Tolerability and pharmacokinetics of TB-402 in healthy male volunteers

Clinical Therapeutics/Volume 32, Number 6, 2010

Tolerability and Pharmacokinetics of TB-402 in Healthy Male Volunteers Peter Verhamme, MD, PhD1; Steve Pakola, MD2; Thomas J. Jensen, MD, PhD3; Kristina Berggren, PhD4; Elisabeth Sonesson, PhD4; Jean-Marie Saint-Remy, MD, PhD1; Torben Balchen, MSc5; Ann Belmans, MSc6; Geraldine Cahillane, BA2; Jean-Marie Stassen, PhD2; Kathelijne Peerlinck, MD, PhD1; Steven Glazer, MD4; and Marc Jacquemin, MD, PhD1 1Center

for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium; 2ThromboGenics NV, Leuven, Belgium; 3Cyncron Clinical Research Unit, Copenhagen, Denmark; 4BioInvent International AB, Lund, Sweden; 5TrialUnit, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark; and 6Leuven Biostatistics and Statistical Bioinformatics Centre, Leuven, Belgium ABSTRACT Background: TB-402, a human monoclonal antibody that partially inhibits Factor VIII activity (FVIII:C), is being developed as a long-acting antithrombotic agent. Objectives: The primary goal of this study was to investigate the tolerability of TB-402 in healthy male volunteers. Secondary objectives were to determine the pharmacokinetics and pharmacodynamics of TB-402. Methods: In this ascending-dose study, healthy subjects aged 18 to 45 years were randomly assigned in a 2:1 ratio to receive TB-402 administered as a single intravenous bolus at 0.015, 0.1, 0.5, 2.5, 12.5, 37.5, 188, 620, or 1860 μg/kg or matching inactive vehicle (placebo). An older group (55–75 years) was also administered the highest dose that was well tolerated in the younger group (1860 μg/kg). Adverse events (AEs) were obtained from spontaneous reporting and from answers to nonleading questions asked by the principal investigator and study staff during follow-up visits on days 4, 7 (±1 day), 14 (±1 day), 21 (±2 days), 28 (±3 days), 42 (±3 days), and 56 (±3 days) after TB-402 administration. AEs were monitored up to the last study visit on day 56 after the administration of TB-402 or placebo, with special attention to bleeding events. The pharmacodynamic assessment of TB-402 included changes in FVIII:C, activated partial thromboplastin time (APTT), and prothrombin time (PT). Results: The study enrolled 56 subjects (mean ages: younger group, 28 years [range, 20–45 years]; older group, 65 years [range, 58–76 years]; weight, 79 kg [range, 60–104 kg] and 81 kg [range, 64–94 kg], reJune 2010

spectively). Thirty-one of the 38 subjects who received TB-402 (82%) experienced a total of 85 treatmentemergent AEs (TEAEs), and 14 of 18 subjects who received placebo (78%) experienced 35 TEAEs. A total of 34 bleeding events were reported in 13 of 38 subjects (34%) who received TB-402 and 7 of 18 subjects (39%) who received placebo. Most common AEs reported in subjects who received TB-402 were headache (11 [29%]), vessel puncture-site hematoma (7 [18%]), and traumatic hematoma (5 [13%]); with placebo, these AEs were vessel puncture-site hematoma (4 [22%]), headache (3 [17%]), vasovagal reaction (3 [17%]), and hematuria (3 [17%]). No serious AEs considered to be related to TB-402 were reported, and no dose-dependent increases in bleeding events were observed. On pharmacokinetic analysis of TB-402, the t1/2 values across doses were 22.9 days (age 18–45 years) and 19.5 days (age 55–75 years). TB-402 was associated with a reduction in FVIII:C over a period of ~48 hours in the ≥37.5-μg/kg dose groups. TB-402 was associated with a prolonged APTT at doses ≥2.5 μg/kg (~1.1– 1.2-fold predose APTT). Administration of a higher dose of TB-402 was associated with an extended duration of APTT prolongation. No significant effect on PT was found. Conclusions: In this study in healthy male volunteers, TB-402 was well tolerated in the population studied. Accepted for publication April 22, 2010. doi:10.1016/j.clinthera.2010.06.012 0149-2918/$ - see front matter © 2010 Excerpta Medica Inc. All rights reserved.

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Clinical Therapeutics Based on the findings from this study, the long t1/2 of TB-402 may allow a pharmacodynamic effect over a prolonged period after single-dose administration. Further trials are needed to address the tolerability and efficacy of this agent in preventing thromboembolism. Clinicaltrials.gov identifier: NCT00612196. (Clin Ther. 2010;32:1205–1220) © 2010 Excerpta Medica Inc. Key words: Factor VIII, TB-402, antithrombotic, long-acting anticoagulant.

INTRODUCTION Achieving an optimal balance between efficacy (thrombosis prevention) and tolerability (bleeding complications) is a major objective in the development of antithrombotic agents. Most anticoagulant drugs developed to date or currently in development have a dose-dependent activity.1 A dose that is too high may lead to impaired function of the coagulation system and may cause bleeding, whereas a dose that is too low may be ineffective in preventing thrombosis. To minimize the risks for underdosing or overdosing, drugs are being developed that only partially inhibit the activity of the target coagulation factor(s) irrespective of the excess of the drug. These drugs might overcome the dose-dependent efficacy and tolerability issues of antithrombotic agents. In some patients, an immune response to coagulation factors develops, and antibodies are produced that only partially inhibit the target coagulation factor. The immune response in patients with hemophilia A in whom a partial inhibitor of Factor VIII (FVIII) developed has been the focus of some studies. This research has allowed for the development of TB-402 (previously, mAbLE2E9Q), a human monoclonal antibody that only partially inhibits FVIII activity (FVIII:C). TB-402 is a fully human immunoglobulin (Ig) G4 antibody and has been found to inhibit 40% to 70% of FVIII:C in in vitro assays even in the presence of excess antibody.2 Due to the long t1/2 of IgG4 antibodies,3 the low concentration of FVIII in plasma, and the partial FVIII:C inhibition, it has been hypothesized that TB-402 might offer longacting and stable thromboprophylaxis in patients at high risk for thrombosis. Based on the findings from a literature search, the anticoagulant potential of a FVIII inhibitor has not been explored to date.1 The reason for this might be the bleeding complications that occur in patients with hemophilia A who lack FVIII:C completely (severe hemophilia) or to a large extent (moderate hemophilia). 1206

However, patients with mild hemophilia A (6%– 49% FVIII:C) do not experience spontaneous bleeding and lead a normal life.4 Venous thrombosis is rare in patients with mild hemophilia A.5 Epidemiologic studies have reported that high FVIII:C values represent an important risk factor for thrombosis.6,7 A decreased rate of mortality related to ischemic heart disease was observed among carriers of hemophilia.8 These observations support a clinically important role for FVIII in venous and arterial thrombosis. TB-402 has been reported to reduce thrombus formation in animal models of thrombosis. In a mouse model of a mutation in the heparin binding site of antithrombin and spontaneous chronic thrombosis at several sites, TB-402 administration was associated with significant inhibition of thrombotic priapism development in all of the mice tested.9 TB-402 was also associated with significantly reduced thrombus development in a male baboon arteriovenous shunt thrombosis model.10 In the animal models tested, TB-402 did not lead to exaggerated bleeding. The primary goal of this study was to investigate the tolerability of TB-402 in healthy male volunteers. Secondary objectives were to determine the pharmacokinetics and pharmacodynamics of TB-402.

SUBJECTS AND METHODS The protocol and amendments were approved by the Ethics Committees for Copenhagen and Frederiksberg Municipalities and the Danish Medicines Agency. Written informed consent was obtained before any studyrelated procedures were performed. The study was performed in compliance with the principles of the Declaration of Helsinki.11

Inclusion and Exclusion Criteria Healthy male subjects were selected from a panel of volunteers recruited at the Cyncron Clinical Research Unit, Copenhagen, Denmark. Subjects were screened for inclusion in the study within 21 days before study drug administration. Volunteers were included if they were male; were aged 18 to 45 years or 55 to 75 years of age; had no clinically important findings on physical examination, screening laboratory analysis, or ECG; had a body weight between 50 and 100 kg and a body mass index between 18 and 30 kg/m2; were able to communicate well with the investigator and to comply with the requirements of the entire study; were nonsmokers; and had negative fecal occult blood. Volume 32 Number 6

P. Verhamme et al. Volunteers were excluded if they had any autoimmune or allergic disease; had a history of a serious adverse reaction or serious hypersensitivity to any drug; had a history of an allergic reaction to Ig; had received any vaccination within 30 days before the start of the study; had consumed aspirin, other NSAIDs, or other drugs that might affect platelet function or any other aspect of coagulation within 14 days before the start of the study; had abnormal platelet function on study day 1, as determined using platelet aggregation; had a history of important bleeding episodes, personal or family history of coagulation or bleeding disorders, or reasonable suspicion of vascular malformations; had significant trauma or surgery within 12 weeks before screening; had a history of a significant gastrointestinal disorder; had cancer within 10 years before the study (with the exception of adequately managed basal cell carcinoma or testicular carcinoma Stage I); had clinically significant abnormal values on any coagulation test; had screening FVIII:C <50%; had received any investigational medicinal product within 30 days before entry into the study; had previously participated in a TB-402 study; had used any prescribed medication within 14 days or over-thecounter medication within 5 days of study drug administration (with the exception of those deemed by the investigator not to interfere with the outcome of the study); had any major illness within 30 days before screening; had current or a history of any significant disease; had any surgical or medical condition that, in the opinion of the investigator, might interfere with the distribution, metabolism, or excretion of the investigational medicinal product; had a history of any drug or alcohol abuse in the 2 years before the start of the study; had undergone the donation or loss of >500 mL of blood within 12 weeks before entry into the study; and/or had hepatitis B surface antigen, hepatitis C antibody, and/or HIV-1 or -2 antibodies at screening.

Study Design In this ascending-dose, double-blind, placebocontrolled study, subjects were randomly assigned, in a 2:1 ratio using a computer-generated randomization list, to receive TB-402 0.015, 0.1, 0.5, 2.5, 12.5, 37.5, 188, 620, or 1860 μg/kg body weight or matching inactive vehicle (placebo), administered as a single intravenous bolus over a period of 60 minutes. The 0.015-dose group had 4 planned subjects (2 active, 2 placebo), and all of the other dose groups had 6 planned subjects (4 active, 2 placebo). For the purpose of observing the June 2010

tolerability of each dose, study drug administration was started after an interval of ≥2 weeks after the start of administration of the previous dose. Administration of each successive dose proceeded only if no tolerability findings suggested an undue risk to subjects exposed to higher doses. The conservative starting dose of 0.015 μg/ kg was selected by applying a safety factor of 10 to the Minimum Anticipated Biological Effect Level.12 The randomization schedule was held by the Cyncron Quality Management Department and by the Cyncron pharmacy, where it was required for unit-dose preparation purposes. No other study personnel had access to the randomization data until database lock. On entry into the study, a subject was given the next available subject number, and the corresponding dosage was obtained from the pharmacy. Subjects in the older group were to be administered the highest dose considered well tolerated in the younger group.

Study Drug Administration TB-402 (lot no. TF101; expiration, December 2007) was manufactured as an intravenous solution in accordance with Good Manufacturing Practice guideline13 by BioInvent International AB, Lund, Sweden, and the finished drug product was manufactured by Nova Laboratories Ltd., Leicester, United Kingdom. The buffer solution for the dilution of TB-402 was manufactured by Apoteket AB, Stockholm, Sweden, and also served as the matching placebo.

Tolerability Adverse events (AEs) were obtained from spontaneous reporting and from answers to nonleading questions asked by the principal investigator and study staff during follow-up visits on days 4, 7 (±1 day), 14 (±1 day), 21 (±2 days), 28 (±3 days), 42 (±3 days), and 56 (±3 days) after TB-402 administration. AEs were assessed with respect to severity, duration, and relationship to the trial drug, with special attention to bleeding events. AEs included changes from baseline in physical examination findings, including vital sign measurements, ECG, and laboratory test results (hematology, clinical chemistry, urinalysis, and TB-402 antibodies), all conducted by blinded evaluators. Medical history and AEs were coded using the Medical Dictionary for Regulatory Activities14 organ classes and preferred terms, and concurrent use of medications was coded using the WHO’s Drug Dictionary Enhanced.15 1207

Clinical Therapeutics Hematology, clinical chemistry, and urinalysis were conducted at screening and on days –1 (admission), 1, 2, 4, and 56 after the start of the administration of the study drug. Analyses were carried out by a central accredited laboratory (Clinical Chemical Department, University Hospital, Gentofte, Denmark). Hematology tests included red and white blood cell counts and differentials (ADVIA 2120 hematology system, Bayer Diagnostics, Tarrytown, New York). Clinical chemistry tests included aspartate and alanine aminotransferases, albumin, calcium, potassium, sodium, cholesterol, triglycerides, alkaline phosphatase, γ-glutamyl transpeptidase, glucose, phosphate, urea, creatinine, total bilirubin, and total protein (Vitros 950, Ortho-Clinical Diagnostics, Johnson & Johnson AB, Sollentuna, Sweden).

Immunogenicity TB-402 antibodies were analyzed before study drug administration (baseline) and at 28, 42, and 56 days after the start of the IV infusion with an ELISA screening assay that used immobilized TB-402 as catcher and biotin-labeled TB-402 as detector (Charles River Laboratories, Edinburgh, Scotland). An anti-idiotypic antibody was used as a positive control.

Pharmacokinetic Assessment All subjects who received TB-402 were included in the pharmacokinetic analyses. The TB-402 concentration was measured in a competitive assay in which the binding of biotinylated FVIII to immobilized TB-402 was inhibited by TB-402 present in the test sample (Charles River Laboratories).10 The lower limit of quantitation (LLOQ) was 1 μg/mL. Samples for pharmacokinetic assessments were collected immediately before (baseline) and at 0.5, 1, 1.5, 2, 5, 12, 24, and 48 hours, and 4, 7, 14, 21, 28, 42, and 56 days after the start of study drug administration. Primary pharmacokinetic variables included Cmax, Tmax, AUC0–∞, elimination t1/2, total body clearance (CL), and apparent volume of distribution at steady state (Vss).

Coagulation Parameters Coagulation parameters were analyzed using the STA-R Evolution coagulation analyzer (Diagnostica Stago, Parsippany, New Jersey). FVIII:C values were analyzed using a one-stage coagulation assay at screening, and immediately before (baseline) and at 0.5, 1, 1.5, 2, 5, 12, 24, and 48 hours and 4, 7, 14, 21, 28, 42, and 56 days after the start of study drug administration. Blood samples for 1208

prothrombin time (PT) and activated partial thromboplastin time (APTT) were collected on day –1 (admission); at 5, 12, 24, and 48 hours and 4, 7, 14, and 56 days after the start of IV infusion in all subjects; and at 21, 28, and 42 days if still abnormal at the previous visit. Platelet aggregation induced by 1.5-, 5-, and 10-μM adenosine diphosphate and 1- and 2-mg/mL ristocetin (Platelet Aggregation Profiler-4, Bio/Data Corporation, Horsham, Pennsylvania) and bleeding time (Surgicutt bleeding time device, ICT, New Edison, New Jersey) were conducted on day –1 (admission) and 5 hours after the start of the infusion.

Statistical Analysis The pharmacokinetic properties of TB-402 were determined using noncompartmental analysis. Data from subjects who received placebo from the younger age group were combined. Categoric data were presented using counts and percentages, and continuous variables were presented using mean (SD) and/or median (range) and proportion of subjects. APTT and FVIII:C were analyzed using general linear mixed models.16 The mixed models included a random intercept and slope over time as random effects to model correlations between the different time points. As main effects, the predose value of the variable of interest was included, and the time since study drug administration (planned visits) was included as a categoric variable. Primarily, the randomized dose was included as a categoric variable, and at each time point, the difference versus the placebo group was estimated for all groups that received TB-402. In a further analysis, the dosage was included as a continuous variable after logarithm transformation. Such an analysis is consistent with the assessment of a log-linear trend in the outcome as dose increases. Trends were assessed at each time point separately and overall. For APTT, no measurement was taken if the measurement at the previous visit was normal on days 14, 21, 28, and 42. In these cases, the baseline value was imputed to prevent bias. All tests were 2-sided and assessed at the 5% significance level. No adjustments were made to the significance level to account for multiple testing. All analyses were conducted using SAS version 9.2 software (SAS Institute Inc., Cary, North Carolina).

RESULTS Disposition of Subjects and Baseline Characteristics Fifty-seven subjects were randomized. One subject who received the 188-μg/kg dose was withdrawn before Volume 32 Number 6

P. Verhamme et al. any trial medication was administered because of suspected respiratory disease and was replaced. Due to withdrawal of consent before randomization, 5 subjects were assigned to receive the 0.1- and 12.5-μg/kg doses; consequently, one of the placebo treatments in each group was dropped. Fifty-six subjects were exposed to a single intravenous infusion of TB-402 or matching placebo over 1 hour. The highest tolerated dose in the younger group, 1860 μg/kg, was administered to the older group. The demographic characteristics of the subjects are summarized in Table I.

Tolerability Thirty-one of the 38 subjects who received TB-402 (82%) experienced a total of 85 treatment-emergent AEs (TEAEs), and 14 of 18 subjects who received placebo (78%) experienced 35 TEAEs. The AEs were generally mild (109/120 [91%]); 6 were considered moderate, and 5 were considered severe. The most common AEs reported in subjects who received TB-402 were headache (11 [29%]), vessel puncture-site hematoma (7 [18%]), and traumatic hematoma (5 [13%]); with placebo, they were vessel puncture-site hematoma (4 [22%]), headache (3 [17%]), vasovagal reaction (3 [17%]), and hematuria (3 [17%]). Ninety-nine of the AEs were considered unrelated or unlikely to be related to study drug, and 21 events were deemed to be possibly related to study drug administration. TEAEs are summarized in Table II. One subject who

received TB-402 0.5 μg/kg reported 3 episodes of generalized seizures on days 12 and 54 after administration. The subject had a family history of late-onset epilepsy. These events were considered as both severe and serious but were considered unrelated to the study drug. Two subjects who received TB-402 620 μg/kg reported events that were considered by the investigator to be severe: 1 subject reported vomiting, and 1 subject had 3 AEs of toothache, 1 of which was severe. The subjects recovered completely, and the events were considered unrelated to the study drug. Five participants reported 6 AEs that were considered to be moderate; all of these events were considered unrelated to the study drug (gastroenteritis [2], bone pain, joint sprain, pharyngolaryngeal pain, and vasovagal reaction [1 each]). One participant experienced transient urticaria after the administration of TB-402. This AE was resolved after 1.5 hours, without therapy. Changes in laboratory results, vital sign measurements, ECG, or physical examination did not give rise to any tolerability concerns in any of the groups. Although some of the laboratory test results fell outside of the reference ranges for the laboratory, none were considered clinically significant by the principal investigator, and none were recorded as AEs.

Bleeding Events Bleeding events were of specific interest in the trial. A total of 34 bleeding events were reported in 13 of

Table I. Baseline demographic and clinical characteristics of the healthy male subjects in this study of the tolerability and pharmacokinetics of TB-402.* TB-402 (Age 18–45 y)

TB-402 (Age 55–75 y)

Active (n = 34)

Placebo (n = 16)

Active (n = 4)

Placebo (n = 2)

Age, y Mean (SD) Median (range)

27.4 (6.7) 24.5 (20–45)

28.5 (7.3) 25.5 (21–43)

64.5 (3.0) 64.0 (62–68)

67.0 (12.7) 67.0 (58–76)

Weight, kg Mean (SD) Median (range)

78.0 (11.0) 76.5 (64.5–103.8)

81.1 (11.9) 80.8 (60.4–101.6)

79.8 (3.6) 79.0 (76.8–84.2)

84.7 (13.2) 84.7 (75.3–94.0)

Height, cm Mean (SD) Median (range)

180.3 (5.4) 180.0 (166.0–190.0)

181.4 (7.3) 180.0 (170.0–200.0)

178.3 (7.8) 176.0 (172.0–189.0)

180.5 (10.6) 180.5 (173.0–188.0)

Characteristic

*All of the subjects were white.

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1209

1210 0 0 0 1 (50) 0 0 0 0 0 0

Immune system disorders Seasonal allergy

Infections and infestations Nasopharyngitis Gastroenteritis Fungal infection Fungal skin infection Eye infection Herpes simplex Localized infection

1 (50) 0 0 0 0 0 0

0

General disorders and administration-site conditions Vessel puncture site hematoma Pyrexia

Gastrointestinal disorders Oral mucosal blistering Diarrhea Nausea Toothache Vomiting Abdominal distention Rectal hemorrhage

Cardiac disorders Palpitations

AE

0.015 (n = 2)

0 0 0 0 0 0 0

0

0 0

0 0 0 0 0 0 0

0

0.1 (n = 4)

0 1 (25)§ 0 0 0 0 0

0

1 (25) 0

0 0 0 0 0 0 0

0

0.5 (n = 4)

1 (25) 0 0 0 0 0 0

0

0 0

0 0 0 0 0 0 0

0

2.5 (n = 4)

0 1 (25)§ 0 0 0 0 0

0

0 0

0 0 0 0 0 0 0

0

12.5 (n = 4)

0 0 0 0 0 0 0

0

3 (75) 1 (25)

0 1 (25) 0 0 0 0 0

0

37.5 (n = 4)

1 (25) 0 0 0 0 0 0

1 (25)

1 (25) 0

0 0 0 0 0 0 0

0

188 (n = 4)

TB-402 Dose, μg/kg

0 0 0 0 0 0 0

0

0 0

0 0 1 (25) 1 (25)† 1 (25)‡ 0 0

0

620 (n = 4)

0 0 0 0 0 0 0

1 (25)

2 (50) 0

0 1 (25) 0 0 0 0 0

1 (25)

1860 (Age 18–45 y) (n = 4)

0 0 1 (25) 1 (25) 0 0 0

0

0 0

0 0 0 0 0 0 0

0

2 (11) 0 0 0 1 (6) 1 (6) 1 (6)

0

4 (22) 0

0 2 (11) 0 0 0 1 (6) 1 (6)

0

Placebo (n = 18)

(continued)

1860 (Age 55–75 y) (n = 4)

Table II. Treatment-emergent adverse events (AEs)* after the administration of a single intravenous bolus injection of TB-402 or placebo in healthy male volunteers. Data are number (%) of subjects.

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June 2010 0 0 0 0 0 0 0

0 0 0 0 0 0 1 (50) 0 0 0 0

Investigations Blood sodium increased Weight loss

Musculoskeletal and connective tissue disorders Arthralgia Muscle spasms Bone pain Pain in extremity Back pain Myalgia

Nervous system disorders Dizziness Dysesthesia Grand mal convulsion Headache Vasovagal syncope

0.015 (n = 2)

Injury, poisoning, and procedural complications Traumatic hematoma Contusion Joint sprain Excoriation Sternal injury

AE

Table II (continued).

0 1 (25) 0 0 0

1 (25) 0 0 0 0 0

0 0

1 (25) 0 0 0 0

0.1 (n = 4)

0 0 1 (25) < 0 0

0 0 0 0 0 0

0 0

0 0 0 0 0

0.5 (n = 4)

0 0 0 2 (50) 0

0 0 0 0 0 0

0 0

1 (25) 2 (50) 1 (25)§ 0 0

2.5 (n = 4)

0 1 (25) 0 0 0

0 0 0 0 0 0

0 0

0 0 0 0 0

12.5 (n = 4)

0 0 0 2 (50) 0

0 0 0 0 0 0

0 0

2 (50) 0 0 1 (25) 1 (25)

37.5 (n = 4)

0 0 0 0 0

0 1 (25) 0 0 0 0

0 0

0 0 0 0 0

188 (n = 4)

TB-402 Dose, μg/kg

0 0 0 3 (75) 0

0 0 0 0 0 0

0 0

0 0 0 0 0

620 (n = 4)

0 0 0 2 (50) 0

0 0 1 (25)§ 0 0 0

0 0

1 (25) 0 0 0 0

1860 (Age 18–45 y) (n = 4)

0 0 0 2 (50) 0

0 0 0 1 (25) 0 0

0 0

0 0 0 0 0

0 0 0 3 (17) 3 (17)¶

1 (6) 0 0 1 (6) 1 (6) 1 (6)

1 (6) 1 (6)

0 0 0 0 0

Placebo (n = 18)

(continued)

1860 (Age 55–75 y) (n = 4)

P. Verhamme et al.

1211

1212 1 (25) 0

1 (25) 0 0 0

0 0

0

1 (25)

0

0.1 (n = 4)

0 1 (25)

2 (50) 0 0 0

0 0

0

1 (25)

0

0.5 (n = 4)

0 0

0 0 0 0

1 (25) 0

1 (25)

0

0

2.5 (n = 4)

0 0

0 0 0 0

0 1 (25)§

0

0

0

12.5 (n = 4)

0 0

0 0 0 0

0 0

0

0

0

37.5 (n = 4)

0 0

0 0 0 0

1 (25) 0

0

0

1 (25)

188 (n = 4)

TB-402 Dose, μg/kg

0 0

1 (25) 1 (25) 0 0

0 0

0

0

0

620 (n = 4)

0 0

0 0 0 0

0 0

0

0

0

1860 (Age 18–45 y) (n = 4)

0 0

0 0 1 (25) 0

0 0

0

0

0

1860 (Age 55–75 y) (n = 4)

0 0

0 0 0 1 (6)

1 (6) 2 (11)

0

3 (17)

0

Placebo (n = 18)

* By Medical Dictionary for Regulatory Activities14 system organ class and preferred term. † This event occurred in 3 cases in 1 subject and was considered by the investigator as severe in 1 case. All 3 cases were considered unrelated to the study drug. ‡ This event was considered by the investigator as severe and unrelated to the study drug. § This event was considered by the investigator as moderate and unrelated to the study drug. < This event was considered by the investigator as severe, serious, and unrelated to the study drug. The subject had a family history of late-onset epilepsy. ¶ In 1 subject, this event was considered by the investigator as moderate and unrelated to the study drug.

0 0

1 (50) 0

Respiratory, thoracic and mediastinal disorders Epistaxis Pharyngolaryngeal pain

Vascular disorders Flushing Hematoma

0

Reproductive system and breast disorders Hematospermia

0 0 0 0

0

Renal and urinary disorders Hematuria

Skin and subcutaneous tissue disorders Erythema Dry skin Rash Seborrheic dermatitis

0

0.015 (n = 2)

Psychiatric disorder Sleep disorder

AE

Table II (continued).

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P. Verhamme et al. 38 subjects who received TB-402 (34%) and 7 of 18 subjects who received placebo (39%). In the 13 TB-402–treated subjects who reported bleeding events, 10 events in 6 subjects (46%) were considered possibly related to the study drug by the masked investigator; of the 7 subjects who received placebo who reported bleeding events, the events were considered related to the study drug in 6 subjects (86%). All of the bleeding events, which were predominantly vessel puncture-site hematomas, were rated as mild and not serious. Overall, there was no indication of an increased prevalence of bleeding events in TB-402–treated subjects compared with placebo, nor was there an indication of an increased prevalence of bleeding events in the higher-dose groups. The bleeding events are summarized in Table III.

Immunogenicity In one subject, a positive TB-402 antibody response was recorded 28 days after the administration of TB-402 0.5 μg/kg, but the screening assay was negative on days 42 and 56. TB-402 antibody formation was not observed in any of the other subjects.

Pharmacokinetics At doses ranging from 0.1 to 37.5 μg/kg, the LLOQ for the TB-402 concentration was reached on day 1 after administration. Therefore, the data did not allow the estimation of the pharmacokinetic parameters in the subjects in these groups. Mean serum TB-402 concentration–time curves with doses ≥37.5 μg/kg are shown in the figure, and key pharmacokinetic parameters for the highest dose groups are shown in Table IV. In the 1860-μg/kg dose groups, the concentrations from the linear part of the semilog plot is reported over 2 to 3 half-lives of TB-402, allowing appropriately calculated elimination parameters. Less than 20% of the AUC0–∞ at the 2 highest dose levels was extrapolated, while ~50% extrapolation was built into the AUC0–∞ with the 188-μg/kg dose. Therefore, CL, Vss, and dose proportionality were most reliably assessed in the groups that received the 2 highest doses. TB-402 was found to have calculated secondary t1/2 values of 22.9 days (18to-45–year age group) and 19.5 days (55-to-75–year age group), CL values of 2.8 and 3.1 mL/kg/d, respectively, and Vss values of 84.4 and 76.3 mL/kg, respectively (Table IV). A dose-proportional increase in exposure was found when the 2 highest doses were compared, with a 3.5-fold increase in AUC0–∞ at a 3-fold dose increase. June 2010

Coagulation No significant differences in FVIII:C versus placebo were observed with the 0.015- to 0.5-μg/kg doses (Table V). Decreases in FVIII:C versus baseline and placebo were first observed with the 2.5-μg/kg dose. In the subjects treated with ≥37.5-μg/kg TB-402, FVIII:C was generally decreased from baseline by one third to two thirds. Lowering of FVIII:C generally occurred within 0.5 hour after administration and peaked between 0.5 and 2 hours. After an initial decrease in FVIII:C, a recovery of the FVIII:C was observed within ~48 hours (Table V). No persistent FVIII:C lowering was observed at any of the doses at ≥96 hours after TB-402 administration. No significant changes in APTT versus placebo were observed at the 0.015- to 0.5-μg/kg doses (Table VI). APTT was prolonged, to ~1.1- to 1.2-fold baseline at doses ≥2.5 μg/kg in both age groups. This effect was observed from 5 hours after TB-402 administration. The extent of APTT prolongation was not increased with TB-402 dose, but the duration of the APTT prolongation was increased with increased dose. APTT measurements were significantly prolonged until 24 hours after the administration of the 12.5-μg/kg dose, until day 4 after the administration of the 37.5-μg/kg dose, until day 7 after the administration of the 189-μg/kg dose, until day 42 after the administration of the 620-μg/kg dose, and until the end of the study at day 56 (end of study) after the administration of the 1860-μg/kg dose (Table VI). There was no apparent effect of TB-402 on platelet aggregation tests, bleeding time, and PT (data not shown).

DISCUSSION Bleeding events are of special interest when a new antithrombotic strategy is assessed. In this ascending-dose, randomized, double-blind, placebo-controlled study in healthy male subjects, TB-402 appeared to be well tolerated. No significant differences in bleeding events between TB-402 and placebo were observed, nor was there an apparent relationship between increasing concentrations of TB-402 and increased bleeding events. One subject experienced transient urticaria after the administration of TB-402. This AE was resolved after 1.5 hours, without therapy. There was no evidence of an increased rate of AEs with TB-402 compared with placebo. The pharmacokinetic profiles in these healthy male subjects were comparable to a TB-402 t1/2 of ~3 weeks, in line with the reported t1/2 of human IgG4.3 After 1213

1214 0 1 (25) 1 (25) 0 0 0 0

1 (50) 0 0 0 0 0 0

0.1 (n = 4)

1 (25) 1 (25) 0 0

0 1 (25) 0

0.5 (n = 4)

0 0 1 (25) 0

1 (25) 0 1 (25)

2.5 (n = 4)

0 0 0 0

0 0 0

12.5 (n = 4)

*By Medical Dictionary for Regulatory Activities14 system organ class and preferred term.

Epistaxis Hematuria Traumatic hematoma Vessel puncture site hematoma Hematoma Hematospermia Rectal hemorrhage

AE

0.015 (n = 2)

3 (75) 0 0 0

0 0 2 (50)

37.5 (n = 4)

1 (25) 0 0 0

1 (25) 0 0

188 (n = 4)

TB-402 Dose, μg/kg

0 0 0 0

0 0 0

620 (n = 4)

2 (50) 0 0 0

0 0 1 (25)

1860 (Age 18–45 y) (n = 4)

0 0 0 0

0 0 0

1860 (Age 55–75 y) (n = 4)

4 (22) 0 0 1 (6)

1 (6) 3 (17) 0

Placebo (n = 18)

Table III. Treatment-emergent bleeding adverse events* (AEs) after the administration of a single intravenous bolus injection of TB-402 in healthy male subjects. Data are number (%) of subjects.

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P. Verhamme et al.

37.5 μg/kg 188 μg/kg 620 μg/kg 1860 μg/kg (age 18–45 y) 1860 μg/kg (age 55–75 y)

Plasma TB-402 Concentration (μg/mL)

100

10

1

0

20

40

60

Time After Study Drug Administration (d) Figure. Mean plasma drug concentrations over time after the administration of a single-dose intravenous bolus injection of TB-402 37.5, 188, 620, and 1860 μg/kg in healthy male subjects (n = 4 per group).

Tmax, serum TB-402 concentrations decreased in a generally biphasic manner at each dose level. No increase of the clearance of the antibody was observed over the entire follow-up period, in agreement with the lack of immune response to the antibody. The effect of TB-402 on FVIII:C did not differ at doses ≥37.5 μg/kg. FVIII:C was transiently lower after the administration of TB-402 and returned to predose values within ~48 hours after administration. The reason for the apparent normalization of FVIII:C is not completely understood. FVIII:antigen could not be measured in this study because all of the assays that had been assessed were strongly affected by the presence of TB-402. It is not expected that the normalization of FVIII:C was due to disappearance or inactivation of TB-402 because the concentrations of TB-402 were measured in a competition assay that detected only functional TB-402. TB-402 administration was associated with a persistent prolongation of the APTT of ~1.1- to 1.2-fold baseline values at doses ≥12.5 μg/kg. The observation that the administration of higher doses of TB-402 did not affect June 2010

the extent of APTT prolongation is consistent with the in vitro findings that increasing the concentration of TB-402 did not significantly affect the anticoagulant properties after maximal FVIII:C inhibition was achieved.2 Increasing the dose in vivo was expected to have prolonged the pharmacodynamic effect. The duration of the APTT prolongation was dose dependent, with a statistically significant APTT prolongation until day 7 after the administration of the 188-μg/kg dose, until day 42 after the administration of the 620-μg/kg dose, and until day 56 (end of study) at the highest dose. The discrepancy between the transient lowering of FVIII:C for ~48 hours and the dose-dependent duration of the APTT prolongation might be linked to the different sensitivities of these 2 types of assays to the inhibitory activity of TB-402. Differences toward the inhibitory effect of TB-402 have also been observed between FVIII:C assays. In a preclinical study, TB-402 was associated with significantly reduced thrombus growth in an extracorporeal shunt thrombosis model but was not associated with significantly reduced FVIII:C measured using a 1-stage FVIII:C assay.10 1215

Clinical Therapeutics

Table IV. Pharmacokinetic (PK) properties after the administration of a single intravenous bolus injection of TB-402 in healthy male subjects (n = 4 subjects per group). TB-402 Dose, μg/kg

188

620

1860 (Age 18–45 y)

1860 (Age 55–75 y)

Cmax, μg/mL Mean (SD) Median (range)

3.9 (0.6) 4.0 (3.2–4.4)

19.5 (10.5) 15.4 (12.4–35.0)

51.2 (18.4) 46.2 (35.0–77.5)

79.8 (28.3) 87.6 (40.9–103.0)

Tmax, h Mean (SD) Median (range)

1.6 (0.5) 1.8 (1.0–2.0)

3.3 (2.0) 3.5 (1.1–5.0)

1.5 (0.4) 1.5 (1.0–2.0)

4.4 (5.1) 2.1 (1.5–12.0)

AUC0–∞, μg/mL/d Mean (SD) Median (range)

26.4 (7.9) 25.7 (18.0–36.1)

213.5 (35.4) 222.9 (163.0–245.1)

692.0 (115.8) 693.6 (564.2–816.4)

643.5 (170.4) 631.3 (449.9–861.6)

AUC, % extrapolated Mean (SD) Median (range)

49.6 (14.0) 55.4 (28.7–58.7)

17.8 (5.8) 18.6 (10.2–23.9)

17.7 (5.4) 17.2 (11.8–24.7)

12.7 (3.6) 11.6 (9.9–17.8)

t1/2, d Mean (SD) Median (range)

6.9 (3.4) 8.0 (2.1–9.6)

14.6 (2.7) 15.4 (10.8–16.7)

22.9 (3.7) 22.9 (18.6–27.4)

19.5 (3.1) 19.2 (16.0–23.6)

CL, mL/kg/d Mean (SD) Median (range)

7.7 (2.3) 7.5 (5.2–10.5)

3.0 (0.6) 2.8 (2.5–3.8)

2.8 (0.5) 2.8 (2.3–3.3)

3.1 (0.8) 3.0 (2.2–4.1)

Vss, mL/kg Mean (SD) Median (range)

69.8 (18.5) 75.2 (43.8–85.0)

65.6 (8.7) 65.8 (54.7–76.0)

84.4 (4.9) 83.5 (80.0–90.6)

76.3 (12.7) 73.3 (64.5–94.2)

PK Parameter

CL = total body clearance; Vss = apparent volume of distribution at steady state.

TB-402 may offer a strategy to minimize the risk for overdosing and bleeding complications due to its apparent partial inhibition of the target coagulation factor irrespective of the excess of the drug. The major risk for targeting FVIII with an antithrombotic agent is that of causing complete inhibition of FVIII:C. Patients with severe hemophilia (FVIII:C <1) experience spontaneous bleeding. However, the limited inhibition of FVIII:C might prevent thrombosis without an increased risk for major bleeding, as observed in patients with mild hemophilia or in carriers of hemophilia A.17,18 Thus, in humans, partial inhibition would likely be sufficient and effective in reducing the risk for thrombosis. The tolerability and preliminary efficacy of TB-402 in patients undergoing a total knee replacement are being 1216

investigated (unpublished observations, http://clinical trials.gov/ct2/show/NCT00793234?term=NCT00793 234&rank=1, 2008). The low plasma FVIII:C (0.2 μg/mL) is a potential benefit of TB-402. By comparison, Factor IX, a target of another anticoagulant antibody that has completed Phase I clinical development,19 is present at a 50-fold higher concentration in plasma. Due to its long t1/2, TB-402 may have a thromboprophylactic effect after single-dose administration, without a need for monitoring, allowing single-dose administration for extended prophylaxis of venous thromboembolism. This study had several limitations. The tolerability and pharmacokinetics of TB-402 were assessed only in healthy male subjects. Further studies are needed to Volume 32 Number 6

June 2010

0.1 (–0.4 to 0.5) 0.0 (–0.5 to 0.5) –0.2 (–0.7 to 0.3) –0.1 (–0.5 to 0.4) –0.3 (–0.7 to 0.2) –0.1 (–0.6 to 0.4) –0.1 (–0.6 to 0.4) –0.2 (–0.7 to 0.3) –0.1 (–0.6 to 0.4) –0.2 (–0.7 to 0.3) –0.4 (–0.9 to 0.1) –0.1 (–0.6 to 0.4) –0.2 (–0.7 to 0.3) –0. 2 (–0.7 to 0.3) –0.0 (–0.5 to 0.5)

0.015 –0.1 (–0.5 to 0.2) –0.1 (–0.4 to 0.3) –0.2 (–0.6 to 0.1) –0.0 (–0.4 to 0.3) –0.2 (–0.6 to 0.1) –0.3 (–0.6 to 0.1) –0.3 (–0.6 to 0.1) 0.0 (–0.3 to 0.4) 0.3 (–0.0 to 0.7) 0.0 (–0.4 to 0.4) –0.2 (–0.6 to 0.2) 0.1 (–0.2 to 0.5) 0.1 ( –0.3 to 0.5) –0.2 (–0.6 to 0.2) 0.2 (–0.2 to 0.6)

0.1 –0.1 (–0.5 to 0.2) –0.2 (–0.6 to 0.2) –0.4 < (–0.7 to –0.0) –0.2 (–0.6 to 0.1) –0.3 (–0.6 to 0.1) –0.1 (–0.4 to 0.3) –0.2 (–0.6 to 0.1) –0.1 (–0.5 to 0.3) –0.1 (–0.5 to 0.2) 0.0 (–0.3 to 0.4) –0.1 (–0.4 to 0.3) 0.1 (–0.3 to 0.4) –0.1 (–0.4 to 0.3) 0.3 (–0.1 to 0.7) 0.5< (0.1 to 0.9)

0.5 –0.1 (–0.4 to 0.3) –0.1 (–0.4 to 0.3) –0.6‡ (–1.0 to –0.3) –0.4 < (–0.8 to –0.1) –0.6‡ (–1.0 to –0.2) –0.1‡ (–0.5 to 0.2) 0.0 (–0.3 to 0.4) 0.3 (–0.1 to 0.7) 0.3 (–0.1 to 0.7) 0.4 (–0.0 to 0.7) –0.3 (–0.7 to 0.1) 0.2 (–0.2 to 0.6) 0.4 < (0.1 to 0.8) –0.0 (–0.4 to 0.4) 0.5 < (0.1 to 0.9)

2.5 –0.2 (–0.6 to 0.1) –0.4 < (–0.7 to –0.0) –0.5§ (–0.8 to –0.1) –0.0 (–0.4 to 0.3) –0.5§ (–0.9 to –0.1) –0.9‡ (–1.3 to –0.6) 0.3 (–0.1 to 0.6) –0.3 (–0.6 to 0.1) 0.1 (–0.3 to 0.5) 0.0 (–0.4 to 0.4) –0.1 (–0.5 to 0.3) –0.4 < (–0.8 to –0.0) –0.2 (–0.7 to 0.2) –0.0 (–0.4 to 0.4) –0.1 (–0.5 to 0.3)

12.5

188 –0.6‡ (–1.0 to –0.3) –0.5§ (–0.9 to –0.2) –0.7‡ (–1.0 to –0.3) –0.5§ (–0.9 to –0.2) –0.7‡ (–1.0 to –0.3) –0.7§ (–1.1 to –0.2) –0.7‡ (–1.1 to –0.3) –0.5§ (–0.9 to –0.1) –0.1 (–0.4 to 0.3) 0.1 (–0.3 to 0.5) –0.1 (–0.5 to 0.2) –0.2 (–0.6 to 0.2) 0.3 (–0.1 to 0.7) –0.1 (–0.5 to 0.3) 0.1 (–0.3 to 0.5)

37.5 –0.8‡ (–1.1 to –0.4) –0.8‡ (–1.1 to –0.4) –0.9‡ (–1.2 to –0.5) –0.7‡ (–1.1 to –0.4) –0.9‡ (–1.2 to –0.5) –0.8§ (–1.1 to –0.4) –0.8‡ (–1.2 to –0.5) –0.8‡ (–1.1 to –0.4) 0.1 (–0.3 to 0.4) –0.1 (–0.4 to 0.3) –0.4 < (–0.8 to –0.0) –0.0 (–0.4 to 0.3) 0.1 (–0.3 to 0.5) –0.1 (–0.6 to 0.3) –0.0 (–0.4 to 0.4)

TB-402 Dose, μg/kg

*An overall test for the existence of a log-linear dose-response association yields a P value <0.001. †Test for dose-response. ‡P < 0.001. §P < 0.01. < P < 0.05.

56 d

42 d

28 d

21 d

14 d

7d

4d

48 h

24 h

12 h

5h

2h

1.5 h

1h

0.5 h

Time After Study Drug Administration –0.5§ (–0.9 to –0.1) –0.5< (–0.9 to –0.1) –0.8§ (–1.2 to –0.3) –0.5< (–0.8 to –0.1) –0.5§ (–0.9 to –0.2) –0.5§ (–0.8 to –0.1) –0.7‡ (–1.0 to –0.3) –0.3 (–0.7 to 0.0) –0.1 (–0.5 to 0.2) –0.2 (–0.6 to 0.2) –0.0 (–0.4 to 0.4) –0.3 (–0.7 to 0.1) 0.1 (–0.3 to 0.5) –0.1 (–0.5 to 0.3) 0.2 (–0.2 to 0.6)

620 –0.6‡ (–0.9 to –0.3) –0.6‡ (–0.8 to –0.3) –0.7‡ (–1.0 to –0.4) –0.5‡ (–0.8 to –0.2) –0.6‡ (–0.9 to –0.3) –0.5‡ (–0.8 to –0.2) –0.6‡ (–0.9 to –0.4) –0.2 (–0.5 to 0.1) –0.2 (–0.4 to 0.1) –0.2 (–0.5 to 0.1) –0.3 < (–0.6 to –0.0) –0.0 (–0.3 to 0.3) –0.3 (–0.6 to 0.0) –0.4 < (–0.7 to –0.1) –0.1 (–0.5 to 0.2)

1860

0.491

0.052

0.626

0.144

0.129

0.351

0.294

0.002

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

P†

Table V. Treatment differences in Factor VIII concentration (IU) after the administration of a single intravenous bolus injection of TB-402 or placebo in healthy male subjects (n = 4 subjects per group).* Data are Δ (95% CI).

P. Verhamme et al.

1217

1218

–0.1 (–2.9 to 2.7) 0.3 (–2.5 to 3.1) 2.2 (–0.6 to 5.0) 1.7 (–1.1 to 4.5) 2.4 (–0.4 to 5.2) 2.6 (–0.3 to 5.4) 0.6 (–2.3 to 3.4) 0.6 (–2.3 to 3.4) 0.2 (–2.7 to 3.0) 0.2 (–2.6 to 3.1) –1.1 (–3.9 to 1.8)

0.015 1.4 (–0.7 to 3.4) 2.3§ (0.3 to 4.4) 0.7 (–1.4 to 2.7) 0.9 (–1.2 to 3.0) 1.6 (–0.4 to 3.7) 1.8 (–0.3 to 3.9) 0.8 (–1.3 to 2.9) 0.5 (–1.5 to 2.6) 0.2 (–1.9 to 2.3) 0.2 (–1.9 to 2.3) –1.1 (–3.2 to 1.1)

0.1 0.8 (–1.3 to 2.8) –1.0 (–3.1 to 1.0) 0.3 (–1.7 to 2.4) –0.7 (–2.7 to 1.4) –0.5 (–2.5 to 1.6) –0.0 (–2.1 to 2.0) –0.5 (–2.6 to 1.5) –0.0 (–2.1 to 2.0) –0.4 (–2.5 to 1.6) –0.4 (–2.5 to 1.7) –2.9† (–5.0 to –0.8)

0.5

12.5 8.8‡ (6.7 to 10.8) 9.5‡ (7.4 to 11.5) 5.3‡ (3.2 to 7.4) 1.3 (–0.8 to 3.4) –0.2 (–2.3 to 1.9) –1.3 (–3.4 to 0.8) –0.1 (–2.2 to 2.0) 0.4 (–1.7 to 2.5) 0.0 (–2.1 to 2.2) 0.1 (–2.0 to 2.2) –1.2 (–3.3 to 0.9)

2.5 3.4† (1.3 to 5.5) 0.8 (–1.2 to 2.9) –1.8 (–3.9 to 0.3) –0.1 (–2.2 to 2.0) –0.1 (–2.2 to 2.0) –1.7 (–3.8 to 0.4) –0.9 (–3.0 to 1.2) –0.4 (–2.5 to 1.7) –0.8 (–2.9 to 1.3) –0.8 (–2.9 to 1.3) –1.8 (–3.9 to 0.3)

37.5 9.3‡ (7.1 to 11.6) 5.6‡ (3.5 to 7.7) 6.7‡ (4.6 to 8.8) 5.2‡ (3.1 to 7.3) 2.2§ (0.1 to 4.3) 0.3 (–1.7 to 2.4) 0.3 (–1.8 to 2.4) 0.3 (–1.8 to 2.4) –0.3 (–2.4 to 1.8) –0.7 (–2.9 to 1.4) –0.8 (–2.9 to 1.3)

TB-402 Dose, μg/kg

* An overall test for the existence of a log-linear dose-response association yields a P value <0.001. † P < 0.01. ‡ P < 0.001. § P < 0.05.

56 d

42 d

28 d

21 d

14 d

7d

4d

48 h

24 h

12 h

5h

Time After Study Drug Administration 7.0‡ (4.9 to 9.0) 6.2‡ (4.1 to 8.2) 5.7‡ (3.7 to 7.8) 4.0‡ (1.9 to 6.0)‡ 3.0† (0.9 to 5.0) 2.4§ (0.3 to 4.4) 0.1 (–1.9 to 2.2) 1.9 (–0.2 to 4.0) 2.0 (–0.1 to 4.1) 1.3 (–0.8 to 3.4) –1.5 (–3.6 to 0.6)

188 5.8‡ (3.7 to 7.8) 4.7‡ (2.7 to 6.8) 4.1‡ (2.0 to 6.1) 4.6‡ (2.5 to 6.6) 3.3† (1.2 to 5.3) 4.2‡ (2.1 to 6.3) 3.2† (1.1 to 5.3) 4.0‡ (1.9 to 6. 0) 5.1‡ (3.0 to 7.1) 2.6§ (0.5 to 4.7) 0.6 (–1.5 to 2.7)

620

5.3‡ (3.7 to 6.9) 4.5‡ (2.9 to 6.1) 2.8‡ (1.2 to 4.4) 1.9§ (0.4 to 3.5) 2.4† (0.8 to 4.0) 3.2‡ (1.6 to 4.8) 3.2‡ (1.6 to 4.8) 4.0‡ (2.4 to 5.5) 2.3† (0.7 to 3.9) 2.1§ (0.5 to 3.8) 3.0‡ (1.4 to 4.6)

1860

0.057

0.030

0.001

<0.001

0.003

<0.001

0.002

<0.001

<0.001

<0.001

<0.001

P†

Table VI. Treatment differences in activated partial thromboplastin time (seconds) after the administration of a single intravenous bolus injection of TB-402 or placebo in healthy male subjects (n = 4 subjects per group).* Data are Δ (95% CI).

Clinical Therapeutics

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P. Verhamme et al. address the tolerability in other populations and to investigate the pharmacodynamic effects of TB-402. 3.

CONCLUSIONS In this study, TB-402 was well tolerated in these healthy male subjects. The observed pharmacokinetics and partial inhibition of FVIII suggest potential use of TB-402 for long-acting thromboprophylaxis in patients at high risk for thrombosis. The findings from this study warrant further investigation in preclinical and clinical studies.

4.

5.

6.

ACKNOWLEDGMENTS The study was sponsored by ThromboGenics NV and BioInvent International AB, codevelopers of TB-402. Dr. Verhamme is coholder of the Pfizer Chair in Atherothrombosis, University of Leuven; has received research funding through the University of Leuven from ThromboGenics; and has been a member of the speakers’ bureaus and/or scientific advisory boards at Bayer Pharmaceuticals Corporation, Boehringer-Ingelheim GmBH, LEO Pharma A/S, and the sanofi-aventis Group. Dr. Pakola holds stock options in ThromboGenics. Dr. Saint-Remy has received research grants from Biotest AG, Octapharma AG, UCB Pharma SA, Wyeth Pharmaceuticals s.a./n.v., and ZLB Behring, and honoraria for lectures from Biotest, Novo Nordisk A/S, and Wyeth. Ms. Cahillane holds stock options in ThromboGenics. Dr. Stassen has received consultant’s fees from, and holds equity in, ThromboGenics. Dr. Peerlinck is holder or coholder of Wyeth, Baxter SA, and CSL K.U. Leuven Chairs in Hemophilia and Allied Bleeding Disorders. Dr. Jacquemin is coholder of the Baxter Chair in Hemophilia and has received research funding or honoraria through the University of Leuven from Baxter, Bayer, Wyeth, and ThromboGenics. All of the authors were involved in the design of the study, analysis of the data, and writing of the manuscript. The authors have indicated that they have no other conflicts of interest regarding the content of this article.

7.

8.

9.

10.

11.

12.

13.

14.

15.

REFERENCES 1. Weitz JI, Hirsh J, Samama MM, for the American College of Chest Physicians. New antithrombotic drugs: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) [published correction appears in Chest. 2008;134:473]. Chest. 2008;133(Suppl 6): 234S–256S.

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2. Jacquemin M, Radcliffe CM, Lavend’homme R, et al. Variable region heavy chain glycosylation determines the anti-

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Address correspondence to: Peter Verhamme, MD, PhD, Center for Molecular and Vascular Biology, University of Leuven, Herestraat 49, B-3000 Leuven, Belgium. E-mail: [email protected] 1220

Volume 32 Number 6