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Tisotumab vedotin is an investigational antibody-drug conjugate (ADC) for treatment of solid tumors expressing tissue factor with accelerated approval from the US Food and Drug Administration for treatment of recurrent or metastatic cervical cancer with disease progression during or after chemotherapy. This study describes development of a population pharmacokinetic (PK) model to assess the PK profile of tisotumab vedotin and microtubule-disrupting agent monomethyl auristatin E (MMAE) using data from 399 patients with solid tumors across four phase I/II trials. The ADC-MMAE model describes ADC and MMAE concentrations following intravenous administration of tisotumab vedotin. This four-compartment model comprises a two-compartment ADC model with parallel linear and Michaelis-Menten elimination, a delay compartment, and a one-compartment MMAE model. Nonspecific linear clearance of ADC was 1.42 L/day, central volume of distribution (V

Supplemental tables and figures Supplemental Table 1. Study drug exposure. Supplemental Table 2. Select AEs at relatively high frequency led to disproportionately more frequent irinotecan/5-FU dose changes (reduced, interrupted, or withdrawn) on the duligotuzumab arm. Supplemental Figure 1. CONSORT patient flow diagram

Purpose: Duligotuzumab is a dual-action antibody directed against EGFR and HER3.Experimental Design: Metastatic colorectal cancer (mCRC) patients with KRAS ex2 wild-type received duligotuzumab or cetuximab and FOLFIRI until progression or intolerable toxicity. Mandatory tumor samples underwent mutation and biomarker analysis. Efficacy analysis was conducted in patients with RAS exon 2/3 wild-type tumors.Results: Of 134 randomly assigned patients, 98 had RAS ex2/3 wild-type. Duligotuzumab provided no progression-free survival (PFS) or overall survival (OS) benefit compared with cetuximab, although there was a trend for a lower objective response rate (ORR) in the duligotuzumab arm. No relationship was seen between PFS or ORR and ERBB3, NRG1, or AREG expression. There were fewer skin rash events for duligotuzumab but more diarrhea. Although the incidence of grade ≥3 AEs was similar, the frequency of serious AEs was higher for duligotuzumab.Conclusions: Duligotuzumab plus FOLFIRI did not appear to improve the outcomes in patients with RAS exon 2/3 wild-type mCRC compared with cetuximab + FOLFIRI. Clin Cancer Res; 24(10); 2276–84. ©2018 AACR.

Purpose: Insulin-like growth factor-1 receptor (IGF-1R) mediates cellular processes in cancer and has been proposed as a therapeutic target. Dalotuzumab (MK-0646) is a humanized IgG1 monoclonal antibody that binds to IGF-1R preventing receptor activation. This study was designed to evaluate the safety and tolerability of dalotuzumab, determine the pharmacokinetic (PK) and pharmacodynamic (PD) profiles, and identify a recommended phase II dose.Experimental Design: Patients with tumors expressing IGF-1R protein were allocated to dose-escalating cohorts of three or more patients each and received intravenous dalotuzumab weekly, every 2 or 3 weeks. Plasma was collected for PK analysis. Paired baseline and on-treatment skin and tumor biopsy samples were collected for PD analyses.Results: Eighty patients with chemotherapy-refractory solid tumors were enrolled. One dose-limiting toxicity was noted, but a maximum-tolerated dose was not identified. Grade 1 to 3 hyperglycemia, responsive to metformin, occurred in 15 (19%) patients. At dose levels or more than 5 mg/kg, dalotuzumab mean terminal half-life was 95 hours or more, mean Cmin was more than 25 μg/mL, clearance was constant, and serum exposures were approximately dose proportional. Decreases in tumor IGF-1R, downstream receptor signaling, and Ki67 expression were observed. 18F-Fluorodeoxy-glucose positron emission tomography metabolic responses occurred in three patients. One patient with Ewing's sarcoma showed a mixed radiologic response. The recommended phase II doses were 10, 20, and 30 mg/kg for the weekly, every other week, and every third week schedules, respectively.Conclusions: Dalotuzumab was generally well-tolerated, exhibited dose-proportional PK, inhibited IGF-1R pathway signaling and cell proliferation in treated tumors, and showed clinical activity. The low clearance rate and long terminal half-life support more extended dosing intervals. Clin Cancer Res; 17(19); 6304–12. ©2011 AACR.

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SEA-TGT is a human nonfucosylated monoclonal antibody (mAb) targeting the T cell immunoreceptor with immunoglobulin (Ig) and ITIM domains (TIGIT) protein. TIGIT is an immunoregulatory receptor expressed on activated and memory T cells, Tregs, and NK cells. TIGIT binding to CD155 and CD112 on tumor cells drives an inhibitory signal resulting in decreased T cell functionality. TIGIT targeting has been reported to release these inhibitory signals, drive Treg depletion, augment CD8+ T cell generation, and promote anti-tumor responses. SGNTGT-001 (NCT04254107) is a phase 1 clinical trial that evaluated the safety and tolerability of SEA-TGT as monotherapy in solid tumors and lymphomas at doses ranging from 0.01 to 6 mg/kg. Because an MTD was not identified in dose escalation, pharmacokinetic (PK) and pharmacodynamic (PD) endpoints were measured to assess biological activity and inform dose selection. The biological activity of SEA-TGT as monotherapy was compared across different dose levels using a clinical utility index (CUI), which mathematically integrated multiple clinically-meaningful PK and PD endpoints into a single readout. PD endpoints included NK and CD8+ T cell proliferation, maintenance of overall peripheral CD8+ T cell numbers, depletion of peripheral regulatory T cells, and peripheral target engagement. The PK endpoint was pharmacokinetic linearity. Surrogates of predicted tumor efficacy metrics included tumor target engagement and formation of the TIGIT:SEA-TGT:Fc receptor gamma (FcγRIIIa) trimer complexes in the tumor. An increase in the CUI score, representing an increase in biological activity, was observed during dose escalation, with an apparent plateau between the 0.3 and 6.0 mg/kg levels. Based on safety signals at 6 mg/kg and PK variability at lower doses, 1 and 3 mg/kg were of most interest for further evaluation. Both 1 and 3 mg/kg represented biologically active dose levels as they showed PK and PD activity that were within desirable ranges and had similarly high overall CUI scores relative to all doses evaluated. Dose selection for SEA-TGT was based on biological activity as assessed via PK/PD endpoints and integrated into a CUI model. Based on the totality of clinical data and the CUI results from monotherapy dose escalation from SGNTGT-001, the SEA-TGT dose of 1 mg/kg was determined to be the lowest biologically active dose with acceptable safety and tolerability. Citation Format: Gabriela Patilea-Vrana, John Harrold, Joseph A. Ware, Shaparak Lonning, Hun Lee, Lisa Brooks, Haley Neff-LaFord, William D. Hanley, Andres Forero-Torres. Using clinical utility index (CUI) to determine the optimal biological dose of a nonfucosylated anti-TIGIT antibody: A proposed alternative to maximum tolerated dose (MTD). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5668.

MHAA4549A is a human anti‐influenza A monoclonal antibody developed to treat influenza A. We report MHAA4549A serum, nasopharyngeal, and tracheal aspirate pharmacokinetics from a phase 2b study in hospitalized patients with severe influenza A. Patients were randomized 1:1:1 into 3 groups receiving single intravenous doses of 3600 mg (n = 55) or 8400 mg (n = 47) MHAA4549A or placebo (n = 56). Patients also received oral oseltamivir twice daily for ≥5 days. Serum, nasopharyngeal, and tracheal aspirate pharmacokinetic samples were collected on days 1‐60 from MHAA4549A‐treated groups. Day 5 plasma samples from all groups were collected for assessing the pharmacokinetics of oseltamivir and its active metabolite, oseltamivir carboxylate. Noncompartmental pharmacokinetic analysis was performed using Phoenix WinNonlin. Data were collected during a preplanned interim analysis that became final when the trial terminated because of a lack of efficacy. Serum MHAA4549A concentrations were dose‐proportional and biphasic. Mean MHAA4549A clearance was 288‐350 mL/day, and mean half‐life was 17.8‐19.0 days. Nasopharyngeal MHAA4549A concentrations were non‐dose‐proportional. We detected MHAA4549A in tracheal aspirate samples, but intersubject variability was high. MHAA4549A serum and nasopharyngeal exposures were confirmed in all MHAA4549A‐treated patients. Serum MHAA4549A had faster clearance and a shorter half‐life in influenza A‐infected patients compared with healthy subjects. MHAA4549A detection in tracheal aspirate samples indicated exposure in the lower respiratory tract. Oseltamivir and oseltamivir carboxylate exposures were similar between MHAA4549A‐treated and placebo groups, suggesting a lack of MHAA4549A interference with oseltamivir pharmacokinetics.

Treatment of individuals coinfected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) requires careful consideration of potential drug-drug interactions. We evaluated the pharmacokinetic interaction of the direct-acting antiviral agents elbasvir and grazoprevir coadministered with the nucleotide reverse transcriptase inhibitor tenofovir disoproxil fumarate (TDF). Three open-label, multidose studies in healthy adults were conducted. In the first study (N = 10), participants received TDF 300 mg once daily, elbasvir 50 mg once daily, and elbasvir coadministered with TDF. In the second study (N = 12), participants received TDF 300 mg once daily, grazoprevir 200 mg once daily, and grazoprevir coadministered with TDF. In the third study (N = 14), participants received TDF 300 mg once daily and TDF 300 mg coadministered with coformulated elbasvir/grazoprevir 50 mg/100 mg once daily. Pharmacokinetics and safety were evaluated. Following coadministration, the tenofovir area under the plasma concentration-time curve to 24 hours and maximum plasma concentration geometric mean ratios (90% confidence intervals) for tenofovir and coadministered drug(s) versus tenofovir were 1.3 (1.2, 1.5) and 1.5 (1.3, 1.6), respectively, when coadministered with elbasvir; 1.2 (1.1, 1.3) and 1.1 (1.0, 1.2), respectively, when coadministered with grazoprevir; and 1.3 (1.2, 1.4) and 1.1 (1.0, 1.4), respectively, when coadministered with the elbasvir/grazoprevir coformulation. TDF had minimal effect on elbasvir and grazoprevir pharmacokinetics. Elbasvir and/or grazoprevir coadministered with TDF resulted in no clinically meaningful tenofovir exposure increases and was generally well tolerated, with no deaths, serious adverse events (AEs), discontinuations due to AEs, or laboratory AEs reported. No dose adjustments for elbasvir/grazoprevir or TDF are needed for coadministration in HCV/HIV-coinfected people.

Purpose To evaluate the safety and efficacy of the Port Delivery System with ranibizumab (PDS) for neovascular age-related macular degeneration (nAMD) treatment. Design Phase 2, multicenter, randomized, active treatment–controlled clinical trial. Participants Patients diagnosed with nAMD within 9 months who had received 2 or more prior anti–vascular endothelial growth factor intravitreal injections and were responsive to treatment. Methods Patients were randomized 3:3:3:2 to receive the PDS filled with ranibizumab 10 mg/ml, 40 mg/ml, 100 mg/ml, or monthly intravitreal ranibizumab 0.5-mg injections. Main Outcome Measures Time to first implant refill assessed when the last enrolled patient completed the month 9 visit (primary efficacy end point), improvement in best-corrected visual acuity (BCVA) and central foveal thickness (CFT), and safety. Results The primary analysis population was 220 patients, with 58, 62, 59, and 41 patients in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. Median time to first implant refill was 8.7, 13.0, and 15.0 months in the PDS 10-mg/ml, PDS 40-mg/ml, and PDS 100-mg/ml arms, respectively. At month 9, the adjusted mean BCVA change from baseline was ‒3.2 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, ‒0.5 ETDRS letters, +5.0 ETDRS letters, and +3.9 ETDRS letters in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. At month 9, the adjusted mean CFT change from baseline was similar in the PDS 100-mg/ml and monthly intravitreal ranibizumab 0.5-mg arms. The optimized PDS implant insertion and refill procedures were generally well tolerated. After surgical procedure optimization, postoperative vitreous hemorrhage rate was 4.5% (7/157; 1 event classified as serious). There was no evidence of implant clogging. Conclusions In the phase 2 Ladder trial, the PDS was generally well tolerated and demonstrated a dose response across multiple end points in patients with nAMD. The PDS 100-mg/ml arm showed visual and anatomic outcomes comparable with monthly intravitreal ranibizumab 0.5-mg injections but with a reduced total number of ranibizumab treatments. The PDS has the potential to reduce treatment burden in nAMD while maintaining vision.

568 Background: Enfortumab vedotin (EV) is an antibody-drug conjugate comprised of a fully human monoclonal antibody directed against Nectin-4 and monomethyl auristatin E (MMAE), a microtubule-disrupting agent, attached to the antibody via a protease-cleavable linker. EV is approved in the US for treatment of adult patients (pts) with locally advanced/metastatic urothelial carcinoma (la/mUC) who previously received a PD-1/L1 inhibitor and platinum-based chemotherapy, and who are ineligible for cisplatin-based chemotherapy and previously received 1+ lines of therapy. In EV-301, EV significantly reduced risk of death by 30% vs chemotherapy in pts with treated la/mUC. Data from five clinical studies (N = 748) were used to describe the clinical pharmacology of EV. Methods: Pharmacokinetics (PK) of EV and free MMAE were studied in pts with la/mUC (n = 699) and malignant solid tumors receiving EV in phase 1, 2, and 3 studies. EV and MMAE PK parameters were calculated with non-compartmental analysis. Population PK analysis was used to characterize/assess impact of covariates on EV and MMAE PK. Antitherapeutic antibodies (ATA) were assessed in all studies. Results: EV 0.5 to 1.25 mg/kg IV on Days 1, 8, and 15 of a 28-day cycle showed linear, dose-proportional PK. Mean EV and MMAE clearance was 0.110 and 2.11 L/h, respectively; elimination t1/2 was 3.6 and 2.6 days. Steady state was reached by Cycle 1; accumulation was limited for EV and MMAE between cycles. EV PK differences in special populations were not considered clinically meaningful. For renal impairment, no significant differences in exposure of EV and MMAE were observed in mild (n = 272), moderate (n = 315), or severe (n = 25) impairment vs normal renal function. For hepatic impairment, bilirubin was a significant covariate for MMAE only; pts with mild impairment (n = 65) had a 37% increase in AUC0-28d and 31% increase in Cmax of MMAE vs pts with normal hepatic function. No clinically significant differences in EV and MMAE PK were observed based on age (range, 24-90 yrs; > 65 yrs, 60%), sex (male, 73%), or race/ethnicity (White, 69%; Asian, 21%; Black, 1%; others/unknown, 8%). Weight-based dosing showed similar exposure for all pts. EV did not prolong mean QTc interval to a clinically relevant extent per ECG/PK data from the EV-102 study (n = 17; advanced UC). Concomitant use with dual P-gp and strong CYP3A4 inhibitors may increase MMAE exposure and may increase the risk of adverse events. Following EV 1.25 mg/kg, 16/590 (2.7%) pts tested positive for ATA against EV at ≥1 postbaseline time point. Conclusions: Integration of EV and free MMAE PK findings support the EV dose of 1.25 mg/kg on Days 1, 8, and 15 of a 28-day cycle. No dose adjustments were required for special populations or by age, sex, or race. Caution is advised during concomitant treatment with strong CYP3A4 inhibitors, and a low rate of immunogenicity was observed.

Purpose: Duligotuzumab is a dual-action antibody directed against EGFR and HER3. Experimental Design: Metastatic colorectal cancer (mCRC) patients with KRAS ex2 wild-type received duligotuzumab or cetuximab and FOLFIRI until progression or intolerable toxicity. Mandatory tumor samples underwent mutation and biomarker analysis. Efficacy analysis was conducted in patients with RAS exon 2/3 wild-type tumors. Results: Of 134 randomly assigned patients, 98 had RAS ex2/3 wild-type. Duligotuzumab provided no progression-free survival (PFS) or overall survival (OS) benefit compared with cetuximab, although there was a trend for a lower objective response rate (ORR) in the duligotuzumab arm. No relationship was seen between PFS or ORR and ERBB3, NRG1, or AREG expression. There were fewer skin rash events for duligotuzumab but more diarrhea. Although the incidence of grade ≥3 AEs was similar, the frequency of serious AEs was higher for duligotuzumab. Conclusions: Duligotuzumab plus FOLFIRI did not appear to improve the outcomes in patients with RAS exon 2/3 wild-type mCRC compared with cetuximab + FOLFIRI. Clin Cancer Res; 24(10); 2276–84. ©2018 AACR.

This study aims at evaluating the utility of the population pharmacokinetics approach in therapeutic protein drug-drug-interaction (DDI) assessment. Simulations were conducted for 2 representative victim drugs, methotrexate and trastuzumab, using a parallel-group design with and without the interaction drug. The effect of a perpetrator on the exposure of the victim drug is described as the ratio of clearance/apparent clearance of the victim drug given with or without the perpetrator. The power of DDI assessment was calculated as the percentage of runs with 90% confidence interval of the estimated DDI effect within 80% to 125% for the scenarios of no DDI, benchmarked with the noncompartmental approach with intensive sampling. The impact of the number of subjects, the number of sampling points per subject, sampling time error, and model misspecification on the power of DDI determination were evaluated. Results showed that with equal numbers of subjects in each arm, the population pharmacokinetics approach with sparse sampling may need about the same or a higher number of subjects compared to a noncompartmental approach in order to achieve similar power. Increasing the number of subjects, even if only in the study drug alone arm, can increase the power. Sampling or dosing time error had notable impacts on the power for methotrexate but not for trastuzumab. Model misspecification had no notable impacts on the power for trastuzumab. Overall, the population pharmacokinetics approach with sparse sampling built in phase 2/3 studies allows appropriate DDI assessment with adequate study design and analysis and can be considered as an alternative to dedicated DDI studies.

To evaluate the safety and efficacy of the Port Delivery System with ranibizumab (PDS) for neovascular age-related macular degeneration (nAMD) treatment.Phase 2, multicenter, randomized, active treatment-controlled clinical trial.Patients diagnosed with nAMD within 9 months who had received 2 or more prior anti-vascular endothelial growth factor intravitreal injections and were responsive to treatment.Patients were randomized 3:3:3:2 to receive the PDS filled with ranibizumab 10 mg/ml, 40 mg/ml, 100 mg/ml, or monthly intravitreal ranibizumab 0.5-mg injections.Time to first implant refill assessed when the last enrolled patient completed the month 9 visit (primary efficacy end point), improvement in best-corrected visual acuity (BCVA) and central foveal thickness (CFT), and safety.The primary analysis population was 220 patients, with 58, 62, 59, and 41 patients in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. Median time to first implant refill was 8.7, 13.0, and 15.0 months in the PDS 10-mg/ml, PDS 40-mg/ml, and PDS 100-mg/ml arms, respectively. At month 9, the adjusted mean BCVA change from baseline was ‒3.2 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, ‒0.5 ETDRS letters, +5.0 ETDRS letters, and +3.9 ETDRS letters in the PDS 10-mg/ml, PDS 40-mg/ml, PDS 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg arms, respectively. At month 9, the adjusted mean CFT change from baseline was similar in the PDS 100-mg/ml and monthly intravitreal ranibizumab 0.5-mg arms. The optimized PDS implant insertion and refill procedures were generally well tolerated. After surgical procedure optimization, postoperative vitreous hemorrhage rate was 4.5% (7/157; 1 event classified as serious). There was no evidence of implant clogging.In the phase 2 Ladder trial, the PDS was generally well tolerated and demonstrated a dose response across multiple end points in patients with nAMD. The PDS 100-mg/ml arm showed visual and anatomic outcomes comparable with monthly intravitreal ranibizumab 0.5-mg injections but with a reduced total number of ranibizumab treatments. The PDS has the potential to reduce treatment burden in nAMD while maintaining vision.

RG7667, a novel combination of two anticytomegalovirus (anti-CMV) monoclonal IgG1 antibodies (MCMV5322A and MCMV3068A), was designed to block CMV entry into host cells. It was developed as a potential therapy for preventing CMV infection and disease in transplant recipients. RG7667 was assessed for preventing CMV infection in a phase 2a trial with CMV-seronegative recipients of kidney transplants from CMV-seropositive donors. The patients received 4 intravenous doses of RG7667 (10 mg/kg of body weight of each antibody, n = 60) or placebo ( n = 60) at the time of the transplant and at 1, 4, and 8 weeks after the transplant. Serum samples were collected for pharmacokinetic (PK) analysis and antidrug antibody (ADA) evaluation. To guide future dose selection, the relationships between RG7667 exposure and pharmacological activity were evaluated. MCMV5322A and MCMV3068A exposures were confirmed in all RG7667-treated patients. Mean clearances for MCMV5322A and MCMV3068A were 2.97 and 2.65 ml/day/kg, respectively, and the terminal half-lives of MCMV5322A and MCMV3068A were 26.9 and 27.4 days, respectively. The ADA incidence was low and was not associated with lower drug exposure. Patients with RG7667 or component antibody exposures greater than the respective median values had a lower incidence of viremia at 12 weeks and 24 weeks after transplantation and a longer delayed time to detectable CMV viremia than patients with exposures less than the median values. MCMV5322A and MCMV3068A exhibited expected IgG1 PK profiles in high-risk kidney transplant recipients, consistent with the earlier PK behavior of RG7667 in healthy subjects. Higher drug exposure was associated with better anti-CMV pharmacological activity. (This study has been registered at ClinicalTrials.gov under identifier NCT01753167.)

AIMS Sugammadex rapidly reverses moderate and deep rocuronium- or vecuronium-induced neuromuscular blockade at doses of 4 mg/kg and 2 mg/kg, respectively. Sugammadex is renally eliminated. This study evaluated the pharmacokinetics of sugammadex in subjects with renal impairment versus those with normal renal function. METHODS This open-label, two-part, phase 1 study included adults with moderate (creatinine clearance (CLcr) 30

MHAA4549A, a human anti-influenza immunoglobulin (Ig) G1 monoclonal antibody, is being developed to treat patients hospitalized for influenza A infection. This study examined the pharmacokinetics (PKs) of MHAA4549A in a phase IIa, randomized, double-blind, dose-ranging trial in healthy volunteers challenged with influenza A virus. Serum PK data were collected from 60 subjects in three single-dose groups (400, 1200, or 3600 mg) who received MHAA4549A intravenously 24–36 h after inoculation with the influenza A virus. Nasopharyngeal swab MHAA4549A concentration data were collected on days 1–8, and all subjects, including the placebo group, received 75 mg oseltamivir twice daily from days 7 to 11. Plasma samples were collected 4 h postdose on day 8 for oseltamivir and its active metabolite oseltamivir carboxylate (OC) (all subjects, n = 100), including subjects treated with oseltamivir alone and placebo. Noncompartmental analysis was performed for both nasal and serum PKs. MHAA4549A showed dose-proportional serum PKs with a long terminal half-life (approximately 21.9–24.6 days) and slow clearance (approximately 152–240 mL/day); however, nasopharyngeal swab PKs were not dose proportional. No differences in mean plasma concentrations of oseltamivir and OC at 4 h postdose on day 8 were observed between the MHAA4549A treatment and placebo groups. No subjects who received MHAA4549A developed anti-drug antibodies. MHAA4549A serum PKs were consistent with that of a human IgG1antibody without known endogenous targets. MHAA4549A showed nonlinear PKs in nasopharyngeal swab samples, which will guide future dose selection to achieve the high drug concentrations needed at the site of action for efficacy. These data demonstrate no PK interactions between MHAA4549A and oseltamivir, and support flat dosing. ClinicalTrials.gov identifier, NCT01980966.

This study aims at evaluating the utility of the population pharmacokinetics approach in therapeutic protein drug-drug-interaction (DDI) assessment. Simulations were conducted for 2 representative victim drugs, methotrexate and trastuzumab, using a parallel-group design with and without the interaction drug. The effect of a perpetrator on the exposure of the victim drug is described as the ratio of clearance/apparent clearance of the victim drug given with or without the perpetrator. The power of DDI assessment was calculated as the percentage of runs with 90% confidence interval of the estimated DDI effect within 80% to 125% for the scenarios of no DDI, benchmarked with the noncompartmental approach with intensive sampling. The impact of the number of subjects, the number of sampling points per subject, sampling time error, and model misspecification on the power of DDI determination were evaluated. Results showed that with equal numbers of subjects in each arm, the population pharmacokinetics approach with sparse sampling may need about the same or a higher number of subjects compared to a noncompartmental approach in order to achieve similar power. Increasing the number of subjects, even if only in the study drug alone arm, can increase the power. Sampling or dosing time error had notable impacts on the power for methotrexate but not for trastuzumab. Model misspecification had no notable impacts on the power for trastuzumab. Overall, the population pharmacokinetics approach with sparse sampling built in phase 2/3 studies allows appropriate DDI assessment with adequate study design and analysis and can be considered as an alternative to dedicated DDI studies.

Assessment of pharmacokinetic (PK) based drug-drug interactions (DDI) is essential for ensuring patient safety and drug efficacy. With the substantial increase in therapeutic proteins (TP) entering the market and drug development, evaluation of TP-drug interaction (TPDI) has become increasingly important. Unlike for small molecule (e.g., chemical-based) drugs, conducting TPDI studies often presents logistical challenges, while the population PK (PPK) modeling may be a viable approach dealing with the issues. A working group was formed with members from the pharmaceutical industry and the FDA to assess the utility of PPK-based TPDI assessment including study designs, data analysis methods, and implementation strategy. This paper summarizes key issues for consideration as well as a proposed strategy with focuses on (1) PPK approach for exploratory assessment; (2) PPK approach for confirmatory assessment; (3) importance of data quality; (4) implementation strategy; and (5) potential regulatory implications. Advantages and limitations of the approach are also discussed.

Background: Duligotuzumab, a novel dual -action humanized IgG1 antibody that blocks ligand binding to epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3), inhibits signaling from all ligand-dependent HER dimers, and can elicit antibody -dependent cell -mediated cytotoxicity. High tumor -expression of neuregulin 1 (NRG1), a ligand to HER3, may enhance sensitivity to duligotuzumab. Methods: This multicenter, open -label, randomized phase II study (MEHGAN) evaluated drug efficacy in patients with recurrent/metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) progressive on/after chemotherapy and among patients with NRG1 high tumors. Patients received duligotuzumab (1100 mg IV, q2w) or cetuximab (400 mg/m2 load, 250 mg/m2 IV, q1 w) until progression or intolerable toxicity. Tumor samples were assayed for biomarkers [NRG1, ERBB3, and human papillomavirus (HPV) status]. Results: Patients (N =121) were randomized (duligotuzumab:cetuximab; 59:62), median age 62 years; ECOG 0-2. Both arms (duligotuzumab vs. cetuximab, respectively) showed comparable progression -free survival [4.2 vs. 4.0 months; HR: 1.23 (90% confidence interval (Cl): 0.89-1.70)], overall survival [7.2 vs. 8.7 months; HR 1.15 (90% Cl: 0.81-1.63)], and objective response rate (12 vs. 14.5%), with no difference between patients with NRG/ -high tumors or ERBB3-low tumors. Responses in both arms were confined to HPV-negative patients. Grade >3 adverse events (AEs) (duligotuzumab vs. cetuximab, respectively) included infections (22 vs. 11.5%) and GI disorders (17 vs. 7%), contributing to higher rates of serious AEs (41 vs. 29.5%). Metabolic disorders were less frequent with duligotuzumab (10 vs. 16%); any grade rash -related events were less with duligotuzumab (49 vs. 67%). Conclusion: While several lines of preclinical evidence had supported the premise that the blockade of HER3 in addition to that of EGFR may improve outcomes for patients with R/M SCCHN overall or specifically in those patients whose tumors express high levels of NRGI, this study provided definitive clinical evidence refuting this hypothesis. Duligotuzumab did not improve patient outcomes in comparison to cetuximab despite frequent expression of NRG1. These data indicate that inhibition of EGFR alone is sufficient to block EGFR HER3 signaling, suggesting that HER2 plays a minimal role in this disease. Extensive biomarker analyses further show that HPV-negative SCCHN but not HPV-positive SCCHN are most likely to respond to EGFR blockage by cetuximab or duligotuzumab.

Leukotriene B4 (LTB(4)) is a potent inflammatory mediator in asthma, and is increased in more severe asthma. Targeting LTB(4), in addition to cysteinyl leukotrienes, could be beneficial in asthma. This was a randomized, double-blind trial of once-daily MK-0633, a potent 5-lypoxygenase inhibitor, 10 mg, 50 mg, and 100 mg, and placebo in patients 18-70 years with a history of chronic asthma, and FEV(1) ≥45 and ≤85% predicted. There was a 6-week main period and optional 18-week and 34-week periods (52 weeks total), the latter two comparing only MK-0633 100 mg and placebo. The primary endpoint was the change from baseline in FEV(1) over the last 4 weeks of the 6-week primary treatment period. Secondary endpoints included symptom scores, β-agonist use, peak expiratory flow (PEF), asthma quality of life questionnaire (AQLQ), asthma control questionnaire (ACQ), asthma attacks, exacerbations, days with asthma control, post-β-agonist FEV(1), and blood eosinophils. MK-0633 100 mg was significantly more effective than placebo for the change from baseline in FEV(1) (0.20 L vs. 0.13 L; p = 0.004). The other MK-0633 doses were not significantly more effective than placebo. MK-0633 (at various doses) was also more effective than placebo for β-agonist use, AQLQ, AM and PM PEFR, ACQ, and post-β-agonist FEV(1) (p 0.05 for all). MK-0633 was associated with a dose-dependent increase in elevated aspartate aminotransferase and alanine aminotransferase. Because of the relative benefit-risk ratio, the optional study periods were terminated after unblinding for the main study period. Overall, the benefit-risk ratio did not support the clinical utility of MK-0633 in asthma.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Oral contraceptives are a widely prescribed means of birth control that requires the maintenance of adequate pharmacokinetics of the active components to maintain efficacy. • Oral contraceptive use in HIV-infected women is widespread and may often occur in women receiving raltegravir as part of their antiretroviral therapy. • Given the prevalence of oral contraceptive use and likely need for co-administration with raltegravir, combination administration should be studied to assess the safety and the pharmacokinetics of the oral contraceptive components. WHAT THIS STUDY ADDS • This study is the first to provide the practitioner with a detailed description of the influence of raltegravir on the pharmacokinetics of a triphasic oral contraceptive. • This study demonstrates that raltegravir does not meaningfully alter the pharmacokinetics of the estrogen or progestin components of such oral contraceptives. • This paper provides confidence to the practitioner that there will be no clinically meaningful interaction that would preclude the concurrent use of raltegravir and such oral contraceptives in combination. AIMS Oral contraceptives such as norgestimate–ethinyl estradiol (Ortho Tri-Cyclen®) are commonly prescribed in the HIV-infected patient population. A placebo-controlled, randomized, two-period crossover study in healthy HIV-seronegative subjects was conducted to assess the effect of raltegravir on the pharmacokinetics of the estrogen and progestin components of norgestimate–ethinyl estradiol [ethinyl estradiol (EE) and norelgestromin (NGMN), an active metabolite of norgestimate (NGT)]. METHODS In each of two periods, nineteen healthy women established on norgestimate–ethinyl estradiol contraception (21 days of active contraception; 7 days of placebo) received either 400 mg raltegravir or matching placebo twice daily on days 1–21. Pharmacokinetics were analysed on day 21 of each period. RESULTS The geometric mean ratio (GMR) and 90% confidence interval (CI) for the EE component of norgestimate–ethinyl estradiol when co-administrated with raltegravir relative to EE alone was 0.98 (0.93–1.04) for the area under the concentration–time curve from 0 to 24 h (AUC0–24 h) and 1.06 (0.98–1.14) for the maximum concentration of drug in the plasma (Cmax); the GMR (90% CI) for the NGMN component of norgestimate–ethinyl estradiol when co-administered with raltegravir relative to NGMN alone was 1.14 (1.08–1.21) for AUC0–24 h and 1.29 (1.23–1.37) for Cmax. There were no discontinuations due to a study drug-related adverse experience, nor any serious clinical or laboratory adverse experience. CONCLUSIONS Raltegravir has no clinically important effect on EE or NGMN pharmacokinetics. Co-administration of raltegravir and an oral contraceptive containing EE and NGT was generally well tolerated; no dose adjustment is required for oral contraceptives containing EE and NGT when co-administered with raltegravir.

A randomized, placebo-controlled, 2-period crossover study in subjects on methadone maintenance therapy was conducted to assess the effect of the HIV-1 integrase inhibitor, raltegravir, on the pharmacokinetics of methadone. Twelve HIV-negative male and female subjects stabilized on an oral methadone program were enrolled. Subjects maintained their prescribed oral doses of methadone throughout the study and, in each of 2 periods, received either 400 mg of raltegravir or matching placebo every 12 hours on days 1 through 10 of each treatment period with a washout of 7 days between periods. Plasma samples for analysis of methadone pharmacokinetics were collected over 24 hours postdose on day 10 of each treatment period. Safety and tolerability were assessed throughout the study. The geometric mean ratio (90% confidence interval) for methadone when administered with raltegravir relative to methadone alone was 1.00 (0.93-1.09) for area under the methadone concentration time curve from time 0 to 24 hours and 1.00 (0.94-1.07) for maximal concentration. There were no serious clinical or laboratory adverse experiences. There were no discontinuations due to an adverse experience. Coadministration of raltegravir and methadone is generally well tolerated. Raltegravir has no clinically meaningful effect on methadone pharmacokinetics. No dose adjustment is required for methadone when coadministered with raltegravir.

Etravirine, a next-generation nonnucleoside reverse transcriptase inhibitor, and raltegravir, an integrase strand transfer inhibitor, have separately demonstrated potent activity in treatment-experienced, human immunodeficiency virus (HIV)-infected patients. An open-label, sequential, three-period study with healthy, HIV-seronegative subjects was conducted to assess the two-way interaction between etravirine and raltegravir for potential coadministration to HIV-infected patients. In period 1, 19 subjects were administered 400 mg raltegravir every 12 h (q12 h) for 4 days, followed by a 4-day washout; in period 2, subjects were administered 200 mg etravirine q12 h for 8 days; and in period 3, subjects were coadministered 400 mg raltegravir and 200 mg etravirine q12 h for 4 days. There was no washout between periods 2 and 3. Doses were administered with a moderate-fat meal. Etravirine had only modest effects on the pharmacokinetics of raltegravir, while raltegravir had no clinically meaningful effect on the pharmacokinetics of etravirine. For raltegravir coadministered with etravirine relative to raltegravir alone, the geometric mean ratio (GMR) and 90% confidence interval (CI) were 0.90 and 0.68 to 1.18, respectively, for the area under the concentration curve from 0 to 12 h (AUC0-12), 0.89 and 0.68 to 1.15, respectively, for the maximum concentration of drug in serum (Cmax), and 0.66 and 0.34 to 1.26, respectively, for the trough drug concentration (C12); the GMR (90% CI) for etravirine coadministered with raltegravir relative to etravirine alone was 1.10 (1.03, 1.16) for AUC0-12, 1.04 (0.97, 1.12) forCmax, and 1.17 (1.10, 1.26) forC12. All drug-related adverse clinical experiences were mild and generally transient in nature. No grade 3 or 4 adverse experiences or discontinuations due to adverse experiences occurred. Coadministration of etravirine and raltegravir was generally well tolerated; the data suggest that no dose adjustment for either drug is necessary.

Raltegravir is a novel HIV-1 integrase inhibitor with potent in vitro activity (95% inhibitory concentration = 33 nM in 50% human serum). In vitro characterization of raltegravir inhibition potential was assessed against a panel of cytochrome P450 (CYP) enzymes. An open-label, 2-period study was conducted to assess the effect of raltegravir on the pharmacokinetics of midazolam, a sensitive CYP 3A4 probe substrate: period 1, 2.0 mg of midazolam; period 2, 400 mg of raltegravir every 12 hours for 14 days with 2.0 mg of midazolam on day 14. There was no meaningful in vitro effect of raltegravir on inhibition of a panel of CYP enzymes and induction of CYP 3A4. In the presence of raltegravir, midazolam area under the curve extrapolated to infinity (AUC(0-infinity)) and maximum plasma concentration (C(max)) geometric mean ratios were similar (geometric mean ratios and 90% confidence intervals: 0.92 [0.82, 1.03] (P = .208) and 1.03 [0.87, 1.22] (P = .751), respectively). No substantial differences were observed in T(max) (P = .750) or apparent half-life (P = .533) of midazolam. Plasma levels of midazolam were not substantially affected by raltegravir, which implies that raltegravir is not a clinically important inducer or inhibitor of CYP 3A4 and that raltegravir would not be expected to affect the pharmacokinetics of other drugs metabolized by CYP 3A4 to a clinically meaningful extent.

Lampalizumab is an antigen-binding fragment of a humanized monoclonal antibody against complement factor D (CFD), a rate-limiting enzyme in the activation and amplification of the alternative complement pathway (ACP), which is in phase III clinical trials for the treatment of geographic atrophy. Understanding of the pharmacokinetics, pharmacodynamics, and biodistribution of lampalizumab following intravitreal administration in the ocular compartments and systemic circulation is limited but crucial for selecting doses that provide optimal efficacy and safety. Here, we sought to construct a semimechanistic and integrated ocular-systemic pharmacokinetic-pharmacodynamic model of lampalizumab in the cynomolgus monkey to provide a quantitative understanding of the ocular and systemic disposition of lampalizumab and CFD inhibition. The model takes into account target-mediated drug disposition, target turnover, and drug distribution across ocular tissues and systemic circulation. Following intravitreal administration, lampalizumab achieves rapid equilibration across ocular tissues. Lampalizumab ocular elimination is relatively slow, with a τ1/2 of approximately 3 days, whereas systemic elimination is rapid, with a τ1/2 of 0.8 hours. Target-independent linear clearance is predominant in the eye, whereas target-mediated clearance is predominant in the systemic circulation. Systemic CFD synthesis was estimated to be high (7.8 mg/day); however, the amount of CFD entering the eye due to influx from the systemic circulation was small (

Metastasis of circulating tumor cells requires a multistep cascade of events initiated by adhesion of tumor cells to the vascular endothelium of involved tissues. This process occurs under the forces of blood flow and is promoted by adhesion molecules specialized to interact under shear conditions. The endothelial molecule E-selectin is a major mediator of these adhesive events, and there is strong evidence that E-selectin receptor-ligand interactions contribute to the formation of metastasis. However, little is known about the identity of E-selectin ligand(s) expressed on cancer cells. To address this issue, we did SDS-PAGE analysis of membrane proteins, metabolic inhibition studies, and blot rolling assays of LS174T, a colon carcinoma cell line known to interact with E-selectin under physiologic flow conditions. Our studies show that LS174T cells express the hematopoietic cell E/L-selectin (HCELL) glycoform of CD44, which functions as a high-affinity E-selectin glycoprotein ligand on these cells. However, in contrast to the HCELL glycoform on human hematopoietic progenitor cells, which expresses carbohydrate-binding determinant(s) for E-selectin primarily on N-glycans of standard CD44, the relevant determinant(s) on LS174T cells is expressed on O-glycans and is predominantly found on variant isoforms of CD44 (CD44v). Our finding that tumor-associated CD44 splice variant(s) express E-selectin ligand activity provides novel perspectives on the biology of CD44 in cancer metastasis.

Leukocytes are recruited from the bloodstream to sites of inflammation by the selectin family of adhesion receptors. In vivo and in vitro studies reveal distinctive rolling velocities of polymorphonuclear leukocytes over E-, P- and L-selectin substrates. The kinetic and mechanical properties of the selectin-ligand bonds responsible for these differences at the single-molecule level are not well understood. Using single-molecule force spectroscopy, we probe in situ the rupture force, unstressed off-rate and reactive compliance of single selectin receptors to single ligands on whole human polymorphonuclear leukocytes (PMNs) under conditions that preserve the proper orientation and post-translational modifications of the selectin ligands. Single L-selectin bonds to PMNs were more labile than either E- or P-selectin in the presence of an applied force. This outcome, along with a higher unstressed off-rate and a higher reactive compliance, explain the faster L-selectin-mediated rolling. By quantifying binding frequency in the presence of a specific blocking monoclonal antibody or following enzyme treatment, we determined that P-selectin glycoprotein ligand-1 is a high-affinity ligand for E-selectin on PMNs under force. The rupture force spectra and corresponding unstressed off-rate and reactive compliance of selectin-ligand bonds provide mechanistic insights that might help to explain the variable rolling of leukocytes over different selectin substrates.

The initial selectin-dependent events that mediate tumor cell tethering to platelets, leukocytes, and vascular endothelium can regulate the extravasation and colonization of metastatic cells into distant tissues. Little is known, however, about the identity of selectin counter-receptors on tumor cells, which facilitate the metastatic process. To address this issue, we performed SDS-PAGE analysis of membrane proteins, metabolic inhibition studies, blot rolling assays, and cell-free flow-based adhesion experiments using microbeads coated with CD44 immunoprecipitated from carcinomas and purified selectins as substrate. Here, we demonstrate that variant isoforms of CD44 (CD44v) on LS174T colon carcinoma cells possess P-/L-/E-selectin binding activity, in contrast to the standard isoform of CD44 (CD44s) on hematopoietic-progenitor cells (HPCs), which is primarily an L-/E-selectin ligand. Moreover, the selectin-binding determinants on CD44v from LS174T cells are sialofucosylated structures displayed on O-linked glycans, akin to those on P-selectin glycoprotein ligand-1, but distinct from the HECA-452-reactive N-glycans on CD44s expressed on HPCs. Using flow-based adhesion assays, we systematically characterize shear-dependent LS174T CD44 vs. HL60 CD44s adhesion to E-/P-/L-selectin. The novel finding that CD44v are selectin ligands offers a unifying perspective on the apparent enhanced metastatic potential associated with tumor cell CD44v overexpression and the critical role of selectins in metastasis.

Leukocyte recruitment to sites of inflammation is initiated by the selectin family of adhesion receptors. Recent research reveals that P-selectin binding to its ligand exhibits ‘catch’ to ‘slip’ bond transition that may help explain the shear threshold phenomenon.

Purpose: Insulin-like growth factor-1 receptor (IGF-1R) mediates cellular processes in cancer and has been proposed as a therapeutic target. Dalotuzumab (MK-0646) is a humanized IgG1 monoclonal antibody that binds to IGF-1R preventing receptor activation. This study was designed to evaluate the safety and tolerability of dalotuzumab, determine the pharmacokinetic (PK) and pharmacodynamic (PD) profiles, and identify a recommended phase II dose. Experimental Design: Patients with tumors expressing IGF-1R protein were allocated to dose-escalating cohorts of three or more patients each and received intravenous dalotuzumab weekly, every 2 or 3 weeks. Plasma was collected for PK analysis. Paired baseline and on-treatment skin and tumor biopsy samples were collected for PD analyses. Results: Eighty patients with chemotherapy-refractory solid tumors were enrolled. One dose-limiting toxicity was noted, but a maximum-tolerated dose was not identified. Grade 1 to 3 hyperglycemia, responsive to metformin, occurred in 15 (19%) patients. At dose levels or more than 5 mg/kg, dalotuzumab mean terminal half-life was 95 hours or more, mean Cmin was more than 25 μg/mL, clearance was constant, and serum exposures were approximately dose proportional. Decreases in tumor IGF-1R, downstream receptor signaling, and Ki67 expression were observed. 18F-Fluorodeoxy-glucose positron emission tomography metabolic responses occurred in three patients. One patient with Ewing's sarcoma showed a mixed radiologic response. The recommended phase II doses were 10, 20, and 30 mg/kg for the weekly, every other week, and every third week schedules, respectively. Conclusions: Dalotuzumab was generally well-tolerated, exhibited dose-proportional PK, inhibited IGF-1R pathway signaling and cell proliferation in treated tumors, and showed clinical activity. The low clearance rate and long terminal half-life support more extended dosing intervals. Clin Cancer Res; 17(19); 6304–12. ©2011 AACR.

Oral contraceptives such as norgestimate-ethinyl estradiol (Ortho Tri-Cyclen®) are commonly prescribed in the HIV-infected patient population. A placebo-controlled, randomized, two-period crossover study in healthy HIV-seronegative subjects was conducted to assess the effect of raltegravir on the pharmacokinetics of the estrogen and progestin components of norgestimate-ethinyl estradiol [ethinyl estradiol (EE) and norelgestromin (NGMN), an active metabolite of norgestimate (NGT)].In each of two periods, nineteen healthy women established on norgestimate-ethinyl estradiol contraception (21 days of active contraception; 7 days of placebo) received either 400 mg raltegravir or matching placebo twice daily on days 1-21. Pharmacokinetics were analysed on day 21 of each period.The geometric mean ratio (GMR) and 90% confidence interval (CI) for the EE component of norgestimate-ethinyl estradiol when co-administrated with raltegravir relative to EE alone was 0.98 (0.93-1.04) for the area under the concentration-time curve from 0 to 24 h (AUC(0-24 h) ) and 1.06 (0.98-1.14) for the maximum concentration of drug in the plasma (C(max) ); the GMR (90% CI) for the NGMN component of norgestimate-ethinyl estradiol when co-administered with raltegravir relative to NGMN alone was 1.14 (1.08-1.21) for AUC(0-24 h) and 1.29 (1.23-1.37) for C(max) . There were no discontinuations due to a study drug-related adverse experience, nor any serious clinical or laboratory adverse experience.Raltegravir has no clinically important effect on EE or NGMN pharmacokinetics. Co-administration of raltegravir and an oral contraceptive containing EE and NGT was generally well tolerated; no dose adjustment is required for oral contraceptives containing EE and NGT when co-administered with raltegravir.

Summary Chronic obstructive pulmonary disease (COPD) is associated with neutrophil-mediated inflammation, a potential target for treatment in COPD. We evaluated MK-0633, a 5-lipoxygenase inhibitor in patients with COPD. This was a 12 week, randomized, double-blind, multicenter study comparing MK-0633 100 mg and placebo in patients 40–75 years of age ( N = 266) with COPD, post-β-agonist forced expiratory volume in 1 s (FEV 1 ) 25%–75% predicted, and an FEV 1 /forced vital capacity ratio (FVC) ≤70%. Long-acting inhaled bronchodilators were permitted for approximately 50% of patients. The primary efficacy endpoint was the change from baseline in pre-dose (trough) FEV 1 measured over the last 2 weeks of the 12 week treatment period. The change in FEV 1 over the last 2 weeks of the 12 weeks treatment period compared to baseline was 0.015 L for MK-0633 and 0.0002 for placebo ( p = 0.556). For COPD Global Evaluation, 75.4% of patients receiving MK-0633 reported feeling better vs. 59.8% of patients receiving placebo ( p = 0.032). There were no other significant differences between treatments. MK-0633 was well-tolerated and comparable to placebo. The 5-LO inhibitor MK-0633 was not significantly more effective than placebo in improving FEV 1 from baseline in patients with COPD, although more patients reported feeling improved with MK-0633. Clinicaltrials.gov identifier: NCT00418613.

Raltegravir (RAL) is a novel and potent human immunodeficiency virus type 1 integrase inhibitor that is predominantly metabolized via glucuronidation. The protease inhibitor combination tipranavir (TPV) at 500 mg and ritonavir (RTV) at 200 mg (TPV-RTV) has inhibitory and inductive effects on metabolic enzymes, which includes the potential to induce glucuronosyltransferase. Because RAL may be coadministered with TPV-RTV, there is the potential for the induction of RAL metabolism. Consequently, we assessed the effect of TPV-RTV on the pharmacokinetics of RAL and the safety and tolerability of this combination. Eighteen healthy adults were enrolled in this open-label study. The participants received RAL at 400 mg twice daily for 4 days (period 1) and TPV-RTV twice daily for 7 days (period 2), followed immediately by 400 mg RAL with TPV-RTV twice daily for 4 days (period 3). Under steady-state conditions, the RAL concentration at 12 h ( C 12 ) was decreased when RAL was administered with TPV-RTV (geometric mean ratio [GMR], 0.45; 90% confidence interval [CI] 0.31, 0.66; P = 0.0021); however, the area under the concentration-time curve from time zero to 12 h (GMR, 0.76; 90% CI, 0.49, 1.19; P = 0.2997) and the maximum concentration in serum (GMR, 0.82; 90% CI, 0.46, 1.46; P = 0.5506) were not substantially affected. There were no serious adverse experiences or discontinuations due to study drug-related adverse experiences, and RAL coadministered with TPV-RTV was generally well tolerated. Although the RAL C 12 was decreased with TPV-RTV in this study, favorable efficacy data collected in phase III studies substantiate that TPV-RTV may be coadministered with RAL without dose adjustment.

Raltegravir is a human immunodeficiency virus type 1 integrase strand transfer inhibitor with potent activity in vitro and in vivo. Raltegravir is primarily cleared by hepatic metabolism via glucuronidation (via UDP glucuronosyltransferase 1A1), with a minor component of elimination occurring via the renal pathway. Since the potential exists for raltegravir to be administered to patients with hepatic or renal insufficiency, two studies were conducted to evaluate the influence of moderate hepatic insufficiency (assessed by using the Child-Pugh criteria) and severe renal insufficiency (creatinine clearance, 2 ) on the pharmacokinetics of raltegravir. Study I evaluated the pharmacokinetics of 400 mg raltegravir in eight patients with moderate hepatic insufficiency and eight healthy, matched control subjects. Study II evaluated the pharmacokinetics of 400 mg raltegravir in 10 patients with severe renal insufficiency and 10 healthy, matched control subjects. All participants received a single 400-mg dose of raltegravir in the fasted state. In study I, the geometric mean ratios (GMR; mean value for the group with moderate hepatic insufficiency/mean value for the healthy controls) and 90% confidence intervals (CIs) for the area under the concentration-time curve from time zero to infinity (AUC 0-∞ ), the maximum concentration of drug in plasma ( C max ), and the concentration at 12 h ( C 12 ) were 0.86 (90% CI, 0.41, 1.77), 0.63 (90% CI, 0.23, 1.70), and 1.26 (90% CI, 0.65, 2.43), respectively. In study II, the GMRs (mean value for the group with renal insufficiency/mean value for the healthy controls) and 90% CIs for AUC 0-∞ , C max , and C 12 were 0.85 (90% CI, 0.49, 1.49), 0.68 (90% CI, 0.35, 1.32), and 1.28 (90% CI, 0.79, 2.06), respectively. Raltegravir was generally well tolerated by patients with moderate hepatic or severe renal insufficiency, and there was no clinically important effect of moderate hepatic or severe renal insufficiency on the pharmacokinetics of raltegravir. No adjustment in the dose of raltegravir is required for patients with mild or moderate hepatic or renal insufficiency.

Raltegravir, a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, has pH-dependent solubility. Raltegravir plasma concentration increases with omeprazole coadministration in healthy subjects; this is likely secondary to an increase in bioavailability attributable to increased gastric pH. Increased gastric pH has been reported in HIV-1-infected individuals, and the effects of omeprazole in this intended population may be diminished. Further investigation is necessary.

P-selectin expressed on activated platelets and vascular endothelium mediates adhesive interactions to polymorphonuclear leukocytes (PMNs) and colon carcinomas critical to the processes of inflammation and blood-borne metastasis, respectively. How the overall adhesiveness (i.e. the avidity) of receptor/ligand interactions is controlled by the affinity of the individual receptors to single ligands is not well understood. Using single molecule force spectroscopy, we probed in situ both the tensile strength and off-rate of single P-selectin molecules binding to single ligands on intact human PMNs and metastatic colon carcinomas and compared them to the overall avidity of these cells for P-selectin substrates. The use of intact cells rather than purified proteins ensures the proper orientation and preserves post-translational modifications of the P-selectin ligands. The P-selectin/PSGL-1 interaction on PMNs was able to withstand forces up to 175 pN and had an unstressed off-rate of 0.20 s(-1). The tensile strength of P-selectin binding to a novel O-linked, sialylated protease-sensitive ligand on LS174T colon carcinomas approached 125 pN, whereas the unstressed off-rate was 2.78 s(-1). Monte Carlo simulations of receptor/ligand bond rupture under constant loading rate for both P-selectin/PSGL-1 and P-selectin/LS174T ligand binding give distributions and mean rupture forces that are in accord with experimental data. The pronounced differences in the affinity for P-selectin/ligand binding provide a mechanistic basis for the differential abilities of PMNs and carcinomas to roll on P-selectin substrates under blood flow conditions and underline the requirement for single molecule affinity measurements.

3519 Background: IGF1R is a tyrosine kinase receptor that mediates both mitogenic and antiapoptotic pathways and that is expressed in a variety of tumor types. IGF1R activation also mediates resist...