Safety, Tolerability, and Pharmacokinetics of the Intravenous S-Nitrosoglutathione Reductase
Inhibitor N6022: An Ascending-Dose Study in Subjects Homozygous for the F508del-CFTR Mutation
Scott Donaldson1, Jennifer Taylor-Cousar2, Daniel Rosenbluth3, Pamela Zeitlin4, James Chmiel5, Manu Jain6, Karen McCoy7, Edith Zemanick8 For the SNO-1
Multicenter Study Group.
University of North Carolina, Chapel Hill, NC, USA; National Jewish Health,
Denver, CO, USA; 3 Washington University School of Medicine, St Louis, MO, USA;
4 Johns Hopkins University, Baltimore, MD, USA; 5 Rainbow Babies and Children’s
Hospital, Cleveland, OH, USA; 6 Northwestern University Feinberg School of
Medicine, Chicago, Il; 7 Nationwide Children’s Hospital, Columbus, OH, USA; 8
Children’s Hospital Colorado, Aurora, CO, USA.
Abstract
Background: Preservation of S-nitrosoglutathione (GSNO), through inhibition of
its primary catabolizing enzyme S-nitrosoglutathione reductase (GSNOR), may
provide a novel therapeutic strategy in cystic fibrosis (CF). In experimental
models, small molecule inhibitors of GSNOR have been shown to improve the
function of F508del-CFTR and inhibit inflammatory mediators that correlate with
lung function decline in CF.
Objectives: The aims of this study were to assess the safety, tolerability, and
pharmacokinetics of ascending doses of the first-in-class GSNOR inhibitor, N6022,
in F508del-CFTR homozygous adults. Biomarker assessments of CFTR function
and inflammation were also explored. Information from this trial will inform the
design and dosing strategy for an oral dosage form, N91115.
Methods: This was a double-blind, randomized, placebo-controlled trial in which
4 sequential ascending doses of N6022 were assessed (5, 10, 20, and 40 mg/day)
followed by a confirmatory cohort of subjects at the highest dose. Subjects were
dosed once daily for 7 days with a single intravenous injection of N6022 or
placebo. An independent Data Monitoring Committee (DMC) adjudicated dose
escalation at the completion of each cohort after review of unblinded safety data.
Results: Sixty six subjects (40 female and 26 male) were included in the study.
At baseline, subjects had a mean age of 29 ± 8 years, a mean percent predicted
FEV1 of 70 ± 21%, and a mean sweat chloride of 101 ± 11 mmol/L. There were no
significant differences among the treatment groups at baseline. No dose limiting
side effects were detected and N6022 was well-tolerated over the dose range
studied. The overall frequency, severity and types of adverse events was similar
among the treatment groups, including cardiac (ECG, telemetry, and 24-Hour
Holter monitoring) and laboratory safety profiling. There were no beneficial effects
on FEV1, sweat chloride, or nasal potential difference during this short term of
treatment. However, encouraging trends were observed with certain inflammatory
markers (hsCRP, MMP3, and IL-6). The highest dose of N6022 assessed, 40
mg/day, resulted in a mean maximal plasma concentration (Cmax) of 9.5 μM, which
was well-tolerated.
Conclusions: Seven days of IV N6022 was safe and well tolerated. These safety
and PK data pave the way for studies with N91115, a follow-on oral GSNOR
inhibitor with a more favorable PK profille. N91115 has shown significant efficacy in
experimental models at a Cmax of 2.7 μM, which is well below the lowest dose
limiting Cmax observed to date in animal toxicology studies (72 μM).
SNO-1 Study Outline
Primary Objective:
To assess the safety and tolerability intravenous (IV) N6022, administered 7
consecutive days, in cystic fibrosis (CF) subjects who are homozygous for the
F508del-CFTR mutation
Secondary Objective:
• To assess the pharmacokinetics of N6022 at 4 dose levels
• To examine the effects of N6022 on:
o Pulmonary function (Spirometry/FEV1)
o Biomarkers of Cystic Fibrosis Transmembrane Conductance Regulator
(CFTR) activity, as assessed by sweat chloride and nasal potential difference
• To guide selection of N6022 doses for future studies
Exploratory Objectives:
• To explore effects of N6022 on patient-reported outcomes
• To explore effects of N6022 on biomarkers of inflammation and gene expression
Design:
Double-blind, randomized, placebo controlled, multicenter, sequential doseescalation study
Safety and Tolerability
Intravenous N6022 was well tolerated with no dose limiting toxicities when
administered once daily over 7 days up to a maximum of 40 mg. The table below
outlines treatment emergent adverse events (TEAE) occurring in more than one
subject in any dose group.
5 mg
N=10
10 mg
N=9
20 mg
N=9
40 mg
N=19
Placebo
N=19
At least one TEAE
9 (90%)
9 (100%)
9 (100%)
15 (78.9%)
18 (94.7%)
Headache
1(10.0%)
1(11.1%)
2(22.2%)
1(5.3%)
1(5.3%)
10000
Therapeutic Target of
0.4 µM, based on
N91115
1000
100
10
N6022 5 mg (N=10)
1
N6022 10 mg (N=9)
0.1
N6022 20 mg (N=8)
N6022 40 mg (N=8)
0.01
0
4
Parosmia
0(0.0%)
0(0.0%),
2(22.2%)
0(0.0%)
0(0.0%)
Cough
3(30.0%)
1(11.1%)
3(33.3%)
2(10.5%)
7(36.8%)
Increased bronchial
secretions
2(20.0%)
2(22.2%)
2(22.2%)
1(5.3%)
3(15.8%)
Nasal congestion
3(30.0%)
0(0.0%)
0(0.0%)
1(5.3%)
1(5.3%)
Chest tightness
2(20.0%)
1(11.1%)
0(0.0%)
2(10.5%)
1(5.3%)
8
12
16
20
24
Time (h)
Exploratory Effects
• There were no beneficial effects on FEV1 (Figure 2), sweat chloride, and nasal
potential difference
• There were encouraging trends observed with certain inflammatory markers:
hsCRP, MMP3, and IL-6 (Figure 3)
Figure 2 FEV1 % Predicted During Treatment and after 7 Days Follow-up
80.0
75.0
Placebo (N=19)
N6022 40 mg (N=18)
70.0
N6022 5 mg (N=10)
N6022 10 mg (N=9)
65.0
N6022 20 mg (N=9)
60.0
55.0
PreTx
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 14
Figure 3 Plasma Biomarkers of Inflammation: Day 7 – Baseline Comparing
Placebo (N=17) with all N6022 Treated Subjects (N=45)
P = 0.06
Mean
Rales
3(30.0%)
Night sweats
0(0.0%)
0(0.0%)
1(11.1%)
2(22.2%)
0(0.0%)
0(0.0%)
0(0.0%)
0(0.0%)
0(0.0%)
Pharmacokinetics
t½
AUCinf
Vz
CL
(μg/mL)
(h)
(h*μg/mL)
(L)
(L/h)
5 (n=10)
0.63
4.92
0.22
165
23.2
10 (n=9)
1.34
4.23
0.37
161
26.4
20 (n=8)
1.45
3.13
0.72
124
27.5
40 (n=8)
3.42
2.86
1.94
85
20.6
• N6022 exposures (Cmax and AUC) increased linearly with increases in dose.
Figure 1 shows plasma concentrations on Day 1
• The pharmacokinetic (PK) profile of N6022 in cystic fibrosis (CF) subjects was
similar to that observed at the same (or similar) doses in healthy subjects
• There was no evidence of drug accumulation following repeat dosing.
• Even at the highest dose, within 2 hours drug levels had fallen below an efficacy
target level (0.4 µM). This target is based on preclinical models of CFTR
modulation (Figure 1) using an oral GSNOR inhibitor, N91115.
Presented at the 28th Annual North American Cystic Fibrosis Conference, October 9-11, 2014, Atlanta, GA.
Median
P = 0.25
P = 0.08
Summary and Conclusions
Cmax
N6022 IV
Dose (mg)
Introduction
N6022 is a potent and selective inhibitor of S-nitrosoglutathione reductase
(GSNOR) and is the first GSNOR inhibitor to be studied in man. GSNOR is the
major catabolic enzyme of S-nitrosoglutathione (GSNO), which has an important
role in controlling nitric oxide (NO) signaling in vivo (Hess et al. 2005, Hogg 2002)
and exists in equilibrium with other nitrosated proteins, collectively termed SNOs
(Liu et al. 2001, Liu et al. 2004, Smith and Marletta 2012). Depleted levels of
GSNO are implicated in the pathophysiology of CF (Grasemann et al. 1999) .
Restoring GSNO levels has been shown to improve F508del-CFTR function in
both in vitro and in vivo preclinical models.
Figure 1 Plasma concentrations of N6022 measured on Day 1 at 5 mg, 10 mg,
20 mg, and 40 mg administered intravenously
(ng/mL)
Plasma Conc.
(ng/mL)
Conc.
N6022N6022
Plasma
2
FEV1 % Predicted
1
• Intravenous N6022 was well tolerated with no dose limiting toxicities when
administered once daily over 7 days, up to a maximum of 40 mg (Cmax of 9.5 µM)
• N6022 exposures (Cmax and AUC) were linear with increases in dose
• Systemic concentrations with intravenous N6022 are not sustained above a target
efficacy level suggested by preclinical models of CFTR modulation.
References
• Grasemann et al. J Pediatr 1999;135(6):770-772
• Hess DT et al. Nat Rev Mol Cell Biol 2005;6(2):150-166.
• Hogg N. Annu Rev Pharmacol Toxicol.2002; 42: 585600.
• Liu L et al. Nature 2001;410(6827):490-494.
• Liu L et al. Cell 2004; 20;116(4): 617-628.
• Smith BC et al Curr Opin Chem Biol 2012;16(5-6):498506
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