and pediatric renal tumors.

The genetic instability of cancer cells leads to cellular resistance against most targeted cancer drugs. Cancer-associated fibroblasts (CAF) infiltrate all carcinomas and are genetically stable. Using antibody-drug conjugates (ADC), we exploit the unique properties of a rapidly recycling endocytic receptor, uPARAP, to achieve highly efficient CAF-mediated drug delivery and killing of carcinomas. This receptor is generally not present on carcinoma cells and is only expressed in a restricted group of mesenchymal cancer cell types, which are sensitive to uPARAP-directed ADCs. However, we show that uPARAP is highly expressed in CAFs in all carcinoma types examined. This property is recapitulated in mouse xenograft carcinoma models. In these models, despite the absence of uPARAP on the carcinoma cells, uPARAP-targeting ADCs with clinically validated payloads, monomethyl auristatin E and deruxtecan, eradicated tumors with remarkable efficiency. Systemic treatment with anti-uPARAP ADC led to the permanent eradication of tumors in mice carrying subcutaneous xenografts with human EBC-1 lung carcinoma cells. A pronounced repression of tumor growth and a strongly increased mouse survival rate were also obtained with human HT29 colon adenocarcinoma cells, both when these tumors were growing subcutaneously and after the homing of tumor cells to bone from the circulation. CAFs were largely refractory to ADC treatment and retained a high expression of uPARAP. uPARAP-expressing fibroblasts could also process an anti-uPARAP ADC in vitro and deliver the cytotoxic component to carcinoma cells. The current bystander mechanism may be exploited in the majority of the most prevalent solid cancers, thus making uPARAP an extraordinarily versatile target for ADC-based cancer treatment.

In this work, we show that the combination of radiotherapy (RT) and an IL15/IL15Rα fusion complex (IL15c) fails to confer antitumor efficacy; however, a CD8-driven antitumor immune response can be elicited with the concurrent administration of an aCD25 regulatory T cell-depleting antibody. Using IL15-/- and Rag1-/- knockout mouse models, we show that the response to RT + IL15c + aCD25 is dependent on both IL15 and cytotoxic T lymphocytes. Furthermore, despite an equivalent survival benefit following treatment with RT + IL15c + aCD25 and combination RT and PD1-IL2v, a novel immunocytokine with PD1- and IL2Rβγ-binding domains, cytotoxic T lymphocyte immunophenotyping and phosphoproteomics analysis of intracellular metabolites showed a significant upregulation of activation and functionality in CD8 T cells in the RT + PD1-IL2v regimen. Finally, we show that in the absence of functional IL15 signaling, the immunostimulatory response to RT + PD1-IL2v is significantly diminished with a concurrent lack of TCF+ CD8 T-cell generation, suggesting a necessity of IL15 for CD8 stem cells in mediating a durable response to treatment. Together, our results are illustrative of a mechanism wherein unimpeded effector T-cell activation through IL2Rβ signaling and regulatory T-cell inhibition are necessary in mediating an antitumor immune response.

General control nonderepressible 2 (GCN2; EIF2AK4) is a serine-threonine kinase in the integrated stress response signaling pathway that initiates adaptive responses during nutrient stress conditions. Although pharmacologic inhibition of GCN2 under nutrient stress conditions induces apoptosis and inhibits tumor growth, GCN2 inhibition without nutrient stress has been reported to have no effect on tumor growth. By exploring an array of GCN2 inhibitors, we demonstrate that multiple agents in fact activate GCN2 in biochemical and cell-based assays at low concentrations and inhibit GCN2 at higher concentrations. Unexpectedly, it is this activation, and not inhibition, of the GCN2 pathway that is associated with decreased viability in vitro and tumor growth inhibition in vivo across multiple models. Knockdown and knockout experiments show that activation of the integrated stress response by GCN2-targeting agents is dependent on GCN2. ISRIB, a modulator of eIF2B, ablates the viability effect, demonstrating the dependence on translation initiation. Activating doses result in the induction of cleaved caspase 3 and cleaved PARP. In contrast, a nonactivating GCN2-targeting agent does not affect viability. These results provide a clearer understanding of the challenges and opportunities for the clinical development of compounds targeting GCN2.

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal form of pancreatic cancer, with poor prognosis driven by late diagnosis, therapeutic resistance, and an immunosuppressive tumor microenvironment. Interactions between tumor cells and immune cells promote immune evasion and tumor progression, limiting the efficacy of immune checkpoint blockade and other immunotherapies. Given the high expression of TROP2 in PDAC, we developed a TROP2-targeted TLR7 agonist (E104) designed for selective accumulation within the tumor microenvironment to activate antitumor immunity. Although antibody bioactivity is traditionally linked to Fcγ receptor (FcγR) engagement and recruitment of effector cells, our legumain-cleavable, non-glycosylated immune-stimulating antibody conjugates (NG-ISACs) induce robust myeloid activation, cytokine release, and tumor regression without FcγR-mediated functions of natural killer cells or macrophages. Rather, NG-anti-TROP2-E104-ISACs depend on tumor antigen recognition and TLR7 activation, not FcγR-driven antibody-dependent cellular cytotoxicity (ADCC) or antibody-dependent cellular phagocytosis (ADCP), to elicit tumor regression and adaptive immunity, as evidenced by anti-TROP2 antibody generation in a syngeneic model. By incorporating the cell-permeable E104 payload with bystander activity, NG-ISACs can activate immune responses independently of FcγR binding. In vitro, NG-anti-TROP2-E104-ISACs bypass FcγRIIa-mediated ADCC and FcγRIIIa-mediated ADCP while maintaining potency in co-cultures of TROP2-positive tumor and effector cells. Moreover, NG-anti-TROP2-E104-ISACs display reduced acute toxicity compared to glycosylated counterparts. Together, these findings delineate the bystander mechanism underlying FcγR-independent immune stimulation and establish a framework for designing ISACs with improved safety.

This study evaluates PM534, a novel colchicine-binding domain inhibitor, for its potential in cancer therapy. PM534 exhibited potent in vitro efficacy against a panel of fourteen human cancer cell lines, including breast, ovarian, and prostate cancers, with GI50 values in the low nanomolar range. Both continuous (72 hours) and short-term (1-24 hours) exposure led to irreversible effects, inducing G2/M cell cycle arrest and multinucleation. Additionally, PM534 also impaired angiogenic process. It effectively inhibited HUVEC cell functions, including adhesion with an IC50 of 2.3 nM, markedly more potent than colchicine (IC50 = 1,800 nM). At concentrations as low as 1.6 nM, PM534 delayed wound closure in migration assays, completely inhibiting migration above 4 nM. Additionally, PM534 abrogated invasion and disrupted capillary-like network formation at concentrations starting from 0.5 nM, without inducing cytotoxicity. In vivo PM534 demonstrated robust antitumor efficacy across six xenograft models, including ovarian (A2780, ES-2), triple-negative breast (MDA-MB-231, HCC-1937), and prostate (VCaP, 22Rv1) tumors. This treatment also led to statistically significant increases in median survival times across all models, without inducing signs of systemic toxicity. Mechanistically, PM534 induced apoptosis, mitotic catastrophe, and necrosis in tumor tissues. Importantly, PM534 retained efficacy in models overexpressing multidrug resistance proteins P-glycoprotein or β-III tubulin, overcoming common resistance mechanisms that limit the effectiveness of other tubulin-binding agents. Collectively, these findings highlight PM534 as a promising antitumor agent with potent activity against diverse and treatment-resistant malignancies. A Phase I clinical trial (NCT05835609) is underway to assess the therapeutic potential of PM534 in patients with advanced solid tumors.