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W. Li et al.
and rapid reversal of the pharmacodynamic effect (25 min from an ACT of ~ 400 s
to ≤ 170 s) is observed following cessation of treatment. In a pig CPB model, it
was administered at dosages to maintain ACTs ≥ 400 s throughout a 3 h bypass
procedure and compared with saline controls. This aptamer prevented clot formation
while clots formed in the circuits of the control animals [2, 9].
The result of phase 1a and phase 1b clinical trials demonstrated that intravenous
injection of NU172 dose-dependently increased the ACT of healthy volunteers
without serious adverse events [44]. Nowadays, a phase 2 trial of NU172 in patients
undergoing off-pump CABG surgery is underway (NCT00808964) (https://clinicalt
rials.gov).
The antidote (AD)-mediated controllability is vital for regulating the bioavailability effect of aptamers with chemical modifications. The aptamer/AD-complexes
and neutralization of both aptamers NU172 and R10-60 (39-mer) against Toll-like
receptor 9 (TLR9) were analyzed in human serum at 37 °C. Afterward, ACT for
NU172 and the related gene expression of IFN-1β, IL-6, CXCL-10, and IL-1β for
R10-60 was determined to evaluate the blocking effects of two aptamers. Gel electrophoresis showed that aptamer/AD-complexes between aptamer NU172 and R1060 and complementary AD were formed rapidly just in 2 min of incubation in human
serum. A rapid reversal of anticoagulant activity of NU172 by AD in 5 min was also
demonstrated in fresh human whole blood. In addition, the TLR9-mediated activation of PMDC05 cells was blocked after the addition of the R10-60 AD. Furthermore, the rapid antagonism of the aptamers NU172 and R10-60 was confirmed in
different environments. The studies suggested that the aptamer/AD-complexes are
promising drug molecules for different applications, for example, neutralization of
aptamer-based drugs, immobilization, or targeting the delivery of oligonucleotide
drugs [45].
In phase 2 clinical trials for heart disease, NU172 as an anticoagulant was much
more effective in thrombin inhibition than TBA. The crystal structure of the thrombinNU172 complex revealed that the aptamer had a bimodular duplex/quadruplex architecture targeting thrombin exosite I. NU172 bound to exosite I of thrombin through a
highly complementary surface involving all three loops of the G-quadruplex module.
The structural features of the duplex/quadruplex junction and the solution data of
NU172 mutants indicate that in fact the duplex domain does not interact directly
with thrombin, whereas the duplex moiety is very important for optimization of
the protein–ligand interaction as well as inhibition of enzyme activity. Troisi et al.
disclosed the structural features in inhibition of thrombin by NU172 to design aptamer
mutants with improved properties. The structural characterization of the thrombinNU172 complex and related mutants suggests that the coexistence of several motifs
may be associated with the thrombin inhibition properties of NU172 [46].
Constantly monitored hemostasis status and detection of bleeding or coagulation
disorders are vital during open-heart surgery. Kunnakattu and his group members
established a novel optimized piezo-based measuring system (PIEZ) for the rheological evaluation of NU172
s effect on coagulation and hemostasis status. Their
PIEZ system can be applied to analyze and monitor blood clotting and coagulation
of the aptamer drugs, as well as to evaluate aptamer’s antidotes’ reversal function.
W. Li et al.
and rapid reversal of the pharmacodynamic effect (25 min from an ACT of ~ 400 s
to ≤ 170 s) is observed following cessation of treatment. In a pig CPB model, it
was administered at dosages to maintain ACTs ≥ 400 s throughout a 3 h bypass
procedure and compared with saline controls. This aptamer prevented clot formation
while clots formed in the circuits of the control animals [2, 9].
The result of phase 1a and phase 1b clinical trials demonstrated that intravenous
injection of NU172 dose-dependently increased the ACT of healthy volunteers
without serious adverse events [44]. Nowadays, a phase 2 trial of NU172 in patients
undergoing off-pump CABG surgery is underway (NCT00808964) (https://clinicalt
rials.gov).
The antidote (AD)-mediated controllability is vital for regulating the bioavailability effect of aptamers with chemical modifications. The aptamer/AD-complexes
and neutralization of both aptamers NU172 and R10-60 (39-mer) against Toll-like
receptor 9 (TLR9) were analyzed in human serum at 37 °C. Afterward, ACT for
NU172 and the related gene expression of IFN-1β, IL-6, CXCL-10, and IL-1β for
R10-60 was determined to evaluate the blocking effects of two aptamers. Gel electrophoresis showed that aptamer/AD-complexes between aptamer NU172 and R1060 and complementary AD were formed rapidly just in 2 min of incubation in human
serum. A rapid reversal of anticoagulant activity of NU172 by AD in 5 min was also
demonstrated in fresh human whole blood. In addition, the TLR9-mediated activation of PMDC05 cells was blocked after the addition of the R10-60 AD. Furthermore, the rapid antagonism of the aptamers NU172 and R10-60 was confirmed in
different environments. The studies suggested that the aptamer/AD-complexes are
promising drug molecules for different applications, for example, neutralization of
aptamer-based drugs, immobilization, or targeting the delivery of oligonucleotide
drugs [45].
In phase 2 clinical trials for heart disease, NU172 as an anticoagulant was much
more effective in thrombin inhibition than TBA. The crystal structure of the thrombinNU172 complex revealed that the aptamer had a bimodular duplex/quadruplex architecture targeting thrombin exosite I. NU172 bound to exosite I of thrombin through a
highly complementary surface involving all three loops of the G-quadruplex module.
The structural features of the duplex/quadruplex junction and the solution data of
NU172 mutants indicate that in fact the duplex domain does not interact directly
with thrombin, whereas the duplex moiety is very important for optimization of
the protein–ligand interaction as well as inhibition of enzyme activity. Troisi et al.
disclosed the structural features in inhibition of thrombin by NU172 to design aptamer
mutants with improved properties. The structural characterization of the thrombinNU172 complex and related mutants suggests that the coexistence of several motifs
may be associated with the thrombin inhibition properties of NU172 [46].
Constantly monitored hemostasis status and detection of bleeding or coagulation
disorders are vital during open-heart surgery. Kunnakattu and his group members
established a novel optimized piezo-based measuring system (PIEZ) for the rheological evaluation of NU172
s effect on coagulation and hemostasis status. Their
PIEZ system can be applied to analyze and monitor blood clotting and coagulation
of the aptamer drugs, as well as to evaluate aptamer’s antidotes’ reversal function.