CLINICAL PHARMACOLOGY
Mechanism Of Action
Lanreotide, the active
component of SOMATULINE DEPOT is an octapeptide analog of natural somatostatin.
The mechanism of action of lanreotide is believed to be similar to that of
natural somatostatin.
Pharmacodynamics
Lanreotide has a high affinity
for human somatostatin receptors (SSTR) 2 and 5 and a reduced binding affinity
for human SSTR1, 3, and 4. Activity at human SSTR2 and 5 is the primary
mechanism believed responsible for GH inhibition. Like somatostatin, lanreotide
is an inhibitor of various endocrine, neuroendocrine, exocrine, and paracrine
functions.
The primary pharmacodynamic effect of lanreotide is a
reduction of GH and/or IGF-1 levels enabling normalization of levels in
acromegalic patients [see Clinical Studies]. In acromegalic patients,
lanreotide reduces GH levels in a dose-dependent way. After a single injection
of SOMATULINE DEPOT, plasma GH levels fall rapidly and are maintained for at
least 28 days.
Lanreotide inhibits the basal secretion of motilin,
gastric inhibitory peptide, and pancreatic polypeptide, but has no significant
effect on the secretion of secretin. Lanreotide inhibits postprandial secretion
of pancreatic polypeptide, gastrin, and cholecystokinin (CCK). In healthy
subjects, lanreotide produces a reduction and a delay in postprandial insulin
secretion, resulting in transient, mild glucose intolerance.
Lanreotide inhibits meal-stimulated pancreatic
secretions, and reduces duodenal bicarbonate and amylase concentrations, and
produces a transient reduction in gastric acidity.
Lanreotide has been shown to inhibit gallbladder
contractility and bile secretion in healthy subjects [see WARNINGS AND
PRECAUTIONS].
In healthy subjects, lanreotide inhibits meal-induced
increases in superior mesenteric artery and portal venous blood flow, but has
no effect on basal or meal-stimulated renal blood flow. Lanreotide has no
effect on renal plasma flow or renal vascular resistance. However, a transient
decrease in glomerular filtration rate (GFR) and filtration fraction has been
observed after a single injection of lanreotide.
In healthy subjects, non-significant reductions in
glucagon levels were seen after lanreotide administration. In diabetic
non-acromegalic subjects receiving a continuous infusion (21-day) of
lanreotide, serum glucose concentrations were temporarily decreased by 20-30%
after the start and end of the infusion. Serum glucose concentrations returned
to normal levels within 24 hours. A significant decrease in insulin
concentrations was recorded between baseline and Day 1 only [see WARNINGS
AND PRECAUTIONS].
Lanreotide inhibits the nocturnal increase in
thyroid-stimulating hormone (TSH) seen in healthy subjects. Lanreotide reduces
prolactin levels in acromegalic patients treated on a long-term basis.
Pharmacokinetics
SOMATULINE DEPOT is thought to form a drug depot at the
injection site due to the interaction of the formulation with physiological
fluids. The most likely mechanism of drug release is a passive diffusion of the
precipitated drug from the depot towards the surrounding tissues, followed by the
absorption to the bloodstream.
After a single, deep subcutaneous administration, the
mean absolute bioavailability of SOMATULINE DEPOT in healthy subjects was 73.4,
69.0, and 78.4% for the 60 mg, 90 mg, and 120 mg doses, respectively. Mean C max
values ranged from 4.3 to 8.4 ng/mL during the first day. Single-dose linearity
was demonstrated with respect to AUC and Cmax , and showed high inter-subject
variability. SOMATULINE DEPOT showed sustained release of lanreotide with a
half-life of 23 to 30 days. Mean serum concentrations were > 1 ng/mL
throughout 28 days at 90 mg and 120 mg and > 0.9 ng/mL at 60 mg.
In studies evaluating excretion, < 5% of lanreotide was
excreted in urine and less than 0.5% was recovered unchanged in feces,
indicative of some biliary excretion.
Acromegaly
In a repeat-dose administration pharmacokinetics (PK)
study in acromegalic patients, rapid initial release was seen giving peak
levels during the first day after administration. At doses of SOMATULINE DEPOT
between 60 and 120 mg, linear pharmacokinetics were observed in acromegalic
patients. At steady state, mean C max values were 3.8 ± 0.5, 5.7 ± 1.7, and 7.7
± 2.5 ng/mL, increasing linearly with dose. The mean accumulation ratio index
was 2.7, which is in line with the range of values for the half-life of
SOMATULINE DEPOT. The steady-state trough serum lanreotide concentrations in
patients receiving SOMATULINE DEPOT every 28 days were 1.8 ± 0.3; 2.5 ± 0.9 and
3.8 ± 1.0 ng/mL at 60 mg, 90 mg, and 120 mg doses, respectively. A limited
initial burst effect and a low peak-to-trough fluctuation (81% to 108%) of the
serum concentration at the plateau were observed.
For the same doses, similar values were obtained in
clinical studies after at least four administrations (2.3 ± 0.9, 3.2 ± 1.1, and
4.0 ± 1.4 ng/mL, respectively).
Pharmacokinetic data from studies evaluating extended
dosing use of SOMATULINE DEPOT 120 mg demonstrated mean steady-state, C min values
between 1.6 and 2.3 ng/mL for the 8-and 6-week treatment interval,
respectively.
Gastroenteropancreatic Neuroendocrine Tumors
In patients with GEP-NETs treated with SOMATULINE DEPOT
120 mg every 4 weeks, steady state concentrations were reached after 4 to 5
injections and the mean trough serum lanreotide concentrations at steady state
ranged from 5.3 to 8.6 ng/mL.
Specific Populations
SOMATULINE DEPOT has not been studied in specific populations.
However, the pharmacokinetics of lanreotide in renal impaired, hepatic
impaired, and geriatric subjects were evaluated after IV administration of
lanreotide immediate release formulation (IRF) at 7 mcg/kg dose.
Geriatric
Studies in healthy elderly subjects showed an 85%
increase in half-life and a 65% increase in mean residence time (MRT) of
lanreotide compared to those seen in healthy young subjects; however, there was
no change in either AUC or Cmax of lanreotide in elderly as compared to healthy
young subjects. Age has no effect on clearance of lanreotide based on
population PK analysis in patients with GEP-NET which included 122 patients
aged 65 to 85 years with neuroendocrine tumors.
Renal Impairment
An approximate 2-fold decrease in total serum clearance
of lanreotide, with a consequent 2-fold increase in half-life and AUC was
observed. Patients with acromegaly and with moderate to severe renal impairment
should begin treatment with SOMATULINE DEPOT 60 mg. Caution should be exercised
when considering patients with moderate or severe renal impairment for an
extended dosing interval of SOMATULINE DEPOT 120 mg every 6 or 8 weeks.
Mild (CLcr 60-89 mL/min) or moderate (CLcr 30-59 mL/min)
renal impairment has no effect on clearance of lanreotide in patients with
GEP-NET based on population PK analysis which included 106 patients with mild
and 59 patients with moderate renal impairment treated with SOMATULINE DEPOT.
GEP-NET patients with severe renal impairment (CLcr < 30 mL/min) were not
studied.
Hepatic Impairment
In subjects with moderate to severe hepatic impairment, a
30% reduction in clearance of lanreotide was observed. Patients with acromegaly
and with moderate to severe hepatic impairment should begin treatment with
SOMATULINE DEPOT 60 mg. Caution should be exercised when considering patients
with moderate or severe hepatic impairment for an extended dosing interval of
SOMATULINE DEPOT 120 mg every 6 or 8 weeks.
The effect of hepatic impairment on clearance of lanreotide
has not been studied in patients with GEP-NET.
Clinical Studies
Acromegaly
The effect of SOMATULINE DEPOT on reducing GH and
IGF-levels and control of symptoms in patients with acromegaly was studied in
two long-term, multiple-dose, randomized, multicenter studies.
Study 1
This one-year study included a 4-week, double-blind,
placebo-controlled phase; a 16-week single-blind, fixed-dose phase; and a
32-week, open-label, dose-titration phase. Patients with active acromegaly,
based on biochemical tests and medical history, entered a 12-week washout
period if there was previous treatment with a somatostatin analog or a
dopaminergic agonist.
Upon entry, patients were randomly allocated to receive a
single, deep subcutaneous injection of SOMATULINE DEPOT 60 mg, 90 mg, or 120 mg
or placebo. Four weeks later, patients entered a fixed-dose phase where they
received 4 injections of SOMATULINE DEPOT followed by a dose-titration phase of
8 injections for a total of 13 injections over 52 weeks (including the placebo
phase). Injections were given at 4-week intervals. During the dose-titration
phase of the study, the dose was titrated twice (every fourth injection), as
needed, according to individual GH and IGF-1 levels.
A total of 108 patients (51 males, 57 females) were
enrolled in the initial placebo-controlled phase of the study. Half (54/108) of
the patients had never been treated with a somatostatin analog or dopamine
agonist, or had stopped treatment for at least 3 months prior to their
participation in the study and were required to have a mean GH level > 5
ng/mL at their first visit. The other half of the patients had received prior
treatment with a somatostatin analog or a dopamine agonist before study entry
and at study entry were required to have a mean GH concentration > 3 ng/mL and
at least a 100% increase in mean GH concentration after washout of medication.
One hundred and seven (107) patients completed the
placebo-controlled phase, 105 patients completed the fixed-dose phase, and 99
patients completed the dose-titration phase. Patients not completing withdrew
due to adverse events (5) or lack of efficacy (4).
In the double-blind phase of study 1, a total of 52 (63%)
of the 83 lanreotide-treated patients had a > 50% decrease in mean GH from
baseline to Week 4, including 52%, 44%, and 90% of patients in the 60 mg, 90
mg, and 120 mg groups, respectively, compared to placebo (0%, 0/25). In the
fixed-dose phase at Week 16, 72% of all 107 lanreotide-treated patients had a
decrease from baseline in mean GH of > 50%, including 68% (23/34), 64%
(23/36), and 84% (31/37) of patients in the 60 mg, 90 mg, and 120 mg lanreotide
treatment groups, respectively. Efficacy achieved in the first 16 weeks was
maintained for the duration of the study (see Table 4).
Table 4: Overall Efficacy Results Based on GH and
IGF-1 Levels by Treatment Phase in Study 1
|
|
Baseline
N=107 |
Before Titration 1 (16 weeks)
N=107 |
Before Titration 2 (32 weeks)
N=105 |
Last Value Available*
N=107 |
GH |
≤ 5.0 ng/mL |
Number of Responders (%) |
20 (19%) |
72 (67%) |
76 (72%) |
74 (69%) |
≤ 2.5 ng/mL |
Number of Responders (%) |
0 (0%) |
52 (49%) |
59 (56%) |
55 (51%) |
≤ 1.0 ng/mL |
Number of Responders (%) |
0 (0%) |
15 (14%) |
18 (17%) |
17 (16%) |
Median GH |
ng/mL |
10.27 |
2.53 |
2.20 |
2.43 |
GH Reduction |
Median % Reduction |
-- |
75.5 |
78.2 |
75.5 |
IGF-1 |
Normal3 |
Number of |
9 |
58 |
57 |
62 |
|
Responders (%) |
(8%) |
(54%) |
(54%) |
(58%) |
Median IGF-1 |
ng/mL |
775.0 |
332.01 |
316.52 |
326.0 |
IGF-1 Reduction |
Median % Reduction |
-- |
52.31 |
54.52 |
55.4 |
IGF-1 Normal3 +GH ≤ 2.5 ng/mL |
Number of Responders (%) |
0 (0%) |
41 (38%) |
46 (44%) |
44 (41%) |
1n=105,
2n=102,
3Age-adjusted,
*Last Observation Carried Forward |
Study 2
This was a 48-week, open-label,
uncontrolled, multicenter study that enrolled patients who had an IGF-1
concentration ≥ 1.3 times the upper limit of the normal age-adjusted
range. Patients receiving treatment with a somatostatin analog (other than
SOMATULINE DEPOT) or a dopaminergic agonist had to attain this IGF1
concentration after a washout period of up to 3 months.
Patients were initially
enrolled in a 4-month, fixed-dose phase where they received 4 deep subcutaneous
injections of SOMATULINE DEPOT 90 mg, at 4-week intervals. Patients then
entered a dose-titration phase where the dose of SOMATULINE DEPOT was adjusted
based on GH and IGF-1 levels at the beginning of the dose-titration phase and,
if necessary, again after another 4 injections. Patients titrated up to the
maximum dose (120 mg) were not allowed to titrate down again.
A total of 63 patients (38
males, 25 females) entered the fixed-dose phase of the trial and 57 patients
completed 48 weeks of treatment. Six patients withdrew due to adverse reactions
(3), other reasons (2), or lack of efficacy (1).
After 48 weeks of treatment
with SOMATULINE DEPOT at 4-week intervals, 43% (27/63) of the acromegalic
patients in this study achieved normal age-adjusted IGF-1 concentrations. Mean
IGF-1 concentrations after treatment completion were 1.3 ± 0.7 times the upper
limit of normal compared to 2.5 ± 1.1 times the upper limit of normal at
baseline.
The reduction in IGF-1
concentrations over time correlated with a corresponding marked decrease in
mean GH concentrations. The proportion of patients with mean GH concentrations
< 2.5 ng/mL increased significantly from 35% to 77% after the fixed-dose
phase and 85% at the end of the study. At the end of treatment, 24/63 (38%) of
patients had both normal IGF-1 concentrations and a GH concentration of ≤
2.5 ng/mL (see Table 5) and 17/63 patients (27%) had both normal IGF-1
concentrations and a GH concentration of < 1 ng/mL.
Table 5: Overall Efficacy Results Based on GH and
IGF-1 Levels by Treatment Phase in Study 2
|
|
Baseline
N=63 |
Before Titration 1(12 wks)
N=63 |
Before Titration 2(28 wks)
N=59 |
Last Value Available*
N=63 |
IGF-1 |
Normal1 |
Number of Responders (%) |
0(0%) |
17(27%) |
22(37%) |
27(43%) |
Median IGF-1 |
ng/mL |
689.0 |
382.0 |
334.0 |
317.0 |
IGF-1 Reduction |
Median % Reduction |
-- |
41.0 |
51.0 |
50.3 |
GH |
≤ 5.0 ng/mL |
Number of Responders (%) |
40 (64%) |
59 (94%) |
57 (97%) |
62 (98%) |
≤ 2.5 ng/mL |
Number of Responders (%) |
21 (33%) |
47 (75%) |
47 (80%) |
54 (86 %) |
≤ 1.0 ng/mL |
Number of Responders (%) |
8 (13%) |
19 (30%) |
18 (31%) |
28 (44%) |
Median GH |
ng/mL |
3.71 |
1.65 |
1.48 |
1.13 |
GH Reduction |
Median % Reduction |
-- |
63.2 |
66.7 |
78.62 |
IGF-1 normal1 +GH ≤ 2.5 ng/mL |
Number of Responders (%) |
0 (0%) |
14 (22%) |
20 (34%) |
24 (38%) |
1Age-adjusted,
2N= 62,
*Last Observation Carried Forward |
Examination of age and gender
subgroups did not identify differences in response to SOMATULINE DEPOT among
these subgroups. The limited number of patients in the different racial
subgroups did not raise any concerns regarding efficacy of SOMATULINE DEPOT in
these subgroups.
Gastroenteropancreatic
Neuroendocrine Tumors
The efficacy of SOMATULINE
DEPOT was established in a multicenter, randomized, double-blind,
placebo-controlled trial of 204 patients with unresectable, well or moderately
differentiated, metastatic or locally advanced, gastroenteropancreatic
neuroendocrine tumors. Patients were required to have non-functioning tumors
without hormone-related symptoms. Patients were randomized 1:1 to receive
SOMATULINE DEPOT 120 mg (n=101) or placebo (n=103) every 4 weeks until disease
progression, unacceptable toxicity or a maximum of 96 weeks of treatment.
Randomization was stratified by the presence or absence of prior therapy and by
the presence or absence of disease progression within 6 months of enrollment.
The major efficacy outcome measure was progression-free survival (PFS), defined
as time to disease progression as assessed by central independent radiological
review using the Response Evaluation Criteria in Solid Tumors (RECIST 1.0), or
death.
The median patient age was 63
years (range 30-92 years) and 95% were Caucasian. Disease progression was
present in nine of 204 patients (4.4%) in the 6 months prior to enrollment and
twenty-nine patients (14%) received prior chemotherapy. Ninety-one patients
(45%) had primary sites of disease in the pancreas, with the remainder
originating in the midgut (35%), hindgut (7%), or unknown primary location
(13%). The majority (69%) of the study population had grade 1 tumors. Baseline
prognostic characteristics were similar between arms with one exception; there
were 39% of patients in the SOMATULINE DEPOT arm and 27% of patients in the
placebo arm who had hepatic involvement by tumor of > 25%.
Patients on the SOMATULINE DEPOT arm had a statistically
significant improvement in progression-free survival compared to patients
receiving placebo (see Table 6 and Figure 1).
Table 6: Efficacy Results in Study 3
|
SOMATULINE DEPOT
n = 101 |
Placebo
n = 103 |
Number of Events (%) |
32 (31.7%) |
60 (58.3%) |
Median PFS (months)(95% CI) |
NE1 (NE, NE) |
16.6 (11.2, 22.1) |
HR (95% CI) |
0.47 (0.30, 0.73)2 |
Log-rank p-value |
< 0.001 |
1 NE = not reached at 22 months
2 Hazard Ratio is derived from a Cox stratified proportional hazards
model |
Figure 1: Kaplan-Meier
Curves of Progression-Free Survival