Guide Dose Selection Research Articles

Preclinical Evaluation of MK-8189: A Novel Phosphodiesterase 10A Inhibitor for the Treatment of Schizophrenia.

MK-8189 is a novel phosphodiesterase 10A (PDE10A) inhibitor being evaluated in clinical studies for the treatment of schizophrenia. PDE10A is a cyclic nucleotide phosphodiesterase enzyme highly expressed in medium spiny neurons of the striatum. MK-8189 exhibits sub-nanomolar potency on the PDE10A enzyme and has excellent pharmaceutical properties. Oral administration of MK-8189 significantly increased cGMP and pGluR1 in rat striatal tissues. Activation of the dopamine D1 direct and D2 indirect pathways was demonstrated by detecting significant elevation of mRNA encoding substance P (Sub P) and enkephalin (ENK) after MK-8189 administration. The PDE10A tracer [3H]MK-8193 was used determine the PDE10A enzyme occupancy (EO) required for efficacy in behavioral models. In the rat conditioned avoidance responding assay, MK-8189 significantly decreased avoidance behavior at PDE10A EO greater than ~48%. MK-8189 significantly reversed an MK-801-induced deficit in pre-pulse inhibition at PDE10A EO of ~47% and higher. Target engagement of MK-8189 in rhesus monkeys was examined with [11C]MK-8193 in PET studies and plasma concentrations of 127nM MK-8189 yielded ~50% EO in the striatum. The impact of MK-8189 on cognitive symptoms was evaluated using the objective retrieval task in rhesus monkeys. MK-8189 significantly attenuated a ketamine-induced deficit in object retrieval performance at exposure that yielded ~29% PDE10A EO. These findings demonstrate the robust impact of MK-8189 on striatal signaling and efficacy in preclinical models of symptoms associated with schizophrenia. Data from these studies were used to establish the relationship between preclinical efficacy, plasma exposures, and PDE10A EO to guide dose selection of MK-8189 in clinical studies. Significance Statement We describe the primary pharmacology of MK-8189 a PDE10A inhibitor under evaluation for the treatment of schizophrenia. We report efficacy in preclinical models that have been used to characterize other PDE10A inhibitors and atypical antipsychotics. The PDE10A occupancy achieved by MK-8189 in behavioral studies was used to support dose selection in clinical trials. This work provides evidence to support exploration of higher levels of PDE10A occupancy in clinical trials to determine if this translates to improved efficacy in patients.

Use of a PK/PD Model to Select Cetagliptin Dosages for Patients with Type 2 Diabetes in Phase 3 Trials.

Cetagliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor developed for the treatment of patients with type 2 diabetes (T2D). Several phase 1 studies have been conducted in China. Modelling and simulation were used to obtain cetagliptin dose for phase 3 trials in T2D patients. A pharmacokinetic (PK)/pharmacodynamic (PD) model and model-based analysis of the relationship between hemoglobin A1c (HbA1c) and dosage was explored to guide dose selection of cetagliptin for phase 3 trials. The PK/PD data were derived from four phase 1 clinical studies, and sitagliptin 100 mg was employed as a positive control in studies 1, 3, and 4. The PK profiles of cetagliptin were well described by a two-compartment model with first-order absorption, saturated efflux, and first-order elimination. The final PD model was a sigmoid maximum inhibitory efficacy (Emax) model with the Hill coefficient. The final model accurately captured cetagliptin PK/PD, demonstrated by goodness-of-fit plots. Based on weighted average inhibition (WAI), the relationship between HbA1c and dose was well displayed. Cetagliptin 50 mg once daily or above as monotherapy or as add-on therapy appeared more effective in HbA1c reduction than sitagliptin 100 mg. Cetagliptin 50 mg or 100 mg once daily was selected as the dose for phase 3 trials of cetagliptin in T2D patients. The PK/PD model supports dose selection of cetagliptin for phase 3 trials. A model‑informed approach can be used to replace a dose-finding trial and accelerate cetagliptin's development.

56 Clinical Pharmacokinetic/Pharmacodynamic (PK/PD) Relationship Confirms Best-in-class Potential of Casdatifan (AB521), a Small Molecule Inhibitor of HIF-2α Being Developed in Renal Cancer

Abstract Background Casdatifan, an orally bioavailable small molecule inhibitor of HIF-2α, potently inhibits transcription of HIF-2α-dependent genes in cell lines and preclinical species. The objective of this analysis was to develop an understanding of the relationship between clinical dose, casdatifan PK, erythropoietin (EPO), a PD biomarker for peripheral (non-tumor) HIF-2α inhibition, and hemoglobin and to use this information to guide dose selection in future clinical trials. Methods Casdatifan plasma concentrations, serum EPO concentration, and hemoglobin data were obtained from 79 healthy participants in two Phase 1 studies, ARC-14 (NCT05117554) and ARC-28 (NCT05999513), and from 71 patients with clear cell renal cell carcinoma (ccRCC) and other solid tumors in an ongoing Phase 1 study, ARC-20 (NCT05536141). The available PK and PD data were collected following single oral doses of casdatifan ranging from 3 mg to 100 mg in healthy participants, and multiple oral doses of casdatifan ranging from 15 mg to 150 mg once daily (QD) in healthy participants and cancer patients. Serial PK, EPO, and Hb data were gathered in all study participants pre-dose till end of treatment. The population PKPD model was developed using mixed effects methodology with NONMEM software to relate dose, PK, and PD (EPO and Hb) data. Results Casdatifan showed dose-proportional increases in plasma exposure over the 3-150 mg dose range after single and multiple doses. Casdatifan PK was also invariant over time in patients with an approximately 2.0-fold accumulation at steady-state compared to first dose. The mean terminal half-life of casdatifan was approximately 24 h. The PK was similar in healthy participants and cancer patients. Dose-dependent reduction in EPO was observed after single and multiple doses in healthy participants and patients. A two-compartment model with first-order absorption adequately described the casdatifan plasma PK across the dose range tested. The effect of casdatifan plasma concentrations on EPO production rate was modeled using an inhibitory function. Analysis of the casdatifan dose-PD (EPO suppression) relationship indicated that casdatifan 20 mg once daily provided a similar level of EPO suppression in patients as belzutifan 120 mg daily (benchmark peripheral PD). Furthermore, due to the dose-proportional PK of casdatifan, the selected dose (100 mg daily) for further development results in plasma levels approximately 5 times higher than those associated with the benchmark peripheral PD. Conclusions Casdatifan exhibits dose-linear and time-invariant PK in the dose range 15-150 mg. Dose-dependent reduction in EPO levels, consistent with the mechanism of action of HIF-2α inhibition, was seen after casdatifan administration. A PKPD analysis of available data indicated that 20 mg daily dose of casdatifan would result in similar EPO effect as the registered dose of belzutifan. Available PKPD data and analyses indicated best-in-class properties of casdatifan.

Minimum effective dose of clemastine in a mouse model of preterm white matter injury

BackgroundPreterm white matter injury (PWMI) is the most common cause of brain injury in premature neonates. PWMI involves a differentiation arrest of oligodendrocytes, the myelinating cells of the central nervous system. Clemastine was previously shown to induce oligodendrocyte differentiation and myelination in mouse models of PWMI at a dose of 10 mg/kg/day. The minimum effective dose (MED) of clemastine is unknown. Identification of the MED is essential for maximizing safety and efficacy in neonatal clinical trials. We hypothesized that the MED in neonatal mice is lower than 10 mg/kg/day.MethodsMouse pups were exposed to normoxia or hypoxia (10% FiO2) from postnatal day 3 (P3) through P10. Vehicle or clemastine at one of four doses (0.5, 2, 7.5 or 10 mg/kg/day) was given to hypoxia-exposed pups. Myelination was assessed at age P14 and 10 weeks to determine the MED. Clemastine pharmacokinetics were evaluated at steady-state on day 8 of treatment.ResultsClemastine rescued hypoxia-induced hypomyelination with a MED of 7.5 mg/kg/day. Pharmacokinetic analysis of the MED revealed Cmax 44.0 ng/mL, t1/2 4.6 h, and AUC24 280.1 ng*hr/mL.ConclusionsBased on these results, myelination-promoting exposures should be achievable with oral doses of clemastine in neonates with PWMI.ImpactPreterm white matter injury (PWMI) is the most common cause of brain injury and cerebral palsy in premature neonates.Clemastine, an FDA-approved antihistamine, was recently identified to strongly promote myelination in a mouse model of PWMI and is a possible treatment.The minimum effective dose in neonatal rodents is unknown and is critical for guiding dose selection and balancing efficacy with toxicity in future clinical trials.We identified the minimum effective dose of clemastine and the associated pharmacokinetics in a murine chronic hypoxia model of PWMI, paving the way for a future clinical trial in human neonates.

Simulation-based evaluation of personalized dosing approaches for anti-FGFR/KLB bispecific antibody fazpilodemab.

Personalized dosing approaches play important roles in clinical practices to improve benefit: risk profiles. Whereas this is also important for drug development, especially in the context of drugs with narrow therapeutic windows, such approaches have not been fully evaluated during clinical development. Fazpilodemab (BFKB8488A) is an agonistic bispecific antibody which was being developed for the treatment of nonalcoholic steatohepatitis. The objective of this study was to characterize the exposure-response relationships of fazpilodemab with the purpose of guiding dose selection for a phase II study, as well as to evaluate various personalized dosing strategies to optimize the treatment benefit. Fazpilodemab exhibited clear exposure-response relationships for a pharmacodynamic (PD) biomarker and gastrointestinal adverse events (GIAEs), such as nausea and vomiting. Static exposure-response analysis, as well as longitudinal adverse event (AE) analysis using discrete-time Markov model, were performed to characterize the observations. Clinical trial simulations were performed based on the developed exposure-response models to evaluate probability of achieving target PD response and the frequency of GIAEs to inform phase II dose selection. Dynamic simulation of personalized dosing strategies demonstrated that the AE-based personalized dosing is the most effective approach for optimizing the benefit-risk profiles. The approach presented here can be a useful framework for quantifying the benefit of personalized dosing for drugs with narrow therapeutic windows.

A Population Model of Time-Dependent Changes in Serum Creatinine in (Near)term Neonates with Hypoxic-Ischemic Encephalopathy During and After Therapeutic Hypothermia

The objective was to apply a population model to describe the time course and variability of serum creatinine (sCr) in (near)term neonates with moderate to severe encephalopathy during and after therapeutic hypothermia (TH). The data consisted of sCr observations up to 10 days of postnatal age in neonates who underwent TH during the first 3 days after birth. Available covariates were birth weight (BWT), gestational age (GA), survival, and acute kidney injury (AKI). A previously published population model of sCr kinetics in neonates served as the base model. This model predicted not only sCr but also the glomerular filtration rate normalized by its value at birth (GFR/GFR0). The model was used to compare the TH neonates with a reference full term non-asphyxiated population of neonates. The estimates of the model parameters had good precision and showed high between subject variability. AKI influenced most of the estimated parameters denoting a strong impact on sCr kinetics and GFR. BWT and GA were not significant covariates. TH transiently increased sCr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm{sCr}$$\\end{document} in TH neonates over the first days compared to the reference group. Asphyxia impacted not only GFR, but also the sCr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm{sCr}$$\\end{document} synthesis rate. We also observed that AKI neonates exhibit a delayed onset of postnatal GFR increase and have a higher sCr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm{sCr}$$\\end{document} synthesis rate compared to no-AKI patients. Our findings show that the use of sCr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm{sCr}$$\\end{document} as marker of renal function in asphyxiated neonates treated with TH to guide dose selection for renally cleared drugs is challenging, while we captured the postnatal sCr patterns in this specific population.Graphical

Dose rationale for gabapentin and tramadol in pediatric patients with chronic pain.

Despite off-label use, the efficacy and safety of gabapentin and tramadol in pediatric patients (3 months to <18 years old) diagnosed with chronic pain has not been characterized. However, generating evidence based on randomized clinical trials in this population has been extremely challenging. The current investigation illustrates the use of clinical trial simulations (CTSs) as a tool for optimizing doses and protocol design for a prospective investigation in pediatric patients with chronic pain. Pharmacokinetic (PK) modeling and CTSs were used to describe the PKs of gabapentin and tramadol in the target population. In the absence of biomarkers of analgesia, systemic exposure (AUC, Css) was used to guide dose selection under the assumption of a comparable exposure-response (PKPD) relationship for either compound between adults and children. Two weight bands were identified for gabapentin, with doses titrated from 5 to 63 mg/kg. This yields gabapentin exposures (AUC0-8 ) of approximately 35 mg/L*h (1200 mg/day adult dose equivalent). For tramadol, median steady state concentrations between 200 and 300 ng/mL were achieved after doses of 2-5 mg/kg, but concentrations showed high interindividual variability. Simulation scenarios showed that titration steps are required to explore therapeutically relevant dose ranges taking into account the safety profile of both drugs. Gabapentin can be used t.i.d. at doses between 7-63 and 5-45 mg/kg for patients receiving gabapentin weighing <15 and ≥15 kg, respectively, whereas a t.i.d. regimen with doses between 1 and 5 mg/kg can be used for tramadol in patients who are not fast metabolisers.

Model based assessment of food and acid reducing agent effects on oral absorption of mezigdomide (CC-92480), a novel cereblon E3 ligase modulator.

Mezigdomide is a novel cereblon E3 ligase modulator (CELMoD) agent with enhanced autonomous cell-killing activity in multiple myeloma (MM) cells, and promising immunomodulatory and antitumor activity in patients with MM. We developed a population pharmacokinetics (PKs) model for mezigdomide in healthy subjects (HSs), and quantified effects of high-fat meal and proton pump inhibitor (PPI) on human disposition parameters. Plasma concentrations from 64 HS in two phase I clinical studies (NCT03803644 and NCT04211545) were used to develop a population PK model. The HSs received single oral doses of 0.4-3.2 mg mezigdomide with full PK profiles collected. A two-compartment linear PK model with first-order absorption and lag time best described mezigdomide PK profiles in HSs. The population PK parameters of absorption rate constant, lag time, central volume of distribution, clearance, peripheral volume of distribution, and intercompartmental clearance were estimated to be 1.18 h-1 (interoccasion variability [IOV]: 65%), 0.423 h (IOV: 31%), 440 L (interindividual variability [IIV]: 63%), 35.1 L/h (IIV: 40%), 243 L (IIV: 26%), and 36.8 L/h (IIV: 26%), respectively. High-fat meal increased oral bioavailability by ~30% and PPI co-administration decreased oral bioavailability by ~64%. Mezigdomide demonstrated a linear dose-exposure relationship in HSs. The PK model suggests a modest effect of high-fat meal, and a substantial effect of PPIs on mezigdomide oral bioavailability. This population PK model enables data integration across studies to identify important covariate effects and is being used to guide dose selection in clinical study designs for mezigdomide in patients with MM.

Targeting a xenobiotic transporter to ameliorate vincristine-induced sensory neuropathy.

Vincristine is a widely used chemotherapeutic drug for the treatment of multiple malignant diseases that causes a dose-limiting peripheral neurotoxicity. There is no clinically effective preventative treatment for vincristine-induced sensory peripheral neurotoxicity (VIPN), and mechanistic details of this side effect remain poorly understood. We hypothesized that VIPN is dependent on transporter-mediated vincristine accumulation in dorsal root ganglion neurons. Using a xenobiotic transporter screen, we identified OATP1B3 as a neuronal transporter regulating the uptake of vincristine. In addition, genetic or pharmacological inhibition of the murine orthologue transporter OATP1B2 protected mice from various hallmarks of VIPN - including mechanical allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes and neuronal morphology - without negatively affecting plasma levels or antitumor effects of vincristine. Finally, we identified α-tocopherol from an untargeted metabolomics analysis as a circulating endogenous biomarker of neuronal OATP1B2 function, and it could serve as a companion diagnostic to guide dose selection of OATP1B-type transport modulators given in combination with vincristine to prevent VIPN. Collectively, our findings shed light on the fundamental basis of VIPN and provide a rationale for the clinical development of transporter inhibitors to prevent this debilitating side effect.

Guiding model-driven combination dose selection using multi-objective synergy optimization.

Despite the growing appreciation that the future of cancer treatment lies in combination therapies, finding the right drugs to combine and the optimal way to combine them remains a nontrivial task. Herein, we introduce the Multi-Objective Optimization of Combination Synergy - Dose Selection (MOOCS-DS) method for using drug synergy as a tool for guiding dose selection for a combination of preselected compounds. This method decouples synergy of potency (SoP) and synergy of efficacy (SoE) and identifies Pareto optimal solutions in a multi-objective synergy space. Using a toy combination therapy model, we explore properties of the MOOCS-DS algorithm, including how optimal dose selection can be influenced by the metric used to define SoP and SoE. We also demonstrate the potential of our approach to guide dose and schedule selection using a model fit to preclinical data of the combination of the PD-1 checkpoint inhibitor pembrolizumab and the anti-angiogenic drug bevacizumab on two lung cancer cell lines. The identification of optimally synergistic combination doses has the potential to inform preclinical experimental design and improve the success rates of combination therapies. Jel classificationDose Finding in Oncology.

Levetiracetam Pharmacokinetics and Brain Uptake in a Lateral Fluid Percussion Injury Rat Model.

Post-traumatic epilepsy (PTE) occurs in some patients after moderate/severe traumatic brain injury (TBI). Although there are no approved therapies to prevent epileptogenesis, levetiracetam (LEV) is commonly given for seizure prophylaxis due to its good safety profile. This led us to study LEV as part of the Epilepsy Bioinformatics Study for Antiepileptogenic Therapy (EpiBioS4Rx) Project. The objective of this work is to characterize the pharmacokinetics (PK) and brain uptake of LEV in naïve control rats and in the lateral fluid percussion injury (LFPI) rat model of TBI after either single intraperitoneal doses or a loading dose followed by a 7-day subcutaneous infusion. Sprague-Dawley rats were used as controls and for the LFPI model induced at the left parietal region using injury parameters optimized for moderate/severe TBI. Naïve and LFPI rats received either a bolus injection (intraperitoneal) or a bolus injection followed by subcutaneous infusion over 7 days. Blood and parietal cortical samples were collected at specified time points throughout the study. LEV concentrations in plasma and brain were measured using validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) methods. Noncompartmental analysis and a naive-pooled compartmental PK modeling approach were used. Brain-to-plasma ratios ranged from 0.54 to 1.4 to 1. LEV concentrations were well fit by one-compartment, first-order absorption PK models with a clearance of 112 ml/h per kg and volume of distribution of 293 ml/kg. The single-dose pharmacokinetic data were used to guide dose selection for the longer-term studies, and target drug exposures were confirmed. Obtaining LEV PK information early in the screening phase allowed us to guide optimal treatment protocols in EpiBioS4Rx. SIGNIFICANCE STATEMENT: The characterization of levetiracetam pharmacokinetics and brain uptake in an animal model of post-traumatic epilepsy is essential to identify target concentrations and guide optimal treatment for future studies.

Development of a population pharmacokinetic model to characterize the pharmacokinetics of intrathecally administered tominersen in cerebrospinal fluid and plasma.

Tominersen is an intrathecally administered antisense oligonucleotide targeting huntingtin mRNA which leads to a dose-dependent, reversible lowering of cerebrospinal fluid (CSF) mutant huntingtin protein concentration in individuals with Huntington's disease. Nonlinear mixed-effect population pharmacokinetic (PopPK) modeling was conducted to characterize the CSF and plasma pharmacokinetics (PK) of tominersen, and to identify and quantify the covariates that affect tominersen PKs. A total of 750 participants from five clinical studies with a dose range from 10 to 120 mg contributed CSF (n = 6302) and plasma (n = 5454) PK samples. CSF PK was adequately described by a three-compartment model with first-order transfer from CSF to plasma. Plasma PK was adequately described by a three-compartment model with first-order elimination from plasma. Baseline total CSF protein, age, and antidrug antibodies (ADAs) were the significant covariates for CSF clearance. Body weight was a significant covariate for clearances and volumes in plasma. ADAs and sex were significant covariates for plasma clearance. The developed PopPK model was able to describe tominersen PK in plasma and CSF after intrathecal administration across a range of dose levels, and relevant covariate relationships were identified. This model has been applied to guide dose selection for future clinical trials of tominersen in patients with Huntington's disease.

Clearance as an Early Indicator of Efficacy for Therapeutic Monoclonal Antibodies: Circumventing Dose Selection Challenges in Oncology.

The designs of first-in-human (FIH) studies in oncology (e.g., 3+3 dose escalation design) usually do not provide a sufficient sample size to determine the dose-response relationship for efficacy. This study aimed to assess the feasibility of using monoclonal antibody (mAb) clearance as a biomarker for efficacy to facilitate the identification of potentially efficacious doses across cancer types and drug targets. We performed electronic searches of the Drugs@FDA website, the European Medicines Agency website, and PubMed to identify reports of FIH trials of approved mAbs in oncology. The clearance, half-life, and overall response rate (ORR) data for the mAbs at different dose levels were extracted. Twenty-five approved mAbs were included in this study. As expected, due to the small sample sizes in FIH studies, there was no clear dose-response for ORR. However, we found a clear negative association between mAb clearance and ORR across tumors/drug targets, and a clear negative dose-clearance relationship, with clearance decreasing and saturated at high dose levels. The approved mAb doses (1-25 mg/kg) are approximately 2-fold the saturation doses (1-10 mg/kg). The associated clearance values at the approved doses vary across different cancers and drug targets (0.17-1.56 L/day), while tend to be similar within a disease/drug target. Anti-CD20 mAbs for B-cell lymphomas show a higher clearance (~ 1 L/day) than other cancers and targets (e.g., ~0.3 L/day for anti-PD-1). Clearance of mAbs can be a tumor/drug target-agnostic biomarker for potential anti-tumor activity as clearance decreases with increasing ORR. Our findings shed important insights into target clearance values that may lead to desired efficacy for different cancers and drug targets, which can be used to guide dose selection for the future development of mAbs during FIH oncology studies.

Sex differences for antipsychotic dosing and how to guide therapy

AbstractOver the past decades the role of sex in the antipsychotic treatment type and dose selection has been virtually overseen. In fact, medication approval trials barely stratify for sex differences. Emerging hints from different types of data highlight the need for antipsychotic treatment personalization within the context of sex differences. Varying bioavaibility patterns of the prescribed antipsychotics between female and male patients may be easy to capture measuring plasma or serum levels of the antipsychotics ultimately guiding dose selection in clinical routine. Here we will discuss pitfalls and current evidence regarding sex affecting dose selection to enhance safety and effectiveness outcomes of antipsychotic treatment.Disclosure of InterestG. Schoretsanitis Consultant of: HLS Therapeutics and ThermoFisher

Standardized RS Ratio Metrics To Assess Tuberculosis Antimicrobial Efficacy and Potency.

The sigmoid Emax model was used to describe the rRNA synthesis ratio (RS ratio) response of Mycobacterium tuberculosis to antimicrobial concentration. RS-Emax measures the maximal ability of a drug to inhibit the RS ratio and can be used to rank-order drugs based on their RS ratio effect. RS-EC90 is the concentration needed to achieve 90% of the RS-Emax, which may guide dose selection to achieve a maximal RS ratio effect in vivo.

Genomic Adjusted Radiation Dose (GARD) Predicts Overall Survival and Outperforms AJCC 8th Edition in Prognostication of HPV-Positive Oropharyngeal Squamous Cell Carcinoma

<h3>Purpose/Objective(s)</h3> Treatment decision-making in oropharyngeal squamous cell carcinoma (OPSCC) includes clinical stage, HPV status, and smoking history. Despite improvements in staging with separation of HPV positive and negative OPSCC in AJCC 8^th edition (AJCC8), patients are largely treated with a uniform approach, with recent efforts on de-intensification in low-risk patients. We have previously shown, in a pooled analysis, that the genomic adjusted radiation dose (GARD) is predictive of radiation treatment benefit and can be used to guide dose selection. We hypothesize that GARD can be used to predict overall survival (OS) in HPV-positive OPSCC patients treated with radiotherapy (RT). <h3>Materials/Methods</h3> Gene expression profiles were analyzed for 234 formalin-fixed paraffin-embedded samples from HPV-positive OPSCC patients within an international, multi-institutional, prospective/retrospective observational study (Big Data and Models for Personalized Head and Neck Cancer Decision Support (BD2Decide, NCT02832102). GARD, a measure of the biological effect of RT, was calculated for each patient as previously described. In total, 203 patients received definitive treatment (chemoradiation or RT alone), and 31 patients received post-operative RT. Two RT dose fractionations were utilized for definitive cases (70 Gy in 35 fractions or 69.96 Gy in 33 fractions). Median RT dose was 70 Gy (mean 50.88-74) for definitive cases and 66 Gy (range 44-70) for post-operative cases. 29 patients received surgery and adjuvant chemoradiation, 14 received surgery and adjuvant RT, and 19 received RT alone. The median follow up was 46.2 months (95% CI, 41.2 to 50). Cox proportional hazards analyses were performed with GARD as a continuous variable and ROC analyses comparing the performance of GARD with AJCC8. <h3>Results</h3> Despite uniform radiation dose utilization, GARD showed significant heterogeneity (range 30-110), reflecting the underlying genomic differences in the cohort. On multivariate analysis, each unit increase in GARD was associated with an improvement in OS (HR= 0.97, 95% CI 0.94-1.0, p=0.040) compared to AJCC8 (HR=1.96, 95% CI 0.90-4.32, p=0.0952). ROC analysis for GARD at 24 months yielded an AUC of 75.6 (95% CI 61.8-89.4) compared with an AUC of 73.9 (95% CI 56.9-90.9) for AJCC8. GARD ≥64.97 was associated with improved OS (HR=0.29, p=0.005). <h3>Conclusion</h3> In this multi-institutional cohort of patients with HPV-positive OPSCC, GARD predicts OS as a continuous variable and outperforms AJCC8 in prognostication. We propose that GARD, which provides the first opportunity for genomic guided personalization of radiation dose, should be incorporated in the diagnostic workup of HPV-positive OPSCC patients and can be used to guide treatment decision making.

Assessment of KRAS G12C Target Engagement by a Covalent Inhibitor in Tumor Biopsies Using an Ultra-Sensitive Immunoaffinity 2D-LC–MS/MS Approach

KRAS is one of the most frequently mutated oncogenes, with KRAS G12C recently becoming an actionable target for small molecule intervention. GDC-6036 is an investigational KRAS G12C inhibitor that acts by irreversibly binding to the switch II pocket of KRAS G12C when in the inactive GDP-bound state, thereby blocking GTP binding and activation. Assessing target engagement is an essential component of clinical drug development, helping to demonstrate mechanistic activity, guide dose selection, understand pharmacodynamics as it relates to clinical response, and explore resistance. Here, we report the development of an ultra-sensitive approach for assessing KRAS G12C engagement. Immunoaffinity enrichment with a commercially available anti-RAS antibody was combined with a targeted 2D-LC-MS/MS technique to quantify both free and GDC-6036-bound KRAS G12C proteins. A KRAS G12C-positive non-small cell lung cancer xenograft model was dosed with GDC-6036 to assess the feasibility of this assay for analyzing small core needle biopsies. As predicted, dose-dependent KRAS G12C engagement was observed. To date, a sensitivity of 0.08 fmol/μg of total protein has been achieved for both free and GDC-6036-bound KRAS G12C with as little as 4 μg of total protein extracted from human tumor samples. This sub-fmol/μg level of sensitivity provides a powerful potential approach to assess covalent inhibitor target engagement at the site of action using core needle tumor biopsies from clinical studies.

An Investigational Inhaled rhIL-1Ra (ALTA-2530) Demonstrates Distribution to Distal Regions of Lung and High Affinity IL-1 Receptor Blockade Supporting Development as a Treatment for Bronchiolitis Obliterans Syndrome

<h3>Purpose</h3> Dysregulated expression of interleukin-1 (IL-1), and downstream cytokines including IL-6, has been implicated in the development and progression of bronchiolitis obliterans syndrome (BOS). Quiescence of IL-1 signaling via blockade of the IL-1 receptor type 1 (IL-1R1) is proposed to restore physiologic immune regulation. Herein, we characterize ALTA-2530: i) distribution in rat and non-human primate (NHP) lung tissue following aerosolized administration, ii) binding affinity to IL-1R1, and iii) <i>in vitro</i> suppression of IL-6 release to assess potency of receptor blockade and development of an exposure response relationship to guide dose selection for <i>in vivo</i> studies. <h3>Methods</h3> Bronchoalveolar lavage fluid (BALF) and lung tissue samples were collected from rat and NHP following 7 daily inhaled doses of ALTA-2530. ALTA-2530 was determined in BALF by affinity capture LC-MS/MS. Tissues were processed for immunohistochemistry to identify the distribution of rhIL-1Ra. Binding kinetics of rhIL-1Ra to human IL-1R1 were determined by surface plasmon resonance and compared to IL-1α and β. ALTA-2530 mediated inhibition of IL-6 release in human and NHP whole blood was determined following stimulation by IL-1β. <h3>Results</h3> Once daily administration of ALTA-2530 provided >24hr exposure in BALF. Immunohistochemistry of lungs from healthy rats and NHPs 24hr post dose demonstrated dose-dependent delivery of ALTA-2530 to alveoli and bronchial epithelial cells. Early data also indicate association with alveolar macrophages. Distribution to narrow rat bronchioles is supportive of therapeutically relevant distribution in human bronchioles - a target for the treatment of BOS. ALTA-2530 rhIL-1Ra bound to IL-1R1 with over 100X greater affinity (K_D∼10⁻¹² M, k_d∼10⁻⁵ s⁻¹, k_a∼10⁶ M⁻¹s⁻¹) than endogenous IL-1 agonists IL-1α (K_D∼10⁻⁷ M, k_d∼10⁻³ s⁻¹, k_a∼10³ M⁻¹s⁻¹) and IL-1β (K_D∼10⁻¹⁰ M, k_d∼10⁻³ s⁻¹, k_a∼10⁷ M⁻¹s⁻¹). Functional potency for IL-1R1 blockade in whole blood demonstrated ALTA-2530 rhIL-1Ra potently inhibited IL-6 release following IL-1β stimulation (human IC₅₀ 5 ng/mL; NHP IC₅₀ 7 ng/mL). <h3>Conclusion</h3> Inhaled ALTA-2530 distributes to distal regions of lung and inhibits IL-6 release supportive of a therapy for IL-1 and IL-6 driven pathologies including BOS.

The effects of different doses of inhaled bacteriophage therapy for Pseudomonas aeruginosa pulmonary infections in mice

ObjectivesInhaled phage therapy has been revisited as a potential treatment option for respiratory infections caused by multidrug-resistant Pseudomonas aeruginosa; however, there is a distinct gap in understanding the dose–response effect. The aim of this study was to investigate the dose–response effect of Pseudomonas-targeting phage PEV31 delivered by the pulmonary route in a mouse lung infection model. MethodsNeutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 104 colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 104 (Group A), 5 × 106 (Group B), and 5 × 108 (Group C) plaque-forming units, or phosphate-buffered saline at 2 hours postinoculation. Mice (n = 5–7) were euthanized at 2 hours and 24 hours postinfection, and lungs, kidneys, spleen, liver, bronchoalveolar lavage fluid, and blood were collected for bacteria and phage enumeration. ResultsAt 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3–1.9 log10, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log10 titre increases of 6.2, 2.7, and 9 for Groups A, B, and C, respectively. Phage-resistant bacterial subpopulations in the lung homogenate samples harvested at 24 hours postinfection increased with the treatment dose (i.e. 30%, 74%, and 91% in respective Groups A–C). However, the mutants showed increased susceptibility to ciprofloxacin, impaired twitching motility, and reduced blue-green pigment production. The expression of the inflammatory cytokines (IL-1ß and IL-6, and TNF-α) was suppressed with increasing PEV31 treatment dose. DiscussionThis study provides the dose–response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.

P.0461 Population pharmacokinetic modeling and simulation to guide dose selection for TV-46000, a new long-acting formulation of risperidone for subcutaneous injection

P.0461 Population pharmacokinetic modeling and simulation to guide dose selection for TV-46000, a new long-acting formulation of risperidone for subcutaneous injection