Role of pyrimidine depletion in the mitochondrial cardiotoxicity of nucleoside analogue reverse transcriptase inhibitors

Primary Prevention of Cardiovascular Disease for People Living with Human Immunodeficiency Virus

People living with HIV (PLWH) have a risk of cardiovascular disease (CVD) that is 1.5 to 2 times higher than the general population owing to traditional risk factors, HIV-mediated factors like chronic inflammation and immune dysfunction, and exposure to antiretroviral therapy. Currently available CVD risk estimation calculators tend to underestimate risk in PLWH but can be useful when an individual's HIV history is considered. Improving modifiable risks is the primary intervention for reducing CVD risk in PLWH. Statin therapy is important for specific individuals, but attention should be given to drug interactions with antiretroviral agents used to treat HIV.

A Targeted Metabolomics-Based Assay Using Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Identifies Structural and Functional Cardiotoxicity Potential

Implementing screening assays that identify functional and structural cardiotoxicity earlier in the drug development pipeline has the potential to improve safety and decrease the cost and time required to bring new drugs to market. In this study, a metabolic biomarker-based assay was developed that predicts the cardiotoxicity potential of a drug based on changes in the metabolism and viability of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). Assay development and testing was conducted in 2 phases: (1) biomarker identification and (2) targeted assay development. In the first phase, metabolomic data from hiPSC-CM spent media following exposure to 66 drugs were used to identify biomarkers that identified both functional and structural cardiotoxicants. Four metabolites that represent different metabolic pathways (arachidonic acid, lactic acid, 2'-deoxycytidine, and thymidine) were identified as indicators of cardiotoxicity. In phase 2, a targeted, exposure-based biomarker assay was developed that measured these metabolites and hiPSC-CM viability across an 8-point concentration curve. Metabolite-specific predictive thresholds for identifying the cardiotoxicity potential of a drug were established and optimized for balanced accuracy or sensitivity. When predictive thresholds were optimized for balanced accuracy, the assay predicted the cardiotoxicity potential of 81 drugs with 86% balanced accuracy, 83% sensitivity, and 90% specificity. Alternatively, optimizing the thresholds for sensitivity yields a balanced accuracy of 85%, 90% sensitivity, and 79% specificity. This new hiPSC-CM-based assay provides a paradigm that can identify structural and functional cardiotoxic drugs that could be used in conjunction with other endpoints to provide a more comprehensive evaluation of a drug's cardiotoxicity potential.

WS. Characteristics, Prevention, and Management of Cardiovascular Disease in People Living With HIV: A Scientific Statement From the American Heart Association

As early and effective antiretroviral therapy has become more widespread, HIV has transitioned from a progressive, fatal disease to a chronic, manageable disease marked by elevated risk of chronic comorbid diseases, including cardiovascular diseases (CVDs). Rates of myocardial infarction, heart failure, stroke, and other CVD manifestations, including pulmonary hypertension and sudden cardiac death, are significantly higher for people living with HIV than for uninfected control subjects, even in the setting of HIV viral suppression with effective antiretroviral therapy. These elevated risks generally persist after demographic and clinical risk factors are accounted for and may be partly attributed to chronic inflammation and immune dysregulation. Data on long-term CVD outcomes in HIV are limited by the relatively recent epidemiological transition of HIV to a chronic disease. Therefore, our understanding of CVD pathogenesis, prevention, and treatment in HIV relies on large observational studies, randomized controlled trials of HIV therapies that are underpowered to detect CVD end points, and small interventional studies examining surrogate CVD end points. The purpose of this document is to provide a thorough review of the existing evidence on HIV-associated CVD, in particular atherosclerotic CVD (including myocardial infarction and stroke) and heart failure, as well as pragmatic recommendations on how to approach CVD prevention and treatment in HIV in the absence of large-scale randomized controlled trial data. This statement is intended for clinicians caring for people with HIV, individuals living with HIV, and clinical and translational researchers interested in HIV-associated CVD.

Mitochondrial DNA mutations in ageing and disease: implications for HIV?

Mitochondrial DNA (mtDNA) mutations cause neurological and multisystem disease. Somatic (acquired) mtDNA mutations are also associated with degenerative diseases and with normal human ageing. It is well established that certain nucleoside reverse transcriptase inhibitor (NRTI) antiretroviral drugs cause inhibition of the mtDNA polymerase, pol γ, leading to a reduction in mtDNA content (depletion). Given this effect of NRTI therapy on mtDNA replication, it is plausible that NRTI treatment may also lead to increased mtDNA mutations. Here we review recent evidence for an effect of HIV infection or NRTI therapy on mtDNA mutations, as well as discussing the methodological challenges in addressing this question. Finally, we discuss the possible implications for HIV-infected persons, with particular reference to ageing.

Nonclinical Safety Profile of BMS-986001, a Nucleoside Transcriptase Inhibitor for Combination Retroviral Therapy

Nucleoside reverse transcriptase inhibitors (NRTIs)/nucleotide reverse transcriptase inhibitors are key components of combination antiretroviral therapy for HIV infection. First-generation NRTIs are associated with mitochondrial toxicity in patients, mainly due to inhibition of human DNA polymerase γ (hDNA polγ) that manifests as adverse events such as lipodystrophy, lactic acidosis, myopathy, cardiomyopathy, or nephropathy in patients. In chronic nonclinical studies in rodents and nonrodents, eukaryotic (host) mitochondrial toxicity manifests as some drug-specific toxicities similar to human toxicity. BMS-986001, a novel thymidine analog with minimal hDNA polγ inhibition, has demonstrated antiretroviral activity in early clinical studies. The primary toxicity of BMS-986001 in rats and monkeys is bone marrow dyserythropoiesis with associated decreases in red blood cell mass. Additionally, at high doses, severe platelet reductions accompanied by cutaneous petechiae began during weeks 8 and 11 in 3 of 60 monkeys in chronic toxicity studies. In a 6-month study, platelet reductions required euthanasia of the 2 affected monkeys (300 mg/kg/d) at week 14, but with dose reduction (200 mg/kg/d) remaining monkeys had no platelet changes. One affected monkey (200 mg/kg/d) in a 9-month study completed dosing and its platelet counts recovered during a 1-month recovery. Formation of platelet-bound immunoglobulin in the presence of BMS-986001, together with rapid and complete platelet recovery in the absence of BMS-986001, suggested that platelet decreases in monkeys may be immune mediated. No findings indicative of mitochondrial toxicity were observed in rats or monkeys given BMS-986001, suggesting an improved safety profile compared to marketed NRTI or tenofovir disoproxil fumarate.

HIV treatment and associated mitochondrial pathology: review of 25 years of in vitro, animal, and human studies

Antiretroviral therapy has dramatically reduced mortality in human immunodeficiency virus (HIV) infection. In 1988, the suggestion that the first antiretroviral drug, zidovudine, was the potential cause of muscle pathology in HIV-infected persons resulted in structural and biochemical patient studies demonstrating acquired mitochondrial dysfunction. Assessment of subsequent nucleoside analog reverse transcriptase inhibitor (NRTI) antiretroviral drugs has indicated that mitochondria are a common target of NRTI toxicity in multiple tissues, leading to a wide variety of pathology ranging from lipodystrophy to neuropathy. Overwhelmingly, these complications have emerged during post-licensing human studies. Subsequent animal and in vitro studies have then elucidated the potential pathological mechanisms, suggesting that NRTI-associated mitochondrial toxicity arises principally from inhibition of the sole mitochondrial DNA (mtDNA) polymerase gamma, leading to a reduction in mtDNA content (depletion). Millions of patients have been treated with mitochondrially toxic NRTIs and these drugs remain the backbone of antiretroviral rollout in much of sub-Saharan Africa. Here we describe the 25-year history of antiretroviral associated mitochondrial pathology and critically review the strength of evidence linking clinical, histopathological, and molecular data. We discuss recently described novel mechanisms of NRTI-associated mitochondrial damage and whether or not recently licensed NRTIs may be considered free from mitochondrial toxicity.