Stapled SC34EK fusion inhibitors with high potency against HIV-1and improved protease resistance

HIV fusion inhibitors are promising therapeutic agents for AIDS treatment. One fusion inhibitor has been approved as anti-HIV drug, while more of them are in preclinical studies or clinical trials. Highly active fusion inhibitors with excellent pharmacokinetic properties are still needed for development of anti-HIV drugs. We found that all-hydrocarbon staples inserted in SC34 EK could not only enhance the inhibitory activity of inhibitors against HIV-1, but also improve protease resistance. Further study revealed that SC34 EK-1 containing a staple was a potent fusion inhibitor with IC;value of 0.04-6.4 nmol/L towards diverse HIV-1 subtypes and half-life value of 112 min against protease hydrolysis. X-ray crystallography studies indicated that introduction of a hydrocarbon staple in SC34 EK could make the amino acid at the interaction surface form perfect conformation to promote inhibitor peptide interacting with target.

Paradigm shift of chemotherapy and systemic treatment for biliary tract cancer

Biliary tract cancers(BTC)are frequently identified at late stages and have a poor prognosis due to limited systemic treatment regimens.For more than a decade,the combination of gemcitabine and cis-platin has served as the first-line standard treatment.There are few choices for second-line chemo-therapy.Targeted treatment with fibroblast growth factor receptor 2 inhibitors,neurotrophic tyrosine receptor kinase inhibitors,and isocitrate dehydrogenase 1 inhibitors has had important results.Immune checkpoint inhibitors(ICI)such as pembrolizumab are only used in first-line treatment for microsatellite instability high patients.The TOPAZ-1 trial's outcome is encouraging,and there are several trials underway that might soon put targeted treatment and ICI combos into first-line options.Newer targets and agents for existing goals are being studied,which may represent a paradigm shift in BTC management.Due to a scarcity of targetable mutations and the higher toxicity profile of the current medications,the new category of drugs may occupy a significant role in BTC therapies.

Systemic treatment in EGFR-ALK NSCLC patients:second line therapy and beyond

Lung cancer is the most frequently diagnosed cancer and a leading cause of cancer mortality worldwide, with adenocarcinoma being the most common histological subtype. Deeper understanding of the pathobiology of non-small cell lung cancer(NSCLC) has led to the development of small molecules that target genetic mutations known to play critical roles in progression to metastatic disease and to influence response to targeted therapies. The principle goal of precision medicine is to define those patient populations most likely to respond to targeted therapies. However, the cancer genome landscape is composed of relatively few "mountains" [representing the most commonly mutated genes like KRAS, epidermal growth factor(EGFR), and anaplastic lymphoma kinase(ALK)] and a vast number of "hills"(representing low frequency but potentially actionable mutations). Low-frequency lesions that affect a druggable gene product allow a relatively small population of cancer patients for targeted therapy to be selected.

Efficacy and safety of the long-acting fusion inhibitor albuvirtide in antiretroviral-experienced adults with human immunodeficiency virus-1:interim analysis of the randomized,controlled,phase 3,non-inferiority TALENT study

Background:Albuvirtide is a once-weekly injectable human immunodeficiency virus(HIV)-1 fusion inhibitor.We present interim data for a phase 3 trial assessing the safety and efficacy of albuvirtide plus lopinavir-ritonavir in HIV-1-infected adults already treated with antiretroviral drugs.Methods:We carried out a 48-week,randomized,controlled,open-label non-inferiority trial at 12 sites in China.Adults on the World Health Organization(WHO)-recommended first-line treatment for>6 months with a plasma viral load>1000 copies/mL were enrolled and randomly assigned(1:1)to receive albuvirtide(once weekly)plus ritonavir-boosted lopinavir(ABT group)or the WHO-recommended second-line treatment(NRTI group).The primary endpoint was the proportion of patients with a plasma viral load below 50 copies/mL at 48 weeks.Non-inferiority was prespecified with a margin of 12%.Results:At the time of analysis,week 24 data were available for 83 and 92 patients,and week 48 data were available for 46 and 50 patients in the albuvirtide and NRTI groups,respectively.At 48 weeks,80.4%of patients in the ABT group and 66.0%of those in the NRTI group had HIV-1 RNA levels below 50 copies/mL,meeting the criteria for non-inferiority.For the per-protocol population,the superiority of albuvirtide over NRTI was demonstrated.The frequency of grade 3 to 4 adverse events was similar in the two groups;the most common adverse events were diarrhea,upper respiratory tract infections,and grade 3 to 4 increases in triglyceride concentration.Renal function was significantly more impaired at 12 weeks in the patients of the NRTI group who received tenofovir disoproxil fumarate than in those of the ABT group.Conclusions:The TALENT study is the first phase 3 trial of an injectable long-acting HIV drug.This interim analysis indicates that once-weekly albuvirtide in combination with ritonavir-boosted lopinavir is well tolerated and non-inferior to the WHO-recommended second-line regimen in patients with first-line treatment failure.Trial registration:ClinicalTrials.gov Identifier:NCT02369965;https://www.clinicaltrials.gov.Chinese Clinical Trial Registry No.ChiCTR-TRC-14004276;http://www.chictr.org.cn/enindex.aspx.

A highly potent and stable pan-coronavirus fusion inhibitor as a candidate prophylactic and therapeutic for COVID-19 and other coronavirus diseases

The development of broad-spectrum antivirals against human coronaviruses(HCoVs)is critical to combat the current coronavirus disease 2019(COVID-19)pandemic caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)and its variants,as well as future outbreaks of emerging CoVs.We have previously identified a polyethylene glycol-conjugated(PEGylated)lipopeptide,EK1C4,with potent pan-CoV fusion inhibitory activity.However,PEG linkers in peptide or protein drugs may reduce stability or induce anti-PEG antibodies in vivo.Therefore,we herein report the design and synthesis of a series of dePEGylated lipopeptide-based pan-CoV fusion inhibitors featuring the replacement of the PEG linker with amino acids in the heptad repeat 2 C-terminal fragment(HR2-CF)of HCoV-OC43.Among these lipopeptides,EKL1C showed the most potent inhibitory activity against infection by SARS-CoV-2 and its spike(S)mutants,as well as other HCoVs and some bat SARS-related coronaviruses(SARSr-CoVs)tested.The dePEGylated lipopeptide EKL1C exhibited significantly stronger resistance to proteolytic enzymes,better metabolic stability in mouse serum,higher thermostability than the PEGylated lipopeptide EK1C4,suggesting that EKL1C could be further developed as a candidate prophylactic and therapeutic for COVID-19 and other coronavirus diseases.

HR121 targeting HR2 domain in S2 subunit of spike protein can serve as a broad-spectrum SARS-CoV-2 inhibitor via intranasal administration

The continuously emerging SARS-CoV-2 variants pose a great challenge to the efficacy of current drugs,this necessitates the development of broad-spectrum antiviral drugs.In the previous study,we designed a recombinant protein,heptad repeat(HR)121,as a variant-proof vaccine.Here,we found it can act as a fusion inhibitor and demonstrated broadly neutralizing activities against SARS-CoV-2 and its main variants.Structure analysis suggested that HR121 targets the HR2 domain in SARS-CoV-2 spike(S)2 subunit to block virus-cell fusion.Functional experiments demonstrated that HR121 can bind HR2 at serological-pH and endosomal-pH,highlighting its inhibition capacity when SARS-CoV-2 enters via either cellular membrane fusion or endosomal route.Importantly,HR121 can effectively inhibit SARS-CoV-2 and Omicron variant pseudoviruses entering the cells,as well as block authentic SARSCoV-2 and Omicron BA.2 replications in human pulmonary alveolar epithelial cells.After intranasal administration to Syrian golden hamsters,it can protect hamsters from SARS-CoV-2 and Omicron BA.2 infection.Together,our results suggest that HR121 is a potent drug candidate with broadly neutralizing activities against SARS-CoV-2 and its variants.

A pan-coronavirus peptide inhibitor prevents SARS-CoV-2 infection in mice by intranasal delivery

Coronaviruses(Co Vs)have brought serious threats to humans,particularly severe acute respiratory syndrome coronavirus 2(SARS-Co V-2),which continually evolves into multiple variants.These variants,especially Omicron,reportedly escape therapeutic antibodies and vaccines,indicating an urgent need for new antivirals with pan-SARS-Co V-2 inhibitory activity.We previously reported that a peptide fusion inhibitor,P3,targeting heptad repeated-1(HR1)of SARS-Co V-2 spike(S)protein,could inhibit viral infections.Here,we further designed multiple derivatives of the P3 based on structural analysis and found that one derivative,the P315V3,showed the most efficient antiviral activity against SARS-Co V-2 variants and several other sarbecoviruses,as well as other human-Co Vs(HCo Vs).P315V3 also exhibited effective prophylactic efficacy against the SARS-Co V-2 Delta and Omicron variants in mice via intranasal administration.These results suggest that P315V3,which is in PhaseⅡclinical trial,is promising for further development as a nasal pan-SARS-Co V-2 or pan-Co Vs inhibitor to prevent or treat CoV diseases.

Targeting autophagy with small molecules for cancer therapy

Autophagy is a conserved lysosomal-dependent catabolic process that maintains the cellular homeostasis by recycling misfolded proteins and damaged organelles. It involves a series of ordered events (initiation, nucleation, elongation, lysosomal fusion and degradation) that are tightly regulated/controlled by diverse cell signals and stress. It is like a double-edged sword that can play either a protective or destructive role in cancer, by pro-survival or apoptotic cues. Recently, modulating autophagy by pharmacological agents has become an attractive strategy to treat cancer. Currently, a number of small molecules that inhibit autophagy initiation (e.g., ULK kinase inhibitors), nucleation (e.g., Vps34 inhibitors), elongation (e.g., ATG4 inhibitors) and lysosome fusion (e.g., chloroquine, hydroxyl chloroquine,etc.) are reported in pre-clinical and clinical study. Also a number of small molecules reported to induce autophagy by targeting mammalian target of rapamycin (e.g., rapamycin analogs) or adenosine 5'-monophosphate-activated protein kinase (e.g., sulforaphane). The study results suggest that many potential "druggable" targets exist in the autophagy pathway that could be harnessed for developing new cancer therapeutics. In this review, we discuss the reported autophagy modulators (inhibitors and inducers), their molecular mode of action and their applications in cancer therapy.

Identification of the dietary supplement capsaicin as an inhibitor of Lassa virus entry

The limited treatment options for the increasing occurrence of Lassa hemorrhagic fever in West Africa poses an urgent need for the discovery and development of novel therapeutics.Dietary supplements,especially natural products that are edible and safe for human use,are a good source of drug discovery with potential for uncovering novel applications,In this study,we tested 40 natural products of dietary supplements and identified capsaicin,a common dietary supplement abundant in chili peppers,as an inhibitor of Lassa virus(LASV)entry with EC5,of 6.9-10.0μmol/L using an HIV based pseudo virus platform.Capsaicin inhibits the entry of five LASV strains but not against the Old World arenavirus lymphocytic choriomeningitis virus(LCMV),showing a preferential activity against LASV.Capsaicin inhibits LASV entry by blocking the pH dependent viral fusion through affecting the stable signal peptide(SSP)-GP2 transmembrane(GP2TM)region of the LASV surface glycoprotein.Mutational study revealed the key residues Ala25,Val431,Phe434 and Val435 in SsP-CP2TM region in capsaicin’s antiviral effect.This study for the first time reveals a direct acting antiviral effect of capsaicin against the hemorrhagic fever causing LASV,providing detailed interaction hot spots in the unique SSP-GP2TMinterface of LASV glycoprotein that is crucial in fusion inhibition,and offering a new strategy in discovering and developing antivirals from natural products that are safe for human use.

Peptide stapling with the retention of double native side-chains

All-hydrocarbon stapling strategy has been widely applied for enhancing the proteolytic stability of peptides. However, two major technical hurdles to some extent limit the development of stapled peptides for therapeutic usage: rational selection of the stapling sites and the corresponding deletion of the native side chains. Previously we described the development of the olefin-terminated amino acids with the retention of native side chains and successfully applied them in the synthesis of hydrocarbon stapled peptides with single side-chain retention. Here, we explored the feasibility and effectiveness of hydrocarbon stapling strategy characterized as double side-chains retention. Modeled after a lengthy human immunodeficiency virus-1(HIV-1) fusion inhibitor SC34 EK, Leu^(i), Ser^(i+4)and Lys^(i), Leu^(i+4)stapled peptides with the retention of double side-chains were effectively obtained. Our complementary study provided a convenient alternative to address where to install the staple in sequence for conventional all-hydrocarbon peptide stapling. Furthermore, this method not only conferred conformational reinforcement for SC34 EK with high α-helicity and protease resistance, but also preserved the structural characteristic(key peripheral residues, charge and solubility) of the linear peptide to the maximum, which are crucial for anti-HIV-1 activity.