The PTPN2/PTPN1 inhibitor ABBV-CLS-484 unleashes potent anti-tumour immunity.

Immune checkpoint blockade is effective for some patients with cancer, but most are refractory to current immunotherapies and new approaches are needed to overcome resistance1,2. 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 immunity3-6. 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.

Research priorities to support evidence-informed policies and advocacy for access to safe abortion care in sub-Saharan Africa.

A key obstacle to advocacy efforts to promote legal and policy reforms that ensure women's and girls' access to comprehensive abortion care (CAC) is the lack of relevant and timely evidence. This commentary outlines a research agenda-setting initiative that identified research priorities to support evidence-informed policy and advocacy for CAC access in sub-Saharan Africa (SSA). It involved three phases: 1) a landscape analysis; 2) research agenda co-creation with stakeholders, and 3) a validation exercise on research priorities. Overall, the priority evidence needs included 1) estimating the incidence and magnitude of unsafe abortion and related costs; 2) examining the role of abortion laws and policies in facilitating or inhibiting access to CAC; 3) developing and documenting successful approaches for addressing societal barriers to the provision of CAC, and fostering a more inclusive and liberal abortion environment, and 4) documenting practice-based evidence on the provision of legal abortion services as well as for advocating for CAC. Various stakeholders, including researchers, policymakers, civil society organizations, and funding agencies, will find the agenda useful as they engage, at different levels, for the full domestication and implementation of forward-looking commitments on access to CAC in SSA.

An evaluation of a national oral rehydration solution and zinc scale-up program in Kenya between 2011 and 2016.

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.

Loss of ADAR1 in tumours overcomes resistance to immune checkpoint blockade.

Most patients with cancer either do not respond to immune checkpoint blockade or develop resistance to it, often because of acquired mutations that impair antigen presentation. Here we show that loss of function of the RNA-editing enzyme ADAR1 in tumour cells profoundly sensitizes tumours to immunotherapy and overcomes resistance to checkpoint blockade. In the absence of ADAR1, A-to-I editing of interferon-inducible RNA species is reduced, leading to double-stranded RNA ligand sensing by PKR and MDA5; this results in growth inhibition and tumour inflammation, respectively. Loss of ADAR1 overcomes resistance to PD-1 checkpoint blockade caused by inactivation of antigen presentation by tumour cells. Thus, effective anti-tumour immunity is constrained by inhibitory checkpoints such as ADAR1 that limit the sensing of innate ligands. The induction of sufficient inflammation in tumours that are sensitized to interferon can bypass the therapeutic requirement for CD8+ T cell recognition of cancer cells and may provide a general strategy to overcome immunotherapy resistance.

Proteomic Analysis of Exosomes and Its Application in HIV-1 Infection.

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.

SILAC Based Proteomic Characterization of Exosomes from HIV-1 Infected Cells.

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.

Stem-loop binding protein is a multifaceted cellular regulator of HIV-1 replication.

A rare subset of HIV-1-infected individuals is able to maintain plasma viral load (VL) at low levels without antiretroviral treatment. Identifying the mechanisms underlying this atypical response to infection may lead to therapeutic advances for treating HIV-1. Here, we developed a proteomic analysis to compare peripheral blood cell proteomes in 20 HIV-1-infected individuals who maintained either high or low VL with the aim of identifying host factors that impact HIV-1 replication. We determined that the levels of multiple histone proteins were markedly decreased in cohorts of individuals with high VL. This reduction was correlated with lower levels of stem-loop binding protein (SLBP), which is known to control histone metabolism. Depletion of cellular SLBP increased promoter engagement with the chromatin structures of the host gene high mobility group protein A1 (HMGA1) and viral long terminal repeat (LTR), which led to higher levels of HIV-1 genomic integration and proviral transcription. Further, we determined that TNF-α regulates expression of SLBP and observed that plasma TNF-α levels in HIV-1-infected individuals correlated directly with VL levels and inversely with cellular SLBP levels. Our findings identify SLBP as a potentially important cellular regulator of HIV-1, thereby establishing a link between histone metabolism, inflammation, and HIV-1 infection.