Median Plasma Research Articles

A phase 1/2, open-label, parallel group study to evaluate the safety and pharmacokinetics of DARE-HRT1 (80 μg estradiol/4 mg progesterone and 160 μg estradiol/8 mg progesterone intravaginal rings) over 12 weeks in healthy postmenopausal women.

Primary objectives were to evaluate the safety and systemic pharmacokinetics (PK) of DARE-HRT1, an intravaginal ring (IVR), which releases 17β2-Estradiol (E2) with progesterone (P4) for 28 days in healthy postmenopausal women. This was a randomized, open-label, 2-arm, parallel group study in 21 healthy postmenopausal women with an intact uterus. Women were randomized (1:1) to either DARE-HRT1 IVR1 (E2 80 μg/d with P4 4 mg/d) or DARE-HRT1 IVR2 (E2 160 μg/d with P4 8 mg/d). They used the IVR for three 28-day cycles, inserting a new IVR monthly. Safety was measured by treatment emergent adverse events and changes in systemic laboratories and the endometrial bilayer width. Baseline adjusted plasma PK of E2, P4, and estrone (E1) was described. Both DARE-HRT1 IVR were safe. All treatment emergent adverse events were mild or moderate and were distributed similarly among IVR1 versus IVR2 users. Month 3 median maximum plasma (Cmax) P4 concentrations were 2.81 and 3.51 ng/mL and Cmax E2 was 42.95 and 77.27 pg/mL for IVR1 and IVR2 groups, respectively. Month 3 median steady state (Css) plasma P4 concentrations were 1.19 and 1.89 ng/mL, and Css E2 was 20.73 and 38.16 pg/mL for IVR1 and IVR2 users, respectively. Both DARE-HRT1 IVRs were safe and released E2 in systemic concentrations, which were in the low, normal premenopausal range. Systemic P4 concentrations predict endometrial protection. Data from this study support further development of DARE-HRT1 for the treatment of menopausal symptoms.

Effect of resistance exercise training on plasma neurofilaments in multiple sclerosis: a proof of concept for future designs.

Multiple sclerosis (MS) is a dysimmune and neurodegenerative disease of the central nervous system that continues to be one of the main causes of non-traumatic disability in young people despite the recent availability of highly effective drugs. Exercise-based interventions seem to have a positive impact on the course of the disease although pathophysiological mechanisms responsible for this benefit remain unclear. This is a longitudinal study to examine the effects of a short-term training program on neurofilament plasma levels, a biomarker of axonal destruction, measured using the ultrasensitive single molecule array (SiMoA). Eleven patients completed a 6-week supervised resistance-training program of 18 sessions that consisted of 3 sets of 8-10 repetitions of 7 exercises. Median plasma neurofilament levels significantly decreased from baseline (6.61 pg/ml) to 1 week after training intervention (4.44 pg/ml), and this effect was maintained after 4 weeks of detraining (4.38 pg/ml). These results suggest a neuroprotective effect of resistance training in this population and encourage us to investigate further the beneficial impact of physical exercise and to emphasize the importance of lifestyle in MS.

COVID-19 Adenoviral Vector Vaccination Elicits a Robust Memory B Cell Response with the Capacity to Recognize Omicron BA.2 and BA.5 Variants.

Following the COVID-19 pandemic, novel vaccines have successfully reduced severe disease and death. Despite eliciting lower antibody responses, adenoviral vector vaccines are nearly as effective as mRNA vaccines. Therefore, protection against severe disease may be mediated by immune memory cells. We here evaluated plasma antibody and memory B cells (Bmem) targeting the SARS-CoV-2 Spike receptor-binding domain (RBD) elicited by the adenoviral vector vaccine ChAdOx1 (AstraZeneca), their capacity to bind Omicron subvariants, and compared this to the response to mRNA BNT162b2 (Pfizer-BioNTech) vaccination. Whole blood was sampled from 31 healthy adults pre-vaccination and 4weeks after dose one and dose two of ChAdOx1. Neutralizing antibodies (NAb) against SARS-CoV-2 were quantified at each time point. Recombinant RBDs of the Wuhan-Hu-1 (WH1), Delta, BA.2, and BA.5 variants were produced for ELISA-based quantification of plasma IgG and incorporated separately into fluorescent tetramers for flow cytometric identification of RBD-specific Bmem. NAb and RBD-specific IgG levels were over eight times lower following ChAdOx1 vaccination than BNT162b2. In ChAdOx1-vaccinated individuals, median plasma IgG recognition of BA.2 and BA.5 as a proportion of WH1-specific IgG was 26% and 17%, respectively. All donors generated resting RBD-specific Bmem, which were boosted after the second dose of ChAdOx1 and were similar in number to those produced by BNT162b2. The second dose of ChAdOx1 boosted Bmem that recognized VoC, and 37% and 39% of WH1-specific Bmem recognized BA.2 and BA.5, respectively. These data uncover mechanisms by which ChAdOx1 elicits immune memory to confer effective protection against severe COVID-19.

#3640 IMMUNORELATED RENAL ADVERSE EFFECTS IN PATIENTS TREATED WITH CHECKPOINT INHIBITORS

Abstract Background and Aims Checkpoint Inhibitors (CPI) use has revolutionized cancer treatment. However, Immuno-Related Adverse Effects (IRAE) occur in more than 50% of patients. At renal level, the initial incidence of IRAE was considered low and later studies suggest between 1.4–4.9%. The aim of the study was to describe a case series with kidney dysfunction related to CPI treatment and report renal and patients’ outcomes after initiation of treatment. Methods We retrospectively studied 28 patients (72.4% male, median age 71.1 years, IR: 40.1–87.3), with metastasic neoplasms (22 advanced lung cancer, 4 melanomas, 1 renal and 1 colon) treated with CPI (Pembrolizumab 75%, 21.4% Nivolumab and 3.6% with Pembrolizumab + Ipilimumab combination) who developed AKI after CPI use, at the Complejo Hospitalario Materno Insular from January 2016 to March 2022. Demographic clinical and analytical data were collected, as well as, the evolution of kidney function. Results Immuno-related AKI occurred after a median of 3.7 months (IR: 0.23–24.0). The median plasma creatinine prior to receiving treatment with CPI was 0.9 mg/dl [IQR: 0.67-1.65]. After initiation of steroids (1mg/kg/day), 85.7% showed recovery of kidney function. Seventeen patients (60.7%) presented complete remission, 8 (28.6%) partial remission, while 3 patients (10.7%) did not recover from kidney function. In patients who did not respond initially to steroid therapy, a renal biopsy was performed (n = 7; 25.9%) showing tubulointerstitial nephritis (TIN) in 5 patients, 1 granulomatous nephritis with poor kidney function evolution, and 1 endocapillary glomerulonephritis together with TIN. More than half of the patients who developed immuno-related ARF presented toxicity in other organs (n = 13; 56.5%); being thyroiditis the most frequent (n = 3; 10.7%). At the end, two patients (7,1%) presented complete remission of neoplasms, 6 (21.4%) partial remission, stability was observed in 8 patients (28,6%), the neoplasm progress in 4 (14,3%) and 8 (28,6%) patients died during the follow-up. Finally, the patient median survival was 36,7 months ((IR 5,7- 79,6) post CPI treatment. Conclusion Immuno-related AKI after use of CPI is low; over two-thirds of patients recovered from total or partial renal function after initiation of steroids. The presence of granulomas in renal biopsy may confer poor prognosis.

#3712 INTRAVASCULAR VOLUMES AND THE INFLUENCE ON ANAEMIA IN PATIENTS UNDERGOING MAINTENANCE HAEMODIALYSIS

Abstract Background and Aims Fluid overload is a major challenge in haemodialysis (HD) patients and might cause hypervolaemia. We speculated that HD patients reaching dry weight could have undetected hypervolaemia and low haemoglobin concentration (Hb) due to haemodilution. Method The study included HD patients (n = 22) and matched healthy controls (n = 22). Blood volume, plasma volume, red blood cell volume, and total haemoglobin mass (Hb mass) were determined using a carbon monoxide (CO)-rebreathing method in HD patients reaching dry weight and controls. Blood volume measurements were also obtained by a dual-isotope labelling technique in a subgroup for validation purposes. Results Blood volume was higher in 16 out of the 22 HD patients compared to controls. In the HD group, the median blood volume was 89.3 mL/kg (interquartile range (IQR) 76.7–95.4 mL/kg) and was higher than in the control group (79.9 mL/kg (IQR 70.4–88.0 mL/kg); P < 0.037) (Table 1). The median plasma volume was 54.7 mL/kg (IQR 47.1–61.0 mL/kg) and 44.0 mL/kg (IQR 38.7–49.5 mL/kg) in the HD and control groups, respectively (P < 0.001). Hb was lower in HD patients (P<0.001), whereas no difference in total Hb mass was observed between groups (P = 0.11). Changes in Hb levels during and after dialysis were observed in the HD group and is shown in Fig. 1. A correlation was found between blood volume measured by the CO-rebreathing test and the dual-isotope labelling technique in the control group (r = 0.83, P = 0.015), but not the HD group (r = 0.25, P = 0.60). Conclusion The HD group had increased blood volume at dry weight due to high plasma volume, indicating a hypervolaemic state. The total Hb mass was similar between HD patients and controls, unlike Hb, which emphasizes that Hb is an inaccurate marker of anaemia among HD patients.

#3911 DIETARY OXALIC ACID INTAKE AND PLASMA OXALIC ACID CONCENTRATION IN PATIENTS WITH CHRONIC KIDNEY DISEASE

Abstract Background and Aims High oxalic acid concentration may be caused by genetic disorders, enteric diseases, but also by kidney insufficiency per se. It may result in kidney oxalic acid stones, kidney function decline, and failure. This study aimed to investigate whether dietary oxalic acid intake influences plasma oxalic acid concentration in a population undergoing kidney transplantation. Method Dietary oxalic acid intake was assessed using a Food Frequency Questionnaire. Based on frequency and portion size, average daily oxalic acid intake in the past year and in the last 24 hours was calculated. A blood sample for determination of plasma oxalic acid concentration was drawn on the operation ward before transplantation. For multivariable analysis seventeen recipient related variables were gathered. Results 418 patients were included. The median age of the participants was 62 year, 60% were male, all had an eGFR <20 ml/min/1.73 m2, and 66% were on dialysis with a median dialysis vintage of 13 months. The median plasma oxalic acid concentration was 32.2 µmol/L (range 4.6-243.2). In 98.3% of patients oxalic acid concentration was above the upper limit of normal. The average oxalic acid intake was 199 mg/day (range 4-1599), while it was 138 mg/day in the last 24 hours before transplantation (range 0-3906). Multivariable linear regression analysis showed that plasma oxalic acid concentrations were significantly higher in recipients with higher average (p<0.001) and last 24 hours oxalic acid intake (p = 0.002), lower age (p<0.001), lower residual diuresis (p<0.001), higher body mass index (p<0.001), longer dialysis vintage (p = 0.032), hemodialysis (p<0.001), and peritoneal dialysis (p<0.001) versus preemptive status. Conclusion In pre-kidney transplant patients, plasma oxalic acid concentration is above upper normal limit in 98.3% of patients and is multifactorially determined. As all other factors are not modifiable, the only way to decrease plasma oxalic acid concentration is dietary restriction.

#2981 IRON DEFICIENCY AND CADMIUM LEVELS IN KIDNEY TRANSPLANT RECIPIENTS

Abstract Background and Aims A higher plasma level of cadmium, a nephrotoxic divalent heavy metal, has been associated with an increased risk of graft failure in kidney transplant recipients (KTRs). The drivers of cadmium toxicity in KTRs are incompletely understood. We hypothesize that iron deficiency (ID) increases cadmium absorption and accumulation by upregulation of divalent metal transporters. Here, we first investigated whether ID is associated with higher plasma cadmium levels. As increased cadmium levels have previously been associated with cancer, cardiovascular disease, and diabetes in other populations, we also examined whether plasma cadmium levels are associated with all-cause mortality in KTRs. Method We used data from stable KTRs ≥1 year after transplantation who participated in the TransplantLines Food and Nutrition Cohort study. Plasma cadmium and iron status parameters, i.e., ferritin, iron, and transferrin saturation (TSAT), were measured at baseline. ID was defined as TSAT<20% and ferritin <300 µg/L. Linear regression analyses were applied to study the association between iron status parameters and cadmium levels. Multivariable Cox regression analyses were used to investigate the association of plasma cadmium levels with all-cause mortality, adjusted for age, sex, BMI, smoking status, history of cardiovascular disease, glucose, HbA1c, systolic blood pressure, eGFR, cholesterol, and ID at baseline. In sensitivity analyses, we repeated these analyses using an alternative definition of ID, TSAT<20% and ferritin<100 µg/L (IDalt). Results We included 670 KTRs (age 53±13 years, 58% males, median 5.4 (IQR, 1.9-11.7) years after transplantation). KTRs with ID (30% of all KTRs, median plasma cadmium level 63 (IQR, 48-76) ng/L) had higher cadmium levels than KTRs without ID (median 56 (IQR, 42-75) ng/L, P = 0.01, Figure 1). ID was not associated with plasma cadmium after adjustment for age, sex, and smoking status. However, within the ID group, TSAT (β = -0.016, P = 0.01) and serum iron (β = -0.023, P = 0.01) were inversely associated with log-transformed cadmium levels, independently of age, sex, and smoking status. Sensitivity analysis yielded similar results: KTRs with IDalt (23% of all KTRs) had higher cadmium levels than KTRs without IDalt (median 61 (IQR, 49-76) ng/L vs median 57 (IQR, 42-75) ng/L, P = 0.03). Furthermore, in Cox regression analysis, KTRs in the highest tertile of plasma cadmium levels (70 ng/L to 330 ng/L) had an increased risk of mortality (hazard ratio 2.80, 95%CI 1.47-5.36, P = 0.01) compared to KTRs in the lowest cadmium tertile (19 ng/L to 48 ng/L) during a median follow-up of 4.9 (IQR, 3.5-5.5) years. No significant interaction by iron status was observed for the association between plasma cadmium and mortality. Conclusion KTRs with ID had higher cadmium levels than KTRs without ID, and higher plasma cadmium levels were independently associated with a higher mortality risk. The association of cadmium with mortality was not different between individuals with and without ID at baseline. Further investigations should determine whether ID correction prevents cadmium accumulation in KTRs.

Long-Term Intake of Linezolid Elevates Drug Exposure and Reduces Drug Clearance and Elimination in Adults With Drug-Resistant Pulmonary Tuberculosis.

Pharmacokinetic (PK) studies are critical for dose optimization, and there is a paucity of linezolid (LZD) PK data for prolonged use in drug-resistant tuberculosis (DR-TB). Therefore, the authors evaluated the pharmacokinetics of LZD at two-time intervals in DR-TB during long-term use. PK evaluation of LZD was performed at the end of the 8th and 16th weeks of treatment in a randomly selected subset of adult pre-extensively drug-resistant pulmonary tuberculosis patients (n = 18) from a multicentric interventional study (Building Evidence to Advance Treatment of TB/BEAT study; CTRI/2019/01/017310), wherein a daily dose of 600 mg LZD was used for 24 weeks. Plasma LZD levels were measured using a validated high-pressure liquid chromatography (HPLC) method. The LZD median plasma C max was comparable between the 8th and 16th weeks [18.3 mg/L, interquartile range (IQR: 15.5-20.8 and 18.8 mg/L, IQR: 16.0-22.7, respectively)]. However, the trough concentration increased significantly in the 16th week (3.16 mg/L, IQR: 2.30-4.76), compared with the 8th week (1.98 mg/L, IQR: 0.93-2.75). Furthermore, compared with the 8th week, in the 16th week, there was a significant increase in drug exposure (AUC 0-24 = 184.2 mg*h/L, IQR: 156.4-215.8 versus 233.2 mg*h/L, IQR: 187.9-277.2), which corroborated with a longer elimination half-life (6.94 hours, IQR: 5.55-7.99 versus 8.47 hours, IQR:7.36-11.35) and decreased clearance (2.91 L/h, IQR: 2.45-3.33 versus 2.19 L/h, IQR: 1.49-2.78). Long-term daily intake of 600 mg LZD resulted in a significant elevation in trough concentration (>2.0 mg/L) in 83% of the study participants. Furthermore, increased LZD drug exposure may be partly because of decreased clearance and elimination. Overall, the PK data underscore the need for dose adjustment when LZDs are intended for long-term treatment.

Targeting AMP kinase in melanoma: A phase I trial of phenformin with dabrafenib/trametinib.

9536 Background: AMP-activated protein kinase (AMPK) can phosphorylate BRAF and block its activation of MEK. AMPK is activated by biguanides such as metformin and phenformin (phen). Preclinical data indicated that phen can enhance the effects of BRAF inhibitors (BRAFi) in sensitive and BRAFi-resistant melanoma (mel) cell lines whereas metformin does not. Phen also can decrease myeloid-derived suppressor cells (MDSCs) enhancing immune reactivity against mel. For these reasons, we designed a phase I trial combining phen with dabrafenib/trametinib (dab/tram) in patients (pts) with metastatic BRAF V600-mutated mel. Methods: Bulk phen was provided by the Division of Cancer Treatment and Diagnosis of the National Cancer Institute under a materials transfer agreement. Phen was encapsulated at the Pharmaceutical Product Facility at MSKCC under cGMP procedures and used under an IND held by MSKCC. Eligible pts had metastatic BRAF V600-mutated mel. For the dose-escalation phase, prior BRAFi therapy was allowed. A 3+3 dose escalation design was used starting at a phen dose of 50 mg bid and standard dosing of dab/tram (150 mg bid/2 mg qd). Subsequent planned dose levels were 100 mg bid, 200 mg bid, and 300 mg bid with de-escalation to intermediate doses for toxicity. Plasma PK samples were collected and assayed by MRI Global Inc using a validated, GLP-compliant, HPLC-MS/MS assay. PBMC were collected to measure circulating MDSCs. At the recommended phase 2 dose (RP2D), we planned to treat 10 BRAFi-naïve pts. Results: We accrued 18 patients from March 2017 through December 2019. Dose-escalation to 200 mg bid was not tolerable nor was 150 mg bid. Therefore, we determined 100 mg bid to be the RP2D and accrued 2 patients on the dose expansion cohort before further accrual became impossible due to the COVID-19 pandemic. The most common toxicities were gastrointestinal – nausea, vomiting, anorexia, and transaminase and alkaline phosphatase elevation – accounting for 9 DLTs. Two patients were hospitalized due to lactic acidosis. There were also constitutional/inflammatory and skin/mucosal adverse events thought to be related to dab/tram. Weight loss was seen in most patients (median 3.7% at week 8) thought to be related to phen. There were 8 PRs and 2 CRs. Responses were observed in 2/7 pts who had received prior therapy with BRAFi. One CR lasted > 1 year. There were 8/11 (73%) responders among the BRAFi-naïve pts. At the RP2D of 100 mg bid, day 8 median phen plasma level was 73.4 ng/ml (range 32.8-253.2). At the the 50 mg bid dose level, it was 40.8 ng/ml (range 29.7-110.2). MDSC could be analyzed from the 150 mg bid and 200 mg bid dose levels (N = 7 pts). In all but 1 pt, MDSCs decreased while on phen. Conclusions: We observed 10/18 (55.5%) total responses with 2/7 among previously treated pts. Circulating MDSCs decreased on treatment. Phen at 100 mg bid can be combined safely with dab/tram and should be explored in future randomized phase II trials. Clinical trial information: NCT03026517 .

Phase 1, randomized, open-label, single-dose, crossover study to evaluate the bioequivalence of four formulations of oral rivoceranib tablets in healthy subjects.

e15122 Background: Rivoceranib is a novel oral tyrosine kinase inhibitor that potently and selectively inhibits VEGFR2. Rivoceranib is being investigated for indications targeted towards solid malignancies as either monotherapy or in combination with other anticancer therapies. Herein, we assessed the bioequivalence of a single dose of rivoceranib administered as 4 different formulations in healthy subjects. Methods: This single-center, open-label, randomized, single-dose, 4-way crossover study evaluated the bioequivalence of 4 different formulations of rivoceranib oral tablets in healthy adults. Each subject participated in 4 treatment periods, where they were randomized to 1 of 4 sequences: ABCD, BDAC, CADB, and DBAC (Formulation A = rivoceranib 250 mg tablet/clinical formulation used in the pivotal phase 3 study, Formulation B = rivoceranib 200 mg tablet/clinical formulation used in early clinical studies, Formulation C = rivoceranib 250 mg tablet/formulation to be developed for future use, Formulation D = rivoceranib 250 mg tablet/to-be-marketed formulation). Results: Of the 60 subjects enrolled, 66.7% were male, 88.3% were white, and median age was 43 years. The median plasma rivoceranib Tmax was similar following all treatments (2 hours post-dose). The 90% CIs around the geometric mean ratios (GMRs) of plasma rivoceranib AUC0-t, AUC0-inf, and Cmax for Formulation B vs. Formulation A and Formulation D vs. Formulation A were within the 80-125% reference interval, demonstrating bioequivalence between Formulation B and Formulation A as well as Formulation D and Formulation A. The 90% CIs around the GMRs of plasma rivoceranib AUC0-t, AUC0-inf, and Cmax for Formulation C vs. Formulation A were slightly outside of the 80%-125% reference interval. Conclusions: Formulations B (clinical formulation used in early clinical studies) and D (to-be-marketed formulation) were bioequivalent to Formulation A (clinical formulation used in the pivotal phase 3 study). Formulation C (formulation to be developed for future use) and Formulation A were similar, but the difference was slightly outside of the bioequivalence criteria. It remains to be evaluated whether the difference in bioavailability between Formulation C and Formulation A is clinically meaningful. Clinical trial information: NCT05287360 . [Table: see text]

DISCREPANCIES IN THE OUTCOME OF PLASMA ALDOSTERONE LEVELS ASSESSED BY IMMUNOASSAY AND MASS SPECTROMETRY - CLINICAL RELEVANCE FOR THE DIAGNOSIS OF PRIMARY HYPERALDOSTERONISM

Objective: To assess potential discrepancies in the clinical interpretation of the salt loading test (SLT) resulting from the assessment of aldosterone concentrations by two different methods - immunoassay and mass spectrometry. Design and method: Eighty-one patients (47F, 34M, mean age 47.7 ± 14.1 years) with suspected primary hyperaldosteronism (PA) who underwent an SLT were included in the ongoing study. Patients had their treatment modified according to current guidelines prior to the test. The SLT was performed in the sitting position and blood samples were taken before and after 4 hours of administration of 2 litres of saline. An aldosterone concentration higher than 61 ng/dL (170 pmol/L) was considered indicative of a diagnosis of PA. Plasma aldosterone concentrations from the same samples were assessed by: (1) chemiluminescence-based immunoassay (CLIA), LIAISON® by DiaSorin, and (2) liquid chromatography-mass spectrometry (LC-MS), MassChrom Chromsystems kit, UHPLC technique using a QTRAP 6500+ instrument (Sciex). Renin concentration was assessed by CLIA. Results: Median plasma aldosterone concentrations after saline administration assessed by CLIA were significantly higher than those assessed by LC-MS (64.4 vs 44.0 ng/dL; p < 0.001). The correlation coefficients for plasma aldosterone concentration after saline administration was 0.69 (p < 0.001). PA was diagnosed by one of the methods in 22 of patients and by both methods in 16 patients. Conflicting results were obtained in 6 patients (7.4%): in 5 patients CLIA was suggestive of PA but LC-MS not and in one patient LC-MS was suggestive of PA but CLIA not. In four cases, plasma aldosterone concentrations were slightly above or below the cut-off values (CLIA vs LC-MS: 62.9 vs 53; 61.9 vs 50; 97.8 vs 61 and 112 vs 58 ng/dL) in at least one of the methods. In the other two cases, the discrepancies were more pronounced (50 vs 80 ng/dL and 126 vs 24 ng/dL). Conclusions: Discrepant results of aldosterone assessment by CLIA and LC-MS methods were obtained in 7.4% of patients. Discrepancies were generally related to borderline results. If a plasma aldosterone concentration value close to the cut-off values is obtained, a repeat determination using another method should be considered.

8-Hydroxy-2'-deoxyguanosine and malondialdehyde in plasma and their association with disease severity in 20 cats with chronic kidney disease.

Oxidative stress is associated with the development and progression of chronic kidney disease (CKD) in humans. The aim of this study was to evaluate the concentrations of oxidative stress markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), in the plasma and urine of cats with different stages of CKD. Plasma and urine samples were collected from cats with CKD that were referred to the Veterinary Medical Center of the University of Tokyo between April 2019 and October 2022. Plasma and urine samples were collected from healthy cats (n = 6 at most), cats with stage 2 CKD (n = 8) and stage 3-4 CKD (n = 12), and cats with idiopathic cystitis (disease control, n = 5). Plasma and urine concentrations of 8-OHdG and MDA were measured using ELISA and thiobarbituric acid reactive substances assay kits, respectively. The median plasma 8-OHdG concentrations were 0.156 ng/ml (<0.125-0.210 ng/ml) in the healthy group, <0.125 ng/ml (range <0.125 ng/ml) in the idiopathic cystitis group, 0.246 ng/ml (range 0.170-0.403 ng/ml) in cats with stage 2 CKD and 0.433 ng/ml (range 0.209-1.052 ng/ml) in cats with stage 3-4 CKD. Concentrations in stage 3-4 CKD were significantly higher than those in the healthy and disease control groups. Plasma MDA concentrations were low in the healthy and disease control groups and significantly higher in cats with stage 3-4 CKD. In every cat with CKD, plasma 8-OHdG and MDA concentrations were positively correlated with plasma creatinine concentrations (8-OHdG, rs = 0.68; MDA, rs = 0.67). Urinary 8-OHdG/urinary creatinine (u-CRE) and urinary MDA/u-CRE levels did not differ significantly between the groups; however, it was difficult to evaluate them because of the small sample size. This report shows that plasma 8-OHdG and MDA concentrations increase with the severity of feline CKD. These markers may be useful for assessing oxidative stress in cats with CKD.

Plasma arginine as a candidate predictive biomarker for response to immune checkpoint inhibition (ICI) in metastatic colorectal cancer (mCRC): Analysis of the CCTG CO.26 trial.

3545 Background: Nutritional stress is one of the mechanisms used by tumour cells to evade the immune system. Arginine (ARG), an amino acid involved in several cellular functions including immunomodulation, is important in regulating T-lymphocyte cell activity and the anti-tumour response. ARG deficiency in the tumour microenvironment has been shown to impair T-cell response while ARG supplementation may promote anti-tumour immune activity. In this exploratory post-hoc analysis of the Phase II CO.26 trial (NCT02870920), we investigated the role of plasma ARG in predicting response to ICI in patients (pts) with refractory mCRC. Methods: CO.26 was a phase II trial which randomized pts with refractory mCRC to durvalumab plus tremelimumab (D+T) versus best supportive care (BSC). Plasma ARG concentrations were determined from blood samples pre-treatment using HPLC-tandem mass spectrometry. The median plasma ARG value was used as a cut-off stratifying pts into ARG-high (≥10650 ng/ml) versus ARG-low ( &lt; 10650 ng/ml) groups. Progression-free (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and compared between groups using the log-rank test. Cox proportional hazard models were used to analyze prognostic and predictive impacts of ARG on PFS and OS. Results: Of 180 pts enrolled in CO.26, 162 pts (N = 115 treated with D+T and 47 BSC) had pre-treatment blood samples for baseline ARG analysis. There were no significant differences in baseline characteristics between pts included in this analysis and the total study pts, or between ARG-high and ARG-low pts. In pts treated with D+T, ARG-high was associated with more favourable prognosis (ARG-high median OS 7.62 months vs. ARG-low 5.49 months, multivariable hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.40-0.91, p = 0.016). In ARG-high pts, D+T significantly improved OS (median OS 7.62 months with D+T vs 3.61 months BSC; HR 0.61, 95% CI 0.37-0.99, p = 0.04). In ARG-low pts there was no OS benefit with D+T (median OS 5.49 months D+T vs 4.27 months BSC; HR 0.84, 95% CI 0.50-1.41, p = 0.51. Interaction p = 0.037). Baseline ARG values had no association with PFS or disease control rate. Conclusions: Baseline plasma ARG was prognostic in pts with mCRC treated with D+T, and high ARG was predictive of improved OS with ICI. Prospective studies should be done to validate ARG as a biomarker identifying mCRC pts likely to derive benefit from ICI. Therapeutic approaches targeting the ARG pathway should be investigated in future studies.

Drinking recommended daily water significantly alters haemato-biochemical parameters in prospective blood donors; a one-center quasi-experimental study in a tropical setting

BackgroundIn sub-Saharan Africa, the prevailing high ambient temperatures should warrant increased daily water intake (DWI) to prevent haemo-concentration and its potential to confound patients' laboratory data. AimTo assess the impact that the recommended DWI has on the haemato-biochemical variables in a tropical setting. Materials and methodsThis quasi-experimental study recruited 101 apparently healthy individuals (18–60 years) in the Bawku municipality. DWI, anthropometrics, and haemato-biochemical variables were assessed at baseline. Participants were encouraged to increase their DWI to ≥4 L over a 30-day period; haemato-biochemical variables were re-evaluated. Total body water (TBW) was anthropometrically estimated. ResultsThe median post-treatment DWI significantly increased; consequently, anaemia cases increased by >20-fold (2.0 % vs 47.5 % post-treatment). RBC count, platelet count, WBC count, and median haemoglobin significantly decreased compared to baseline (p < 0.0001). Biochemically, median plasma osmolality (p < 0.0001), serum sodium (p < 0.0001), serum potassium (p = 0.0012) and random blood sugar (p = 0.0403) significantly decreased. Compared to baseline, significantly higher proportion of participants classified as thrombocytopenic (8.9 % vs 3.0 %), hyponatraemia (10.9 % vs 2.0 %), or normal osmolarity (77.2 % vs 20.8 %). There were differential bivariate correlations between pre- and post-treatment haemato-biochemical variables. ConclusionSub-optimal DWI is a likely confounder in haemato-biochemical data interpretation in the tropics.

Persistent hypovitaminosis D among Italian patients with myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Background Previously we have demonstrated that hypovitaminosis D is common in the Italian population and it has a comparable deleterious effect to diabetes mellitus on survival after an acute myocardial infarction (AMI). Aim Here, we sough to evaluate if the prevalence of hypovitaminosis D changed over time, considering also frequent lockdowns in the last years due to COVID-19 pandemic. Methods Our large population of 1042 patients hospitalized for AMI, were divided into three groups, according to the year of enrollment: group 1 included 368 patients enrolled between 2014-2016, group 2 with 470 patients enrolled between 2017- 2019, and group 3 from 204 patients enrolled in the last three years, 2020-2022). We determined Vitamin D level at hospital admission and we evaluated whether the concentration of vitamin D changed in the last decade. Results The median concentration of vitamin D in our cohort of patients with AMI was 18.2 (11.48-25.73) ng/ml). Throughout the three groups (2014-2016, 2017-2019, 2020-2022), the median plasma vitamin D showed a trend toward an increase (17.3 (10.33 – 24.2) ng/ml, 18.95 (11.6 – 26.73) ng/ml, and 19.05 (12.5 – 27.3) ng/ml respectively), which was significant between the group 1 vs 2 and 3 (p = 0.033 and p = 0.004, respectively), while between the group 2 and 3 did not. Despite the trend of increase, the percentage of patients with hypovitaminosis D in each group remained high (61.4%, 53.8% and 52.0% respectively). As expected, samples taken between May and September have significantly higher vitamin D values compared to ones taken from October to April for each group (the group 1: 21.80 (15.55 – 31.23) ng/ml vs 15.8 (9.22 – 23.98) ng/ml, p &amp;lt; 0.0001; the group 2: 22.05 (14.10 – 30.98) ng/ml vs 16.50 (11.03 – 23.90) ng/ml, p &amp;lt; 0.0001); the group 3: 20.00 (11.90 – 26.90) ng/ml vs 16.30 (9.75 – 22.30) ng/ml, p = 0.001). In all three groups, low levels of Vitamin D were associated with worse outcome as previously we have shown. Conclusions There has been a trend of increasing vitamin D values over the years, but insufficient vitamin D levels persists. We did not observed a decrease of Vitamin D levels, over the pandemic, possibly due to media awareness that emphasized the significance of vitamin D administration against viral infection.

Association between serum level of vitamin D (25-hydroxyvitamin D) and plasma level of vitamin D receptor with bacteriological index in leprosy patients.

Macrophages respond against Mycobacterium leprae infection through interacting with vitamin D and vitamin D receptor (VDR). There has been no study analyzing the association between vitamin D and VDR with bacteriological index (BI) in leprosy patients in Indonesia. To analyze the serum level of 25- hydroxyvitamin D (25(OH)D) and plasma level of VDR as well as their association with BI in leprosy patients in Indonesia. This is a cross-sectional study. Serum level of 25(OH)D was assessed with in vitro chemiluminescent immunoassay. Plasma level of VDR was assessed with enzyme linked immunosorbent assay method. Median serum level of 25(OH)D was 12.68 ng/mL. There was no correlation between serum level of 25(OH)D and BI (r=0.033; p=0.869). Median plasma level of VDR was 1.36 ng/mL. There was no correlation between plasma level of VDR and BI (r=- 0.063; p=0.749) and no significant association between BI and serum level of 25(OH) and plasma level of VDR (R2=0.055). There was no association between serum level of 25(OH)D and plasma level of VDR with BI in leprosy patients.

Thoracic epidural analgesia prolongs postoperative QT interval on electrocardiogram in major non-cardiac surgery: a randomized comparison and a prospective cohort analysis.

Introduction: Prolongation of QT interval on electrocardiogram can be associated with perioperative lethal arrhythmia. Epidural analgesia is a commonly used modality to relieve surgical pain by blocking sensory nerves, which also blocks the autonomic nervous system and can affect QT interval. Since patient monitoring becomes much less frequent after surgery than intraoperative period, we investigated the effects of epidural analgesia on postoperative QT interval with a randomized clinical trial and a prospective cohort study. Methods: In a randomized study, we assigned 60 patients undergoing thoracic epidural analgesia to an epidural analgesia or no-epidural analgesia group, in which 3ml/h of 0.25% epidural levobupivacaine (7.5mg/h) was administered only in the epidural analgesia group during surgery. The primary outcome was the postoperative heart rate-corrected QT interval. In a prospective cohort study, patients were assigned to receive 5ml/h epidural levobupivacaine (12.5mg/h). The plasma concentration of levobupivacaine was measured using liquid chromatography-mass spectrometry. Results: The median postoperative corrected QT interval interval with 3ml/h epidural levobupivacaine was significantly longer than that without epidural analgesia. Using multiple regression analysis for the factors known to affect postoperative corrected QT interval interval, epidural analgesia was found to be an independent variable for prolongation, and the mean difference of the corrected QT interval interval with or without epidural analgesia was 23ms after adjustment. The median plasma concentration of levobupivacaine at the end of surgery was 164ng/ml with 3ml/h epidural levobupivacaine, and the correlation coefficient to the postoperative corrected QT interval interval was 0.14, showing a not significant correlation. A prospective cohort study showed that 5ml/h epidural levobupivacaine significantly prolonged postoperative corrected QT interval interval compared to preoperative baseline. The median plasma concentration of levobupivacaine was 166ng/ml with 5ml/h, the correlation coefficient of which showed no significant correlation. Conclusion: Thoracic epidural analgesia could enhance postoperative corrected QT interval prolongation after general anesthesia. The mechanism is possibly caused by blocking neighboring or part of the cardiac sympathetic nerves, rather than by systemic effects of epidurally administered levobupivacaine. Clinical trial number: UMIN000013347 for the randomized study and UMIN000041518 for the prospective cohort study, which were registered at University hospital Medical Information Network Center.

C86 ASSOCIATION OF PLASMA TMAO VALUES WITH ANOTHER ISCHEMIC EVENT DURING LONG–TERM FOLLOW–UP IN PATIENTS WITH MYOCARDIAL INFARCTION

Abstract Background Elevated plasma trimethylamine N–oxide (TMAO) levels, a metabolite derived from the intestinal microbiota, are closely related to atherosclerosis due to its involvement in increased inflammation, oxidative stress and cholesterol reverse transport. Objectives Blood samples were collected at admission from 81 patients who survived acute myocardial infarction (AMI) and from 10 healthy individuals. TMAO concentrations were measured by means of liquid chromatography–tandem mass spectrometry with an aim to evaluate the predictive value of this biomarker in terms of another major event during long–term follow–up. Results Patients with AMI have significantly higher median plasma TMAO concentration compared to healthy individuals (respectively, 1.62 (1.37 – 2.25) µM vs 0.55 (0.35 – 0.74) µM, p &amp;lt; 0.0001). Considering only patients with AMI, TMAO values positively correlated with pro–inflammatory markers CRP and TNF–α. In addition, TMAO positively correlated with creatinine and negatively correlated with GFR. Moreover, we noted the trend of higher TMAO values among patients with diabetes mellitus compared to patients without (1.68 (1.44 – 5.43) µM vs 1.59 (1.33 – 2.099) µM, p=0.065). During a median follow–up of 61.74 (59.34 – 64.24) months, 10 patients suffered another infarction. Those individuals had significantly higher TMAO values compared to subjects without another ischemic event (respectively, 2.29 (1.60 – 6.49) µM vs 1.60 (1.34 – 2.09) µM, p = 0.026). Kaplan–Meier analysis confirmed that elevated values of TMAO were associated with the risk of another infarction (p=0.029), whereas multivariate Cox regression analysis did not demonstrate the prognostic value of TMAO towards re–infarction probably due to the small cohort. Conclusions Higher plasma TMAO values at admission in patients with AMI are associated with re–infarction at long–term follow–up.

Efficacy of prolonged intravenous lidocaine infusion for postoperative movement-evoked pain following hepatectomy: a double-blinded, randomised, placebo-controlled trial

BackgroundThe analgesic effect of intravenous lidocaine varies with the duration of lidocaine infusion and surgery type. We tested the hypothesis that prolonged lidocaine infusion alleviates postoperative pain in patients recovering from hepatectomy over the first 3 postoperative days. MethodsPatients undergoing elective hepatectomy were randomly assigned to receive prolonged i.v. lidocaine treatment or placebo. The primary outcome was incidence of moderate-to-severe movement-evoked pain at 24 h postoperatively. The secondary outcomes included incidence of moderate-to-severe pain during movement and at rest throughout the first 3 postoperative days, postoperative opioid consumption, and pulmonary complications. Plasma lidocaine concentration was also monitored. ResultsWe enrolled 260 subjects. Intravenous lidocaine lowered the incidence of moderate-to-severe movement-evoked pain at 24 h and 48 h postoperatively (47.7% vs 67.7%, P=0.001; 38.5% vs 58.5%, P=0.001) and reduced movement-evoked pain scores (3.7 [1.7] vs 4.2 [1.6]; mean difference 0.5 [95% confidence interval {CI}: 0.1–0.9]; P=0.018) and morphine equivalent consumption (47.2 [16.7] mg vs 52.6 [19.2] mg; mean difference 5.4 mg [95% CI: 1.0–9.8]; P=0.016) at 24 h postoperatively. Lidocaine also lowered the incidence of postoperative pulmonary complications (23.1% vs 38.5%; P=0.007). Median plasma lidocaine concentrations were 1.5, 1.9, and 1.1 μg ml−1 (inter-quartile ranges: 1.1–2.1, 1.4–2.6, and 0.8–1.6, respectively) after bolus injection, at the end of the surgery, and 24 h postoperatively. ConclusionsProlonged intravenous lidocaine infusion reduced the incidence of moderate-to-severe movement-evoked pain for 48 h after hepatectomy. However, the reduction in pain scores and opioid consumption by lidocaine was below the minimal clinically important difference. Clinical trial registrationNCT04295330.

Large volume plasmapheresis using a single-use immunoadsorption column: A cost-effective approach for desensitization in ABO-incompatible liver transplant.

Liver transplant is a life-saving treatment, but due to the limited availability of suitable liver donors, ABO-incompatible liver transplants (ABOi-LT) are conducted to increase the availability of liver donors. Perioperative desensitization for ABOi-LT is an established strategy to circumvent the risk of graft rejection. A single prolonged session can be performed to achieve the desired titers to avoid using multiple immunoadsorption (IA) columns or off-label reuse of single-use columns. This study retrospectively assessed the effectiveness of a single prolonged plasmapheresis session using IA as a desensitization strategy in live donor liver transplant (LDLT). This retrospective observational study conducted at a center for liver diseases in North India on six ABOi-LDLT patients who underwent single prolonged IA sessions in the perioperative period from January 2018 to June 2021. Median baseline titer in patients was 320 (64, 1024). The median plasma volume adsorbed was 7.5 volumes (4, 8) per procedure, with a mean procedure time of 600 min (310-753). The reduction in titer ranged from 4 log to 7 log reduction per procedure. Two patients developed transient hypotension during the procedure, which was managed successfully. The median duration of pre-transplant hospital stay was 1.5 days (1, 3). Desensitization therapy helps overcome the ABO barrier and decreases the waiting period before a transplant when ABO identical donors are unavailable. A single prolonged IA session reduces the cost of additional IA columns and hospital stay, thus making it a cost-effective approach to desensitization.