CLINICAL PHARMACOLOGY
Mechanism Of Action
XEOMIN blocks cholinergic transmission at the
neuromuscular and salivary neuroglandular junction by inhibiting the release of
acetylcholine from peripheral cholinergic nerve endings. This inhibition occurs
according to the following sequence: neurotoxin binding to cholinergic nerve
terminals, internalization of the neurotoxin into the nerve terminal,
translocation of the light-chain part of the molecule into the cytosol of the
nerve terminal, and enzymatic cleavage of SNAP25, a presynaptic target protein
essential for the release of acetylcholine. In both muscles and glands, impulse
transmission is re-established by the formation of new nerve endings.
Pharmacodynamics
The return of increased muscle tone following injection
typically occurs within 3 to 4 months.
Pharmacokinetics
General characteristics of the active substance:
Using currently available analytical technology, it is
not possible to detect XEOMIN in the peripheral blood following intramuscular
or intraglandular injection at the recommended doses.
Clinical Studies
Chronic Sialorrhea
The efficacy and safety of XEOMIN for the treatment of
chronic sialorrhea were evaluated in a double-blind, placebo-controlled
clinical trial that enrolled a total of 184 patients with chronic sialorrhea
resulting from Parkinson's disease, atypical parkinsonism, stroke, or traumatic
brain injury, that was present for at least three months. Patients with a
history of aspiration pneumonia, amyotrophic lateral sclerosis, salivary gland
or duct malformation, and gastroesophageal reflux disease were excluded. The
study consisted of a 16-week main phase, followed by an extension period of
dose-blinded treatment with XEOMIN.
In the main phase, a fixed total dose of XEOMIN (100
Units or 75 Units) or placebo was administered into the parotid and
submandibular salivary glands in a 3:2 dose ratio. The co-primary efficacy
variables were the change in unstimulated Salivary Flow Rate (uSFR, Table 9)
and the change in Global Impression of Change Scale (GICS, Table 10) at Week 4
post-injection. A total of 173 treated patients completed the main phase of the
study. For both the uSFR and GICS, XEOMIN 100 Units was significantly better
than placebo (see Table 9 and Table 10). XEOMIN 75 Units was not significantly
better than placebo.
Table 9: Change in uSFR (g/min) from Baseline at Week
4, 8, 12, and 16 of Main Phase
|
XEOMIN 100 Units
N = 73 |
Placebo
N=36 |
*Week 4 |
-0.13 |
-0.04 |
Week 8 |
-0.13 |
-0.02 |
Week 12 |
-0.12 |
-0.03 |
Week 16 |
-0.11 |
-0.01 |
*p=0.004 |
Table 10: Mean GICS at Week 4, 8, 12, and 16 of Main Phase
|
XEOMIN 100 Units
N = 74 |
Placebo
N=36 |
*Week 4 |
1.25 |
0.67 |
Week 8 |
1.30 |
0.47 |
Week 12 |
1.21 |
0.56 |
Week 16 |
0.93 |
0.41 |
*p=0.002 |
In the extension period, patients received up to 3
additional treatments with XEOMIN 100 Units or 75 Units every 16±2 weeks, for a
total exposure duration of up to 64 weeks. Patients had periodic dental
examinations to monitor for changes in dentition and oral mucosa. A total of
151 patients completed the extension period.
Upper Limb Spasticity
The efficacy and safety of XEOMIN for the treatment of
upper limb spasticity were evaluated in two Phase 3, randomized, multi-center,
double-blind studies.
Study 1 and Study 2 were both prospective, double-blind,
placebo-controlled, randomized, multi-center trials with an open-label
extension period (OLEX) to investigate the efficacy and safety of XEOMIN in the
treatment of post-stroke spasticity of the upper limb. For patients who had
previously received botulinum toxin treatment in any body region, Study 1 and
Study 2 required that ≥ 12 months and ≥ 4 months, respectively, had
passed since the most recent botulinum toxin administration.
Study 1 consisted of a 12-week main phase followed by
three 12-week OLEX treatment cycles for a total exposure duration of 48 weeks.
The study included 317 treatment-naïve patients who were at least three months
post-stroke in the main study period (210 XEOMIN and 107 placebo). During the
main period, XEOMIN (fixed total dose of 400 Units) and placebo were
administered intramuscularly to the defined primary target clinical pattern
chosen from among the flexed elbow, flexed wrist, or clenched fist patterns and
to other affected muscle groups. 296 treated patients completed the main phase
and participated in the first OLEX cycle. Each OLEX cycle consisted of a single
treatment session (XEOMIN 400 Units total dose, distributed among all affected
muscles) followed by a 12 week observation period.
Study 2 consisted of a 12 - 20 week main phase followed
by an OLEX period of 48 – 69 weeks for up to 89 weeks of exposure to XEOMIN.
The study included 148 treatment-naïve and pre-treated patients with a
confirmed diagnosis of post-stroke spasticity of the upper limb who were at
least six months post-stroke (73 XEOMIN and 75 placebo). During the main
period, for each patient, the clinical patterns of flexed wrist and clenched
fist were treated with fixed doses (90 Units and 80 Units, respectively).
Additionally, if other upper limb spasticity patterns were present, the elbow,
forearm and thumb muscles could be treated with fixed doses of XEOMIN per
muscle. 145 patients completed the main phase and participated in the OLEX
period, during which time the dosing of each involved muscle could be adapted individually.
During the main and OLEX periods, the maximum total dose per treatment session
and 12-week interval was 400 Units.
The average XEOMIN doses injected into specific muscles
and the number of injection sites per muscle in Study 1 and Study 2 are
presented in Table 11.
Table 11: Doses Administered to Individual Muscles
(Main Period) in Study 1 and Study 2 Intent to Treat (ITT)
Muscle Group |
Muscle |
Study 1 Units Injected XEOMIN
N=210 Mean±SD |
Injection Site Per Muscle XEOMIN Median (Min; Max) |
Study 2 Units Injected XEOMIN
N=73 Mean±SD |
Injection Site Per Muscle XEOMIN Median (Min; Max) |
All |
Overall |
400 ± 2 Units |
-- |
307 ± 77 Units |
-- |
Elbow flexors |
Overall |
151 ± 50 Units |
5 (1; 11) |
142 ± 30 Units |
5 (2; 9) |
Biceps |
90 ± 21 Units |
3 (1; 4) |
80 ± 0 Units |
3 (2; 4) |
Brachialis |
52 ± 26 Units |
2 (1; 4) |
50 ± 0 Units |
2 (1; 2) |
Brachioradialis |
43 ± 16 Units |
2 (1; 3) |
60 ± 2 Units |
2 (1; 3) |
Wrist flexors |
Overall |
112 ±43 Units |
4 (1; 6) |
90 ± 0 Units |
4 (4; 4) |
|
58 ± 22 Units |
2 (1; 3) |
50 ± 0 Units |
2 (2; 2) |
Flexor carpi ulnaris |
56 ± 22 Units |
2 (1; 3) |
40 ± 0 Units |
2 (2; 2) |
Finger flexors |
Overall |
104 ± 35 Units |
4 (1; 4) |
80 ± 0 Units |
4 (4; 4) |
Flexor digitorum profundus |
54 ± 19 Units |
2 (1; 2) |
40 ± 0 Units |
2 (2; 2) |
Flexor digitorum superficialis |
54 ± 19 Units |
2 (1; 2) |
40 ± 0 Units |
2 (2; 2) |
Forearm pronators |
Overall |
52 ± 24 Units |
2 (1; 3) |
47 ± 16 Units |
2 (1; 3) |
Pronator quadratus |
26 ± 13 Units |
1 (1; 1) |
25 ± 0 Units |
1 (1; 1) |
Pronator teres |
42 ± 13 Units |
1 (1; 2) |
40 ± 0 Units |
1.5 (1; 2) |
Thumb flexors /adductors |
Overall |
37 ± 25 Units |
2 (1; 4) |
25 ± 10 Units |
1.5 (1; 3) |
Adductor pollicis |
14 ± 8 Units |
1 (1; 1) |
10 ± 0 Units |
1 (1; 1) |
Flexor pollicis brevis / opponens pollicis |
14 ± 9 Units |
1 (1; 1) |
10 ± 0 Units |
1 (1; 1) |
Flexor pollicis longus |
26 ± 16 Units |
1 (1; 2) |
20 ± 0 Units |
1 (1; 1) |
In Study 1, the primary efficacy variable was the change
from baseline in Ashworth Scale (AS) score of the primary target clinical
pattern determined by the investigator at the Week 4 visit. The Ashworth Scale
is a clinical measure of the severity of spasticity by judging resistance to
passive movement. The spasticity of the elbow flexors, wrist flexors, finger
flexors, and thumb muscles as well as the forearm pronators was assessed on the
0 to 4-point Ashworth scale at each visit.
Table 12: Efficacy Results by Patterns of Spasticity
in Study 1, Week 4
|
Mean Change in Ashworth Scale |
XEOMIN
N=171 |
Placebo
N=88 |
Total Primary Target Clinical Pattern (flexed wrist, flexed elbow, and clenched fist) |
-0.9 |
-0.5 |
The analysis is based on Last Observation Carried Forward
in the Intent To Treat population.
p<0.001 |
The co-primary efficacy variable of Study 1 was the
Investigator's Global Impression of Change Scales (GICS) after 4 Weeks of
treatment with XEOMIN or placebo. The GICS is a global measure of a subject’s
functional improvement. Investigators were asked to evaluate the subject’s
global change in spasticity of the upper limb due to treatment, compared to the
condition before the last injection. The response was assessed using a 7-point
Likert scale that ranges from –3 (very much worse) to +3 (very much improved).
A greater percentage of XEOMIN-treated subjects (43%) than placebo-treated
subjects (23%) reported ‘very much improved’ and ‘much improved’ in their
spasticity (see Figure 4).
Figure 4: Investigator’s GICS in Study 1
XEOMIN was considered to be superior to placebo in Study
1 only if statistical significance was reached in both the AS and GICS
variables.
Cervical Dystonia
XEOMIN has been investigated in a Phase 3, randomized,
double-blind, placebo-controlled, multi-center trial in a total of 233 patients
with cervical dystonia. Patients had a clinical diagnosis of predominantly
rotational cervical dystonia, with baseline Toronto Western Spasmodic
Torticollis Rating Scale (TWSTRS) total score ≥20, TWSTRS severity score
≥10, TWSTRS disability score ≥3, and TWSTRS pain score ≥1.
For patients who had previously received a botulinum toxin treatment for cervical
dystonia, the trial required that ≥10 weeks had passed since the most
recent botulinum toxin administration. Patients with swallowing disorders or
any significant neuromuscular disease that might interfere with the study were
excluded from enrollment. Patients were randomized (1:1:1) to receive a single administration
of XEOMIN 240 Units (n=81), XEOMIN 120 Units (n=78), or placebo (n=74). Each
patient received a single administration of 4.8 mL of reconstituted study agent
(XEOMIN 240 Units, XEOMIN 120 Units, or placebo). The investigator at each site
decided which muscles would receive injections of the study agent, the number
of injection sites, and the volume at each site. The muscles most frequently
injected were the splenius capitis/semispinalis, trapezius,
sternocleidomastoid, scalene, and levator scapulae muscles. Table 13 indicates
the average XEOMIN dose, and percentage of total dose, injected into specific
muscles in the pivotal clinical trial.
Table 13: XEOMIN 120 Units Initial Dose (Units and %
of the Total Dose) by Unilateral Muscle Injected During Double Blind Pivotal
Phase 3 Study
|
XEOMIN Dose Injected |
Number of Patients Injected Per Muscle |
Median XEOMIN Units |
75th percentile XEOMIN Units |
Sternocleidomastoid |
63 |
25 |
35 |
Splenius capitis/ Semispiinilis capitis |
78 |
48 |
63 |
Trapezius |
55 |
25 |
38 |
Levator scapulae |
49 |
25 |
25 |
Scalenus (medius and anterior) |
27 |
20 |
25 |
Most patients received a total of 2-10 injections into
the selected muscles. Patients were assessed by telephone at one week
post-injection, during clinic visits at Weeks 4 and 8, and then by telephone
assessments or clinic visits every two weeks up to Week 20.
The mean age of the study patients was 53 years, and 66%
of the patients were women. At study baseline, 61% of patients had previously
received a botulinum toxin as treatment for cervical dystonia. The study was
completed by 94% of study patients. Three patients discontinued the study prematurely
due to adverse events: two patients in the 240 Unit group experienced
musculoskeletal pain and muscle weakness, and one patient in the 120 Unit group
experienced nausea and dizziness.
The primary efficacy endpoint was the change in the
TWSTRS total score from baseline to Week 4 post-injection, in the
intent-to-treat (ITT) population, with missing values replaced by the patient’s
baseline value. In the ITT population, the difference between the XEOMIN 240
Unit group and the placebo group in the change of the TWSTRS total score from
baseline to Week 4 was -9.0 points, 95% confidence interval (CI) -12.0; -5.9
points; the difference between the XEOMIN 120 Unit group and the placebo group
in the change of the TWSTRS total score from baseline to Week 4 was -7.5
points, 95% CI -10.4; -4.6 points.
Figure 5 illustrates the cumulative percentage of
patients from each of the three treatment groups who had attained the specified
change in TWSTRS Score from baseline versus 4 weeks post-injection. Three
change scores have been identified for illustrative purposes, and the percent
of patients in each group achieving that result is shown.
Figure 5: Cumulative Percentage of Patients with
Specified Changes from Baseline TWSTRS Total Score at Week 4
The curves demonstrate that both patients assigned to
placebo and XEOMIN have a wide range of responses, but that the active
treatment groups are more likely to show greater improvements. A curve for an
effective treatment would be shifted to the left of the curve for placebo,
while an ineffective or deleterious treatment would be superimposed upon or
shifted to the right of the curve for placebo.
Comparison of each XEOMIN group to the placebo group was
statistically significant at p<0.001. Initial XEOMIN doses of 120 Units and
240 Units demonstrated no significant difference in effectiveness between the
doses. The efficacy of XEOMIN was similar in patients who were botulinum toxin
naïve and those who had received botulinum toxin prior to this study.
Examination of age and gender subgroups did not identify
differences in response to XEOMIN among these subgroups. There were too few
African-American patients to adequately assess efficacy in that population.
Blepharospasm
XEOMIN has been investigated in a Phase 3, randomized,
double-blind, placebo-controlled, multi-center trial in a total of 109 patients
with blepharospasm. Patients had a clinical diagnosis of benign essential
blepharospasm, with baseline Jankovic Rating Scale (JRS) Severity subscore
≥2, and a stable satisfactory therapeutic response to previous
administrations of onabotulinumtoxinA (Botox). At least 10 weeks had to have
elapsed since the most recent onabotulinumtoxinA administration. Patients with
any significant neuromuscular disease that might interfere with the study were
excluded from enrollment. Patients were randomized (2:1) to receive a single
administration of XEOMIN (n=75) or placebo (n=34). Each patient in the XEOMIN
group received a XEOMIN treatment (dose, volume, dilution, and injection sites
per muscle) that was similar to the most recent onabotulinumtoxinA injection
sessions prior to study entry. The highest dose permitted in this study was 50
Units per eye; the mean XEOMIN dose was 33 Units per eye.
In Table 14 the most frequently injected sites, the
median dose per injection site, and the median number (and range) of injection
sites per eye are presented.
Table 14: Median Dose and Median Number of Injection
Sites per Eye (Blepharospasm)
Injection Area |
Median Units XEOMIN |
Median Number of Injection Sites (Min-Max) |
Temporal Area |
13 |
2 (1 - 6) |
Eyebrow Area |
5 |
1 (1 - 4) |
Upper Lid Area |
10 |
2 (1 - 4) |
Lower Lid Area |
8 |
2 (1 - 3) |
Orbital Rim |
5 |
1 (1 - 3) |
Patients were assessed during clinic visits at Weeks 3
and 6, and then by telephone or at clinic visits every two weeks up to Week 20.
The mean age of the study patients was 62 years, and 65%
of the patients were women. The study was completed by 94% of study patients.
Approximately one third of patients had other dystonic phenomena; in all but 1%
this was limited to facial, cervical, perioral and mandibular muscles. No
patients discontinued the study prematurely due to adverse events.
The primary efficacy endpoint was the change in the JRS
Severity subscore from baseline to Week 6 post-injection, in the
intent-to-treat (ITT) population, with missing values replaced by the patient’s
most recent value (i.e., last observation carried forward). In the ITT population,
the difference between the XEOMIN group and the placebo group in the change of
the JRS Severity subscore from baseline to Week 6 was -1.0 (95% CI -1.4; -0.5)
points. Comparison of the XEOMIN group to the placebo group was statistically
significant at p<0.001.
Figure 6: Frequency Distribution of Changes from
Baseline JRS Severity Subscore at Week 6
Examination of age and gender subgroups did not identify
substantial differences in response to XEOMIN among these subgroups. There were
too few African- American patients to assess efficacy in that population.
Glabellar Lines
Two identically designed randomized, double-blind,
multi-center, placebo controlled clinical trials (Studies GL-1 and GL-2) were
conducted to evaluate XEOMIN for use in the temporary improvement of moderate
to severe glabellar lines. The studies enrolled 547 healthy patients (≥18
years old) with glabellar lines of at least moderate severity at maximum frown.
Three hundred sixty six subjects were treated with 20 Units of XEOMIN and 181
subjects were treated with placebo. Subjects were excluded if they had marked
ptosis, deep dermal scarring, or an inability to lessen glabellar lines, even
by physically spreading them apart. The mean age of study subjects was 46
years. The majority of patients were female (86% and 93% in Studies GL-1 and
GL-2, respectively), and predominantly Caucasian (89% and 65% respectively).
The study subjects received either 20 Units of XEOMIN or an equal amount of
placebo. The total dose was delivered in 5 equally divided intramuscular injections
of 4 Units each to specific sites (see Figure 3). Subjects were followed up for
120 days.
Investigators and subjects assessed efficacy at maximum
frown on Day 30 of treatment using a 4-point scale (0=none, 1=mild, 2=moderate,
3=severe). Composite treatment success was defined as a 2-grade improvement on
this scale compared to baseline for both the investigator’s and subject’s
assessments on Day 30. The percentage of subjects with treatment success was
greater on the XEOMIN arm than the placebo arm at Day 30 in both studies (see
Table 15). The percentage of subjects with composite treatment success at each
visit are presented in Figure 7.
Table 15: Treatment Success at Day 30 (at Least 2
Grades Improvement from Baseline at Maximum Frown)
|
GL-1 |
GL-2 |
XEOMIN
(N=184) |
Placebo
(N=92) |
XEOMIN
(N=182) |
Placebo
(N=89) |
Composite Treatment Success |
111 (60%) |
0 (0%) |
87 (48%) |
0 (0%) |
Investigator Asses sment |
141 (77%) |
0 (0%) |
129 (71%) |
0 (0%) |
Subject Assessment |
120 (65%) |
0 (0%) |
101 (55%) |
1 (1%) |
* Success on both the Investigator and Subject
Assessments |
Figure 7: Percentage of Subjects with Composite
Treatment Success by Visit – Observed Cases (GL-1 and GL-2)