Symptoms and impacts of familial chylomicronemia syndrome: a qualitative study of the patient experience.

BACKGROUND: Familial chylomicronemia syndrome (FCS) is a rare, hereditary, metabolic disorder. FCS causes high levels of triglycerides in the blood, which can lead to abdominal pain, xanthomas, and acute pancreatitis (AP). Volanesorsen, along with adherence to a very low-fat diet is used to reduce triglyceride levels in individuals with FCS. We aimed to understand the symptoms of FCS and their impact on health-related quality of life (HRQoL). METHODS: Interviews were conducted with individuals with genetically confirmed FCS in the UK and Spain, some of whom had been treated with volanesorsen. Interview guides were developed with input from a patient advocacy group to explore the symptoms, impacts and management of FCS. Interviews were conducted by telephone and were recorded and transcribed. Data were analyzed using thematic analysis and saturation was recorded. RESULTS: Seventeen interviews were conducted with individuals with FCS (aged 27-68 years), thirteen of whom were currently/previously treated with volanesorsen. Episodes of AP were the most impactful reported symptom, resulting in severe abdominal pain, nausea, vomiting, fever, bloating and appetite loss. Other symptoms and functional issues included abdominal pain, gastrointestinal symptoms, impaired cognitive function and fatigue. These had an impact on work, social activities, relationships and psychological wellbeing. These symptoms and impacts were illustrated in a conceptual model, including management strategies. The challenges of managing a low-fat diet and experience with volanesorsen were discussed. CONCLUSION: Individuals with FCS experience a range of interrelated symptoms and functional limitations which impact their broader HRQoL. Treatments which alleviate symptoms and reduce the incidence of AP episodes have the potential to improve the HRQoL of these individuals.

Qualitative development of the PROMIS Profile v1.0-Familial Chylomicronemia Syndrome (FCS) 28.

PURPOSE: Familial chylomicronemia syndrome (FCS) is a rare genetic disorder characterized by high triglyceride levels, significant disease burden, and negative impacts on health-related quality of life. This project aimed to create a PROMIS-based patient-reported outcome measure that represents valid and important concerns for patients with FCS. METHODS: We reviewed the literature and data from a previous qualitative study of FCS to identify key FCS symptoms and impacts, which were mapped to PROMIS domains to create a pool of eligible items. Candidate items were reduced per expert feedback and patients with FCS completed cognitive interviews to confirm content validity and measure content. RESULTS: Literature and qualitative data review identified ten key symptoms and 12 key impacts of FCS, including abdominal pain, fatigue, difficulty thinking, and worry about pancreatitis attacks. We identified 96 items primarily from PROMIS, supplemented with items from the Quality of Life in Neurological Disorders™ (Neuro-QoL™) and the Functional Assessment of Chronic Illness Therapy (FACIT) measurement systems. This pool was reduced to 32 candidate items, which were assessed via cognitive interviews with eight participants with FCS. Cognitive interview results and additional expert feedback led to the removal of four items and finalization of the PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28. CONCLUSIONS: The PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28 provides strong content validity for assessing quality of life among patients with FCS. The benefits of PROMIS, including norm-referenced mean values for each measure, will facilitate comparison of patients with FCS to other clinical populations.

Orphan drugs revisited: cost-effectiveness analysis of the addition of mifamurtide to the conventional treatment of osteosarcoma.

INTRODUCTION: Mepact(®) (mifamurtide) is the first drug approved for the treatment of high-grade resectable non-metastatic osteosarcoma in patients aged 2-30 in the last 20 years. It follows a randomized clinical trial showing a statistically-significant and clinically-relevant decrease in the risk of death without compromising safety. AIM: This study assessed the cost-effectiveness and budget impact of mifamurtide. METHODS: The economic evaluation was done on a hypothetical cohort of young patients under the age of 30 with high-grade, non-metastatic, resectable osteosarcoma. Standard chemotherapy without mifamurtide was used as comparator. A Markov model was adapted using Spanish costs and the results of the INT-0133 Phase III study. The analysis has been carried out from the perspective of the Spanish National Health Service, with a time horizon of up to 60 years in the base analysis. RESULTS: The observed greater efficacy of mifamurtide in the trial translates into a gain of 3.03 (undiscounted) and 1.33 (discounted) quality-adjusted life years at an additional cost of €102,000. The estimated budgetary impact of using mifamurtide in 10-100% of the potential population would cost €671,000 and €6.7 million respectively. CONCLUSION: The cost per quality-adjusted life years gained with mifamurtide in Spain is in the low band (<€100,000) of the iCERs obtained by other orphan drugs and would have a limited and affordable cost in Spain.

Selective inhibition of an apicoplastic aminoacyl-tRNA synthetase from Plasmodium falciparum.

The resistance of malaria parasites to available drugs continues to grow, and this makes the need for new antimalarial therapies pressing. Aminoacyl-tRNA synthetases (ARSs) are essential enzymes and well-established antibacterial targets and so constitute a promising set of targets for the development of new antimalarials. Despite their potential as drug targets, apicoplastic ARSs remain unexplored. We have characterized the lysylation system of Plasmodium falciparum, and designed, synthesized, and tested a set of inhibitors based on the structure of the natural substrate intermediate: lysyl-adenylate. Here we demonstrate that selective inhibition of apicoplastic ARSs is feasible and describe new compounds that that specifically inhibit Plasmodium apicoplastic lysyl-tRNA synthetase and show antimalarial activities in the micromolar range.

Chimeric tRNAs as tools to induce proteome damage and identify components of stress responses.

Misfolded proteins are caused by genomic mutations, aberrant splicing events, translation errors or environmental factors. The accumulation of misfolded proteins is a phenomenon connected to several human disorders, and is managed by stress responses specific to the cellular compartments being affected. In wild-type cells these mechanisms of stress response can be experimentally induced by expressing recombinant misfolded proteins or by incubating cells with large concentrations of amino acid analogues. Here, we report a novel approach for the induction of stress responses to protein aggregation. Our method is based on engineered transfer RNAs that can be expressed in cells or tissues, where they actively integrate in the translation machinery causing general proteome substitutions. This strategy allows for the introduction of mutations of increasing severity randomly in the proteome, without exposing cells to unnatural compounds. Here, we show that this approach can be used for the differential activation of the stress response in the Endoplasmic Reticulum (ER). As an example of the applications of this method, we have applied it to the identification of human microRNAs activated or repressed during unfolded protein stress.

Annexin A6-induced inhibition of cytoplasmic phospholipase A2 is linked to caveolin-1 export from the Golgi.

The molecular mechanisms regulating the exit of caveolin from the Golgi complex are not fully understood. Cholesterol and sphingolipid availability affects Golgi vesiculation events and involves the activity of cytoplasmic phospholipase A(2) (cPLA(2)). We recently demonstrated that high expression levels of annexin A6 (AnxA6) perturb the intracellular distribution of cellular cholesterol, thereby inhibiting caveolin export from the Golgi complex. In the present study we show that in Chinese hamster ovary cells overexpressing AnxA6, sequestration of cholesterol in late endosomes, leading to reduced amounts of cholesterol in the Golgi, inhibits cPLA(2) activity and its association with the Golgi complex. This correlates with the blockage of caveolin export from the Golgi in cells treated with methyl arachidonyl fluorophosphonate, a Ca(2+)-dependent cPLA(2) inhibitor. AnxA6-mediated down-regulation of cPLA(2) activity was overcome upon the addition of exogenous cholesterol or transfection with small interfering RNA targeting AnxA6. These findings indicate that AnxA6 interferes with caveolin transport through the inhibition of cPLA(2).

Annexin A6-induced alterations in cholesterol transport and caveolin export from the Golgi complex.

Annexin A6 (AnxA6) belongs to a family of Ca(2+)-dependent membrane-binding proteins and is involved in the regulation of endocytic and exocytic pathways. We previously demonstrated that AnxA6 regulates receptor-mediated endocytosis and lysosomal targeting of low-density lipoproteins and translocates to cholesterol-enriched late endosomes (LE). As cholesterol modulates the membrane binding and the cellular location of AnxA6, but also affects the intracellular distribution of caveolin, we investigated the localization and trafficking of caveolin in AnxA6-expressing cells. Here, we show that cells expressing high levels of AnxA6 are characterized by an accumulation of caveolin-1 (cav-1) in the Golgi complex. This is associated with a sequestration of cholesterol in the LE and lower levels of cholesterol in the Golgi and the plasma membrane, both likely contributing to retention of caveolin in the Golgi apparatus and a reduced number of caveolae at the cell surface. Further strengthening these findings, knock down of AnxA6 and the ectopic expression of the Niemann-Pick C1 protein in AnxA6-overexpressing cells restore the cellular distribution of cav-1 and cholesterol, respectively. In summary, this study demonstrates that elevated expression levels of AnxA6 perturb the intracellular distribution of cholesterol, which indirectly inhibits the exit of caveolin from the Golgi complex.

Inhibition of H-Ras and MAPK is compensated by PKC-dependent pathways in annexin A6 expressing cells.

High-density lipoprotein (HDL)-induced activation of the Ras/MAPK pathway can be mediated by protein kinase C (PKC)-dependent and independent pathways. Although both pathways co-exist in cells, we showed that binding of HDL to scavenger receptor BI (SR-BI) in CHO cells activates Ras and MAPK in a PKC-independent manner. We have recently identified that HDL-induced activation of Ras and Raf-1 is reduced in annexin A6 expressing CHO cells (CHOanx6). In the present study we demonstrate that despite the loss of Ras and Raf-1 activity, HDL induces MAPK phosphorylation in CHOanx6 cells. Since annexin A6 is a PKCalpha-binding protein we therefore investigated the possible involvement of PKC in HDL-induced Ras and MAPK activation in CHOanx6 cells. Taken together our findings demonstrate that HDL-induced H-Ras and MAPK activation is PKC-dependent in cells expressing annexin A6 to compensate for the loss of PKC-independent activation of H-Ras and MAPK.

Annexin A6 stimulates the membrane recruitment of p120GAP to modulate Ras and Raf-1 activity.

Annexin A6 is a calcium-dependent membrane-binding protein that interacts with signalling proteins, including the GTPase-activating protein p120GAP, one of the most important inactivators of Ras. Since we have demonstrated that annexin A6 inhibits EGF- and TPA-induced Ras signalling, we investigated whether modulation of Ras activity by annexin A6 was mediated via altered subcellular localization of p120GAP. First, we exploited our observation that high-density lipoproteins (HDL) can activate the Ras/MAP kinase pathway. Expression of annexin A6 caused a significant reduction in HDL-induced activation of Ras and Raf-1. Annexin A6 promoted membrane binding of p120GAP in vitro, and plasma membrane targeting of p120GAP in living cells, both in a Ca(2+)-dependent manner, which is consistent with annexin A6 promoting the Ca(2+)-dependent assembly of p120GAP-Ras at the plasma membrane. We then extended these studies to other cell types and stimuli. Expression of annexin A6 in A431 cells reduced, while RNAi-mediated suppression of annexin A6 in HeLa cells enhanced EGF-induced Ras and Erk activation. Importantly, the enhancement of Ras activation following RNAi-mediated reduction in p120GAP levels was more marked in annexin A6-expressing A431 cells than controls, indicating that the effect of annexin A6 on Ras was mediated via p120GAP. Finally, we demonstrated that annexin A6 promotes plasma membrane targeting of p120GAP in A431 cells in response to a variety of stimuli, resulting in colocalization with H-Ras. These findings demonstrate an important role for annexin A6 in regulating plasma membrane localization of p120GAP and hence Ras activity.