👤 Amanda J Hooper

Introduction: Pathogenic heterozygous melanocortin-4 receptor (MC4R) variants are the most common cause of monogenic obesity, affecting central satiety and appetite regulatory areas of the brain. Case Presentations: We report a pedigree with a pathogenic MC4R variant (c.380C>T, p.Ser127Leu). In the proband with obesity (BMI 35 kg/m2) and severe insulin resistance, use of combination of semaglutide and naltrexone-bupropion was successful in reducing insulin requirements and weight. His adult monozygotic twin daughters both had childhood-onset obesity; however, weight trajectories differed. Twin 1 had a peak BMI of 29.1 kg/m2, which decreased to 19.7 kg/m2 with intensive exercise and diet control without weight-lowering medication. Twin 2 had a sedentary lifestyle and epilepsy and had a peak BMI of 30.1 kg/m2; she responded well to naltrexone-bupropion and BMI decreased to 26 kg/m2. Conclusion: The manifestation of obesity, even in cases of monogenic obesity, can vary significantly due to the influence of environmental and lifestyle factors.

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Lipoprotein(a) [Lp(a)] is an independent, inherited risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis. Lp(a) is an LDL-like particle containing apoB-100 and apo(a). Lifestyle changes and statin therapy lower LDL-cholesterol and apoB, but do not reduce Lp(a), whereas PCSK9 inhibitors exert a modest effect. There are currently no approved Lp(a)-lowering drugs, although several are at various phases of clinical development. We discuss the role of Lp(a) as a therapeutic target, describe the development, pharmacodynamics, pharmacokinetics, and metabolism of zerlasiran, a small interfering RNA (siRNA) targeting Lp(a), and report the findings of recent clinical trials. The GalNAc-conjugated siRNA zerlasiran reduces Lp(a) by targeting hepatic apo(a) synthesis and subsequent assembly of Lp(a), with comparable efficacy to other Lp(a)-lowering therapies in phase II development. Its long half-life, infrequent dosing, and potentially lower cost, together with its favorable safety and tolerability profile, make zerlasiran a promising candidate. However, long-term studies are needed to assess its impact on major adverse cardiovascular events and safety in diverse patient populations, and across different clinical settings. The phase III cardiovascular outcome study has not commenced. Show less

Lipoprotein(a) [Lp(a)] is an LDL-like particle, which is synthesized and assembled in the liver, and whose plasma levels are strongly associated with, and considered to be causative of, atherosclerotic cardiovascular disease (ASCVD). Several promising pharmacological therapies that directly target Lp(a) are under development. We discuss the role of Lp(a) in ASCVD, describe the pharmacodynamics, pharmacokinetics, and metabolism of muvalaplin, an oral Lp(a) inhibitor, as well as reporting on the findings of the phase II KRAKEN trial in adults at high cardiovascular risk with elevated Lp(a). Muvalaplin is the first oral small molecule inhibitor of Lp(a) formation for the treatment of elevated Lp(a). In KRAKEN, muvalaplin significantly reduced Lp(a) levels in high-risk patients by up to 70% and 85.5% by traditional and novel isoform-insensitive intact assays, respectively. Safety and tolerability studies reported to date are promising, with minimal effect on plasminogen activity that was independent of dose. In terms of patient convenience and adherence, the oral dosing of muvalaplin may confer practical advantages over injectable Lp(a)-lowering therapies. The results of the MOVE-Lp(a) phase III trial, which is evaluating the effect of muvalaplin on cardiovascular outcomes in high-risk patients with elevated Lp(a), are eagerly awaited. Show less

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, by preventing the degradation of LDL receptors, either through interference in the binding of PCSK9 to LDL receptors or through silencing of PCSK9 at a molecular level, have revolutionized lipid-lowering treatment and offer the opportunity to further improve clinical outcomes for patients with hypercholesterolemia. We discuss the role of PCSK9 as a therapeutic target for hypercholesterolemia, describe the pharmacodynamics, pharmacokinetics, and metabolism of recaticimab, and report the recent clinical trials with this 'humanized' IgG1 monoclonal antibody (mAb) against PCSK9. Recaticimab has a high affinity for PCSK9 that confers a prolonged duration of action. Recaticimab durably decreases LDL-cholesterol, non-HDL-cholesterol and apoB, but can also lower Lp(a). Recaticimab may offer advantages over current mAbs in clinical use in terms of its long half-life, dosing interval of up to 12 weeks, and potentially a lower cost; however, long-term concerns regarding immunogenicity remain. Longer-term studies in a variety of more diverse patient cohorts will be needed to further evaluate the efficacy, safety, and durability of recaticimab and to ascertain the optimal dosing schedule for cardiovascular outcome studies. Show less

Although low-density lipoprotein cholesterol (LDL-C) is established as the primary cardiovascular disease (CVD) risk factor, some individuals with LDL-C within desirable limits still develop coronary artery disease (CAD). Lipoprotein(a) (Lp(a)) has emerged as a genetically determined independent risk factor for CVD. This study aims to investigate Lp(a) by determining its association with coronary artery stenosis severity, identifying its ethnic-specific genetic determinants and assessing its relationship with an energy-dense dietary pattern. The PUTRA-CV study is a 3-year, multicentre, case-control observational study involving adult patients who have undergone coronary angiography. The primary outcome is the association between Lp(a) levels and the severity of angiographic CAD (assessed by Gensini or Syntax score). Secondary outcomes include the frequencies of Lp(a)-associated single nucleotide polymorphisms (SNPs) (rs10455872 and rs3798220) and the association between dietary patterns and Lp(a) levels. Lp(a) will be measured using a particle-enhanced immunoturbidimetric method, and SNPs will be genotyped using high-resolution melting. Dietary intake will be assessed using a validated semiquantitative food frequency questionnaire. Data will be analysed using SPSS. Descriptive statistics will be used to summarise population characteristics. Bivariate analyses will use chi-square (χ2), independent t-tests or Mann-Whitney U tests as appropriate. The independent association between Lp(a) and coronary artery stenosis severity will be determined using multivariable logistic regression, adjusting for confounders. Empirically driven dietary patterns will be derived using reduced rank regression, and their association with Lp(a) will be assessed. For genetic analysis, allele frequencies of the Ethical approval has been obtained from the ethics committees of the Ministry of Health Malaysia (NMRR ID-24-00877-2ID-IIR), Universiti Putra Malaysia (JKEUPM-2024-246), Universiti Teknologi MARA (REC/07/2024-OT/FB/2) and Universiti Malaya Medical Centre (MREC ID NO: 2 02 453-13692). The findings will be disseminated via peer-reviewed journals and conferences. Show less

Apolipoprotein (apo)C-III, a key regulator of plasma triglyceride (TG) levels, is a prime candidate for the treatment of hypertriglyceridemia (HTG), prevention of acute pancreatitis, and reduction of future atherosclerotic cardiovascular disease (ASCVD) events. We discuss the role of apoC-III as a therapeutic target for HTG, describe the pharmacodynamics, pharmacokinetics, and metabolism of olezarsen, as well as report on the findings of recent clinical trials with this liver-directed Olezarsen, a GalNac-conjugated ASO targeting apoC-III, can reduce TG levels by ~ 50% in patients with extreme HTG due to familial chylomicronemia syndrome, as well as in patients with moderate HTG. Attention is now focused on whether olezarsen reduces ASCVD risk in patients with moderate and severe HTG. While olezarsen does cause elevations in liver enzymes, these changes are not clinically meaningful, and are not associated with thrombocytopenia, an issue with its predecessor, volanesorsen. The need for 4-weekly administration puts olezarsen at a disadvantage to competing injectables. Results from the CORE, CORE2, and ESSENCE phase III clinical trials in patients with severe HTG, expected in the second half of 2025, will help determine the requirement for a larger cardiovascular outcomes trial. Show less

Tumor regression following immune checkpoint blockade (ICB) is often associated with immune-related adverse events (irAEs), marked by inflammation in non-cancerous tissues. This study was undertaken to investigate the functional relationship between anti-tumor and anti-self immunity, to facilitate irAE management while promoting anti-tumor immunity. Multiple biopsies from tumor and inflamed tissues were collected from a patient with melanoma experiencing both tumor regression and irAEs on ICB, who underwent rapid autopsy. Immune cells infiltrating melanoma lesions and inflamed normal tissues were subjected to gene expression profiling with multiplex qRT-PCR for 122 candidate genes. Subsequently, immunohistochemistry was conducted to assess the expression of 14 candidate markers of immune cell subsets and checkpoints. TCR-beta sequencing was used to explore T cell clonal repertoires across specimens. While genes involved in MHC I/II antigen presentation, IFN signaling, innate immunity and immunosuppression were abundantly expressed across specimens, irAE tissues over-expressed certain genes associated with immunosuppression (CSF1R, IL10RA, IL27/EBI3, FOXP3, KLRG1, SOCS1, TGFB1), including those in the COX-2/PGE2 pathway (IL1B, PTGER1/EP1 and PTGER4/EP4). Immunohistochemistry revealed similar proportions of immunosuppressive cell subsets and checkpoint molecules across samples. TCRseq did not indicate common TCR repertoires across tumor and inflammation sites, arguing against shared antigen recognition between anti-tumor and anti-self immunity in this patient. This comprehensive study of a single patient with melanoma experiencing both tumor regression and irAEs on ICB explores the immune landscape across these tissues, revealing similarities between anti-tumor and anti-self immunity. Further, it highlights expression of the COX-2/PGE2 pathway, which is known to be immunosuppressive and potentially mediates ICB resistance. Ongoing clinical trials of COX-2/PGE2 pathway inhibitors targeting the major COX-2 inducer IL-1B, COX-2 itself, or the PGE2 receptors EP2 and EP4 present new opportunities to promote anti-tumor activity, but may also have the potential to enhance the severity of ICB-induced irAEs. Show less

One genetic cause of markedly low plasma concentrations of apolipoprotein (apo) B and low density lipoprotein (LDL)-cholesterol is familial hypobetalipoproteinemia. We aimed to determine the molecular basis for the marked hypocholesterolemia consistent with heterozygous familial hypobetalipoproteinemia in a black female subject of Xhosa lineage. Coding regions of APOB, MTTP, PCSK9,ANGPTL3, SAR1B and APOC3 were sequenced, and APOE was genotyped. COS-7 cells were transfected with plasmids containing apoB variants. Western blotting was used to detect cellular and secreted apoB, and co-immunoprecipitation performed to assess binding with the microsomal triglyceride transfer protein (MTP). Sequence analysis of the APOB gene revealed her to be heterozygous for two novel variants, c.751G>A (A224T) and c.2854G>C (V925L). She was also homozygous for the APOEε2 allele, and did not carry a PCSK9 loss-of-function mutation. Although Ala(224) is within the postulated MTP binding region in apoB, it is not conserved among mammalian species. Subsequent genotyping showed that Ala224Thr is found in a southern African population (n=654) with an allele frequency of 1.15% and is not associated with plasma lipid levels. Val(925), like Ala(224), is within the N-terminal 1000 amino acids required for lipoprotein assembly, but was not found in the population screen. However, in vitro studies showed that apoB V925L did not affect apoB48 production or secretion nor have a deleterious effect on MTP interaction with apoB. Taken together, this suggests that the hypocholesterolemia in our case may be a result of being homozygous for APOEε2 with a low baseline cholesterol. Show less

Energy depletion has been highlighted as an important contributor to the pathology of hypertrophic cardiomyopathy (HCM), a common inherited cardiac disease. Pharmacological reversal of energy depletion appears an attractive approach and the use of perhexiline has been proposed as it is thought to shift myocardial metabolism from fatty acid to glucose utilisation, increasing ATP production and myocardial efficiency. We used the Mybpc3-targeted knock-in mouse model of HCM to investigate changes in the cardiac metabolome following perhexiline treatment. Echocardiography indicated that perhexiline induced partial improvement of some, but not all hypertrophic parameters after six weeks. Non-targeted metabolomics, applying ultra-high performance liquid chromatography-mass spectrometry, described a phenotypic modification of the cardiac metabolome with 272 unique metabolites showing a statistically significant change (p < 0.05). Changes in fatty acids and acyl carnitines indicate altered fatty acid transport into mitochondria, implying reduction in fatty acid beta-oxidation. Increased glucose utilisation is indirectly implied through changes in the glycolytic, glycerol, pentose phosphate, tricarboxylic acid and pantothenate pathways. Depleted reduced glutathione and increased production of NADPH suggest reduction in oxidative stress. These data delineate the metabolic changes occurring during improvement of the HCM phenotype and indicate the requirements for further targeted interventions. Show less

Hypertriglyceridaemia is a common biochemical abnormality that can be due to primary causes or, more commonly, secondary causes. Moderate hypertriglyceridaemia is a risk factor for cardiovascular disease and can develop into severe hypertriglyceridaemia which is a risk factor for acute pancreatitis. Familial chylomicronaemia is a rare autosomal recessive disorder, usually diagnosed in childhood and is characterized by marked hypertriglyceridaemia and biochemical deficiency of lipoprotein lipase (LPL), apolipoprotein (apo) C-II, homozygous (or compound heterozygous) gene mutations in LPL or more rarely, APOC2. Recently, loss-of-function mutations in the APOA5 gene have been reported in patients with severe hypertriglyceridaemia in whom LPL or APOC2 mutations were not found. We describe the clinical features and genetic analysis of three patients with severe hypertriglyceridaemia including novel mutations LPL c.464T>C (p.Leu155Pro) and APOA5 c.823C>T (p.Gln275*). Show less

Carcinoma-associated fibroblasts (CAFs) can promote the progression of tumours in many ways. They can remodel the extracellular matrix to generate an environment that enables the invasion of cancer cells. We hypothesised that compounds that prevent matrix remodelling by CAFs would block their ability to promote carcinoma cell invasion. We designed a screen for compounds that interfere with CAF-promoted matrix remodelling. Hits from this screen were investigated in organotypic invasion models of squamous cell carcinoma (SCC). We find that lovastatin and simvastatin reduce matrix remodelling by fibroblasts and thereby reduce SCC invasion. This class of compounds exert their effects partly through disrupting the function of Rab proteins, and we show a new role for Rab21 in promoting cancer cell invasion promoted by CAFs. Rab21 is required for CAFs to promote the invasion of cancer cells. It enables the accumulation of integrin alpha5 at the plasma membrane and subsequent force-mediated matrix remodelling. Show less

In the presence of a Wnt signal beta-catenin is spared from proteasomal degradation through a complex mechanism involving GSK3beta, resulting in the transcription of Wnt target genes. In this study we have explored whether GSK3alpha, a related isoform, can also regulate nuclear beta-catenin levels and whether this and the tau-directed kinase activity of GSK3alpha are modulated by Wnt. GSK3alpha or GSK3beta and their substrates, beta-catenin and tau, were transiently expressed in mammalian cells. Immunoblotting revealed that GSK3alpha reduces nuclear levels of beta-catenin, whilst reporter gene assays demonstrated that GSK3alpha inhibits beta-catenin-directed Tcf/Lef-dependent transcription. Moreover, activation of the Wnt pathway was found to attenuate both the beta-catenin- and the tau-directed kinase activities of GSK3alpha and GSK3beta. By immunoprecipitation we also found that axin-1, the beta-catenin destruction complex scaffold protein, binds GSK3alpha. In the light of these findings GSK3alpha warrants further investigation regarding its involvement in Wnt signalling and tauopathies such as Alzheimer's disease. Show less