Use of PD-1 and PD-L1 inhibitors after first-line therapy in esophageal cancer patients in the US.

Introduction: Esophageal cancer (EC) makes up 3.2% of all cancers but ranks sixth among cancer-related deaths worldwide. This real-world analysis determined the use of PD-1/PD-L1 (PD[L]1) inhibitors in EC patients after receiving first-line therapy.

Cell-specific targeting by heterobivalent ligands.

Current cancer therapies exploit either differential metabolism or targeting to specific individual gene products that are overexpressed in aberrant cells. The work described herein proposes an alternative approach--to specifically target combinations of cell-surface receptors using heteromultivalent ligands ("receptor combination approach"). As a proof-of-concept that functionally unrelated receptors can be noncovalently cross-linked with high avidity and specificity, a series of heterobivalent ligands (htBVLs) were constructed from analogues of the melanocortin peptide ligand ([Nle(4), dPhe(7)]-α-MSH) and the cholecystokinin peptide ligand (CCK-8).

Solid-Phase Synthesis of Heterobivalent Ligands Targeted to Melanocortin and Cholecystokinin Receptors.

Heteromultivalency provides a route to increase binding avidity and to high specificity when compared to monovalent ligands. The enhanced specificity can potentially serve as a unique platform to develop diagnostics and therapeutics. To develop new imaging agents based upon multivalency, we employed heterobivalent constructs of optimized ligands.

Immunobiological aspects of therapeutic antibodies and related characterization approaches.

Antibody therapy is one of the fastest growing areas within the biopharmaceutical field. Immunological properties and biological activity are two of the most critical elements of a therapeutic antibody. The development and validation of analytical approaches provide an appropriate means for antibody immunological characterization, while the emergence of new technologies and advanced biological research and discovery help attain a better understanding of the mechanism of action of antibodies, and therefore facilitate the development of new therapeutic antibodies.

Synthesis and evaluation of bivalent NDP-alpha-MSH(7) peptide ligands for binding to the human melanocortin receptor 4 (hMC4R).

We demonstrate the potential utility of multivalent ligands as targeting agents for cancer imaging or therapy by determining the binding of homobivalent ligands to their corresponding receptors. This manuscript details the synthesis and evaluation of a series of bivalent ligands containing two copies of the truncated heptapeptide version of [Nle4-D-Phe7]-alpha-melanocyte stimulating hormone (NDP-alpha-MSH), referred to as MSH(7). These were connected with various semirigid linkers containing Pro-Gly repeats, with or without flexible poly(ethylene glycol) (PEGO) moieties at their termini.

Rigid linkers for bioactive peptides.

Rigid linkers of variable length were used to connect two high-affinity Nle4-D-Phe7-alpha-melanocyte stimulating hormone (NDP-alpha-MSH) or two low-affinity MSH(4) ligands. The linked peptides were synthesized by solid-phase methods. Control experiments indicate there is little or no effect of these linkers on NDP-alpha-MSH or MSH(4) binding to the human melanocortin 4 receptor (hMC4R).

Development of a lanthanide-based assay for detection of receptor-ligand interactions at the delta-opioid receptor.

A lanthanide-based assay for ligand-receptor interactions provides an attractive alternative to the traditional radiolabeled determinations in terms of sensitivity, throughput, and biohazards. We designed and tested five peptide ligands for the delta-opioid receptor that were modified with a europium (Eu)-containing chelate. These labeled ligands were tested for their binding affinities and compared with the unlabeled parental ligands.

Lanthanide-based luminescent assays for ligand-receptor interactions.

The evaluation of receptor ligand interactions is important in the field of drug discovery and development. Currently these interactions are typically measured with cumbersome (low throughput) radiolabels. Higher throughput screens are available such as fluorescent measurements of G-protein coupled receptor-induced Ca2+ increases or fluorescence anisotropy, yet these have limited applicability and/or low signal to noise.

Sequence specific recognition of DNA by tailor-made hairpin conjugates of achiral seco-cyclopropaneindoline-2-benzofurancarboxamide and pyrrole-imidazole polyamides.

Hairpin conjugates of achiral seco-cyclopropaneindoline-2-benzofurancarboxamide (achiral seco-CI-Bf) and three diamides (ImPy 1, PyIm 2, and PyPy 3, where Py is pyrrole, and Im is imidazole), linked by a gamma-aminobutyrate group, were synthesized. The sequence-specific covalent alkylation of the achiral CI moiety with adenine-N3 in the minor groove was ascertained by thermally induced DNA cleavage experiments. The results provide evidence that hairpin conjugates of achiral seco-CI-Bf-gamma-polyamides could be tailored to target specific DNA sequences according to a set of general rules: the achiral CI moiety selectively reacts with adenine-N3, a stacked pair of imidazole/benzofuran prefers a G/C base pair, and a pyrrole/benzofuran prefers an A/T or T/A base pair.

Hitting multiple targets with multimeric ligands.

Multimeric ligands consist of multiple monomeric ligands attached to a single backbone molecule, creating a multimer that can bind to multiple receptors or targets simultaneously. Numerous examples of multimeric binding exist within nature. Due to the multiple and simultaneous binding events, multimeric ligands bind with an increased affinity compared to their corresponding monomers.

Design, synthesis, and biological evaluation of achiral analogs of duocarmycin SA.

The design, synthesis, as well as biochemical and biological evaluation of two novel achiral analogs of duocarmycin SA (DUMSA), 1 and 2, are described. Like CC-1065 and adozelesin, compounds 1 and 2 covalently reacted with adenine-N3 in AT-rich sequences and led to the formation of DNA strand breaks upon heating. The cytotoxicity of compounds 1 and 2 against human cancer cells (K562, LS174T) was determined using a MTT assay giving IC(50) values in the low nanomolar.

A novel class of achiral seco-analogs of CC-1065 and the duocarmycins: design, synthesis, DNA binding, and anticancer properties.

The synthesis, DNA binding properties, and in vitro and in vivo anticancer activity of fifteen achiral seco-cyclopropylindoline (or achiral seco-CI) analogs (5a-o) of CC-1065 and the duocarmycins are described. The achiral seco-CI analogs contain a 4-hydroxyphenethyl halide moiety that is attached to a wide range of indole, benzimidazole, pyrrole, and pyridyl-containing noncovalent binding components. The 4-hydroxyphenethyl halide moiety represents the simplest mimic of the seco-cyclopropylpyrroloindoline (seco-CPI) pharmacophore found in the natural products, and it lacks a chiral center.

Lanthanide-based time-resolved fluorescence of in cyto ligand-receptor interactions.

A lanthanide-based assay for ligand-receptor interactions provides an attractive alternative to the traditional radiolabeled determinations in terms of sensitivity, throughput, and biohazards. We designed and tested peptide ligands modified with an Eu-DTPA chelate. These labeled ligands were used in competitive binding assays with results comparable to those obtained using the traditional radiolabeled binding assays.

Novel targeting strategy based on multimeric ligands for drug delivery and molecular imaging: homooligomers of alpha-MSH.

Homooligomers constructed with 4- and 6-amino acid fragments of melanocortin (alpha-MSH) bind with higher affinity and with apparent cooperativity to melanocortin receptor, compared to their constituent monomers. Individual ligands were tethered with various spacers of different length and rigidity and the influence of spacers on binding was studied. Binding assays were performed on cells transfected with the melanocortin receptor, hMC4R.

Sequence selective recognition of DNA by hairpin conjugates of a racemic seco-cyclopropaneindoline-2-benzofurancarboxamide and polyamides.

Conjugates of racemic seco-cyclopropaneindoline-2-benzofurancarboxamide (CI-Bf) and four diamides (ImIm 1, ImPy 2, PyIm 3, and PyPy 4, where Py is pyrrole, and Im is imidazole), linked by a gamma-aminobutyrate group were synthesized. In addition to alkylating at adenine-N3 positions within an A(5) sequence, the imidazole-containing compounds 1 and 2 were found to also alkylate purine-N3 positions within a sequence 3'-GGGGGGA(888)CTGCTC(894)-5'. A model for the binding of hairpin conjugates 1 and 2 with the 3'-GACT-5' sequence is proposed.

Novel furano analogues of duocarmycin C1 and C2: design, synthesis, and biological evaluation of seco-iso-cyclopropylfurano[2,3-e]indoline (seco-iso-CFI) and seco-cyclopropyltetrahydrofurano[2,3-f]quinoline (seco-CFQ) analogues.

The design, synthesis and biological evaluation of novel seco-iso-cyclopropylfurano[2,3-e]indoline (seco-iso-CFI) and the seco-cyclopropyltetrahydrofurano[2,3-f]quinoline (seco-CFQ) analogues of the duocarmycins are described. These novel analogues (4-7) were designed on the premise that the lone pair of electrons on the furano-oxygen atom could enter into conjugation with the isocyclopropylfurano[e]indolone (iso-CFI) alkylating moiety, formed from the loss of HCl in compounds 4-7. The seco-iso-CFI DNA alkylating pharmacophore was synthesized through a well precedented approach of 5-exo-trig aryl radical cyclization with a vinyl chloride.