Discovery of C-Linked Nucleoside Analogues with Antiviral Activity against SARS-CoV-2.

The recent COVID-19 pandemic underscored the limitations of currently available direct-acting antiviral treatments against acute respiratory RNA-viral infections and stimulated major research initiatives targeting anticoronavirus agents. Two novel nsp5 protease (MPro) inhibitors have been approved, nirmatrelvir and ensitrelvir, along with two existing nucleos(t)ide analogues repurposed as nsp12 polymerase inhibitors, remdesivir and molnupiravir, but a need still exists for therapies with improved potency and systemic exposure with oral dosing, better metabolic stability, and reduced resistance and toxicity risks. Herein, we summarize our research toward identifying nsp12 inhibitors that led to nucleoside analogues 10e and 10n, which showed favorable pan-coronavirus activity in cell-infection screens, were metabolized to active triphosphate nucleotides in cell-incubation studies, and demonstrated target (nsp12) engagement in biochemical assays.

SEMA3C Supports Pancreatic Cancer Progression by Regulating the Autophagy Process and Tumor Immune Microenvironment.

To date, driver genes for pancreatic cancer treatment are difficult to pursue therapeutically. Targeting mutated KRAS, the most renowned driver gene in pancreatic cancer, is an active area of study. We discovered a gene named SEMA3C was highly expressed in pancreatic cancer cell lines and patients with a G12D mutation in KRAS. High expression of SEMA3C in patients was significantly associated with the decreased survival of pancreatic cancer patients based on the TCGA database. In pancreatic cancer cells, SEMA3C knockdown or inhibition exhibited growth/colony inhibition and cell cycle arrest. In addition, SEMA3C inhibition sensitized KRAS or MEK1/2 inhibition in pancreatic cancer cells. Overexpression of SEMA3C resulted in the induction of autophagy, whereas depletion of SEMA3C compromised induction of autophagy. SEMA3C modified the PD-L1 expression in tumor and immune cells and is correlated with the M2-like macrophage marker ARG1/CD163 expression, which could reshape the tumor microenvironment. Inhibition of SEMA3C decreased tumor formation in the xenograft model in vivo. Taken together, our data suggest that SEMA3C plays a substantial role in promoting cancer cell survival by regulating the autophagy process and impacting the tumor environment immune response. SEMA3C can be used as a novel target or marker with therapeutic or diagnostic potential in pancreatic cancer especially in tumors harboring the specific KRAS G12D mutation.

Evaluation of Phenol-Substituted Diphyllin Derivatives as Selective Antagonists for Ebola Virus Entry.

Ebola virus (EBOV) is an aggressive filoviral pathogen that can induce severe hemorrhagic fever in humans with up to 90% fatality rate. To date, there are no clinically effective small-molecule drugs for postexposure therapies to treat filoviral infections. EBOV cellular entry and infection involve uptake via macropinocytosis, navigation through the endocytic pathway, and pH-dependent escape into the cytoplasm. We report the inhibition of EBOV cell entry via selective inhibition of vacuolar (V)-ATPase by a new series of phenol-substituted derivatives of the natural product scaffold diphyllin. In cells challenged with Ebola virus, the diphyllin derivatives inhibit viral entry dependent upon structural variations to low nanomolar potencies. Mechanistically, the diphyllin derivatives had no effect on uptake and colocalization of viral particles with endocytic marker LAMP1 but directly modulated endosomal pH. The most potent effects were reversible exhibiting higher selectivity than bafilomycin or the parent diphyllin. Unlike general lysosomotrophic agents, the diphyllin derivatives showed no major disruptions of endocytic populations or morphology when examined with Rab5 and LAMP1 markers. The dilated vacuole phenotype induced by apilimod treatment or in constitutively active Rab5 mutant Q79L-expressing cells was both blocked and reversed by the diphyllin derivatives. The results are consistent with the action of the diphyllin scaffold as a selective pH-dependent viral entry block in late endosomes. Overall, the compounds show improved selectivity and minimal cytotoxicity relative to classical endosomal acidification blocking agents.

Single Small Molecule-Assembled Mitochondria Targeting Nanofibers for Enhanced Photodynamic Cancer Therapy in Vivo.

Photodynamic therapy (PDT) has emerged as an attractive alternative in cancer therapy, but its therapeutic effects are limited by the nonselective subcellular localization and poor intratumoral retention of small-molecule photosensitizes. Here a fiber-forming nanophotosensitizer (PQC NF) that is composed of mitochondria targeting small molecules of amphiphilicity is reported. Harnessing the specific mitochondria targeting, the light-activated PQC NFs produce approximately 110-fold higher amount of reactive oxygen species (ROS) in cells than free photosensitizers and can dramatically induce mitochondrial disruption to trigger intense apoptosis, showing 20-50 times better in vitro anticancer potency than traditional photosensitizers. As fiber-shaped nanomaterials, PQC NFs also demonstrated a long-term retention in tumor sites, solving the challenge of rapid clearance of small-molecule photosensitizers from tumors. With these advantages, PQC NFs achieve a 100% complete cure rate in both subcutaneous and orthotopic oral cancer models with the administration of only a single dose. This type of single small molecule-assembled mitochondria targeting nanofibers offer an advantageous strategy to improve the in vivo therapeutic effects of conventional PDT.

Iron-crosslinked Rososome with robust stability and high drug loading for synergistic cancer therapy.

Development of liposomal nanomedicine with robust stability, high drug loading and synergistic efficacy is a promising strategy for effective cancer therapy. Here, we present an iron-crosslinked rosmarinic liposome (Rososome) which can load high contents of drugs (including 25.8% rosmarinic acid and 9.04% doxorubicin), keep stable in a high concentration of anionic detergent and exhibit synergistic anti-cancer efficacy. The Rososomes were constructed by rosmarinic acid-lipid conjugates which not only work synergistically with doxorubicin by producing reactive oxygen species but also provide catechol moieties for the iron cross-linkages. The cross-linkages can lock the payloads tightly, endowing the crosslinked Rososome with better stability and pharmacokinetics than its non-crosslinked counterpart. On the syngeneic mouse model of breast cancer, the iron-crosslinked Rososomes exhibit better anticancer efficacy than free rosmarinic acid, doxorubicin, non-crosslinked Rososome and commercial liposomal formulation of doxorubicin (DOXIL). This study introduces a novel strategy for the development of liposomes with robust stability, high drug loading and synergistic anti-cancer efficacy.

Pharmacophore hybridisation and nanoscale assembly to discover self-delivering lysosomotropic new-chemical entities for cancer therapy.

Integration of the unique advantages of the fields of drug discovery and drug delivery is invaluable for the advancement of drug development. Here we propose a self-delivering one-component new-chemical-entity nanomedicine (ONN) strategy to improve cancer therapy through incorporation of the self-assembly principle into drug design. A lysosomotropic detergent (MSDH) and an autophagy inhibitor (Lys05) are hybridised to develop bisaminoquinoline derivatives that can intrinsically form nanoassemblies. The selected BAQ12 and BAQ13 ONNs are highly effective in inducing lysosomal disruption, lysosomal dysfunction and autophagy blockade and exhibit 30-fold higher antiproliferative activity than hydroxychloroquine used in clinical trials. These single-drug nanoparticles demonstrate excellent pharmacokinetic and toxicological profiles and dramatic antitumour efficacy in vivo. In addition, they are able to encapsulate and deliver additional drugs to tumour sites and are thus promising agents for autophagy inhibition-based combination therapy. Given their transdisciplinary advantages, these BAQ ONNs have enormous potential to improve cancer therapy.

A nephrotoxicity-free, iron-based contrast agent for magnetic resonance imaging of tumors.

Gadolinium-based contrast agents (GBCAs) are the most widely used T1 contrast agents for magnetic resonance imaging (MRI) and have achieved remarkable success in clinical cancer diagnosis. However, GBCAs could cause severe nephrogenic systemic fibrosis to patients with renal insufficiency. Nevertheless, GBCAs are quickly excreted from the kidneys, which shortens their imaging window and prevents long-term monitoring of the disease per injection. Herein, a nephrotoxicity-free T1 MRI contrast agent is developed by coordinating ferric iron into a telodendritic, micellar nanostructure. This new nano-enabled, iron-based contrast agent (nIBCA) not only can reduce the renal accumulation and relieve the kidney burden, but also exhibit a significantly higher tumor to noise ratio (TNR) for cancer diagnosis. In comparison with Magnevist (a clinical-used GBCA), Magnevist induces obvious nephrotoxicity while nIBCA does not, indicating that such a novel contrast agent may be applicable to renally compromised patients requiring a contrast-enhanced MRI. The nIBCA could precisely image subcutaneous brain tumors in a mouse model and the effective imaging window lasted for at least 24 h. The nIBCA also precisely highlights the intracranial brain tumor with high TNR. The nIBCA presents a potential alternative to GBCAs as it has superior biocompatibility, high TNR and effective imaging window.

Recent advances on small-molecule nanomedicines for cancer treatment.

Nanomedicines have made important contributions in the development of cancer therapies due to their tumor selectivity, multifunctionality, and synergistic effect between the payloads. In addition to the required pharmaceutical ingredients, nanomedicines are generally composed of nonpharmaceutical excipients. These excipients generally form a large proportion of the nanomedicine, and they may have potential toxicity and greatly increase the cost for drug development. Small molecule nanomedicines (SMNs) minimize or abandon the excipients and are directly assembled from pharmaceutical ingredients, which can largely improve the drug delivery efficiency and biosafety while also relieving the financial burden of drug development. In this review, we summarize recently developed SMNs that are composed of a single drug, physical mixtures of multiple drugs, drug-drug covalent conjugates, dyes with drugs, photosensitizers with drugs, photosensitizers with peptides, and drugs with peptides. This review focuses on the SMN's applications in cancer treatments, their limitations, and the future development outlook of SMNs. We hope that our insights on SMNs may be helpful to the future of drug development and make nanomedicine more powerful in the battle with cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Peptide-based materials for cancer immunotherapy.

Peptide-based materials hold great promise as immunotherapeutic agents for the treatment of many malignant cancers. Extensive studies have focused on the development of peptide-based cancer vaccines and delivery systems by mimicking the functional domains of proteins with highly specific immuno-regulatory functions or tumor cells fate controls. However, a systemic understanding of the interactions between the different peptides and immune systems remains unknown. This review describes the role of peptides in regulating the functions of the innate and adaptive immune systems and provides a comprehensive focus on the design, categories, and applications of peptide-based cancer vaccines. By elucidating the impacts of peptide length and formulations on their immunogenicity, peptide-based immunomodulating agents can be better utilized and dramatic breakthroughs may also be realized. Moreover, some critical challenges for translating peptides into large-scale synthesis, safe delivery, and efficient cancer immunotherapy are posed to improve the next-generation peptide-based immunotherapy.

Porphyrin-Based Nanomedicines for Cancer Treatment.

As unique molecules with both therapeutic and diagnostic properties, porphyrin derivatives have been extensively employed for cancer treatment. Porphyrins not only show powerful phototherapeutic effects (photodynamic and photothermal therapies), but also exhibit excellent imaging capacities, such as near-infrared fluorescent imaging (NIRFI), magnetic resonance imaging (MRI), photoacoustic imaging (PAI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT). In order to take advantage of their robust phototherapeutic effects and excellent imaging capacities, porphyrins can be used to create nanomedicines with effective therapeutic and precise diagnostic properties for cancer treatment. In this Review, we summarize porphyrin-based nanomedicines which have been developed recently, including porphyrin-based liposomes, micelles, polymeric nanoparticles, peptide nanoparticles, and small-molecule nanoassemblies, and their applications on cancer therapy and diagnosis. The outlook and limitation of porphyrin-based nanomedicines are also reviewed.

Phenotypic Prioritization of Diphyllin Derivatives That Block Filoviral Cell Entry by Vacuolar (H+ )-ATPase Inhibition.

Many viruses use endosomal pathways to gain entry into cells and propagate infection. Sensing of endosomal acidification is a trigger for the release of many virus cores into the cell cytosol. Previous efforts with inhibitors of vacuolar ATPase have been shown to block endosomal acidification and affect viral entry, albeit with limited potential for therapeutic selectivity. In this study, four novel series of derivatives of the vacuolar ATPase inhibitor diphyllin were synthesized to assess their potential for enhancing potency and anti-filoviral activity over cytotoxicity. Derivatives that suitably blocked cellular entry of Ebola pseudotyped virus were further evaluated as inhibitors of endosomal acidification and isolated human vacuolar ATPase activity. Several compounds with significant increases in potency over diphyllin in these assays also separated from cytotoxic doses in human cell models by >100-fold. Finally, three derivatives were shown to be inhibitors of replication-competent Ebola viral entry into primary macrophages with similar potencies and enhanced selectivity toward antiviral activity.

Large-Scale Screening and Identification of Novel Ebola Virus and Marburg Virus Entry Inhibitors.

Filoviruses are highly infectious, and no FDA-approved drug therapy for filovirus infection is available. Most work to find a treatment has involved only a few strains of Ebola virus and testing of relatively small drug libraries or compounds that have shown efficacy against other virus types. Here we report the findings of a high-throughput screening of 319,855 small molecules from the Molecular Libraries Small Molecule Repository library for their activities against Marburg virus and Ebola virus. Nine of the most potent, novel compounds that blocked infection by both viruses were analyzed in detail for their mechanisms of action. The compounds inhibited known key steps in the Ebola virus infection mechanism by blocking either cell surface attachment, macropinocytosis-mediated uptake, or endosomal trafficking. To date, very few specific inhibitors of macropinocytosis have been reported. The 2 novel macropinocytosis inhibitors are more potent inhibitors of Ebola virus infection and less toxic than ethylisopropylamiloride, one commonly accepted macropinocytosis inhibitor. Each compound blocked infection of primary human macrophages, indicating their potential to be developed as new antifiloviral therapies.