Collins Cheruiyot

Abstract Immune checkpoint blockade is effective for some patients with cancer, but most are refractory to current immunotherapies and new approaches are needed to overcome resistance 1,2 . The protein tyrosine phosphatases PTPN2 and PTPN1 are central regulators of inflammation, and their genetic deletion in either tumour cells or immune cells promotes anti-tumour immunity 3–6 . However, phosphatases are challenging drug targets; in particular, the active site has been considered undruggable. Here we present the discovery and characterization of ABBV-CLS-484 (AC484), a first-in-class, orally bioavailable, potent PTPN2 and PTPN1 active-site inhibitor. AC484 treatment in vitro amplifies the response to interferon and promotes the activation and function of several immune cell subsets. In mouse models of cancer resistant to PD-1 blockade, AC484 monotherapy generates potent anti-tumour immunity. We show that AC484 inflames the tumour microenvironment and promotes natural killer cell and CD8 + T cell function by enhancing JAK–STAT signalling and reducing T cell dysfunction. Inhibitors of PTPN2 and PTPN1 offer a promising new strategy for cancer immunotherapy and are currently being evaluated in patients with advanced solid tumours (ClinicalTrials.gov identifier NCT04777994 ). More broadly, our study shows that small-molecule inhibitors of key intracellular immune regulators can achieve efficacy comparable to or exceeding that of antibody-based immune checkpoint blockade in preclinical models. Finally, to our knowledge, AC484 represents the first active-site phosphatase inhibitor to enter clinical evaluation for cancer immunotherapy and may pave the way for additional therapeutics that target this important class of enzymes.

BACKGROUND: In Kenya, diarrheal disease is the second leading cause of death among children under five. The Government of Kenya launched a national plan to increase coverage of oral rehydration solution (ORS) and zinc by addressing demand and supply-side barriers. This study evaluates progress of ORS and zinc uptake in Kenya according to the national plan from 2011 to 2016. METHODS: In 2016, we conducted a nationally representative population-based household survey to estimate coverage of ORS and zinc for treatment of diarrhea cases among children under five. We also used ORS and zinc coverage data from the two most recent Kenya Demographic and Health Surveys in 2008/09 and 2014 to estimate annual changes in coverage rates during the program period. Based on these inputs, we used the Lives Saved Tool to estimate the number of diarrhea deaths averted between 2011 and 2016 due to increased use of ORS and zinc. RESULTS: The 2016 survey results showed that ORS coverage was 42% (95% confidence interval (CI) = 38%, 47%) and zinc coverage was 18% (95% CI = 15%, 23%). The estimated coverage for the combined use of ORS and zinc was 15% in 2016 (95% CI = 12%, 19%). Compared to 2011, an additional 3340 (sensitivity bounds = 2 670, 3 920) diarrhea deaths among children under five were averted due to increases in ORS and zinc coverage. CONCLUSIONS: Kenya was successful in catalyzing uptake of combined treatment with ORS and zinc, which rose from 0.8% in 2011 to 15% in 2016. Ongoing efforts are necessary to further build on these gains.

Exosomes are 30-100 nm extracellular vesicles secreted from late endosomes by various types of cells. Numerous studies have suggested that exosomes play significant roles in human immunodeficiency virus 1 (HIV-1) biogenesis. Proteomics coupled with exosome fractionation has been successfully used to identify various exosomal proteins and helped to uncover the interactions between exosomes and HIV-1. To inform the current progress in the intersection of exosome, proteomics, and HIV-1, this review is focused on: i) analyzing different exosome isolation, purification methods, and their implications in HIV-1 studies; ii) evaluating the roles of various proteomic techniques in defining exosomal contents; iii) discussing the research and clinical applications of proteomics and exosome in HIV-1 biology.

Proteomics is the large-scale analysis of proteins. Proteomic techniques, such as liquid chromatography tandem mass spectroscopy (LC-MS/MS), can characterize thousands of proteins at a time. These powerful techniques allow us to have a systemic understanding of cellular changes, especially when cells are subjected to various stimuli, such as infections, stresses, and specific test conditions. Even with recent developments, analyzing the exosomal proteome is time-consuming and often involves complex methodologies. In addition, the resultant large dataset often needs robust and streamlined analysis in order for researchers to perform further downstream studies. Here, we describe a SILAC-based protocol for characterizing the exosomal proteome when cells are infected with HIV-1. The method is based on simple isotope labeling, isolation of exosomes from differentially labeled cells, and mass spectrometry analysis. This is followed by detailed data mining and bioinformatics analysis of the proteomic hits. The resultant datasets and candidates are easy to understand and often offer a wealth of information that is useful for downstream analysis. This protocol is applicable to other subcellular compartments and a wide range of test conditions.