Generation and structure-activity relationships of novel imidazo-thienopyridine based TLR7 agonists: application as payloads for immunostimulatory antibody drug-conjugates.

Pairing immunostimulatory small molecules with the targeting capability of an antibody has emerged as a novel therapeutic modality with the potential to treat a variety of solid tumors. A series of compounds based on an imidazo-thienopyridine scaffold were synthesized and tested for their ability to agonize the innate immune sensors toll-like receptor 7 and 8 (TLR7/8). Structure-activity relationship (SAR) studies revealed that certain simple amino-substituents could enable TLR7 agonism at low nanomolar concentrations. Drug-linkers containing either payload 1 or 20h were conjugated to the HER2-targeting antibody trastuzumab at the interchain disulfide cysteine residues using a cleavable valine-citrulline dipeptide linker and stochastic thiol-maleimide chemistry. In vitro, these immune-stimulating antibody drug-conjugates (ADCs) were found to induce cytokine release in a murine splenocyte assay when co-cultured with the HER2-high NCI-N87 cancer cell line. In vivo, tumor regression was observed with a single dose in an NCI-N87 gastric carcinoma xenograft model in BALB/c nude mice.

An easily accessible, lower rim substituted calix[4]arene selectively binds N,N-dimethyllysine.

Post-translational modifications (PTMs) are critical controllers of protein functions. One set of important PTMs are N-methylated side chains of lysine and arginine, which exist in several functionally distinct forms. Multiple groups have demonstrated the selective binding of the most hydrophobic family member, trimethyllysine (Kme3), using various macrocyclic hosts, but the selective binding of lower methylation states remains challenging. Herein we report that the installation of a sulfonate ester on the lower rim phenol of p-sulfonatocalix[4]arene efficiently generates a potent, N,N-dimethyllysine (Kme2)-selective host in one step from commercially available starting materials. We characterize its binding behaviors in solution, and examine the relationship between its unusual conformational dynamics and its guest-binding properties.

Supramolecular Affinity Chromatography for Methylation-Targeted Proteomics.

Proteome-wide studies of post-translationally methylated species using mass spectrometry are complicated by high sample diversity, competition for ionization among peptides, and mass redundancies. Antibody-based enrichment has powered methylation proteomics until now, but the reliability, pan-specificity, polyclonal nature, and stability of the available pan-specific antibodies are problematic and do not provide a standard, reliable platform for investigators. We have invented an anionic supramolecular host that can form host-guest complexes selectively with methyllysine-containing peptides and used it to create a methylysine-affinity column. The column resolves peptides on the basis of methylation-a feat impossible with a comparable commercial cation-exchange column. A proteolyzed nuclear extract was separated on the methyl-affinity column prior to standard proteomics analysis. This experiment demonstrates that such chemical methyl-affinity columns are capable of enriching and improving the analysis of methyllysine residues from complex protein mixtures. We discuss the importance of this advance in the context of biomolecule-driven enrichment methods.

Design and Evaluation of ZD06519, a Novel Camptothecin Payload for Antibody Drug Conjugates.

In recent years, the field of antibody drug conjugates (ADC) has seen a resurgence, largely driven by the clinical benefit observed in patients treated with ADCs incorporating camptothecin-based topoisomerase I inhibitor payloads. Herein, we present the development of a novel camptothecin ZD06519 (FD1), which has been specifically designed for its application as an ADC payload. A panel of camptothecin analogs with different substituents at the C-7 and C-10 positions of the camptothecin core was prepared and tested in vitro. Selected compounds spanning a range of potency and hydrophilicity were elaborated into drug-linkers, conjugated to trastuzumab, and evaluated in vitro and in vivo. ZD06519 was selected on the basis of its favorable properties as a free molecule and as an antibody conjugate, which include moderate free payload potency (∼1 nmol/L), low hydrophobicity, strong bystander activity, robust plasma stability, and high-monomeric ADC content. When conjugated to different antibodies using a clinically validated MC-GGFG-based linker, ZD06519 demonstrated impressive efficacy in multiple cell line-derived xenograft models and noteworthy tolerability in healthy mice, rats, and non-human primates.

Synthetic trimethyllysine receptors that bind histone 3, trimethyllysine 27 (H3K27me3) and disrupt its interaction with the epigenetic reader protein CBX7.

Post-translational modifications act as 'on' or 'off' switches causing downstream changes in gene transcription. Modifications such as trimethylation of lysine 27 on histone H3 (H3K27me3) cause repression of transcription and stable gene silencing, and its presence is associated with aggressive cancers of many types. We report here macrocyclic host-type compounds that can bind H3K27me3 preferentially over unmethylated H3K27, and characterize their binding affinities and selectivities using a convenient dye-displacement method. We also show that they can disrupt the protein-protein interaction of H3K27me3 with the chromobox homolog 7 (CBX7), a methyllysine reader protein, using fluorescence polarization. These results show that sub-micromolar potencies are achievable with this family of host compounds, and suggest the possibility of their use as new tools to induce the disruption of methyllysine-mediated protein-protein interactions and to report on lysine methylation in vitro.

Attraction by repulsion: compounds with like charges undergo self-assembly in water that improves in high salt and persists in real biological fluids.

We report a family of highly anionic calixarenes that form discrete homo-dimeric assemblies in pure water, that get stronger in high salt solutions, and that remain assembled in complex, denaturing solutions like real urine. The results reveal the potential of like-charged subunits for self-assembly in high-salt solutions and biological fluids.