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`CENTER FOR DRUG EVALUATION AND
`RESEARCH
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`APPLICATION NUMBER:
`022410Orig1s000
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`STATISTICAL REVIEW(S)
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`U.S. Department of Health and Human Services
`Food and Drug Administration
`Center for Drug Evaluation and Research
`Office of Translational Science
`Office of Biostatistics
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`Statistical Review and Evaluation
` CARCINOGENICITY STUDIES
`
`NDA 22-410
`Suboxone (Buprenorphine and Naloxone)
`Two Year Carcinogenicity in Rats
`Sponsor: Reckitt & Colman Products Limited, Danson Lane, Hull,
`HU87DS, UK
`Test facility:
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`Submission: Electronic, Dated: Dec. 9, 2003 (Sponsor’s date of issue)
`Data: No data were submitted
`Standard
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`Division of Biometrics -6
`Mohammad Atiar Rahman, Ph.D.
`Karl Lin, Ph.D.
`
`Division of Anesthesia, Analgesia, and Rheumatology Products
`Elizabeth Bolan, Ph.D.
`Mathew Sullivan
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`Carcinogenicity, Dose response
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`IND/NDA Number:
`Drug Name:
`Indication(s):
`Applicant:
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`Documents Reviewed:
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`Review Priority:
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`Biometrics Division:
`Statistical Reviewer:
`Concurring Reviewer:
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`Medical Division:
`Reviewing Pharmacologist:
`Project Manager:
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`Keywords:
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`(b) (4)
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`NDA 22-423 Ciltyri Page 2 of 7
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`Table of Contents
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`1......................................................................................................................................... Background
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`2................................................................................................................................................ Design
`2.1.
`Sponsor's analyses.............................................................................................................................3
`2.1.1. Survival analysis .................................................................................................................3
`2.1.2. Tumor data analysis ............................................................................................................3
`Reviewer's analyses...........................................................................................................................4
`2.2.1. Survival analysis .................................................................................................................4
`2.2.2. Tumor data analysis ............................................................................................................4
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`2.2.
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`3.............................................................................................................................................Summary
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`4..........................................................................................................................................References:
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`NDA 22-410 Suboxon Page 3 of 7
`1. Background
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`In this submission the sponsor included a report of an animal carcinogenicity study in rats. This study was
`intended to assess the carcinogenic potential of suboxone (Buprenorphine and Naloxon) in rats when
`administered orally through dietary mixture at appropriate drug levels for about 104 weeks. Results of this
`review have been discussed with the reviewing pharmacologist Dr. Bolan.
`
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`
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`2. Design
`
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`Two separate experiments were conducted, one in males and one in females. In each of these two
`experiments there were three treated groups and two identical control groups. Two hundred and sixty OFA
`Alpk:APfSD rats of each sex were randomly allocated to treated and control groups in equal size of 52
`animals. The dose levels for treated groups were 100, 450, and 1800 ppm. In this review these dose groups
`would be referred to as the low, medium, and high dose group, respectively. The two controls will be referred
`to as Control 1 and Control 2. The controls received the vehicle (CT1 diet).
`
`Prior to the start of the study, all rats were examined to ensure that they were normal. The cageside
`observations that included recording any changes in clinical condition or behavior were made twice daily.
`Detailed clinical observations, included the finding of abnormalities were recorded at least weekly, at the
`same time that the bodyweights were recorded, where applicable.
`
`All tissues of animals found dead or killed inter currently, all animals in both control groups and the high
`dose group, all gross lesions, tumors, suspected tumors and associated tissues were submitted for histology.
`In addition, the following tissues from the mid and low dose groups were submitted for histology: males -
`testes, pituitary gland, liver, spleen, adrenal glands, eye, lachrymal gland, seminal vesicles and voluntary
`muscle, and females – adrenal glands, uterus, pituitary gland, mammary gland, liver, spleen and eye.
`
`
`2.1.
`
`Sponsor's analyses
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`Survival analysis
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`2.1.1.
`
`Survival function of each treatment group was estimated using the Kaplan-Meier product limit method for
`each sex. Mortalities that were the result of animals killed in moribund conditions or at scheduled termination
`were considered to be censored observations. Intergroup comparisons of mortality, comparing each
`treatment group with the pooled control group, and an overall test for dose response relationship were
`performed using the logrank test.
`
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`Sponsor’s findings: Sponsor’s analysis showed that there were no statistically significant differences in
`survival in the individual group comparisons. Overall, there was a statistically significant dose response
`relationship (p<0.05) in mortality for the males. Female survival in the 450 and 1800 ppm groups was
`statistically significantly lower (p<0.05 and p<0.01, respectively) in comparison with the control group.
`Survival for the females in the 100 ppm group was also slightly lower than the controls, but this difference
`did not achieve statistical significance. Overall, there was a statistically significant dose response relationship
`(p<0.01) in mortality for the females.
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`2.1.2. Tumor data analysis
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`Tests for dose response relationships were performed using the Cochran-Armitage test (Gart et al 1986). The
`pairwise comparisons of incidence rates of tumor types in each treated group with the pooled control group
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`NDA 22-410 Suboxon Page 4 of 7
`were performed using the Fisher’s Exact test. In addition, age adjusted tests were performed using a
`prevalence analysis (assuming tumors were incidental), a death rate analysis (assuming all tumors were
`observed in a fatal context) and a combined analysis allowing for the observed context as described in Peto et
`al (1980). All statistical tests were two-sided.
`
`Adjustment for the multiplicity: The sponsor did not mention of any method for multiple testing
`adjustment.
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`Sponsor’s findings: The sponsor’s analysis showed that the incidence of unilateral leydig cell adenomas
`reached statistical significance only in the 1800 ppm group, (p=0.008) in male rats. The increased incidence
`of unilateral leydig cell adenomas in animals in the 1800 ppm group was also above that for historical
`controls. The sponsor’s analysis also showed that the incidence of bilateral leydig cell adenomas reached
`statistical significance (p=0.001) in all groups administered suboxone in male rats. The increased incidence of
`bilateral leydig cell adenomas was also above that for historical controls in all groups administered suboxone.
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`2.2.
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`Reviewer's analyses
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`Survival analysis
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`
`To verify some of the sponsor’s findings and to perform additional analysis suggested by the reviewing
`pharmacologist, this reviewer performed some independently analyses. Data for this reviewer’s analyses were
`taken from the sponsor’s summary tables given in their final report (submitted electronically). It may be
`mentioned that the raw data were not available and were never submitted to the agency.
`
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`2.2.1.
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`Since the raw data were not available, this reviewer could not perform any survival analysis of the animals.
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`2.2.2. Tumor data analysis
`
`Since the raw data were not available a formal and complete analysis of the tumor incidence was not possible.
`On the suggestion of the reviewing pharmacologist, this reviewer only performed a brief analysis of the
`following selected tumor types.
`
`Selected tumor types: (1) Unilateral benign Leydig cell adenoma of the testes, (2) Bilateral benign Leydig cell
`adenoma of the testes, (3) Adenoma of the uterus, (4) Adenocarcinoma of the uterus, and (5) Large granular
`lymphocyte leukemia of the lymphoreticular system (male and female). The pharmacologist also wanted to
`perform analysis on combined incidences of the uterine adenomas and adenocarcinomas.
`
`Noting that the two control groups were identical, in this reviewer’s analysis the two control groups were
`combined together to form a single control (pooled control). This kind of pooling increases the power of the
`test and reduces the dimension of the multiplicity of testing.
`
`For the tumor data analyses, this reviewer performed dose response relationship tests (wherever it was possible)
`and pairwise comparisons of pooled control with each of the treated groups using the Cochran-Armitage test
`(1955).
`
`Multiple testing adjustment: For the adjustment of multiple testing of dose response relationship, the FDA
`guidance for the carcinogenicity study design and data analysis suggests the use of test levels α=0.005 for
`common tumors and α=0.025 for rare tumors for a submission with two species, and a significance level
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`NDA 22-410 Suboxon Page 5 of 7
`α=0.01 for common tumors and α=0.05 for rare tumors for a submission with one species study in order to
`keep the false-positive rate at the nominal level of approximately 10%. A rare tumor is defined as one in which
`the published spontaneous tumor rate is less than 1%. For multiple pairwise comparisons of treated group
`with control the FDA guidance the suggested the use of test levels α=0.01 for common tumors and α=0.05
`for rare tumors, in order to keep the false-positive rate at the nominal level of approximately 10% for both
`submissions with two or one submission. In any carcinogenicity study review by this agency, the above test
`levels are generally used for the final interpretation of the statistical findings.
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`Reviewer’s findings: Following table shows this reviewer’s analyses.
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`The Incidence Rates and P-Values for Dose Response Relationship or Pairwise Comparisons*
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` Pooled _____________P_Value_____________
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` Cont Low Med High Dose Cont. Cont. Cont.
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`Sex Organ Name Tumor Name N=104 N=52 N=52 N=52 Resp vs. L vs. M vs. H
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`ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ
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` Male Testis Unilateral 9/104 10/52 7/52 14/52 0.0054* 0.0527 0.3430 0.0032*
`
` Leydig cell adenoma
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` Bilateral 1/104 11/52 18/52 19/52 <0.001* <0.001* <0.001* <0.001*
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` Leydig cell adenoma
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` Lymphoreticular Large granular 7/104 9/52 8/52 6/52 0.1410 0.0410 0.0776 0.2329
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` system lymphocyte leukaemia
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`Female Lymphoreticular Large granular 14/104 6/52 12/52 11/52 0.0608 0.4749 0.1000 0.1578
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` system lymphocyte leukaemia
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` Uterus Adenoma 1/104 1/52 2/52 1/52 0.2809 0.5570 0.2578 0.5570
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` Adenocarcinoma 12/104 11/52 10/52 12/52 0.0408 0.0892 0.1455 0.0520
`
` Adenoma + 13/104 12/52 12/52 13/52 0.0262 0.0733 0.0733 0.0425
`
` Adenocarcinoma#
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` *Data for this analysis were taken from sponsor’s Table: 18 .
`
`#Due to the lack of original data, these combined incidence rates for adenoma and adenocarcinoma were calculated by simply adding the
`number of animals with adenoma and number of animals with adenocarcinoma in two previous lines. This calculation may be inaccurate
`due to the fact that we were supposed to count each animals once either with adenoma or with adenocarcinoma, but due to simple
`addition of numbers we might have double counted some animals having both adenoma and adenocarcinoma.
`
`Based on the above criterion for multiple testing adjustment, the incidence of testis/unilateral leydig cell
`adenoma and testis/bilateral leydig cell adenoma in male rats were considered to have statistically significant
`positive dose response relationships. Also in male rats the increased incidence of testis/unilateral leydig cell
`adenoma in high dose group and testis/bilateral leydig cell adenoma in all treated groups were considered to
`be statistically significant compared to the pooled control.
`
`
`3. Summary
`
`
`In this submission the sponsor included a report of an animal carcinogenicity study in rats. This study was
`intended to assess the carcinogenic potential of suboxone (Buprenorphine and Naloxon) in rats when
`administered orally through dietary mixture at appropriate drug levels for about 104 weeks. Two separate
`experiments were conducted, one in males and one in females. In each of these two experiments there were
`three treated groups and two identical control groups. Two hundred and sixty OFA Alpk:APfSD rats of each
`sex were randomly allocated to treated and control groups in equal size of 52 animals. The dose levels for
`treated groups were 100, 450, and 1800 ppm. The controls received the vehicle (CT1 diet).
`
`

`

`
`
`
`
`NDA 22-410 Suboxon Page 6 of 7
`
`Prior to the start of the study, all rats were examined to ensure that they were normal. The cage side
`observations that included recording any changes in clinical condition or behavior were made twice daily.
`Detailed clinical observations, included the finding of any abnormalities were recorded at least weekly, at the
`same time that the bodyweights were recorded, where applicable.
`
`All tissues of animals found dead or killed inter currently, all animals in both control groups and the high
`dose group, all gross lesions, tumors, suspected tumors and associated tissues were submitted for histology.
`In addition, the following tissues from the mid and low dose groups were submitted for histology: males -
`testes, pituitary gland, liver, spleen, adrenal glands, eye, lachrymal gland, seminal vesicles and voluntary
`muscle, and females – adrenal glands, uterus, pituitary gland, mammary gland, liver, spleen and eye.
`
`In this review, the phrase "dose response relationship" refers to the linear component of the effect of treatment,
`and not necessarily to a strictly increasing or decreasing mortality or tumor rate as dose increases.
`
`Since the sponsor never submitted the tumor data to the agency and also was not available to the sponsor, a
`formal and complete analysis of the tumor incidence was not possible. On the suggestion of the reviewing
`pharmacologist, this reviewer only performed a brief analysis of the following selected tumor types.
`
`Selected tumor types: (1) Unilateral benign Leydig cell adenoma of the testes, (2) Bilateral benign Leydig cell
`adenoma of the testes, (3) Adenoma of the uterus, (4) Adenocarcinoma of the uterus, and (5) Large granular
`lymphocyte leukemia of the lymphoreticular system (male and female). The pharmacologist also wanted to
`perform analysis on combined incidences of the uterine adenomas and adenocarcinomas.
`
`Noting that the two control groups were identical, in this reviewer’s analysis the two control groups were
`combined together to form a single control (pooled control). This kind of pooling increases the power of the
`test and reduces the dimension of the multiplicity of testing.
`
`Tests showed statistically significant positive dose response relationship in the incidence of testis/unilateral
`leydig cell adenoma and testis/bilateral leydig cell adenoma in male rats. Also in male rats, the pairwise
`comparisons showed statistically significant increased incidence of testis/unilateral leydig cell adenoma in
`high dose group and testis/bilateral leydig cell adenoma in all treated groups compared to the pooled control.
`
`
` Mohammad Atiar Rahman, Ph.D.
` Mathematical Statistician
`Concur: Karl Lin, Ph.D.
` Team Leader, Biometrics-6
`
`cc:
`Archival NDA 22-410 Suboxon
`Dr. Bolan Dr. Machado
`Mr. Sullivan Dr. Lin
` Dr. Rahman
` Ms. Patrician
`
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`

`

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`NDA 22-410 Suboxon Page 7 of 7
`4. References:
`
`1. Armitage, P (1955), "Tests for Linear Trends in Proportions and Frequencies", Biometrics, 11, 375-
`386.
`2. Gart, J.J., Krewski, D., Lee, P.N., Tarone, R.E., and Wahrendorf, 1., Statistical Methods in Cancer
`Research: The Design and Analysis of Long- Term Animal Experiments, IARC Scientific
`Publications, VoL 3, No. 79, Oxford University Press, New York (1986).
`3. Peto, R., M.C. Pike, N.E. Day, R.G. Gray, P.N. Lee, S. Parish, J. Peto, Richards, and J.Wahrendorf,
`“Guidelines for sample sensitive significance test for carcinogenic effects in long-term animal
`experiments”, Long term and short term screening assays for carcinogens: A critical appraisal,
`International agency for research against cancer monographs, Annex to supplement, World Health
`Organization, Geneva, 311-426, 1980.
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`---------------------------------------------------------------------------------------------------------------------
`This is a representation of an electronic record that was signed electronically and
`this page is the manifestation of the electronic signature.
`---------------------------------------------------------------------------------------------------------------------
` /s/
`---------------------
`Atiar Rahman
`5/21/2009 09:55:02 AM
`BIOMETRICS
`
`Karl Lin
`5/26/2009 10:22:03 AM
`BIOMETRICS
`Concur with review
`
`