A Phase I Study of Acapatamab, a Half-life Extended, PSMA-Targeting Bispecific T-cell Engager for Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: Safety and efficacy of acapatamab, a prostate-specific membrane antigen (PSMA) x CD3 bispecific T-cell engager were evaluated in a first-in-human study in metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: Patients with mCRPC refractory to androgen receptor pathway inhibitor therapy and taxane-based chemotherapy received target acapatamab doses ranging from 0.003 to 0.9 mg in dose exploration (seven dose levels) and 0.3 mg (recommended phase II dose) in dose expansion intravenously every 2 weeks. Safety (primary objective), pharmacokinetics, and antitumor activity (secondary objectives) were assessed. RESULTS: In all, 133 patients (dose exploration, n = 77; dose expansion, n = 56) received acapatamab. Cytokine release syndrome (CRS) was the most common treatment-emergent adverse event seen in 97.4% and 98.2% of patients in dose exploration and dose expansion, respectively; grade ≥ 3 was seen in 23.4% and 16.1%, respectively. Most CRS events were seen in treatment cycle 1; incidence and severity decreased at/beyond cycle 2. In dose expansion, confirmed prostate-specific antigen (PSA) responses (PSA50) were seen in 30.4% of patients and radiographic partial responses in 7.4% (Response Evaluation Criteria in Solid Tumors 1.1). Median PSA progression-free survival (PFS) was 3.3 months [95% confidence interval (CI): 3.0-4.9], radiographic PFS per Prostate Cancer Clinical Trials Working Group 3 was 3.7 months (95% CI: 2.0-5.4). Acapatamab induced T-cell activation and increased cytokine production several-fold within 24 hours of initiation. Treatment-emergent antidrug antibodies were detected in 55% and impacted serum exposures in 36% of patients in dose expansion. CONCLUSIONS: Acapatamab was safe and tolerated and had a manageable CRS profile. Preliminary signs of efficacy with limited durable antitumor activity were observed. Acapatamab demonstrated pharmacokinetic and pharmacodynamic activity.

Tarlatamab for Patients with Previously Treated Small-Cell Lung Cancer.

BACKGROUND: Tarlatamab, a bispecific T-cell engager immunotherapy targeting delta-like ligand 3 and CD3, showed promising antitumor activity in a phase 1 trial in patients with previously treated small-cell lung cancer. METHODS: In this phase 2 trial, we evaluated the antitumor activity and safety of tarlatamab, administered intravenously every 2 weeks at a dose of 10 mg or 100 mg, in patients with previously treated small-cell lung cancer. The primary end point was objective response (complete or partial response), as assessed by blinded independent central review according to the Response Evaluation Criteria in Solid Tumors, version 1.1. RESULTS: Overall, 220 patients received tarlatamab; patients had previously received a median of two lines of treatment. Among patients evaluated for antitumor activity and survival, the median follow-up was 10.6 months in the 10-mg group and 10.3 months in the 100-mg group. An objective response occurred in 40% (97.5% confidence interval [CI], 29 to 52) of the patients in the 10-mg group and in 32% (97.5% CI, 21 to 44) of those in the 100-mg group. Among patients with an objective response, the duration of response was at least 6 months in 59% (40 of 68 patients). Objective responses at the time of data cutoff were ongoing in 22 of 40 patients (55%) in the 10-mg group and in 16 of 28 patients (57%) in the 100-mg group. The median progression-free survival was 4.9 months (95% CI, 2.9 to 6.7) in the 10-mg group and 3.9 months (95% CI, 2.6 to 4.4) in the 100-mg group; the estimates of overall survival at 9 months were 68% and 66% of patients, respectively. The most common adverse events were cytokine-release syndrome (in 51% of the patients in the 10-mg group and in 61% of those in the 100-mg group), decreased appetite (in 29% and 44%, respectively), and pyrexia (in 35% and 33%). Cytokine-release syndrome occurred primarily during treatment cycle 1, and events in most of the patients were grade 1 or 2 in severity. Grade 3 cytokine-release syndrome occurred less frequently in the 10-mg group (in 1% of the patients) than in the 100-mg group (in 6%). A low percentage of patients (3%) discontinued tarlatamab because of treatment-related adverse events. CONCLUSIONS: Tarlatamab, administered as a 10-mg dose every 2 weeks, showed antitumor activity with durable objective responses and promising survival outcomes in patients with previously treated small-cell lung cancer. No new safety signals were identified. (Funded by Amgen; DeLLphi-301 ClinicalTrials.gov number, NCT05060016.).

Tarlatamab, a First-in-Class DLL3-Targeted Bispecific T-Cell Engager, in Recurrent Small-Cell Lung Cancer: An Open-Label, Phase I Study.

PURPOSE: Small-cell lung cancer (SCLC) is an aggressive malignancy with limited treatments. Delta-like ligand 3 (DLL3) is aberrantly expressed in most SCLC. Tarlatamab (AMG 757), a bispecific T-cell engager molecule, binds both DLL3 and CD3 leading to T-cellb-mediated tumor lysis. Herein, we report phase I results of tarlatamab in patients with SCLC. PATIENTS AND METHODS: This study evaluated tarlatamab in patients with relapsed/refractory SCLC. The primary end point was safety. Secondary end points included antitumor activity by modified RECIST 1.1, overall survival, and pharmacokinetics. RESULTS: By July 19, 2022, 107 patients received tarlatamab in dose exploration (0.003 to 100 mg; n = 73) and expansion (100 mg; n = 34) cohorts. Median prior lines of anticancer therapy were 2 (range, 1-6); 49.5% received antiprogrammed death-1/programmed death ligand-1 therapy. Any-grade treatment-related adverse events occurred in 97 patients (90.7%) and grade b % 3 in 33 patients (30.8%). One patient (1%) had grade 5 pneumonitis. Cytokine release syndrome was the most common treatment-related adverse event, occurring in 56 patients (52%) including grade 3 in one patient (1%). Maximum tolerated dose was not reached. Objective response rate was 23.4% (95% CI, 15.7 to 32.5) including two complete and 23 partial responses. The median duration of response was 12.3 months (95% CI, 6.6 to 14.9). The disease control rate was 51.4% (95% CI, 41.5 to 61.2). The median progression-free survival and overall survival were 3.7 months (95% CI, 2.1 to 5.4) and 13.2 months (95% CI, 10.5 to not reached), respectively. Exploratory analysis suggests that selecting for increased DLL3 expression can result in increased clinical benefit. CONCLUSION: In patients with heavily pretreated SCLC, tarlatamab demonstrated manageable safety with encouraging response durability. Further evaluation of this promising molecule is ongoing.

Characterization of the Effect of Upadacitinib on the Pharmacokinetics of Bupropion, a Sensitive Cytochrome P450 2B6 Probe Substrate.

This phase 1 study characterized the effect of multiple doses of upadacitinib, an oral Janus kinase 1 selective inhibitor, on the pharmacokinetics of the cytochrome P450 (CYP) 2B6 substrate bupropion. Healthy subjects (n = 22) received a single oral dose of bupropion 150 mg alone (study period 1) and on day 12 of a 16-day regimen of upadacitinib 30 mg once daily (study period 2). Serial blood samples for measurement of bupropion and hydroxybupropion plasma concentrations were collected in each study period. The central values (90% confidence intervals) for the ratios of change were 0.87 (0.79-0.96) for bupropion maximum plasma concentration (Cmax ), 0.92 (0.87-0.98) for bupropion area under the plasma-concentration time curve from time 0 to infinity (AUCinf ), 0.78 (0.72-0.85) for hydroxybupropion Cmax , and 0.72 (0.67-0.78) for hydroxybupropion AUCinf when administered with, relative to when administered without, upadacitinib. After multiple-dose administration of upadacitinib 30 mg once daily, upadacitinib mean ± SD AUC0-24 was 641 ± 177 ng·h/mL, and Cmax was 83.3 ± 30.7 ng/mL. These results confirm that upadacitinib has no relevant effect on pharmacokinetics of substrates metabolized by CYP2B6.

Exposure-Response Analyses of the Effects of Venetoclax, a Selective BCL-2 Inhibitor, on B-Lymphocyte and Total Lymphocyte Counts in Women with Systemic Lupus Erythematosus.

BACKGROUND: Venetoclax is a selective inhibitor of B-cell lymphoma-2, which plays a role in the development of various autoimmune diseases including systemic lupus erythematosus. The aim of these analyses was to quantify the exposure-response relationship for venetoclax effects on B-lymphocyte and total lymphocyte counts as pharmacodynamic markers of efficacy and safety, respectively, in women with systemic lupus erythematosus. The developed modeling framework was also used to evaluate venetoclax effects following cyclic, continuous, or induction/maintenance dosing paradigms as potential dosing alternatives in systemic lupus erythematosus. METHODS: Serial pharmacokinetic and lymphocyte count data from 73 women enrolled in a phase I study of venetoclax (single doses of 10-500 mg or two cycles of 30-600 mg or placebo once daily for 7 days followed by a 21-day washout) were analyzed using a sequential population pharmacokinetic/pharmacodynamic modeling approach. Simulations to evaluate changes in B-lymphocyte and total lymphocyte counts following different venetoclax dosing scenarios were conducted. RESULTS: Effect of venetoclax plasma exposures on B lymphocytes was described using an indirect linear response model and on total lymphocytes using a maximal response (Emax) with an effect site compartment. Baseline lymphocyte counts were significant covariates on the slope and half maximal inhibitory concentration parameter estimates for the respective models; with higher baseline counts associated with a greater reduction upon treatment with venetoclax. Model simulations showed that continuous dosing with lower doses of venetoclax (e.g., 150 mg daily) are predicted to achieve similar maximal effects on B-lymphocyte counts compared to cyclic dosing with higher doses (e.g., 400 mg 1 week on/3 weeks off); with better recovery of total lymphocyte counts during off-treatment weeks for the cyclic regimens. CONCLUSIONS: Venetoclax treatment in women with systemic lupus erythematosus was associated with exposure-dependent reductions in B lymphocytes, and to a lesser extent, total lymphocyte counts. Results from this study support evaluation of B-cell lymphoma-2 inhibitors as potential therapies for the treatment of systemic lupus erythematosus. CLINICALTRIALS.GOV: NCT01686555.

Population Pharmacokinetics of Risankizumab in Healthy Volunteers and Subjects with Moderate to Severe Plaque Psoriasis: Integrated Analyses of Phase I-III Clinical Trials.

BACKGROUND AND OBJECTIVE: Risankizumab is an anti-interleukin (IL)-23 monoclonal antibody being developed for treatment of moderate to severe plaque psoriasis. This study provided a comprehensive analysis of risankizumab pharmacokinetics in healthy subjects and patients with plaque psoriasis using data across phase I-III clinical trials. METHODS: Plasma pharmacokinetic data from 1899 subjects, including 13,123 observations, who received single or multiple intravenous or subcutaneous doses of risankizumab (0.01-5 mg/kg intravenous [IV], 200-1200 mg IV, 0.25-1 mg/kg subcutaneous [SC], and 18-300 mg SC) across the phase I-III clinical program were analyzed using a non-linear mixed-effects modeling approach. The developed model was qualified and the clinical relevance of covariates statistically correlated with risankizumab clearance (CL) was evaluated using simulation analyses. RESULTS: Risankizumab pharmacokinetics were best described using a two-compartment model with first-order absorption and elimination. Risankizumab CL, volume of distribution at steady state (Vss), and terminal-phase elimination half-life (t½) were estimated to be approximately 0.31 L/day, 11.2 L, and 28 days, respectively, for a typical 90 kg psoriatic subject, approaching steady-state plasma exposures by week 16 of dosing. Absolute SC bioavailability (F) was 89%. Bodyweight, anti-drug antibody (ADA) titers ≥ 128 (detected in only 1% of ADA-evaluable subjects in phase III studies), baseline serum albumin, high-sensitivity C-reactive protein (hs-CRP), and serum creatinine were statistically correlated with risankizumab CL; however, they had no clinically relevant impact on exposure. CONCLUSION: Risankizumab is characterized by dose-proportional, bi-exponential disposition with no difference in exposure between healthy subjects and patients with psoriasis. None of the covariates identified as being statistically correlated with risankizumab CL has a clinically meaningful impact on its exposure with the proposed psoriasis clinical regimen of 150 mg administered SC at weeks 0 and 4, and every 12 weeks thereafter. CLINICALTRIALS. GOV IDENTIFIERS: NCT01577550, NCT02054481, NCT02596217, NCT02684370, NCT02672852, NCT02684357, NCT02694523.

Models of Variability and Circadian Rhythm in Heart Rate, Blood Pressure, and QT Interval for Healthy Subjects Who Received Placebo in Phase I Trials.

This work characterized the time-course, circadian rhythm, and inherent variability in key cardiovascular variables (heart rate, corrected QT interval, and systolic and diastolic blood pressure) that are routinely collected as part of safety monitoring in phase I trials. Longitudinal data from 1,035 healthy volunteers who received placebo in 65 single-dose and multiple-dose phase I trials conducted by AbbVie were compiled and analyzed using nonlinear mixed-effects modeling. An independent nonlinear mixed-effects model was developed for each variable, and combinations of cosine functions were used to capture circadian oscillations. Gender, race, age, and body weight were significant covariates for variability in baseline measures, and the contributions of these covariates were quantitatively characterized. Based on the extensive data set analyzed, the developed models represent valuable tools to help contextualize and differentiate inherent variability that can be expected in a typical phase I setting from true drug-related cardiovascular safety signals. In addition, these placebo models can be used to support exposure-response analyses that estimate treatment-related effects on the evaluated cardiovascular measures.

Population Pharmacokinetics of the Interleukin-23 Inhibitor Risankizumab in Subjects with Psoriasis and Crohn's Disease: Analyses of Phase I and II Trials.

BACKGROUND AND OBJECTIVES: Risankizumab is a humanized anti-interleukin-23 monoclonal antibody in development for the treatment of several inflammatory diseases. This work characterized the pharmacokinetics of risankizumab and evaluated covariates that may affect its exposures using phase I and II trial data in subjects with psoriasis and Crohn's disease. METHODS: Plasma concentration measurements from a phase I study and a phase II study in subjects with psoriasis (n = 157; single doses of 0.01-5 mg/kg intravenously, 0.25-1 mg/kg subcutaneously, and 18 mg subcutaneously, and multiple doses of 90 and 180 mg subcutaneously), and a phase II study in subjects with Crohn's disease (n = 115; doses of 200 or 600 mg intravenously every 4 weeks followed by 180 mg subcutaneously every 8 weeks) were analyzed using non-linear mixed-effects modeling. The model was qualified using bootstrap and simulation-based diagnostics. RESULTS: A two-compartment model with first-order absorption and elimination described the pharmacokinetics of risankizumab. Considering the body weight and baseline albumin central tendency differences between disease populations, risankizumab clearance, steady-state volume of distribution, and terminal-phase elimination half-life were estimated to be approximately 0.35 L/day, 11.7 L, and 27 days, respectively, for a typical 90-kg subject with psoriasis with an albumin level of 42 g/L, and 0.31 L/day, 8.45 L, and 22 days, respectively, for a typical 65-kg subject with Crohn's disease with an albumin level of 37 g/L. Risankizumab absolute subcutaneous bioavailability and absorption rate constant were 72% and 0.18 day-1, respectively. Inter-individual variability for clearance was 37%. CONCLUSIONS: Risankizumab displayed pharmacokinetic characteristics typical for an IgG1 monoclonal antibody with no apparent target-mediated disposition. Accounting for the effects of body weight and baseline albumin explained the small differences in the pharmacokinetics of risankizumab between psoriasis and Crohn's disease, with no further differences between the patient populations.

Risankizumab in patients with moderate to severe Crohn's disease: an open-label extension study.

BACKGROUND: Risankizumab, an anti-interleukin 23 antibody, was superior to placebo in achieving clinical and endoscopic remission at week 12 in a randomised, phase 2 induction study in patients with moderately to severely active Crohn's disease. Here we aimed to assess the efficacy and safety of extended intravenous induction and subcutaneous maintenance therapy with risankizumab. METHODS: All patients who completed the 12-week induction phase of the double-blind phase 2 induction study were included in this open-label extension study. Patients who did not achieve deep remission, defined as clinical remission (Crohn's Disease Activity Index [CDAI] <150) and endoscopic remission (Crohn's Disease Endoscopic Index of Severity [CDEIS] ≤4, or ≤2 for patients with isolated ileitis), at week 12 received open-label intravenous therapy with 600 mg risankizumab every 4 weeks for 12 weeks; patients in deep remission at week 12 entered a 12-week washout phase. Patients in clinical remission at week 26 were invited to participate in the maintenance phase of the study, in which they received open-label subcutaneous risankizumab (180 mg) every 8 weeks for 26 weeks. 26-week efficacy endpoints were the proportion of patients in clinical remission (CDAI <150), and the proportion of patients who achieved clinical response (either CDAI of <150 or a reduction from baseline of at least 100 points). 52-week efficacy endpoints were the proportion of patients achieving: clinical remission; clinical response; endoscopic response (>50% CDEIS reduction from baseline); endoscopic remission, as defined previously; mucosal healing; and deep remission. Safety was assessed in patients who received at least one dose of the study drug during the open-label phases of the study. This study is registered with ClinicalTrials.gov, number NCT02031276. FINDINGS: Of the 108 patients who completed the 12-week double-blind induction trial, six patients were in deep remission and entered the 12-week washout phase. 102 patients were not in deep remission, 101 of whom received 12 weeks of 600 mg risankizumab (33 from the original placebo group, 34 from the 200 mg risankizumab group, and 34 from the 600 mg risankizumab group); the other patient declined to continue the study. At week 26, 54 (53%) of 101 patients treated with 600 mg rizankizumab were in clinical remission. Among patients included in the open-label extension trial, clinical remission rates at week 26 versus week 12 were: 18 (55%) versus six (18%) of 33 patients in the original placebo group; 20 (59%) versus seven (21%) of 34 patients in the original 200 mg risankizumab group; and 16 (47%) versus nine (26%) of 34 patients in the original 600 mg risankizumab group. 62 patients received risankizumab maintenance treatment, including the 54 patients who achieved clinical remission at week 26, the six patients who had achieved deep remission at week 12, and one patient because of a protocol violation. At week 52, clinical remission was maintained in 44 (71%) patients; 50 (81%) patients had a clinical response, 22 (35%) patients were in endoscopic remission, and 34 (55%) patients had an endoscopic response. 15 (24%) patients had mucosal healing and 18 (29%) patients achieved deep remission at week 52. Risankizumab was well tolerated with no new safety signals noted. The most frequent treatment-emergent adverse events were arthralgia (25 [22%] of 115 patients), headache (23 [20%]), abdominal pain (21 [18%]), nasopharyngitis (18 [16%]), nausea (18 [16%]), and pyrexia (15 [13%]). Most adverse events were mild or moderate and considered to be unrelated to study treatment. There were no treatment-related deaths. INTERPRETATION: Extended induction treatment with open-label intravenous risankizumab was effective in increasing clinical response and remission rates at week 26. Open-label subcutaneous risankizumab maintained remission until week 52 in most patients who were in clinical remission at week 26. Selective blockade of interleukin 23 warrants further investigation as a treatment for Crohn's disease. FUNDING: Boehringer Ingelheim.

Pharmacokinetics of the B-Cell Lymphoma 2 (Bcl-2) Inhibitor Venetoclax in Female Subjects with Systemic Lupus Erythematosus.

BACKGROUND AND OBJECTIVE: Venetoclax is an oral selective Bcl-2 inhibitor approved for the treatment of patients with chronic lymphocytic leukemia with 17p deletion. Mechanistic and preclinical evidence warranted evaluation of venetoclax for the treatment of systemic lupus erythematosus (SLE). This work characterized the pharmacokinetics of venetoclax in female subjects with SLE. METHODS: Single (10-500 mg) and multiple (30-600 mg) escalating doses of venetoclax or matching placebo were evaluated using randomized, double-blind, placebo-controlled designs (6 active and 2 placebo per dose with 73 unique SLE patients enrolled, 25 of whom enrolled twice). The multiple-dose evaluation consisted of two cycles, each with once-daily dosing for 7 days followed by a 21-day washout. Non-compartmental and population pharmacokinetic analyses of venetoclax serial plasma concentrations were conducted. RESULTS: Venetoclax exhibited approximately dose-proportional exposures, with peak concentrations observed 4-8 h post-dose. Venetoclax steady-state exposures were achieved by day 4 of dosing, and the median area under the plasma concentration-time curve (AUC) accumulation ratio ranged from 1.1 to 1.5. A two-compartment model with first-order absorption and elimination described venetoclax pharmacokinetics. The estimates (95% bootstrap confidence interval) for venetoclax apparent clearance, central and peripheral volumes of distribution, intercompartmental clearance, absorption rate constant, and lag time were 16.3 L/h (14.6-17.9), 37 L (26-57), 122 L (98-183), 3.7 L/h (2.6-5.0), 0.13 h-1 (0.11-0.17), and 1.6 h (1.6-1.7), respectively. The population estimate for venetoclax terminal-phase elimination half-life was approximately 28 h. CONCLUSIONS: In female subjects with SLE, venetoclax displayed pharmacokinetic characteristics consistent with previous observations in subjects with hematologic malignancies. CLINICALTRIALS. GOV IDENTIFIER: NCT01686555.

Application of Exposure-Response Analyses to Establish the Pharmacodynamic Similarity of a Once-Daily Regimen to an Approved Twice-Daily Dosing Regimen for the Treatment of HCV Infection.

The triple direct-acting antiviral (3-DAA) regimen (two co-formulated tablets of ombitasvir/paritaprevir/ritonavir once daily and one tablet of dasabuvir twice daily) for patients with hepatitis C virus (HCV) genotype 1 infection has been reformulated for once-daily administration containing all three active DAAs (3QD regimen). Two bioequivalence studies compared the 3-DAA and 3QD regimens. In study 1, fed, single-, and multiple-dose crossover comparisons revealed exposures for drug components that were slightly outside the bioequivalence criteria, i.e., 21 to 29% lower dasabuvir C trough, paritaprevir C max, and ritonavir C max. In study 2, fed and fasted single-dose crossover comparisons demonstrated a large impact of food on exposures, confirming the product's labeling requirement for administration only with food, and revealed a lack of bioequivalence under fasting conditions. Exposure-response analyses using efficacy data from phase 2/3 studies of the 3-DAA regimen demonstrated that the lower dasabuvir C trough for the 3QD regimen (under fed condition) would have minimal impact on sustained virologic response at week 12 post-treatment (SVR12). Thus, the pharmacodynamic similarity between the regimens was established and the analyses provided the basis for regulatory approval of the 3QD regimen to treat patients with chronic HCV genotype 1 infection.

Blockade of the High-Affinity Interleukin-2 Receptors with Daclizumab High-Yield Process: Pharmacokinetic/Pharmacodynamic Analysis of Single- and Multiple-Dose Phase I Trials.

BACKGROUND AND OBJECTIVE: Daclizumab high-yield process (DAC HYP) is a humanized monoclonal antibody that selectively blocks the α-subunit (CD25) of the high-affinity interleukin-2 receptors, and has shown robust efficacy as a treatment for multiple sclerosis (MS). This work quantitatively characterized the relationship between DAC HYP serum concentrations and saturation of CD25 expressed on antigen-rich target T cells in blood. METHODS: Serial pharmacokinetic and 968 CD25 measurements from three double-blind, randomized, placebo-controlled, phase I studies of DAC HYP (50-300 mg subcutaneous and 200-400 mg intravenous doses or placebo) in healthy volunteers (n = 95) were analyzed using nonlinear mixed-effects modeling. CD25 occupancy was determined using flow cytometry and a fluorescently-labeled DAC HYP-competing antibody. RESULTS: CD25 occupancy was described using a direct inhibitory sigmoidal maximum effect (E max) model (where DAC HYP fully inhibited CD25 labeling with competing antibody). Two IC50 (serum concentration corresponding to 50 % of maximal inhibition) parameters were used to describe rapid CD25 saturation at initiation of dosing and apparently slower desaturation during DAC HYP washout. Parameter estimates (95 % bootstrap confidence intervals) were: baseline CD25 labeling, 47 % (45-48); DAC HYP IC50(saturation), 0.023 µg/mL (0.005-0.073); IC50(desaturation) 0.86 µg/mL (0.74-0.98); Hill coefficient 5.6 (4.3-6.8). CONCLUSIONS: Based on the developed model, the 150 mg monthly subcutaneous regimen of DAC HYP in subjects with MS is predicted to saturate CD25 on target effector T cells within a few hours of dosing and maintain CD25 saturation during the entire dosing interval. Free CD25 levels return to baseline within 4-6 months of the last DAC HYP dose.

Novel dexamethasone-loaded nanomicelles for the intermediate and posterior segment uveitis.

Development and characterization of dexamethasone (DEX)-encapsulated polymeric nanomicelles have been reported. A low molecular weight di-block copolymer was synthesized and characterized for its structure, molecular weights, critical micelle concentration (CMC), and cytotoxicity in ocular cells. In order to delineate the effects of drug-polymer interactions on drug solubilization in micelle core, a response surface methodology was generated with the help of SAS 9.02 (exploratory model). The method for preparing micelle was modified based on the results obtained from exploratory model. The formulation was optimized by response surface methodology (optimization model) to achieve DEX solubility of above 1 mg/mL. The optimized formulation was characterized for DEX solubility, nanomicelle size, polydispersity index, surface morphology, in vitro transport across conjunctival cell line, and ex vivo transport across excised rabbit sclera. Nanomicelles exhibited average sizes in range of 25-30 nm with unimodel size distribution and low polydispersity of 0.125. Nanomicelles increased DEX permeability by 2 times across conjunctival cell line and by 2.5 times across the excised rabbit sclera as compared to DEX suspension. A design of experiment (DOE) strategy was successfully applied to understand the effects of drug-polymer interaction on drug solubility. DOE was also employed to achieve optimal formulation with high DEX solubility. Nanomicellar formulation significantly enhanced DEX permeability across the excised rabbit sclera. Therefore, nanomicellar formulation may provide therapeutic levels in the back of the eye following topical administration.

Inhibition of OATP-1B1 and OATP-1B3 by tyrosine kinase inhibitors.

BACKGROUND: The potential of tyrosine kinase inhibitors (TKIs) interacting with other therapeutics through hepatic uptake transporter inhibition has not been fully delineated in drug-drug interactions (DDIs). This study was designed to estimate the half-maximal inhibitory concentration (IC50) values of five small-molecule TKIs (pazopanib, nilotinib, vandetanib, canertinib and erlotinib) interacting with organic anion-transporting polypeptides (OATPs): OATP-1B1 and -1B3. METHODS: The IC50 values of TKIs and rifampicin (positive control) were determined by concentration-dependent inhibition of TKIs on cellular accumulation of radiolabeled probe substrates [3H]estrone sulfate and [3H]cholecystokinin octapeptide. Chinese hamster ovary cells transfected with humanized OATP-1B1 and OATP-1B3 transporter proteins, respectively, were utilized to carry out these studies. RESULTS: Pazopanib and nilotinib show inhibitory activity on OATP-1B1 transporter protein. IC50 values for rifampicin, pazopanib and nilotinib were 10.46±1.15, 3.89±1.21 and 2.78±1.13 µM, respectively, for OATP-1B1 transporter. Vandetanib, canertinib and erlotinib did not exhibit any inhibitory potency toward OATP-1B1 transporter protein. Only vandetanib expressed inhibitory potential toward OATP-1B3 transporter protein out of the five selected TKIs. IC50 values for rifampicin and vandetanib for OATP-1B3 transporter inhibition were 3.67±1.20 and 18.13±1.21 µM, respectively. No significant inhibition in the presence of increasing concentrations of pazopanib, nilotinib, canertinib and erlotinib were observed for OATP-1B3 transporter. CONCLUSIONS: Because selected TKIs are inhibitors of OATP-1B1 and -1B3 expressed in hepatic tissue, these compounds can be regarded as molecular targets for transporter-mediated DDIs. These findings provide the basis for further preclinical and clinical studies investigating the transporter-based DDI potential of TKIs.

Drug Development and Potential Regulatory Paths for Insulin Biosimilars.

Under the Biologics Price Competition and Innovation Act (BPCI Act), a biological product may be demonstrated to be "biosimilar" if data show that, among other things, the product is "highly similar" to an already-approved biological product. Biosimilar insulins have the potential to reduce ever growing costs associated with insulin treatment by allowing competition. In this article, we describe the current drug development and regulatory paths for biosimilar insulins. Most likely basis of market approval for biosimilar insulins by the US Food and Drug Administration (FDA) and guidance for developing insulin biosimilars by European Medicines Agency (EMA) are discussed in detail. Currently, no product specific biosimilar FDA guidance for insulin biosimilarity assessment exists. We propose efficient and cost-effective drug development and potential regulatory paths based on scientific justification. In addition, novel trial designs for demonstrating interchangeability between the biosimilar and the reference insulin products are presented.

Role of OATP-1B1 and/or OATP-1B3 in hepatic disposition of tyrosine kinase inhibitors.

BACKGROUND: The metabolism of tyrosine kinase inhibitors (TKIs) is mainly mediated via hepatic route, but the mechanism responsible for their hepatocellular accumulation is still unknown. This study was designed to understand the contribution of organic anion transporting polypeptides (OATPs) in the hepatic uptake of selected TKIs - pazopanib, canertinib, erlotinib, vandetanib and nilotinib. METHODS: Michaelis-Menten (MM) kinetic parameters for TKIs were determined by concentration-dependent cellular accumulation of selected TKIs using Chinese hamster ovary cells - wild type as well as transfected with humanized OATP-1B1 and OATP-1B3 transporter proteins. RESULTS: The MM constant (Km) values of OATP-1B1 for nilotinib and vandetanib are 10.14±1.91 and 2.72±0.25 µM, respectively, and Vmax values of OATP-1B1 for nilotinib and vandetanib were 6.95±0.47 and 75.95±1.99 nmol/mg protein per minute, respectively. Likewise, Km values of OATP-1B3 for canertinib, nilotinib and vandetanib were 12.18±3.32, 7.84±1.43 and 4.37±0.79 µM, respectively, and Vmax values of OATP-1B3 for canertinib, nilotinib and vandetanib were 15.34±1.59, 6.75±0.42 and 194.64±10.58 nmol/mg protein per minute, respectively. Canertinib did not exhibit any substrate specificity toward OATP-1B1. Also, erlotinib and pazopanib did not exhibit any substrate specificity toward OATP-1B1 and -1B3. CONCLUSIONS: Because selected TKIs are the substrates of OATP-1B1 and -1B3 expressed in hepatic tissue, these compounds can be regarded as molecular targets for transporter-mediated drug-drug interactions (DDIs). Any alteration in the function of these hepatic OATPs might account for the pharmacokinetic variability of TKIs.

Determination of pazopanib (GW-786034) in mouse plasma and brain tissue by liquid chromatography-tandem mass spectrometry (LC/MS-MS).

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC/MS-MS) method has been developed and validated for the quantitative determination of pazopanib in mouse plasma and brain tissue homogenate. Single liquid-liquid extraction step with ethyl acetate was employed for analysis of pazopanib and the internal standard (IS); vandetanib. HPLC separation was performed on an XTerra(®) MS C18 column 50 mm × 4.6 mm, 5.0 µm. The mobile phase consisted of 70% acetonitrile and 30% water with 0.1% formic acid, pumped at a flow rate of 0.25 ml/min. Analysis time was 3.5 min per run and both the analyte and IS eluted within 1.8-2.0 min. Multiple reactions monitoring (MRM) mode was utilized to detect the compounds of interest. The mass spectrometer was operated in the positive ion mode for detection. The precursor to product ions (Q1→Q3) selected for pazopanib and internal standard during quantitative optimization were (m/z) 438.1→357.2 and 475.0→112.2 respectively. The calibration curves were linear over the range of 3.9-1000 ng/ml in both biological matrices. Lower limit of quantification (LLOQ) for mouse plasma and brain tissue was 3.9 ng/ml. The values for inter and intra day precision and accuracy were well within the ranges acceptable for analytical assessment (<15%). This method was applied to determine brain to plasma concentration ratio and relevant pharmacokinetic parameters of pazopanib after a single intravenous dose of 5 mg/kg in FVB wild type mice.

Enhanced brain accumulation of pazopanib by modulating P-gp and Bcrp1 mediated efflux with canertinib or erlotinib.

Primary objective of this investigation was to delineate the differential impact of efflux transporters P-glycoprotein (P-gp/Abcb1) and breast cancer resistance protein (Bcrp1/Abcg2) on brain disposition and plasma pharmacokinetics of pazopanib. In addition, this research investigated whether inhibition of these efflux transporters with clinically relevant efflux modulators canertinib or erlotinib could be a viable strategy for improving pazopanib brain delivery. In vitro assays with MDCKII cell monolayers suggested that pazopanib is a high affinity substrate for Bcrp1 and a moderate substrate for P-gp. Co-incubation with specific transport inhibitors restored cell accumulation and completely abolished the directionality of pazopanib flux. Brain and plasma pharmacokinetic studies were conducted in FVB wild type mice in the absence and presence of specific transport inhibitors. Drug levels in plasma and brain were determined using a validated high performance liquid chromatography method using vandetanib as an internal standard. In vivo studies indicated that specific inhibition of either P-gp (by zosuquidar or LY335979) or Bcrp1 (by Ko143) alone did not significantly alter pazopanib brain accumulation. However, dual P-gp/Bcrp1 inhibition by elacridar (GF120918), significantly enhanced pazopanib brain penetration by ~5-fold without altering its plasma concentrations. Thus, even though Bcrp1 showed higher affinity towards pazopanib in vitro, in vivo at the mouse BBB both P-gp and Bcrp1 act in concert to limit brain accumulation of pazopanib. Furthermore, erlotinib and canertinib as clinically relevant efflux modulators efficiently abrogated directionality in pazopanib efflux in vitro and their co-administration resulted in 2-2.5-fold increase in pazopanib brain accumulation in vivo. Further pre-clinical and clinical investigations are warranted as erlotinib or canertinib may have a synergistic pharmacological effect in addition to their primary role of pazopanib efflux modulation as a combination regimen for the treatment of recurrent brain tumors.

Co-administration strategy to enhance brain accumulation of vandetanib by modulating P-glycoprotein (P-gp/Abcb1) and breast cancer resistance protein (Bcrp1/Abcg2) mediated efflux with m-TOR inhibitors.

The objectives of this study were (i) to characterize the interaction of vandetanib with P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp1) in vitro and in vivo (ii) to study the modulation of P-gp and BCRP mediated efflux of vandetanib with specific transport inhibitors and m-TOR inhibitors, everolimus and temsirolimus. Cellular accumulation and bi-directional transport studies in MDCKII cell monolayers were conducted to delineate the role of efflux transporters on disposition of vandetanib. Brain distribution studies were conducted in male FVB wild-type mice with vandetanib administered intravenously either alone or in the presence of specific inhibitors and m-TOR inhibitors. In vitro studies suggested that vandetanib is a high affinity substrate of Bcrp1 but is not transported by P-gp. Interestingly, in vivo brain distribution studies in FVB wild type mice indicated that vandetanib penetration into the brain is restricted by both Bcrp1 and P-gp mediated active efflux at the blood brain barrier (BBB). Co-administration of elacridar, a dual P-gp/BCRP inhibitor increased the brain to plasma concentration ratio of vandetanib upto 5 fold. Of the two m-TOR pathway inhibitors examined; everolimus showed potent effect on modulating vandetanib brain penetration whereas no significant affect on vandetanib brain uptake was observed following temsirolimus co-administration. This finding could be clinically relevant as everolimus can provide synergistic pharmacological effect in addition to primary role of vandetanib efflux modulation at BBB for the treatment of brain tumors.

Effect of short term and chronic administration of Sutherlandia frutescens on pharmacokinetics of nevirapine in rats.

Sutherlandia frutescens (sutherlandia), an African herbal supplement was recommended by the South African Ministry of Health for the treatment of AIDS patients. However, no reports yet exist delineating the effect of sutherlandia on pharmacokinetics of antiretroviral agents. Therefore, this investigation aimed at screening the effects of short term and chronic exposure of sutherlandia on oral bioavailability and pharmacokinetics of nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, in Sprague Dawley rats. NVP (6 mg/kg) was administered orally alone (control) and with co-administration of sutherlandia; short term (12 mg/kg single dose) and long term (12 mg/kg, once a day for 5 days). No significant difference in the pharmacokinetic parameters of NVP was found upon short-term co-administration of Sutherlandia. However, there was a 50% decrease (p<0.05) in the AUC and C(max) values of NVP after 5 days of chronic exposure with Sutherlandia. In addition, quantitative RT-PCR studies demonstrated a 2-3-fold increase in the hepatic and intestinal mRNA expression of CYP3A2, relative to vehicle control. To further confirm, if this could translate into a clinically relevant pharmacokinetic interaction in patients, we tested this hypothesis employing LS-180 cells as an in vitro induction model for human CYP3A4. Ninety-six hours post treatment, similar to positive control rifampicin (25 µM), sutherlandia extract (300 µg/mL) resulted in elevated m-RNA expression levels and functional activity of CYP3A4 (human homologue of rodent CYP3A2) in LS-180 cells. Taken together, these results suggest that a potential drug-herb interaction is possible when NVP is co-administered with S. frutescens, although this hypothesis still remains to be investigated in a clinical setting.