Triethysilyl Enol Ethers in the Synthesis of Carbapenem Precursors.

A diastereoselective process for the formation of intermediates suitable for the preparation of C1 substituted carbapenems was developed. The process is readily scalable and does not involve organometallics or strong bases such as LDA.

Loss of Corneal Nerves and Corneal Haze in Patients with Fuchs' Endothelial Corneal Dystrophy with the Transcription Factor 4 Gene Trinucleotide Repeat Expansion.

Objective: Seventy percent of Fuchs' endothelial corneal dystrophy (FECD) cases are caused by an intronic trinucleotide repeat expansion in the transcription factor 4 gene (TCF4). The objective of this study was to characterize the corneal subbasal nerve plexus and corneal haze in patients with FECD with (RE+) and without the trinucleotide repeat expansion (RE-) and to assess the correlation of these parameters with disease severity. Design: Cross-sectional, single-center study. Participants: Fifty-two eyes of 29 subjects with a modified Krachmer grade of FECD severity from 1 to 6 were included in the study. Fifteen of the 29 subjects carried an expanded TCF4 allele length of ≥ 40 cytosine-thymine-guanine repeats (RE+). Main Outcomes Measures: In vivo confocal microscopy assessments of corneal nerve fiber length (CNFL), corneal nerve branch density, corneal nerve fiber density (CNFD), and anterior corneal stromal backscatter (haze); Scheimpflug tomography densitometry measurements of haze in anterior, central, and posterior corneal layers. Results: Using confocal microscopy, we detected a negative correlation between FECD severity and both CNFL and CNFD in the eyes of RE+ subjects (Spearman ρ = -0.45, P = 0.029 and ρ = -0.62, P = 0.0015, respectively) but not in the eyes of RE- subjects. Additionally, CNFD negatively correlated with the repeat length of the expanded allele in the RE+ subjects (Spearman ρ = -0.42, P = 0.038). We found a positive correlation between anterior stromal backscatter and severity in both the RE+ and RE- groups (ρ = 0.60, P = 0.0023 and ρ = 0.44, P = 0.024, respectively). The anterior, central, and posterior Scheimpflug densitometry measurements also positively correlated with severity in both the RE+ and RE- groups (P = 5.5 × 10-5, 2.5 × 10-4, and 2.9 × 10-4, respectively, after adjusting for the expansion status in a pooled analysis. However, for patients with severe FECD (Krachmer grades 5 and 6), the posterior densitometry measurements were higher in the RE+ group than in the RE- group (P < 0.05). Conclusions: Loss of corneal nerves in FECD supports the classification of the TCF4 trinucleotide repeat expansion disorder as a neurodegenerative disease. Haze in the anterior, central, and posterior cornea correlate with severity, irrespective of the genotype. Quantitative assessments of corneal nerves and corneal haze may be useful to gauge and monitor FECD disease severity in RE+ patients.

Predictors of Early Onset Glaucoma.

Purpose/Relevance: To determine the influence of hypertension (HTN), type 2 diabetes (DM2), migraine, and obstructive sleep apnea (OSA) on the onset of primary open-angle glaucoma (POAG) to enhance predictive accuracy. Methods: In this cross-sectional study, data for 389 eligible patients with POAG were collected through medical records review and phone surveys. All data were assessed collectively using stepwise multiple regression analysis to determine the relative contribution to age at POAG diagnosis. We used the following groups, based on age at diagnosis, HTN for patients with or without DM2 (model 1), HTN for patients with DM2 (model 2), DM2 for patients with or without HTN (model 3), and DM2 for patients with HTN (model 4). Results: In model 1, age at HTN diagnosis was associated with age at POAG diagnosis (ß = 0.14; 95% CI, 0.01-0.26, p = 0.04). In model 2, age at HTN diagnosis was not associated with age at POAG diagnosis (p > 0.05). In model 3, age at DM2 diagnosis was associated with age at POAG diagnosis (ß = 0.37; 95% CI 0.16-0.58, p = 0.001). In model 4, age at DM2 diagnosis was associated with age at POAG diagnosis (ß = 0.40; 95% CI 0.00-0.15, p = 0.003). Asian race/ethnicity was associated with early onset of POAG in model 3 (ß = -6.44; 95% CI -12.34-0.54, p = 0.033). OSA and migraine did not influence the onset of POAG. Conclusion: Our study found that the diagnosis of DM2 and HTN at an earlier age is associated with the early onset of POAG.

PCA062, a P-cadherin Targeting Antibody-Drug Conjugate, Displays Potent Antitumor Activity Against P-cadherin-expressing Malignancies.

The cell surface glycoprotein P-cadherin is highly expressed in a number of malignancies, including those arising in the epithelium of the bladder, breast, esophagus, lung, and upper aerodigestive system. PCA062 is a P-cadherin specific antibody-drug conjugate that utilizes the clinically validated SMCC-DM1 linker payload to mediate potent cytotoxicity in cell lines expressing high levels of P-cadherin in vitro, while displaying no specific activity in P-cadherin-negative cell lines. High cell surface P-cadherin is necessary, but not sufficient, to mediate PCA062 cytotoxicity. In vivo, PCA062 demonstrated high serum stability and a potent ability to induce mitotic arrest. In addition, PCA062 was efficacious in clinically relevant models of P-cadherin-expressing cancers, including breast, esophageal, and head and neck. Preclinical non-human primate toxicology studies demonstrated a favorable safety profile that supports clinical development. Genome-wide CRISPR screens reveal that expression of the multidrug-resistant gene ABCC1 and the lysosomal transporter SLC46A3 differentially impact tumor cell sensitivity to PCA062. The preclinical data presented here suggest that PCA062 may have clinical value for treating patients with multiple cancer types including basal-like breast cancer.

SHP2 blockade enhances anti-tumor immunity via tumor cell intrinsic and extrinsic mechanisms.

SHP2 is a ubiquitous tyrosine phosphatase involved in regulating both tumor and immune cell signaling. In this study, we discovered a novel immune modulatory function of SHP2. Targeting this protein with allosteric SHP2 inhibitors promoted anti-tumor immunity, including enhancing T cell cytotoxic function and immune-mediated tumor regression. Knockout of SHP2 using CRISPR/Cas9 gene editing showed that targeting SHP2 in cancer cells contributes to this immune response. Inhibition of SHP2 activity augmented tumor intrinsic IFNγ signaling resulting in enhanced chemoattractant cytokine release and cytotoxic T cell recruitment, as well as increased expression of MHC Class I and PD-L1 on the cancer cell surface. Furthermore, SHP2 inhibition diminished the differentiation and inhibitory function of immune suppressive myeloid cells in the tumor microenvironment. SHP2 inhibition enhanced responses to anti-PD-1 blockade in syngeneic mouse models. Overall, our study reveals novel functions of SHP2 in tumor immunity and proposes that targeting SHP2 is a promising strategy for cancer immunotherapy.

Distinct Transcriptional Programming Drive Response to MAPK Inhibition in BRAF V600-Mutant Melanoma Patient-Derived Xenografts.

Inhibitors targeting BRAF and its downstream kinase MEK produce robust response in patients with advanced BRAF V600-mutant melanoma. However, the duration and depth of response vary significantly between patients; therefore, predicting response a priori remains a significant challenge. Here, we utilized the Novartis collection of patient-derived xenografts to characterize transcriptional alterations elicited by BRAF and MEK inhibitors in vivo, in an effort to identify mechanisms governing differential response to MAPK inhibition. We show that the expression of an MITF-high, "epithelial-like" transcriptional program is associated with reduced sensitivity and adaptive response to BRAF and MEK inhibitor treatment. On the other hand, xenograft models that express an MAPK-driven "mesenchymal-like" transcriptional program are preferentially sensitive to MAPK inhibition. These gene-expression programs are somewhat similar to the MITF-high and -low phenotypes described in cancer cell lines, but demonstrate an inverse relationship with drug response. This suggests a discrepancy between in vitro and in vivo experimental systems that warrants future investigations. Finally, BRAF V600-mutant melanoma relies on either MAPK or alternative pathways for survival under BRAF and MEK inhibition in vivo, which in turn predicts their response to further pathway suppression using a combination of BRAF, MEK, and ERK inhibitors. Our findings highlight the intertumor heterogeneity in BRAF V600-mutant melanoma, and the need for precision medicine strategies to target this aggressive cancer.

Chemical crosslinking and mass spectrometric identification of interaction sites within soluble aggregate of protein therapeutics.

Protein aggregation presents a major challenge to bioengineering. In the present study, chemical crosslinking and mass spectrometry are employed to probe the interaction amongst soluble oligomer formed by Fc molecule of monoclonal antibody. Aggregation was induced by thermal stress at 42°C for 6h under physiological pH. Contacting residues on adjacent molecules were captured with bifunctional crosslinker BS3, followed by mass spectrometric identification of the crosslinked sites. The approach provides site-specific information regarding the binding interface that would have broad application in the field.

Neutral loss of isocyanic acid in peptide CID spectra: a novel diagnostic marker for mass spectrometric identification of protein citrullination.

Protein citrullination is emerging as an important signaling mechanism that modulates a variety of biological processes. This protein modification constitutes only a 1 Da mass shift, and can be readily confused with other common protein modifications that yield an identical mass shift. In an attempt to develop a robust methodology for detection of protein citrullination sites, we analyzed synthetic citrulline-containing peptides by electrospray ionization tandem mass spectrometry. Collision-induced dissociation (CID) spectra revealed abundant neutral loss of 43 Da from citrullinated peptide precursor ions, which was reconciled by elimination of the HNCO moiety (isocyanic acid) from the citrulline ureido group. The elimination occurs readily in multiple charge states of precursor ions and also in b and y ions. HNCO loss in CID spectra provides a novel diagnostic marker for citrullination, and its utility was demonstrated by the discovery of Arg197 as the specific site of citrullination on nucleophosmin upon peptidylarginine deiminase 4 treatment.