Clinical Pharmacology for Osenvelt
Mechanism Of Action
Denosumab products bind to RANKL, a transmembrane or
soluble protein essential for the formation, function, and survival of
osteoclasts, the cells responsible for bone resorption, thereby modulating
calcium release from bone. Increased osteoclast activity, stimulated by RANKL,
is a mediator of bone pathology in solid tumors with osseous metastases.
Similarly, giant cell tumors of bone consist of stromal cells expressing RANKL
and osteoclast-like giant cells expressing RANK receptor, and signaling through
the RANK receptor contributes to osteolysis and tumor growth. Denosumab
products prevent RANKL from activating its receptor, RANK, on the surface of
osteoclasts, their precursors, and osteoclast-like giant cells.
Pharmacodynamics
In patients with breast cancer and bone metastases, the median
reduction in uNTx/Cr was 82% within 1 week following initiation of denosumab
120 mg administered subcutaneously. In Studies 20050136, 20050244, and
20050103, the median reduction in uNTx/Cr from baseline to Month 3 was
approximately 80% in 2075 denosumab-treated patients.
In a phase 3 study of patients with newly diagnosed
multiple myeloma who received subcutaneous doses of denosumab 120 mg every 4
weeks (Q4W), median reductions in uNTx/Cr of approximately 75% were observed by
week 5. Reductions in bone turnover markers were maintained, with median
reductions of 74% to 79% for uNTx/Cr from weeks 9 to 49 of continued 120 mg Q4W
dosing.
In adult and skeletally mature adolescent patients with
giant cell tumor of bone who received subcutaneous doses of denosumab 120 mg
Q4W with a 120 mg loading dose on Days 8 and 15, median reductions in uNTx/Cr
from baseline were 84% at Week 13 and 82% at Week 25.
Pharmacokinetics
Following subcutaneous administration, bioavailability
was 62%. Denosumab displayed nonlinear pharmacokinetics at doses below 60 mg,
but approximately dose-proportional increases in exposure at higher doses.
With multiple subcutaneous doses of 120 mg once every 4
weeks, up to 2.8-fold accumulation in serum denosumab concentrations was observed
and steady-state was achieved by 6 months. A mean (± standard deviation) serum
steady-state trough concentration of 20.5 (± 13.5) mcg/mL was achieved by 6
months. The mean elimination half-life was 28 days.
In patients with newly diagnosed multiple myeloma who
received 120 mg every 4 weeks, denosumab concentrations appear to reach
steady-state by month 6. In patients with giant cell tumor of bone, after
administration of subcutaneous doses of 120 mg once every 4 weeks with
additional 120 mg doses on Days 8 and 15 of the first month of therapy, mean (±
standard deviation) serum trough concentrations on Day 8, 15, and one month
after the first dose were 19.0 (± 24.1), 31.6 (± 27.3), 36.4 (± 20.6) mcg/mL,
respectively. Steady-state was achieved in 3 months after initiation of
treatment with a mean serum trough concentration of 23.4 (± 12.1) mcg/mL.
Special Populations
Body Weight
A population pharmacokinetic analysis was performed to
evaluate the effects of demographic characteristics. Denosumab clearance and
volume of distribution were proportional to body weight. The steady-state
exposure following repeat subcutaneous administration of 120 mg every 4 weeks
to 45 kg and 120 kg subjects were, respectively, 48% higher and 46% lower than
exposure of the typical 66 kg subject.
Age, Gender And Race
The pharmacokinetics of denosumab was not affected by
age, gender, and race.
Pediatrics
In skeletally-mature adolescent patients (12 to 16 years
of age) with giant cell tumor of bone (GCTB) who received 120 mg every 4 weeks
with a 120 mg loading dose on Days 8 and 15, the pharmacokinetics of denosumab
were comparable to those observed in adult patients with GCTB.
Hepatic Impairment
No clinical trials have been conducted to evaluate the
effect of hepatic impairment on the pharmacokinetics of denosumab products.
Renal Impairment
In clinical trials of 87 patients with varying degrees
of renal dysfunction, including patients on dialysis, the degree of renal
impairment had no effect on the pharmacokinetics and pharmacodynamics of
denosumab [see Use In Specific Populations].
Drug Interactions
No formal drug-drug interaction trials have been
conducted with denosumab. There was no evidence that various anticancer
treatments affected denosumab systemic exposure and pharmacodynamic effect.
Serum denosumab concentrations at 1 and 3 months and reductions in the bone
turnover marker uNTx/Cr (urinary N-terminal telopeptide corrected for
creatinine) at 3 months were similar in patients with and without prior
intravenous bisphosphonate therapy and were not altered by concomitant chemotherapy
and/or hormone therapy.
Animal Toxicology And/Or Pharmacology
Denosumab products are inhibitors of osteoclastic bone resorption
via inhibition of RANKL.
Because the biological activity of denosumab in animals
is specific to nonhuman primates, evaluation of genetically engineered
(knockout) mice or use of other biological inhibitors of the RANK/RANKL
pathway, OPG-Fc and RANK-Fc, provided additional information on the
pharmacodynamic properties of denosumab. RANK/RANKL knockout mice exhibited
absence of lymph node formation, as well as an absence of lactation due to
inhibition of mammary gland maturation (lobulo-alveolar gland development
during pregnancy). Neonatal RANK/RANKL knockout mice exhibited reduced bone
growth and lack of tooth eruption. A corroborative study in 2-week-old rats
given the RANKL inhibitor OPG-Fc also showed reduced bone growth, altered
growth plates, and impaired tooth eruption. These changes were partially
reversible in this model when dosing with the RANKL inhibitors was
discontinued.
Clinical Trials
Bone Metastasis From Solid Tumors
The safety and efficacy of denosumab for the prevention
of skeletal-related events in patients with bone metastases from solid tumors
was demonstrated in three international, randomized (1:1), double-blind,
active-controlled, noninferiority trials comparing denosumab with zoledronic
acid. In all three trials, patients were randomized to receive 120 mg denosumab
subcutaneously every 4 weeks or 4 mg zoledronic acid intravenously (IV) every 4
weeks (dose adjusted for reduced renal function). Patients with creatinine
clearance less than 30 mL/min were excluded. In each trial, the main outcome
measure was demonstration of noninferiority of time to first skeletal-related
event (SRE) as compared to zoledronic acid. Supportive outcome measures were
superiority of time to first SRE and superiority of time to first and subsequent
SRE; testing for these outcome measures occurred if the main outcome measure
was statistically significant. An SRE was defined as any of the following:
pathologic fracture, radiation therapy to bone, surgery to bone, or spinal cord
compression.
Study 20050136 (NCT00321464) enrolled 2046 patients with
advanced breast cancer and bone metastasis. Randomization was stratified by a
history of prior SRE (yes or no), receipt of chemotherapy within 6 weeks prior
to randomization (yes or no), prior oral bisphosphonate use (yes or no), and
region (Japan or other countries). Forty percent of patients had a previous
SRE, 40% received chemotherapy within 6 weeks prior to randomization, 5%
received prior oral bisphosphonates, and 7% were enrolled from Japan. Median
age was 57 years, 80% of patients were White, and 99% of patients were women.
The median number of doses administered was 18 for denosumab and 17 for
zoledronic acid.
Study 20050244 (NCT00330759) enrolled 1776 adults with
solid tumors other than breast and castrate-resistant prostate cancer with bone
metastasis and multiple myeloma. Randomization was stratified by previous SRE
(yes or no), systemic anticancer therapy at time of randomization (yes or no),
and tumor type (non-small cell lung cancer, myeloma, or other). Eighty-seven
percent were receiving systemic anticancer therapy at the time of
randomization, 52% had a previous SRE, 64% of patients were men, 87% were
White, and the median age was 60 years. A total of 40% of patients had
non-small cell lung cancer, 10% had multiple myeloma, 9% had renal cell
carcinoma, and 6% had small cell lung cancer. Other tumor types each comprised
less than 5% of the enrolled population. The median number of doses
administered was 7 for both denosumab and zoledronic acid.
Study 20050103 (NCT00321620) enrolled 1901 men with
castrate-resistant prostate cancer and bone metastasis. Randomization was
stratified by previous SRE, PSA level (less than 10 ng/mL or 10 ng/mL or
greater) and receipt of chemotherapy within 6 weeks prior to randomization (yes
or no). Twenty-six percent of patients had a previous SRE, 15% of patients had
PSA less than 10 ng/mL, and 14% received chemotherapy within 6 weeks prior to
randomization. Median age was 71 years and 86% of patients were White. The
median number of doses administered was 13 for denosumab and 11 for zoledronic
acid.
Denosumab delayed the time to first SRE following
randomization as compared to zoledronic acid in patients with breast or
castrate-resistant prostate cancer (CRPC) with osseous metastases (Table 2). In
patients with bone metastasis due to other solid tumors or lytic lesions due to
multiple myeloma, denosumab was noninferior to zoledronic acid in delaying the
time to first SRE following randomization.
Overall survival and progression-free survival were
similar between arms in all three trials.
Table 2: Efficacy Results for Denosumab Compared to
Zoledronic Acid
| |
Study 20050136 Metastatic Breast Cancer |
Study 20050244 Metastatic Solid Tumors or Multiple Myeloma |
Study 20050103 Metastatic CRPCa |
Denosumab
N = 1026 |
Zoledronic Acid
N = 1020 |
Denosumab
N = 886 |
Zoledronic Acid
N = 890 |
Denosumab
N = 950 |
Zoledronic Acid
N = 951 |
| First On-study SRE |
| Number of Patients who had SREs (%) |
315 (30.7) |
372 (36.5) |
278 (31.4) |
323 (36.3) |
341 (35.9) |
386 (40.6) |
| Components of First SRE |
| Radiation to Bone |
82 (8.0) |
119 (11.7) |
119 (13.4) |
144 (16.2) |
177 (18.6) |
203 (21.3) |
| Pathological Fracture |
212 (20.7) |
238 (23.3) |
122 (13.8) |
139 (15.6) |
137 (14.4) |
143 (15.0) |
| Surgery to Bone |
12 (1.2) |
8 (0.8) |
13 (1.5) |
19 (2.1) |
1 (0.1) |
4 (0.4) |
| Spinal Cord Compression |
9 (0.9) |
7 (0.7) |
24 (2.7) |
21 (2.4) |
26 (2.7) |
36 (3.8) |
| Median Time to SRE (months) |
NRb |
26.4 |
20.5 |
16.3 |
20.7 |
17.1 |
| Hazard Ratio (95% CI) |
0.82 (0.71, 0.95) |
0.84 (0.71, 0.98) |
0.82 (0.71, 0.95) |
| Noninferiority p-value |
< 0.001 |
< 0.001 |
< 0.001 |
| Superiority p-valuec |
0.010 |
0.060 |
0.008 |
| First and Subsequent SREd |
| Mean Number/Patient |
0.46 |
0.60 |
0.44 |
0.49 |
0.52 |
0.61 |
| Rate Ratio (95% CI) |
0.77 (0.66, 0.89) |
0.90 (0.77, 1.04) |
0.82 (0.71, 0.94) |
| Superiority p-valuee |
0.001 |
0.145 |
0.009 |
a CRPC = castrate-resistant prostate cancer.
b NR = not reached.
c Superiority testing performed only after denosumab demonstrated to
be noninferior to zoledronic acid within trial.
d All skeletal events postrandomization; new events defined by
occurrence ≥ 21 days after preceding event.
e Adjusted p-values are presented. |
Multiple Myeloma
The efficacy of denosumab for the prevention of
skeletal-related events in newly diagnosed multiple myeloma patients with
treatment through disease progression, was evaluated in Study 20090482
(NCT01345019), an international, randomized (1:1), double-blind,
active-controlled, noninferiority trial comparing denosumab with zoledronic
acid. In this trial, patients were randomized to receive 120 mg denosumab
subcutaneously every 4 weeks or 4 mg zoledronic acid intravenously (IV) every 4
weeks (dose adjusted for reduced renal function). Patients with creatinine
clearance less than 30 mL/min were excluded. In this trial, the main efficacy
outcome measure was noninferiority of time to first skeletal-related event
(SRE). Additional efficacy outcome measures were superiority of time to first
SRE, time to first and subsequent SRE, and overall survival. An SRE was defined
as any of the following: pathologic fracture, radiation therapy to bone,
surgery to bone, or spinal cord compression.
Study 20090482 enrolled 1718 newly diagnosed multiple
myeloma patients with bone lesions. Randomization was stratified by a history
of prior SRE (yes or no), the anti-myeloma agent being utilized/planned to be
utilized in first-line therapy (novel therapy-based or non-novel therapy-based
[novel therapies include bortezomib, lenalidomide, or thalidomide]), intent to
undergo autologous PBSC transplantation (yes or no), stage at diagnosis
(International Staging System I or II or III) and region Japan (yes or no). At
study enrollment, 96% of the patients were receiving or planning to receive
novel therapy-based first-line anti-myeloma therapy, 55% of the patients
intended to undergo autologous PBSC transplantation, 61% of patients had a previous
SRE, 32% were at ISS stage I, 38% were at ISS stage II and 29% were at ISS
Stage III, and 2% were enrolled from Japan. Median age was 63 years, 82% of
patients were White, and 46% of patients were women. The median number of doses
administered was 16 for denosumab and 15 for zoledronic acid.
Denosumab was noninferior to zoledronic acid in delaying
the time to first SRE following randomization (HR = 0.98, 95% CI, 0.85-1.14).
The results for overall survival (OS) were comparable between denosumab and
zoledronic acid treatment groups with a hazard ratio of 0.90 (95% CI: 0.70,
1.16).
Table 3: Efficacy Results for Denosumab Compared to
Zoledronic Acid
| |
Study 20090482 Multiple Myeloma |
Denosumab
N = 859 |
Zoledronic Acid
N = 859 |
| First On-study SRE |
| Number of Patients who had SREs (%) |
376 (43.8) |
383 (44.6) |
| Components of First SRE |
| Radiation to Bone |
47 (5.5) |
62 (7.2) |
| Pathological Fracture |
342 (39.8) |
338 (39.3) |
| Surgery to Bone |
37 (4.3) |
48 (5.6) |
| Spinal Cord Compression |
6 (0.7) |
4 (0.5) |
| Median Time to SRE (months) (95% CI) |
22.8 (14.7, NEa) |
24 (16.6, 33.3) |
| Hazard Ratio (95% CI) |
0.98 (0.85, 1.14) |
| a NE = not estimable |
Giant Cell Tumor Of Bone
The safety and efficacy of denosumab for the treatment of
giant cell tumor of bone in adults or skeletally mature adolescents were
demonstrated in two open-label trials [Study 20040215 (NCT00396279) and Study
20062004 (NCT00680992)] that enrolled patients with histologically confirmed
measurable giant cell tumor of bone that was either recurrent, unresectable, or
for which planned surgery was likely to result in severe morbidity. Patients
received 120 mg denosumab subcutaneously every 4 weeks with a loading dose on
Days 8 and 15 of the first cycle of therapy. Patients who discontinued
denosumab then entered the safety follow-up phase for a minimum of 60 months.
Retreatment with denosumab while in safety follow-up was allowed for patients
who initially demonstrated a response to denosumab (e.g., in the case of
recurrent disease).
Study 20040215 was a single-arm, pharmacodynamic, and
proof of concept trial conducted in 37 adult patients with unresectable or
recurrent giant cell tumor of bone. Patients were required to have histologically
confirmed giant cell tumor of bone and radiologic evidence of measurable
disease from a computed tomography (CT) or magnetic resonance imaging (MRI)
obtained within 28 days prior to study enrollment. Patients enrolled in Study
20040215 underwent CT or MRI assessment of giant cell tumor of bone at baseline
and quarterly during denosumab treatment.
Study 20062004 was a parallel-cohort, proof of concept,
and safety trial conducted in 535 adult or skeletally mature adolescent
patients with histologically confirmed giant cell tumor of bone and evidence of
measurable active disease. Study 20062004 enrolled 19 patients who were 12-16
years of age [see Use In Specific Populations]. Patients enrolled into
one of three cohorts: Cohort 1 enrolled 268 patients with surgically
unsalvageable disease (e.g., sacral or spinal sites of disease, or pulmonary
metastases); Cohort 2 enrolled 252 patients with surgically salvageable disease
where the investigator determined that the planned surgery was likely to result
in severe morbidity (e.g., joint resection, limb amputation, or
hemipelvectomy); Cohort 3 enrolled 15 patients who previously participated in
Study 20040215. Patients underwent imaging assessment of disease status at
intervals determined by their treating physician.
A retrospective interim analysis concluded by an
independent review committee evaluated objective response in 187 patients
enrolled and treated in Study 20040215 and Study 20062004 for whom baseline and
at least one post-baseline radiographic assessment were available (27 of 37
patients enrolled in Study 20040215 and 160 of 270 patients enrolled in Cohorts
1 and 2 of Study 20062004). The primary efficacy outcome measure was objective
response rate using Response Evaluation Criteria in Solid Tumors (RECIST) v
1.1.
The overall objective response rate (RECIST 1.1) was 25%
(95% CI: 19, 32). All responses were partial responses. The estimated median
time to response was 3 months. In the 47 patients with an objective response,
the median duration of follow-up was 20 months (range: 2-44 months), and 51%
(24/47) had a duration of response lasting at least 8 months. Three patients
experienced disease progression following an objective response.
Hypercalcemia Of Malignancy
The safety and efficacy of denosumab was demonstrated in
an open-label, single-arm trial [Study 20070315 (NCT00896454)] that enrolled 33
patients with hypercalcemia of malignancy (with or without bone metastases)
refractory to treatment with intravenous bisphosphonate therapy. Patients
received denosumab subcutaneously every 4 weeks with additional 120 mg doses on
Days 8 and 15 of the first month of therapy.
In this trial, refractory hypercalcemia of malignancy was
defined as an albumin-corrected calcium of > 12.5 mg/dL (3.1 mmol/L) despite
treatment with intravenous bisphosphonate therapy in 7-30 days prior to
initiation of denosumab therapy. The primary outcome measure was the proportion
of patients achieving a response, defined as corrected serum calcium (CSC)
≤ 11.5 mg/dL (2.9 mmol/L), within 10 days after denosumab administration.
Efficacy data are summarized in Figure 1 and Table 4. Concurrent chemotherapy
did not appear to affect response to denosumab.
Figure 1: Corrected Serum Calcium by Visit in
Responders (Median and Interquartile Range)
N = Number of responders who received ≥ 1 dose of
investigational product n = Number of responders who had no missing data at
baseline and the time point of interest
Table 4: Efficacy in Patients with Hypercalcemia of
Malignancy Refractory to Bisphosphonate Therapy
| |
N = 33 |
Proportion (%) (95% CI) |
| All Responders (CSC ≤ 11.5 mg/dL) by Day 10 |
21 |
63.6
(45.1, 79.6) |
| All Responders by Day 57 |
23 |
69.7
(51.3, 84.4) |
| Complete Responders (CSC ≤ 10.8 mg/dL) by Day 10 |
12 |
36.4
(20.4, 54.9) |
| All Complete Responders by Day 57 |
21 |
63.6
(45.1, 79.6) |
Median time to response (CSC ≤ 11.5 mg/dL) was 9
days (95% CI: 8, 19), and the median duration of response was 104 days (95% CI:
7, not estimable). Median time to complete response (CSC ≤ 10.8 mg/dL)
was 23 days (95% CI: 9, 36), and the median duration of complete response was
34 days (95% CI: 1, 134).