A study protocol to investigate if acipimox improves muscle function and sarcopenia: an open-label, uncontrolled, before-and-after experimental medicine feasibility study in community-dwelling older adults

INTRODUCTION

Sarcopenia is the age-associated loss of muscle mass and strength. Nicotinamide adenine dinucleotide (NAD) plays a central role in both mitochondrial function and cellular ageing processes implicated in sarcopenia. NAD concentrations are low in older people with sarcopenia, and increasing skeletal muscle NAD concentrations may offer a novel therapy for this condition. Acipimox is a licensed lipid-lowering agent known to act as an NAD precursor. This open-label, uncontrolled, before-and-after proof-of-concept experimental medicine study will test whether daily supplementation with acipimox improves skeletal muscle NAD concentrations.

METHODS AND ANALYSIS

Sixteen participants aged 65 and over with probable sarcopenia will receive acipimox 250 mg and aspirin 75 mg orally daily for 4 weeks, with the frequency of acipimox administration being dependent on renal function. Muscle biopsy of the vastus lateralis and MRI scanning of the lower leg will be performed at baseline before starting acipimox and after 3 weeks of treatment. Adverse events will be recorded for the duration of the trial. The primary outcome, analysed in a per-protocol population, is the change in skeletal muscle NAD concentration between baseline and follow-up. Secondary outcomes include changes in phosphocreatine recovery rate by 31P magnetic resonance spectroscopy, changes in physical performance and daily activity (handgrip strength, 4 m walk and 7-day accelerometry), changes in skeletal muscle mitochondrial respiratory function, changes in skeletal muscle mitochondrial DNA copy number and changes in NAD concentrations in whole blood as a putative biomarker for future participant selection.

ETHICS AND DISSEMINATION

The trial is approved by the UK Medicines and Healthcare Products Regulatory Agency (EuDRACT 2021-000993-28) and UK Health Research Authority and Northeast - Tyne and Wear South Research Ethics Committee (IRAS 293565). Results will be made available to participants, their families, patients with sarcopenia, the public, regional and national clinical teams, and the international scientific community.

PROTOCOL

Acipimox feasibility study Clinical Trial Protocol V.2 2/11/21.

TRIAL REGISTRATION NUMBER

The ISRCTN trial database (ISRCTN87404878).

Impaired cardiovascular function in primary biliary cirrhosis

Cardiovascular system dysregulation in the form of autonomic dysfunction is common at all stages of the disease process in the autoimmune liver disease primary biliary cirrhosis (PBC) and associates with the symptom of fatigue. The mechanisms underpinning autonomic dysfunction in PBC are, however, at present unclear. In this study we set out to explore, for the first time, cardiac structure and function in PBC using impedance cardiography (ICG) and magnetic resonance methodologies. ICG was assessed beat to beat in response to orthostasis (by head-up tilt) in age and sex case-matched high-fatigue and low-fatigue PBC groups (assessed by Fatigue Impact Scale), normal control subjects (n = 15 each group) and a liver disease control cohort (primary sclerosing cholangitis). Cardiac structure and bioenergetics were examined in 15 of the PBC subjects and 8 of the normal control subjects by magnetic resonance spectroscopy and cine imaging. Capacity of the left ventricle to respond to orthostasis [left ventricular ejection time (LVET)] was impaired in PBC compared with matched normal control subjects (P = 0.05). This was a PBC-specific phenomenon unrelated to fatigue status. PBC patients exhibited significantly lower cardiac muscle phosphocreatine-to-ATP ratio (PCr/ATP ratio; measure of cardiac bioenergetic integrity) compared with control subjects (P < 0.01). PCr/ATP <1.6 (indicative of increased risk of death in cardiomyopathy) was present in 6/15 (40%) PBC patients (0/8 control subjects; P < 0.05). Cardiac structure and function were similar in all measures of left ventricular morphology between control subjects and PBC. The close relationship between PCr/ATP and LVET seen in normal subjects (r(2) = 0.6; P < 0.05) was lost in PBC patients, a finding compatible with myocardial dysfunction. Significant correlation was seen between fatigue severity in PBC and fall in cardiac output on orthostasis (r(2) = 0.25; P = 0.005). Our findings suggest the presence of altered myocardial function in PBC. Autonomic "dysfunction" may, rather than being an abnormal process, represent a compensatory mechanism to increase cardiac return to mitigate these effects.

Genetic heterogeneity and minor CYP1B1 involvement in the molecular basis of primary congenital glaucoma in Gypsies

Primary congenital glaucoma (PCG) is a genetically heterogeneous disorder of autosomal recessive inheritance, with mutations in the cytochrome P450 1B1 (CYP1B1) gene detected in an average of approximately 50% of cases worldwide. The Roma/Gypsies are considered to be a rare example of a single founder CYP1B1 mutation, E387K (identified in the Slovak Roma), accounting for 100% of disease alleles. Contrary to this concept, unusual genetic heterogeneity was revealed in this study of 21 Gypsy PCG patients from Bulgaria and 715 controls from the general Gypsy population. In our small sample of affected subjects, we identified five different CYP1B1 mutations - four known (E229K, R368H, E387K and R390C) and one novel and potentially pathogenic (F445I), which together accounted for approximately 30% of disease alleles. E387K was rare in both the patient and the control group, indicating that its high frequency in the Slovak Roma is the product of local founder effect not representative of the overall molecular pattern of PCG in the Gypsy population. Data on other Mendelian disorders and on the population genetics of the Gypsies suggest that a true founder mutation is likely to exist and has remained undetected. Our analysis of another candidate gene, MYOC, and the GLC3B and GLC3C loci did not provide support for their involvement. The molecular basis of PCG in the Gypsies is thus unresolved, and diagnostic analyses should be extended beyond the E387K mutation.

High collagenolytic activity in spontaneously highly metastatic variants derived from a human pancreatic cancer cell line (SUIT-2) in nude mice

Cell lines with high metastatic capacity to the lung were established by sequential passage of a human pancreatic cancer cell line (SUIT-2) through the lung of a nude mouse, via the lateral tail vein and from a subcutaneous inoculum. Cells of the parental SUIT-2 and sublines S2-VPx (x-cycle selection from SUIT-2 cells, by Vein-Pulmonary metastasis-culture) and S2-CPx (x-cycle selection, by Cutis-Pulmonary metastasis-culture) were injected intravenously or subcutaneously into nude mice to produce experimental or spontaneous lung metastasis. The S2-VP10 cell line produced pulmonary metastases in 100% of the nude mice, when injected intravenously. It failed, however, to produce more lung colonies than its parent cell line, when injected subcutaneously. The S2-CP8 cell line produced extensive pulmonary metastases in 100% of the nude mice, when injected either intravenously or subcutaneously. This study indicates that the nude mouse provided a good model for in vivo selection of metastatic cells from SUIT-2 cells both experimentally and spontaneously, and that the SUIT-2, S2-VPx, and S2-CPx cell lines will be valuable in the study of human cancer metastasis. We previously reported high levels of ezrin expression in the S2-VP10 and S2-CP8 cell lines. Here we show that these cell lines exhibit a greater capacity to invade or attach to various extracellular matrix components than the parent SUIT-2 cells. The S2-CP8 cell lines also exhibit greater level of type-I and type-IV collagen-degrading activity than the parent SUIT-2 cell line and the S2-VP10 cell line, which shows similar collagen-degrading activity to the parent SUIT-2 cells. In RT-PCR studies, SUIT-2, S2-CP8 and S2-VP10 cell lines constitutively expressed many matrix metalloproteinases (MMP-1, MMP-2, MMP-3, MMP7, MMP-9, MMP-10 and MMP-14). These results suggest that some parameters that enhance adhesion and invasion are important to both experimental and spontaneous metastasis and the collagen degrading enzymes are predicted to play a key-role during spontaneous metastasis.

Determination and analysis of antigenic epitopes of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2) using synthetic peptides and computer modeling

Prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), produced essentially by the prostate gland, are 237-amino acid monomeric proteins, with 79% identity in primary structure. Twenty-five anti-PSA monoclonal antibodies (Mabs) were studied for binding to a large array of synthetic linear peptides selected from computer models of PSA and hK2, as well as to biotinylated peptides covering the entire PSA sequence. Sixteen of the Mabs were bound to linear peptides forming four independent binding regions (I-IV). Binding region I was localized to amino acid residues 1-13 (identical sequence for PSA and hK2), II (a and b) was localized to residues 53-64, III (a and b) was localized to residues 80-91 (= kallikrein loop), and IV was localized to residues 151-164. Mabs binding to regions I and IIa were reactive with free PSA, PSA-ACT complex, and with hK2; Mabs binding to regions IIb, IIIa, and IV were reactive with free PSA and PSA-ACT complex, but unreactive with hK2; Mabs binding to region IIIb detected free PSA only. All Mabs tested (n = 7) specific for free PSA reacted with kallikrein loop (binding region IIIb). The presence of Mabs interacting with binding region I did not inhibit the catalytic activity of PSA, whereas Mabs interacting with other binding regions inhibited the catalysis. Theoretical model structures of PSA, hK2, and the PSA-ACT complex were combined with the presented data to suggest an overall orientation of PSA with regard to ACT.

Tumor cell contamination of bone marrow harvest products: clinical consequences in a cohort of advanced-stage breast cancer patients undergoing high-dose chemotherapy

Patients undergoing high-dose chemotherapy (HDC) with autologous stem cell rescue (ASCR) may have tumor cells inadvertently infused if their stem cell product is tumor contaminated. We used an immunocytochemical (ICC) method to analyze 31 histologically negative bone marrow (BM) specimens taken from women with advanced-stage breast cancer at the time of BM harvest before HDC. All 31 patients were treated on one of three consecutive HDC protocols and received BM or BM and peripheral stem cells (PSC) as ASCR. Six of 26 evaluable patients had ICC-detectable contaminating tumor cells in their BM harvests. These 6 patients had a trend toward decreased overall survival compared with those patients without ICC-detectable tumor cells (17 months median versus 25+ months, p = 0.11, log rank test for those patients achieving complete response, CR, from HDC). The sites of relapse in the ICC-positive and ICC-negative groups were not notably different when analyzed for new sites versus previous sites of disease. Therefore, our retrospective analysis of a small cohort of patients suggests that the infusion of tumor cells in breast cancer patients undergoing HDC may confer a poor prognosis. Relapse patterns however suggest failure both in new sites and in sites of previous disease. Additional studies in expanded patient populations are needed to explore further the role of tumor cell infusion in ASCR and the possible clinical benefits of tumor cell removal procedures.