Phase 1 study of safety and tolerability of an oral contraceptive containing low-dose ethinyl oestradiol combined with glecaprevir/pibrentasvir treatment in healthy premenopausal women.

Glecaprevir/pibrentasvir (GLE/PIB) is an approved guideline-recommended chronic hepatitis C virus infection treatment. GLE/PIB coadministration with ethinyl oestradiol (EE) is not recommended in current labels owing to a Phase 1 study observing Grade ≥2 alanine aminotransferase (ALT) elevation in 2 out of 12 healthy women cotreated for 11 days with GLE/PIB and oral contraceptive (OC) containing 35 µg/250 µg EE/norgestimate. No Grade ≥2 elevation was observed with low-dose (20 µg) EE (n = 14). This Phase 1 study examined safety/tolerability of GLE/PIB coadministered with an OC containing low-dose EE using a larger sample size and longer treatment duration. Healthy premenopausal women were treated with EE/levonorgestrel alone (20/100 µg, Cycles 1-2), followed by coadministration with GLE/PIB (300/120 mg; Cycles 3-4). A safety criterion of special interest was a confirmed Grade ≥2 ALT elevation (>3× upper normal limit). Adverse events (AEs) and study drugs concentrations were examined. Of 85 enrolled women, 72 initiated combined GLE/PIB + EE/levonorgestrel treatment, 66 completed the study and 19 discontinued prematurely (non-safety reason, n = 16; AE [deemed unelated to GLE/PIB], n = 3). No participant met the safety criterion of special interest of confirmed Grade ≥2 ALT elevation. No serious/Grade ≥3 AEs were reported. Study drug concentrations were within the expected ranges. GLE/PIB in combination with an OC containing low-dose EE was generally well tolerated with no confirmed Grade ≥2 ALT elevation and no evidence of drug-induced liver injury. No pattern to the reported AEs and no new safety issues were identified. This was a Phase 1 study of healthy volunteers, not a registered clinical trial.

Higher vs Standard Adalimumab Induction and Maintenance Dosing Regimens for Treatment of Ulcerative Colitis: SERENE UC Trial Results.

BACKGROUND & AIMS: SERENE UC (Study of a Novel Approach to Induction and Maintenance Dosing With Adalimumab in Patients With Moderate to Severe Ulcerative Colitis) evaluated the efficacy of higher adalimumab induction and maintenance dose regimens in patients with ulcerative colitis. METHODS: This phase 3, double-blind, randomized trial included induction and maintenance studies, with a main study (ex-Japan) and Japan substudy. Eligible patients (18-75 years, full Mayo score 6-12, centrally read endoscopy subscore 2-3) were randomized 3:2 to higher induction regimen (adalimumab 160 mg at weeks 0, 1, 2, and 3) or standard induction regimen (160 mg at week 0 and 80 mg at week 2); all received 40 mg at weeks 4 and 6. At week 8, all patients were rerandomized 2:2:1 (main study) to 40 mg every week (ew), 40 mg every other week (eow), or exploratory therapeutic drug monitoring; or 1:1 (Japan substudy) to 40 mg ew or 40 mg eow maintenance regimens. RESULTS: In the main study, 13.3% vs 10.9% of patients receiving the higher induction regimen vs standard induction regimen achieved clinical remission (full Mayo score ≤2 with no subscore >1) at week 8 (induction primary end point; P = .265); among week-8 responders, 39.5% vs 29.0% receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (maintenance primary end point; P = .069). In the integrated (main + Japan) population, 41.1% vs 30.1% of week-8 responders receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (nominal P = .045). Safety profiles were comparable between dosing regimens. CONCLUSION: Although primary end points were not met, a >10% absolute difference in clinical remission was demonstrated with higher adalimumab maintenance dosing. Higher dosing regimens were generally well tolerated and consistent with the known safety profile of adalimumab in ulcerative colitis. CLINICALTRIALS: gov, Number: NCT002209456.

Higher vs Standard Adalimumab Induction Dosing Regimens and Two Maintenance Strategies: Randomized SERENE CD Trial Results.

BACKGROUND & AIMS: Dose-optimization strategies for biologic therapies in Crohn's disease (CD) are not well established. The SERENE CD (Study of a Novel Approach to Induction and Maintenance Dosing With Adalimumab in Patients With Moderate to Severe Crohn's Disease) trial evaluated higher vs standard adalimumab induction dosing and clinically adjusted (CA) vs therapeutic drug monitoring (TDM) maintenance strategies in patients with moderately to severely active CD. METHODS: In this phase 3, randomized, double-blind, multicenter trial, eligible adults (Crohn's Disease Activity Index score of 220-450, endoscopic evidence of mucosal inflammation, and previous failure of standard therapies) were randomized to higher induction regimen (adalimumab 160 mg at weeks 0, 1, 2, and 3; n = 308) or standard induction regimen (adalimumab 160 mg at week 0 and 80 mg at week 2; n = 206) followed by 40 mg every other week from week 4 onward. Co-primary end points included clinical remission at week 4 and endoscopic response at week 12. At week 12, patients were re-randomized to maintenance therapy optimized by Crohn's Disease Activity Index and C-reactive protein (CA; n = 92) or serum adalimumab concentrations and/or clinical criteria (TDM; n = 92); exploratory end points were evaluated at week 56. RESULTS: Similar proportions of patients receiving higher induction regimen and standard induction regimen achieved clinical remission at week 4 (44% in both; P = .939) and endoscopic response at week 12 (43% vs 39%, respectively, P = .462). Week 56 efficacy was similar between CA and TDM. Safety profiles were comparable between dosing regimens. CONCLUSIONS: Higher induction regimen was not superior to standard induction regimen, and CA and TDM maintenance strategies were similarly efficacious. Adalimumab therapy was well tolerated, and no new safety concerns were identified. (ClinicalTrials.gov, Number: NCT02065570).

Interdisciplinary model-informed drug development for extending duration of elagolix treatment in patients with uterine fibroids.

AIM: Elagolix, a gonadotropin-releasing hormone receptor antagonist, was recently approved for heavy menstrual bleeding associated with uterine fibroids (UF, Oriahnn) at a dose of 300 mg twice daily (BID) in combination with add-back therapy (oestradiol 1 mg/norethindrone acetate 0.5 mg [E2/NETA] once daily) for 24 months use. The limited duration of treatment is related to elagolix dose- and duration-dependent decrease in oestrogen that is mechanistically linked to changes in bone mineral density (BMD). The work herein supported the extended treatment duration of 24 months. METHODS: An integrated exposure-response and epidemiological modelling framework of elagolix effects on femoral neck BMD (FN-BMD), informed by real-world data and phase 3 clinical trials data, was developed to predict the time course and magnitude of changes in BMD and its relation to risk of bone fracture in women with UF. RESULTS: Model results indicated that women treated with elagolix 300 mg BID + E2/NETA in the long term (ie, >24 months) may experience less than 1% loss in FN-BMD per year, relative to placebo. The exposure-response model simulations and clinical risk factors were used to estimate 10-year risk of fractures using the clinically validated Fracture Risk Assessment Tool (FRAX). The impact of elagolix 300 mg BID + E2/NETA treatment on the 10-year risk of hip or major osteoporotic fractures estimated from the FRAX model was minimal compared to that of placebo. CONCLUSION: The elagolix integrated exposure-BMD analysis and translation to fracture risk provided an interdisciplinary model-informed drug development framework for clinical benefit-risk evaluation and enabled approval of longer treatment duration to benefit the patient.

Efficacy and safety of continuing versus withdrawing adalimumab therapy in maintaining remission in patients with non-radiographic axial spondyloarthritis (ABILITY-3): a multicentre, randomised, double-blind study.

BACKGROUND: Success of treatment withdrawal in patients with non-radiographic axial spondyloarthritis who are in remission remains unknown. The ABILITY-3 study explored the ability to withdraw adalimumab treatment in patients with non-radiographic axial spondyloarthritis who achieved sustained clinical remission after open-label treatment with adalimumab. METHODS: ABILITY-3 was a multicentre, two-period study done in 107 sites in 20 countries. We enrolled adult patients (≥18 years) diagnosed with non-radiographic axial spondyloarthritis, fulfilling Assessment of SpondyloArthritis international Society classification criteria but not the modified New York radiologic criterion, who had objective evidence of active inflammation, active disease, and inadequate response to at least two non-steroidal anti-inflammatory drugs. Patients who achieved Ankylosing Spondylitis Disease Activity Score (ASDAS) inactive disease (<1·3) with open-label adalimumab (40 mg subcutaneously every other week for 28 weeks) at weeks 16, 20, 24, and 28 were randomly assigned (1:1) using an interactive voice or web response system to 40-week, double-blind treatment with adalimumab (continuation) or placebo (withdrawal). The primary efficacy endpoint was the proportion of patients who did not experience a flare (defined as ASDAS ≥2·1 at two consecutive visits) during the double-blind period. Patients who flared were rescued with open-label adalimumab. This study is registered with ClinicalTrials.gov, number NCT01808118. FINDINGS: Between June 27, 2013, and October 22, 2015, 673 patients were enrolled to the study. The trial completed on April 14, 2017. Of 673 enrolled patients, 305 (45%) achieved sustained remission and were randomly assigned to double-blind treatment (152 patients to adalimumab and 153 to placebo). A greater proportion of patients continuing adalimumab than those receiving placebo did not experience a flare (107 [70%] of 152 patients vs 72 [47%] of 153 patients; p<0·0001) up to and including week 68. Among 673 patients receiving adalimumab at any time, 516 (77%) patients reported an adverse event and 28 (4%) experienced a serious adverse event. The most common adverse events in both the adalimumab and placebo groups were nasopharyngitis (25 [16%] vs 20 [13%]), upper respiratory tract infection (20 [13%] vs 12 [8%]), and worsening of axial spondyloarthritis (ten [7%] vs 21 [14%]). INTERPRETATION: In patients with active non-radiographic axial spondyloarthritis who achieved sustained remission with adalimumab, continued therapy was associated with significantly fewer patients flaring than was treatment withdrawal. FUNDING: AbbVie.

Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa.

BACKGROUND: Hidradenitis suppurativa is a painful, chronic inflammatory skin disease with few options for effective treatment. In a phase 2 trial, adalimumab, an antibody against tumor necrosis factor α, showed efficacy against hidradenitis suppurativa. METHODS: PIONEER I and II were similarly designed, phase 3 multicenter trials of adalimumab for hidradenitis suppurativa, with two double-blind, placebo-controlled periods. In period 1, patients were randomly assigned in a 1:1 ratio to 40 mg of adalimumab weekly or matching placebo for 12 weeks. In period 2, patients were reassigned to adalimumab at a weekly or every-other-week dose or to placebo for 24 weeks. The primary end point was a clinical response, defined as at least a 50% reduction from baseline in the abscess and inflammatory-nodule count, with no increase in abscess or draining-fistula counts, at week 12. RESULTS: We enrolled 307 patients in PIONEER I and 326 in PIONEER II. Clinical response rates at week 12 were significantly higher for the groups receiving adalimumab weekly than for the placebo groups: 41.8% versus 26.0% in PIONEER I (P=0.003) and 58.9% versus 27.6% in PIONEER II (P<0.001). Patients receiving adalimumab had significantly greater improvement than the placebo groups in rank-ordered secondary outcomes (lesions, pain, and the modified Sartorius score for disease severity) at week 12 in PIONEER II only. Serious adverse events in period 1 (excluding worsening of underlying disease) occurred in 1.3% of patients receiving adalimumab and 1.3% of those receiving placebo in PIONEER I and in 1.8% and 3.7% of patients, respectively, in PIONEER II. In period 2, the rates of serious adverse events were 4.6% or less in all the groups in both studies, with no significant between-group differences. CONCLUSIONS: Treatment with adalimumab (40 mg weekly), as compared with placebo, resulted in significantly higher clinical response rates in both trials at 12 weeks; rates of serious adverse events were similar in the study groups. (Funded by AbbVie; ClinicalTrials.gov numbers, NCT01468207 and NCT01468233 for PIONEER I and PIONEER II, respectively.).

Determining the optimal dose of atrasentan by evaluating the exposure-response relationships of albuminuria and bodyweight.

This study aimed to identify the optimal dose of the endothelin-1 receptor antagonist atrasentan with maximal albuminuria reduction and minimal signs of sodium retention, as manifested by increase in bodyweight. Data from the RADAR-JAPAN studies were used, evaluating the effect of 0.75 or 1.25 mg/d of atrasentan in 161 patients with type 2 diabetes and kidney disease. Individual pharmacokinetic parameters were estimated using a population pharmacokinetic approach. Subsequently, changes in the urinary albumin-to-creatinine ratio (UACR) and bodyweight from baseline after 2 weeks' exposure were modelled as a function of the pharmacokinetic parameters. The 0.75 and 1.25 mg doses showed a mean UACR reduction of 34.0% and 40.1%, whereas mean bodyweight increased by 0.9 and 1.1 kg, respectively. A large variation between individuals was observed in the UACR and bodyweight responses. Individual pharmacokinetic parameters correlated significantly with both individual UACR and bodyweight responses (P < .01). The individual response curves for UACR and bodyweight crossed at approximately the mean trough concentration of 0.75 mg atrasentan, indicating that 0.75 mg/d of atrasentan is the optimal dose for kidney protection with maximal efficacy (albuminuria reduction) and safety (minimal sodium retention).

Veliparib in combination with whole brain radiation therapy in patients with brain metastases: results of a phase 1 study.

Veliparib, a potent, oral PARP inhibitor, potentiates the antitumor activity of radiation therapy and crosses the blood-brain barrier. This was a phase 1 dose-escalation study evaluating the safety, and secondarily the antitumor activity of veliparib in combination with whole brain radiation therapy (WBRT) in patients with brain metastases, in order to power future trials. Patients with brain metastases from primary solid tumors were treated with WBRT (30.0 or 37.5 Gy in 10 or 15 fractions) and veliparib (escalating doses of 10-300 mg, orally BID). Safety and tumor response were assessed. Observed survival was compared to predicted survival based on a published nomogram. Eighty-one patients (median age 58 years) were treated. The most common primary tumor types were non-small cell lung (NSCLC; n = 34) and breast cancer (n = 25). The most common AEs deemed possibly related to veliparib (AEs, ≥15 %) were fatigue (30 %), nausea (22 %), and decreased appetite (15 %). Fatigue (5 %), hypokalemia and hyponatremia (3 % each) were the only Grade 3/4 AEs deemed possibly related to veliparib observed in ≥2 patients. Although this was an uncontrolled study, preliminary efficacy results were better than predicted: the median survival time (MST, 95 % CI) for the NSCLC subgroup was 10.0 mo (3.9-13.5) and for the breast cancer subgroup was 7.7 mo (2.8-15.0) compared to a nomogram-model-predicted MST of 3.5 mo (3.3-3.8) and 4.9 mo (4.2-5.5). The addition of veliparib to WBRT did not identify new toxicities when compared to WBRT alone. Based on encouraging safety and preliminary efficacy results, a randomized, controlled phase 2b study is ongoing.

Bioequivalence of Elagolix/Estradiol/Norethindrone Acetate Fixed-Dose Combination Product: Phase 1 Results in Healthy Pre- and Postmenopausal Women.

Fixed-dose combination (FDC) therapies can enhance patient convenience and adherence to prescribed treatment regimens. Elagolix is a novel oral gonadotropin-releasing hormone receptor antagonist approved for management of moderate to severe pain associated with endometriosis and heavy menstrual bleeding associated with uterine fibroids. Hormonal add-back therapy can attenuate the reversible hypoestrogenic effects of elagolix. An FDC formulation containing elagolix/estradiol (E2)/norethindrone acetate (NETA) 300/1/0.5 mg as the morning dose and an elagolix 300 mg capsule as the evening dose, were evaluated in 2 bioequivalence studies including the effects of food. Study 1 in premenopausal women assessed the bioavailability of the elagolix 300-mg capsule relative to the commercially available elagolix 300-mg tablet. Study 2 in postmenopausal women, elagolix/E2/NETA (300 mg/1 mg/0.5 mg) FDC capsule was assessed relative to the elagolix 300-mg tablet coadministered with E2/NETA 1-mg/0.5-mg tablet, the regimen that was studied in Phase 3 uterine fibroid studies. Under fasting conditions, the test elagolix 300-mg capsule was bioequivalent to the reference elagolix 300-mg tablet. Under fasting conditions, the elagolix/E2/NETA FDC capsule was bioequivalent to the coadministered elagolix 300-mg tablet and E2/NETA 1/0.5-mg tablet. Following administration of elagolix/E2/NETA FDC capsule after a high-fat breakfast, elagolix mean maximum concentration (Cmax) and area under the plasma concentration-time curve (AUC) were 38% and 28% lower, relative to fasting conditions. NETA mean Cmax was 51% lower and AUC from time 0 to infinity was 20% higher, while baseline-adjusted total estrone mean Cmax and AUC were 46% and 14% lower, respectively. No safety concerns were identified. These results enabled bridging the elagolix/E2/NETA FDC capsule.

SERENE ER Analysis Part 1-SERENE CD: Exposure-Response Analysis of Higher Versus Standard Adalimumab Dosing Regimens for Patients With Moderately to Severely Active Crohn Disease.

SERENE CD (NCT02065570) evaluated whether a higher adalimumab induction dose would improve patients with Crohn disease response and suggested a flat dose-response relationship for efficacy in the induction study. We investigated exposure-response relationships in induction and maintenance studies considering patients' baseline characteristics. Adalimumab exposures were simulated using the established population pharmacokinetic model. Efficacy end points (clinical remission/endoscopic response) at Weeks 4, 12, and 56 were evaluated in exposure-response analyses using multivariable logistic regression. Analyses showed an increasing trend with heterogeneity between induction regimens, which suggested that average concentration has an impact on coprimary efficacy end points within each group, but data did not fit a single-response curve. Although higher concentrations within arms were associated with improved outcomes, increasing the concentration through a higher induction dose was not associated with increasing clinical remission/endoscopic response at Week 4/12. A model including inverse effective clearance eliminated heterogeneity and described trends across induction regimens with a single curve. In the maintenance study, the response rates at Week 56 showed no heterogeneity. In the induction study, patients with lower effective adalimumab clearance responded better, whereas in the maintenance study average concentration drove primary efficacy end points at Week 56. Research extending these findings to other indications is needed.

SERENE ER Analysis Part 2 SERENE-UC: Exposure-response Analysis of Higher Versus Standard Adalimumab Dosing Regimens for Patients with Moderately to Severely Active Ulcerative Colitis.

SERENE UC (NCT02065622) evaluated whether a higher adalimumab induction regimen improved patients with ulcerative colitis (UC) response, but a flat dose-response relationship was found in the induction study. We investigated exposure-response (ER) relationships in induction and maintenance studies considering patients' baseline characteristics. Adalimumab exposures were simulated using the established population pharmacokinetic model. Multivariable logistic regressions were used to assess the efficacy endpoints (clinical remission, endoscopic remission, endoscopic improvement) at weeks 8 and 52. In the induction study, an increasing ER trend with heterogeneity between induction regimens was shown, suggesting average concentration (Cavg) had a significant impact on primary efficacy endpoints within each group. However, data were not described by a single ER curve. Using inverse effective clearance as the exposure metric described trends across induction regimens with a single curve. Patients with inherently lower effective adalimumab clearance responded better. The patient response rates at week 52 showed no heterogeneity. A short-term increase in adalimumab dose did not drive better responses for induction, and apparent ER relationships were better explained by patient-inherent lower clearance. Conversely, during maintenance up to week 52, increasing the concentration via dose translated to better responses more robustly. The ER findings for SERENE UC were consistent with SERENE CD.

Assessment of Drug-Drug Interaction Risk Between Intravenous Fentanyl and the Glecaprevir/Pibrentasvir Combination Regimen in Hepatitis C Patients Using Physiologically Based Pharmacokinetic Modeling and Simulations.

INTRODUCTION: An unsafe injection practice is one of the major contributors to new hepatitis C virus (HCV) infections; thus, people who inject drugs are a key population to prioritize to achieve HCV elimination. The introduction of highly effective and well-tolerated pangenotypic direct-acting antivirals, including glecaprevir/pibrentasvir (GLE/PIB), has revolutionized the HCV treatment landscape. Glecaprevir is a weak cytochrome P450 3A4 (CYP3A4) inhibitor, so there is the potential for drug-drug interactions (DDIs) with some opioids metabolized by CYP3A4, such as fentanyl. This study estimated the impact of GLE/PIB on the pharmacokinetics of intravenous fentanyl by building a physiologically based pharmacokinetic (PBPK) model. METHODS: A PBPK model was developed for intravenous fentanyl by incorporating published information on fentanyl metabolism, distribution, and elimination in healthy individuals. Three clinical DDI studies were used to verify DDIs within the fentanyl PBPK model. This model was integrated with a previously developed GLE/PIB PBPK model. After model validation, DDI simulations were conducted by coadministering GLE 300 mg + PIB 120 mg with a single dose of intravenous fentanyl (0.5 µg/kg). RESULTS: The predicted maximum plasma concentration ratio between GLE/PIB + fentanyl and fentanyl alone was 1.00, and the predicted area under the curve ratio was 1.04, suggesting an increase of only 4% in fentanyl exposure. CONCLUSION: The administration of a therapeutic dose of GLE/PIB has very little effect on the pharmacokinetics of intravenous fentanyl. This negligible increase would not be expected to increase the risk of fentanyl overdose beyond the inherent risks related to the amount and purity of the fentanyl received during recreational use.

Assessing the Impact of Immunogenicity and Improving Prediction of Trough Concentrations: Population Pharmacokinetic Modeling of Adalimumab in Patients with Crohn's Disease and Ulcerative Colitis.

BACKGROUND AND OBJECTIVE: Predicting adalimumab pharmacokinetics (PK) for patients impacted by anti-drug antibodies (ADA) has been challenging. The present study assessed the performance of the adalimumab immunogenicity assays in predicting which patients with Crohn's disease (CD) and ulcerative colitis (UC) have low adalimumab trough concentrations; and aimed to improve predictive performance of adalimumab population PK (popPK) model in CD and UC patients whose PK was impacted by ADA. METHODS: Adalimumab PK and immunogenicity data obtained from 1459 patients in SERENE CD (NCT02065570) and SERENE UC (NCT02065622) were analyzed. Adalimumab immunogenicity was assessed using electrochemiluminescence (ECL) and enzyme-linked immunosorbent (ELISA) assays. From these assays, three analytical approaches (ELISA concentrations, titer, and signal-to-noise [S/N] measurements) were tested as predictors for classifying patients with/without low concentrations potentially affected by immunogenicity. The performance of different thresholds for these analytical procedures was assessed using receiver operating characteristic curves and precision-recall curves. Based on the results from the most sensitive immunogenicity analytical procedure, patients were classified into PK-not-ADA-impacted and PK-ADA-impacted subpopulations. Stepwise popPK modeling was implemented to fit the PK data to an empirical adalimumab two-compartment model with linear elimination and ADA delay compartments to account for the time delay to generate ADA. Model performance was assessed by visual predictive checks and goodness-of-fit plots. RESULTS: The classical ELISA-based classification (with 20 ng/mL ADA as lower threshold) showed a good balance of precision and recall, to determine which patients had at least 30% adalimumab concentrations below 1 µg/mL. Titer-based classification with the lower limit of quantitation (LLOQ) as threshold showed higher sensitivity to classify these patients compared to the ELISA-based approach. Therefore, patients were classified as PK-ADA-impacted or PK-not-ADA impacted using the LLOQ titer threshold. In the stepwise modeling approach ADA-independent parameters were first fit using PK data from titer-PK-not-ADA-impacted population. The identified ADA-independent covariates included the effect of indication, weight, baseline fecal calprotectin, baseline C-reactive protein, baseline albumin on clearance; and sex and weight on volume of distribution of the central compartment. Pharmacokinetic-ADA-driven dynamics were characterized using PK data for the PK-ADA-impacted population. The categorical covariate based on the ELISA classification was the best at describing the additional effect of immunogenicity analytical approaches on ADA synthesis rate. The model was able to adequately describe the central tendency and variability for PK-ADA-impacted CD/UC patients. CONCLUSIONS: The ELISA assay was found to be optimal for capturing impact of ADA on PK. The developed adalimumab popPK model is robust in predicting PK profiles for CD and UC patients whose PK was impacted by ADA.

Therapeutic Development in Polyarticular Course Juvenile Idiopathic Arthritis: Extrapolation, Dose Selection, and Clinical Trial Design.

OBJECTIVE: Stakeholders met to address persistent challenges facing the development of therapeutics for polyarticular juvenile idiopathic arthritis (pJIA), which result in fewer approved therapies for children with pJIA than adults with rheumatoid arthritis (RA) and long lag times from adult RA approval to pediatric labeling. Ensuring that new medications are authorized in a timely manner to meet the needs of JIA patients worldwide is critically important to multiple stakeholders. METHODS: The Food and Drug Administration in collaboration with the University of Maryland Center for Regulatory Science and Innovation held a public workshop entitled "Accelerating Drug Development for pJIA" on October 2, 2019, to address challenges surrounding access to new medications for children and adolescents with pJIA. Regulatory, academic, and industry stakeholders, as well as patient representatives, participated in the workshop, which consisted of 4 sessions, including panel discussions. RESULTS: The workshop facilitated broad public discussion of challenges facing the development of pJIA therapeutics, highlighting areas of need and outlining opportunities to expedite development, while underscoring the necessity of close collaboration between all stakeholders, including patients and families. CONCLUSION: This report summarizes key aspects of the workshop, including the appropriate application of innovative approaches to the development of pJIA therapeutics, including extrapolation, to address current challenges and provide timely access to newer safe and effective treatments. Long-term safety assessment is of pressing concern to stakeholders and cannot be fully extrapolated from adult studies but requires consistent postmarketing long-term follow-up.

Effects of elagolix on the pharmacokinetics of omeprazole and its metabolites in healthy premenopausal women.

This study evaluated the effect of repeated doses of elagolix on the pharmacokinetics (PK) of omeprazole and its metabolites in healthy premenopausal female subjects. Adult premenopausal female subjects (N = 20) received a single oral dose of omeprazole (40 mg) on day 1 and day 11 and oral doses of elagolix (300 mg) twice-daily on days 3-11. Serial blood samples for assay of omeprazole and its metabolites were collected for 24 h after dosing on days 1 and 11. PK parameters were calculated for omeprazole, 5-hydroxyomeprazole and omeprazole sulfone; and were compared between day 1 and day 11. Pharmacogenetic testing was performed for CYP2C19 variant alleles and the results were used to compare the magnitude of elagolix-omeprazole drug-drug interaction (DDI) between the different genotype subgroups. Administration of elagolix 300 mg twice-daily for 9 days increased omeprazole exposure by 1.8-fold and decreased the metabolite-to-parent ratio for 5-hydroxyomeprazole by ~60%. Conversely, there was an increase in the metabolite-to-parent ratio for omeprazole sulfone by 25%. Elagolix increased omeprazole exposures by 2- to 2.5-fold in CYP2C19 extensive (EM) and intermediate (IM) metabolizer subjects, but decreased omeprazole exposures by 40% in poor metabolizer subjects. Exposures of 5-hydroxyomeprazole decreased by 20%-30% in all genotype subgroups, and omeprazole sulfone exposures increased by ~3-fold in EM and IM subjects. Elagolix is a weak inhibitor of CYP2C19 and exposure of CYP2C19 substrates may be increased upon coadministration with elagolix. Omeprazole may exhibit drug interactions due to multiple mechanisms other than CYP2C19-mediated metabolism; complicating the interpretation of results from omeprazole DDI studies.

Population Pharmacokinetics of Elagolix in Combination with Low-Dose Estradiol/Norethindrone Acetate in Women with Uterine Fibroids.

BACKGROUND AND OBJECTIVES: Elagolix is an orally active, gonadotropin-releasing hormone receptor antagonist approved for the management of endometriosis-associated pain and heavy menstrual bleeding associated with uterine fibroids. Elagolix population pharmacokinetics and factors affecting elagolix exposure in healthy women and women with endometriosis have been reported previously. The purpose of this study was to extend the population pharmacokinetics model with additional modifications to incorporate data from phase III studies of elagolix with hormonal add-back therapy in women with uterine fibroids. METHODS: Data from 13 clinical studies (a total of 2168 women) consisting of six phase I studies in healthy premenopausal women, four phase III studies in premenopausal women with endometriosis, and three phase III studies in premenopausal women with uterine fibroids were analyzed using a non-linear mixed-effects modeling approach. RESULTS: Elagolix population pharmacokinetics was best described by a two-compartment model with first-order absorption, lag time in absorption, and first-order elimination. Out of the covariates tested on elagolix apparent clearance, apparent volume of distribution, and/or relative bioavailability, only organic anion transporting polypeptide 1B1 genotype status and body weight had a statistically significant but no clinically meaningful effect on elagolix relative bioavailability and apparent volume of distribution, respectively. There were no clinically meaningful differences in elagolix population pharmacokinetics in healthy women or women with endometriosis or uterine fibroids. CONCLUSIONS: Elagolix population pharmacokinetics modeling did not reveal any patient-related factors or clinical parameters that would require dose adjustments for the approved dosage of 300 mg twice daily with estradiol 1 mg /norethindrone acetate 0.5 mg daily, in women with heavy menstrual bleeding associated with uterine fibroids. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT01620528 (EM-1), NCT01760954 (EM-1-Extend), NCT01931670 (EM-2), NCT02143713 (EM-2-Extend), NCT02654054 (UF-1), NCT02691494 (UF-2), NCT0295494 (UF-Extend).

Bridging Fixed Dose to Body Weight-based Regimen of Adalimumab in Paediatric Ulcerative Colitis Using a Pharmacometric Modelling Approach: Case Study with the Phase 3 ENVISION I Trial.

BACKGROUND AND AIMS: The Phase 3 study ENVISION I demonstrated efficacy and safety of adalimumab in paediatric patients with moderate to severe ulcerative colitis. The protocol-specified high-dose adalimumab regimen was numerically more efficacious than the standard-dose regimen. The objective of this work was to bridge a fixed-dosing regimen to the protocol-specified high-induction/high-maintenance, body weight-based dosing regimen studied in ENVISION I, using a pharmacometrics modelling and simulation approach. METHODS: A stepwise strategy was implemented, including developing an adalimumab paediatric population pharmacokinetic model; using this model to determine a fixed-dosing regimen in paediatric ulcerative colitis patients which achieves similar concentrations to those observed in ENVISION I patients; determining adalimumab exposure-response relationship using population pharmacokinetic/pharmacodynamic model and data from ENVISION I; simulating clinical remission rate in paediatric ulcerative colitis patients using the Markov exposure-response model and the dosing regimen determined to provide similar efficacy to that observed in ENVISION I. RESULTS: Both developed population pharmacokinetic and pharmacokinetic/pharmacodynamic models adequately described the observed data. Adalimumab exposure was identified as a significant predictor of clinical remission at Week 8 based on logistic regression [p <0.01]. Simulated efficacy suggested that the fixed-dosing regimen performs similarly to the more efficacious dosing regimen used in ENVISION I, by providing comparable clinical remission per Partial Mayo Score response rates over time. No relationship between adalimumab exposure and adverse events was identified. CONCLUSIONS: The population pharmacokinetic/pharmacodynamic model supports the appropriateness of the use of the fixed-dosing regimen in the paediatric ulcerative colitis population.

Drug-Drug Interaction Studies of Elagolix with Oral and Transdermal Low-Dose Hormonal Add-Back Therapy.

BACKGROUND AND OBJECTIVE: Elagolix is an oral, non-peptide, gonadotropin-releasing hormone receptor antagonist. It is approved for the treatment of moderate-to-severe pain associated with endometriosis and is being investigated for the treatment of heavy menstrual bleeding associated with uterine fibroids. Use of low-dose hormonal add-back therapy can reduce hypoestrogenic effects associated with elagolix, thus there is a need to determine if there is a pharmacokinetic interaction between elagolix and low-dose hormonal add-back therapy. METHODS: Two multiple-dose, open-label, single-sequence, non-randomized studies for elagolix 300 mg twice daily with oral (n = 24) and transdermal (n = 36) low-dose add-back therapy (estradiol [E2]/norethindrone acetate [NETA]; 1 mg/0.5 mg oral and 0.51 mg/4.8 mg transdermal) in healthy postmenopausal women were conducted, with pharmacokinetic sampling for E2, estrone (E1), and NETA up to 72 or 96 h after dosing. Pharmacokinetic parameters for hormones were estimated using noncompartmental methods. RESULTS: No change in norethindrone maximum plasma concentration or area under the concentration-time curve was observed when oral E2/NETA was administered with elagolix. For E2, there was a 2-fold increase in maximum plasma concentration and a 1.5-fold increase in the area under the concentration-time curve, and for E1 there was a 1.7-fold increase in maximum plasma concentration when oral E2/NETA was administered with elagolix. Exposures for norethindrone, E2, and E1 were unchanged when transdermal E2/NETA was applied with elagolix administration. CONCLUSIONS: Although changes in E2/E1 exposures were observed when oral E2/NETA was co-administered with elagolix, these changes are not considered clinically relevant; and no dose adjustments are recommended when elagolix is co-administered with oral or transdermal low-dose add-back therapy.

Comparative Bioavailability of Two Formulations of Biopharmaceutical Classification System (BCS) Class IV Drugs: A Case Study of Lopinavir/Ritonavir.

BACKGROUND: Lopinavir/ritonavir (LPV/r-A, Kaletra®), a fixed dose, co-formulated antiviral therapy for the treatment of HIV infection has been used worldwide for over two decades. Both active substances have low solubility in water and low membrane permeability. LPV/r-A tablets contain key excipients critical to ensuring acceptable bioavailability of lopinavir and ritonavir in humans. An established dog pharmacokinetic model demonstrated several generic LPV/r tablet formulations have significant oral bioavailability variability compared to LPV/r-A. METHODS: Analytical characterizations of LPV/r-B tablets were performed and a clinical study was conducted to assess the relative bioavailability of Kalidavir® (LPV/r-B) 400/100 mg tablets relative to Kaletra® (LPV/r-A) 400/100 mg tablets under fasting conditions. RESULTS: The presence of active substances were confirmed in LPV/r-B tablets in an apparent amorphous state at essentially the labeled amounts, and dissolution profiles were generally similar to LPV/r-A tablets. Excipients in the tablet formulation were found to be variable and deviate from the labeled composition. Lopinavir and ritonavir exposures (AUC) following LPV/r-B administration were approximately 90% and 20% lower compared to that of LPV/r-A. CONCLUSIONS: LPV/r-B was not shown to be bioequivalent to LPV/r-A.

Validation of a quantitative systems pharmacology model of calcium homeostasis using elagolix Phase 3 clinical trial data in women with endometriosis.

Elagolix is a novel, oral gonadotropin-releasing hormone receptor antagonist indicated for the management of moderate to severe pain associated with endometriosis and heavy menstrual bleeding associated with uterine fibroids. Consistent with its mechanism of action, elagolix exhibited dose-dependent suppression of estradiol (E2) in clinical studies. A dose-response model that describes the relationship between elagolix dosages and average E2 levels was combined with a previously published quantitative systems pharmacology (QSP) model of calcium homeostasis to predict bone mineral density (BMD) changes during and following elagolix treatment. In the QSP model, changes in E2 levels were linked to downstream changes in markers of bone resorption (carboxyterminal cross-linked telopeptide of type 1 collagen [CTX]), formation (N-terminal propeptide of type 1 procollagen [P1NP]) and BMD. The BMD, CTX, and P1NP predictions by the QSP model were validated against observed data from four phase III clinical trials of elagolix in premenopausal women with endometriosis. BMD, CTX, and P1NP were successfully described by the QSP model, without any model fitting, suggesting that the model was validated for further predictions of elagolix effects on BMD. Simulations using the validated QSP model demonstrated that elagolix 150 mg once daily dosing for 24 months is predicted to result in -0.91% change from baseline in lumbar spine BMD. The QSP model simulation results were part of the totality of evidence to support the approved duration of therapy for elagolix 150 mg once daily in patients with endometriosis.