Efficacy and safety of ombitasvir/paritaprevir/ritonavir and dasabuvir with low-dose ribavirin in patients with chronic hepatitis C virus genotype 1a infection without cirrhosis.

Patients infected with hepatitis C virus (HCV) treated with interferon-free direct-acting antivirals may still require ribavirin. However, ribavirin is associated with adverse events that can limit its use. This open-label, multicentre, Phase 3 study evaluated the safety and efficacy of ombitasvir/paritaprevir/ritonavir + dasabuvir (OBV/PTV/r + DSV) with low-dose ribavirin for 12 weeks in genotype 1a-infected patients without cirrhosis. The primary efficacy endpoint was sustained virologic response at post-treatment Week 12 (SVR12). The primary safety endpoint was haemoglobin <10 g/dL during treatment and decreased from baseline. Overall, 105 patients enrolled. The SVR12 rate was 89.5% (n/N = 94/105; 95% CI, 83.7-95.4). The study did not achieve noninferiority versus the historic SVR12 rate for OBV/PTV/r + DSV plus weight-based ribavirin. Five patients experienced virologic failure, four discontinued, and two had missing SVR12 data. Excluding nonvirologic failures, the SVR12 rate was 94.9% (n/N = 94/99). One patient met the primary safety endpoint. OBV/PTV/r + DSV plus low-dose ribavirin offers an alternative option for patients in whom full-dose ribavirin may compromise tolerability, although noninferiority to the weight-based ribavirin regimen was not met.

Lamotrigine pharmacokinetics following oral and stable-labeled intravenous administration in young and elderly adult epilepsy patients: Effect of age.

OBJECTIVE: The objectives of this study were to investigate the effect of age on pharmacokinetic parameters of lamotrigine (LTG) and estimate parameter variability. METHODS: Patients (>18 years old) who were already on a steady-state dose of LTG therapy with no interacting comedications were enrolled. Patients with significant cardiac disease, severe kidney dysfunction, or moderate-to-severe liver dysfunction were excluded. Fifty milligrams of a stable-labeled intravenous LTG formulation (SL-LTG) replaced 50 mg of a patient's normal daily oral LTG dose. Thirteen blood samples were collected in each person over 96 hours. SL-LTG and unlabeled LTG concentrations were measured simultaneously by gas chromatography-mass spectrometry. Concentration-time data were analyzed by nonlinear mixed-effects modeling (NONMEM version 7.3). RESULTS: Twenty-eight patients representing 16 young (18-48 years old) and 12 elderly (63-87 years old) patients were included, yielding 382 unlabeled and 351 SL-LTG concentrations. A two-compartment model with first-order absorption and elimination adequately described the plasma concentration-time data. Bioavailability of oral LTG was approximately 74% and did not differ by age. LTG clearance was 27.2% lower in elderly than in young patients (1.80 L/h for a 70-kg patient). SIGNIFICANCE: Although LTG bioavailability was not affected by age, LTG clearance was 27.2% lower in elderly versus young patients of comparable body weight, possibly indicating lower dosages being needed in this population.

Population pharmacokinetics of paritaprevir, ombitasvir, dasabuvir, ritonavir and ribavirin in hepatitis C virus genotype 1 infection: analysis of six phase III trials.

AIM: The aim of the current study was to characterize the population pharmacokinetics of a triple direct-acting antiviral (DAA) regimen (3D) (ombitasvir, paritaprevir-ritonavir and dasabuvir) and adjunctive ribavirin, and estimate covariate effects in a broad spectrum of subjects with hepatitis C virus (HCV) genotype 1 infection. METHODS: Pharmacokinetic data from six phase III studies and one phase II study in subjects receiving the currently approved doses of the 3D ± ribavirin regimen for treating HCV genotype 1 infection for 12 weeks or 24 weeks were characterized using separate population pharmacokinetic models, built using each component of the regimen from nonlinear mixed-effects methodology in NONMEM 7.3. In the models, demographic and clinical covariates were tested. Models were assessed via goodness-of-fit plots, visual predictive checks and bootstrap evaluations. RESULTS: The population pharmacokinetic models for each component of the 3D ± ribavirin regimen (DAAs and ritonavir, n = 2348) and ribavirin (n = 1841) adequately described their respective plasma concentration-time data. Model parameter estimates were precise and robust, and all models showed good predictive ability. Significant covariate effects associated with apparent clearance and volume of distribution included age, body weight, gender, cirrhosis, HCV subtype, opioid or antidiabetic agent use, and creatinine clearance. CONCLUSION: The population pharmacokinetics of the 3D ± ribavirin regimen components in HCV-infected patients were characterized using phase II and III HCV clinical trial data. Although several statistically significant covariates were identified, their effects were modest and not clinically meaningful to necessitate dose adjustments for any component of the 3D regimen.

Sustained virologic response of 100% in HCV genotype 1b patients with cirrhosis receiving ombitasvir/paritaprevir/r and dasabuvir for 12weeks.

BACKGROUND & AIMS: Patients with chronic hepatitis C virus (HCV) infection and cirrhosis have a higher risk for liver-related complications and have historically been more difficult to cure than patients without cirrhosis. We evaluated the safety and efficacy of ombitasvir/paritaprevir/ritonavir and dasabuvir, without ribavirin, for 12weeks in patients with HCV genotype 1b infection and compensated cirrhosis. METHODS: Treatment-naïve and peginterferon/ribavirin treatment-experienced patients received 12weeks of ombitasvir/paritaprevir/ritonavir (25/150/100mg once daily) and dasabuvir (250mgtwicedaily). Key inclusion criteria were hemoglobin ⩾10g/dl, albumin ⩾2.8g/dl, platelet count ⩾25×10(9)/L, creatinine clearance ⩾30ml/min, and Child-Pugh score ⩽6. Efficacy was assessed by the percentage of patients achieving SVR (HCV RNA <25IU/ml) 12weeks post-treatment (SVR12). Efficacy and safety were assessed in all patients receiving study drug. RESULTS: Sixty patients with HCV genotype 1b infection and cirrhosis received treatment. The study population comprised 62% male, 55% treatment-experienced, 83% with IL28B non-CC genotype, 22% with platelet count <90×10(9)/L, and 17% with albumin <3.5g/dl. All 60 patients completed treatment, and SVR12 was achieved in 100% (95% CI, 94.0-100%) of patients. The most common adverse events were fatigue (22%), diarrhea (20%), and headache (18%). Only one patient (1.7%) experienced a serious adverse event. Laboratory abnormalities were infrequently observed and not clinically significant. CONCLUSIONS: The HCV regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir without ribavirin for 12weeks achieved 100% SVR12 and was well tolerated in HCV genotype 1b-infected patients with cirrhosis, suggesting that this 12-week ribavirin-free regimen is sufficient in this population.

Drug Interactions with the Direct-Acting Antiviral Combination of Ombitasvir and Paritaprevir-Ritonavir.

The two direct-acting antiviral (2D) regimen of ombitasvir and paritaprevir (administered with low-dose ritonavir) is being developed for treatment of genotype subtype 1b and genotypes 2 and 4 chronic hepatitis C virus (HCV) infection. Drug-drug interactions were evaluated in healthy volunteers to develop dosing recommendations for HCV-infected subjects. Mechanism-based interactions were evaluated for ketoconazole, pravastatin, rosuvastatin, digoxin, warfarin, and omeprazole. Interactions were also evaluated for duloxetine, escitalopram, methadone, and buprenorphine-naloxone. Ratios of geometric means with 90% confidence intervals for the maximum plasma concentration and the area under the plasma concentration-time curve were estimated to assess the magnitude of the interactions. For most medications, coadministration with the 2D regimen resulted in a <50% change in exposures. Ketoconazole, digoxin, pravastatin, and rosuvastatin exposures increased by up to 105%, 58%, 76%, and 161%, respectively, and omeprazole exposures decreased by approximately 50%. Clinically meaningful changes in ombitasvir, paritaprevir, or ritonavir exposures were not observed. In summary, all 11 medications evaluated can be coadministered with the 2D regimen, with most medications requiring no dose adjustment. Ketoconazole, digoxin, pravastatin, and rosuvastatin require lower doses, and omeprazole may require a higher dose. No dose adjustment is required for the 2D regimen.

Ombitasvir/paritaprevir/r and dasabuvir plus ribavirin in HCV genotype 1-infected patients on methadone or buprenorphine.

BACKGROUND & AIMS: Hepatitis C virus (HCV)-infected patients with a history of injection drug use have low rates of initiation and completion of interferon-based therapies. This study evaluated efficacy, safety, and pharmacokinetics of a 12-week all-oral regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir+ribavirin in HCV genotype 1-infected patients on stable opioid replacement therapy. METHODS: This was a phase II, multicenter, open-label, single-arm study in treatment-naïve or peginterferon/ribavirin treatment-experienced HCV genotype 1-infected patients on methadone or buprenorphine±naloxone. Patients received 12weeks of co-formulated ombitasvir/paritaprevir/ritonavir (25mg/150mg/100mg once daily) and dasabuvir (250mg twice daily)+weight-based ribavirin. The primary efficacy endpoint was sustained virologic response 12 weeks post-treatment. RESULTS: Thirty-eight non-cirrhotic patients on chronic methadone (n=19) or buprenorphine (n=19) were enrolled. A total of 37 patients (97.4%) had a sustained virologic response 12 weeks post-treatment. No patient had a viral breakthrough or relapse. One patient discontinued due to serious adverse events unrelated to study drug (cerebrovascular accident and sarcoma). The most frequent adverse events were nausea, fatigue, and headache. Eight patients had on-treatment hemoglobin concentrations <10g/dl. Pharmacokinetic analyses indicated no clinically meaningful impact of methadone or buprenorphine on ombitasvir, paritaprevir, ritonavir, dasabuvir, or dasabuvir M1 metabolite exposures. No dose adjustments of methadone or buprenorphine were required. CONCLUSIONS: The interferon-free regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir+ribavirin for 12weeks was well tolerated and achieved sustained virologic response in 97.4% of patients on opioid substitution therapy in this study. This all-oral regimen may provide an effective alternative to interferon-based therapies for HCV-infected patients with a history of injection drug use.

Drug-drug interaction profile of the all-oral anti-hepatitis C virus regimen of paritaprevir/ritonavir, ombitasvir, and dasabuvir.

BACKGROUND & AIMS: Paritaprevir (administered with ritonavir, PTV/r), ombitasvir (OBV), and dasabuvir (DSV) are direct-acting antiviral agents (DAAs) for the treatment of chronic hepatitis C virus (HCV) infection. Thirteen studies were conducted to characterize drug-drug interactions for the 3D regimen of OBV, PTV/r, and DSV and various medications in healthy volunteers to inform dosing recommendations in HCV-infected patients. METHODS: Mechanism-based drug-drug interactions were evaluated for gemfibrozil, ketoconazole, carbamazepine, warfarin, omeprazole, digoxin, pravastatin, and rosuvastatin. Drug-drug interactions with medications commonly used in HCV-infected patients were evaluated for amlodipine, furosemide, alprazolam, zolpidem, duloxetine, escitalopram, methadone, buprenorphine/naloxone, and oral contraceptives. Ratios of geometric means with 90% confidence intervals for maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) were used to determine the magnitude of interaction. RESULTS: Coadministration with the 3D regimen of OBV, PTV/r, and DSV resulted in a <2-fold change in mean Cmax and AUC for most medications and the DAAs, indicating minimal to modest interactions. Carbamazepine decreased PTV, ritonavir, and DSV exposures substantially, while gemfibrozil increased DSV exposures substantially. Although coadministration with ethinyl estradiol-containing contraceptives resulted in elevated alanine aminotransferase levels, coadministration with a progestin-only contraceptive did not. CONCLUSIONS: The majority of medications can be coadministered with the 3D regimen of OBV, PTV/r, and DSV without dose adjustment, or with clinical monitoring or dose adjustment. Although no dose adjustment is necessary for the 3D regimen when coadministered with 17 of the 20 medications, coadministration with gemfibrozil, carbamazepine, or ethinyl estradiol-containing contraceptives is contraindicated.

Pharmacokinetics and immunogenicity of eftozanermin alfa in subjects with previously-treated solid tumors or hematologic malignancies: results from a phase 1 first-in-human study.

PURPOSE: Eftozanermin alfa is a second-generation tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor agonist that enhances death receptor 4/5 clustering on tumor cells to induce apoptosis. We report the pharmacokinetics and immunogenicity of eftozanermin alfa administered intravenously to 153 adults with previously-treated solid tumors or hematologic malignancies from the first-in-human, open-label, dose-escalation and dose-optimization study. METHODS: Dose escalation evaluated eftozanermin alfa monotherapy 2.5-15 mg/kg on Day 1 or Days 1/8 of a 21-day cycle. Dose optimization evaluated eftozanermin alfa monotherapy or combination therapy with either oral venetoclax 400-800 mg daily (eftozanermin alfa 1.25-7.5 mg/kg Days 1/8/15 of a 21-day cycle) or chemotherapy (eftozanermin alfa 3.75 or 7.5 mg/kg Days 1/8/15/22 of a 28-day cycle and FOLFIRI regimen [leucovorin, 5-fluorouracil, and irinotecan] with/without bevacizumab on Days 1/15 of a 28-day cycle). RESULTS: Systemic exposures (maximum observed concentration [Cmax] and area under the concentration-time curve [AUC]) of eftozanermin alfa were approximately dose-proportional across the entire dose escalation range with minimal to no accumulation in Cycle 3 versus Cycle 1 exposures. Comparable exposures and harmonic mean half-lives (35.1 h [solid tumors], 31.3 h [hematologic malignancies]) were observed between malignancy types. Exposures (dose-normalized Cmax and AUC) in Japanese subjects were similar to non-Japanese subjects. Furthermore, eftozanermin alfa/venetoclax combination therapy did not have an impact on the exposures of either agent. Treatment-emergent anti-drug antibodies were observed in 9.4% (13/138) of subjects. CONCLUSIONS: The study results, including a pharmacokinetic profile consistent with weekly dosing and low incidence of immunogenicity, support further investigation of eftozanermin alfa. TRIAL REGISTRATION ID: NCT03082209.

A Phase I First-in-Human Study of ABBV-383, a B-Cell Maturation Antigen × CD3 Bispecific T-Cell Redirecting Antibody, in Patients With Relapsed/Refractory Multiple Myeloma.

PURPOSE: ABBV-383, a B-cell maturation antigen × CD3 T-cell engaging bispecific antibody, has demonstrated promising results in an ongoing first-in-human phase I study (ClinicalTrials.gov identifier: NCT03933735) in patients with relapsed/refractory multiple myeloma (RRMM). Herein, we report safety and efficacy outcomes of this phase I dose escalation/expansion study. METHODS: Patients with RRMM (≥ three prior lines including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 monoclonal antibody) were eligible. ABBV-383 was administered intravenously over 1-2 hours once every 3 weeks, without any step dosing. A 3 + 3 design with backfilling for dose escalation was used (intrapatient escalation to highest safe dose permitted) followed by initiation of dose expansion. RESULTS: As of January 8, 2022, 124 patients (dose escalation [0.025-120 mg], n = 73; dose expansion [60 mg], n = 51) have received ABBV-383; median age was 68 years (range, 35-92 years). The most common hematologic treatment-emergent adverse events (TEAEs) were neutropenia (all grades: 37%) and anemia (29%). The most common nonhematologic TEAEs were cytokine release syndrome (57%) and fatigue (30%). Seven deaths from TEAEs were reported with all considered unrelated to study drug by the investigator. For all efficacy-evaluable patients (n = 122; all doses), the objective response rate (ORR) was 57% and very good partial response (VGPR) or better (≥ VGPR) rate was 43%. In the 60 mg dose expansion cohort (n = 49), the ORR and ≥ VGPR rates were 59% and 39%, respectively; and in the ≥ 40 mg dose escalation plus dose expansion cohorts (n = 79) were 68% and 54%, respectively. CONCLUSION: ABBV-383 in patients with RRMM was well tolerated with an ORR of 68% at doses ≥ 40 mg. This novel therapy's promising preliminary antitumor activity in heavily pretreated patients warrants further clinical evaluation.

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.

First-in-Human Phase I Study of ABBV-085, an Antibody-Drug Conjugate Targeting LRRC15, in Sarcomas and Other Advanced Solid Tumors.

PURPOSE: Leucine-rich repeat containing 15 (LRRC15) is expressed on stromal fibroblasts in the tumor microenvironment of multiple solid tumor types and may represent an interesting target for therapy, particularly in patients with sarcomas where LRRC15 is also expressed by malignant cells. ABBV-085 is a monomethyl auristatin-E antibody-drug conjugate that targets LRRC15 and showed antineoplastic efficacy in preclinical experiments. Herein, we report findings of ABBV-085 monotherapy or combination therapy in adult patients with sarcomas and other advanced solid tumors. PATIENTS AND METHODS: This first-in-human phase I study (NCT02565758) assessed ABBV-085 safety, pharmacokinetics/pharmacodynamics, and preliminary antitumor activity. The study consisted of two parts: dose escalation and dose expansion. ABBV-085 was administered by intravenous infusion at 0.3 to 6.0 mg/kg every 14 days. RESULTS: In total, 85 patients were enrolled; 45 patients received the recommended expansion dose of 3.6 mg/kg ABBV-085 monotherapy, including 10 with osteosarcoma and 10 with undifferentiated pleomorphic sarcoma (UPS). Most common treatment-related adverse events were fatigue, nausea, and decreased appetite. The overall response rate for patients with osteosarcoma/UPS treated at 3.6 mg/kg was 20%, including four confirmed partial responses. No monotherapy responses were observed for other advanced cancers treated at 3.6 mg/kg. One patient treated with ABBV-085 plus gemcitabine achieved partial response. CONCLUSIONS: ABBV-085 appeared safe and tolerable at a dose of 3.6 mg/kg every 14 days, with preliminary antitumor activity noted in patients with osteosarcoma and UPS. Given the high unmet need in these orphan malignancies, further investigation into targeting LRRC15 in these sarcomas may be warranted.

Effect of Elagolix Exposure on Clinical Efficacy End Points in Phase III Trials in Women With Endometriosis-Associated Pain: An Application of Markov Model.

Elagolix is an oral gonadotropin-releasing hormone antagonist approved by the US Food and Drug Administration (FDA) for the management of moderate-to-severe pain associated with endometriosis and in combination with estradiol/norethindrone acetate approved for the management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women. The objective of this work was to characterize the relationships between elagolix exposures and clinical efficacy response rates for dysmenorrhea (DYS) and nonmenstrual pelvic pain (NMPP) in premenopausal women enrolled in the pivotal phase III studies with moderate-to-severe pain associated with endometriosis. Relationships between elagolix average concentrations (Cavg ) and efficacy responses (DYS and NMPP) were characterized using a nonlinear mixed-effects discrete-time first order Markov modeling approach. Only age was statistically significant for NMPP but not considered clinically relevant. This work indicates that the selection of elagolix dose is not determined based on tested patient demographics, baseline, or endometriosis disease severity measures in covariate analysis. In other words, the work suggests no preference of one regimen over the other to treat endometriosis-associated pain (DYS or NMPP) for any patient subpopulation based on tested covariate groups.

Exposure-Response Relationships for Efficacy and Safety of Risankizumab in Phase II and III Trials in Psoriasis Patients.

Risankizumab has demonstrated efficacy in phase III trials in patients with moderate-to-severe plaque psoriasis. The exposure-response relationships for risankizumab efficacy (Psoriasis Area and Severity Index (PASI)75, PASI90, PASI100, and static Physician's Global Assessment (sPGA)0/1) at week 16 (N = 1,732) and week 52 (N = 598) as well as safety (incidence of any adverse event, serious adverse event, infection and infestation, or serious infection) over up to 52 weeks were characterized using the data from risankizumab phase II and III clinical trials in patients with moderate-to-severe plaque psoriasis. Impact of clinically relevant covariates was evaluated. Risankizumab phase III regimen (150 mg subcutaneously at weeks 0, 4, and every 12 weeks thereafter) achieved the plateau of the exposure-efficacy relationships with model-estimated PASI90 and sPGA0/1 response probabilities of 77%, and 87%, respectively, at week 16 and 85%, and 88%, respectively, at week 52. There was no apparent relationship between risankizumab plasma exposure and the evaluated safety variables.

Exposure-Safety Analyses Identify Predictors of Change in Bone Mineral Density and Support Elagolix Labeling for Endometriosis-Associated Pain.

Elagolix is a novel oral gonadotropin releasing hormone receptor antagonist, that can suppress estradiol in a dose-dependent manner. It is indicated for management of moderate-to-severe pain associated with endometriosis. A population exposure-response model describing the relationship between elagolix exposure and changes in bone mineral density (BMD) was developed using data from four phase III studies in premenopausal women with endometriosis-associated pain. Elagolix pharmacokinetic exposure-dependent changes in BMD were described by an indirect-response maximum effect (Emax ) model through stimulation of bone resorption. African American race, higher body mass index (BMI), and lower type-I collagen C-telopeptide concentrations were significantly associated with higher baseline BMD. Higher BMI was significantly associated with higher bone formation rates. Simulations using the final model demonstrated that elagolix 150 mg q.d. dosing for 24 months is predicted to result in -1.45% (-2.04 to -0.814) decrease from baseline in BMD and were used to support corresponding dosing recommendations in the label.

Assessment of Clinical Drug-Drug Interactions of Elagolix, a Gonadotropin-Releasing Hormone Receptor Antagonist.

Elagolix is an oral gonadotropin-releasing hormone receptor antagonist indicated for the management of endometriosis-associated pain and in combination with estradiol/norethindrone acetate indicated for the management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women. Elagolix coadministered with estradiol/norethindrone acetate is in late-stage development for the management of heavy menstrual bleeding associated with uterine fibroids. Based on the in vitro profile of elagolix metabolism and disposition, 9 drug-drug interaction (DDI) studies evaluating the victim and perpetrator characteristics of elagolix were conducted in 144 healthy volunteers. As a victim of cytochrome P450 (CYPs) and transporter-mediated DDIs, elagolix area under the curve (AUC) increased by ∼2-fold following coadministration with ketoconazole and by ∼5- and ∼2-fold with single and multiple doses of rifampin, respectively. As a perpetrator, elagolix decreased midazolam AUC (90% confidence interval) by 54% (50%-59%) and increased digoxin AUC by 32% (23%-41%). Elagolix decreased rosuvastatin AUC by 40% (29%-50%). No clinically significant changes in exposure on coadministration with sertraline or fluconazole occurred. A elagolix 150-mg once-daily regimen should be limited to 6 months with strong CYP3A inhibitors and rifampin because of the potential increase in bone mineral density loss, as described in the drug label. A 200-mg twice-daily regimen is recommended for no more than 1 month with strong CYP3A inhibitors and not recommended with rifampin. Elagolix is contraindicated with strong organic anion transporter polypeptide B1 inhibitors (eg, cyclosporine and gemfibrozil). Consider increasing the doses of midazolam and rosuvastatin when coadministered with elagolix, and individualize therapy based on patient response. Clinical monitoring is recommended for P-glycoprotein substrates with a narrow therapeutic window (eg, digoxin). Dose adjustments are not required for sertraline, fluconazole, bupropion (or any CYP2B6 substrate), or elagolix when coadministered.

Clinical Pharmacology of Elagolix: An Oral Gonadotropin-Releasing Hormone Receptor Antagonist for Endometriosis.

The clinical pharmacology of elagolix was extensively evaluated in clinical studies in healthy subjects and in women with endometriosis. Elagolix pharmacokinetics (PK) show significant population variability, however they are minimally affected by patients' baseline characteristics and demographics, except for clinically relevant extrinsic and intrinsic factors such as coadministrated strong organic anion transporting polypeptide (OATP) 1B1 inhibitors and severe hepatic impairment, which are contraindications for the use of elagolix. These studies enabled a comprehensive understanding of elagolix mechanism of action and the downstream pharmacodynamic (PD) effects on gonadotropin and ovarian hormones, as well as full characterization of the PK/PD (PKPD) relationships of elagolix at various dosages, including the approved 150 mg once daily and 200 mg twice daily dosing regimens for the management of moderate to severe pain associated with endometriosis. Several model-based analyses have contributed to understanding of the benefit-risk profile of elagolix in patients with endometriosis, through characterization of the exposure relationship with responder rates, with changes in bone mineral density over time, as well as the interaction with coadministered drugs. Collectively, these studies and analyses served as supportive evidence for the effectiveness of the approved dosages and provided general dosing instructions of the first approved oral gonadotropin-releasing hormone receptor antagonist.

Population Pharmacokinetics of Elagolix in Healthy Women and Women with Endometriosis.

INTRODUCTION: Elagolix is a novel, orally active, non-peptide, competitive gonadotropin-releasing hormone (GnRH) receptor antagonist in development for the management of endometriosis with associated pain and heavy menstrual bleeding due to uterine fibroids. The pharmacokinetics of elagolix have been well-characterized in phase I studies; however, elagolix population pharmacokinetics have not been previously reported. Therefore, a robust model was developed to describe elagolix population pharmacokinetics and to evaluate factors affecting elagolix pharmacokinetic parameters. METHODS: The data from nine clinical studies (a total of 1624 women) were included in the analysis: five phase I studies in healthy, premenopausal women and four phase III studies in premenopausal women with endometriosis. RESULTS: Elagolix population pharmacokinetics were best described by a two-compartment model with a lag time in absorption. Of the 15 covariates tested for effect on elagolix apparent clearance (CL/F) and/or volume of distribution only one covariate, organic anion transporting polypeptide (OATP) 1B1 genotype status, had a statistically significant, but not clinically meaningful, effect on elagolix CL/F. CONCLUSION: Elagolix pharmacokinetics were not affected by patient demographics and were similar between healthy women and women with endometriosis. Clinical Trial Registration Numbers NCT01403038, NCT01620528, NCT01760954, NCT01931670, NCT02143713.

Clinical Pharmacokinetics of Paritaprevir.

Paritaprevir is a potent hepatitis C virus (HCV) nonstructural (NS) protein 3/4A protease inhibitor that is used in combination with other direct-acting antivirals (DAAs) for the treatment of chronic HCV infection. Paritaprevir is primarily metabolized by cytochrome P450 (CYP) 3A4 and is administered with a low dose of ritonavir to achieve drug concentrations suitable for once-daily dosing. Coadministration of paritaprevir with ritonavir increases the half-life of single-dose paritaprevir from approximately 3 h to 5-8 h, doubles the time to maximum plasma concentration (T max) from 2.3 to 4.7 h, and increases exposures 30-fold for maximum observed plasma concentration (C max), 50-fold for area under the plasma concentration-time curve (AUC), and >300-fold for trough concentration (C 24). Paritaprevir displays highly variable, nonlinear pharmacokinetics, with C max and AUC increasing in a greater than dose proportional manner when administered with or without ritonavir. In the presence of ritonavir, paritaprevir is excreted mostly unchanged in feces via biliary excretion. Paritaprevir exposures are higher in Japanese subjects compared with Caucasian subjects; however, no dose adjustment is needed for Japanese patients as the higher exposures are safe and well tolerated. The pharmacokinetic characteristics of paritaprevir are similar between healthy subjects and HCV-infected patients, and are not appreciably altered by mild or moderate hepatic impairment or mild, moderate, or severe renal impairment, including those on dialysis. Paritaprevir exposures are increased in patients with severe hepatic impairment. Although the presence of a low dose of ritonavir in paritaprevir-containing regimens increases the likelihood of drug-drug interactions, results from several drug interaction studies demonstrated that paritaprevir-containing regimens can be coadministered with many comedications that are commonly prescribed in HCV-infected patients.

Population Pharmacokinetics of Paritaprevir, Ombitasvir, and Ritonavir in Japanese Patients with Hepatitis C Virus Genotype 1b Infection.

BACKGROUND AND OBJECTIVE: Hepatitis C virus (HCV) infection is of considerable clinical concern in Japan. We modeled the population pharmacokinetics of an oral interferon-free, direct-acting antiviral agent (DAA) regimen (i.e., the 2D regimen) recently approved for the treatment of chronic HCV genotype 1 infection as a new option for affected Japanese patients. METHODS: Using data from a phase III clinical trial (GIFT-I) that enrolled Japanese patients with HCV genotype 1b infection, population pharmacokinetic models were developed for the drugs that comprise the 2D regimen: paritaprevir, ombitasvir, and ritonavir. Demographic and clinical covariates with potential to influence 2D pharmacokinetics were evaluated for their effects on drug exposures. Proposed models were assessed using goodness-of-fit plots, visual predictive checks, and bootstrap evaluations. RESULTS: One-compartment models with first-order absorption and elimination adequately described the population pharmacokinetics of paritaprevir, ombitasvir, and ritonavir. On average, patients with cirrhosis had approximately 95-145 % higher, 19-24 % lower, and 58-68 % higher exposures of paritaprevir, ombitasvir, and ritonavir, respectively. Female patients had 58-81 % higher ombitasvir exposures, whereas patients with mild renal impairment (creatinine clearance 75 mL/min) had 9-14 % higher ombitasvir exposures than did patients with normal renal function (creatinine clearance 105 mL/min). The DAA exposure values were comparable between responders and non-responders. CONCLUSION: Population pharmacokinetic modeling did not reveal any patient-related or clinical parameters that would require dose adjustment of the 2D regimen when used for the treatment of HCV genotype 1b infection in Japanese patients.

Effects of Mild and Moderate Renal Impairment on Ombitasvir, Paritaprevir, Ritonavir, Dasabuvir, and Ribavirin Pharmacokinetics in Patients with Chronic HCV Infection.

BACKGROUND AND AIMS: Ombitasvir, paritaprevir (given with low-dose ritonavir), and dasabuvir are direct-acting antivirals (DAAs) used with or without ribavirin for the treatment of chronic hepatitis C virus (HCV) infection. The objective of this analysis was to evaluate the effect of renal function as determined by creatinine clearance (CrCL) on the pharmacokinetics of the DAAs, ritonavir, and ribavirin in HCV genotype 1-infected patients with or without cirrhosis. METHODS: Total exposure, measured by area under the plasma concentration-time curve (AUC), was generated for the DAAs, ritonavir, and ribavirin using population pharmacokinetic modeling of data (N = 2093 patients) from 6 Phase 3 studies and 1 Phase 2 study. The effect of CrCL on the AUC values of each DAA, ritonavir, and ribavirin was separately evaluated and adjusted for any significant patient-specific covariates including, age, sex, body weight, cirrhosis, and Asian race in multiple linear regression analysis. Using the final models, AUC values were predicted for patients with normal renal function (CrCL = 105 mL/min), mild renal impairment (CrCL = 75 mL/min) and moderate renal impairment (CrCL = 45 mL/min). RESULTS: CrCL was not a statistically significant predictor of DAA or ritonavir AUC values. Age, sex, and cirrhosis were significant covariates for the AUC values of all the DAAs and body weight was a significant covariate for the AUC values of ombitasvir and dasabuvir. Asian race was significant only for dasabuvir. Only age and sex were statistically significant predictors for the AUC values of ritonavir. CrCL showed a significant relationship with the ribavirin AUC values, consistent with ribavirin's renal excretion. Age, sex, body weight, and cirrhosis were also significant covariates for the AUC values of ribavirin. The DAA and ritonavir AUC values were comparable (≤10 % difference) among different levels of renal function, while ribavirin AUC values were up to 17 % higher in mild/moderate renal impairment compared with normal renal function. CONCLUSIONS: No dose adjustments are needed for the 3D regimen in HCV genotype-1 infected patients with mild or moderate renal impairment. Ribavirin doses should be adjusted for renal impairment as recommended in the ribavirin label.