Molecular Cancer Therapeutics最新文献

We have previously demonstrated that Claudin-2 is required for colorectal cancer (CRC) liver metastasis. The expression of Claudin-2 in primary CRC is associated with poor survival and highly expressed in liver metastases. Claudin-2 also promotes breast cancer liver metastasis by enabling seeding and cancer cell survival. These observations support Claudin-2 as a potential therapeutic target for managing patients with liver metastases. Antibody-drug conjugates (ADC) are promising antitumor therapeutics, which combine the specific targeting ability of monoclonal antibodies with the potent cell killing activity of cytotoxic drugs. Herein, we report the generation of 28 anti-Claudin-2 antibodies for which the binding specificities, cross-reactivity with claudin family members, and cross-species reactivity were assessed by flow cytometry analysis. Multiple drug conjugates were tested, and PNU was selected for conjugation with anti-Claudin-2 antibodies binding either extracellular loop 1 or 2. Anti-Claudin-2 ADCs were efficiently internalized and were effective at killing Claudin-2-expressing CRC cancer cells in vitro. Importantly, PNU-conjugated-anti-Claudin-2 ADCs impaired the development of replacement-type CRC liver metastases in vivo, using established CRC cell lines and patient-derived xenograft (PDX) models of CRC liver metastases. Results suggest that the development of ADCs targeting Claudin-2 is a promising therapeutic strategy for managing patients with CRC liver-metastatic disease who present replacement-type liver metastases.

Polo-like kinase 1 (PLK1) inhibitors have had limited antitumor efficacy as single agents, and focus of current efforts is on combination therapies. We initially confirmed that the PLK1-specific inhibitor onvansertib (ONV) could enhance responses to a PARP inhibitor (olaparib) in prostate cancer xenografts. To identify more effective combinations, we screened a library of bioactive compounds for efficacy in combination with ONV in LNCaP prostate cancer cells, which identified a series of compounds including multiple AKT inhibitors. We confirmed in vitro synergy between ONV and the AKT inhibitor ipatasertib (IPA) and found that the combination increased apoptosis. Mechanistic studies showed that ONV increased expression of the antiapoptotic protein SURVIVIN and that this was mitigated by IPA. Studies in three PTEN-deficient prostate cancer xenograft models showed that cotreatment with IPA and ONV led to significant tumor growth inhibition compared with monotherapies. Together, these in vitro and in vivo studies demonstrate that the efficacy of PLK1 antagonists can be enhanced by PARP or AKT inhibition and support further development of these combination therapies.

AB598 is a CD39 inhibitory antibody being pursued for the treatment of solid tumors in combination with chemotherapy and immunotherapy. CD39 metabolizes extracellular adenosine triphosphate (eATP), an alarmin capable of promoting antitumor immune responses, into adenosine, an immuno-inhibitory metabolite. By inhibiting CD39, the consumption of eATP is reduced, resulting in a proinflammatory milieu in which eATP can activate myeloid cells to promote antitumor immunity. The preclinical characterization of AB598 provides a mechanistic rationale for combining AB598 with chemotherapy in the clinic. Chemotherapy can induce ATP release from tumor cells and, when preserved by AB598, both chemotherapy-induced eATP and exogenously added ATP promote the function of monocyte-derived dendritic cells via P2Y11 signaling. Inhibition of CD39 in the presence of ATP can promote inflammasome activation in in vitro-derived macrophages, an effect mediated by P2X7. In a MOLP8 murine xenograft model, AB598 results in full inhibition of intratumoral CD39 enzymatic activity, an increase in intratumoral ATP, a decrease of extracellular CD39 on tumor cells, and ultimately, control of tumor growth. In cynomolgus monkeys, systemic dosing of AB598 results in effective enzymatic inhibition in tissues, full peripheral and tissue target engagement, and a reduction in cell surface CD39 both in tissues and in the periphery. Taken together, these data support a promising therapeutic strategy of harnessing the eATP generated by standard-of-care chemotherapies to prime the tumor microenvironment for a productive antitumor immune response.

Delta-like ligand 3 (DLL3) is overexpressed in small cell lung cancer (SCLC) and has been considered an attractive target for SCLC therapy. Rovalpituzumab tesirine was the first DLL3-targeted antibody-drug conjugate (ADC) to enter clinical studies. However, serious adverse events limited progress in the treatment of SCLC with rovalpituzumab tesirine. In this study, we developed a novel DLL3-targeted ADC, FZ-AD005, by using DXd with potent cytotoxicity and a relatively better safety profile to maximize the therapeutic index. FZ-AD005 was generated by a novel anti-DLL3 antibody, FZ-A038, and a valine-alanine (Val-Ala) dipeptide linker to conjugate DXd. Moreover, Fc-silencing technology was introduced in FZ-AD005 to avoid off-target toxicity mediated by FcγRs and showed negligible Fc-mediated effector functions in vitro. In preclinical evaluation, FZ-AD005 exhibited DLL3-specific binding and demonstrated efficient internalization, bystander killing, and excellent in vivo antitumor activities in cell line-derived xenograft and patient-derived xenograft models. FZ-AD005 was stable in circulation with acceptable pharmacokinetic profiles in cynomolgus monkeys. FZ-AD005 was well tolerated in rats and monkeys. The safety profile of FZ-AD005 was favorable, and the highest nonseverely toxic dose was 30 mg/kg in cynomolgus monkeys. In conclusion, FZ-AD005 has the potential to be a superior DLL3-targeted ADC with a wide therapeutic window and is expected to provide clinical benefits for the treatment of patients with SCLC.

The enhanced permeability and retention (EPR) effect controls passive nanodrug uptake in tumors, and may provide a high tumor payload with prolonged retention for cancer treatment. However, EPR-mediated tumor uptake and distribution vary by cancer phenotype. Thus, we hypothesized that a companion PET-imaging surrogate may benefit EPR-mediated therapeutic drug delivery. We developed two 89Zr-radiolabeled nanocarriers based on 4-armed-starPEG40kDa with or without talazoparib (TLZ), a potent PARPi, as surrogates for the PEG-TLZ4 therapeutic scaffold. For PET imaging, PEG-DFB4 and PEG-DFB1-TLZ3 were radiolabeled with 89Zr by replacing one or all four TLZ on PEG-TLZ4 with deferoxamine B (DFB). The radiolabeled nanodrugs [89Zr]PEG-DFB4 and [89Zr]PEG-DFB1-TLZ3 were tested in vivo in prostate cancer subcutaneous xenografts (22Rv1, LTL-545, and LTL-610) and 22Rv1 metastatic models. Their EPR-mediated tumoral uptake and penetration was compared to CT26, a known EPR-high MicroPET/CT images, organ biodistribution, and calculated kinetic parameters showed high uptake in CT26 and LTL-545, moderate to low uptake in LTL-610 and 22Rv1. MicroPET/CT and high-resolution autoradiographic images showed nanocarrier penetration into highly permeable CT26, but heterogeneous peripheral accumulation was observed in LTL-545, LTL-610, and 22Rv1 subcutaneous xenografts and metastatic tumors. CD31 staining of tumor sections showed homogenous vascular development in CT26 tumors and heterogeneity in other xenografts. Both [89Zr]PEG-DFB4 and [89Zr]PEG-DFB1-TLZ3 showed similar accumulation and distribution in subcutaneous and metastatic tumor models. Both nanocarriers can measure tumor model passive uptake heterogeneity. Although heterogeneous, prostate cancer xenografts had low EPR. These starPEG nanocarriers could be used as PET imaging surrogates to predict drug delivery and efficacy.

Small molecule inhibitors of the mono (ADP) ribosyl transferase PARP7 are being evaluated as a monotherapy for tumors overexpressing PARP7 and in combination with immune checkpoint blockade. We previously showed that sensitivity to the PARP7 inhibitor (PARP7i) RBN-2397 could be enhanced by co-treatment with agonists of the Aryl Hydrocarbon Receptor (AHRa) in cell lines that show strong intrinsic sensitivity to RBN-2397. Here we demonstrate that a range of tumor cell lines that are relatively insensitive to PARP7i or AHRa as individual agents are unexpectedly profoundly sensitive to the combination. Our data show that this synergistic response is dependent on AHR/ARNT and is associated with increased levels of nuclear AHR and increased transcription of AHR target genes. In some hormone receptor-positive cell lines, we find that combination treatment is associated with proteasomal turnover of the steroid hormone receptors, androgen receptor and estrogen receptor. Both wildtype and hormone-resistant mutant forms of these receptors are degraded upon treatment with AHRa and PARP7i in breast and prostate cancer models. These results suggest that combining PARP7i with AHRa may extend the utility of these drugs to a wider range of tumors, including those that are refractory to hormone therapy.

Glypican-3 (GPC3) is a proteoglycan with high sensitivity and specificity for hepatocellular carcinoma (HCC). We describe the integrated development and validation of a GPC3-targeting optical imaging probe and T-cell redirecting antibody (TRAB) as a theranostic strategy for the detection and treatment of HCC. A novel TRAB targeting GPC3 on HCC tumor cells and the CD3 T-cell receptor as well as a distinct GPC3-specific optical imaging probe were developed from a short peptide. The efficacy of GPC3/CD3 TRAB was evaluated in vitro using interferon-γ release and calcein-AM assays. Patient-derived xenografts (PDX) were used to assess the in vivo efficacy of GPC3/CD3 TRAB and the GPC3 imaging probe for the detection of GPC3+ HCC. GPC3/CD3 TRAB caused a dose-dependent escalation in interferon-γ release from inactive peripheral blood T-cells (P = 0.001) and higher tumor-cell lysis (P = 0.01) compared to controls in vitro. Intratumorally injected GPC3/CD3 TRAB resulted in significant prolongation of tumor doubling time in the GPC3+ PDX mice, with an associated reduction of tumor fluorescent signal from the HiLyte 488- conjugated GPC3 specific peptide on optical imaging. HCC cell targeting using a GPC3/CD3 TRAB derived from a small peptide resulted in effective T-cell activation and induction of a cytotoxic response toward GPC3+ HCC tumor cells both in vitro and in vivo. GPC3-specific optical imaging enabled the detection of the GPC3+ HCC cells and noninvasive monitoring of tumor response to adoptive immunotherapy. The integrated development of a targeted therapeutic and molecular imaging probe provides a novel paradigm for developing cancer theranostics.

Pancreatic ductal adenocarcinoma (PDAC) stands out as one of the most aggressive and challenging tumors, characterized by a bleak prognosis with a mere 11% survival rate over five years in the United States. Its formidable nature is primarily attributed to its highly aggressive behavior and poor response to existing therapies. PDAC, being notably resistant to immune interventions, presents a significant obstacle in treatment strategies. While immune checkpoint inhibitor therapies have revolutionized outcomes for various cancers, their efficacy in PDAC remains exceedingly low, benefiting less than 1% of patients. The consistent failure of these therapies in PDAC has prompted intensive investigation, particularly at the preclinical level, to unravel the intricate mechanisms of resistance inherent in this cancer type. This pursuit aims to pave the way for the development of novel immunotherapeutic strategies tailored to the distinct characteristics of PDAC. This review endeavors to provide a comprehensive exploration of these emerging immunotherapy approaches in PDAC, with a specific emphasis on elucidating their underlying immunological mechanisms. Additionally, it sheds light on recently identified factors driving resistance to immunotherapy and evasion of the immune system in PDAC, offering insights beyond the conventional drivers that have been extensively studied.

T-cell activation is a multistep process requiring T-cell receptor engagement by peptide-major histocompatibility complexes (Signal 1) coupled with CD28-mediated costimulation (Signal 2). Tumors typically lack expression of CD28 ligands, so tumor-specific Signal 1 (e.g., neoepitope presentation) without costimulation may be ineffective or even induce T-cell anergy. We designed the bispecific antibody XmAb808 to co-engage the tumor-associated antigen B7-H3 with CD28 to promote T-cell costimulation within the tumor microenvironment. XmAb808 costimulation was measured by its ability to activate and expand T cells and enhance T cell-mediated cancer cell killing in cocultures of human peripheral blood mononuclear cells (PBMCs) and cancer cells, and in mice engrafted with human PBMCs and tumor xenografts. XmAb808 avidly bound cancer cells and stimulated interleukin (IL)2 and interferon (IFN)γ secretion from T cells cocultured with cancer cells engineered to deliver Signal 1 to T cells via a surface-expressed anti-CD3 antibody. XmAb808 enhanced expression of the anti-apoptotic factor Bcl-xL and CD25, promoting survival and IL2-dependent expansion of T cells coupled with increased T cell-mediated cytotoxicity in vitro. XmAb808 combined with a EpCAM×CD3 bispecific antibody to enhance target cell killing through IL2-dependent expansion of CD25+ T cells. This combination also suppressed pancreatic tumor xenograft growth in mice. Further, XmAb808 combined with an anti-PD1 antibody to suppress breast tumor xenograft growth in mice. XmAb808 as monotherapy and in combination with an anti-PD1 antibody is currently in clinical development in patients with advanced solid tumors. Our results suggest that XmAb808 may also combine with tumor antigen-targeted anti-CD3 (Signal 1) T-cell engagers.

Despite notable progress in the treatment of advanced head and neck squamous cell carcinoma (HNSCC), survival remains poor in patients with recurrent and/or metastatic (R/M) human papillomavirus (HPV)-negative HNSCC. Worse outcomes in the HPV-negative patients may be partly related to loss of cell-cycle regulators and tumor suppressors as well as a noninflamed and hypoxic tumor microenvironment, both of which contribute to treatment resistance and disease progression. Anti-programmed cell death protein 1-based regimens as current standard-of-care treatment for R/M HNSCC are associated with durable responses in a limited number of patients. The anti-epidermal growth factor receptor (EGFR) monoclonal antibody, cetuximab, has antitumor activity in this treatment setting, but responses are short-lived and inevitably curtailed due to treatment resistance. Crosstalk between the EGFR and hepatocyte growth factor (HGF)-dependent mesenchymal-epithelial transition (c-MET) receptor tyrosine kinase pathway is a known mechanism of resistance to cetuximab. Dual targeting of EGFR and c-MET pathways may overcome resistance to cetuximab in patients with HPV-negative HNSCC. Here, we review clinical data of treatments evaluated in patients with R/M HPV-negative HNSCC and highlight the potential role of combining HGF/c-MET and EGFR pathway inhibitors to overcome cetuximab resistance in this population.