DEPARTMENT OF HEALTH AND
HUMAN SERVICES
PUBLIC HEALTH SERVICE
FOOD AND DRUG ADMINISTRATION
CENTER FOR DRUG EVALUATION AND RESEARCH
Medical Division: Oncology Drug Products (HFD-150)
Biometrics
Division: Division of Biometrics I (HFD-710)
NDA NUMBER: 21-386
DRUG
NAME: ZometaÒ (zoledronic
acid for injections)
INDICATION: Treatment of Bone Metastases
SPONSOR: Novartis
DOCUMENTS
REVIEWED: 1, 67, 68, 92, 94,
97, 98, 100, 106, 107, 109, 112, 114, 115
STATISTICAL REVIEWERS: Rajeshwari
Sridhara, Ph.D. (HFD‑710)
Ning
Li, Ph.D. (HFD-710)
STATISTICAL TEAM LEADER: Gang
Chen, Ph.D. (HFD‑710)
BIOMETRICS DIVISION
DIRECTOR: George Chi, Ph.D. (HFD‑710)
CLINICAL REVIEWERS: Amna Ibrahim, M.D. (HFD‑150)
Nancy
Scher, M.D. (HFD-150)
Grant
Williams, M.D. (HFD-150)
PROJECT MANAGER: Debra Vause (HFD‑150)
Distribution: NDA 21-386
HFD‑150/Vause
HFD‑150/Ibrahim
HFD-150/Scher
HFD-150/Williams
HFD‑150/Pazdur
HFD‑710/Sridhara
HFD-710/Li
HFD‑710/Chen
HFD‑710/Mahjoob
HFD-710/Chi
HFD‑710/Anello
File Directory:
C:/nda/novartis/zometa_stat_odac_review.doc
Table of Contents
1 Executive Summary and Statistical
Findings....................................................................................... 1
1.1 Overview of the Studies Reviewed.............................................................................................. 1
1.2 Some Statistical and Technical Issues........................................................................................ 2
1.3 Principal Findings........................................................................................................................... 3
2 Statistical Review and Evaluation of
Evidence................................................................................... 9
2.1 Introduction..................................................................................................................................... 9
2.2 Some Statistical Issues:............................................................................................................... 10
2.3 Study 010 (Breast cancer or multiple
myeloma patients with bone metastasis).................. 11
2.3.1 Background.......................................................................................................................... 11
2.3.2 Data Analyzed and Sources............................................................................................... 11
2.3.3 Study Objectives................................................................................................................. 11
2.3.4 Efficacy Endpoints.............................................................................................................. 12
2.3.5 Sample Size Considerations............................................................................................... 12
2.3.6 Stratification......................................................................................................................... 12
2.3.7 Interim Analysis................................................................................................................... 12
2.3.8 Efficacy Analysis Methods............................................................................................... 12
2.3.9 Sponsor’s Results and Statistical
Reviewer’s Findings/Comments............................ 13
2.3.10 Sponsor’s Conclusion and Reviewer’s
Conclusion/Comments................................... 23
2.4 Study 011 (Cancer patients with bone
metastasis, other than breast cancer, multiple myeloma or prostate cancer) 24
2.4.1 Background.......................................................................................................................... 24
2.4.2 Data Analyzed and Sources............................................................................................... 24
2.4.3 Study Objectives................................................................................................................. 24
2.4.4 Efficacy Endpoints.............................................................................................................. 25
2.4.5 Sample Size Considerations............................................................................................... 25
2.4.6 Stratification......................................................................................................................... 26
2.4.7 Interim Analysis................................................................................................................... 26
2.4.8 Efficacy Analyses Methods.............................................................................................. 26
2.4.9 Sponsor's Results and Reviewer's
Findings/Comments................................................ 28
2.4.10 Sponsor's Conclusions and Reviewer's
Conclusions/Comments................................ 42
2.5 Study 039 (Prostate cancer patients with
metastatic bone lesions)...................................... 44
2.5.1 Background.......................................................................................................................... 44
2.5.2 Data Analyzed and Sources............................................................................................... 44
2.5.3 Study Objectives................................................................................................................. 44
2.5.4 Efficacy Endpoints.............................................................................................................. 45
2.5.5 Sample Size Considerations............................................................................................... 45
2.5.6 Stratification......................................................................................................................... 46
2.5.7 Interim Analysis................................................................................................................... 46
2.5.8 Efficacy Analysis Methods............................................................................................... 46
2.5.9 Sponsor's Results and Reviewer's
Findings/Comments................................................ 48
2.5.10 Sponsor’s Conclusions and Reviewer’s Conclusions/Comments............................... 61
3 Statistical Evaluation of Collective
Evidence.................................................................................... 64
4 APPENDICES......................................................................................................................................... 68
4.1 APPENDIX 1 - STUDY 010 - Zol. 8/4 mg
versus Aredia........................................................ 68
4.2 APPENDIX 2 - STUDY 011 - Zol. 8/4 mg
versus Placebo...................................................... 71
4.3 APPENDIX 3 - STUDY 039 - Zol. 8/4 mg
versus Placebo...................................................... 72
ZometaÒ or zoledronate (zoledronic acid for
injection) is proposed to be used for the treatment of osteolytic,
osteoblastic, and mixed bone metastases of solid tumors and osteolytic lesions
of multiple myeloma, in conjunction with standard antineoplastic therapy in
cancer patients. ZometaÒ is a member of a class of compounds known as
bisphosphonates and it is a third generation bisphosphonate. Bisphosphonates are effective inhibitors of
osteoclastic bone resorption. ZometaÒ has been approved for the
treatment of hypercalcemia of malignancy.
The current NDA application describes three ranomized clinical trials
with ZometaÒ in the treatment of cancer
patients with bone metastases.
Study
010 was a multicenter, double-blind, randomized, controlled, Phase III parallel
comparative trial of i.v. zoledronic acid
(Zometa, 4 mg or 8 mg) versus iv. Aredia (90 mg) (pamidronate) as an
adjunct to standard therapies in patients with multiple myeloma and breast cancer
with cancer related bone lesions. The active control agent, intravenous pamidronate
(90 mg) is the current standard of care for the treatment of patients with
predominantly osteolytic bone metastases from breast cancer and osteolytic
lesions associated with multiple myeloma. Pamidronate (90 mg via 2- to 4-hour
infusion every 3 to 4 weeks) has been shown to significantly prolong the time
to first skeletal-related event (SRE) and to significantly reduce the incidence
of SREs for up to 21 months in patients with multiple myeloma and up to 2 years
in patients with breast cancer and osteolytic lesions compared with placebo. A
total of one-thousand-six-hundred-and-forty-eight (1648) patients were
randomized in this trial: 564 patients in the zoledronic acid 4 mg treatment
group, 526 patients in the zoledronic acid 8/4 mg treatment group and 558
patients in the Aredia 90 mg treatment group. The study was stratified
by three cancer patient groups: Myeloma, Breast cancer with chemotherapy and
breast cancer with hormonal therapy. The primary objective of study 010 was to
show “non-inferiority” of i.v. Zometa to Aredia in preventing skeletal-related
events (SRE) in Stage III myeloma or Stage IV breast cancer patients with
cancer related bone lesions. The primary
efficacy endpoint was the proportion of patients experiencing at least one SRE
up to 13 months, defined as, radiation therapy to bone, surgery to bone,
pathologic bone fracture or spinal cord compression.
Study
011 was a randomized, double-blind, multicenter, parallel-group, placebo
controlled Phase III study conducted in a total of 773 patients aged 18 years
or over with ECOG performance status # 2 and bone metastases from
solid tumors other than breast or prostate cancer. Patients were randomized in a double-blind fashion to receive
either zoledronate 4 mg intravenously, or zoledronate 8 mg intravenously, or a
placebo intravenous infusion every three weeks for 12 doses in addition to
their antineoplastic therapy. The
randomized treatment assignment ratio was to be 1:1:1 (257 patients were randomized
to the 4 mg zoledronic acid group, 266 patients to the 8 mg zoledronic acid
group, and 250 patients to the placebo group). The randomization was stratified
by site of cancer 'lung cancer' versus 'other solid tumor'. Patients were to be treated for 36 weeks (9
months). In addition, all patients were
to receive 500 mg of calcium orally and a multivitamin tablet (containing 500
I.U. of vitamin D) daily throughout the study. The primary study objective of
this study was to assess the efficacy of zoledronate therapy (4 or 8 mg) in
addition to antineoplastic therapy, compared to antineoplastic therapy alone,
in preventing skeletal-related events in patients with any cancer with bone
metastases other than breast cancer, multiple meyeloma or prostate cancer. The
primary efficacy variable was the proportion of patients with any SRE exclusive
of tumor induced hypercalcemia (TIH or -HCM)) at 9 months.
Study 039 was an international, multicenter,
randomized, double-blind, placebo-controlled, parallel study conducted in
prostate cancer patients with a history of metastatic bone disease who have a
rising serum PSA concentration despite treatment with first-line hormonal
therapy for meatastatic disease.
Patients were randomized in a double-blind fashion to receive either
zoledronate 4 mg intravenously, or zoledronate 8 mg intravenously, or a placebo
intravenous infusion every three weeks in addition to their antineoplastic
therapy. The randomized treatment
assignment ratio was to be 1:1:1 (214 patients were randomized to zoledronate 4
mg, 221 patients to the zoledronate 8 mg group, and 208 patients to the placebo
group). The randomization was stratified by prostate cancer history (no
metastatic disease present at the time of the initial diagnosis of prostate
cancer versus metastatic disease present at the time of the initial
diagnosis). In addition all patients
were to receive 500 mg of calcium orally and multivitamin tablet (containing
400-500 I.U. of vitamin D) daily throughout the study. The primary objective of
this study was to assess the efficacy of zoledronate treatments (4 or 8 mg) in
addition to antineoplastic therapy, compared to antineoplastic therapy alone to
prevent skeletal-related events (SREs) in prostate cancer patients with a
history of metastatic bone disease who have developed biochemical progression
of disease. SREs were defined as
pathologic bone fracture events, spinal cord compression events, surgery to
bone, and radiation therapy to bone (including the use of radioisotopes). The
primary efficacy variable in this study was the proportion of patients having
at least one skeletal-related event at 15 months.
·
The
protocol stated objective of showing “non-inferiority” of i.v. Zometa to Aredia
in study 10 is not appropriate according to the current understanding of
non-inferiority trials. The objective should have been stated as demonstrating
the effectiveness
of i.v. Zometa through a non-inferiority trial with Aredia as the active
comparator.
·
The
protocol defined primary efficacy parameter in all the three studies is
proportion of skeletal related events.
This proportion was computed in each treatment arm as the ratio of the
number of first skeletal related events at 12, 9 and 15 months in studies 010,
011 and 039, respectively, to the number of patients randomized to the
treatment arm. These estimates of the
skeletal event rates may be biased as there is high dropout rate: ³ 27% in study 010 (at 12 months), ³ 56% in study 011 (at 9 months), and ³ 46% in study 039 (at 15 months).
·
Time
to first occurrence of skeletal-related event is preferred to the protocol
specified analysis of proportion of skeletal-related events and it was
recommended by the agency (statistical reviews dated 6/18/98 and 8/20/98). Due to high dropout rate in all three
studies, the analysis of proportion at a
fixed time point is questionable.
The time to skeletal-related event analysis should be considered as the
primary analysis, which can take into account censoring of observations during
the course of the study.
·
In
all the three studies, the 8 mg ZometaÒ treated arm was not
included in the efficacy evaluation because of the Amendment 4 of the protocols
to decrease the dose to 4 mg of every patient in the 8 mg due to observed renal
toxicity. This change occurred after
all the patients were enrolled in each of the studies and the patients in the 8
mg arm had received substantial treatment.
However, if the efficacy
analysis for the 8 mg arm was also performed then type I error rate should be
adjusted in the comparisons of 4 mg versus placebo treated arms.
Study 010:
The primary efficacy endpoint was the proportion of
patients experiencing at least one SRE, defined as radiation therapy to bone,
surgery to bone, pathologic bone fracture or spinal cord compression. The
sponsor’s analysis result is summarized in Table 1.3.1.
Table 1.3.1:
Proportion of SRE to Month 13 by Stratum (Sponsor’s Analyses)
|
|
Zometa (4mg) |
Aredia |
Difference D (95% CI)* |
Log-rank p-value |
|
Myeloma |
47% (86/183) |
49% (82/167) |
-2% (-12.6%, 8.4%) |
0.694 |
|
Breast (Chemo) |
44% (79/178) |
43% (78/181) |
1% (-9%, 11.6%) |
0.806 |
|
Breast (Hormonal) |
42% (83/200) |
47% (97/207) |
-5% (-15%, 4.3%) |
0.277 |
|
Total |
44% (248/561) |
46% (257/555) |
-2% (-7.9%, 3.7%) |
0.461 OR=0.919 |
*D=Zometa-Aredia
During
design of the non-inferiority study, the sponsor defined a “non-inferiority”
margin of 8% which is based on preserving 60% of the point estimate of the
active control effect (Aredia vs. placebo). By reviewing the original protocol
and the original studies comparing Aredia with placebo, the active control
effect was determined based upon the following data (Table 1.3.2):
Table 1.3.2:
Active Control (Aredia vs. Placebo) Effect by Studies (012, 018, 019)
|
|
Placebo |
Aredia |
Difference
D (95%
CI)* |
Log-rank p-value |
|
Myeloma |
44% (79/179) |
28% (56/198) |
16% (6.2%, 25.5%) |
0.001 |
|
Breast (Chemo) |
56% (110/195) |
43% (79/185) |
13.7% (3.8%, 23.7%) |
0.007 |
|
Breast (Hormonal) |
55% (104/189) |
47% (85/182) |
8% (-1.8%, 18.5 %) |
0.108 |
|
Total |
52.0% (293/563) |
38.9% (220/565) |
13.1% (7.3%, 18.9%) |
<0.0001 OR**=1.702 |
From current understanding of active control non-inferiority trial, margins defined in terms of point estimate of the control effect tends to be liberal [1, 2, 3]. Since there is only one active control non-inferiority trial and there are only a few historical randomized studies for the assessment of the control effect, the margin of the non-inferiority test should be defined based on an Aredia effect estimated by the lower limit of the 95% CI.
Table 1.3.3 summarizes the results of “Non-inferiority” analysis for study 010.
Table 1.3.3: Results of “Non-inferiority” Analysis
|
Method |
Zole
4mg-Aredia D (95% CI) |
Placebo- Aredia D (95% CI) |
“Non-inferiority” Test** |
|
8% Margin |
-2% (-7.9%,3.7%) |
|
Yes (Upper limit 3.7% <8%) |
|
3.65%* Margin |
-2% (-7.9%,3.7%) |
13.1% (7.3%,18.9%) |
No (Upper limit
3.7%>3.65%) |
*
3.65% margin is calculated based on 50% of the lower limit of 95% CI of the
estimator of the Aredia effect.
**
Test result is significant at 0.05 level if the upper limit of 95% CI of Zometa
effect (3.7%) is less than the given margin.
Table 1.3.4 summarizes the results of time to first SRE analysis for study 010.
Table 1.3.4: Time to
First SRE by Stratum and Treatment Arm
|
|
N |
Median (95%CI) |
Hazard
Ratio (95% CI) |
Log-rank
p-value |
|
Myeloma Aredia Zol 4 mg |
167 183 |
301(191,
---) 372(225,
504) |
.97(.71,
1.31) |
0.82 |
|
Breast(CT) Aredia Zol 4 mg |
181 178 |
366(259,
---) 364(249,
---) |
.96(.70,
1.32) |
0.81 |
|
Breast(HT) Aredia Zol 4 mg |
207 200 |
370(258,
---) >380
(---, --) |
.83(.62,
1.12) |
0.22 |
|
Total Aredia Zol 4 mg |
555 561 |
363(273, 399) 373(350, 504) |
.92(.77, 1.09) |
0.31 |
Study 011:
The
primary efficacy variable was the proportion of patients experiencing at least
one SRE (-HCM). Per sponsor analysis by
month 9 both the zoledronic acid 4 mg and 8/4 mg groups had a lower proportion
than the placebo group (Table 1.3.5).
Table 1.3.5: Proportion of Patients Having SRE (-HCM) up to Month 9 by Stratum and Treatment Group (ITT Patients) – Sponsor’s Analysis
|
|
|
95% C.I. and P-value for the difference |
|
|
|
Proportion |
Zol 4 mg |
Zol 8/4 mg |
|
Lung Cancer |
|
|
|
|
Placebo |
59/130 (45%) |
(-15.6%,8.4%), p=0.557 |
(-23.3%,0.1%), p=0.053 |
|
Zol 4 mg |
56/134 (42%) |
- |
(-19.5%,3.5%), p=0.175 |
|
Zol 8/4 mg |
47/139(34%) |
- |
- |
|
Other Solid Tumors |
|
|
|
|
Placebo |
52/120 (43%) |
(22.2%,2.2%), p=0.110 |
(-20.1%,4.3%), p=0.205 |
|
Zol 4 mg |
41/123 (33%) |
- |
(-9.7%,13.9%), p=0.727 |
|
Zol 8/4 mg |
45/127 (35%) |
- |
- |
|
Total |
|
|
|
|
Placebo |
111/250 (44%) |
(-15.2%,1.9%), p=0.127 |
(-18.2%,-1.4%), p=0.023 |
|
Zol 4 mg |
97/257 (38%) |
- |
(-11.4%,5.1%), p=0.452 |
|
Zol 8/4 mg |
92/266 (35%) |
- |
- |
Table 1.3.6 summarizes the results of time to first
SRE analysis for study 011.
Table 1.3.6:
Analysis of Time to First Skeletal Related Event Truncated at 9 Months Using
Kaplan-Meier Estimation Procedure (ITT Population FDA Analysis)
|
|
Event Rate at 9 Months |
N |
Median Time to Event in days (95% C.I.) |
Hazard Ratio (95% C.I.) |
P-value (Comparison to Placebo using Log-rank
test) |
|
Lung Cancer |
|
|
|
|
|
|
Placebo |
67.9% |
130 |
151 (90, 202) |
|
|
|
Zol 4 mg |
60.7% |
133 |
168 (154, *) |
0.785 (0.544, 1.132) |
0.19 |
|
Zol 8/4 mg |
53.6% |
139 |
249 (175, *) |
0.673 (0.459, 0.987) |
0.04 |
|
Other Solid Tumors |
|
|
|
|
|
|
Placebo |
58.2% |
120 |
168 (106, *) |
|
|
|
Zol
4 mg |
43.9% |
123 |
* (174, *) |
0.664 ( 0.438, 1.009) |
0.05 |
|
Zol 8/4 mg |
52.4% |
127 |
198 (156, *) |
0.826 (0.553, 1.234) |
0.35 |
|
Total |
|
|
|
|
|
|
Placebo |
63.2% |
250 |
163 (106, 188) |
|
|
|
Zol 4 mg |
52.8% |
256 |
230 (168, *) |
0.733 (0.557, 0.965) |
0.026 |
|
Zol 8/4 mg |
53.0% |
266 |
219 (172, *) |
0.743 (0.563, 0.980) |
0.035 |
* = Not Reached
Study 039:
The primary efficacy variable was the proportion of
patients experiencing at least one SRE (-HCM).
Per sponsor analysis by month 15 both the zoledronic acid 4 mg and 8/4
mg groups had a lower proportion than the placebo group (Table 1.3.7).
Table 1.3.7: Proportion of Patients Having SRE (-HCM) up to Month 15 by Stratum and Treatment Group (ITT Patients) – Sponsor’s Analysis
|
|
|
95% C.I. and P-value for the difference |
|
|
|
Proportion |
Zol 4 mg |
Zol 8/4 mg |
|
No Initial Metastases |
|
|
|
|
Placebo |
54/116 (47%) |
(-24.4%,0.9%), p=0.069 |
(-21.5%,3.0%), p=0.140 |
|
Zol 4 mg |
40/115 (35%) |
- |
(-9.4%,14.5%), p=0.679 |
|
Zol 8/4 mg |
50/134 (37%) |
- |
- |
|
With Initial Metastases |
|
|
|
|
Placebo |
38/92 (41%) |
(-23.6%,3.6%), p=0.152 |
(-15.5%,13.3%), p=0.884 |
|
Zol 4 mg |
31/99 (31%) |
- |
(-4.9%,22.7%), p=0.206 |
|
Zol 8/4 mg |
35/87 (40%) |
- |
- |
|
Total |
|
|
|
|
Placebo |
92/208 (44%) |
(-20.3%,-1.8%), p=0.021 |
(-15.1%,3.6%), p=0.222 |
|
Zol 4 mg |
71/214 (33%) |
- |
(-3.7%, 14.3%), p=0.255 |
|
Zol 8/4 mg |
85/221 (38%) |
- |
- |
Table 1.3.8 summarizes the
results of time to first SRE analysis for study 039.
Table 1.3.8:
Analysis of Time to First Skeletal Related Event Truncated at 15 Months Using
Kaplan-Meier Estimation Procedure (ITT Population FDA Analysis)
|
|
Event Rate at 9 Months |
N |
Median Time to Event in days (95% C.I.) |
Hazard Ratio (95% C.I.) |
P-value (Comparison to Placebo using
Log-rank test) |
|
No Initial
Metastases |
|
|
|
|
|
|
Placebo |
59.6% |
116 |
304 (198, *) |
|
|
|
Zol 4 mg |
45.6% |
115 |
* (291, *) |
0.673 (0.446, 1.016) |
0.058 |
|
Zol 8/4 mg |
50.7% |
134 |
419 (251, *) |
0.805 (0.547, 1.185) |
0.270 |
|
With Initial
Metastases |
|
|
|
|
|
|
Placebo |
54.0% |
92 |
335 (244, *) |
|
|
|
Zol 4 mg |
44.4% |
99 |
* (364, *) |
0.673 (0.446, 1.016) |
0.085 |
|
Zol 8/4 mg |
57.0% |
87 |
346 (209, *) |
1.091 (0.689, 1.728) |
0.709 |
|
Total |
|
|
|
|
|
|
Placebo |
57.2% |
208 |
321 (252, *) |
|
|
|
Zol 4 mg |
44.9% |
214 |
* (383, *) |
0.661 (0.484, 0.903) |
0.009 |
|
Zol 8/4 mg |
53.2% |
221 |
363 (255, *) |
0.912 (0.679, 1.226) |
0.541 |
* =
Not Reached
3.1 Conclusions
The “non-inferiority” test in Study 010 demonstrates
marginal effectiveness (p=0.052) with respect to proportion of SREs at 12
months of zoledronate 4mg arm, using a margin of 3.65% which is defined as
preserving 50% of the lower limit of the 95% CI of the point estimate of the
Aredia effect. The original selection of 8% margin is not acceptable based on
the current understanding because it tends to be liberal.
Study 011 has failed to demonstrate efficacy of 4 mg
zoledronate over placebo treated group in reducing the proportion of SREs at 9
months per protocol specified analysis (P-value=0.127). The protocol specified estimates of the
proportion of SREs may be biased estimates because of high dropout rate. The
sponsor was advised by the agency during the protocol development stage to
consider time to first SRE as the primary efficacy parameter, which can take
into account censoring of observations during the course of the study. Therefore, in order to account for the early
censoring of the observations, this reviewer conducted time to first SRE
analysis using Kaplan-Meier estimation procedure, which was recommended by the agency as the primary analysis,
truncating the maximum follow up time at 9 months. There appears to be a statistically
significant difference between the Zoledronate 4 mg group and placebo group
(p=0.026, 2-sided log-rank test) by this analysis.
In study 039, there is a statistically significant difference between zoledronate 4 mg
and placebo groups (p=0.021) with respect to the proportion of SREs at 15
months as defined in the protocol. However, the per protocol estimates of the
proportion of SREs may be biased estimates because of high dropout rate. The
sponsor was advised by the agency during the protocol development stage to
consider time to first SRE as the primary efficacy parameter, which can take
into account censoring of observations during the course of the study. Therefore, in order to account for the early
censoring of the observations, this reviewer conducted time to first SRE
analysis using Kaplan-Meier estimation procedure, truncating the maximum follow
up time at 15 months. There is a
statistically significant difference between the zoledronate 4 mg group and
placebo group (p=0.009, 2-sidered log-rank test).
In
these reviewers' opinion the results of Studies 11 and 39 support efficacy of
zoledronate 4 mg given intravenously versus placebo given intravenously in
patients with bone metastases from solid tumors other than breast cancer, and
the results of Study 10 suggest
marginal effectiveness of zoledronate 4 mg given intravenously in patients with
bone metastases from breast cancer and multiple myeloma based on a
“non-inferiority” test using Aredia as the active control .
ZometaÒ or zoledronate (zoledronic acid for
injection) is proposed to be used for the treatment of osteolytic,
osteoblastic, and mixed bone metastases of solid tumors and osteolytic lesions
of multiple myeloma, in conjunction with standard antineoplastic therapy in
cancer patients. ZometaÒ is a member of a class of compounds known as
bisphosphonates and it is a third generation bisphosphonate. Bisphosphonates are effective inhibitors of
osteoclastic bone resorption. ZometaÒ has been approved for the
treatment of hypercalcemia of malignancy.
The
current NDA application describes clinical trials with ZometaÒ in the treatment of cancer patients with
bone metastases. Pivotal efficacy data
in the treatment of bone metastases are provided by three double-blind studies
(010, 011 and 039), two of which (011, 039) were placebo-controlled, and the
other (010) active-controlled, the active control being pamidronate (ArediaÒ).
Study 010 was conducted in patients with bone metastases breast cancer
or multiple myeloma. Study 011 was
conducted in patients with any cancer with bone metastases other than breast
cancer, multiple myeloma or prostate cancer.
Study 039 was conducted in prostate cancer patients with bone lesions.
Statistical
review and evaluation of evidence of each of the studies 010, 011 and 039 are
presented, respectively, in sections 2.3, 2.4 and 2.5 of this review. An overall statistical evaluation of
collective evidence and conclusions are presented in section 3 of this review.
·
The
protocol stated objective of showing “non-inferiority” of i.v. Zometa to Aredia
in study 10 is not appropriate according to the current understanding of
non-inferiority trials. The objective should have been stated as demonstrating
the effectiveness
of i.v. Zometa through a
non-inferiority trial with Aredia as the active comparator.
·
The
protocol defined primary efficacy parameter in all the three studies is
proportion of skeletal related events.
This proportion was computed in each treatment arm as the ratio of the
number of first skeletal related events at 12, 9 and 15 months in studies 010,
011 and 039, respectively, to the number of patients randomized to the
treatment arm. These estimates of the
skeletal event rates may be biased as there is high dropout rate: ³ 27% in study 010 (at 12 months), ³ 56% in study 011 (at 9 months), and ³ 46% in study 039 (at 15 months).
·
Time
to first occurrence of skeletal-related event is preferred to the protocol
specified analysis of proportion of skeletal-related events and it was
recommended by the agency (statistical reviews dated 6/18/98 and 8/20/98). Due to high dropout rate in all three
studies, the analysis of proportion at a time point is questionable. The time to skeletal-related event analysis
should be considered as the primary analysis, which can take into account
censoring of observations during the course of the study.
·
In
all the three studies, the 8 mg ZometaÒ treated arm was not
included in the efficacy evaluation because of the Amendment 4 of the protocols
to decrease the dose to 4 mg of every patient in the 8 mg due to observed renal
toxicity. This change occurred after
all the patients were enrolled in each of the studies and the patients in the 8
mg arm had received substantial treatment.
However, if the efficacy
analysis for the 8 mg arm was also performed then type I error rate should be
adjusted in the comparisons of 4 mg versus placebo treated arms.
Study
010 was a multicenter, double-blind, randomized, controlled, phase III parallel
comparative trial of i.v. zoledronic acid
(Zometa, 4 mg or 8 mg) versus iv. Aredia (90 mg) (pamidronate) as an
adjunct to standard therapies in patients with multiple myeloma and breast
cancer with cancer related bone lesions.
The active control agent, intravenous pamidronate (90
mg), is the current standard of care for the treatment of patients with
predominantly osteolytic bone metastases from breast cancer and osteolytic
lesions associated with multiple myeloma. Pamidronate (90 mg via 2- to 4-hour
infusion every 3 to 4 weeks) has been shown to significantly prolong the time
to first skeletal-related event (SRE) and to significantly reduce the incidence
of SREs for up to 21 months in patients with multiple myeloma and up to 2 years
in patients with breast cancer and osteolytic lesions compared with placebo.
Study
010 was conducted in 21 countries including United States, Europe, Canada,
South Africa and Australia. A total of
one-thousand-six-hundred-and-forty-eight (1648) patients were randomized in
this trial: 564 patients in the zoledronic acid 4 mg treatment group, 526
patients in the zoledronic acid 8/4 mg treatment group and 558 patients in the
Aredia 90 mg treatment group. One site did not meet the GCP standards and 8
patients from this site were excluded from the efficacy analysis. The resulting
intention-to-treat population has 1640 patients.
Data used for review is from the electronic submission
received on 9/28/01. The network path is ”
cdsesub1\N21386\N_000\2001-10-02\\datasets\CRT\010 ” in the EDR. The following volumes were reviewed: 1, 67,
and 68.
The
primary objective of study 010 was to show non-inferiority of i.v. Zometa to
Aredia in preventing skeletal-related events (SRE) in Stage III myeloma or
Stage IV breast cancer patients with cancer related bone lesions. The study was
completed as planned in the protocol and its amendments. Due to reports of renal SAEs for zoledronic acid
8 mg, patients randomized to zoledronic acid 8 mg were later switched to
zoledronic acid 4 mg (Amendment 5; dated 07-Jun-2000); and their data would not
be used to support any efficacy claim.
The primary efficacy endpoint was the proportion of
patients experiencing at least one SRE, defined as radiation therapy to bone,
surgery to bone, pathologic bone fracture or spinal cord compression.
The secondary objectives were to compare the effects of
i.v. zoledronic acid 4 mg and/or 8 mg to i.v. Aredia 90 mg with respect to
safety and tolerability and the assessment of SRE with or without HCM; time to first SRE; time to
progression of bone metastases; time to overall progression of disease; quality
of life scores, and BMD.
For the purposes of sample size calculation, the
non-inferiority margin was set at 8%, which is approximately 60% of the
difference that was observed in the percentage of patients experiencing SREs
during the trials with Aredia and placebo (active vs. placebo).
To power for maximal variance, the percentage of
patients with SREs was assumed to be 50% for each treatment group. To test a
50% retention of Aredia effect with the type I error rate of 0.025 and 80% power
using a two-group large-sample normal approximation, the required number of
patients is 484 per arm. The actual
number of patients was sufficient enough for the assumed effect size.
The
study was stratified by three cancer patient groups: Myeloma, Breast cancer
with chemotherapy and breast cancer with hormonal therapy.
No
interim analysis for efficacy was planned for this study. However, at an
interim time point the 8 mg zoledronate arm was dropped due to renal toxicity
concerns. The sponsor claimed there was no efficacy interim look.
The analysis for the primary efficacy variable, the
proportion of patients who experience at least one SRE, exclusive of tumor
induced hypercalcemia (TIH), during the complete core phase participation up to
Month 13, is based upon the 95% CI of the rate difference. Either zoledronate
dose (4 or 8 mg) will be declared non-inferior to Aredia 90 mg if the upper
limit of the 95% confidence interval (2-sided) for the difference in the
percentage of patients having SREs after administration of zoledronate and
Aredia is below 8%. In terms of testing, this means that the statistical null
hypothesis to be tested is D ³ 8%
with the alternative hypothesis D < 8%, where D is
the above mentioned difference in percentages. The confidence interval will be
based on the large-sample normal approximation of the distribution of the
difference in the proportions.
Time to event
analysis was performed using log-rank test, Cox regression models and
Anderson-Gill approach for multiple events.
This
section will summarize the results of intention to treat analysis for study
010. The intention to treat patient population includes all patients as
randomized (but one site did not meet GCP and was excluded from the analysis).
All tests used in this review are two-sided unless otherwise stated.
The
baseline demographic characteristics including age, sex, races, weight, and
performance status were balanced between the two treatment groups (Zometa 4 mg
and Aredia 90 mg). The baseline disease
characteristics for both myeloma and breast cancer, including primary site of
mets, time to diagnoses, baseline serum creatinine, previous SRE, and baseline
quality of life scale scores were examined (Table 2.3.1). A slightly greater proportion of patients in the
Aredia 90 mg group had a performance status of ³ 2. Patients with multiple myeloma were slightly
older and a greater proportion were male than in the overall population. ECOG
status was also worse in this group compared with the overall population,
although time since initial diagnosis of cancer was much shorter.
Characteristics within this stratum were similar across treatment groups,
except that abnormal renal function was present in a lower proportion of
patients in the Aredia 90 mg group. Within each breast cancer stratum,
characteristics were generally similar across treatment groups, except that in
the stratum of patients with hormonal therapy, a lower proportion of patients
in the zoledronic acid 4 mg group than in the Aredia group were on first line
anti-neoplastic therapy or had brain metastases. (Table 2.3.1).

Table 2.3.1: Baseline Characteristics of Study 010 (Sponsor’s Analysis)
The primary efficacy endpoint was the proportion of
patients experiencing at least one SRE, defined as radiation therapy to bone,
surgery to bone, pathologic bone fracture or spinal cord compression. The
sponsor’s analysis result is summarized in Table 2.3.2.
Table 2.3.2: Proportion of SRE to Month 13 by Stratum (Sponsor’s Analyses)
|
|
Zometa (4mg) |
Aredia |
Difference D (95% CI)* |
p-value* |
|
Myeloma |
47% (86/183) |
49% (82/167) |
-2% (-12.6%, 8.4%) |
0.694 |
|
Breast (Chemo) |
44% (79/178) |
43% (78/181) |
1% (-9%, 11.6%) |
0.806 |
|
Breast (Hormonal) |
42% (83/200) |
47% (97/207) |
-5% (-15%, 4.3%) |
0.277 |
|
Total |
44% (248/561) |
46% (257/555) |
-2% (-7.9%, 3.7%) |
0.461 OR=0.919 |
*D=Zometa-Aredia
Reviewer’s
Comments:
1.
The
sponsor’s analysis shows that the
proportions were 44% and 46% for the zoledronic acid 4 mg group and the Aredia
90 mg group, respectively. The upper limit of the 95% confidence interval of
the difference was 3.7%, which was less than the non-inferiority margin of 8%
specified in the protocol. In the stratum of breast cancer patients receiving
hormonal therapy, the difference in the proportions between the zoledronic acid
4 mg group and the Aredia 90 mg group was –5%, which was the largest difference
of the three strata in this study. While In the stratum of breast cancer
patients receiving chemotherapy, the difference in the proportions between the
zoledronic acid 4 mg group and the Aredia 90 mg group was +1% with an upper
bound of 11.6%, implying 11.8% worse than Aredia.
2.
The
protocol stated objective of showing “non-inferiority” of i.v. Zometa to Aredia
in study 10 is not appropriate according to the current understanding of
non-inferiority trials. The objective should have been stated as demonstrating
the effectiveness of i.v. Zometa
through a non-inferiority trial with Aredia as the active comparetor.
During design of the non-inferiority study, the sponsor intended to preserve
60% of the point estimator of the active control effect (Aredia vs. placebo),
which resulted in an 8% non-inferiority margin. By reviewing the original
protocol and the original study comparing Aredia with placebo, the active
control effect was determined based upon the following data (Table 2.3.3):
Table 2.3.3: Active Control (Aredia vs. Placebo)
Effect by Stratum
|
|
Placebo |
Aredia |
Difference D (95% CI)* |
Log-rank p-value |
|
Myeloma |
44% (79/179) |
28% (56/198) |
16% (6.2%, 25.5%) |
0.001 |
|
Breast (Chemo) |
56% (110/195) |
43% (79/185) |
13.7% (3.8%, 23.7%) |
0.007 |
|
Breast (Hormonal) |
55% (104/189) |
47% (85/182) |
8% (-1.8%, 18.5 %) |
0.108 |
|
Total |
52.0% (293/563) |
38.9% (220/565) |
13.1% (7.3%, 18.9%) |
<0.0001 OR=1.702 |
*D=Placebo-Aredia
3.
The
overall SRE difference between placebo and Aredia was 13.1% with 95% CI lower
bound of 7.3%, which means that the Aredia was at least 7.3% better than a placebo in the Aredia trials for previous
approval. Thus, we may conclude that the active control effect using these
trials is 7.3% if we believe that the patient populations and other conditions
and parameters are similar in the historical trial and the current trial
(Constant Assumption).
4.
Concerns
about the constant assumption: To
design and analyze a non-inferiority study
such as Study 010, requires a
determination that the active control drug (Aredia) would have shown efficacy
in the new study or current setting, and it also requires an estimation of the
size of the effect that Aredia would have shown relative to a placebo in the
current setting. A comparison of the
previous Aredia/Placebo studies with the current Zometa/Aredia study has been
conducted. The comparison was performed as a comprehensive analysis on the issue
and consider such factors as the nature and stage of disease/previous
treatment; concomitant treatment; timing of events, duration of follow-up,
dropout rate, etc. According to the FDA reviewer’s request, the sponsor
provided a report regarding the comparability of the historical and current studies.
Detailed review of this issue can be found in Medical Officer’s NDA review. The
conclusion is summarized as follows.
The comparison was made using current study 010, historical trials 012,
018 and 019.
In the multiple myeloma population, the protocol 010 (current study) patients had a higher proportion of SREs at three months than did the protocol 012 (historical study) patients (25% compared to 10%), but the increase from 3 to 6 months in the proportion of patients with any SRE was similar (15% and 10%). The major differences between the study 010 and study 012 are that time since diagnosis was longer and previous history of an SRE was much less in the Aredia/placebo trial. Medical reviewer reviewed the data showed in tables below. These data demonstrated that the Aredia effect would be numerically larger in subgroup of patients with short time to diagnosis (<6 mo) as in the current trial (Table 2.3.4), and the Aredia treatment effect for patient with previous SRE is also larger than in patients had no SRE history (Table 2.3.5).
Table 2.3.4: Proportion of Myeloma Patients with SRE versus Time Since Diagnosis in
Study 012
|
|
Time since diagnosis |
|
|
> 6mo |
<6mo |
|
|
Aredia Proportion with SRE |
36/150 (24%) |
11/55 (20%) |
|
Placebo Proportion with SRE |
50/127 (39%) |
26/60 (43%) |
|
Placebo - Aredia |
15% |
23% |
Table
2.3.5: Proportion of Myeloma Patients
with SRE versus History of Previous SRE
|
|
History of SRE in previous 3 months |
|
|
|
Yes |
No |
|
Aredia Proportion with SRE |
35% (23/65) |
17% (24/240) |
|
Placebo Proportion with SRE |
58% (33/57) |
33% (43/130) |
|
Placebo - Aredia |
23% |
16% |
In conclusion, to use the effect of Aredia in study 012 in the testing of non-inferiority is a reasonable approach. In the population of breast cancer patients receiving hormonal treatment the proportions of patients with any SRE at 3 months were similar for the historical controls and the current population (32% and 28%). The increases in pathological fractures were identical, 6%, and were similar for radiation to bone, 5% and 8%. In the population of breast cancer patients receiving chemotherapy the proportion of patients with any SRE at 3 months was identical, and the increases in proportion of patients having any SRE, a pathological fracture or radiotherapy to bone were similar, indicating the consistent effect of Aredia inn the historical and current studies. In conclusion, when the known demographic and prognostic differences between the historical and current studies are taken into account the descriptive analyses reveal that Aredia had a similar effect in the previous and the current trials.
Preservation
of active control effect: The preservation of active treatment effect using the SRE rates can
be determined by (7.3%-3.7%)/7.3%=49.3%. Hence, the current trial demonstrated
an at least 49.3% retention of Aredia vs. a placebo effect if we believe that
the constant assumption holds. This
result demonstrates marginal effectiveness (p=0.052) with respect to proportion
of SREs at 12 months of zoledronate 4mg arm using a margin defined based on 50%
retention of the lower limit of 95% CI of the Aredia effect.
5.
The
SRE event rates over the study period (the longitudinal follow-up) are
presented in Tables 2.3.6 (the protocol defined event rate analysis) and 2.3.7.
(K-M estimated event rate). Numerically, the Zole 4mg arm shows similar effect
pattern to the Aredia arm.
Table 2.3.6: SRE Event Rate
(Intent-to-Treat Patients) over study period
|
Treatment |
N |
3 month |
6 month |
9 month |
12 month |
|
Myeoloma: Aredia 90 mg |
167 |
42
(25%) |
66
(40%) |
75
(45%) |
82
(49%) |
|
Zometa 4 mg |
183 |
56
(31%) |
70
(38%) |
74
(40%) |
86
(47%) |
|
Breast (Chemo): |
|
|
|
|
|
|
Aredia 90 mg |
181 |
49
(27%) |
64
(35%) |
72
(40%) |
78
(43%) |
|
Zometa 4 mg |
178 |
39
(22%) |
60
(34%) |
68
(38%) |
79
(44%) |
|
Breaset(Hormonal) |
|
|
|
|
|
|
Aredia 90 mg |
207 |
58
(28%) |
79
(38%) |
86
(42%) |
97
(47%) |
|
Zometa 4 mg |
200 |
50
(25%) |
58
(29%) |
70
(35%) |
83
(42%) |
|
Overall: |
|
|
|
|
|
|
Aredia 90 mg |
555 |
149(27%) |
209(38%) |
233(42%) |
257
(46%) |
|
Zometa 4 mg |
561 |
145(26%) |
188(34%) |
212(38%) |
248
(44%) |
Table 2.3.7:
K-M Estimated Event Rate (Intent-to-Treat Patients) Over Study Period
|
Treatment |
N |
9 month |
Difference in
Event Rate |
12 month |
p-value |
|
Myeoloma:
Aredia 90 mg |
167 |
44.9% |
4.9% |
47.3% |
0.75 |
|
Zometa 4 mg |
183 |
40.4% |
42.6% |
||
|
Breast
(Chemo): |
|
|
1.5% |
|
0.68 |
|
Aredia 90 mg |
181 |
39.2% |
42.5% |
||
|
Zometa 4 mg |
178 |
38.7% |
42.1% |
||
|
Breaset(Hormonal) |
|
|
6.6% |
|
0.35 |
|
Aredia 90 mg |
207 |
40.6% |
43.5% |
||
|
Zometa 4 mg |
200 |
34.0% |
40.0% |
||
|
Overall: |
|
|
4.0% |
|
0.30 |
|
Aredia 90 mg |
555 |
41.4% |
44.3% |
||
|
Zometa 4 mg |
561 |
37.4% |
41.5% |
The
secondary efficacy endpoints for the study include time to first SRE, skeletal
morbidity rate (SMR), and the overall survival. The time to event “Time” defined
in the protocol is the time period from the date of randomization to the first
date of event or censoring date.
(1) Time to
first SRE
Time
to first SRE is one of the secondary efficacy endpoints. Table 2.3.8 summarizes
the results for study 010.
Table 2.3.8: Time to
first SRE by Stratum and Treatment Arm
|
|
N |
Median (95%CI) |
Hazard
Ratio (95% CI) |
Log-rank
p-value |
|
Myeloma Aredia Zol 4 mg |
167 183 |
301(191,
---) 372(225,
504) |
.97(.71,
1.31) |
0.82 |
|
Breast(CT) Aredia Zol 4 mg |
181 178 |
366(259,
---) 364(249,
---) |
.96(.70,
1.32) |
0.81 |
|
Breast(HT) Aredia Zol 4 mg |
207 200 |
370(258,
---) >380
(---, --) |
.83(.62,
1.12) |
0.22 |
|
Total Aredia Zol 4 mg |
555 561 |
363(273, 399) 373(350, 504) |
.92(.77, 1.09) |
0.31 |
Figure
2.3.1 is the K-M curve for the time to first SRE comparing overall Aredia with
Zol 4 mg arm.
Figure 2.3.1

(2) Time to
Multiple Events:
Because
the patients could continue on the study after the occurrence of a
skeletal-related-event, multiple events might be observed. Analysis for the
time to multiple events (SRE) was conducted by the sponsor. The sponsor used
the Anderson-Gill approaches for the analysis. The analysis results of multiple events analysis of all SRE (-HCM) showed
that there was no difference between the two treatment arms (p=0.076), though
favoring zoledronic acid 4 mg over Aredia 90 mg. Most of the contribution of
this trend was derived from the breast cancer patients with hormonal therapy at
study entry.
Reviewer’s
Comment:
The
Anderson-Gill approach requires the assumption of independent events. This
assumption may not hold in this study because skeletal related events for each
patient might be highly correlated. The
meaning of this analysis result should be cautiously interpreted.
(1) Overall
Survival Time
One
of the safety endpoints in this study was overall survival. Table 2.3.9
summarizes the survival result using the most updated safety database.
Table 2.3.9: Sponsor’s
Analysis for Overall Survival (Safety Population)
|
ITT
Population N=1119 |
Median
(95%CI) (Days) |
Hazard
Ratio |
95%
CI for Hazard Ratio |
Log-rank P-value |
|
Aredia (179/556) |
802(684-802) |
|
|
|
|
Zole
4mg (171/563) |
Not
reached |
0.958 |
0.776-1.182 |
0.55 |
Figure 2.3.2.

Reviewer’s
Comments:
1.
The
survival curves are presented in Figure 2.3.2.
2.
The
median survival time for Aredia arm is 802 days, but the median was not reached
for the Zole 4mg arm. There is no statistically significant difference between
the two treatment arms.
The
primary objective of study 010 was to show non-inferiority in SRE in patients
with myeloma and breast cancer with cancer related bone lesions. SRE, the primary objective for study 010,
was not statistically significant between the arm and the control arm.
Regarding the non-inferiority test, the upper limit of 95% CI for the
difference of SRE event rate between the two treatment arms was 3.7%. A 49% retention of Aredia effect can be
demonstrated.
Study
010 demonstrated marginal efficacy with respect to proportion of SREs of
zoledronate 4mg arm relative to the active control Aredia 30mg arm. The SRE
rate in zoledronate 4mg retained at least 49% of the active control Aredia
effect in the similar patient population as demonstrated in a previous
registration trial under the condition that the current medical practice is
similar to the historical trial.
Bone
metastases are frequently one of the first signs of disseminated disease in
cancer patients. Skeletal complications
due to metastatic disease include bone pain, spinal cord compromise, and
pathological fractures. The purpose of this
clinical study was to determine if therapy with zoledronate is an effective
treatment to decrease the occurrence of skeletal-related complications
associated with metastatic bone disease in patients with cancer other than
breast cancer, multiple myeloma or prostate cancer. Skeletal-related events included radiation therapy to bone
(including the use of radioisotopes), surgery to bone, spinal cord compression,
and pathological fracture events. In
this study, zoledronate treatment in addition to antineoplastic therapy versus
antineoplastic therapy alone was administered to the cancer patients with
metastatic bone lesions.
Study
011 was a randomized, double-blind, multicenter, parallel-group, placebo
controlled Phase III study conducted in a total of 773 patients aged 18 years
or over with ECOG performance status # 2 and bone metastases from
solid tumors other than breast or prostate cancer. Patients were randomized in a double-blind fashion to receive
either zoledronate 4 mg intravenously, or zoledronate 8 mg intravenously, or a
placebo intravenous infusion every three weeks for 12 doses in addition to
their antineoplastic therapy. The
randomized treatment assignment ratio was to be 1:1:1. Patients were to be treated for 36 weeks (9
months). In addition, all patients were
to receive 500 mg of calcium orally and a multivitamin tablet (containing 500
I.U. of vitamin D) daily throughout the study.
Data
used for this review was obtained from the electronic submission dated 8/21/2001. The network path is
"\\Cdsesub1\n21386\N_000\2001_08_21\CRT\datatsets\011" in the
EDR. The following volumes were
reviewed: 1, 92, 94, 97, 98, and 100.
The
primary study objective of this study was to assess the efficacy of zoledronate
therapy (4 or 8 mg) in addition to antineoplastic therapy, compared to
antineoplastic therapy alone, in preventing skeletal-related events in patients
with any cancer with bone metastases other than breast cancer, multiple
meyeloma or prostate cancer. Originally
skeletal-related events (SREs) were defined as radiation therapy to bone, a
change in antineoplastic therapy to treat bone pain, surgery to bone, spinal
cord compression, and pathologic fracture events. This definition of SRE was amended in Amendment 2 (Volume 98 Page
8-18) and excluded the change in antineoplastic therapy to treat bone pain as a
SRE.
The
primary efficacy variable was the proportion of patients with any SRE exclusive
of tumor induced hypercalcemia (TIH or -HCM)).
The
secondary efficacy variables were: (a) proportion of patients with any SRE
inclusive of TIH; (b) time to first occurrence of a SRE; (c) skeletal morbidity
rate, defined as the ratio of the number of occurrences of any SRE, allowing
one event per assessing period (3 weeks), divided by the time at risk for each
patient. Time at risk for each
assessing period is defined as the duration from the start of the assessing
period to the first SRE. If there is no
SRE for an assessing period, the whole duration of the assessing period was
considered at risk. Time at risk during
the study was the sum of time at risk of each assessing period of the study.
(d) Time to progression to bone metastases; (e) time to overall progression of
disease; (f) quality of life index (FACT-G), performance status (ECOG), Pain
(BPI pain composite score), and analgesic scores; (g) biochemical markers; and
(h) objective bone lesion response.
Reviewer’s
Comments:
FDA
reviewer of the IND protocol had conveyed to the sponsor that the if the
drop-out rate is relatively high, then the primary endpoint, SRE proportion
estimate may be biased and had also suggested that the time to the first SRE be
used as the co-primary endpoint.
This
trial was designed to have 80% power to detect a 16% difference in the
proportion of patients reporting any SRE during the first 9 months of the trial
between the two dose levels (4 mg and 8 mg) of zoledronate and placebo. Based on the Bonferroni’s adjustment, the
samples size was calculated, assuming a 48% incidence rate on placebo; a 32%
incidence rate on either dose level of zoledronate, with an overall type I
error rate of 0.05 (two-sided). The total sample size was determined to be 570
patients (190 on each arm). It was
recommended that 600 patients be enrolled allowing for a 5% noise included in
the intent-to-treat population.
However, the sample size was increased (Amendment 4, Volume 98, Page
8-33) that at least 700 patients would be enrolled in order to obtain 663
patients (221 patients per treatment arm).
It was stated that the amendment was based on the higher than expected
overall drop-out rate of 40% and the lower than expected SRE rate of less than
30%. The sample size was modified
assuming to have 80% power to detect a 14% difference in the proportion of SREs
during the first 9 months of the trial between the two dose levels of
zoledronate and placebo (Bonferroni adjustment for multiple comparisons,
overall type I error rate=0.05).
Reviewer’s
Comments:
1.
The
sample size calculations were based on that zoledronate would be considered
more efficacious than placebo if either of the two comparisons (4 mg versus
placebo or 8 mg versus placebo) was statistically significant at a 2-sided
p-value < 0.025.
2.
During
the study, the design was amended (Amendment 5) to treat all patients on study
in the 8 mg group at 4 mg dose level because of the observed renal toxicity
with 8 mg group. In lieu of this, in
the Amendment 6 (Volume 98, Page 8-54), it was stated that zoledronate 4 mg
will be considered more efficacious than placebo if the comparison for the
primary efficacy outcome is statistically significant at 0.05 level (2-sided)
favoring zoledronate 4 mg. It should be
noted that the original design and calculation of sample size was based on
comparing 4 mg versus placebo group at 0.025 level. Dropping a treatment arm (in this case 8 mg group) could
potentially inflate the overall type I error rate. (Reference: Tsong, Y, Hung HMJ,
Wang SJ, et. al.. Dropping a treatment arm in clinical trial with multiple
arms, JSM Proceedings, 1997).
The
randomization was stratified by site of cancer 'lung cancer' versus 'other
solid tumor' (Appendix 5, Volume 100, page 8-319).
There
was no planned interim analysis for this study. However, at an interim time
point the 8 mg zoledronate arm was dropped due to renal toxicity concerns. The
sponsor claimed there was no efficacy analyses conducted at the interim look.
The primary efficacy endpoint of proportion of patients with SREs per protocol would be compared between treatment groups using a Cochran-Mantel-Haenszel (CMH) test statistic. 95% confidence intervals by treatment group within each stratum for the proportion of patients reporting SRE exclusive of TIH would be presented. Zoledronate would be considered more efficacious than placebo if either of the two comparisons of the primary efficacy outcome is statistically superior at a two-sided p-value < 0.025. In Amendment 2 (Volume 98, page 8-20) the primary analysis was modified to state that the analysis of the primary endpoint at 9 months would be the primary analysis and that the last observation of each patient before the time point would be carried forward to the respective time points.
The
secondary efficacy endpoint of proportion of patients with any SRE inclusive of
TIH would be compared between the treatment groups using CMH statistic and 95%
confidence intervals by treatment group within each stratum for the proportion
of patients reporting any SRE inclusive of TIH would be presented.
Time
from randomization to the first occurrence of any SRE, inclusive and exclusive
of TIH would be compared between the treatment groups, using stratified
survival analysis methods, including Kaplan-Meier product-limit estimates of
the survival functions, and the log-rank test.
Death not related to SRE would be considered as censored
observation. Multiple events analysis,
allowing one event every assessing period would be explored using Anderson-Gill
approach.
Skeletal
morbidity rate (SMR) will be compared between the treatment groups using CMH
test statistic with modified ridit scores.
Time
to the progression of bone metastases would be compared between the treatment
groups using log-rank test. Time to
overall progression of disease would be compared between the treatment groups
using stratified log-rank test statistic.
FACT-G-total
score is defined as the sum of the 4 subscales (physical, functional, social,
and emotional). Change from baseline
FACT-G-total scores and the 4 subscales would be compared between the treatment
groups using analysis of coavariance with baseline value as covariate and
treatment group and disease population as factors, at 3, 6, and 9 months. The mean of the two BPI pain composite
scores and two analgesic use for each 3 month interval would be used for the
analysis of BPI pain score and analgesic use, respectively. Change from baseline in mean BPI composite score
would be compared between the treatment groups using analysis of covariance
with baseline value as a covariate and treatment group and disease population
as factors at 3, 6, and 9 months.
Change from baseline in mean analgesic use and performance status would
be compared between the treatment groups using CMH test statistic with the
modified ridit scores at 3, 6, and 9 months.
Reviewer’s
Comments:
1.
Early
dropouts and missing assessments were not considered in the above planned
analyses.
2.
The
infusion time was amended (Amendment 3) from 5 minutes to 15 minutes during the
study.
3.
After
the enrollment was completed in all the three treatment arms, the dose was
reduced in the 8 mg arm to 4 mg (Amendment 5) because of renal toxicity. In this Amendment it was also stated that
the 8/4 mg arm would not be evaluated for efficacy. However, it should be noted that by the time of this Amendment,
majority of the patients had completed the study treatment phase (9 months) or
had dropped out of the study.
A
total of 773 patients were randomized as follows: 257 patients were randomized
to the 4 mg zoledronic acid group, 266 patients to the 8 mg zoledronic acid
group, and 250 patients to the placebo group.
Eligible patients were randomized into two groups: patients with
non-small cell lung cancer (NSCLC) and patients with all other types of solid
tumor cancers except breast and prostate.
Several patients in each treatment group were randomized to the
incorrect stratum as follows: 35 patients with small cell lung cancer were
randomized into the NSCLC stratum, instead of other solid tumor stratum (12 in
the 4 mg group, 10 in the 8/4 mg group, and 13 in the placebo group); 3
patients with NSCLC were randomized into the other solid tumors stratum (one
patient in each treatment group). It is
reported that 7 patients did not receive treatment with the study medication,
one of these 7 patients died prior to receiving any study medication. One patient in the 4 mg group was found to
have no evidence of skeletal metastases on the radiographic evaluations
performed at study entry and the films for another patient on 8/4 mg group were
lost in transit and therefore had no confirmed radiographic evidence of bone
metastases. Ten patients, 2 in 4 mg
group, 1 in 8/4 mg group, and 7 in the placebo group were unblinded at the
study sites. All were discontinued from
the study. The following Table 2.4.1a
describes the baseline characteristics as presented by the sponsor in the per
protocol or safety population (Sponsor’s Table 7-3, page 8-52, Volume 92).
Table 2.4.1a: Baseline
Characteristics (Sponsor’s Analysis – Safety Population)
|
|
Total |
||
|
|
Zol 4 mg N=254 |
Zol 8/4 mg N=265 |
Placebo N=247 |
|
Age (years) |
|
|
|
|
N |
254 |
265 |
247 |
|
Mean
" SD |
62.3"10.60 |
60.8"10.46 |
62.3"10.87 |
|
Median |
63.5 |
62.0 |
64.0 |
|
Age
n (%) |
|
|
|
|
# 60 |
106
(41.7%) |
124
(46.8%) |
98
(39.7%) |
|
>
60 |
148
(58.3%) |
141
(53.2%) |
149
(60.3%) |
|
Sex n (%) |
|
|
|
|
Male |
158
(62.2%) |
186
(70.2%) |
159
(64.4%) |
|
Female |
96
(37.8%) |
79
(29.8%) |
88
(35.6%) |
|
Race n (%) |
|
|
|
|
Caucasian |
226
(89.0%) |
237
(89.4%) |
223
(90.3%) |
|
Black |
15
(5.9%) |
15
(5.7%) |
12
(4.9%) |
|
Other |
13
(5.1%) |
13
(4.9%) |
12
(4.9%) |
|
Weight (kg) |
|
|
|
|
N |
252 |
262 |
245 |
|
Mean
" SD |
72.8"15.23 |
74.3"16.91 |
71.6"16.04 |
|
Median |
72.0 |
73.0 |
69.8 |
|
Primary site of cancer n
(%) |
|
|
|
|
Lung |
124
(48.8%) |
134
(50.6%) |
123
(49.8%) |
|
Other |
|
|
|
|
Renal
cell carcinoma |
27
(10.6%) |
28
(10.6%) |
19
(7.7%) |
|
Cancer
unknown primary |
15
(5.9%) |
14
(5.3%) |
14
(5.7%) |
|
Thyroid |
2
(0.8%) |
5
(1.9%) |
4
(1.6%0 |
|
Head
and neck |
6
(2.4%) |
7
(2.6%) |
4
(1.6%) |
|
Other |
80
(31.5%) |
77
(29.1%) |
83
(33.6%) |
|
Prior type of therapy |
|
|
|
|
Chemotherapy |
207
(81.5%) |
212
(80.0%) |
197
(79.8%) |
|
Hormonal |
3
(1.2%) |
1
(0.4%) |
2
(0.8%) |
|
Missing |
44
(17.3%) |
52
(19.6%) |
48
(19.4%) |
|
Previous SRE n (%) |
|
|
|
|
Yes |
166
(65.4%) |
180
(67.9%) |
179
(72.5%) |
|
No |
88
(34.6%) |
85
(32.1%) |
68
(27.5%) |
|
Serum creatinine n (%) |
|
|
|
|
Normal
(< 1.4 mg/dL) |
233
(91.7%) |
232
(87.5%) |
220
(89.1%) |
|
Abnormal
($ 1.4 mg/dL) |
18
(7.1%) |
33
(12.5%) |
25
(10.1%) |
|
Missing |
3
(1.2%) |
0
(0.0%) |
2
(0.8%) |
|
Time from initial diagnosis
of cancer to bone metastases (month) |
|
|
|
|
N |
254 |
265 |
247 |
|
Mean
" SD |
20.3"46.58 |
15.5"39.50 |
17.2"33.24 |
|
Median |
3.8 |
2.4 |
2.5 |
|
Time from bone metastases
to Visit 2 (month) |
|
|
|
|
N |
254 |
265 |
247 |
|
Mean
" SD |
4.7"7.69 |
4.9"7.90 |
5.1"9.52 |
|
Median |
1.6 |
1.8 |
1.8 |
|
ECOG status n (%) |
|
|
|
|
ECOG
0-1 |
211
(83.1%) |
218
(82.3%) |
215
(87.0%) |
|
ECOG
$ 2 |
42
(16.5%) |
45
(17.0%) |
32
(13.0%) |
|
Missing |
1
(0.4%) |
2
(0.8%) |
0
(0.0%) |
|
Analgesic score n (%) |
|
|
|
|
0 |
30
(11.8%) |
27
(10.2%) |
24
(9.7%) |
|
1 |
39
(15.4%) |
44
(16.6%) |
38
(15.4%) |
|
2 |
6
(2.4%) |
8
(3.0%) |
5
(2.0%) |
|
3 |
93
(36.6%) |
86
(32.5%) |
76
(30.8%) |
|
4 |
86
(33.9%) |
100
(37.7%) |
103
(41.7%) |
|
Missing |
0
(0.0%) |
0
(0.0%) |
1
(0.4%) |
|
BPI composite pain score |
|
|
|
|
N |
234 |
245 |
227 |
|
Mean
" SD |
3.6"2.20 |
3.3"1.94 |
3.4"1.99 |
|
Median |
3.5 |
3.3 |
3.3 |
|
FACT-G total score |
|
|
|
|
N |
230 |
241 |
227 |
|
Mean
" SD |
70.1"15.21 |
69.3"16.85 |
70.8"17.73 |
|
Median |
71.0 |
69.0 |
71.2 |
Table 2.4.1b: Baseline Characteristics (FDA Analysis
– ITT population)
|
|
NSCLC |
All Others Tumors |
Total |
||||||
|
|
Zol 4 mg N=134 |
Zol 8/4 mg N=139 |
Placebo N=130 |
Zol 4 mg N=123 |
Zol 8/4 mg N=127 |
Placebo N=120 |
Zol 4 mg N=257 |
Zol 8/4 mg N=266 |
Placebo N=250 |
|
Age (years) |
|
|
|
|
|
|
|
|
|
|
N |
134 |
139 |
130 |
123 |
127 |
120 |
257 |
266 |
250 |
|
Mean
" SD |
63.2"0.8 |
61.9"0.9 |
62.5"0.9 |
61.0"1.1 |
59.6"0.9 |
62.5"1.1 |
62.0"0.7 |
60.8"0.6 |
62.3"0.7 |
|
Median |
64.0 |
63.0 |
64.0 |
60.0 |
63.0 |
63.0 |
62.0 |
63.5 |
|
|
Age n (%) |
|
|
|
|
|
|
|
|
|
|
# 60 |
54
(40.3%) |
60
(43.2%) |
51
(39.2%) |
55
(44.7%) |
65
(51.1%) |
48
(40.0%) |
109
(42.4%) |
125
(47.0%) |
99
(39.6%) |
|
>
60 |
80
(59.7%) |
79
(56.8%) |
79
(60.8%) |
68
(55.3%) |
62
(48.9%) |
72
(60.0%) |
148
(57.6%) |
141
(53.0%) |
151
(60.4%) |
|
Sex n (%) |
|
|
|
|
|
|
|
|
|
|
Male |
89
(66.4%) |
99
(71.2%) |
82
(63.1%) |
71
(57.7%) |
87
(68.5%) |
80
(66.7%) |
160
(62.3%) |
186
(69.9%) |
162
(64.8%) |
|
Female |
45
(33.6%) |
40
(28.8%) |
48
(36.9%) |
52
(42.3%) |
40
(31.5%) |
40
(33.3%) |
97
(37.7%) |
80
(30.1%) |
88
(35.2%) |
|
Race n (%) |
|
|
|
|
|
|
|
|
|
|
Caucasian |
121
(90.3%) |
123
(88.5%) |
119
(91.5%) |
108
(87.8%) |
115
(90.6%) |
107
(89.2%) |
229
(90.2%) |
238
(89.5%) |
226
(90.4%) |
|
Black |
3 (2.2%) |
8 (5.8%) |
5 (3.6%) |
12
(9.8%) |
7 (5.5%) |
7 (5.8%) |
12
(4.7%) |
15
(5.6%) |
12
(4.8%) |
|
Other |
10
(6.5%) |
8 (5.8%) |
6 (4.6%) |
3 (2.4%) |
5 (3.9%) |
6 (5.0%) |
13
(5.1%) |
13
(4.9%) |
12
(4.8%) |
|
Weight (kg) |
|
|
|
|
|
|
|
|
|
|
N |
133 |
137 |
128 |
121 |
125 |
119 |
254 |
262 |
247 |
|
Mean
" SD |
72.8"1.3 |
74.0"1.5 |
70.0"1.3 |
72.7"1.5 |
74.7"1.5 |
73.3"1.6 |
72.7"1.0 |
74.3"1.0 |
71.6"1.0 |
|
Median |
72.2 |
73.0 |
68.8 |
71.4 |
73.0 |
72.0 |
72.0 |
73.0 |
69.8 |
|
Previous SRE |
|
|
|
|
|
|
|
|
|
|
Yes |
44
(33.1) |
47
(33.8) |
32
(24.8) |
44
(36.1) |
38
(30.3) |
36
(30.3) |
88
(34.5) |
85
(32.1) |
68
(27.4) |
|
No |
89
(66.9) |
92
(66.2) |
97
(75.2) |
78
(63.9) |
88
(69.7) |
83
(69.7) |
167
(65.5) |
180
(67.9) |
180
(72.6) |
|
Serum creatinine |
|
|
|
|
|
|
|
|
|
|
Normal
(< 1.4 mg/dL) |
129
(96.3%) |
125
(89.9%) |
125
(96.1%) |
110
(89.4%) |
108
(85.0%) |
100
(83.3%) |
239
(93.0%) |
233
(87.6%) |
225
(90.0%) |
|
Abnormal
($ 1.4 mg/dL) |
5 (3.7%) |
14
(10.1%) |
5 (3.9%) |
13
(10.6%) |
19
(10.6%) |
20
(16.7%) |
18
(7.0%) |
33
(12.4%) |
25
(10.0%) |
|
Time from initial diagnosis
of cancer to bone metastases (month) |
|
|
|
|
|
|
|
|
|
|
N |
134 |
< | |||||||