Optimal Drug Exposure Research Articles

208. Exposure-response relationship of ceftazidime/avibactam in adults with central nervous system infections caused by carbapenem-resistant Klebsiella pneumoniae: a prospective observational study

Abstract Background Central nervous system (CNS) infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) poses significant challenges for clinicians in ICU. Achieving optimal drug exposure in the cerebrospinal fluid (CSF) is crucial for good outcomes. This study aimed to evaluate the exposure-response relationship of ceftazidime/avibactam (CZA) in plasma and CSF. Methods All patients received CZA (2.5 g), IV infusion (over 2 hours), q8h. At steady-state after the fourth dose of CZA, the concentrations of CZA in the plasma and CSF were determined by ultra-performance liquid chromatography (UPLC) at 1, 2, 2.25, 2.5, 3, 4, 6, and 8 h post-dose. The PK/PD index of ceftazidime (CAZ) and avibactam(AVI) was calculated for each patient. Demographic, clinical efficacy, microbiological eradication, and 28-day mortality were reviewed. Blood and CSF samples were collected for calculation of PK parameters by non-compartmental pharmacokinetics (PK) modeling. The attainment of CAZ and AVI PK/PD targets in plasma and CSF was calculated to assess the exposure-response relationship of CZA and the corresponding clinical efficacy rate and bacterial eradication rate. Results CAZ and AVI demonstrated good penetration into CSF, evidenced by median CSF/plasma AUCtau ratio of 43.8 % and 55.8 %, respectively. CZA 2.5 g q8h achieved CAZ PK/PD target of 50%fT >MIC in both plasma and 50%T >MIC in CSF of all patients and reached AVI PK/PD target of 50%T >CT=1 mg/L in CSF of 80% (16/20) of patients. The dosing regimen also achieved CAZ PK/PD target of 100% fT >4MIC in plasma of 9 patients and 100% T >4MIC in CSF of 14 patients. At the end of the treatment, the overall clinical and microbiological efficacy rates were 80.0% and 100%, respectively. Only one case of CZA-related adverse event (Clostridioides difficile-associated diarrhoea) was reported. Conclusion The good CSF penetration of CZA enables the dosing regimen of CZA 2.5 g q8h a promising treatment option for CNS infections caused by CRKP. Disclosures Nanyang Li, Master of Medicine, TenNor Therapeutics (Suzhou) Ltd: Investigator Jing Zhang, Doctor of Medicine, TenNor Therapeutics (Suzhou) Ltd: Investigator

Advances in the Repurposing and Blood–Brain Barrier Penetrance of Drugs in Pediatric Brain Tumors

Central nervous system (CNS) tumors are the leading cause of cancer-related mortality in children, with prognosis remaining dismal for some of these malignancies. Though the past two decades have seen advancements in surgery, radiation, and targeted therapy, major unresolved hurdles continue to undermine the therapeutic efficacy. These include challenges in suboptimal drug delivery through the blood–brain barrier (BBB), marked intra-tumoral molecular heterogeneity, and the elusive tumor microenvironment. Drug repurposing or re-tasking FDA-approved drugs with evidence of penetration into the CNS, using newer methods of intracranial drug delivery facilitating optimal drug exposure, has been an area of intense research. This could be a valuable tool, as most of these agents have already gone through the lengthy process of drug development and the evaluation of safety risks and the optimal pharmacokinetic profile. They can now be used and tested in clinics with an accelerated and different approach. Conclusions: The next-generation therapeutic strategy should prioritize repurposing oncologic and non-oncologic drugs that have been used for other indication, and have demonstrated robust preclinical activity against pediatric brain tumors. In combination with novel drug delivery techniques, these drugs could hold significant therapeutic promise in pediatric neurooncology.

Lateral flow test versus enzyme-linked immunosorbent assay to measure infliximab trough concentrations: A head-to-head comparison.

Infliximab is an antitumour necrosis factor agent used to treat inflammatory bowel disease (IBD). Measurement of infliximab trough concentrations (C-troughs) are used to optimize drug exposure and improve outcomes. Currently, enzyme-linked immunosorbent assays (ELISAs) are used predominantly for this purpose. Novel lateral flow immunoassays provide a rapid result. We collected 100 paired serum samples of adolescents and young adults with IBD, who were treated with infliximab maintenance infusions. C-troughs were measured with the Quantum Blue® lateral flow test (QB) with ELISA. Results were categorized as low-range (mean C-trough ≤5 µg/mL) or high-range (>5 µg/mL). A Bland-Altman plot was created with limits of clinical acceptability set at ≤2 µg/mL for low-range and ≤40% for high-range C-troughs. A concordance matrix was created to evaluate the C-trough-based clinical scenario (whether or not to escalate infliximab) using a cutoff value of 5 µg/mL. Agreement between QB and ELISA was good (intraclass correlation coefficient: 0.85). In the low-range, 90% (95% confidence interval [CI]: 79-96) of measurements were within the limits of clinical acceptability. In the high-range this was 67% (95% CI: 53-79). QB provided higher results than ELISA. The concordance matrix showed 81% agreement (95% CI: 72-88, κ: 0.62). Lateral flow- and ELISA-based infliximab C-trough measurements were in agreement. The swift establishment of infliximab C-troughs matters for patients experiencing increased disease activity. In the event of a low C-trough, prompt dose escalation can be initiated.

Integration of genomic and pharmacokinetic data to predict clinical outcomes in HIV-associated cryptococcal meningitis.

HIV-associated cryptococcal meningitis is associated with a high burden of mortality. Research into the different strain types causing this disease has yielded inconsistent findings in terms of which strains are associated with worse clinical outcomes. Our study suggests that the exposure of patients to potent anti-cryptococcal drugs has a more significant impact on clinical outcomes than the strain type of the infecting organism. Future research should focus on optimizing drug exposure, particularly in the context of novel anticryptococcal drugs coming into clinical use.

Drug Exposure and Treatment Outcomes in Patients With Multidrug-Resistant Tuberculosis and Diabetes Mellitus: A Multicenter Prospective Cohort Study From China.

The management of multidrug-resistant tuberculosis (MDR-TB) remains challenging. Treatment outcome is influenced by multiple factors; the specific roles of diabetes and glycemic control remain uncertain. This study aims to assess the impact of glycemic control on drug exposure, to investigate the association between drug exposure and treatment outcomes, and to identify clinically significant thresholds predictive of treatment outcome, among patients with diabetes. This multicenter prospective cohort study involved patients with confirmed MDR-TB and diabetes. Drug exposure level was estimated by noncompartmental analysis. The minimum inhibitory concentrations (MICs) were determined for the individual Mycobacterium tuberculosis isolates. The influence of poor glycemic control (glycated hemoglobin ≥7%) on drug exposure and the associations between drug exposure and treatment outcome were evaluated by univariate and multivariate analysis. Classification and regression tree analysis was used to identify the drug exposure/susceptibility thresholds. Among the 131 diabetic participants, 43 (32.8%) exhibited poor glycemic control. Poor glycemic control was independently associated with decreased exposure to moxifloxacin, linezolid, bedaquiline, and cycloserine, but not clofazimine. Additionally, a higher ratio of drug exposure to susceptibility was found to be associated with a favorable MDR-TB treatment outcome. Thresholds predictive of 6-month culture conversion and favorable outcome were bedaquiline area under the concentration-time curve (AUC)/MIC ≥245 and moxifloxacin AUC/MIC ≥67, demonstrating predictive accuracy in patients, regardless of their glycemic control status. Glycemic control and optimal TB drug exposure are associated with improved treatment outcomes. This dual management strategy should be further validated in randomized controlled trials of patients with MDR-TB and diabetes.

Association between escitalopram dose personalisation based on quantification of drug plasma levels and the outcome of escitalopram treatment

IntroductionGiven the negative impact of anxiety and depression on society and the shortage of new antidepressants, it is of paramount importance to make the best use of available treatment options. Therapeutic drug monitoring (TDM) in escitalopram treatment can potentially be clinically useful, as underexposed patients show reduced efficacy of escitalopram treatment and as adverse drug reactions (ADRs) of escitalopram are dose-dependent.ObjectivesThis prospective cohort study aimed to investigate whether escitalopram treatment efficacy or safety are associated with escitalopram dose adjustment based on TDM readouts.Methods89 included patients aged between 15 and 65 years who suffered from depression were enrolled in the study before starting treatment with escitalopram. Patients were assessed one day before starting treatment with the recommended dose of 10 mg/day escitalopram (baseline, visit 0) and at follow-up after four and eight weeks. Dose adjustment at four-week follow-up was based on the measured escitalopram plasma level two weeks after treatment initiation; patients who required dose increase to 15 or 20 mg/day comprised comparator group, patients who did not required dose increase comprised control group, while patients who did not reach optimal exposure at eight-week follow-up were characterized as non-compliers. Treatment efficacy was approximated by the relative change on the Hamilton Depression Rating Scale (HAMD), while safety was approximated based on the changes on the Scandinavian UKU side effect rating scale and ECG readouts. Changes in HAMD, UKU score and QTc interval were compared between groups by one-way ANOVA or chi-square tests.ResultsCompared to baseline, significant reductions in HAMD scores of 36% (95%CI, 30%-43%) and 53% (95%CI, 47%-60%) were observed at four- and eight-week follow-up, respectively; however, there were no significant differences between groups (p > 0.1). In the groups adjusted to 15 and 20 mg, 15/26 and 19/33 patients, respectively, reported adverse effects, compared with 6/17 patients in the control group and 6/13 in the non-complier group (p>0.1). A significant mean QTc prolongation of 6.40 ms (95%CI, 3.27-9.53) was observed between the baseline and eight-week follow-up (p=0.0013), without significant differences in QTc interval prolongation between groups (p > 0.1).ConclusionsEscitalopram dose adjustment resulted in optimal drug exposure and solid treatment response in the majority of patients; however, no differences in efficacy were found between the patients who required dose adjustments, the ones who did not, and the ones who ultimately did not achieve optimal exposure. In addition, the selective increase of the dose to the patients who did not reach optimal drug exposure on the recommended dose of 10 mg/day did not lead to significant increase in adverse drug reactions and QTc prolongation.Disclosure of InterestNone Declared

Precise infliximab exposure and pharmacodynamic control to achieve deep remission in paediatric Crohn’s disease (REMODEL-CD): study protocol for a multicentre, open-label, pragmatic clinical trial in the USA

IntroductionThe only biologic therapy currently approved to treat moderate to severe Crohn’s disease in children (<18 years old) are those that antagonise tumour necrosis factor-alpha (anti-TNF). Therefore, it is critically...

Toxicities of Novel Agents for the Treatment of Advanced Bladder Cancer

Enfortumab vedotin and erdafitinib have specific toxicities that need careful management in order to optimise drug exposure while maintaining patients' quality of life. Patient education, meticulous monitoring, and a multidisciplinary approach are key to optimising outcomes so that patients can reap the benefits of these new treatments.

Microfluidics-derived hierarchical microparticles for the delivery of dienogest for localized endometriosis therapy

Drug therapy is one of the most important strategies for treating gynecological diseases. Local drug delivery is promising for achieving optimal regional drug exposure, considering the complex anatomy and dynamic environment of the upper genital tract. Here, we present microparticle-based microcarriers with a hierarchical structure for localized dienogest (DNG) delivery and endometriosis treatment. The microparticles were fabricated by microfluidics and consisted of photo-crosslinked bovine serum albumin hydrogel particles (D@P-B MPs) encapsulating DNG-loaded PLGA (poly lactic-co-glycolic acid) microspheres. Such design enables the microparticles to have sustained release capacity and cell adhesion ability. Based on this, the microparticles were applied for the treatment of peritoneal endometriosis through intraperitoneal injection. The performance of the microparticles in inhibiting the growth of ectopic lesions as well as their anti-inflammatory, anti-angiogenesis, and pelvic pain-relieving effects are well demonstrated in vivo. These findings indicate that the present hierarchical microparticles are good candidates for localized treatment of endometriosis and are promising for the management of gynecological diseases. STATEMENT OF SIGNIFICANCE: We prepared photo-crosslinked bovine serum albumin hydrogel particles (D@P-B MPs) encapsulating DNG-loaded PLGA microspheres using microfluidic electrospray. Such hierarchical structure provided multiple functions of the particles as drug carriers. The hierarchical microparticles not only supported the sustained release of drugs but also provided adhesion to human ectopic endometrial stromal cells. The hierarchical microparticles represented a localized treatment method for endometriosis and is promising for the management of gynecological diseases.

Advanced Body Measurement Techniques Can Complement Current Methods of Cytotoxic Chemotherapy Dose Prescription

Within chemotherapy, estimates of a patient’s body surface area (BSA) are used to calculate drug dosages. However, the use of BSA for calculating chemotherapy dosage has been heavily criticised in previous literature, with potentially significant implications for the effectiveness and toxicity of treatment. BSA has been found to be a poor indicator of optimal drug exposure that does not account for the complex processes of cytotoxic drug distribution and elimination. In addition, differences in BSA estimates between existing formulae have been shown to be so large that they can affect patients’ mortality, particularly in patients with atypical body types. This uncertainty associated with BSA prediction may decrease the confidence of practitioners when determining chemotherapy dosages, particularly with regards to the risk of excess toxicity from over-dosing, or a reduced anti-cancer effect due to under-dosing. The use of national dose-banding in the UK may in some cases account for possible inaccuracies, but the threshold of variance in this case is small (+/−6%). Advanced body measurement techniques, utilising digital tools such as three-dimensional (3D) surface imaging, capture accurate external dimensions and detailed shape characteristics of the human body. Measures of body shape describe morphological variations that cannot be identified by traditional anthropometric techniques and improve the prediction of total body fat and distribution. It is our view that the use of advanced body measurement techniques can provide practitioners with tools for prescribing chemotherapy dosages that are valid for individuals, regardless of their body type.

Real-Time Monitoring of Antibiotics in the Critically Ill Using Biosensors.

By ensuring optimal dosing, therapeutic drug monitoring (TDM) improves outcomes in critically ill patients by maximizing effectiveness while minimizing toxicity. Current methods for measuring plasma drug concentrations, however, can be challenging, time-consuming, and slow to return an answer, limiting the extent to which TDM is used to optimize drug exposure. A potentially promising solution to this dilemma is provided by biosensors, molecular sensing devices that employ biorecognition elements to recognize and quantify their target molecules rapidly and in a single step. This paper reviews the current state of the art for biosensors regarding their application to TDM of antibiotics in the critically ill, both as ex vivo point-of-care devices supporting single timepoint measurements and in vivo devices supporting continuous real-time monitoring in situ in the body. This paper also discusses the clinical development of biosensors for TDM, including regulatory challenges and the need for standardized performance evaluation. We conclude by arguing that, through precise and real-time monitoring of antibiotics, the application of biosensors in TDM holds great promise for enhancing the optimization of drug exposure in critically ill patients, offering the potential for improved outcomes.

Drug-drug interactions between propofol and ART drugs: Inhibiting neuronal activity by affecting glucose metabolism.

The use of two or more drugs carries the potential risk of drug-drug interactions (DDIs), which may result in adverse reactions. Some human immunodeficiency virus (HIV)-infected patients who receive antiretroviral therapy (ART) may require general anesthesia with propofol (PRL) before undergoing surgical treatment. Both PRL and ART drugs may lead to neuronal dysfunction, which can be accompanied by energy metabolism disorders. Neurons take in glucose mainly through glucose transporter 3 (Glut3) which is specifically expressed on the cell membranes of neurons. However, to date, no study has examined whether the DDIs of PRL and ART drugs interfere with glucose metabolism and Glut3 expression in neurons. An in vitro model was constructed using the primary cultures of neurons. PRL and ART drugs (EFV, AZT, and 3TC), were added at different concentrations (low, medium, and high). The neurons were exposed to the drugs for 1, 4, 8, and 12 h. The optimal drug concentration and exposure time were selected. The cellular survival rate, glucose concentration, electrophysiology, and the expression of Glut3 were detected. There were no significant changes in the cellular survival rates of the neurons that were exposed to both PRL and ART drugs at low concentrations for 1 h. However, the survival rates of the neurons decreased significantly as the drug concentrations and durations increased. The glucose concentration of the neurons that were exposed to both PRL and the ART drugs was significantly decreased. The glucose concentration of the neurons was not affected by any individual drug. The amplitude of the action potential and the expression of Glut3 were decreased in the neurons that were exposed to both PRL and ART drugs. The main adverse reactions induced by the DDIs between PRL and the ART drugs were decreased glucose metabolism and neuronal damage, which were caused by inhibiting the expression of Glut3. More importantly, we found that decreases in glucose metabolism predated neuronal damage.

Abstract LB219: Inducing significant and efficient tumor growth inhibition vs trastuzumab deruxtecan with low drug-load topoisomerase 1 inhibitor ADC using novel peptide linkers for payload conjugation

Abstract The Araris’ site-specific and one-step linker conjugation technology aims at generating stable, safe and highly potent ADCs without the need for antibody engineering prior to payload conjugation. Here, we generated an anti-HER2 ADC using a Topoisomerase 1 (Topo1) inhibitor as payload with highly favorable biophysical properties and superior anti-tumor efficacy compared to Trastuzumab deruxtecan in head-to-head in vitro and in vivo studies. Based on trastuzumab as the targeting antibody and a Topoisimerase 1 inhibitor as payload, we generated highly homogeneous and pure ADCs with a drug-to antibody-ratio (DAR) of 2. In in-vitro assays on target positive cell-lines, the Araris Topo 1 ADC demonstrated potent cell-cytotoxicity in the low nM-range similar to the approved Trastuzumab deruxtecan which has a DAR of 8. Moreover, the ADC showed excellent stability in mouse, cynomolgus and human sera exemplified by the absence of payload deconjugation or linker cleavage while Trastuzumab deruxtecan showed significant payload loss during the 14d incubation period. Interestingly, despite the improved stability, the kinetics for payload release was highly efficient in human Cathepsin B or human liver-lysosome (HLL) enzyme cleavage assays. Most importantly, the ADC was extremely stable in circulation as shown in pharmacokinetic studies in rodents, demonstrating an exposure profile similar to the unmodified trastuzumab parent antibody. In efficacy studies using an established NCI-N87 colon cancer model (therapeutic setting), a single injection of the Araris Topo 1 ADC at DAR2 at a dose of 52ug/kg (adjusted payload dose) induced superior anti-tumor activity compared to Trastuzumab deruxtecan at DAR of 8, injected at the same payload dose. Complete tumor regression of all tumors (7/7) was obtained at 104ug/kg payload dose and lasted throughout the whole study duration (total 80 days) and was very well tolerated. The data show that Araris Topo 1 ADCs assembled using novel peptide linkers, even at a DAR of as low as 2 have a very efficient anti-tumor activity suggesting optimal drug exposure, targeting and release of the payload. In summary, we show that the Araris Topo1 linker-payloads result in highly potent ADCs with very favorable biophysical properties and extremely efficient payload release as well as an antibody-like exposure profile making them ideal linker-payloads for solid tumor targeting. We anticipate the low-drug load to be favorable in avoiding excessive toxicities in non-targeted tissues. Finally, the Araris bioconjugation technology allows for the generation of tailor-made ADC candidates with improved therapeutic indices. Citation Format: Isabella Attinger-Toller, Rachael Fay, Romain Bertrand, Philipp Probst, Ramona Stark, Roger Santimaria, Dragan Grabulovski, Bernd Schlereth, Philipp Rene Spycher. Inducing significant and efficient tumor growth inhibition vs trastuzumab deruxtecan with low drug-load topoisomerase 1 inhibitor ADC using novel peptide linkers for payload conjugation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB219.

Noninvasive testing for mycophenolate exposure in children with renal transplant using urinary metabolomics.

Despite the common use of mycophenolate in pediatric renal transplantation, lack of effective therapeuic drug monitoring increases uncertainty over optimal drug exposure and risk for adverse reactions. This study aims to develop a novel urine test to estimate MPA exposure based using metabolomics. Urine samples obtained on the same day of MPA pharmacokinetic testing from two prospective cohorts of pediatric kidney transplant recipients were assayed for 133 unique metabolites by mass spectrometry. Partial least squares (PLS) discriminate analysis was used to develop a top 10 urinary metabolite classifier that estimates MPA exposure. An independent cohort was used to test pharmacodynamic validity for allograft inflammation (urinary CXCL10 levels) and eGFR ratio (12mo/1mo eGFR) at 1 year. Fifty-two urine samples from separate children (36.5% female, 12.0± 5.3 years at transplant) were evaluated at 1.6± 2.5 years post-transplant. Using all detected metabolites (n= 90), the classifier exhibited strong association with MPA AUC by principal component regression (r= 0.56, p< .001) and PLS (r= 0.75, p< .001). A practical classifier (top 10 metabolites; r= 0.64, p< .001) retained similar accuracy after cross-validation (LOOCV; r= 0.52, p< .001). When applied to an independent cohort (n= 97 patients, 1053 samples), estimated mean MPA exposure over Year 1 was inversely associated with mean urinary CXCL10:Cr (r= -0.28, 95% CI -0.45, -0.08) and exhibited a trend for association with eGFR ratio (r= 0.35, p= .07), over the same time period. This urinary metabolite classifier can estimate MPA exposure and correlates with allograft inflammation. Future studies with larger samples are required to validate and evaluate its clinical application.

872. Voriconazole Therapeutic Drug Monitoring (TDM): How Common is Autoinduction?

Abstract Background Therapeutic drug monitor (TDM) guided optimized dosing of Voriconazole allows optimal drug exposure in the management of mold infection (MI). In addition to already known nuances in pharmacokinetics such as CYP2C19 genetic polymorphism and the role of drug interactions both necessitating TDM, case reports have suggested that auto-induction may occur after initially achieving a therapeutic level. We assessed whether the levels of Voriconazole can change over time and become subtherapeutic due to auto-induction. Methods We prospectively enrolled, adults ≥ 18 y.o of age, on Voriconazole for the treatment of MI at the University Of Alberta Hospital. After achieving an initial therapeutic margin, (1–5.5mg/l), we monitored Voriconazole levels twice a month, using high-performance liquid chromatography, until discontinuation or at 12 weeks of therapy. We calculated the incidence of Voriconazole sub-therapeutic concentrations (auto-induction) defined as drop of Voriconazole level below one, with previous concentrations between the therapeutic margins of 1–5.5 mg/L. Adjustment of Voriconazole dosing in case of auto-induction was at the discretion of the treating physician. The excess Voriconazole dose adjustment was calculated in patients where dosing was increased. Results Between January 2021 and April 2022, we enrolled 12 patients. Median age (IQR) was 62 (52–73), and 25 % were female. Patient characteristics are in table 1. Auto-induction was observed in 6/10 (60%) who completed 12 weeks follow up blood work. Median time to auto-induction was of 46 days (39–55). Voriconazole dosing was increased in 4/6 patients with auto-induction. Of the four patients with dose adjustment, the cumulative Voriconazole dose was 13% higher than expected, which correspond to 5,300 mg excess Voriconazole per patient to maintain therapeutic levels. Conclusion Auto-induction is common in patients treated with Voriconazole. Future studies are needed to assess if undetected auto-induction affects outcomes. Funding: AVIR Pharma. Disclosures Carlos Cervera, Associate Professor, Astra-Zeneca: Advisor/Consultant|AVIR Pharma: Grant/Research Support|AVIR Pharma: Honoraria|Lilly: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Honoraria|Sunovion: Advisor/Consultant|Takeda: Advisor/Consultant|Takeda: Honoraria|VerityPharma: Advisor/Consultant Dima Kabbani, MD, MSc, AVIR Pharma: Grant/Research Support|AVIR Pharma: Honoraria|GSK: Honoraria|Merck: Grant/Research Support.

1282. Safety, Tolerability, and Pharmacokinetics of BRII-732, A Medoxomil Carbonate Prodrug of Islatravir in Healthy Adult Subjects

Abstract Background BRII-732, a prodrug of islatravir (ISL), is a potent HIV-1 nucleotide reverse transcriptase translocation inhibitor. Following oral absorption, BRII-732 is rapidly converted to ISL, which is metabolized intracellularly to the active metabolite, ISL triphosphate (ISL-TP). Single doses of ISL as low as 0.5 mg significantly suppressed HIV-1 RNA by more than 1.0 log at day 7 in treatment-naive adults with HIV-1 infection. Current development work with BRII-732 is designed to provide optimal drug exposure to enable once weekly (QW) dosing, to be part of combination antiretroviral therapy to provide improved patient convenience and treatment adherence. Methods This was a Phase 1, randomized, double-blind, placebo-controlled study consisting of healthy adult subjects enrolled in five single ascending dose and two multiple ascending dose cohorts. The objectives of the study were to assess the safety, tolerability, and PK profiles of BRII-732 and ISL in plasma; ISL-DP and ISL-TP in human PBMCs. BRII-732 was orally administered in the fasted state using an oral solution formulation. Safety-related assessments included physical examinations, ECGs, vital signs, AEs, and standard clinical laboratory tests. Results BRII-732 as single dose or multiple doses was generally safe and well-tolerated when administered to healthy adult subjects. There were no Grade ≥ 3 AEs, SAEs, drug-related AEs leading to withdrawal or graded lymphocyte abnormalities. BRII-732 rapidly converted to ISL post BRII-732 oral administration with no detectable level (LLOQ = 1.0 ng/mL) of BRII-732 in systemic circulation at 0.5h. Dose proportional ISL exposure increases were observed over the dose range of 10 mg to 200 mg of BRII-732. No meaningful ISL accumulation in plasma was observed after 3 QW BRII-732 doses. ISL-DP and ISL-TP exposures in PBMC cells increased dose-dependently. Approximately 1.7-2.0 fold accumulation ratios for ISL-DP and ISL-TP are consistent with observed long terminal half-lives of 110-150 hours. Conclusion Safety, tolerability and PK profiles including ISL in plasma and ISL-TP in PBMC cells after single and multiple oral administrations of BRII-732 supports further development of BRII-732 as part of oral weekly combination antiretroviral therapy. Disclosures David A. Margolis, MD MPH, Brii Biosciences: Stocks/Bonds Ji Ma, PhD, Brii Biosciences: Stocks/Bonds Michael Watkins, PharmD, Brii Biosciences: Stocks/Bonds Yujin Wang, M.Sc., Brii Biosciences: Stocks/Bonds Chetana Trivedi, B.A., Brii Biosciences: Stocks/Bonds Chi-Chi Peng, PhD, Brii Biosciences: Stocks/Bonds Xuelian Wei, PhD, Brii Biosciences: Stocks/Bonds Lijie Zhong, PhD, Brii Biosciences: Stocks/Bonds Kamlesh Patel, PhD, Brii Biosciences: Stocks/Bonds Jean-Luc Girardet, PhD, Brii Biosciences: Stocks/Bonds Michael Wang, PhD MBA, Brii Biosciences: Stocks/Bonds Annalise VonderEmbse, PhD, Brii Biosciences: Stocks/Bonds Li Yan, MD PhD, Brii Biosciences: Stocks/Bonds Zhi Hong, PhD, Brii Biosciences: Ownership Interest Lianhong Xu, PhD, Brii Biosciences: Stocks/Bonds.

The impact of enteral feeding and therapeutic monitoring of rifampicin with dose escalation in critically ill patients with tuberculosis

ObjectivesCritically ill patients with tuberculosis (TB) face a high mortality risk and require effective treatment. There is a paucity of data on rifampicin pharmacokinetics, the impact of continuous enteral feeding on drug absorption, and the potential of therapeutic drug monitoring (TDM) to optimize drug exposure in these patients. MethodsWe performed a sequential pharmacokinetic study to determine the impact of feeding and TDM with rifampicin dose escalation in critically ill patients with TB. Noncompartmental pharmacokinetic analysis was performed. ResultsAmong 20 critically ill patients (40% were HIV-infected), median rifampicin Cmax (maximum serum concentration) in the fasted and fed states were 5.1 µg/ml versus 3.3 µg/ml, respectively (P <0.0001; geometric mean ratio 1.95; 90% confidence interval 1.46-2.60). The proportion of patients with low rifampicin concentrations in the fasted and fed states was 80% vs 100% (P-value = 0.1336). Optimized dosing led to a per-patient median rifampicin dosing of 24.6 mg/kg and a median Cmax increase from 2.4 µg/ml to 17.8 µg/ml (P-value = 0.0005; geometric mean ratio 8.29; 90% confidence interval 3.88-17.74). TDM-guided dose escalation increased the proportion of patients achieving the suggested target rifampicin concentration compared with standard dosing (83% vs 0%, P-value = 0.004). ConclusionWe found low rifampicin concentrations in all patients receiving continuous enteral feeding. TDM-guided dose escalation provided an effective strategy to achieve target drug exposure in these critically ill patients with TB.

Optimal ceftazidime/avibactam dosing exposure against KPC-producing Klebsiella pneumoniae.

Infections due to carbapenem-resistant Enterobacterales are considered urgent public health threats and often treated with a β-lactam/β-lactamase inhibitor combination. However, clinical treatment failure and resistance emergence have been attributed to inadequate dosing. We used a novel framework to provide insights of optimal dosing exposure of ceftazidime/avibactam. Seven clinical isolates of Klebsiella pneumoniae producing different KPC variants were examined. Ceftazidime susceptibility (MIC) was determined by broth dilution using escalating concentrations of avibactam. The observed MICs were characterized as response to avibactam concentrations using an inhibitory sigmoid Emax model. Using the best-fit parameter values, %fT&gt;MICi was estimated for various dosing regimens of ceftazidime/avibactam. A hollow-fibre infection model (HFIM) was subsequently used to ascertain the effectiveness of selected regimens over 120 h. The drug exposure threshold associated with bacterial suppression was identified by recursive partitioning. In all scenarios, ceftazidime MIC reductions were well characterized with increasing avibactam concentrations. In HFIM, bacterial regrowth over time correlated with emergence of resistance. Overall, suppression of bacterial regrowth was associated with %fT&gt;MICi ≥ 76.1% (100% versus 18.2%; P &lt; 0.001). Using our framework, the optimal drug exposure could be achieved with ceftazidime/avibactam 2.5 g every 12 h in 5 out of 7 isolates. Furthermore, ceftazidime/avibactam 2.5 g every 8 h can suppress an isolate deemed resistant based on conventional susceptibility testing method. An optimal drug exposure to suppress KPC-producing bacteria was identified. The novel framework is informative and may be used to guide optimal dosing of other β-lactam/β-lactamase inhibitor combinations. Further in vivo investigations are warranted.

Omadacycline Pharmacokinetics/Pharmacodynamics in the Hollow Fiber System Model and Potential Combination Regimen for Short Course Treatment of Mycobacterium kansasii Pulmonary Disease.

The 12-month therapy duration for the treatment of Mycobacterium kansasii pulmonary disease calls for more efficacious drugs for better treatment outcomes and to shorten the therapy duration. We performed (i) omadacycline MIC with M. kansasii ATCC 12478 strain and 21 clinical isolates, (ii) dose-response study in the hollow fiber system model of M. kansasii (HFS-Mkn) with six human equivalent omadacycline daily doses to determine the optimal drug exposure for the maximal kill, and (iii) a second HFS-Mkn study to determine the efficacy of omadacycline (300 mg/day) plus moxifloxacin (600 mg/day) plus tedizolid (200 mg/day) combination regimen with standard regimen as comparator. GraphPad Prism was used for data analysis and graphing. MIC of the reference strain was 4 mg/L but ranged from 8 to 32 mg/L among the 21 clinical isolates. In the HFS-Mkn, the exposure required for 50% of the maximal effect (EC50) was an omadacycline area under the concentration-time curve to MIC (AUC0-24/MIC) ratio of 1.95. The optimal exposure was an AUC0-24/MIC of 3.05, which could be achieved with 300 mg/day clinical dose. The omadacycline-moxifloxacin-tedizolid combination sterilized the HFS-Mkn in 14 days with a linear-regression based kill rate of -0.309 ± 0.044 log10 CFU/mL/day compared to the kill rate of -0.084 ± 0.036log10 CFU/mL/day with the standard regimen or 3.7-times faster. Omadacycline has efficacy against M. kansasii and could be used at 300 mg/day in combination with moxifloxacin and tedizolid for the treatment of M. kansasii pulmonary diseases with the potential to shorten the currently recommended 12-month therapy duration.

Personalized immunosuppression after kidney transplantation.

With advances in immunosuppressive therapy, there have been significant improvements in acute rejection rates and short-term allograft survival in kidney transplant recipients. However, this success has not been translated into long-term benefits by the same magnitude. Optimization of immunosuppression is important to improve the clinical outcome of transplant recipients. It is important to note that each patient has unique attributes and immunosuppression management should not be a one-size-fits-all approach. Elderly transplant patients are less likely to develop acute rejection but more likely to die from infectious and cardiovascular causes than younger patients. For those with post-transplant cancers and BK polyomavirus-associated nephropathy, reduction of immunosuppression can increase the risk of rejection. Therapeutic drug monitoring (TDM) is routinely used for dosage adjustment of several immunosuppressive drugs. It has been hoped that pharmacogenetics can be used to complement TDM in optimizing drug exposure. Among the various drug-genotype pairs being investigated, tacrolimus and CYP3A5 gives the most promising results. Different studies have consistently shown that CYP3A5 expressers require a higher tacrolimus dose and take longer time to achieve target blood tacrolimus levels than nonexpressers. However, for pharmacogenetics to be widely used clinically, further trials are necessary to demonstrate the clinical benefits of genotype-guided dosing such as reduction of rejection and drug-related toxicities. The development of different biomarkers in recent years may help to achieve true personalized therapy in transplant patients.