Federal Register, Volume 78 Issue 52 (Monday, March 18, 2013)

[Federal Register Volume 78, Number 52 (Monday, March 18, 2013)]
[Notices]
[Pages 16681-16684]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-06145]

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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

[Docket No. FDA-2013-N-0222]

International Conference on Harmonisation; Proposed Change to
Rodent Carcinogenicity Testing of Pharmaceuticals; Request for Comments

AGENCY: Food and Drug Administration, HHS.

ACTION: Notice; request for comments.

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SUMMARY: The Food and Drug Administration (FDA or the Agency) is
considering a proposed change to the International Conference on
Harmonisation (ICH) Sl guidance on rodent carcinogenicity testing. The
goal of this potential change is to introduce a more comprehensive and
integrated approach to address the risk of human carcinogenicity of
small molecule pharmaceuticals, and to define conditions under which 2-
year rodent carcinogenicity studies add value to that assessment. The
basis of this proposed change is the retrospective analyses of several
datasets that reflect three decades of experience with such studies.
The datasets suggest that knowledge of certain pharmacologic and
toxicologic data can sometimes provide sufficient information to
anticipate the outcome of 2-year rodent studies and their potential
value in predicting the risk of human carcinogenicity of a given
pharmaceutical. FDA is requesting public comment regarding a proposed
change in approach to carcinogenicity assessment, on the prospective
evaluation period intended to test this new approach, and on the
proposed weight-of-evidence factors for carcinogenicity assessment.

DATES: Submit electronic or written comments on the proposed change by
May 17, 2013.

ADDRESSES: Submit electronic comments on the proposed change to http://www.regulations.gov. Submit written comments to the Division of Dockets
Management (HFA-305), Food and Drug Administration, 5630 Fishers Lane,
rm. 1061, Rockville, MD 20852.

FOR FURTHER INFORMATION CONTACT: Todd Bourcier, Center for Drug
Evaluation and Research, Food and Drug Administration, 10903 New
Hampshire Ave., Bldg. 22, rm. 3102, Silver Spring, MD 20993-0002, 301-
796-1179.

SUPPLEMENTARY INFORMATION:

I. Background

FDA is considering a change in the current ICH S1 guidance on
rodent carcinogenicity testing.\1\ The goal of this potential change is
to introduce a more comprehensive and integrated approach to address
the risk of human carcinogenicity of small molecule pharmaceuticals,
and to define conditions under which 2-year rodent carcinogenicity
studies add value to that assessment.
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\1\ See the ICH S1 guidance documents, ``S1A The Need for Long-
Term Rodent Carcinogenicity Studies of Pharmaceuticals'' (ICH S1A),
``S1B Testing for Carcinogenicity of Pharmaceuticals'' (ICH S1B),
and ``S1C(R2) Dose Selection for Carcinogenicity Studies of
Pharmaceuticals'' (ICH S1C), available on the Internet at http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm or http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/default.htm.
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Datasets evaluated by the ICH S1 expert working group (S1 EWG)
suggest that knowledge of pharmacologic targets and pathways together
with toxicological and other data can, in certain cases, provide
sufficient information to anticipate the outcome of 2-year rodent
studies and their potential value in predicting the risk of human
carcinogenicity of a given pharmaceutical. It is hypothesized that
consideration of this information can provide sufficient information to
conclude that a given pharmaceutical in certain cases presents a
negligible risk or, conversely, a likely risk of human carcinogenicity
without conducting a 2-year rodent study. It is envisioned that
sponsors of such pharmaceuticals would provide drug regulatory agencies
(DRAs) a carcinogenicity assessment document (CAD) that could justify a
``waiver request'' that would seek to omit the conduct of 2-year rodent
studies. The CAD would address the overall carcinogenic risk of the
investigational drug as predicted by the endpoints discussed in this
document and a rationale for why the conduct of 2-year rodent studies
would or would not add value to that assessment.
Prospective evaluation of this proposed hypothesis is necessary to
justify proceeding with revision of the ICH S1 guidance. A prospective
evaluation period would be sought wherein sponsors would be requested
to submit CADs to DRAs for all investigational pharmaceuticals with
ongoing or planned 2-year rodent studies. DRAs from each region would
independently review the submitted assessments to evaluate the degree
of concordance with sponsors and between regulatory regions. During
this prospective evaluation period, the waiver requests would not to be
granted and rather are intended solely for gathering experience and
hypothesis testing. Submitted assessments would be compared to the
outcome of the 2-year rodent studies to evaluate the accuracy and
relevance of the predictions to the actual experimental results.
Experience from this prospective evaluation period is considered
critical to informing the S1 EWG's efforts in revising the current
paradigm of assessing the carcinogenicity of small molecules as
described in the ICH S1 guidance. FDA is requesting public comment
regarding the proposed change in approach to carcinogenicity
assessment, on the prospective evaluation period intended to test this
new approach, and on the weight-of-evidence (WOE) factors proposed for
inclusion in CADs.

II. Past Experience With Carcinogenicity Assessment

The strategy of testing for carcinogenic potential was the first
safety topic addressed by ICH. The main topics were the need to conduct
a study (ICH S1A), the selection criteria for the rodent species (ICH
S1B), and the criteria for selecting the maximum dose (ICH S1C). During
the discussion in that period, the relevance of the lifetime
carcinogenicity studies in rats and mice was already highly debated,
but in the absence of an alternative, the outcome of the negotiations
did not really change the basic strategy of testing pharmaceuticals for
human use in two rodent species. A proposal to not use the mouse as a
second species did not receive sufficient support, although it paved
the way to introduce transgenic mice with a 6- to 9-month treatment as
an appropriate alternative (ICH S1B).
In the following years, considerable resources have been spent to
evaluate the approaches using the transgenic mice (Ref. 1). Also, other
models and approaches received attention, especially the possibility to
predict the outcome of carcinogenicity studies on the basis of the
results of 3- to 6-month studies (Ref. 2).

[[Page 16682]]

In this framework, researchers from a U.S.-based company started a
project with 60 company-owned and marketed compounds (Ref. 3) with the
outcome that a negative histopathology result in rats (i.e., no
evidence of hyperplasia in any organ) might be predictive for the
absence of tumors in a 2-year study. This led to the conduct of a much
broader project involving 13 companies.

A. Carcinogenicity Studies

In 2011, PhRMA published a database analysis (Ref. 4) confirming
the conclusion of an earlier paper. Based on a dataset of 182
compounds, it could be concluded that negative histopathology in a
chronic rat study together with a negative result in genotoxicity and
negative evidence of a hormonal mechanism would be useful in predicting
a negative outcome of the carcinogenicity study for these compounds.
This conclusion could apply to around 30 percent to 40 percent of the
compounds.
In the discussion of these results with the DRAs, a question was
raised regarding the impact of the pharmacological properties of the
compounds--first, for the false negative compounds, but with
consequences for all compounds. The European Union (EU) delegation has
conducted an analysis and concluded that a majority of the tumor-
inducing compounds were found to induce these tumors in relation to
their pharmacodynamic action. In addition, some compounds associated
with hepatocellular hypertrophy or liver enzyme induction were prone to
induce tumors not only in liver, but also in thyroid and testes.
In addition to the PhRMA dataset, FDA conducted a similar study
with 50 unique compounds, and the Japanese Pharmaceutical
Manufacturers' Association (JPMA) conducted a study with 64 unique
compounds from the PhRMA compound set. These datasets confirmed the
earlier analysis of the PhRMA dataset with respect to negative
predictivity, as well as the EU analysis regarding the relation with
the pharmacology. From discussions held in formulating ICH S1B
guidance, both the European Union (Ref. 5) and the United States (Ref.
6) published a dataset of several hundreds of compounds with lifetime
carcinogenicity studies in rats and mice. The EU delegation has used
the background data of the European Union, as well as the published
data from FDA relating the pharmacology of the compounds and the
outcome of the rat carcinogenicity studies. This analysis fully
confirmed the conclusions reached earlier on the PhRMA database.

B. Conclusions From Analyses Conducted

From the analysis of the various datasets (PhRMA, FDA, JPMA, and EU
+ FDA), it can be concluded that based on pharmacology, genotoxicity,
and chronic toxicity data (usually present at the end of phase 2 in the
development of a new pharmaceutical), the outcome of the 2-year rat
carcinogenicity study can be predicted with reasonable assurance at the
two extremes of the spectrum. Negative predictions can be made when
predictive carcinogenic signals are absent and positive predictions can
be made when such signals are present. An in-between category of
compounds still remains for which the outcome of the carcinogenicity
studies cannot be predicted with sufficient certainty.

III. Proposal

The processes initiated by this prospective proposal are expected
to improve pharmaceutical carcinogenicity evaluations, reduce use of
animals in accordance with the 3Rs (reduce/refine/replace) principle,
reduce the use of other drug development resources, and reduce
timelines to market authorization in some cases, all without compromise
to patient safety. Analyses of the datasets described in section II
suggest that a carcinogenicity assessment could be completed for
certain pharmaceuticals without conducting a 2-year rat carcinogenicity
study. From these databases, it can be shown that pharmacologic and
toxicologic data from numerous sources, including toxicology studies of
6-month duration or shorter, can be integrated to predict with
sufficient certainty that a given pharmaceutical will fall into one of
three main categories:
Category 1--so likely to be tumorigenic in humans that a
product would be labeled as such, and a 2-year rat study would not add
value;
Category 2--the available sets of pharmacologic and
toxicologic data indicate that tumorigenic potential for humans is
uncertain, and a 2-year rat study is likely to add value to human risk
assessment; and
Category 3a--so likely to be tumorigenic in rats but not
in humans through prior-established and well-recognized mechanisms
known to be human irrelevant that a 2-year rat study would not add
value; or
Category 3b--so likely not to be tumorigenic in either
rats or humans that no 2-year rat study is needed.
A set of proposed WOE (see Appendix 1 of this document) factors has
been developed. During the prospective evaluation period sponsors would
be encouraged to apply the available WOE for each pharmaceutical prior
to 2-year rat study completion and to assign a pharmaceutical candidate
to category 1, 2, 3a, or 3b in a CAD with respect to the expected value
and need for 2-year rat carcinogenicity testing. Sponsors would submit
the CAD to the DRAs explaining and justifying their position that a
waiver decision is, or is not, appropriate for each pharmaceutical
before knowing the outcome of carcinogenicity testing.

IV. Scope and Process for a Prospective Evaluation Period

A. Objective

The intent of the prospective evaluation period is to gain
experience and generate data that would address critical aspects of
proposed changes to the ICH S1 guidance that could not be answered by
retrospective analysis of the existing datasets. Specifically, these
critical aspects include how well the WOE will predict the outcome and
value of 2-year rat carcinogenicity study results, and how often the
DRAs are in accordance with sponsors and with each other regarding the
need to conduct a 2-year rat study based on the arguments put forth in
CADs.
Sponsors would be requested to submit CADs for all investigational
small molecule pharmaceuticals subject to a 2-year rat carcinogenicity
study under current ICH S1A guidance, as well as for those with ongoing
rat carcinogenicity studies, provided that dosing has not exceeded an
18-month duration. The date that the document was authored would be
specified in the CAD in relation to the start of the study and would
state that the assessment was not influenced by any signal from the
ongoing study. The results of the prospective evaluation period would
inform future revisions to the ICH S1 guidances. CADs submitted under
the prospective evaluation period would not be considered regulatory
documents or a substitute for the standard carcinogenicity assessment.
This request would not be applicable to investigational biologic
pharmaceuticals that follow the ICH S6 and S6 Addendum guidance
documents.\2\
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\2\ See the ICH guidance documents, ``S6 Preclinical Safety
Evaluation of Biotechnology-Derived Pharmaceuticals'' and ``S6
Addendum to Preclinical Safety Evaluation on Biotechnology-Derived
Pharmaceuticals,'' available at http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm or
http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/default.htm.

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[[Page 16683]]

B. Content of Submitted CADs

Submissions would assess the carcinogenic potential for the
investigational pharmaceutical under study, guided by the WOE approach
described in Appendix 1 of this document. The CAD would address each
factor considered pertinent to carcinogenic potential and would not
provide a general summary of the nonclinical profile of the
pharmaceutical. Not all factors in Appendix 1 would be expected to be
applicable or available in all cases.
In addition to addressing the WOE in Appendix 1, the CAD would
include the following critical elements:
1. Prediction of the actual tumor outcome from the planned or
ongoing 2-year rat study (positive/tumor target organs or absence of
tumors);
2. Projected value of the anticipated 2-year rat outcome to the
overall carcinogenicity assessment and human risk implications; and
3. Categorical assignment with explicit statement and explanation
as to whether the CAD supports: (1) Conduct of the 2-year rat study, or
(2) a waiver request from conducting the 2-year study.

C. Evaluation of CADs

The intent of the prospective evaluation period is to generate data
relevant to future changes to the ICH S1 guidance. As such, submitted
CADs would have no impact on the drug development program in any
region. Actual waivers of the 2-year rat study would not be granted,
nor would CADs be used to support regulatory actions on development
programs.
Each DRA would independently review submitted CADs at the time of
receipt for the adequacy of the prediction and would only provide
feedback to sponsors when the assessments inadequately address the
three critical elements cited in section IV.B of this document. DRAs
would convene to assess the concordance in predictions between DRAs and
sponsors and among DRAs.
The CADs would again be evaluated, based on the following three
points, after the DRAs have received results of the corresponding 2-
year rat study:
1. Accuracy of the prediction compared to the 2-year rat tumor
outcome using the WOE described in Appendix 1 of this document;
2. Accuracy of the sponsor's and the DRAs' original categorical
assignments relative to actual overall study outcome; and
3. Regulatory impact when the predicted tumor outcome may differ
from the actual tumor outcome.
The DRAs would maintain product confidentiality in conducting
independent analyses of the attributes data, as well as of the type of
compounds. Summary of anonymized results and the extent of sponsor
participation would be periodically reviewed by the ICH S1 EWG.
Concordance in interpretations between DRAs and sponsors and among the
DRAs would be analyzed at study termination. Final results of the
prospective evaluation period would be reviewed by the S1 EWG to inform
revision of the current ICH S1 guidance. Publication in a peer-reviewed
toxicological journal is planned.
The prospective evaluation period would end after approximately 50
CADs have been received by the DRAs. The goal of 50 CADs could change,
depending on the diversity of compounds addressed and the number of
pharmaceutical companies that would participate. For example, a narrow
focus on few drug classes and/or participation by few pharmaceutical
companies could introduce bias into the study and necessitate an
increase in the number of CADs. Based on analysis of the number of rat
study protocols and final rat study reports received by FDA since 2010,
it is estimated that a 2-year data collection period would be needed to
reach the goal of 50 CADs. Success of this effort hinges on the active
participation by pharmaceutical companies in submitting CADs to DRAs
for review.

D. Process of Submitting CADs

Sponsors would be requested to submit CADs to FDA; the EU European
Medicines Agency; and the Japanese Ministry of Health, Labour and
Welfare. We would request that CADs be sent to all three DRAs, whether
or not development programs are established in each region. CADs would
be requested for all investigational small molecule pharmaceuticals
subject to 2-year rat carcinogenicity study under the current ICH S1
guidance, as well as for those with ongoing rat carcinogenicity
studies, provided that dosing has not exceeded the 18-month duration.
We would encourage that the final results of the 2-year rat study be
submitted when available, irrespective of the timing of the marketing
application.

V. Comments

Interested persons may submit comments regarding the proposed
change in approach to carcinogenicity assessment, on the prospective
evaluation period intended to test this new approach, and on the WOE
factors proposed for inclusion in carcinogenicity assessment documents.
Submit either electronic comments regarding this document to http://www.regulations.gov or written comments to the Division of Dockets
Management (see ADDRESSES). It is only necessary to send one set of
comments. Identify comments with the docket number found in brackets in
the heading of this document. Received comments may be seen in the
Division of Dockets Management (see ADDRESSES) between 9 a.m. and 4
p.m., Monday through Friday, and will be posted to the docket at http://www.regulations.gov.

VI. References

The following references have been placed on display in the
Division of Dockets Management (see ADDRESSES) and may be seen by
interested persons between 9 a.m. and 4 p.m., Monday through Friday,
and are available electronically at http://www.regulations.gov.

1. Cohen, S.M., D. Robinson, and J. MacDonald, ``Alternative Models
for Carcinogenicity Testing'', Toxicological Sciences, vol. 64, pp.
14-19, 2001.
2. Cohen, S.M., ``Human Carcinogenic Risk Evaluation: An Alternative
Approach to the Two-Year Rodent Bioassay'', Toxicological Sciences,
vol. 80, pp. 225-229, 2004.
3. Reddy, M.V., F.D. Sistare, J.S. Christensen, et al., ``An
Evaluation of Chronic 6- and 12-Month Rat Toxicology Studies as
Predictors of 2-Year Tumor Outcome'', Veterinary Pathology, vol. 47,
pp. 614-629, 2010.
4. Sistare, F.D., D. Morton, C. Alden, et al., ``An Analysis of
Pharmaceutical Experience With Decades of Rat Carcinogenicity
Testing: Support for a Proposal to Modify Current Regulatory
Guidelines'', Toxicologic Pathology, vol. 39, pp. 716-744, 2011.
5. Van Oosterhout, J.P.J., J.W. Van der Laan, E.J. De Waal, et al.,
``The Utility of Two Rodent Species in Carcinogenic Risk Assessment
of Pharmaceuticals in Europe'', Regulatory Toxicology and
Pharmacology, vol. 25, pp. 6-17, 1997.
6. Contrera, J.F., A.C. Jacobs, and J.J. DeGeorge, ``Carcinogenicity
Testing and the Evaluation of Regulatory Requirements for
Pharmaceuticals'', Regulatory Toxicology and Pharmacology, vol. 25,
pp. 130-145, 1997.

Appendix 1. Weight-of-Evidence Factors for Consideration in a
Carcinogenicity Assessment Document

Each of the following factors should be considered in formulating a
prediction in the outcome and value of conducting a 2-year rat
carcinogenicity study and an overall integrated assessment of the
carcinogenic risk for humans. Some factors can be appropriate for both,
others more

[[Page 16684]]

appropriate for one or the other purpose.
Knowledge of Intended Drug Target and Pathway
Pharmacology, Secondary and Off-Target Pharmacology, and Drug Target
Distribution in Rats and Humans
Target and pathway related mechanistic/pharmacologic and understood
secondary pharmacologic characteristics can contribute to the
prediction of outcomes of carcinogenicity studies and can improve
prediction of potential human carcinogens. The CAD is expected to
convey a thorough and critical assessment of the sponsor's knowledge of
all such characteristics, including a comprehensive literature review
specifically addressing carcinogenicity risk. Examples of such data
sources include the following:
[cir] Prior experience with other molecules in the drug class
[cir] Experience with human genetic polymorphisms in the target or
pathway
[cir] Clinical trial data
[cir] Genetically engineered rodent models
[cir] Unintended pharmacology
[cir] Hormonal perturbation
[cir] Targeted tissue genomic biomarker measurements
Genetic Toxicology Study Results
The criteria in ICH S2(R1) \3\ will be used to evaluate genetic
toxicology data using a weight-of-evidence approach.
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\3\ See the ICH guidance ``S2(R1) Genotoxicity Testing and Data
Interpretation for Pharmaceuticals Intended for Human Use,''
available at http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm or
http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/default.htm.
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Histopathologic Evaluation of Repeated-Dose Rat Toxicology
Studies
Histopathologic risk factors of neoplasia should be evaluated in
the 6-month chronic rat study. Findings seen only in shorter-term
repeated dose rat toxicity studies are generally considered of less
value for 2-year rat study outcome prediction, but should be addressed.
Histopathologic findings of particular interest include cellular
hypertrophy, diffuse and/or focal cellular hyperplasia, persistent
tissue injury and/or chronic inflammation, preneoplastic changes, and
tumors. It is important to note that liver tumors are observed at
relatively high frequency in the rat, sometimes with Leydig cell and
thyroid follicular cell tumors. Hepatocellular hypertrophy associated
with increased liver weight often results from hepatic enzyme
induction, the latter being a well-understood mechanism of rodent
specific tumorigenesis at these sites with little relevance to humans
(Refs. 1 and 2).
Exposure Margins in Chronic Rat Toxicology Studies
A high exposure margin in a chronic rat toxicology study absent of
any carcinogenic risk factors can provide additional support for a
carcinogenicity study waiver. The inability to achieve high exposure
margins in a chronic rat toxicology study because of limitations of
tolerability, pharmacology, or absorption would not preclude a
carcinogenicity study waiver.
Evidence of Hormonal Perturbation
Evidence of hormonal perturbation should be considered from both
repeated-dose and reproductive toxicology studies. Such evidence can
come from weight, gross and/or microscopic changes in endocrine organs,
or parameters from reproductive toxicology studies. Serum hormone
levels can be useful to address findings but are not always essential.
Immune Suppression
Immunosuppression can be a causative factor for tumorigenesis in
humans. As such, immunotoxicological parameters should be examined
according to the ICH S8 guidance.\4\
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\4\ See the ICH guidance ``S8 Immunotoxicity Studies for Human
Pharmaceuticals,'' available at http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm or
http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/default.htm.
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Special Studies and Endpoints
Data from special stains, new biomarkers, emerging technologies,
and alternative test systems can be submitted with scientific rationale
to help explain or predict animal and/or human carcinogenic pathways
and mechanisms when they would contribute meaningfully.
Results of Non-Rodent Chronic Study
Assessment of carcinogenic risk factors in the non-rodent
toxicology studies should be considered for human risk assessment
regardless of results in the chronic rat study.
Transgenic Mouse Study
A transgenic mouse carcinogenicity study (usually rasH2 or p53+/-
mouse) is not required for the WOE argument. However, if conducted on a
case-by-case basis, a transgenic mouse carcinogenicity study can
contribute to the WOE.

References

1. Cook, J.C., G.R. Klinefelter, J.F. Hardisty, et al., ``Rodent
Leydig Cell Tumorigenesis: A Review of the Physiology, Pathology,
Mechanisms and Relevance to Humans'', Critical Reviews in
Toxicology, vol. 29, pp. 169-261, 1999.
2. McClain, R.M., ``The Significance of Hepatic Microsomal Enzyme
Induction and Altered Thyroid Function in Rats: Implications for
Thyroid Gland Neoplasia'', Toxicologic Pathology, vol. 17, pp. 294-
306, 1989.

Dated: March 12, 2013.
Leslie Kux,
Assistant Commissioner for Policy.
[FR Doc. 2013-06145 Filed 3-15-13; 8:45 am]
BILLING CODE 4160-01-P