Molecular Cancer Therapeutics最新文献

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer. Among TNBC subtypes, the luminal androgen receptor (LAR) subtype expresses high levels of androgen receptor (AR) and generally responds poorly to neoadjuvant chemotherapy. AR has been reported as a promising therapeutic target for the LAR TNBC subtype. Here, we evaluated the preclinical antitumor efficacy of enzalutamide, an AR inhibitor, in TNBC. Enzalutamide had moderate anti-proliferation activity against AR-positive (AR+) TNBC cells (IC50 > 15 µM). To enhance its antitumor efficacy, we performed high-throughput kinome siRNA screening and identified the cell cycle pathway as a potential target. Inhibition of cell cycle progression using the CDK7 inhibitor KRLS-017 showed a synergistic anti-proliferation effect with enzalutamide in AR+ LAR MDA-MB-453 and SUM185 TNBC cells. Downstream target analysis revealed that enzalutamide and KRLS-017 combination dramatically reduced c-MYC expression at both mRNA and protein levels. c-MYC knockdown significantly suppressed growth of MDA-MB-453 and SUM185 cells to a degree comparable to that of enzalutamide and KRLS-017 combination treatment, whereas c-MYC overexpression reversed the synergistic effect. An enhancement in inhibition of tumor growth and suppression of c-MYC expression was further confirmed when enzalutamide combined with KRLS-017 in an MDA-MB-453 mouse model. Our study suggests that KRLS-017 enhances the antitumor efficacy of enzalutamide by inhibiting c-MYC-mediated tumorigenesis and presents a potential new approach for treating AR+ LAR TNBC.

Adoptive cell therapy (ACT) using retrovirally transduced T cells represents a promising strategy for enhancing antitumor responses. When used with TriVax, a peptide vaccination strategy, this approach synergistically expands antigen-specific cell populations. STAT5 plays a vital role as a transcription factor in regulating T cell proliferation and their differentiation into effector and memory T cells. We aimed to explore the combination therapy using CD8 T cells engineered to express constitutively active STAT5 (CA-STAT5) with vaccines. CD8 T cells were transduced with a retrovirus (RV) encoding the mouse gp100 T cell receptor (TCR). In certain treatment groups, cells were also co-transduced with RV encoding CA-STAT5. We assessed transduction efficiency and functional activity through flow cytometry and various functional assays. B16F10 tumor-bearing mice were treated with ACT using RV-transduced CD8 T cells and subsequently vaccinated with TriVax. We demonstrate that TriVax selectively enhanced the expansion of ACT cell populations bearing gp100-specific TCRs. T cells engineered to express CA-STAT5 showed not only increased expansion and polyfunctionality but also reduced PD-1 expression, leading to decreased cellular exhaustion. In a B16F10 melanoma mouse model, our approach yielded a potent antitumor effect, with CA-STAT5 further amplifying this response. We found that CA-STAT5 improved antitumor activities, in part, by attenuating the PD-1/PD-L1 inhibitory pathway. These findings indicate that TCR-transduced CD8 T cells can undergo antigen-dependent expansion when exposed to TriVax. Additionally, the expression of CA-STAT5 enhances T cell proliferation and persistence, partly by promoting resistance to PD-1/PD-L1-mediated inhibition in antitumor T cells.

Bispecific antibodies (BsAbs) combining simultaneous PD-L1 blockade and conditional co-stimulatory receptor activation have been developed to improve immune checkpoint therapy response. However, several PD-L1-based BsAbs have encountered clinical challenges, including insufficient activity or unexpected toxicity. In this study, we propose OX40 as a more suitable target partner for PD-L1-based BsAb design compared to ongoing clinical partners (CD27 and 4-1BB). We present a novel Fc-silenced tetravalent PD-L1/OX40 BsAb (EMB-09), which efficiently blocks PD-1/PD-L1 interactions and induces PD-L1-dependent OX40 activation, leading to enhanced T cell activation. EMB-09 demonstrated improved anti-tumor activity compared to the anti-PD-L1 monoclonal antibody. Significantly, EMB-09 activated effector memory T cells in peripheral immune system, promoted the influx of stem-like CD8+ T cells into the tumor site, resulting in a more active phenotype of CD8+ tumor-infiltrating lymphocytes. In an ongoing first-in-human study in patients with advanced refractory solid tumors (NCT05263180), EMB-09 demonstrated a consistent pharmacodynamic response and early efficacy signals.

Autotaxin (ATX), encoded by ENPP2, is a clinical target in pancreatic ductal adenocarcinoma (PDAC). ATX catalyzes the production of lysophosphatidic acid (LPA), an important regulator within the tumor microenvironment (TME), yet the pro-tumorigenic action of the ATX/LPA axis in PDAC remains unclear. Here, by interrogating patient samples and cell line datasets, we show that the PDAC TME, rather than cancer cells, is responsible for the majority of ENPP2 expression, and highlight a key role for cancer associated fibroblast (CAF)-derived ATX in autocrine and paracrine pro-tumorigenic signaling. Using the clinical-stage ATX inhibitor, IOA-289, we identified connective tissue growth factor (CTGF) as a downstream mediator of ATX signaling in the PDAC CAF-derived cell line, 0082T. Genetic ablation or pharmacological inhibition of ATX in 0082T CAFs reduced CTGF secretion via modulation of LPA/LPA receptor (LPAR) signaling. Despite the loss of ATX function, extracellular levels of LPA were paradoxically increased, indicating a role for ATX beyond its enzymatic activity and suggesting a role for its LPA chaperone function in the LPA/LPAR signaling in CAFs. As CAFs are the main source for CTGF in the PDAC TME, these findings suggest a role for ATX in promoting pro-tumorigenic microenvironment via modulation of CAF secretion, not only via its LPA-producing activity but also via its LPA chaperone function, providing a potential mechanism for the anti-tumor effects of ATX inhibition.

Trophoblast cell surface antigen 2 (TROP2) exhibits aberrant expression in pancreatic cancer, correlating with metastasis, advanced tumor stage and poor prognosis of pancreatic ductal adenocarcinoma (PDAC) patients. TROP2 has been recognized as a promising therapeutic target for antibody drug conjugates (ADCs), as evidenced by the approval of the anti-TROP2 ADC Trodelvy® for the treatment of triple negative breast cancer. In this study we report the generation of novel second-generation amanitin based ADCs (ATAC®s) targeting TROP2, comprising the humanized RS7 antibody of Trodelvy® (hRS7) and the highly potent payload amanitin. The specific in vitro binding, efficient antigen internalization, and high cytotoxicity of hRS7 ATAC®s with half maximal effective concentration (EC50) values in the picomolar range in TROP2-expressing cells constituted the foundation for preclinical in vivo evaluation. The hRS7 ATAC®s demonstrated a significant reduction in tumor growth in vivo in subcutaneous xenograft mouse models of pancreatic cancer and triple negative breast cancer at well-tolerated doses. The antitumor efficacy correlated with the level of TROP2 expression on the tumors and the in vivo tumor uptake of the ATAC®s. The long half-life of 9.7-10.7 days of hRS7 ATAC®s without premature payload release in serum supported a high therapeutic index. Notably, the efficacy of the hRS7 ATAC®s was superior to that of Trodelvy® with complete tumor eradication in both, refractory pancreatic and triple negative breast cancer xenograft models. In summary, hRS7 ATAC®s represent a highly effective and well-tolerated targeted therapy, and our data support their development for pancreatic cancer and other TROP2-expressing tumors.

The treatment of non-small cell lung cancer has made major strides with the use of immune checkpoint inhibitors, but there remains a significant need for therapies that can overcome immunotherapy resistance. Dendritic cell (DC) vaccines have been proposed as a therapy that can potentially enhance the antitumor immune response. We have embarked on a phase I clinical trial of a vaccine consisting of monocyte-derived DCs (moDCs) modified to express the chemokine CCL21 (CCL21-DC) given in combination with pembrolizumab. Here, we report a comprehensive characterization of this CCL21-DC vaccine and interrogate the effects of multiple factors in the manufacturing process. We show that the cellular makeup of the CCL21-DC vaccine is heterogeneous due to the presence of passenger lymphocytes at a proportion that is highly variable among patients. Single cell RNA sequencing of vaccines revealed further heterogeneity within the moDC compartment, with cells spanning a spectrum of DC phenotypes. Transduction with a CCL21-containing adenoviral vector augmented CCL21 secretion by moDCs but otherwise had a minimal effect on vaccine characteristics. A single freeze-thaw cycle for stored vaccines was associated with minor alterations to the DC phenotype, as was the use of healthy donors rather than patient autologous blood. Our results highlight important considerations for the production of DC vaccines and identify underexplored factors that may affect their efficacy and immunologic impact.

ATM inhibitors are being developed as radiosensitizers to improve the antitumor effects of radiotherapy, but ATM inhibition can also radiosensitize normal tissues. Therefore, understanding the elevated risk for normal tissue toxicities is critical for radiosensitizer development. This study focused on modeling the relationship between acute mucosal toxicity, radiation dose, fractionation schedule, and radiosensitizer exposure. The ATM inhibitor WSD0628 was combined with single or fractionated doses of radiation delivered to the oral cavity or esophagus of FVB mice. The potentiation by WSD0628 was quantified by a sensitizer enhancement ratio (SER), which describes the changes in radiation tolerance for radiation combined with WSD0628 relative to radiation-only regimens. WSD0628 profoundly enhanced radiation-induced acute oral and esophageal toxicities. For oral mucosal toxicity, the enhancement by WSD0628 with 3 fractions of radiation resulted in an SER ranging from 1.3 (0.25 mg/kg) to 3.1 (7.5 mg/kg). For the 7.5 mg/kg combination, the SER increased with increasing number of fractions from 2.2 (1 fraction) to 4.3 (7 fractions) for oral toxicity and from 2.2 (1 fraction) to 3.6 (3 fractions) for esophageal toxicity, which reflects a loss of the normal tissue sparing benefit of fractionated radiation. These findings were used to develop a modified biologically effective dose model to determine alternative radiation schedules with or without WSD0628 that result in similar levels of toxicity. Successful radiosensitizer dose-escalation to maximally effective therapeutic dose will require careful deliberation of tumor site and reduction of radiation dose-volume limits for organs at risk.

Major risk factors of head and neck squamous cell carcinoma (HNSCC) are tobacco use and human papillomavirus (HPV). HPV E6 oncoprotein leads to p53 degradation, whereas HPV-negative cancers are frequently associated with TP53 mutations. Peposertib is a potent and selective, orally administered small-molecule inhibitor of the catalytic subunit of the DNA-dependent kinase (DNA-PKcs), a key regulator of non-homologous end joining (NHEJ). NHEJ inhibition along with irradiation (IR)-induced DNA double-strand breaks has the potential to increase antitumor treatment efficacy. Here, we investigated the responses of a panel of HNSCC models with distinct HPV and p53 status to treatments with IR, DNA-PKcs inhibition, and their combination in-vitro and in-vivo. IR-induced DNA damage combined with peposertib administration shortly before IR results in decreased cell viability and proliferation and causes DNA repair delay in all studied HNSCC cell lines. However, our data confirm that the actual cell fate upon this treatment is determined by cellular p53 and/or HPV status. Cells lacking functional p53 due to its degradation by HPV or due to a loss-of-function mutation are arrested in the G2/M phase of the cell cycle and eliminated by apoptosis whereas p53-proficient HNSCC cell lines preferentially undergo senescence. This is also recapitulated in-vivo, where HPV+ UD-SCC-2 xenografts display stronger and more durable responses to the combined treatment as compared to p53 wild-type UM-SCC-74A tumors. In conclusion, DNA-PKcs inhibitor peposertib should be further studied as a potential radiosensitizer for HNSCCs, taking into consideration the genetic background and the HPV status of a particular tumor.

Antibody-drug conjugates (ADC) have shown impressive clinical activity with approval of many agents in hematologic and solid tumors. However, challenges remain with both efficacy and safety of ADCs. This study describes novel trastuzumab-auristatin conjugates with the hydrophilic monomethylauristatin E (MMAE) prodrug MMAU, and optimization of a glycopeptide linker leading to a wider therapeutic window. Trastuzumab was conjugated with auristatin payloads via a series of linkers using a stabilized maleimide handle. The ADCs were characterized in vitro and their relative in vivo antitumor efficacies were assessed in HER2+ xenograft models. Relative linker stabilities and the mechanism of linker cleavage were studied using in vitro assays. Toxicity and toxicokinetics of the best performing ADC were evaluated in cynomolgus monkey (cyno). The trastuzumab-MMAU ADC with stabilized glycopeptide linker showed maleimide stabilization and higher resistance to cleavage by serum and lysosomal enzymes compared with a valine-citrulline conjugated trastuzumab ADC (trastuzumab-vc-MMAE). A single dose of 1 or 2 mg/kg of trastuzumab-MMAU at drug-to-antibody ratios (DAR) of eight and four respectively resulted in xenograft tumor growth inhibition, with superior efficacy to trastuzumab-vc-MMAE. Trastuzumab-MMAUDAR4 was tolerated at doses up to 12 mg/kg in cyno, which represents 2- to 4-fold higher dose than that observed with vedotin ADCs, and had increased terminal half-life and exposure. The optimized trastuzumab-MMAU ADC showed potent antitumor activity and was well tolerated with excellent pharmacokinetics in nonhuman primates, leading to a superior preclinical therapeutic window. The data support potential utility of trastuzumab-MMAU for treatment of HER2+ tumors.

Sarcomas are a heterogeneous group of rare cancers that originate in soft tissues or bones. Their complexity and tendency for metastases make treatment challenging, highlighting the need for new therapeutic approaches to improve patient survival. The difficulties in treating these cancers primarily stem from abnormalities within the tumor microenvironment (TME), which leads to reduced blood flow and oxygen levels in tumors. Consequently, this hampers the effective delivery of drugs to tumors and diminishes treatment efficacy despite higher toxic doses of chemotherapy. In this study, we tested the mechanotherapeutic ketotifen combined with either pegylated liposomal doxorubicin (PLD) or pegylated liposomal coencapsulated alendronate-doxorubicin (PLAD) plus anti-programmed cell death protein 1 antibody in mouse models of fibrosarcoma and osteosarcoma. We found that ketotifen successfully reprogrammed the TME by reducing tumor stiffness and increasing perfusion, proven by changes measured by shear-wave elastography and contrast-enhanced ultrasound, respectively, and enhanced the therapeutic efficacy of our nanomedicine-based chemo-immunotherapy protocols. Furthermore, we observed a trend toward improved antitumor responses when nano-chemotherapy is given alongside anti-programmed cell death protein 1 and when the immunomodulator alendronate was present in the treatment. We next investigated the mechanisms of action of this combination. Ketotifen combined with nanomedicine-based chemo-immunotherapy increased T-cell infiltration, specifically cytotoxic CD8+ T cells and CD4+ T helper cells, and decreased the number of regulatory T cells. In addition, the combination also altered the polarization of tumor-associated macrophages, favoring the M1 immune-supportive phenotype over the M2 immunosuppressive phenotype. Collectively, our findings provide evidence that ketotifen-induced TME reprogramming can improve the efficacy of nanomedicine-based chemo-immunotherapy in sarcomas.