Page 123 - Haematologica Vol. 107 - September 2022

ARTICLE - Effects of BT200 on VWF/FVIII in humans K.D. Kovacevic et al.
ful testing of the anti-VWF nanobody caplacizumab in phase II/III trials and its subsequent marketing authoriza- tion for acquired thrombotic thrombocytopenic purpura. Aptamer-mediated blockade of VWF A1-domains was also demonstrated to be effective in patients with a gain-of- function VWF mutation (type 2B von Willebrand disease [VWD]), increasing both VWF and FVIII plasma levels, as well as platelet counts.18,19 These pro-hemostatic actions might also be exploited therapeutically. Previous gener- ations of anti-VWF aptamers, for example aptamer ARC1779, had a suboptimal short half-life11, 20 or subopti- mal stability at higher temperatures. For those reason we designed a next-generation VWF-A1-binding aptamer, BT200, which recently showed good subcutaneous bio- availability (≥77%) and a long half-life in non-human pri- mates (>100 h).21 This first-in-human, randomized, double-blind, placebo-controlled trial set out to test the hypothesis that BT200 is well tolerated, safe and has fa- vorable pharmacokinetics and pharmacodynamic effects.
Methods
This trial was approved by the national competent auth- ority (BASG) and the Ethics Committee of the Medical University of Vienna. The study protocol, subsequent amendments, and informed consent were written ac- cording to the Declaration of Helsinki and the trial was conducted according to the International Council on Har- monization guidelines for Good Clinical Practice, which was monitored by an external contract research organ- ization. Patients provided written informed consent prior to their participation in the trial. This trial was registered under EUDRA-CT# 2019-001818-42 and NCT04103034 at www.clinicaltrials.gov. This was a single-center trial and all authors had open access to the primary clinical data. Upon a justified request, the principal investigator will grant access to the primary clinical trial data.
This trial used a 3:1 randomized, double-blind, placebo- controlled integrated protocol design with 14 dose co- horts. Each cohort comprised six subjects receiving active treatment and two receiving placebo. Placebo- treated volunteers were pooled within each part of the study and analyzed together. Randomization was done centrally using an electronic system provided by Assign Data Management and Biostatistics (Innsbruck, Austria). Part A of the study was a single ascending dose study, part B a multiple ascending dose study, part D an intra- venous (IV) bioavailability study (IV infusion over 24 h) and part C was a drug-drug interaction study with the VWF secretagogue, desmopressin, given as a single dose (0.3 mg/kg IV over 30 min) approximately 96 h after ad- ministration of 48 mg BT200 (i.e., at approximately the tmax of BT200). Healthy male or female subjects of non-
childbearing potential were invited to participate. Be- cause reproductive toxicology studies do not exist at this point, the relevant regulatory agency recommended ex- cluding women of childbearing potential at this early stage of development. After written informed consent and passing a screening examination subjects received single doses of BT200 ranging from 0.18 to 24 mg via sub- cutaneous (SC) injection (cohorts 1-7), SC infusion (drug diluted in 100 mL NaCl) of 24, 36 and 48 mg over 1 h (co- horts 8-10) or a 24-hour IV infusion of 24 mg (cohort 11) (Table 1). Subjects were confined to bed rest for the first hour; oxygen saturation and heart rate were monitored, and blood pressure was measured repeatedly. Subjects in the multiple-dose cohorts received a split loading dose (IV over 2 h/SC) of 12/12 mg or 24/24 mg. In cohort 13 this was followed by weekly SC injections of 12 mg until day 28.
BT200 is a fully 2’-O-methylated RNA aptamer21 con- jugated to a 40 kD polyethylene glycol, and it was sup- plied at a concentration of 15 mg/mL in sterile saline for injection (all doses refer to the unconjugated aptamer). A sterile saline solution (0.9 NaCl) was used as placebo
Table 1. Enrolled study population and treatment.
Study Part
Cohort
Treatment
N
A
1
0.18 mg BT200/placebo – SC injection
8
A
2
0.6 mg BT200/placebo – SC injection
8
A
A
3
4
1.8 mg BT200/placebo – SC injection
8
6 mg BT200/placebo – SC injection
8
A
5
12 mg BT200/placebo – SC injection
8
A
6
18 mg BT200/placebo – SC injection
8
A
7
24 mg BT200/placebo – SC injection
8
A
A
8
9
24 mg BT200/placebo – SC infusion
8
36 mg BT200/placebo – SC infusion
8
A
10
48 mg BT200/placebo – SC infusion
8
D
C
B
11
12
24 mg BT200/placebo – IV infusion
In each cohort six volunteers were randomized to BT200 and two to placebo. N: number of subjects; SC: subcutaneous; IV: intravenous.
8
48 mg BT200/placebo – SC injection with desmopressin challenge
8
13
24 mg BT200/placebo – IV infusion with 12 mg SC injection, followed by 4 weekly doses of 12 mg
8
B
14
24 mg BT200/placebo – IV infusion with 24 mg SC injection
8
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