Terminal Phase Half-life Research Articles

MB09, a denosumab biosimilar candidate: Biosimilarity demonstration in a phase I study in healthy subjects.

This was a Phase I, randomized, double-blinded, three-arm, single-dose, parallel study aimed to demonstrate pharmacokinetic (PK) similarity between MB09 (a denosumab biosimilar candidate) and reference denosumab (XGEVA® from European Union [EU-reference] and United States [US-reference]) in a healthy male population. The primary PK endpoints included: Area under the serum concentration versus time curve from time 0 to the last quantifiable concentration timepoint (AUC0-last); and maximum observed serum concentration (Cmax). Secondary endpoints included: AUC from time 0 extrapolated to infinity (AUC0-∞), time to reach maximum observed concentration, clearance, terminal phase half-life, pharmacodynamic, safety, and immunogenicity assessments. A total of 255 subjects were randomized (1:1:1) to receive a subcutaneous 35 mg dose of MB09 or reference denosumab. Cmax was reached after denosumab administration, followed by a decline in the concentration with similar terminal phase half-live across treatment arms. Systemic exposure of MB09 (AUC0-last and Cmax) was equivalent to the reference denosumab, as the 90% confidence intervals around the geometric least square mean ratios laid within the predefined acceptance limits (80.00%, 125.00%) across all comparisons. Pharmacodynamic parameters, based on the percent of change from baseline in serum C-terminal telopeptide of Type 1 collagen levels, were similar across the three arms. The treatments were considered safe and generally well tolerated, with 92 treatment-emergent adverse events reported (most Grade 2 and 3) and similarly distributed. Immunogenicity was low and similarly distributed. These results provide strong evidence that supports the biosimilarity between MB09 and denosumab reference products.

Exploring various measures of the area under the curve for the assessment of dose-proportionality and estimation of bioavailability.

In pharmacokinetics, the area under the concentration versus time curve (AUC) extrapolated to infinity (AUC0-∞) is the preferred metric but it is not always possible to have a reliable estimate of the terminal phase half-life. Here we sought to explore the accuracy of three different area measures to accurately identify dose proportionality and bioavailability. One to three compartment model simulations with different doses for dose-proportionality or different rates and/or extents of bioavailability. Area measures evaluated were AUC0-∞, to the last quantifiable concentration (AUCtlast), and to a common time value (AUCt'). Under linear pharmacokinetics, AUCt' provided the most accurate measure of dose proportionality. Except for the one compartment model where AUC0-∞ provided the best predictor of the true measure, there was no clear advantage to the use of either of the three measures of AUC. With uncertainty about the terminal phase half-life, the use of AUCt' can be a very useful and even the preferred measure of exposure for use in assessing proportionality in exposure between doses. The choice of AUC measure in bioavailability is less clear and may depend on compartmental nature of the drug, and study parameters including assay sensitivity and sampling protocols.

Population Pharmacokinetics and CD20 Binding Dynamics for Mosunetuzumab in Relapsed/Refractory B-Cell Non-Hodgkin Lymphoma (R/R NHL)

Introduction: Mosunetuzumab (Mosun) is a CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells. Clinical data from GO29781 (NCT02500407), a Phase I/II, open-label, multicenter dose-escalation and expansion study of Mosun in pts with relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL), was used to develop a population pharmacokinetic (popPK) model describing Mosun concentration-time data. Prior to initiation of Mosun, many patients had circulating levels of other anti-CD20 drugs (e.g. rituximab (R) or obinutuzumab (G)) from prior treatment. In order to elucidate exposure-response (ER) relationships in the presence of these competitors, CD20 binding and R/G pharmacokinetics were incorporated into the popPK model to calculate the Mosun CD20 receptor occupancy percentage (RO%) over time. Methods: Mosun PK data were available in 439 pts with indolent or aggressive R/R NHL who received either Mosun fixed dosing (n= 32; 0.05-2.8mg every 3 weeks (q3w)) or Cycle 1 step-up dosing (n=407, 0.4/1.0/2.8 - 1/2/60/30mg). The popPK model was developed using NONMEM® software (v7.4.3), with a clinical cut-off date of December 4, 2020. Clinically relevant covariates were investigated for their potential to explain Mosun PK variability. The Mosun CD20 RO% time course for each pt was derived by integrating the Mosun, R, and G model predicted concentration-time courses and their respective CD20 affinities (Kds) into the popPK model. R and G concentration-time courses were predicted by the model using their baseline values and published half-lives, and binding kinetics were assumed to be at equilibrium. PopPK model simulations (n=1000) were done with the final model to establish Mosun concentration ranges for the approved 1/2/60/30 mg dose regimen, given that this regimen was designed to mitigate cytokine release syndrome (CRS) through its step-up Cycle 1 design. Additional popPK model simulations, incorporating Mosun dose delays, were conducted and compared to the 1/2/60/30 mg nominal dose regimen to inform treatment resumption protocols necessary to mitigate CRS. Results : A two-compartment PK model with time-dependent clearance (CL) best described Mosun PK. Mosun CL decreased from an initial value of 1.08 L/day transitioning to a steady state clearance of 0.584 L/day by Cycle 4 (Figure 1A). Mosun terminal phase half-life at steady state was 16.1 days. Concentrations of R/G were present in 50% of patients prior to Mosun therapy (Figure 1A), and the median predose R/G concentration for these patients was 10.0 µg/mL. Statistically relevant covariates on PK parameters included body weight, albumin, sex, tumor burden, and baseline concentrations of R/G; however, no covariate was deemed to have a clinically relevant impact on PK at the recommended dose of 1/2/60/30mg. Mosun CD20 RO% was more variable than Mosun PK (Figure 1B), attributed to the large variability in baseline R/G concentrations. The 60mg loading doses increased Mosun CD20 RO% to steady-state ranges by Cycle 1 (Figure 1B), thereby providing Mosun efficacious exposure in the presence of competing residual, transient R/G concentrations from prior treatment therapies (Figure 1A). From the popPK model simulations, patients with dose delays greater than or equal to 6 weeks had Mosun concentrations that fell below levels after the Day 1 (1mg) and Day 8 (2mg) doses; as such, these pts are instructed to repeat these doses prior to treatment continuation. For Mosun dose delays less than 6 weeks, popPK simulations supported pts either to repeat the last Mosun dose administered, or to continue along with the planned regimen [Lunsumio ® USPI]. Conclusions: Mosun PK was characterized using a two-compartment model with time dependent CL. R/G PK and CD20 binding kinetics were incorporated into the Mosun popPK model to calculate Mosun CD20 RO% over time. The use of two 60mg loading doses enables early achievement of Mosun steady-state target CD20 RO% range, especially benefitting those pts with high levels of precirculating R or G. Simulations with the popPK model supported labeling recommendations for restarting Mosun treatment after dose delays. Acknowledgments: This study was sponsored by F. Hoffmann-La Roche Ltd / Genentech, Inc

THE METABOLISM OF LUFOTRELVIR, A PRODRUG INVESTIGATED FOR THE TREATMENT OF SARS-COV-2, IN HUMANS FOLLOWING INTRAVENOUS ADMINISTRATION.

The metabolism of lufotrelvir, a novel phosphate prodrug of PF-00835231 for the treatment of COVID-19, was evaluated in healthy human volunteers and clinical trial participants with COVID-19 following intravenous infusion. The prodrug was completely converted to PF-00835231 which was subsequently cleared by hydrolysis, hydroxylation, ketoreduction, epimerization, renal clearance, and secretion into the feces. The main circulating metabolite was a hydrolysis product (M7) which was present at concentrations greater than PF-00835231, and this was consistent between healthy volunteers and participants with COVID-19. Upon administration of [14C]lufotrelvir, only 63% of the dose was obtained in excreta over 10 days and total drug-related material demonstrated a prolonged terminal phase half-life in plasma. A considerable portion of the labelled material was unextractable from fecal homogenate and plasma. The position of the carbon-14 atom in the labelled material was at a leucine carbonyl, and pronase digestion of the pellet derived from extraction of the fecal homogenate showed that [14C]leucine was released. Significance Statement Lufotrelvir is an experimental phosphate prodrug intravenous therapy investigated for the potential treatment of COVID-19 in a hospital setting. The overall metabolism of lufotrelvir was determined in human healthy volunteers and clinical trial participants with COVID-19. Conversion of the phosphate prodrug to the active drug PF-00835231 was complete and the subsequent metabolic clearance of the active drug was largely via amide bond hydrolysis. Substantial drug-related material was not recovered due to loss of the carbon-14 label to endogenous metabolism.

Tenecteplase: A Review of Its Pharmacology and Uses.

Tenecteplase: A Review of Its Pharmacology and Uses.

A Single- and Multiple-Dose Pharmacokinetic Study of Oral Perampanel in Healthy Chinese Subjects.

Perampanel is a once-daily oral anti-seizure medication indicated for focal-onset seizures and generalized tonic-clonic seizures. This study investigated the single- and multiple-dose pharmacokinetics of perampanel in healthy Chinese adults. Study 052 (NCT03424564) was a phase I, single-center, open-label, parallel-group study. In the single-dose part of the study, subjects received a single oral dose of perampanel 2, 4, or 8 mg. In the multiple-dose part, subjects received once-daily oral perampanel 2 mg on Days 1-7 and 4 mg on Days 8-21. Pharmacokinetic parameters were determined from perampanel plasma concentrations using non-compartmental analysis. Dose proportionality after single doses of perampanel was assessed. Safety and tolerability were evaluated. In the single-dose part (N=30), median time to reach maximum concentration (tmax) was 0.75-1.0h, mean terminal elimination phase half-life (t½) was 85.6-122h, mean maximum observed concentration (Cmax) was 77.9-276 ng/mL, and mean area under the concentration-time curve from time zero to time of the last quantifiable concentration (AUC(0-t)) was 4070-15100 ng·h/mL. Single-dose pharmacokinetics were linear for perampanel 2-8 mg. In the multiple-dose part (N=12), Day 21 steady-state (4 mg/day) parameters were median time at which the highest drug concentration occurs at steady state (tss,max), 1.25h; mean t½, 109h; mean maximum observed concentration at steady state (Css,max), 453ng/mL; and mean area under the concentration-time curve over the dosing interval on multiple dosing (AUC(0- τ)), 7540 ng·h/mL. For single- and multiple-dose perampanel, the most common treatment-emergent adverse events were dizziness and somnolence. Single- and multiple-dose pharmacokinetics of perampanel in healthy Chinese adults revealed rapid perampanel absorption, slow elimination, and a linear relationship with single perampanel doses of 2-8 mg. Findings were consistent with previous studies of perampanel pharmacokinetics in other ethnic/racial populations of healthy subjects. Single and multiple doses of perampanel were generally safe and well tolerated. NCT03424564; registered February 2018.

Pharmacokinetics, metabolite profiling, safety, and tolerability of inhalation aerosol of 101BHG-D01, a novel, long-acting and selective muscarinic receptor antagonist, in healthy Chinese subjects.

101BHG-D01 is a novel, long-acting, selective muscarinic receptor antagonist for the treatment of chronic obstructive pulmonary disease (COPD). A single-site, randomized, double-blind, placebo-controlled and dose-escalation study of 101BHG-D01 inhalation aerosol was conducted to evaluate its pharmacokinetics, metabolite profiling, safety and tolerability following the single inhaled doses ranged from 20 to 900μg in healthy Chinese subjects. After inhalation, 101BHG-D01 was absorbed rapidly into plasma with the time to maximum concentration about 5min, and eliminated slowly with the terminal phase half-life about 30h. The cumulative excretion rates of 101BHG-D01 in feces and urine were about 30% and 2%, respectively, which showed the study drug was mainly excreted in feces. The maximum drug concentration and area under the plasma concentration-time curve increased with dose escalation in the range of 20-600μg, but their values increased out of proportion to the whole studied doses. The main metabolic pathways were loss of phenyl group and hydroxylation. No metabolite that presented at greater than 10 percent of total drug-related exposure was observed. 101BHG-D01 was safe and well tolerated after administration. The study results indicate that 101BHG-D01 is a good candidate for the treatment of COPD and enable further clinical development in subsequent studies in patients. Clinical Trial Registration: http://www.chinadrugtrials.org.cn; Identifier: CTR20192058.

Pharmacokinetics and Safety of Vedolizumab Following Administration of a Single Intravenous Dose in Healthy Chinese Subjects.

Vedolizumab is a humanized monoclonal antibody, indicated for the treatment of moderately to severely active ulcerative colitis (UC) or Crohn's disease (CD), that specifically binds to the α4β7 integrin. The aim of this study was to assess the pharmacokinetics, safety, and tolerability of vedolizumab following a single intravenous (IV) infusion in healthy adult Chinese subjects. Sixteen participants received a single IV infusion of vedolizumab (300mg). Blood samples were collected to measure vedolizumab serum concentrations. The safety of all subjects was monitored. The pharmacokinetic analysis showed that vedolizumab reached the maximum observed serum concentration (Cmax) at approximately 1.32hours. The mean Cmax and area under the concentration-time curve from time 0 to time of the last quantifiable concentration (AUC0-t) and to infinity (AUC0-∞) were 137.25µg/mL, 2360days·µg/mL, and 2395days·µg/mL, respectively. The elimination of vedolizumab was relatively slow, with a mean terminal disposition phase half-life elimination (t1/2) of 20.23days. Six subjects were positive for anti-vedolizumab antibodies (AVAs) on day 106 and day 127. Finally, 4 out of 16 subjects (25.0%) had treatment-emergent adverse events (TEAEs), all of which were upper respiratory tract infections. Vedolizumab was well tolerated in healthy Chinese subjects when administered as a single-dose IV 300mg infusion. In this study, the rate of AVA positivity was 37.5%, which occurred near the end of the study; no significant differences in pharmacokinetic profiles were observed between the AVA-positive and AVA-negative groups. http://www.chinadrugtrials.org.cn : CTR20171528.

Abstract 5216: Optimizing antitumor efficacy of granzyme B human fusion constructs targeting the Fn14 antigen in solid tumors. Pre IND pharmacokinetics, schedule, dose optimization and MTD studies

Abstract We previously demonstrated that a human fusion protein construct targeting the Fn14 receptor and containing the cytotoxic granzyme B (GrB) payload (GrB-Fc-IT4) displays impressive in vitro and in vivo cytotoxic effects. Comprehensive mechanism of action studies show that GrB-Fc-IT4 effectively induces cell death in vitro against a broad selection of tumor types with high specificity. The intracellular pathway includes irreversible activation of the caspase cascade and independent mitochondrial depolarization leading to an intense apoptotic cellular damage. This activation occurs quickly and efficiently. Pharmacokinetic studies in mice showed that GrB-Fc-IT4 was cleared bi-exponentially from plasma with a rapid initial clearance (t ½alpha = 0.36 hours) followed by a prolonged terminal-phase plasma half-life (t 1/2beta = 35 hours) similar to that of IgGs. Based on our pharmacokinetic study, we employed a QODX5 therapy schedule and demonstrated impressive antitumor activity against several tumor models including PDX-lung, A459 (NSCLC) and MDA-MB231(TNBC) tumor models. In the present study we compared the in vivo antitumor efficacy of GrB-Fc-IT4 against A549 (NSCLC) tumor cell line, using two different dosing schedules (QODx5 vs QWx5). There was a clear dose and schedule dependence and that treating mice bearing A549 tumors with 32mg/kg/dose using a QOWx5 schedule induced a complete tumor growth inhibition (7/10 tumors regressed) with 3/10 tumors showing no growth up to 50 days after the last dose. Preliminary results suggest that GrB-Fc-IT4 may reduce the formation of spontaneous A549 metastasis into lungs. Further studies are planned to examine the potential of the fusion construct to prevent spontaneous metastatic spread in lung tumor models. Although the fusion construct cross-reacts with the murine Fn14 antigen, maximum tolerated dose studies have confirmed that GrB-Fc-IT4 is a safe product, showing no evidence of toxicity (weight loss) in mice treated with up to 500mg/kg. This suggests that the therapeutic index (TI) for this class of agents is >4. Our data suggest that GrB-Fc-IT4 is a novel class of antitumor agents with a unique mechanism of action. This agent seems to be an exceptionally safe and effective drug and appears to be an ideal candidate for advancing to clinical trials. Research conducted, in part, by Clayton Foundation for Research. Citation Format: Ana Alvarez De Cienfuegos, Lawrence H. Cheung, Khalid A. Mohamedali, Mihai Gagea, Michael G. Rosenblum. Optimizing antitumor efficacy of granzyme B human fusion constructs targeting the Fn14 antigen in solid tumors. Pre IND pharmacokinetics, schedule, dose optimization and MTD studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5216.

Pharmacokinetic Evaluation of a Cannabidiol Supplement in Horses

Cannabidiol (CBD) products have gained popularity among horse owners despite limited evidence regarding pharmacokinetics. The purpose of this study was to describe the pharmacokinetic profile of multiple doses of an orally administered cannabidiol product formulated specifically for horses. A randomized 2-way crossover design was used. Seven horses received 0.35 or 2.0 mg/kg CBD per os every 24 hours for 7 total doses, separated by a 2-week washout. Plasma CBD and delta-9-tetrahydrocannabinol (THC) were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) daily through day 10, then on day 14 after beginning CBD administration. On the final day of CBD administration, plasma CBD and THC were quantified at multiple times. After administration of 0.35 mg/kg of CBD, the Cmax of CBD was 6.6 ± 2.1 ng/mL while Tmax was 1.8 ± 1.2 hour, whereas the Cmax for THC was 0.7 ± 0.6 ng/mL with a Tmax of 2.5 ± 1 hour. After administration of 2.0 mg/kg of CBD, the Cmax of CBD was 51 ± 14 ng/mL with a mean Tmax of 2.4 ± 1.1 hour and terminal phase half-life of 10.4 ± 6 hour, whereas the Cmax of THC was 7.5 ± 2.2 ng/mL with a Tmax of 2.9 ± 1.1 hour. Oral administration of a cannabidiol product at 0.35 mg/kg or 2.0 mg/kg once daily for 7 days was well-tolerated. Based on plasma CBD levels obtained, dose escalation trials in the horse evaluating clinical efficacy at higher mg/kg dose rates are indicated.

A double-blind, placebo-controlled, single-ascending dose study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue, in healthy subjects.

To evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamics of HM15136, a novel long-acting glucagon analogue under development, in healthy males and females presenting with no childbearing potential. A randomized, double-blind, placebo-controlled, single-ascending dose study was conducted in 56 subjects who randomly received a single subcutaneous dose of HM15136 or its matching placebo at a ratio of 6:2 at 10, 20, 30, 50, 80, 100, and 120 μg/kg. All adverse events were mild and transient. Neither serious adverse events nor discontinuation as a result of adverse events occurred. The most frequent adverse drug reaction was nausea (5.3%, only in the 100- and 120-μg/kg groups). HM15136, particularly at doses of 50 μg/kg or higher, increased fasting blood glucose, with a maximum increase and area under the curve of 1.5 mmol/L at day 10 (P= .006) and 166.3day·mmol/L (P= .022) at the dose of 80 μg/kg, while suppressing the secretion of endogenous glucagon, which continued until day 17. HM15136 also significantly reduced gluconeogenic and ketogenic amino acids. Compensatory changes in endogenous insulin and incretin hormones by HM15136 were not apparent. HM15136 was slowly but steadily absorbed and reached a peak concentration at 46-68 hours after a single subcutaneous injection. HM15136 was eliminated with a terminal phase half-life of 77.1-101.1hours. A single subcutaneous dose of HM15136 at 10-120 μg/kg was safe and well tolerated. The long half-life of HM15136, coupled with an increase in blood glucose for ~2 weeks, may warrant a weekly dosing regimen.

Plasma and joint tissue pharmacokinetics of two doses of oral cannabidiol oil in guinea pigs (Cavia porcellus).

Cannabidiol (CBD) has gained widespread popularity as a treatment for osteoarthritis (OA) in pets; however, there is minimal scientific evidence regarding safe and effective dosing. This study determined plasma and tissue pharmacokinetics after oral CBD oil suspension administration in Hartley guinea pigs (Cavia porcellus), which spontaneously develop OA at 3months of age. Ten, 5-month-old, male guinea pigs were randomly assigned to receive 25 (n=5) or 50mg/kg (n=5) CBD oil once orally. Blood samples were collected at 0, 0.25, 0.5, 1, 2, 4, 8, 12, and 24h timepoints. Open-field enclosure monitoring revealed no adverse effects. After euthanasia, stifle cartilage and infrapatellar fat pads were collected to quantitate CBD. CBD concentrations were determined using a validated liquid chromatography-mass spectrometry method, and pharmacokinetic parameters were calculated using noncompartmental analysis. The area under the plasma concentration-versus-time curve was 379.5 and 873.7h*ng/mL, maximum plasma concentration was 42 and 96.8ng/mL, time to maximum plasma concentration was 1.6 and 4.8h, and terminal phase half-life was 8.1 and 10.8h for the 25 and 50mg/kg doses, respectively. CBD was detected in joint tissues of all animals. Further studies, including work in female guinea pigs, are needed to determine the efficacy of CBD for OA.

Evaluation of analgesic interaction between morphine, maropitant and dexmedetomidine in dogs undergoing ovariohysterectomy

ABSTRACT Aims To compare the analgesic effect of morphine combined with maropitant and/or dexmedetomidine to morphine alone but at a higher dose, and to evaluate the pharmacokinetics of the drug combinations, in dogs undergoing ovariohysterectomy (OHE). Methods Forty client-owned dogs were randomised into four treatment groups (n = 10 per group) each to receive a different analgesic protocol. After premedication with I/M acepromazine, anaesthesia was induced with propofol to effect and maintained with isoflurane in 100% oxygen delivered via a circle system. The heart rate, respiratory rate, blood pressure, haemoglobin oxygen saturation, end-tidal partial pressure of carbon dioxide, electrocardiogram and rectal temperature were monitored during anaesthesia. The test drugs (Mor: 0.6 mg/kg morphine; Maro + Mor: 0.3 mg/kg morphine and 1 mg/kg maropitant; Dex + Mor: 0.3 mg/kg morphine and 10 μg/kg dexmedetomidine; Dex + Maro + Mor: 0.2 mg/kg morphine, 7 μg/kg dexmedetomidine and 0.7 mg/kg maropitant) were administered I/M after induction of anaesthesia and 30 minutes before the expected start time of ovariohysterectomy, which was carried out by veterinary students under veterinary supervision. The short form of the Glasgow composite measure pain scale (CMPS-SF) and visual analogue scale (VAS) were used for pain assessment at 15 and 30 minutes and 1, 2, 3, 6, 9 and 24 hours after extubation. Dogs with CMPS-SF pain score ≥ 6 received rescue analgesia with S/C buprenorphine (0.02 mg/kg). Blood samples were collected before, 15, 30, 60 and 120 minutes after injection of the test drugs and concentration of the test drugs in plasma was determined by liquid chromatography-mass spectrometry. Results Dogs that received Dex + Mor had significantly lower CMPS-SF (estimate of difference = –1.53 (SE 0.58); p = 0.010) and VAS (estimate of difference = –0.67 (SE 0.25); p = 0.007) scores compared to the dogs that received morphine alone. There was no evidence of a difference in the number of dogs requiring rescue between groups. All dogs that received dexmedetomidine showed cardiac arrhythmia and second-degree heart block. Mean (SD) maximum concentrations (Cmax, ) of morphine in plasma were 6.8 (4.56), 9.56 (8.29), 9.30 (3.35) and 18.99 (9.41) ng/mL for the groups Dex + Mor, Dex + Maro + Mor, Maro + Mor and Mor respectively. The Cmax of morphine was significantly lower in the Dex + Mor (p = 0.004), Dex + Maro + Mor (p = 0.034) and Maro + Mor (p = 0.018) groups compared to the Mor group. Conclusions For dogs undergoing ovariohysterectomy, lower doses of morphine (0.2 and 0.3 mg/kg) combined with dexmedetomidine or maropitant may provide analgesia equivalent to or better than morphine when given alone at a higher dose (0.6 mg/kg). Abbreviations: AUC: Area under curve; Cmax: Maximum concentration in plasma; CMPS-SF: Glasgow composite measure pain scale – short form; NK1: Neurokinin-1; OHE: Ovariohysterectomy; Tmax: Time to Cmax; T1/2: Half-life of terminal elimination phase; VAS: Visual analogue scale

Tail-phase safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir in HIV-uninfected adults: a secondary analysis of the HPTN 077 trial

Long-acting injectable cabotegravir is a novel integrase inhibitor currently in advanced clinical development for HIV prevention and treatment. We aimed to assess the terminal phase pharmacokinetics and safety of long-acting injectable cabotegravir in participants included in the HPTN 077 trial. HPTN 077 was a multicentre, double-blind, randomised, placebo-controlled phase 2a trial done at eight sites in Brazil, Malawi, South Africa, and the USA. Participants (aged 18-65 years), who were HIV-uninfected and at low-risk for HIV, were randomly assigned (3:1) to long-acting injectable cabotegravir (800 mg given three times at 12 week intervals or 600 mg given five times, administered at one 4 week interval, and every 8 weeks thereafter) or placebo. Participants were followed up to 76 weeks after final injection. In a prespecified analysis of secondary and exploratory outcomes, we assessed the safety, measured by the proportion of participants with grade 2 or worse adverse events, and pharmacokinetics, measured by apparent terminal phase half-life (t1/2app) and estimated time to lower limit of quantification (LLOQ) of long-acting injectable cabotegravir during the injection phase (defined as the time between first injection and 12 weeks or 8 weeks after the last injection in cohort 1 or cohort 2 respectively) and tail phase (defined as the time between final injection and 52-76 weeks post-final injection). Safety was analysed in all participants who received at least one injection. Pharmacokinetic analyses included all participants who had received at least one injection and had at least three cabotegravir measurements higher than the LLOQ after the final injection. Pharmacokinetic outcomes were estimated using non-compartmental methods. The trial is completed, and was registered with ClinicalTrials.gov, NCT02178800. Between Feb 9, 2015, and May 27, 2016, 177 participants (134 participants in the cabotegravir group [74 participants in cohort 1; 60 participants in cohort 2] and 43 participants in the placebo group [25 participants in cohort 1; 18 participants in cohort 2) were enrolled and received at least one injection and thus were included in the safety analysis. The incidence of grade 2 or worse adverse events was significantly lower during the tail phase than the injection phase (p<0·0001). At 52-60 weeks after final injection, nine (23%) of 40 male participants had detectable cabotegravir concentrations and at week 76, four (13%) of 30 male participants had detectable cabotegravir concentrations compared with 52 (63%) of 82 female participants and 27 (42%) of 64 female participants at the same timepoints. The median time from the last injection to the time when cabotegravir concentration decreased below the LLOQ was 43·7 weeks (IQR 31·1-66·6; range 20·4-152·5) for male participants and 67·3 weeks (29·1-89·6; 17·7-225·5) for female participants (p=0·0003). t1/2app was longer for female participants than male participants (geometric mean fold-change 1·33, 95% CI 1·06-1·68; p=0·014), and longer for participants with a high body-mass index (BMI) than those with a low BMI (1·31, 1·06-1·63; p=0·015). The clinical significance of the long pharmacokinetic tail of cabotegravir observed in female participants compared with male participants, and those with higher BMI compared with a lower BMI, need to be addressed in future trials. National Institute of Allergy and Infectious Diseases.

Overview of the Clinical Pharmacology of Ertugliflozin, a Novel Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitor.

Ertugliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), is approved in the US, EU, and other regions for the treatment of adults with type 2 diabetes mellitus (T2DM). This review summarizes the ertugliflozin pharmacokinetic (PK) and pharmacodynamic data obtained during phase I clinical development, which supported the registration and labeling of this drug. The PK of ertugliflozin was similar in healthy subjects and patients with T2DM. Oral absorption was rapid, with time to peak plasma concentrations (Tmax) occurring at 1 h (fasted) and 2 h (fed) postdose. The terminal phase half-life ranged from 11 to 18 h and steady-state concentrations were achieved by 6 days after initiating once-daily dosing. Ertugliflozin exposure increased in a dose-proportional manner over the tested dose range of 0.5–300 mg. Ertugliflozin is categorized as a Biopharmaceutical Classification System Class I drug with an absolute bioavailability of ~ 100% under fasted conditions. Administration of the ertugliflozin 15 mg commercial tablet with food resulted in no meaningful effect on ertugliflozin area under the plasma concentration–time curve (AUC), but decreased peak concentrations (Cmax) by 29%. The effect on Cmax is not clinically relevant and ertugliflozin can be administered without regard to food. Mild, moderate, and severe renal impairment were associated with a ≤ 70% increase in ertugliflozin exposure relative to subjects with normal renal function, and no dose adjustment in renal impairment patients is needed based on PK results. Consistent with the mechanism of action of SGLT2 inhibitors, 24-h urinary glucose excretion decreased with worsening renal function. In subjects with moderate hepatic impairment, a decrease in AUC (13%) relative to subjects with normal hepatic function was observed and not considered clinically relevant. Concomitant administration of metformin, sitagliptin, glimepiride, or simvastatin with ertugliflozin did not have clinically meaningful effects on the PK of ertugliflozin or the coadministered medications. Coadministration of rifampin decreased ertugliflozin AUC and Cmax by 39% and 15%, respectively, and is not expected to affect efficacy in a clinically meaningful manner. This comprehensive evaluation supports administration to patients with T2DM without regard to prandial status and with no dose adjustments for coadministration with commonly prescribed drugs, or in patients with renal impairment or mild-to-moderate hepatic impairment based on ertugliflozin PK.

Abstract P1-18-16: A phase 1 study of ARX788, a HER2-targeting antibody-drug conjugate, in patients with metastatic HER2-positive breast cancer

Abstract Background: ARX788 is a novel site-specific antibody drug conjugate (ADC) that consists of a human epidermal growth factor receptor 2 (HER2) targeting monoclonal antibody (mAb) linked to the cytotoxic payload AS269, a highly potent tubulin inhibitor. Through a proprietary technology, a non-natural amino acid is precisely incorporated into the pre-determined site on the heavy chain of the mAb, and AS269 is specifically conjugated to the non-natural amino acid. In the first-in-human study in Australia/New Zealand (NCT02512237), delayed drug-induced pneumonitis, which occurred after 4-5 cycles of administration, were observed in participants at dose levels of 1.3 mg/kg Q3W or higher. Here, we present results of a phase I study (CTR20171162) to evaluate safety, pharmacokinetics, and preliminary antitumor effect of ARX788 in Chinese patients with metastatic HER2-positive breast cancer, with special focus on the delayed pneumonitis. Methods: Patients with metastatic HER2-positive breast cancer received intravenous ARX788 at doses of 0.33, 0.66, 0.88, 1.1, 1.3, 1.5 mg/kg Q3W or 0.88, 1.1, 1.3 mg/kg Q4W. The DLT assessment period was set to be 21 days in 0.33, 0.66 mg/kg Q3W cohorts, and additional 63 days (total 84 days) in other dose cohorts for the pulmonary toxicity. Dose cohorts were expanded at 1.1 and 1.3 mg/kg Q3W. Safety and tolerability were assessed by monitoring adverse events (AEs) and antitumor effects were evaluated according to the RECIST v1.1 criteria. Pulmonary toxicity of special interest was assessed every 2 cycles of therapy by CT imaging. Serum concentrations of ARX788 ADC, total antibody, and metabolite pAF-AS269 were measured and PK parameters were calculated. Results: As of 3 July 2019, 45 female Chinese participants with age range from 30 to 67 received ARX788, with 31 of whom had been treated for at least 84 days. No dose-limiting toxicities and treatment-related serious adverse events were observed. Serious blood and liver toxicity that are commonly associated with ADCs were rarely observed (only one participant experienced Grade 4 neutrophil count decreased on cycle 18 and none for ≥Grade 3 liver toxicity). Adverse events that required special attentions were ocular and pulmonary toxicity. Ocular events were mostly mild to moderate in severity and were reversible. Three participants experienced Grade 2 drug-related pneumonitis observed on days 130, 172 and 224, all of whom resolved after steroid treatment and re-started ARX788 treatment with dose reduction. ARX788 ADC serum exposure increased with dose increment and the mean terminal phase half-life ranged between 2.3 and 4.9 days. Among 42 evaluated participants, the overall response rate was 31% (13/42) and 42% (5/12) in 1.3 mg/kg Q3W cohort. One participant in 0.88 mg/kg Q3W cohort has undergone the treatment for more than 17 months. Conclusions: ARX788 was well tolerated in heavily-pretreated patients with HER2-positive metastatic breast cancer without evidence of Grade 3 or greater pneumonitis. Encouraging overall response rate was observed in 1.3 mg/kg Q3W cohort. Considering the predicted benefit/risk profile, 1.3 mg/kg Q3W is the recommended dose for further development of ARX788 in HER2-positive breast cancer. Citation Format: Xichun Hu, Jian Zhang, Dongmei Ji, Gang Xia, Yanping Ji, Gaozhun Xiong, Xuejun Liang. A phase 1 study of ARX788, a HER2-targeting antibody-drug conjugate, in patients with metastatic HER2-positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-18-16.

Lower respiratory tract delivery, airway clearance, and preclinical efficacy of inhaled GM-CSF in a postinfluenza pneumococcal pneumonia model

Inhaled granulocyte/macrophage colony-stimulating factor (GM-CSF) shows promise as a therapeutic to treat viral and bacterial pneumonia, but no mouse model of inhaled GM-CSF has been described. We sought to 1) develop a mouse model of aerosolized recombinant mouse GM-CSF administration and 2) investigate the protection conferred by inhaled GM-CSF during influenza A virus (IAV) infection against secondary bacterial infection with pneumococcus. To assess lower respiratory tract delivery of aerosolized therapeutics, mice were exposed to aerosolized fluorescein (FITC)-labeled dextran noninvasively via an aerosolization tower or invasively using a rodent ventilator. The efficiency of delivery to the lower respiratory tracts of mice was 0.01% noninvasively compared with 0.3% invasively. The airway pharmacokinetics of inhaled GM-CSF fit a two-compartment model with a terminal phase half-life of 1.3 h. To test if lower respiratory tract levels were sufficient for biological effect, mice were infected intranasally with IAV, treated with aerosolized recombinant mouse GM-CSF, and then secondarily infected with Streptococcus pneumoniae. Inhaled GM-CSF conferred a significant survival benefit to mice against secondary challenge with S. pneumoniae (P < 0.05). Inhaled GM-CSF did not reduce airway or lung parenchymal bacterial growth but significantly reduced the incidence of S. pneumoniae bacteremia (P < 0.01). However, GM-CSF overexpression during influenza virus infection did not affect lung epithelial permeability to FITC-dextran ingress into the bloodstream. Therefore, the mechanism of protection conferred by inhaled GM-CSF appears to be locally mediated improved lung antibacterial resistance to systemic bacteremia during IAV infection.

Criteria for reporting noncompartmental estimates of half-life and area under the curve extrapolated to infinity.

Various criteria have been proposed for determining the reliability of noncompartmental pharmacokinetic estimates of the terminal disposition phase half-life (t1/2 ) and the extrapolated area under the curve (AUCextrap ). This simulation study assessed the performance of two frequently used reportability rules: the terminal disposition phase regression adjusted-r2 classification rule and the regression data point time span classification rule. Using simulated data, these rules were assessed in relation to the magnitude of the variability in the terminal disposition phase slope, the length of the terminal disposition phase captured in the concentration-time profile (data span), the number of data points present in the terminal disposition phase, and the type and level of variability in concentration measurement. The accuracy of estimating t1/2 was satisfactory for data spans of 1.5 and longer, given low measurement variability; and for spans of 2.5 and longer, given high measurement variability. Satisfactory accuracy in estimating AUCextrap was only achieved with low measurement variability and spans of 2.5 and longer. Neither of the classification rules improved the identification of accurate t1/2 and AUCextrap estimates. Based on the findings of this study, a strategy is proposed for determining the reportability of estimates of t1/2 and area under the curve extrapolated to infinity.

Safety, PK and preliminary efficacy of talazoparib in Japanese patients with advanced solid tumors; Phase 1 Study

Abstract Background Talazoparib is a potent, orally bioavailable, small molecule poly (adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor. The recommended dose (RD) of single-agent talazoparib in non-Japanese patients (pts) was determined as 1 mg/day [QD]. This ongoing Phase 1 study evaluated the safety, preliminary efficacy, and PK profile of single-agent talazoparib in Japanese pts with advanced solid tumors. Methods Primary endpoint was first-cycle dose limiting toxicity (DLT). The single dose and multiple-dose PK and anti-tumor activity were evaluated as secondary endpoints. Two dose levels (0.75 mg and 1 mg QD) of talazoparib were studied using modified 3 + 3 dose escalation scheme. Talazoparib was administered continuously with the cycle length of 28 days. Results A total of 9 pts (3 pts in 0.75 mg and 6 pts in 1 mg QD) with a variety of tumor types were enrolled. No DLT was reported in either dose levels. The most common treatment-related (TR) adverse events (AEs) were neutrophil count decreased, platelet count decreased and stomatitis (22.2%, 2 pts each). No grade 3 or more TRAEs were reported. Based on the preliminary PK analysis, the median time to reach maximum plasma concentration (Tmax) was ranging from 1.0 to 2.0 hours. Talazoparib was eliminated with terminal phase half-life ranging from 49 to 133 hours after single dose. The distributions of maximum plasma concentration (Cmax) and area under concentration-time curve (AUC) after single and multiple dose were within the range of those in non-Japanese pts. RD in Japanese pts was determined to be 1 mg QD. Conclusions No DLT was reported in Japanese pts who received up to 1 mg QD. Hematological toxicity was common AEs in Japanese pts as well as non-Japanese pts. RD in Japanese pts was determined as 1 mg QD. The PK profile in Japanese pts was comparable with that in non-Japanese pts. Now the study is expanding to evaluate the efficacy in Japanese pts with germline BRCA mutated advanced breast cancer.

Tail-Phase Safety, Tolerability, and Pharmacokinetics of Long-Acting Injectable Cabotegravir in HIV-Uninfected Adults: HPTN 077

Background: Long-acting injectable cabotegravir (CAB LA) is a novel integrase inhibitor in advanced clinical development for HIV treatment and HIV prevention. We investigated the terminal pharmacokinetics and safety of CAB LA after final injection as part of a Phase 2 study. Methods: We performed a randomized, double-blind placebo-controlled trial at 8 sites in the United States (US), sub-Saharan Africa, and Brazil. Participants, age 18-65, HIV-uninfected and at low-risk for HIV, were randomized 3:1 to CAB LA or placebo. Participants received CAB LA at one of two doses/intervals, which were aggregated for this analysis. The current analysis includes participants who received at least one injection and examines the tail phase (time from final injection to 52-76 weeks post-final injection). The outcomes were safety and pharmacokinetics. Safety was reported as incidence rates of grade 2 or higher adverse events. The apparent terminal phase half-life (t1/2app) and time to decay of CAB drug concentration to below the lower limit of quantification (LLOQ) were estimated using non-compartmental methods. Findings: Overall, 177 participants received at least one injection. Median age was 31 years, 66.1% were female, 69.5% were non-white, 52.5% were from the US. Rates of grade 2 or higher adverse events on CAB were higher in the injection phase compared to the tail phase. At one time point from 52-60 weeks and at 76 weeks after final injection, 22% and 13% of males, respectively, had detectable CAB concentrations; 63% and 48% of females had detectable CAB concentrations at those time points. The estimated median time from last injection to CAB concentration below the LLOQ was 43.7 (range 20-4-152.5) weeks for males and 67.3 (range 17.7-225.5) weeks for females. Terminal phase half-life was 33% longer for female sex at birth participants compared to male participants, and 31% longer for participants with body mass index (BMI) above vs. below the study median of 26. Interpretation: No new adverse events were observed with long-term follow-up. The long pharmacokinetic tail will need to be addressed in pivotal trials of treatment and prevention. Trial Registration: The trial was registered with ClinicalTrials.gov, number NCT02178800. This trial is completed. Funding Statement: National Institute of Allergy and Infectious Diseases (UM1AI068619, UM1AI068613, and, UM1AI068617) Declaration of Interests: RJL has received study medication, consulting fees and travel support from Gilead Sciences, and consulting fees and travel support from Merck, Inc. JJE is a consultant to Merck, Gilead Sciences, Janssen, and ViiV Healthcare; and he is an investigator on research contracts from ViiV Healthcare, Janssen, and Gilead Sciences. HD has received honoraria from Pfizer-South Africa, Novartis-South Africa, MSD-South Africa and Adcock Ingram for speaking engagements and has received travel support from Mylan-South Africa, Novartis-South Africa and Aspen-South Africa. AYL received research grants from NIH and has led studies in which study drug was donated by Gilead Sciences. MAM received grant support through the NIH and received grant support through ViiV/GSK on work external to this study. ARR and DM are paid employees of ViiV Healthcare. CWH has research contracts with NIH, ViiV/GlaxoSmithKline, Gilead Sciences, and Merck through Johns Hopkins. Ethics Approval Statement: Local institutional review boards or ethics committees at each participating site granted ethics and regulatory approvals of the protocol and all participants provided written informed consent.