Serum Drug Levels Research Articles

Phase Ib pharmacodynamic study of the MNK inhibitor Tomivosertib (eFT508) combined with paclitaxel in patients with refractory metastatic breast cancer.

Preclinical data motivate clinical evaluation of inhibitors of mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1/2). We conducted a phase 1b clinical trial to study target engagement and safety of tomivosertib, a MNK1/2 inhibitor, alone and in combination with paclitaxel. Eligible patients had metastatic breast cancer resistant to standard of care treatments. Biopsies were obtained at baseline and during treatment with tomivosertib, and then tomivosertib was continued with addition of paclitaxel until disease progression or toxicity. Serum drug levels were measured, and pharmacodynamic endpoints included immunohistochemistry, proteomics, translatomics, and imaging mass cytometry. Tomivosertib alone and in combination with paclitaxel was well tolerated. There was no pharmacokinetic interaction between the drugs. We observed a clear reduction in phosphorylation of eIF4E at S209, a major substrate of MNK1/2, and identified tomivosertib-induced perturbations in the proteome, translatome, and cellular populations of biopsied metastatic breast cancer tissue. We conclude that tomivosertib effectively inhibits MNK1/2 activity in metastatic breast cancer tissue, and that it can safely be combined with paclitaxel in future phase II studies. We demonstrate feasibility of using proteomic profiles, translatomic profiles, and spatial distribution of immune cell infiltrates for clinical pharmacodynamic studies.

Sex-dependent variability of isoniazid and rifampicin serum levels in patients with tuberculosis.

Drug-sensitive TB (DS-TB) is treated with isoniazid, rifampicin, ethambutol, and pyrazinamide. Factors like fast-metabolizing enzymes, malabsorption, and drug interactions can influence serum drug levels. Current TB treatment guidelines recommend weight-adapted dosing without considering sex differences. This study examines drug levels of isoniazid and rifampicin in TB patients treated between 2019 and 2023 at our center focusing on sex-specific aspects. Patients diagnosed with TB and available serum levels of isoniazid or rifampicin between 2019 and 2023 were retrospectively identified. Serum levels were measured using liquid chromatography-mass spectrometry and high-performance liquid chromatography. Patients were stratified by sex and a linear regression mixed effect model was used to assess predictors for different serum levels. The study included 281 single therapeutic drug monitoring (TDM) measurements from 59 patients (28 women, 47.5%). For isoniazid, no sex-specific differences in serum drug levels were identified. On the other hand, female sex was a significant predictor of higher rifampicin plasma levels (coefficient 4.16, 95% CI 0.74-7.59, p = 0.009). Only 38.2% of rifampicin serum level measurements in male patients were within target range, the majority (40/68, 58.8%) were below range and only 2 (2.9%) TDM-levels were above range. Women displayed higher overall rifampicin serum levels than men (median 13.7mg/l vs. 7.1mg/l, p = 0.04), although weight adjusted doses were not significantly different (median 10.0mg/kg vs. 9.8mg/kg p = 0.56). Adverse effects were noted in 42.9% (42/98) of measurements in women and 29.5% (54/183) of measurements in men (p = 0.03). Rifampicin levels were significantly lower in men compared to women, despite weight-adjusted dosing. Clinicians should consider TDM and potential sex differences when treating patients with TB.

Chronic polypharmacy, monotherapy, and deprescribing: Understanding complex effects on the hepatic proteome of aging mice.

Polypharmacy (use of ≥5 concurrent medications) is highly prevalent among older adults to manage chronic diseases and is linked to adverse geriatric outcomes, including physical and cognitive functional impairments, falls, frailty, hospitalization, and mortality. Deprescribing (withdrawal) is a potential strategy to manage polypharmacy. The broad molecular changes by which polypharmacy causes harm and deprescribing may be beneficial are unknown and unfeasible to study rigorously in tissue from geriatric patients. Therefore, in a randomized controlled trial, we administered therapeutic doses of commonly used chronic medications (oxycodone, oxybutynin, citalopram, simvastatin, or metoprolol) as monotherapy or concurrently (polypharmacy) from middle-age (12 months) to old-age (26 months) to male C57BL/6J (B6) mice and deprescribed (gradually withdrew) treatments in a subset from age 21 months. We compared drug-related hepatic effects by applying proteomics along with transcriptomics and histology. We found that monotherapy effects on hepatic proteomics were limited but significant changes were seen with polypharmacy (93% unique to polypharmacy). Polypharmacy altered the hepatic expression of proteins involved in immunity, and in drug, cholesterol, and amino acid metabolism, accompanied by higher serum drug levels than monotherapies. Deprescribing not only reversed some effects but also caused irreversible and novel changes in the hepatic proteome. Furthermore, our study identified several hepatic protein co-expressed modules that are associated with clinically relevant adverse geriatric outcomes, such as mobility, frailty, and activities of daily living. This study highlights the complex molecular changes following aging, chronic polypharmacy, and deprescribing. Further exploration of these mechanistic pathways may inform management of polypharmacy and deprescribing in older adults.

Factors Associated with the Development of Anti-drug Antibodies to TNFi and the Consequences for Axial Spondyloarthritis: A Two-year Follow-up Study.

To evaluate the development of anti-drug antibodies (ADAb) against tumor necrosis factor inhibitors (TNFi) therapy during a 2-year period and search the factors linked to patients with axial spondyloarthritis (axSpA). Biologic-naive patients with axSpA were included in this observational study. Serum drug levels and ADAb were measured at weeks 12, 24, 52, and 104 of treatment by enzyme-linked immunosorbent assay (ELISA). The development of ADAb and factors related to ADAb over time were investigated using generalized estimating equations (GEE). A total of 180 patients with axSpA (116 male, mean (±SD) 45.6 (±11.9) years) who started TNFi treatment (etanercept (32.2%), adalimumab (27.2%), golimumab (20.6%), infliximab (20%)) were included. In the etanercept treatment group, only 1 patient had ADAb at 12 weeks and 24 weeks. Anti-drug antibodies against TNFi drugs were present in the adalimumab group in 32.7% of patients and in the infliximab group in 21.2% of patients at 12 weeks, and the proportion of ADAb-positive patients were found to be stable throughout the follow-up for adalimumab- and infliximab-treated patients. In the golimumab group, one patient had ADAb against golimumab at 12 weeks and the proportion of ADAb-positive patients increased throughout follow-up. In longitudinal analysis, baseline age, TNFi type, longitudinal Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and ASDAS-CRP scores, serum C-eeactive protein (CRP) levels, presence of adverse events and treatment discontinuation were associated with the presence of ADAb. The development of ADAb against TNFi therapy is associated with younger age, high disease activity, the development of adverse events and more common treatment discontinuation in patients with axSpA during 2-year follow-up.

Measuring the impact: Severity of harm from laboratory errors in 195 tests.

This study aimed to objectively assess the potential severity of harm associated with erroneous results in 195 laboratory tests by surveying 514 specialist physicians and medical biochemistry experts. The survey obtained participants' (75 medical biochemists, 439 clinicians) opinions on severity of harm for the erroneous results of 195 tests. The comprehensive list of errors and their effects on test results were obtained from the literature, and then matched with severity of harm scores, from 1 (negligible effect) to 5 (life-threatening injury/death), obtained from the survey responses. Participants perceived tests such as cardiac biomarkers, blood gases, coagulation parameters (activated partial thromboplastin time, prothrombin time, international normalized ratio, and dimerized plasmin fragment D), critical ions (potassium, sodium), toxic trace elements (lead, mercury), and specific serum drug levels (lithium, digoxin) to have a greater potential for patient harm in case of errors. Medical biochemistry specialists assigned higher severity scores to some laboratory tests, including total bilirubin, pseudocholinesterase, platelet indices, and some drug levels (cyclosporine, methotrexate, vancomycin). A substantial agreement (91%) was observed between medical biochemists and clinicians in terms of the most frequently chosen severity of harm score. The study provided objective severity scores and identified high-risk tests for targeted quality improvement.

Verification of successful maintenance by serum drug level during a guided antipsychotic reduction to reach minimum effective dose (GARMED) trial.

Inconsistent results regarding the risk of relapse and better subjective outcomes of previous antipsychotic dose reduction trials in patients with remitted psychosis have not been verified using therapeutic drug monitoring (TDM). This study examined plasma drug concentrations of a dose-tapering trial which exhibited the potential of successful maintenance under lower antipsychotic dosages. A 2-year open-label randomized prospective trial recruited remitted patients to undergo guided antipsychotic tapering. Blood samples were collected at baseline, annually, and after each dose reduction. Plasma aripiprazole/dehydroaripiprazole concentrations were determined using LC-MS/MS. The relationship between the dose and serum drug levels was examined using Spearman's correlation. Divided at 120 ng/mL, relapse rate, global function, quality of life, and psychopathology were compared between high- and low- drug level groups. A total of 126 blood samples were collected, after excluding13 samples due of non-adherence. The correlation coefficients between dosage and drug level were 0.853 (aripiprazole) and 0.864 (dehydroaripiprazole), and the dose and concentration plots were parallel along the tapering trajectories, except patients with non-adherence. The concentration-to-dose ratio of aripiprazole in this cohort, 17.79 ± 7.23 ng/mL/mg, was higher than that in Caucasian populations. No significant differences were observed in the clinical outcomes between the high- and low-level groups. Remarkably, 12 of 15 patients maintained remission at plasma aripiprazole concentrations of <120 ng/mL. The lower-than-expected doses reached in our antipsychotic tapering trial were substantiated to provide adequate prophylactic effects by TDM results in a subset of patients treated with aripiprazole, even considering the differences in pharmacogenomics between ethnicities.

Intraperitoneally Administered Vancomycin Results in Suboptimal Serum and Peritoneal Effluent Drug Levels in Patients with PD-related Peritonitis

Background Intraperitoneal vancomycin is commonly used to treat peritoneal dialysis (PD)-related peritonitis. Therapeutic drug level monitoring helps optimize the use of vancomycin in CKD patients. We studied whether sufficient serum levels were achieved in patients with PD-related peritonitis treated with the commonly used dose of vancomycin in patients with end stage renal disease. Materials and Methods All consecutive patients with PD-related peritonitis during 19 months were studied. Patients received IP Vancomycin 15 mg/kg Q96H and amikacin 2 mg/kg while awaiting culture reports. Vancomycin concentration in serum and dialysate was determined by a validated liquid chromatography-tandem mass spectrometry assay at 1, 12, 24, and 96 h. The primary outcome was the drug levels in serum and peritoneal fluid, and the secondary outcome was peritonitis treatment failure. Results A total of 45 episodes of PD-related peritonitis were treated, of which 41 fulfilled the inclusion criteria and were included in the PK analysis. Recommended serum vancomycin trough level of &gt;15 mg/L was achieved in only two cases. Twenty-one episodes required catheter removal. Conclusion In patients with PD-related peritonitis, intermittent intraperitoneal administration of 15 mg/kg of vancomycin every 96 h does not achieve the recommended serum and dialysate levels of vancomycin. There is an urgent need for pharmacokinetic studies on commonly used IP antibiotics in the PD population to facilitate correct dose recommendations.

Influence of rheumatoid factor levels and TNF inhibitor structure on secondary nonresponse in rheumatoid arthritis patients.

The EXXELERATE study revealed poorer clinical outcomes in patients treated with adalimumab (ADL) and baseline rheumatoid factor (RF) above 203 IU/mL. However, responses were similar in patients treated with certolizumab pegol (CZP) regardless of RF levels. This study investigated the impact of RF levels >203 IU/mL on TNF inhibitors (TNFi) serum levels and the association with secondary nonresponse in RA patients treated with TNFi. We performed an observational ambispective study with RA patients treated with infliximab (IFX), ADL, or CZP. Patients were stratified according to baseline RF levels: ≤ or >203 IU/mL. After 6 months, serum drug levels and antidrug antibodies were measured, and reasons for discontinuation were collected. We included 170 RA patients: 90 (53%) received IFX, 48 (28%) ADL, and 32 (19%) CZP. While CZP serum levels did not differ between RF groups at 6 months (p = 0.6), RF levels >203 IU/mL were linked to lower serum drug levels in patients treated with IFX (p = 0.09) or ADL (p = 0.02). Secondary nonresponse was 3.6 times higher in patients with high versus low RF levels in patients under IFX or ADL. However, the reasons for withdrawal were not affected by RF levels in patients treated with CZP. Baseline RF above 203 IU/mL is associated with lower serum drug levels and an increased risk of discontinuation due to secondary nonresponse in patients treated with IFX or ADL. In contrast, drug levels and clinical outcomes are not significantly impacted by baseline RF levels in patients under CZP.

Pharmacokinetics of ganciclovir eye drops: a comparative study of solutions prepared from ganciclovir for intravenous infusion and ganciclovir gel.

To evaluate the pharmacokinetics of ganciclovir eye drops by comparing solutions prepared from ganciclovir for intravenous infusion and ganciclovir gel and to assess the impact of systemic administration on drug levels in ocular tissues and serum. Experimental study design. Ganciclovir solutions (0.5% and 1.0%) prepared by diluting DENOSINE ® IV Infusion in saline and 0.15% ganciclovir gel (Virgan®) were topically administered in rabbit eyes, with and without concomitant systemic administration of ganciclovir. The concentrations of ganciclovir in the corneal epithelium, stroma, and endothelium, aqueous humor; and blood plasma were analyzed by high-performance liquid chromatography (HPLC). The ganciclovir solutions (0.5% and 1.0%) maintained therapeutic ganciclovir levels in the corneal endothelium above the effective dose required for 50% inhibition (ED50) up to 6h, albeit with a swift decline thereafter. The 0.15% ganciclovir gel maintained higher therapeutic concentrations in the corneal endothelium for up to 12h, exceeding the ED50. Serum concentrations of ganciclovir were significantly elevated in the groups receiving combined systemic administration. Topical application of 0.15% ganciclovir gel maintained high endothelial concentrations, well above the therapeutic threshold, with or without systemic administration. Furthermore, the observed increase in ganciclovir levels within the plasma and aqueous humor following systemic administration posits it as a viable strategy for severe cases of cytomegalovirus corneal endotheliitis or those inadequately managed by local treatments alone.

Relationship between Ustekinumab trough concentrations and clinical, biochemical and endoscopic outcomes in Crohn's disease: A multi-center nationwide retrospective study (TARGET STUDY).

Ustekinumab has been shown to be effective in inducing and maintain clinical and endoscopic remission in Crohn disease (CD). We aim to assess whether ustekinumab trough levels are associated with improved outcomes in CD in real-life. We recruited patients with CD who were treated with ustekinumab for at least 6 months from January 2017 to June 2023. Patients received ustekinumab 6 mg/kg intravenous induction followed by 90 mg every 4-, 8-, or 12-weeks during maintenance were included. We assessed clinical, biochemical, and endoscopic outcomes. Trough concentrations of ustekinumab that were taken from week 42 to week 52 were measured. Primary outcome was to evaluate the relationship between ustekinumab trough concentrations and clinical remission, biochemical normalization, and endoscopic remission. Logistic regression was conducted to assess outcomes. A total of 137 patients with CD, median age of 32 years and 83 (60.6%) males. The median serum levels of ustekinumab measured was 7.2 mcg/mL (interquartile range [IQR] 3.1-9.6). Using Spearman correlation analysis, a strong negative correlation was observed between ustekinumab drug levels and simple endoscopic score (SES-CD) (r = -0.464, P < .001). Additionally, ustekinumab drug levels demonstrated substantial negative correlations with disease severity measured by Harvey-Bradshaw index (HBI) score (r = -0.582, P < .001), C-Reactive Protein (CRP) levels (r = -0.598, P < .001) and fecal calprotectin (FC) levels (r = -0.529, P < .001). A multivariable analysis adjusted for age, sex and body mass index (BMI) showed a significant association between ustekinumab serum drug levels and predefined outcomes. Ustekinumab serum drug level above 4.5 mcg/mL was associated with 24% increase in the likelihood of having an SES-CD score <3 (OR 1.24, confidence interval [CI] 1.12-1.37, P value < .001), 44% more likely to achieve HBI score <5 (OR 1.44, CI 1.26-1.65, P value < .001), 52% higher likelihood of CRP more than 10 (OR 1.52, CI 1.31-1.77, P < .001), and 42% increased likelihood of FC more than 250 (OR 1.42, CI 1.24-1.62, P < .001). Ustekinumab trough concentrations above 4.5 mcg/mL were associated with clinical, biochemical and endoscopic remission in CD. Prospective data is warranted to confirm these findings.

Predicting efficacy of antiseizure medication treatment with machine learning algorithms in North Indian population

PurposeThis study aimed to develop a classifier using supervised machine learning to effectively assess the impact of clinical, demographical, and biochemical factors in accurately predicting the antiseizure medications (ASMs) treatment response in people with epilepsy (PWE). MethodsData was collected from 786 PWE at the Outpatient Department of Neurology, Institute of Human Behavior and Allied Sciences (IHBAS), New Delhi, India from 2005 to 2015. Patients were followed up at the 2nd, 4th, 8th, and 12th month over the span of 1 year for the drugs being administered and their dosage, the serum drug levels, the frequency of seizure control, drug efficacy, the adverse drug reactions (ADRs), and their compliance to ASMs. Several features, including demographic details, medical history, and auxiliary examinations electroencephalogram (EEG) or Computed Tomography (CT) were chosen to discern between patients with distinct remission outcomes. Remission outcomes were categorized into ‘good responder (GR)’ and ‘poor responder (PR)’ based on the number of seizures experienced by the patients over the study duration. Our dataset was utilized to train seven classical machine learning algorithms i.e Extreme Gradient Boost (XGB), K-Nearest Neighbor (KNN), Support Vector Classifier (SVC), Decision Tree (DT), Random Forest (RF), Naïve Bayes (NB) and Logistic Regression (LR) to construct classification models. ResultsOur research findings indicate that 1) among the seven algorithms examined, XGB and SVC demonstrated superior predictive performances of ASM treatment outcomes with an accuracy of 0.66 each and ROC-AUC scores of 0.67 (XGB) and 0.66 (SVC) in distinguishing between PR and GR patients. 2) The most influential factor in discerning PR to GR patients is a family history of seizures (no), education (literate) and multitherapy with Chi-square (χ2) values of 12.1539, 8.7232 and 13.620 respectively and odds ratio (OR) of 2.2671, 0.4467, and 1.9453 each. 3). Furthermore, our surrogate analysis revealed that the null hypothesis for both XGB and SVC was rejected at a 100 % confidence level, underscoring the significance of their predictive performance. These findings underscore the robustness and reliability of XGB and SVC in our predictive modelling framework. SignificanceUtilizing XG Boost and SVC-based machine learning classifier, we successfully forecasted the likelihood of a patient's response to ASM treatment, categorizing them as either PR or GR, post-completion of standard epilepsy examinations. The classifier’s predictions were found to be statistically significant, suggesting their potential utility in improving treatment strategies, particularly in the personalized selection of ASM regimens for individual epilepsy patients.

Combating bacterial resistance to Meropenem by infusion strategy applied to septic burn patients with vasopressor requirements or acute kidney injury to achieve the target

Introduction: Faced with the growing challenge to the use of antimicrobials for the adequate and effective therapy of nosocomial infections, international health agencies have reinforced that combating bacterial resistance and preventing the development of multidrug-resistant (MDR) strains are urgent, since a significant increase based on minimum inhibitory concentration (MIC) for therapeutic agents were reported by the committee of hospitals infection. Meropenem, a carbapenem agent, is widely prescribed for therapy of septic shock caused by susceptible Gram-negative bacteria. In general, the prolonged 3-hrs-infusion has been widely applied in these patients over the past 10 years providing coverage only against susceptible Gram-negative pathogens (MIC 2 mg/L), extended also to intermediate susceptible strains up to MIC 4 mg/L, according to Clinical Laboratory Standard Institute (CLSI database). However, new strategies have been recommended to combat the development of resistance to pathogens isolated from cultures to increase the coverage of this carbapenem agent up to MIC 8 mg/L, to avoid mutant selection with death in ICU. Subject: Clinical protocol was carried out to investigate the efficacy &amp; safety of meropenem at the dose regimen recommended 1g q8h by prolonged infusion, based on serum levels and on cultures monitoring of isolates. Aim of protocol was to assess pharmacodynamics (PD) based on changes of pharmacokinetics (PK), which could affect the coverage of meropenem in septic burns patients with increased or decreased renal function. Pharmacokinetic-pharmacodynamics (PK/PD) tools were applied to investigate efficacy &amp; safety. Methods-clinical protocol: Forty-eight major septic burn patients with high variability on renal function in ICU were included. Cultures were collected before meropenem therapy starts; all of them had nosocomial infection caused by Gram-negative pathogens isolated. Patients undergoing meropenem therapy at the initial stage of septic shock from day-0 to day-8 (D0-D8) and at the late stage of septic shock from day 8 to day 14 (D-8 to D-14) were investigated according to dose requirements based on creatinine clearance, drug serum levels (TDM), and coverage up to MIC 8 mg/L, dose dependent on renal function. Results: Coverage occurred for all patients of both groups after the extended infusion against susceptible Gram-negative strains up to MIC 2 mg/L (minimum inhibitory concentration), and up to MIC 4 mg/L, strains of intermediate susceptibility, according to Clinical Laboratory Standards Institute (CLSI, database) of our hospital. It was demonstrated in patients with renal function augmented by vasopressors, the superiority on coverage by trice that occurred in 24/27 patients (89%) after 4 hrs.-infusion at TDM3 against strains MIC 8 mg/L by comparison with coverage registered in 12/39 patients (30%) after 3 hrs.-infusion at TDM2. On the other hand, meropenem dose regimen must be adjusted to 1g q24h in patients with AKI to guarantee effectiveness &amp; safety in those patients. In addition, after continuous venovenous haemodialysis-filtration (CVVHDF) installed in those patients, meropenem PK/PD target was attained up to MIC 8 mg/L in patients with the empirical dose regimen recommended of 1g q8h, 3hrs.-infusion. Conclusion: Precision medicine guarantees meropenem serum levels combined with cultures monitoring; consequently, must be applied routinely to guarantee coverage against Gram-negative nosocomial pathogens susceptible including strains of intermediate susceptibility (MIC 4-8 mg/L) to avoid mutant selection. Therefore, effective, and safe antimicrobial therapy for patients in septic shock, combined with a continuous monitoring of inflammatory biomarkers, should guide clinical management to ensure cure with early ICU discharge.

Effect of Therapeutic Drug Monitoring on Adherence and Blood Pressure: A Multicenter Randomized Clinical Trial.

Drug concentration in blood or urine is an acknowledged method to detect nonadherence. Observational studies suggest that informing patients about low or absent serum drug levels improves blood pressure (BP). We performed a multicenter randomized clinical trial to test the hypothesis that therapeutic drug monitoring (TDM) could improve drug adherence and BP in patients with uncontrolled hypertension (HT). Patients were ≥18 years on stable treatment with at least 2 antihypertensive agents. We planned to randomize 80 nonadherent patients with a systolic daytime ambulatory BP ≥135 mm Hg to TDM intervention or not. The control group and the study personnel who measured BP remained uninformed about serum drug measurements throughout. All patients and physicians were blinded for BPs. Lifestyle advice and detailed information on the disease process and the importance of BP treatment were given to both groups. From 2017 to 2022, we randomized 46 diagnosed nonadherent from a total of 606 patients with uncontrolled HT. The TDM group had a 6.7 (±14.5) mm Hg reduction from 147.9 (±10.3) to 141.1 (±14.1) mm Hg, and the control group experienced a 7.3 (±13.2) mm Hg reduction from 147.1 (±9.2) to 139.1 (±17.4) mm Hg, P = 0.9 between groups. Adherence improved in both groups, 73% in the TDM group and 59% in the control group became adherent at 3 months, P = 0.51. In our prospective multicenter clinical trial of uncontrolled and nonadherent hypertensive patients, we found no additional effect of TDM on BP and drug adherence compared with standard care. Trial Number NCT03209154, www.clinicaltrials.gov.

Superior suppression of serum estrogens during neoadjuvant breast cancer treatment with letrozole compared to exemestane

PurposeThe aromatase inhibitor letrozole and the aromatase inactivator exemestane are two of the most pivotal cancer drugs used for endocrine treatment of ER-positive breast cancer in all phases of the disease. Although both drugs inhibit CYP19 (aromatase) and have been used for decades, a direct head-to-head, intra-patient-cross-over comparison of their ability to decrease estrogen synthesis in vivo is still lacking.MethodsPostmenopausal breast cancer patients suitable for neoadjuvant endocrine therapy were randomized to receive either letrozole (2.5 mg o.d.) or exemestane (25 mg o.d.) for an initial treatment period, followed by a second treatment period on the alternative drug (intra-patient cross-over study design). Serum levels of estrone (E1), estradiol (E2), letrozole, exemestane, and 17-hydroxyexemestane were quantified simultaneously using a novel, ultrasensitive LC–MS/MS method established in our laboratory.ResultsComplete sets of serum samples (baseline and during treatment with letrozole or exemestane) were available from 79 patients, including 40 patients starting with letrozole (cohort 1) and 39 with exemestane (cohort 2). Mean serum estrone and estradiol levels in cohort 1 were 174 pmol/L and 46.4 pmol/L at baseline, respectively. Treatment with letrozole suppressed serum E1 and E2 to a mean value of 0.2 pmol/L and 0.4 pmol/L (P < 0.001). After the cross-over to exemestane, mean serum levels of E1 and E2 increased to 1.4 pmol/L and 0.7 pmol/L, respectively. In cohort 2, baseline mean serum levels of E1 and E2 were 159 and 32.5 pmol/L, respectively. Treatment with exemestane decreased these values to 1.8 pmol/L for E1 and 0.6 pmol/L for E2 (P < 0.001). Following cross-over to letrozole, mean serum levels of E1 and E2 were significantly further reduced to 0.1 pmol/L and 0.4 pmol/L, respectively. Serum drug levels were monitored in all patients throughout the entire treatment and confirmed adherence to the protocol and drug concentrations within the therapeutic range for all patients. Additionally, Ki-67 values decreased significantly during treatment with both aromatase inhibitors, showing a trend toward a stronger suppression in obese women.ConclusionTo the best of our knowledge, we present here for the first time a comprehensive and direct head-to-head, intra-patient-cross-over comparison of the aromatase inhibitor letrozole and the aromatase inactivator exemestane concerning their ability to suppress serum estrogen levels in vivo. All in all, our results clearly demonstrate that letrozole therapy results in a more profound suppression of serum E1 and E2 levels compared to exemestane.

Antibiotics influence the risk of anti-drug antibody formation during anti-TNF therapy in Chinese inflammatory bowel disease patients.

Aims: The formation of anti-drug antibodies (ADAs) during anti-tumor necrosis factor (anti-TNF) therapy is reported to lead to reducing serum drug levels, which may bring about a loss of response to treatment. Previous research has suggested an association between specific antibiotic classes and ADA formation during anti-TNF therapy. However, there are few studies specifically examining this association in Chinese inflammatory bowel disease (IBD) patients. Therefore, our study aimed to evaluate the possible effect of antibiotic use on ADA formation to anti-TNF therapy in Chinese patients with IBD. Methods: A total of 166 patients with IBD, including 149 with Crohn's disease (CD) and 17 with ulcerative colitis (UC), were included in this retrospective analysis. These patients were initially treated with anti-TNF therapy (infliximab or adalimumab) after January 2018 and reviewed with available ADA levels before October 2023. After univariable analysis of all the variables, a multivariate Cox proportional hazards model was used to assess the association between antibiotic use and ADA development. Results: Among 166 IBD patients treated with infliximab (108/166, 65.1%) or adalimumab (58/166, 34.9%), 31 patients (18.7%) were measured as positive ADA levels. Cox proportional hazard model demonstrated an increased risk of ADA formation in IBD patients who used β-lactam-β-lactamase inhibitor combinations (BL-BLIs) (HR = 5.143, 95%CI 1.136-23.270, p = 0.033), or nitroimidazoles (HR = 4.635, 95%CI 1.641-13.089, p = 0.004) during 12months before the ADA test. On the contrary, a reduced risk was noted in patients treated with fluoroquinolones (HR = 0.258, 95% CI 0.072-0.924, p = 0.037). Moreover, the median serum infliximab or adalimumab concentration in patients with positive ADA levels was significantly lower than that in patients with negative ADA levels (infliximab: 0.30 vs. 1.85μg/mL, p < 0.0001; adalimumab: 0.45 vs. 7.55μg/mL, p = 0.0121). Conclusion: ADA development is associated with various antibiotic classes. BL-BLIs and nitroimidazoles might increase the risk of ADA formation during anti-TNF therapy in Chinese IBD patients, while the treatment with fluoroquinolones could probably reduce such risk. There were certain limitations in the retrospective analysis of the study, therefore, the results are just for reference, and other studies are needed to further confirm our findings.

Abstract 5938: Development of HH044, an orally bioavailable nNOS inhibitor, for the treatment of cutaneous melanoma

Abstract Background: Human cutaneous melanoma is one of the few cancers in which the incidence rate continues to increase, and despite recent advances in immune and targeted therapies, the 5-year survival rate of metastatic disease remains low. Neuronal nitric oxide synthase (nNOS) has been identified to contribute to melanoma development, stimulating disease progression, and facilitating escape of melanoma cells from the immune response. We developed a novel small molecule, HH044, which specifically inhibits nNOS activity and reduced nitric oxide production in melanoma cells. We aim to conduct a proof-of-concept study using our nNOS inhibitor administered orally for anti-melanoma treatment. Methods: Human melanoma cell lines (A375, Sk-Mel-28, wm3211) were employed to analyze the anti-cancer activities of HH044 in vitro. An immune-competent syngeneic melanoma mouse model was used to determine the anti-tumor activity of HH044 when administered orally (50 mg/kg/day) or intraperitoneally (10 mg/kg/day) for 21 days. A pharmacokinetic study of drug levels in serum and tumor samples was conducted after a single dose given intraperitoneally or orally using LC-MS/MS analysis at different time points. Results: HH044 has high selectivity of nNOS over iNOS (340-fold) and eNOS (540-fold). The IC50 of HH044 in melanoma cell lines was 5.27 ± 3.3 μM, while iNOS inhibitor 1200W did not exhibit any cytotoxicity up to 100 μM concentration. Of note, nNOS blockade by HH044 did not result in reactivation of iNOS, and expression levels of iNOS were not changed after HH044 treatment. In vivo studies demonstrated that HH044 treatment given intraperitoneally exhibited potent anti-tumor activity and reduced tumor weight to 45% of control. When administered orally, HH044 at 50 mg/kg significantly reduced tumor growth to 61% of control and extended mice median survival from 32 days to 53 days. Pharmacokinetic analysis showed that oral administration achieved sufficient drug levels in xenograft tumors, which were well above the Ki value (0.005 μM) despite a wide range of bioavailability. The drug level peaked at 2 hours after a single dose (2.27 ± 0.666 μM in the tumor and 23.68 ± 17.43 μM in the serum). Intraperitoneal injection achieved much higher levels in serum and tumor samples, which also declined slower compared to oral gavage administration. By 24 hours, the drug levels in serum and xenograft tumors remained at 1.55 ± 0.12 μM and 1.77 ± 0.24 μM concentration, respectively. No significant systemic toxicities were observed with HH044 treatments either given via i.p. injection or orally. Further in vivo studies combining nNOS inhibitors with immune checkpoint blockade are currently underway. Conclusions: HH044, as the first-in-class nNOS inhibitor, exhibits potent anti-melanoma activity by oral administration. Developing selective nNOS inhibitors has shown to be a novel therapeutic strategy to improve melanoma treatment. Citation Format: Anika Patel, Shirley Tong, Richard B. Silverman, Sun Yang. Development of HH044, an orally bioavailable nNOS inhibitor, for the treatment of cutaneous melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5938.

Immunogenicity and Loss of Effectiveness of Biologic Therapy for Inflammatory Bowel Disease Patients Due to Anti-Drug Antibody Development.

Many patients with inflammatory bowel disease (IBD) experience a loss of effectiveness to biologic therapy (i.e., anti-TNF therapy, etc.). Therefore, in addition to the adverse effects of the treatment, these patients also face failure to achieve and maintain remission. Immunogenicity, the process of production of antibodies to biological agents, is fundamental to the evolution of loss of response to treatment in IBD patients. The presence of these antibodies in patients is linked to decreased serum drug levels and inhibited biological activity. However, immunogenicity rates exhibit significant variability across inflammatory disease states, immunoassay formats, and time periods. In this review, we aimed to elucidate the immunogenicity and immune mechanisms of antibody formation to biologics, the loss of therapy response, clinical results of biological treatment for IBD from systematic reviews and meta-analyses, as well as to summarize the most recent strategies for overcoming immunogenicity and approaches for managing treatment failure in IBD.

Assessment of the effectiveness of weight-adjusted antibiotic administration, for reduced duration, in surgical prophylaxis of primary hip and knee arthroplasty.

Prophylactic antibiotics have significantly led to a reduction in the risk of post-operative surgical site infections (SSI) in orthopaedic surgery. The aim of using antibiotics for this purpose is to achieve serum and tissue drug levels that exceed, for the duration of the operation, the minimum inhibitory concentration of the likely organisms that are encountered. Prophylactic antibiotics reduce the rate of SSIs in lower limb arthroplasty from between 4% and 8% to between 1% and 3%. Controversy, however, still surrounds the optimal frequency and dosing of antibiotic administration. To evaluate the impact of introduction of a weight-adjusted antibiotic prophylaxis regime, combined with a reduction in the duration of administration of post-operative antibiotics on SSI incidence during the 2 years following primary elective total hip and knee arthroplasty. Following ethical approval, patients undergoing primary total hip arthroplasty (THA)/total knee arthroplasty (TKA) with the old regime (OR) of a preoperative dose [cefazolin 2 g intravenously (IV)], and two subsequent doses (2 h and 8 h), were compared to those after a change to a new regime (NR) of a weight-adjusted preoperative dose (cefazolin 2 g IV for patients < 120 kg; cefazolin 3g IV for patients > 120 kg) and a post-operative dose at 2 h. The primary outcome in both groups was SSI rates during the 2 years post-operatively. A total of n = 1273 operations (THA n = 534, TKA n = 739) were performed in n = 1264 patients. There was no statistically significant difference in the rate of deep (OR 0.74% (5/675) vs NR 0.50% (3/598); fishers exact test P = 0.72), nor superficial SSIs (OR 2.07% (14/675) vs NR 1.50% (9/598); chi-squared test P = 0.44) at 2 years post-operatively. With propensity score weighting and an interrupted time series analysis, there was also no difference in SSI rates between both groups [RR 0.88 (95%CI 0.61 to 1.30) P = 0.46]. A weight-adjusted regime, with a reduction in number of post-operative doses had no adverse impact on SSI incidence in this population.

A257 EARLY PROACTIVE THERAPEUTIC DRUG MONITORING WITH USTEKINUMAB THERAPY IN PAEDIATRIC CROHN’S DISEASE

Abstract Background Ustekinumab (UST) is an effective therapy for adults with moderate to severe Crohn’s disease (CD), but data concerning optimal dosing in children are sparse. Aims To examine real-world post-induction PK and efficacy in a prospective multicentre cohort study of paediatric CD (Canadian Children IBD Network (CIDsCaNN)). Methods Children 2-17 years-old with CD were eligible for this analysis if they received IV UST for treatment of luminal CD and had serum UST levels measured at week 8. Median with interquartile range (IQR) UST dose and serum trough levels at weeks 8 and 16 were compared between children ampersand:003C40 kg and ≥40 kg with Mann-Whitney U test. Clinical remission was defined as weighted Pediatric CD Activity Index (wPCDAI) ampersand:003C12.5. UST durability was compared between those with a week 8 serum UST level ampersand:003C5 versus ≥5 µg/mL (log-rank p-value). Results Between 21/04/2017 and 30/04/2023, 39 children were eligible (74% M; median age 13.5 (IQR 11.9-15.6) y; median weight 44.7 (IQR 30.4-55.0) kg, 12 children ampersand:003C40 kg; 84% bio-naïve). Median disease duration at UST start was 4 (IQR 1-17) months; CD location distal ileal ± limited cecal (18%), colonic (26%), ileocolonic (54%). Median follow-up duration was 10.0 (IQR 6.7-12.7) months. All children received UST IV induction (67% 260 mg, 18% 390 mg) followed by 90 mg SC every 8 weeks. Induction doses in mg per kg were higher in those ampersand:003C40 kg (median 9.11 (IQR 8.68-10.08)) compared to those ≥40 kg (5.77 (IQR 5.24-6.45) mg/kg), pampersand:003C0.001. Induction doses in mg per body surface area (BSA) in m2 were similarly higher in those ampersand:003C40 kg (median 251.66 (IQR 244.16-258.99) versus 195.15 (IQR 172.71-224.11) mg/m2, pampersand:003C0.001). Despite higher induction doses, week 8 trough levels were numerically lower in those ampersand:003C40 kg (median 4.32 (IQR 1.33-8.36) versus 6.96 (IQR 5.38-8.90) µg/mL, p=0.29). Week 16 serum UST levels were also numerically lower in ampersand:003C40 kg versus ≥40 kg (median 4.04 (IQR 1.92-6.98) versus 5.50 (IQR 3.17-8.27) µg/mL, p=0.57). Interval shortening during maintenance to every 4 weeks occurred in 7 children prior to week 16, and in 14 children prior to 6 months. By 4 months, 19 of 33 children with available data (56%) achieved clinical remission. Overall, 8/39 (21%) ceased UST. Those who discontinued UST had significantly lower week 8 levels than those who continued UST (median 3.52 (IQR 1.19-6.12) versus 7.15 (IQR 5.09-10.15) µg/mL, p=0.027). In survival analysis, week 8 trough level ampersand:003C5 µg/mL was associated with an increased risk of UST discontinuation (log-rank p=0.032) (Figure 1). Conclusions Higher UST concentration at week 8 is associated with greater drug durability. A higher BSA-based induction for children ampersand:003C40 kg is supported by higher serum drug levels and improved drug durability. Figure 1. Ustekinumab durability by week 8 serum drug level Funding Agencies CIHR

P674 Real-world experiences of switching to subcutaneous formulation in IBD patients on maintenance vedolizumab treatment

Abstract Background Usability of subcutaneous vedolizumab (SC VDZ) in inflammatory bowel diseases (IBD, ulcerative colitis [UC], Crohn’s disease [CD]) have proved via clinical trials, while real-world data collection is ongoing. Experiences of Central-European population and assessment of patient’s perspectives are lacking. Our study aimed to evaluate the real-world efficacy, safety and patient’s preferences of SC VDZ maintenance treatment after switching from intravenous (IV) formulation in a Hungarian IBD cohort. Methods In this prospective, multicenter cohort study, IBD patients on maintenance IV VDZ treatment were enrolled, who switched to SC administration. Baseline was the day of the switch, while 52-week follow-up was set. Clinical and demographic data were collected, while serum VDZ level and CRP was measured at baseline and at w52. A non-validated questionary was filled by patients who were on drug at w12 recording patient’ satisfaction. Primary outcome was the drug survival rate at one year, while secondary outcomes were change in corticosteroid-free clinical (CSFR, based on physicians’ global assessment score PGA &amp;lt; 1), and biochemical remission (BR, 5 mg/l &amp;gt; CRP) rates to w52, safety issues and patients’ preferences and change in serum drug levels. Results In total, 37 IBD patients were followed (Table 1., 15 CD and 22 UC, male/female ratio 45.9 %, median age 42.0 [IQR 34-49] years). In CD group, 66.7 % were in CSFR and 60 % in BR, while in UC group 63.6 % were in CSFR and 68.2 % in BR (p = 0.55 and p = 0.61). Overall, 29.7 % of patients ceased SC VDZ treatment after a median of 20 (IQR 6-26) weeks. Cessation was due to secondary response losing in 3/6 and 4/5 patients in CD and UC group. In case of 2 and one patients, SC treatment was terminated due to local reactions. One patient was fear of needle. Severe adverse event did not occur. Factors associated with discontinuation did not identify. The mean serum VDZ level has higher at w52 compared to baseline in CD and UC patients (CD: 8.9 ± 6.9 to 30.6 ± 17.8 ug/mL, p = 0.047; UC: 13.6 ± 13.8 to 33.6 ± 17.6 ug/mL, p = 0.001, Figure 1.), while disease activity was stable. 84 % of the patients who filled the questionnaire were satisfied with injection, while only one patient found it difficult to inject. Conclusion Transition from IV to SC maintenance VDZ treatment is effective at one year, the overall survival rate is high presumably due to the elevated serum drug levels. Severe safety issue did not raise. Satisfaction of switched patients is high, which may improve treatment adherence and save resources.