Dharmeshkumar Patel

SAR around HBV capsid assembly modulator GLP-26.

1′-α-Cyano nucleoside analogs have emerged as key structural motifs as antiviral agents. Due to their importance, we developed a novel stereoselective synthetic route to access 1′-α-cyano carbocyclic nucleoside analogs. The strategy relies on LDA-promoted chelation-controlled enolization, which favors a highly selective Si-face six-membered transition state with paraformaldehyde, delivering the exclusive 1′-α-hydroxymethylation product. This straightforward approach proceeds without the need for metal catalysts or additional promoters, highlighting its practicality and efficiency. The resulting 1′-α-hydroxymethylation intermediate enabled the synthesis of the desired 1′-α-cyano carbocyclic pyrimidine nucleoside analogs in a stereo controlled manner. This work represents the first example of such a selective and catalyst free access to these carbocyclic scaffolds.

Approximately 250 million people are chronic HBV carriers and are at high risk of developing hepatitis, cirrhosis, and hepatocellular carcinoma. Several drugs are currently approved, but because they do not cure, lifelong therapies are the norm. HBV capsid assembly modulators (CAMs) have emerged as a promising option, as they lower several key markers of HBV replication. Novel dimeric structures (D-CAMs) were designed and evaluated. Their potency and mechanism of action were compared to those of monomeric D-CAMs, such as GLP-26. Among them, D-CAM-14 exhibited improved potency over GLP-26 and a unique effect on capsid morphology and kinetic assembly.

Yellow fever virus (YFV) is a deadly zoonotic flavivirus endemic in tropical/sub-tropical Africa and South America transmitted by mosquito vector ( Aedes aegypti ; Haemagogus leucocelaenus ) to humans and non-human primates. There are no approved antiviral agents for YFV. We previously identified 7-deaza-7-fluoro-2′-C-methyladenosine (DFA) with anti-YFV activity. Interestingly, DFA exhibits pan-activity in vitro against flaviviruses, such as dengue, Japanese encephalitis, Zika, and hepatitis C. This study aimed to expand DFA’s anti-flavivirus profile. DFA exhibited potent sub-micromolar anti-YFV activity in vitro against both the vaccine strain (YFV-17D) and a viscerotropic clinical YFV isolate (DakH1279) concomitantly with low cellular cytotoxicity and no notable mitochondrial toxicity. In vivo , efficacy was assessed against both YFV-17DD and a human clinical isolate in A129 and AG129 mouse flavivirus infection models, respectively. DFA significantly reduced virus replication in the livers of YFV-infected mice and the hallmarks of YFV-induced liver damage, including alanine transaminase levels and indocyanine green clearance. Collectively, this work identifies DFA as a potent YFV inhibitor and lays the groundwork for further therapeutic development as a YFV and, potentially, pan-flavivirus therapeutic.

Most repurposed drugs have proved ineffective for treating COVID-19. We evaluated median effective and toxic concentrations (EC₅₀, CC₅₀) of 49 drugs, mostly from previous clinical trials, in Vero cells. Ratios of reported unbound peak plasma concentrations, (C_max)/EC₅₀, were used to predict the potential in vivo efficacy. The 20 drugs with the highest ratios were retested in human Calu-3 and Caco-2 cells, and their CC₅₀ was determined in an expanded panel of cell lines. Many of the 20 drugs with the highest ratios were inactive in human Calu-3 and Caco-2 cells. Antivirals effective in controlled clinical trials had unbound C_max/EC₅₀ ≥ 6.8 in Calu-3 or Caco-2 cells. EC₅₀ of nucleoside analogs were cell dependent. This approach and earlier availability of more relevant cultures could have reduced the number of unwarranted clinical trials.

Hepatitis B virus (HBV) is the leading cause of chronic liver pathologies worldwide. HBV nucleocapsid, a key structural component, is formed through the self-assembly of the capsid protein units. Therefore, interfering with the self-assembly process is a promising approach for the development of novel antiviral agents. Applied to HBV, this approach has led to several classes of capsid assembly modulators (CAMs). Here, we report structurally novel CAMs with moderate activity and low toxicity, discovered through a biophysics-guided approach combining docking, molecular dynamics simulations, and a series of assays with a particular emphasis on biophysical experiments. Several of the identified compounds induce the formation of aberrant capsids and inhibit HBV DNA replication in vitro, suggesting that they possess modest capsid assembly modulation effects. The synergistic computational and experimental approaches provided key insights that facilitated the identification of compounds with promising activities. The discovery of preclinical CAMs presents opportunities for subsequent optimization efforts, thereby opening new avenues for HBV inhibition.

The burden of chronic hepatitis B virus (HBV) results in almost a million deaths per year. The most common treatment for chronic hepatitis B infection is long-term nucleoside analogs (NUC) or one-year interferon-alpha (pegylated or non-pegylated) therapy before or after NUC therapy. Unfortunately, these therapies rarely result in HBV functional cure because they do not eradicate HBV from the nucleus of the hepatocytes, where the covalently closed circular DNA (cccDNA) is formed and/or where the integrated HBV DNA persists in the host genome. Hence, the search continues for novel antiviral therapies that target different steps of the HBV replication cycle to cure chronically infected HBV individuals and eliminate HBV from the liver reservoirs. The authors focus on capsid assembly modulators (CAMs). These molecules are unique because they impact not only one but several steps of HBV viral replication, including capsid assembly, capsid trafficking into the nucleus, reverse transcription, pre-genomic RNA (pgRNA), and polymerase protein co-packaging. Mono- or combination therapy, including CAMs with other HBV drugs, may potentially eliminate hepatitis B infections. Nevertheless, more data on their potential effect on HBV elimination is needed, especially when used daily for 6-12 months.