Safety, Reactogenicity, Immunogenicity, and Dose Selection of 10-Valent Extraintestinal Pathogenic Escherichia coli Bioconjugate Vaccine (VAC52416) in Adults Aged 60-85 Years in a Randomized, Multicenter, Interventional, First-in-Human, Phase 1/2a Study

Background

ExPEC10V is a bioconjugate vaccine containing O-antigen polysaccharides of 10 extraintestinal pathogenic Escherichia coli (ExPEC) serotypes. This phase 1/2a study (NCT03819049) assessed the safety, reactogenicity, and immunogenicity of ExPEC10V (VAC52416) to prevent invasive E coli disease in elderly adults.

Methods

The observer-blind, active-controlled design included a 28-day screening, vaccination, 181-day follow-up, and 1-year follow-up. Participants (60-85 years of age) were randomized to ExPEC10V low dose (antigen dose range, 4-8 µg), ExPEC10V medium dose (4-16 µg), or ExPEC10V high dose (8-16 µg); 4-valent ExPEC vaccine (ExPEC4V); or 13-valent pneumococcal conjugate vaccine (PCV13). The incidence of adverse events (AEs; solicited, day 15; unsolicited, day 30; serious AEs, day 181) and immunogenicity (electrochemiluminescent-based assay [ECL] and multiplex opsonophagocytic assay [MOPA]) were assessed. Optimal ExPEC10V dose was determined from safety data through day 30 and an immunogenicity dose selection algorithm based on day 15 ECL and MOPA results.

Results

A total of 416 participants were included (median age, 64.0 years; 54.8% female). The incidences of solicited local and systemic AEs were, respectively, 44.2% and 39.4% for low-dose, 52.9% and 46.1% for medium-dose, 57.7% and 45.2% for high-dose ExPEC10V, and 74.1% and 48.1% for PCV13. Five serious AEs, not vaccine related, were reported. The ECL revealed a robust antibody response to ExPEC10V through year 1. Opsonophagocytic killing activity was detected against all but serotype O8; this lack of response against serotype O8 was linked to low assay sensitivity. Based on the totality of data, high-dose ExPEC10V was considered optimal.

Conclusions

ExPEC10V was well tolerated and immunogenic in elderly adults against all but serotype O8.

120. Safety, Reactogenicity, and Immunogenicity of Three Different Doses of VAC52416 (ExPEC10V) in Adults Aged 60–85 Years in a Randomized, Multicenter, Interventional, First-In-Human, Phase 1/2a Study

Background

This Phase 1/2a study (NCT03819049) assessed the safety, reactogenicity, and immunogenicity of 3 doses of VAC52416 (ExPEC10V), a vaccine candidate to prevent invasive extraintestinal pathogenic Escherichia coli (ExPEC) disease.

Methods

Data from Cohort 1 are described. The observer-blind, active-controlled design included a 28-day screening, vaccination (Day 1), and 181-day follow-up. Participants (60–85 y) were randomized to a single dose of 1 of 5 vaccines (0.5 mL, intramuscular): ExPEC10V-high (n=104), -medium (n=102), or -low (n=104) dose; ExPEC4V (n=52); or pneumococcal 13-valent (PCV13; n=54) (Table 1). Solicited local and systemic adverse events (AEs) until Day 15, unsolicited AEs until Day 30, and serious AEs (SAEs) until Day 181 were assessed. Immunogenicity via electrochemiluminescent (ECL)-based immunoassay and multiplex opsonophagocytic assay (MOPA) was assessed on Day 15. Safety and immunogenicity outcomes were used to select the optimal ExPEC10V dose to be studied in Cohort 2. Table 1.Study Vaccination Dose

EPA, a genetically detoxified form of exotoxin A derived from Pseudomonas aeruginosa; PS, polysaccharide.

ExPEC4V consisted of the O-antigen PSs of the ExPEC serotypes O1A, O2, O6A, and O25B separately bioconjugated to the EPA carrier protein.

ExPEC10V consisted of the O-antigen PSs of the ExPEC serotypes O1A, O2, O4, O6A, O8, O15, O16, O18A, O25B, and O75 separately bioconjugated to the EPA carrier protein.

The EPA (µg) was calculated using a ratio of 0.276 for PS/EPA. However, the final EPA dose was confirmed at the release.

Results

416 participants were included (median age, 64.0 years; 54.8% female). Incidence of solicited AEs was higher in the pooled ExPEC10V groups (local, 160 [51.6%]; systemic, 135 [43.5%]) than with ExPEC4V (local, 15 [28.8%]; systemic, 17 [32.7%]) (Table 2). The high-dose ExPEC10V group experienced a lower or similar incidence of most solicited AEs relative to the PCV13 group (local, 40 [74.1%]; systemic, 26 [48.1%]). A slightly higher incidence of solicited local AEs was reported with the high ExPEC10V dose, relative to low or medium. Five SAEs, not vaccine-related, were reported. An ECL-based immunoassay revealed a robust total IgG antibody response to ExPEC10V against all vaccine serotypes (geometric mean fold increase: low, 2.33–9.54; medium, 2.38–10.05; high, 3.06–12.31). Opsonophagocytic killing activity was demonstrated against all but one serotype (O8). Table 2.Summary of Solicited Adverse Events*Among randomized patients with a vaccine administration documented from the vaccination until Day 15. AE, adverse event.Data are n (%). Participants are counted only once for any given event, regardless of the number of times they actually experienced the event. No Grade 4 solicited AEs were reported.

Conclusion

ExPEC10V is highly immunogenic and well tolerated; no safety issues were identified. High dose ExPEC10V was selected as optimal and will be further characterized in Cohort 2 and long-term follow-up. Because the MOPA lacked sensitivity to detect responses to the O8 serotype, it will be removed from vaccine formulation; ExPEC9V will proceed with clinical development.

Disclosures

Joachim Doua, MD, MPH, Janssen: Employee|Janssen: Stocks/Bonds Michal Sarnecki, MD, Janssen: Employee|Janssen: Stocks/Bonds Bart Spiessens, PhD, Janssen: Employee Oscar Go, PhD, Janssen: Employee of Janssen Research & Development LLC. Todd Davies, PhD, Janssen: Employee of Janssen Research & Development Germie van den Dobbelsteen, PhD, Janssen: Employee of Janssen Vaccines & Prevention B.V.|Janssen: Stocks/Bonds Jan Poolman, PhD, Janssen: Janssen Vaccines & Prevention B.V.|Janssen: Stocks/Bonds Wouter Haazen, MD, MSc, Janssen: Employee of Janssen Research & Development.

Phase 1/2a Safety and Immunogenicity of an Adenovirus 26 Vector Respiratory Syncytial Virus (RSV) Vaccine Encoding Prefusion F in Adults 18-50 Years and RSV-Seropositive Children 12-24 Months

BACKGROUND

Respiratory syncytial virus (RSV) remains a leading cause of pediatric morbidity, with no approved vaccine. We assessed the safety and immunogenicity of the Ad26.RSV.preF vaccine candidate in adults and children.

METHODS

In this randomized, double-blind, phase 1/2a, placebo-controlled study, 12 adults (18-50 years) and 36 RSV-seropositive children (12-24 months) were randomized 2:1 to Ad26.RSV.preF (1 × 1011 viral particles [vp] for adults, 5 × 1010 vp for children) or placebo, at day 1 and 29, with 6-month immunogenicity and 1-year safety follow-up. Respiratory syncytial virus infection was an exploratory outcome in children.

RESULTS

In adults, solicited adverse events (AEs) were generally mild to moderate, with no serious AEs. In children, no vaccination-related serious AEs were reported; fever was reported in 14 (58.3%) Ad26.RSV.preF recipients. Baseline pediatric geometric mean titers for RSV A2 neutralization increased from 121 (95% confidence interval [CI], 76-191) to 1608 (95% CI, 730-3544) at day 29, and 2235 (95% CI, 1586-3150) at day 57, remaining elevated over 7 months. Respiratory syncytial virus infection was confirmed in fewer children receiving Ad26.RSV.preF (1, 4.2%) than placebo (5, 41.7%).

CONCLUSIONS

Ad26.RSV.preF demonstrated immunogenicity in healthy adults and toddlers, with no safety concerns raised. Evaluations in RSV-seronegative children are underway.

Prevention of Respiratory Syncytial Virus Infection in Healthy Adults by a Single Immunization of Ad26.RSV.preF in a Human Challenge Study

BACKGROUND

Respiratory syncytial virus (RSV) is a significant cause of severe lower respiratory tract disease in children and older adults, but has no approved vaccine. This study assessed the potential of Ad26.RSV.preF to protect against RSV infection and disease in an RSV human challenge model.

METHODS

In this double-blind, placebo-controlled study, healthy adults aged 18-50 years were randomized 1:1 to receive 1x1011 vp Ad26.RSV.preF or placebo intramuscularly. Twenty-eight days post-immunization, volunteers were challenged intranasally with RSV-A (Memphis 37b). Assesments included viral load (VL), RSV infections, clinical symptom score (CSS), safety and immunogenicity.

RESULTS

Post-challenge, VL, RSV infections and disease severity were lower in Ad26.RSV.preF (n=27) versus placebo (n=26) recipients: median VL-AUC (area under the curve) qRT-PCR: 0.0 versus 236.0 (P=.012; predefined primary endpoint); median VL-AUC quantitative culture: 0.0 versus 109; RSV infections 11 (40.7%) versus 17 (65.4%); median RSV AUC-CSS 35 versus 167, respectively. From baseline to 28 days post-immunization, geometric mean fold-increases in RSV A2 neutralizing antibody titers of 5.8 and 0.9 were observed in Ad26.RSV.preF and placebo, respectively. Ad26.RSV.preF was well tolerated.

CONCLUSIONS

Ad26.RSV.preF demonstrated protection from RSV infection through immunization in a human challenge model, and therefore could potentially protect against natural RSV infection and disease.

CLINICAL TRIALS REGISTRATION

NCT03334695.

Safety and Immunogenicity of the Ad26.RSV.preF Investigational Vaccine Coadministered With an Influenza Vaccine in Older Adults

Background

Respiratory syncytial virus (RSV) and influenza cause significant disease burden in older adults. Overlapping RSV and influenza seasonality presents the opportunity to coadminister vaccines for both infections. This study assessed coadministration of the investigational vaccine, Ad26.RSV.preF, an adenovirus serotype 26 (Ad26) vector encoding RSV F protein stabilized in its prefusion conformation (pre-F), with a seasonal influenza vaccine in older adults.

Methods

In this phase 2a, double-blind, placebo-controlled study, 180 adults aged ≥60 years received Ad26.RSV.preF plus Fluarix on day 1 and placebo on day 29, or placebo plus Fluarix on day 1 and Ad26.RSV.preF on day 29 (control).

Results

The coadministration regimen had an acceptable tolerability profile. Reactogenicity was generally higher after Ad26.RSV.preF versus Fluarix, but symptoms were generally transient and mild or moderate. At 28 days after the first vaccination, the upper confidence intervals of the hemagglutination inhibition antibody geometric mean ratio (control/coadministration) for all influenza strains were <2, demonstrating noninferiority. Robust neutralizing and binding antibody responses to RSV A2 were observed in both groups.

Conclusions

Coadministration of Fluarix with Ad26.RSV.preF vaccine had an acceptable safety profile and showed no evidence of interference in immune response. The results are compatible with simultaneous seasonal vaccination with both vaccines.

Clinical Trials Registration

NCT03339713.

902. A Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy of a Single Immunization of Ad26.RSV.preF against RSV Infection in a Viral Challenge Model in Healthy Adults

Background

Despite the high disease burden of RSV in older adults and children, there is currently no approved vaccine. Ad26.RSV.preF, an experimental RSV vaccine, has demonstrated immunogenicity and tolerability in first-in-human clinical studies. The aim of this study was to assess the potential of the Ad26.RSV.preF vaccine to protect against RSV infection and disease in an established RSV human challenge model, used for the first time to evaluate a vaccine.

Methods

We conducted a randomized, double-blind, placebo-controlled, human challenge study (NCT03334695). Healthy adults received 1 × 1011 vp Ad26.RSV.preF vaccine (active) or placebo (pbo) intramuscularly. After 28 days, volunteers were challenged intranasally with a low-passage clinical strain of RSV-A (0.8 mL of Memphis 37b) and then quarantined for 12 days. Nasal washes were collected twice daily throughout quarantine, starting 2 days post-challenge (viral load [VL] by qRT-PCR and quantitative cultures). Disease severity was recorded thrice daily using symptom diary cards.

Results

Fifty-three volunteers (active, n = 27; pbo, n = 26) were challenged with RSV-A. Quantitative viral assessments were consistently lower in active than pbo. The primary endpoint of the study was met: the area under the curve (AUC) for RSV VL over time (via qRT-PCR) was significantly lower in active pbo (P = 0.012). Median peak VL was lower for active (0 log10 copies/mL) than pbo (5.4 log10 copies/mL). Median AUC for RSV VL over time (quantitative culture) was lower for active than pbo (0 vs. 109, P = 0.002). Disease severity was lower for active than pbo, with a median AUC total symptom score of 35 (active) vs. 167 (pbo) (P = 0.002). Overall, RSV infection (defined by qRT-PCR alone or combined with symptoms) and disease severity over time were lower in active vs. pbo.

Conclusion

RSV infections, VL, and RSV disease severity were consistently lower in healthy adults receiving Ad26.RSV.preF vs. placebo, demonstrating promising protection from RSV infection and disease. This was the first time that antiviral prevention was observed against RSV after active immunization. Ad26.RSV.preF warrants further evaluation in field trials for efficacy against natural RSV infections in populations considered at risk of severe RSV disease.

Disclosures

All Authors: No reported Disclosures.

2775. Safety and Immunogenicity of a Seasonal Influenza Vaccine and Ad26.RSV.preF Vaccine With and Without Co-Administration: A Randomized, Double-Blind, Placebo-Controlled Phase 2a Study in Adults Aged ≥ 60 Years

Background

Influenza and RSV can cause respiratory tract infections leading to severe illness, hospitalization and mortality in at-risk populations, particularly the elderly. The seasonality of influenza and RSV present the potential to co-administer vaccines. This study aimed to demonstrate the non-inferiority of co-administration of the experimental RSV vaccine Ad26.RSV.preF with an influenza vaccine (Fluarix) vs. Fluarix alone in terms of immunogenicity against influenza.

Methods

This was a single-center, randomized, double-blind, placebo-controlled Phase 2a study (NCT03339713) in healthy adults ≥60 years old. Volunteers were randomized 1:1 to receive Fluarix + 1 × 1011 vp Ad26.RSV.preF on Day 1 and placebo on Day 29 (Group 1), or Fluarix + placebo on Day 1 and 1 × 1011 vp Ad26.RSV.preF on Day 29 (Group 2). Blood samples were taken prior to each vaccination and at Day 57. The primary endpoints were geometric mean titers (GMTs) of hemagglutination inhibition (HI) antibody titers against Fluarix strains (A/Michigan, A/Hong Kong, B/Brisbane and B/Phuket) and the safety and tolerability of Ad26.RSV.preF administered with or without Fluarix. A key secondary endpoint was neutralizing antibody titers to RSV A2.

Results

Volunteers (N = 180) were included in Group 1 (n = 90) or Group 2 (n = 90). Most volunteers were white (89%) and female (63%), with a median age of 65 years. Both groups exhibited an increase from baseline in HI antibody response on Day 29. The 95% one-sided upper confidence limit of all GMT ratios were below the non-inferiority margin of 2. The frequency of solicited adverse events (AE) after Ad26.RSV.preF vaccination was similar with and without influenza co-administration. Solicited AEs were mainly of Grade 1 and 2 and of transient duration. Most unsolicited AEs were considered unrelated to the study vaccination and were Grade 1 or 2. There were no serious AEs related to the study vaccine and there were no discontinuations due to AEs. RSV neutralizing antibody titers 29 days post- Ad26.RSV.preF immunization were similar in both groups (1404, Group 1; 1690, Group 2).

Conclusion

Co-administration of Ad26.RSV.preF with Fluarix was non-inferior to Fluarix alone in terms of immunogenicity against influenza and had an acceptable tolerability profile.

Disclosures

All authors: No reported disclosures.

2712. Safety and Immunogenicity of two Doses of ExPEC4V Vaccine Against Extraintestinal Pathogenic Escherichia coli Disease in Healthy Adult Participants

Background

The ExPEC4V vaccine contains 4 Escherichia coli O-antigens (O1A, O2, O6A, O25B) conjugated to exotoxin protein A and is being studied for prevention of Invasive Extraintestinal pathogenic E. coli (ExPEC) Disease (IED). This phase-2 double-blind study assessed safety and immunogenicity of ExPEC4V Clinical Trial Material (CTM), manufactured via a redesigned process (optimized O1A strain).

Methods

Participants (≥18 years) in stable health were randomized (3:1) to receive ExPEC4V dose 4:4:4:8 μg PS/serotype or placebo on Day 1 and second vaccination on Day 181 (6 months after first vaccination). Participants will be followed for safety until end of study at Day 360. Reactogenicity and immunogenicity (by ELISA, opsonophagocytic killing [OPA] assays) were evaluated pre-vaccination, and 15 days after first and second vaccinations (Day 195).

Results

Of 100 participants randomized (mean age 56, 48% males) and vaccinated (ExPEC4V, n = 75; placebo, n = 25), 97 completed Day 30. Solicited local AEs were higher for ExPEC4V (38.7%) than placebo (20%); most frequent was pain/tenderness (38.7% vs 20%). Solicited systemic AEs were higher in ExPEC4V (49.3%) than placebo (20%); most frequent was fatigue (32% vs. 12%). No serious or grade 3 solicited local AEs were reported. One participant in ExPEC4V experienced a grade 3 solicited systemic fatigue considered vaccine-related by investigator. ExPEC4V demonstrated immune responses against all serotypes at Day 15. Geometric mean titer effective concentration rank by serotypes was O2 > O1A > O6 > O25B (Figures 1 and 2). At Day 15, ≥ 82% of participants in ExPEC4V and none in placebo had ≥2-fold increase from baseline of ELISA titer for all serotypes. In ExPEC4V, ≥47% had ≥2-fold increase from baseline of OPA titer for all serotypes, while 8% in placebo had ≥2-fold increase only for O6A. Good correlation was observed between ELISA and OPA across serotypes (r ≥ 0.76).

Conclusion

ExPEC4V elicited robust and functional immune responses across all serotypes and was well tolerated with no vaccine safety findings. This study supports the development of future multivalent ExPEC vaccine to prevent IED.

Disclosures

All authors: No reported disclosures.

Safety and immunogenicity of a vaccine for extra-intestinal pathogenic Escherichia coli (ESTELLA): a phase 2 randomised controlled trial

BACKGROUND

ExPEC4V (JNJ-63871860) is a bioconjugate vaccine, containing O-antigens from Escherichia coli serotypes O1A, O2, O6A, and O25B, developed for the prevention of invasive extra-intestinal pathogenic E coli (ExPEC) disease. We aimed to assess safety, reactogenicity, and immunogenicity of ExPEC4V in healthy adults.

METHODS

In this phase 2 randomised, double-blind placebo-controlled study, we recruited healthy adults (≥18 years with a body-mass index of 35 kg/m² or less) between Nov 16, 2015, and Aug 8, 2017, and randomly assigned them to receive a single dose of ExPEC4V (antigen O1A:O2:O6A:O25B content 4:4:4:4 μg [group 1]; 4:4:4:8 μg [group 2], 8:8:8:8 μg [group 3], 8:8:8:16 μg [group 4], or 16:16:16:16 μg [group 5]) or placebo. The primary objectives were evaluation of the safety, tolerability, and immunogenicity of ExPEC4V and determination of its dose-dependent immunogenicity 15 days after vaccination by ELISA in individuals who had received at least one vaccination dose. Antibody titres and safety evaluation were used to select two ExPEC4V doses for assessment up to day 360. This trial is registered at ClinicalTrials.gov, number NCT02546960.

FINDINGS

Of 848 enrolled participants, 843 (99%) received the ExPEC4V vaccine (757) or placebo (86) and were included in the safety analysis. Of 757 participants vaccinated with ExPEC4V, 222 (29%) had a solicited local adverse event and 325 (43%) had any solicited systemic adverse event, compared with 11 (13%) and 30 (35%) of 86 participants in the control group. Symptoms were mild-to-moderate. The most frequently reported solicited local adverse event was pain or tenderness (205 [27·1%] of 757 in combined ExPEC4V groups) and the most frequently reported solicited systemic adverse event was fatigue (208 [27·6%] of 757). Only 13 (2%) of 843 had a grade 3 event. At day 15, 80% or more of all participants achieved a two times or greater increase in serotype-specific IgG antibodies (except O25B at the lowest dose, 103 [72%] of 144). At day 360, 66% (95% CI 56·47-74·33) of participants in group 2 and 71% (62·13-78·95) of participants in group 4 selected for long-term follow-up maintained a two times or greater increase in serotype-specific antibody compared with baseline.

INTERPRETATION

EXPEC4V seemed well tolerated and elicited robust and functional antibody responses across all serotypes, doses, and age groups. For the two dosages evaluated (4:4:4:8 μg and 8:8:8:16 μg), the immune response persisted for 1 year.

FUNDING

Janssen Pharmaceuticals.

Evaluation of the immunogenicity of the dabigatran reversal agent idarucizumab during Phase I studies

Aims

Idarucizumab, a humanized monoclonal anti‐dabigatran antibody fragment, is effective in emergency reversal of dabigatran anticoagulation. Pre‐existing and treatment‐emergent anti‐idarucizumab antibodies (antidrug antibodies; ADA) may affect the safety and efficacy of idarucizumab. This analysis characterized the pre‐existing and treatment‐emergent ADA and assessed their impact on the pharmacokinetics and pharmacodynamics (PK/PD) of idarucizumab.

Methods

Data were pooled from three Phase I, randomized, double‐blind idarucizumab studies in healthy Caucasian subjects; elderly, renally impaired subjects; and healthy Japanese subjects. In plasma sampled before and after idarucizumab dosing, ADA were detected and titrated using a validated electrochemiluminescence method. ADA epitope specificities were examined using idarucizumab and two structurally related molecules. Idarucizumab PK/PD data were compared for subjects with and without pre‐existing ADA.

Results

Pre‐existing ADA were found in 33 out of 283 individuals (11.7%), seven of whom had intermittent ADA. Titres of pre‐existing and treatment‐emergent ADA were low, estimated equivalent to <0.3% of circulating idarucizumab after a 5 g dose. Pre‐existing ADA had no impact on dose‐normalized idarucizumab maximum plasma levels and exposure and, although data were limited, no impact on the reversal of dabigatran‐induced anticoagulation by idarucizumab. Treatment‐emergent ADA were detected in 20 individuals (19 out of 224 treated [8.5%]; 1 out of 59 received placebo [1.7%]) and were transient in ten. The majority had specificity primarily toward the C‐terminus of idarucizumab. There were no adverse events indicative of immunogenic reactions.

Conclusion

Pre‐existing and treatment‐emergent ADA were present at extremely low levels relative to the idarucizumab dosage under evaluation. The PK/PD of idarucizumab appeared to be unaffected by the presence of pre‐existing ADA.

Pharmacokinetics and Pharmacodynamics of Omarigliptin, a Once-Weekly Dipeptidyl Peptidase-4 (DPP-4) Inhibitor, After Single and Multiple Doses in Healthy Subjects

The pharmacokinetics (PK) and pharmacodynamics (PD) of omarigliptin, a novel once-weekly DPP-4 inhibitor, were assessed following single and multiple doses in healthy subjects. Absorption was rapid, and food did not influence single-dose PK. Accumulation was minimal, and steady state was reached after 2 to 3 weeks. Weekly (area under the curve) AUC and C_max displayed dose proportionality within the dose range studied at steady state. The average renal clearance of omarigliptin was ∼2 L/h. DPP-4 inhibition ranged from ∼77% to 89% at 168 hours following the last of 3 once-weekly doses over the dose range studied. Omarigliptin resulted in ∼2-fold increases in weighted average postprandial active GLP-1. Omarigliptin acts by stabilizing active GLP-1, which is consistent with its mechanism of action as a DPP-4 inhibitor. Administration of omarigliptin was generally well tolerated in healthy subjects, and both the PK and PD profiles support once-weekly dosing. A model-based assessment of QTc interval risk from the single ascending dose study predicted a low risk of QTc prolongation within the likely clinical dose range, a finding later confirmed in a thorough QT trial.

Multiple-Dose Administration of Sitagliptin, a Dipeptidyl Peptidase-4 Inhibitor, Does Not Alter the Single-Dose Pharmacokinetics of Rosiglitazone in Healthy Subjects

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is an incretin enhancer that is approved for the treatment of type 2 diabetes. Sitagliptin is mainly renally eliminated and not a potent inhibitor of CYP450 enzymes in vitro. Rosiglitazone, a thiazolidenedione, is an insulin sensitizer and mainly metabolized by CYP2C8. Since both agents may potentially be coadministered, the purpose of this study was to examine the effects of sitagliptin on rosiglitazone pharmacokinetics. In this open-label, randomized, 2-period, crossover study, 12 healthy normoglycemic subjects, 21 to 44 years, received single 4-mg doses of rosiglitazone alone in one period and coadministered with sitagliptin on day 5 following a multiple-dose regimen for sitagliptin (200 mg once daily x 5 days) in the other period. The geometric mean ratios and 90% confidence intervals ([rosiglitazone + sitagliptin]/rosiglitazone) for rosiglitazone AUC(0-infinity) and Cmax were 0.98 (0.93, 1.02) and 0.99 (0.88, 1.12), respectively. In conclusion, sitagliptin did not alter the pharmacokinetics of rosiglitazone in healthy subjects.