Lipid-Lowering Biotechnological Drugs: from Monoclonal Antibodies to Antisense Therapies—a Clinical Perspective

Purpose

While low density lipoprotein cholesterol (LDL-C) remains a key contributor of atherosclerotic cardiovascular disease (ASCVD), additional risk factors identified through epidemiological and genetic studies have ushered in a fertile era of drug discovery in lipid-lowering therapy. Unlike contemporary small molecule medications, many of the novel agents are biologics utilizing monoclonal antibody (mAb) or RNA interference (RNAi) technologies. This report aims to review the evidence to date, focusing on completed and ongoing clinical trials and how these new agents will impact clinical practice.

Methods

We review data from pertinent studies on lipid-lowering biologics in clinical use or have translated to human studies and are undergoing clinical trials.

Results

Several targets affecting lipid metabolism have been identified to be causally associated with ASCVD including proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3 (ANGPTL3), apolipoprotein C3 (APOC3), and lipoprotein (a) (Lp[a]). Biotechnological modalities that have been developed for these targets include mAb, small interfering RNA (siRNA), and anti-sense oligonucleotide (ASO) agents. Agents such as alirocumab and evolocumab have shown efficacy in risk reduction of ASCVD in cardiovascular outcome trials and have been incorporated into evidence-based practice guidelines. Other agents included in this review are in various stages of clinical trials and have shown significant efficacy in the reduction of lipid parameters.

Conclusion

The development of new biologics targeting lipid risk factors will provide clinicians additional tools to reduce the risk for ASCVD. Important factors to consider will be cost-effectiveness and improving methods to personalize treatments to risk factors.

     

Ethnic differences in response to lifestyle intervention for the prevention of type 2 diabetes in adults: A systematic review and meta-analysis

The risk of type 2 diabetes mellitus (T2DM) varies by ethnicity, but ethnic differences in response to diabetes prevention interventions remain unclear. This systematic review and meta-analysis assessed ethnic differences in the effects of lifestyle interventions on T2DM incidence, glycemic outcomes (fasting glucose, 2-h glucose, HbA_1c), anthropometric measures (weight, BMI, waist circumference), and lifestyle behaviors (physical activity, energy intake, energy from fat, fiber intake). MEDLINE, EMBASE, and other databases were searched (to June 15, 2020) for randomized and non-randomized controlled trials on lifestyle interventions (diet and/or physical activity) in adults at risk of T2DM. Ethnicity was categorized into European, South Asian, East and Southeast Asian, Middle Eastern, Latin American, and African groups. Forty-four studies were included in meta-analyses. Overall, lifestyle interventions resulted in significant improvement in T2DM incidence, glycemic outcomes, anthropometric measures, physical activity, and energy intake (all P < 0.01). Significant subgroup differences by ethnicity were found for 2-h glucose, weight, BMI, and waist circumference (all P < 0.05) but not for T2DM incidence, fasting glucose, HbA_1c, and physical activity (all P > 0.05). Few studies in non-European groups reported dietary intake. Lifestyle interventions in different ethnic groups may have similar effects in reducing incidence of T2DM although this needs to be confirmed in further studies.     

Intracardiac M-mode echocardiography for continuous left ventricular monitoring: method and potential application.

Because no accurate and readily applied method exists for continuous recording of left ventricular cavity dimensions and wall motion in man, we designed a catheter-mounted echocardiographic probe. The purpose of this report is to describe the instrumentation, technique, limitations, complications and preliminary observations employing the probe in humans. The echo transducer built into a cardiac allowed positioning in the right heart under fluoroscopy. The echo signals permitted continuous left ventricular cavity measurements at rest and during maneuvers. Our results suggest that intracardiac echo may be able to provide clear definition of motion patterns of the mitral valve and left ventricular walls. The ultrasonic catheter is an instrument that potentially offers a new technique for continuous monitoring of left ventricular size and motion.     

Deficiency of Src family kinases compromises the repopulating ability of hematopoietic stem cells

OBJECTIVE: Src family kinases (SFK) have been implicated in regulating growth factor and integrin-induced proliferation, migration, and gene expression in multiple cell types. However, little is known about the role of these kinases in the growth, homing, and engraftment potential of hematopoietic stem and progenitor cells. RESULTS: Here we show that loss of hematopoietic-specific SFKs Hck, Fgr, and Lyn results in increased number of Sca-1(+)Lin(-) cells in the bone marrow, which respond differentially to cytokine-induced growth in vitro and manifest a significant defect in the long-term repopulating potential in vivo. Interestingly, a significant increase in expression of adhesion molecules, known to coincide with the homing potential of wild-type bone marrow cells is also observed on the surface of SFK(-/-) cells, although, this increase did not affect the homing potential of more primitive Lin(-)Sca-1(+) SFK(-/-) cells. The stem cell-repopulating defect observed in mice transplanted with SFK(-/-) bone marrow cells is due to the loss of Lyn Src kinase, because deficiency of Lyn, but not Hck or Fgr, recapitulated the long-term stem cell defect observed in mice transplanted with SFK(-/-) bone marrow cells. CONCLUSIONS: Taken together, our results demonstrate an essential role for Lyn kinase in positively regulating the long-term and multilineage engraftment of stem cells, which is distinct from its role in mature B cells and myeloid cells.     

Peripherally inserted central venous catheters for treatment of cystic fibrosis

Patients who have cystic fibrosis (CF) are frequently hospitalized for long-term intravenous (IV) treatment. We evaluated clinical effectiveness of the Drum-Cartridge Catheter (Abbott Laboratories) for such patients. The catheter is placed peripherally under local anesthesia via an antecubital vein into the superior vena cava or right atrium. Patients who were more than 10 years of age and who were hospitalized for IV antibiotic therapy and/or IV hyperalimentation were studied. All but 2 patients had CF. Using an aseptic technique the catheters were inserted into the basilic or cephalic vein. Chest radiographs were used to confirm the final location of the catheter. Catheters were used to administer IV antibiotics, hyperalimentation, and lipids. There were 38 catheterizations in 23 patients; several patients had repeated insertions at later admissions. The success rate of insertion was 86% with 31 of the 38 insertions initially located either in the superior vena cava or right atrium. Mean duration of catheterization was 15.4 days (range 5-49 days). No major complications such as sepsis, catheter or clot embolism, pneumothorax, vascular perforation, or hemorrhage occurred in the patients who had DF. Complications that required displacement of catheter into the axillary vein (1 patient), and cracked catheter hub (1 patient). This study shows that the Drum-Cartridge Catheter can be used easily for IV therapy of patients who have CF for a long duration, repeatedly, and with no major complications.     

Detection of clonal platelet antibodies in immunologically-mediated thrombocytopenias: association with circulating clonal/oligoclonal B cells

Summary Aware that T and B cells in autoimmune thrombocytopenia are abnormal, including the existence of clonal B cell populations, we sought to characterize this clonal phenomenon in various immunological thrombocytopenias using platelet antibody light chain analysis, flow cytometry, Southern blot analysis, and PCR. Using a monoclonal antibody-antigen capture ELISA, we analysed sera from 21 of 26 patients with autoimmune, alloimmune. or drug-induced immunological thrombocytopenia for the light chain phenotypes of their platelet antibodies. Alloantibodies and drug-dependent antibodies from four and 14 patients, respectively, were found that expressed a predominant type of light chain, suggesting that these platelet-reactive antibodies were monoclonal or oligoclonal in nature. 14 of the 26 patients were available for light chain B cell phenotyping studies. Of these 14 patients, thrombocytopenia was due to autoimmunity in two, drug-induced immunity in four, and alloimmunity in eight. We detected clonal populations of B cells in all 14 patients by flow cytometry. Although six of these latter patients possessed platelet antibodies with clonal characteristics, light chain phenotypes of antibodies in five patients were opposite to those of their B cells. Eight of these patients were further examined for immunoglobulin gene rearrangement using Southern and/or polymerase chain reaction analysis. In all eight patients we detected clonal or oligoclonal B cell populations. Only two of these patients had malignancies (chronic lymphocytic leukaemia) that would be expected to have detectable clonal B cells, and thus the mechanism for clonal expansion in the other six patients did not appear to he related to an obvious neoplastic process. Prior to these studies, detection of clonal B cells in thrombocytopenic patients without known malignancies was limited to individuals with autoimmune thrombocytopenia, prompting the speculation that this particular autoimmune disorder arises from B cell dysregulation, rather than from expansion of specific autoantibody producing B cell clones. In contrast, the current studies provide evidence that clonal B cells are common to patients with any form of immunologically-mediated thrombocytopenia. Moreover, the majority of the platelet antibodies (86%) present in these disorders exhibited monoclonal characteristics in that there was an apparent restriction in light chain usage.     

Interference with Ca2+ release activated Ca2+ (CRAC) channel function delays T‐cell arrest in vivo

Entry of lymphocytes into secondary lymphoid organs (SLOs) involves intravascular arrest and intracellular calcium ion ([Ca²⁺]_i) elevation. TCR activation triggers increased [Ca²⁺]_i and can arrest T‐cell motility in vitro. However, the requirement for [Ca²⁺]_i elevation in arresting T cells in vivo has not been tested. Here, we have manipulated the Ca²⁺ release‐activated Ca²⁺ (CRAC) channel pathway required for [Ca²⁺]_i elevation in T cells through genetic deletion of stromal interaction molecule (STIM) 1 or by expression of a dominant‐negative ORAI1 channel subunit (ORAI1‐DN). Interestingly, the absence of CRAC did not interfere with homing of naïve CD4⁺ T cells to SLOs and only moderately reduced crawling speeds in vivo. T cells expressing ORAI1‐DN lacked TCR activation induced [Ca²⁺]_i elevation, yet arrested motility similar to control T cells in vitro. In contrast, antigen‐specific ORAI1‐DN T cells had a twofold delayed onset of arrest following injection of OVA peptide in vivo. CRAC channel function is not required for homing to SLOs, but enhances spatiotemporal coordination of TCR signaling and motility arrest.     

RNF43 is a tumour suppressor gene mutated in mucinous tumours of the ovary

Mucinous carcinomas represent a distinct morphological subtype which can arise from several organ sites, including the ovary, and their genetic characteristics are largely under‐described. Exome sequencing of 12 primary mucinous ovarian tumours identified RNF43 as the most frequently somatically mutated novel gene, secondary to KRAS and mutated at a frequency equal to that of TP53 and BRAF. Further screening of RNF43 in a larger cohort of ovarian tumours identified additional mutations, with a total frequency of 2/22 (9%) in mucinous ovarian borderline tumours and 6/29 (21%) in mucinous ovarian carcinomas. Seven mutations were predicted to truncate the protein and one missense mutation was predicted to be deleterious by in silico analysis. Six tumours had allelic imbalance at the RNF43 locus, with loss of the wild‐type allele. The mutation spectrum strongly suggests that RNF43 is an important tumour suppressor gene in mucinous ovarian tumours, similar to its reported role in mucinous pancreatic precancerous cysts. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.