CLINICAL PHARMACOLOGY
Mechanism Of Action
EVENITY inhibits the action of
sclerostin, a regulatory factor in bone metabolism. EVENITY increases bone
formation and, to a lesser extent, decreases bone resorption. Animal studies
showed that romosozumab-aqqg stimulates new bone formation on trabecular and
cortical bone surfaces by stimulating osteoblastic activity resulting in
increases in trabecular and cortical bone mass and improvements in bone
structure and strength [see Nonclinical Toxicology and Clinical
Studies].
Pharmacodynamics
In postmenopausal women with
osteoporosis, EVENITY increased the bone formation marker procollagen type 1
N-telopeptide (P1NP) with a peak increase from baseline of approximately 145%
compared to placebo 2 weeks after initiating treatment, followed by a return to
concentrations seen with placebo at month 9 and a decline from baseline to
approximately 15% below the concentration change seen with placebo at month 12.
EVENITY decreased the bone resorption marker type 1
collagen C-telopeptide (CTX) with a maximal reduction from baseline of approximately
55% compared to placebo 2 weeks after initiating treatment. CTX remained below
concentrations seen with placebo and was approximately 25% below the
concentration change seen with placebo at month 12.
After discontinuation of EVENITY, P1NP levels returned to
baseline within 12 months; CTX increased above baseline levels within 3 months
and returned toward baseline levels by month 12.
Pharmacokinetics
Administration of a single dose of 210 mg EVENITY in
healthy volunteers resulted in a mean (standard deviation [SD]) maximum
romosozumab-aqqg serum concentration (Cmax) of 22.2 (5.8) mcg/mL and a mean
(SD) AUC of 389 (127) mcg*day/mL. Steady-state concentrations were achieved by
month 3 following the monthly administration of 210 mg to postmenopausal women.
The mean trough serum romosozumab-aqqg concentrations at months 3, 6, 9, and 12
ranged from 8 to 13 mcg/mL.
Romosozumab-aqqg exhibited nonlinear pharmacokinetics
with exposure increasing greater than dose proportionally (e.g., 550-fold
increase in mean AUCinf for the 100-fold increase in subcutaneous doses ranging
from 0.1 to 10 mg/kg [0.03 to 3.3 times the approved recommended dosage for a
70 kg woman).
Absorption
The median time to maximum romosozumab-aqqg concentration
(Tmax) is 5 days (range: 2 to 7 days).
Distribution
The estimated volume of distribution at steady-state is
approximately 3.92 L.
Elimination
Romosozumab-aqqg exhibited nonlinear pharmacokinetics
with the clearance of romosozumab-aqqg decreasing as the dose increased. The
estimated mean systemic clearance (CL/F) of romosozumab-aqqg was 0.38 mL/hr/kg,
following a single subcutaneous administration of 3 mg/kg (the approved
recommended dosage for a 70 kg woman). The mean effective t½ was 12.8 days
after 3 doses of 3 mg/kg (the approved recommended dosage for a 70 kg woman)
every 4 weeks.
Metabolism
The metabolic pathway of romosozumab-aqqg has not been
characterized. As a humanized IgG2 monoclonal antibody, romosozumab-aqqg is
expected to be degraded into small peptides and amino acids via catabolic
pathways in a manner similar to endogenous IgG.
Anti-Product Antibody Formation Affecting Pharmacokinetics
Development of anti-romosozumab-aqqg antibodies was
associated with reduced serum romosozumabaqqg concentrations. The presence of
anti-romosozumab-aqqg antibodies led to decreased mean romosozumab-aqqg
concentrations up to 22%. The presence of neutralizing antibodies led to
decreased mean romosozumab-aqqg concentrations up to 63% [see ADVERSE
REACTIONS].
Specific Populations
No clinically significant differences in the pharmacokinetics
of romosozumab-aqqg were observed based on age (20-89 years), sex, race,
disease state (low bone mass or osteoporosis), prior exposure to alendronate,
or renal impairment including end-stage renal disease (ESRD) requiring
dialysis. The effect of ESRD not requiring dialysis on the pharmacokinetics of
romosozumab-aqqg is unknown.
Body Weight
The exposure of romosozumab-aqqg decreases with
increasing body weight.
Animal Toxicology And Pharmacology
No adverse effects were noted in rats and monkeys after
26 once-weekly subcutaneous romosozumab-aqqg doses up to 100 mg/kg, equivalent
to systemic exposures of 38 and 93 times, respectively, the systemic exposure
observed in humans following a monthly subcutaneous dose of 210 mg EVENITY
(based on AUC comparison).
Bone safety studies of up to 12-month duration were
conducted in ovariectomized rats and monkeys with once-weekly romosozumab-aqqg
doses yielding exposures ranging from 1 to 22 times the systemic exposure in
humans given monthly doses of 210 mg, based on AUC comparison. Romosozumab-aqqg
increased bone mass and improved cancellous bone microarchitecture and cortical
bone geometry by increasing bone formation on periosteal, endocortical, and
trabecular surfaces, and decreasing bone resorption on trabecular and
endocortical surfaces. The increases in bone mass were significantly correlated
with increases in bone strength. In rats and monkeys, bone quality was
maintained at all skeletal sites at doses ranging from 1 to 22 times human
exposure, and slightly improved in vertebrae at 19 to 22 times human exposure.
There was no evidence of mineralization defects, osteoid accumulation, or woven
bone formation.
Clinical Studies
Treatment Of Osteoporosis In Postmenopausal Women
Study 1 (NCT01575834) was a randomized, double-blind,
placebo-controlled study of postmenopausal women aged 55 to 90 years (mean age
of 71 years) with bone mineral density (BMD) T-score less than or equal to -2.5
at the total hip or femoral neck. Women were randomized to receive subcutaneous
injections of either EVENITY (N = 3589) or placebo (N = 3591) for 12 months. At
baseline, 18% of women had a vertebral fracture. After the 12-month treatment
period, women in both arms transitioned to open-label anti-resorptive therapy
(denosumab) for 12 months while remaining blinded to their initial treatment.
Women received 500 to 1000 mg calcium and 600 to 800 international units
vitamin D supplementation daily. The coprimary efficacy endpoints were new
vertebral fracture at month 12 and month 24.
Effect On Fractures
EVENITY significantly reduced the incidence of new
vertebral fractures through month 12 compared to placebo. In addition, the
significant reduction in fracture risk persisted through the second year in
women who received EVENITY during the first year and transitioned to denosumab
compared to those who transitioned from placebo to denosumab (see Table 2).
Table 2 : Effect of EVENITY on the Incidence and Risk
of Fractures in Study 1
|
Proportion of Women with Fractures |
Absolute Risk Reduction (%) (95% CI)a |
Relative Risk Reduction (%) (95% CI)a |
p-valueb |
At Month 12 |
Placebo
(N = 3591) |
EVENITY
(N = 3589) |
|
|
|
New vertebral fracture |
1.8% |
0.5% |
1.3
(0.8, 1.8) |
73
(53, 84) |
< 0.001 |
At Month 24 |
Placebo Followed by Denosumab
(N = 3591) |
EVENITY Followed by Denosumab
(N = 3589) |
|
|
|
New vertebral fracture |
2.5% |
0.6% |
1.9
(1.3, 2.5) |
75
(60, 84) |
< 0.001 |
N = Number of subjects randomized
a Absolute
and relative risk reduction are based on the Mantel-Haenszel method adjusting
for age and prevalent vertebral fracture strata.
b P-value
is based on logistic regression model adjusting for age and prevalent vertebral
fracture strata. |
EVENITY significantly reduced
the incidence of clinical fracture (a composite endpoint of symptomatic
vertebral fracture and nonvertebral fracture) at 12 months. However, 88% of
these clinical fractures were nonvertebral fractures and the incidence of
nonvertebral fractures was not statistically significantly different when
comparing EVENITY-treated women to placebo-treated women at month 12 or month
24.
Effect On BMD
EVENITY significantly increased
BMD at the lumbar spine, total hip, and femoral neck compared with placebo at
month 12. The treatment differences in BMD were 12.7% at the lumbar spine, 5.8%
at the total hip, and 5.2% at the femoral neck.
Following the transition from
EVENITY to denosumab at month 12, BMD continued to increase through month 24.
In patients who transitioned from placebo to denosumab, BMD also increased with
denosumab use. The differences in BMD achieved at month 12 between EVENITY and
placebo patients were overall maintained at month 24, when comparing patients
who transitioned from EVENITY to denosumab to those who transitioned from
placebo to denosumab. There was no evidence of differences in effects on BMD at
the lumbar spine or total hip across subgroups defined by baseline age,
baseline BMD, or geographic region.
After EVENITY discontinuation,
BMD returns to approximately baseline levels within 12 months in the absence of
follow-on antiresorptive therapy [see INDICATIONS AND USAGE].
Bone Histology And Histomorphometry
A total of 154 transiliac crest
bone biopsy specimens were obtained from 139 postmenopausal women with
osteoporosis at month 2, month 12, and/or month 24. All of these biopsies were
adequate for qualitative histology and 138 (90%) were adequate for full
quantitative histomorphometry assessment. Qualitative histology assessments
from women treated with EVENITY showed normal bone architecture and quality at
all time points. There was no evidence of woven bone, mineralization defects,
or marrow fibrosis.
Histomorphometry assessments on
biopsies at months 2 and 12 compared the effect of EVENITY with placebo (15
specimens at month 2 and 39 specimens at month 12 in the EVENITY group, 14
specimens at month 2 and 31 specimens at month 12 in the placebo group). At
month 2 in women treated with EVENITY, histomorphometric indices of bone
formation at trabecular and endocortical surfaces were increased. These effects
on bone formation were accompanied by a decrease in indices of bone resorption.
At month 12, both bone formation and resorption indices were decreased with
EVENITY, while bone volume, and trabecular and cortical thickness were
increased.
Study 2 (NCT01631214) was a
randomized, double-blind, alendronate-controlled study of postmenopausal women
aged 55 to 90 years (mean age of 74 years) with BMD T-score less than or equal
to -2.5 at the total hip or femoral neck and either one moderate or
severe vertebral fracture or two mild vertebral fractures, or BMD T-score less
than or equal to -2.0 at the total hip or femoral neck and either two moderate
or severe vertebral fractures or a history of a proximal femur fracture. Women
were randomized (1:1) to receive either monthly subcutaneous injections of
EVENITY (N = 2046) or oral alendronate 70 mg weekly (N = 2047) for 12 months,
with 500 to 1000 mg calcium and 600 to 800 international units vitamin D
supplementation daily. After the 12-month treatment period, women in both arms
transitioned to open-label alendronate 70 mg weekly while remaining blinded to
their initial treatment.
This was an event driven trial.
The coprimary efficacy endpoints were the incidence of morphometric vertebral
fracture at 24 months and time to the first clinical fracture through the
primary analysis period, which ended when at least 330 subjects had a clinical
fracture and all subjects had completed the 24-month visit. Clinical fracture
was a composite endpoint of nonvertebral fracture and symptomatic vertebral
fracture.
Effect On Fractures
EVENITY significantly reduced the incidence of new
vertebral fracture at 24 months (see Table 3).
Table 3 : Effect of EVENITY on the Incidence of New
Vertebral Fractures in Study 2
|
Proportion of Women with F racture (%) |
Risk Reduction |
p-value b |
Alendronate Alone
(N = 2047) |
EVENITY Followed by Alendronate
(N = 2046) |
Absolute Risk Reduction (%) (95% CI)a |
Relative Risk Reduction (%) (95% CI)a |
New vertebral fracture through Month 24 |
8.0% |
4.1% |
4.0
(2.5, 5.6) |
50
(34, 62) |
<0.001 |
N= Number of subjects
randomized
a Absolute and relative risk reductions are based on the
Mantel-Haenszel method adjusting for age strata, baseline total hip BMD T-score
(≤ -2.5, > -2.5), and presence of severe vertebral fracture at
baseline.
b P-value is based on logistic regression model for new vertebral
fracture) adjusting for age strata, baseline total hip BMD T-score, and
presence of severe vertebral fracture at baseline. |
EVENITY significantly reduced
the risk of clinical fracture through the end of the primary analysis period
(see Table 4). This was an event-driven trial and the duration of follow-up
varied across subjects. The median duration of subject follow-up for the
primary analysis period was 33 months. Subjects with nonvertebral fracture
comprised 83% of the subjects with clinical fracture during the primary
analysis period.
Table 4 : Effect of EVENITY
on the Risk of Clinical Fractures in Study 2
|
Proportion of Women with F racture (%)a |
Hazard Ratio (95% CI)c |
p-valuec |
Alendronate Alone
(N = 2047) |
EVENITY Followed by Alendronate
(N = 2046) |
Clinical fracture through primary analysis periodb |
13.0% |
9.7% |
0.73
(0.61, 0.88) |
<0.001 |
N= Number of subjects randomized
a %
= number of subjects who had a clinical fracture through the primary analysis
period/N*100%; the duration of follow-up varied across subjects.
b Primary analysis period ended when clinical fracture events were
confirmed for at least 330 subjects and all subjects completed the month 24
study visit. The median duration of follow-up for the primary analysis period
was 33 months.
cHazard ratio and P-value are based on Cox
proportional hazards model adjusting for age strata, baseline total hip BMD
T-score, and presence of severe vertebral fracture at baseline |
EVENITY followed by alendronate
also significantly reduced the risk of nonvertebral fracture through the
primary analysis period (with a median follow-up of 33 months), with a hazard
ratio of 0.81 (95% CI: 0.66, 0.99; p = 0.04) compared to alendronate alone.
Effect On Bone Mineral Density (BMD)
EVENITY significantly increased BMD at the lumbar spine,
total hip, and femoral neck compared with alendronate at month 12. The
treatment differences in BMD were 8.7% at the lumbar spine, 3.3% at the total
hip, and 3.2% at the femoral neck.
Twelve months of treatment with EVENITY followed by 12
months of treatment with alendronate significantly increased BMD compared with
alendronate alone. The BMD increase with EVENITY over alendronate observed at
month 12 was maintained at month 24. The treatment differences in BMD at month
24 were 8.1% at the lumbar spine, 3.8% at the total hip, and 3.8% at the
femoral neck.
There was no evidence of differences in effects on BMD at
the lumbar spine or total hip across subgroups defined by baseline age,
baseline BMD, or geographic region.