CLINICAL PHARMACOLOGY
Mechanism Of Action
Within the blood, the acoustic
impedance of Lumason microspheres is lower than that of the surrounding
non-aqueous tissue. Therefore, an ultrasound beam is reflected from the
interface between the microspheres and the surrounding tissue. The reflected ultrasound
signal provides a visual image that shows a contrast between the blood and the
surrounding tissues.
For ultrasonography of the
urinary tract in pediatric patients, the intravesically administered Lumason
microspheres increase signal intensity of fluids within the urethra, bladder,
ureters, and renal pelvis.
Pharmacodynamics
Lumason provides useful
echocardiographic signal intensity for two minutes after intravenous injection.
Lumason microspheres are destroyed and contrast enhancement decreases as the
mechanical index increases (values of 0.8 or less are recommended).
For ultrasonography of the
liver, Lumason provides dynamic patterns of differential signal intensity
enhancement between focal liver lesions and liver parenchyma during the
arterial, portal venous, and late phase of signal intensity enhancement of the
microvasculature.
In ultrasonography of the
urinary tract, Lumason facilitates the detection of reflux of fluid from the
bladder into the ureters.
Pulmonary Hemodynamic Effects
The effect of Lumason on
pulmonary hemodynamics was studied in a prospective, open-label study of 36
patients scheduled for right heart catheterization, including 18 with mean
pulmonary arterial pressure (MPAP) > 25 mmHg and 18 with MPAP ≤ 25 mmHg.
No clinically important pulmonary hemodynamic changes were observed. This study
did not assess the effect of Lumason on visualization of cardiac or pulmonary
structures.
Pharmacokinetics
The pharmacokinetic of the SF6
gas component of Lumason was evaluated in 12 healthy adult subjects. After
intravenous bolus injections of 0.03 mL/kg and 0.3 mL/kg of Lumason,
corresponding to approximately 1 and 10 times the recommended doses,
concentrations of SF6 in blood peaked within 1 to 2 minutes for both
doses. The terminal half-life of SF6 in blood was approximately 10
minutes for the 0.3 mL/kg dose. The area-under-the-curve of SF6 was
dose-proportional over the dose range studied.
Distribution
In a study of healthy subjects,
the mean values for the apparent steady-state volume of distribution of SF6
following intravenous administration, were 341 mcL and 710 mcL for Lumason
doses of 0.03 mL/kg and 0.3 mL/kg, respectively. Preferential distribution to
the lung is likely responsible for these values.
Elimination
Following intravenous
administration, the SF6 component of Lumason is eliminated via the
lungs. In a clinical study that examined SF6 elimination twenty
minutes following Lumason injection, the mean cumulative recovery of SF6 in
expired air was 82 ± 20% (SD) at the 0.03 mL/kg dose and 88 ± 26% (SD) at the
0.3 mL/kg dose.
SF6 undergoes first
pass elimination within the pulmonary circulation; approximately 40% to 50% of
the SF6 content was eliminated in the expired air during the first
minute following Lumason injection.
Metabolism
SF6 undergoes little
or no biotransformation; following intravenous administration, 88% of an
administered dose is recovered unchanged in expired air.
Pharmacokinetics In Specific
Populations
Pulmonary Impairment
In a study of patients with
pulmonary impairment, blood concentrations of SF6 peaked at 1 to 4
minutes following intravenous Lumason administration. The cumulative recovery
of SF6 in expired air was 102 ± 18% (mean ± standard deviation), and
the terminal half-life of SF6 in blood was similar to that measured
in healthy subjects.
Clinical Studies
Echocardiography
Adults
A total of 191 patients with suspected cardiac disease
and suboptimal non-contrast echocardiography received Lumason in three
multi-center controlled clinical trials (76 patients in Study A, 62 patients in
Study B, and 53 patients in Study C). Among these patients, there were 127 men
and 64 women. The mean age was 59 years (range 22 to 96 years). The racial and
ethnic representations were 79% White, 16% Black, 4% Hispanic, < 1% Asian,
and < 1% other racial or ethnic groups. The mean weight was 204 lbs (range
92 to 405 lbs). Approximately 20% of the patients had a chronic pulmonary
disorder and 30% had a history of heart failure. Of the 106 patients for whom a
New York Heart Association (NYHA) classification of heart failure was assigned,
49% were Class I, 33% were Class II, and 18% were Class III. Patients with NYHA
Class IV heart failure were not included in these studies.
In Studies A and B, each patient received four
intravenous bolus injections of Lumason (0.5, 1, 2, and 4 mL), in randomized
order. In Study C, each patient received two doses of Lumason (1 mL and 2 mL)
in randomized order. All three studies assessed endocardial border delineation
and left ventricular opacification. For each patient in each study,
echocardiography with Lumason was compared to non-contrast (baseline)
echocardiography. A recording of 2D echocardiography was obtained from 30
seconds prior to each injection to at least 15 minutes after dosing or until
the disappearance of the contrast effect, whichever was longer. Contrast and
non-contrast echocardiographic images for each patient were evaluated by two
independent reviewers, who were blinded to clinical information and the Lumason
dose. Evaluation of left ventricular endocardial border consisted of segment
based assessment involving six endocardial segments and using two apical views
(2-and 4-chamber views).
Endocardial Border Delineation And Duration Of Useful
Contrast Effect
In all three studies, administration of Lumason improved
left ventricular endocardial border delineation. The majority of the patients
who received a 2 mL dose of Lumason had improvement in endocardial border
delineation manifested as visualization of at least two additional endocardial
border segments. Table 3 demonstrates the improvement in endocardial border
delineation following Lumason administration as a reduction in percentage of
patients with inadequate border delineation in at least one pair of adjacent
segments (combined 2-chamber and 4-chamber view). The results are shown by
reader.
Table 3: Reduction in Percentage of Patients with
Inadequate BorderDelineation
Reader |
Study A
N = 76 |
Study B
N = 62 |
Study C
N = 53 |
Non- contrast |
Lumason |
Non- contrast |
Lumason |
Non- contrast |
Lumason |
A |
60 (79%) |
22 (33%) |
31 (50%) |
12 (19%) |
12 (23%) |
10 (19%) |
B |
62 (82%) |
29 (37%) |
54 (87%) |
6 (10%) |
45 (85%) |
20 (38%) |
Following the first appearance
of contrast within the left ventricle the mean duration of useful contrast
effect ranged from 1.7 to 3.1 minutes.
Left Ventricular Opacification
In all three studies, complete
left ventricular opacification was observed in 52% to 80% of the patients
following administration of a 2 mL dose of Lumason. The studies did not
sufficiently assess the effect of Lumason upon measures of left ventricular
ejection fraction and wall motion.
Pediatric Patients
Twelve pediatric patients 9 to
17 years of age with suspected cardiac disease and suboptimal non-contrast
echocardiography received Lumason in one prospective multi-center clinical
trial. Patients received Lumason at a dose of 0.03 mL/kg (mean 1.83 mL). There
were 7 female, 10 white, and 2 black patients.
For both the non-contrast and
contrast-enhanced images, standard apical 4-, 2-, and 3chamber views with
harmonic imaging were acquired. Contrast and non-contrast images for each
patient were evaluated by three independent reviewers, who were blinded to
clinical information.
Endocardial Border Delineation
Evaluation of left ventricular
endocardial border delineation consisted of segment-based assessment of the
left ventricle divided into 17 endocardial segments. The delineation of each
segmentâ⬙s endocardial border was rated as inadequate, sufficient, or good. An
exam was considered suboptimal if any of the patientâ⬙s apical views had 2 or
more adjacent segments with inadequate delineation scores.
The majority of screened patients had adequate
delineation of the left ventricular endocardial border without administration
of contrast. The number of patients with inadequate left ventricular
endocardial border delineation without contrast and after Lumason are shown for
the 12 patients, by reader, in Table 4.
Table 4: Number of Pediatric Patients with Inadequate
Border Delineation with and without Lumason
|
Reader A |
Reader B |
Reader C |
Non-contrast |
12/12 |
11/11b |
12/12 |
Lumason |
1/11a |
0/9bb |
0/11c |
a Reader A had missing segment data with
contrast echocardiography for one patient;
b Reader B had missing segment data with non-contrast
echocardiography for one patient;
bb Reader B had missing segment data with contrast echocardiography
for three patients;
c Reader C had missing segment data with contrast echocardiography
for one patient |
Left Ventricular Opacification
Complete left ventricular
opacification was observed in all the patients by all 3 readers following
administration of Lumason.
Ultrasonography Of The Liver
Adults
A total of 499 patients with at
least 1 focal liver lesion requiring characterization were evaluated in two
studies (259 patients in Study A, 240 patients in Study B). Among these
patients, there were 259 men and 240 women. The mean age was 56 years (range 19
to 93 years). The racial and ethnic representations were 74% White, 11% Black,
9% Hispanic, 5% Asian, and 1% other racial or ethnic groups. The mean weight
was 80 kg (range 44 to 173 kg).
In both studies, prior to
Lumason administration, gray scale and Doppler (color or power imaging)
ultrasound examinations of the target lesion were performed using commercially
available ultrasound equipment and using standard techniques. Each patient
received an intravenous injection of 2.4 mL of Lumason (up to 2 injections were
allowed, 91% patients received 1 injection). Following Lumason administration,
ultrasound examination of the target lesion was carried out using
contrast-specific imaging modes operating at MI ≤ 0.4. The probe was
positioned to provide optimal visualization over the target lesion and was kept
in the same position for at least 180 seconds.
Truth standard included:
histology/surgery, contrast CT, contrast MRI, and/or 6 month follow-up.
For each study, the
interpretation of images was conducted by three independent readers who were
blinded to clinical data. Lesions were characterized as malignant or benign.
Separate blinded readers assessed the truth standard images. Results of both
studies demonstrated an improvement in characterization of focal liver lesions
using Lumason ultrasound compared to non-contrast ultrasound images. Table 5
summarizes the efficacy results by reader.
Table 5: Diagnostic Performance of Lumason Ultrasound
for Characterization of FocalLiver Lesions
Study A: |
|
Sensitivity (patients with malignant lesions)
N=119 |
Specificity (patients with benign lesions)
N=140 |
Lumason % |
Non-contrast % |
Difference (95% CI) |
Lumason % |
Non-contrast % |
Difference (95% CI) |
Reader 1 |
87* |
49 |
38 (30, 54) |
71 |
63 |
8 (-4, 21) |
Reader 2 |
76* |
35 |
41 (29, 52) |
83* |
54 |
29 (21, 44) |
Reader 3 |
92* |
16 |
76 (67, 84) |
73* |
22 |
51 (40, 61) |
Study B: |
|
Sensitivity (patients with malignant lesions)
N=124 |
Specificity (patients with benign lesions)
N=116 |
Lumason % |
Non-contrast % |
Difference (95% CI) |
Lumason % |
Non-contrast % |
Difference (95% CI) |
Reader 4 |
65 |
53 |
12 (-1, 23) |
72* |
24 |
48 (35, 58) |
Reader 5 |
61* |
41 |
20 (7, 32) |
67* |
7 |
60 (50, 70) |
Reader 6 |
47 |
66 |
-19 (-31, -7) |
88* |
59 |
29 (18, 40) |
*Statistically
significant improvement from non-contrast (p<0.05 based on McNemarâ⬙s test) |
Pediatric Patients
In one published study, 44
patients with an indeterminate focal liver lesion (23 males, 21 females, age
range: 4-18 years, median 11.5 years) were evaluated after intravenous bolus
administration of 1.2 to 2.4 mL of Lumason. The findings of Lumason ultrasound
images were compared to CT, MRI or histology. Specificity was 98% (43/44
patients).
Ultrasonography Of The Urinary
Tract
Pediatric Patients
The efficacy of Lumason for the
evaluation of pediatric patients with suspected or known vesicoureteral reflux
was established in two published open-label single center studies (A and B).
Patients received 1 mL of Lumason intravesically and underwent voiding
urosonography (VUS). Patients were also evaluated with voiding
cystourethrography (VCUG) as the reference standard. The presence or absence of
urinary reflux with Lumason ultrasound was compared to the radiographic
reference standard.
Study A evaluated 183 patients
(94 male, 89 female; age 2 days -44 months) with a total of 366 kidney-ureter
units. The images were interpreted by one on-site reader, blinded to the
reference standard. Out of 103 reference standard-positive images, Lumason VUS
was positive in 89 units and falsely negative in 14 units. In 263 units with
negative reference standard, the Lumason ultrasonography was negative in 226
and falsely positive in 37.
Study B evaluated 228 patients
(123 male, 105 female; age 6 days -13 years) with a total of 463 kidney-ureter
units (some patients had more than 2 units). The images were interpreted
independently by two on-site readers, blinded to the reference standard. Out of
71 reference standard positive images, Lumason ultrasonography was positive in
57 and falsely negative in 14. In 392 units with negative reference standard,
Lumason ultrasonography was negative in 302 and falsely positive in 90.