# Presentation: 035238

## Pharmacology and Toxicology Information in Support of Protein Therapeutics

**Anne M. Pilaro, Ph.D.**
**FDA/CDER/ODE VI/DTBOP**
**NCI Small Business Initiative**
**Workshop on Clinical Development**
**June 24, 2004**

## Objectives for Today’s Presentation

**Summarize some differences between small molecules and protein therapeutics **
**Brief review of pharmacology and toxicology information in support of IND application for protein therapeutics**
**Introduce current guidance for toxicology testing of protein biotherapeutics**

## What Does ODE VI Regulate?

**Classes of Biological Products**
**Natural**
**leukocyte-derived (IFNs, interleukins)**
**enzymes, other cell-derived proteins**
**Biotechnology-derived**
**recombinant proteins (*****E. coli*****, CHO, yeast)**
**monoclonal antibodies (*****in vivo*****, *****in vitro*****)**
**recombinant proteins produced in transgenic animals**
**Synthetic**

## What Does ODE VI Regulate?

**Recombinant proteins**
**cytokines**
**enzymes**
**hematopoietic growth factors**
**neuroactive peptides**
**Thrombolytics and fibrinolytics**
**Monoclonal Abs (diagnostic, therapeutic, preventative)**
**Peptides greater than 20 amino acids**
**Other non-vaccine immunotherapies**

## Some Basic Differences Between Drugs and Biologics

_**Traditional Drugs**_
**Low molecular weight**
**Previous examples**
**Historical data base**
**Maximal tolerated dose**
**Species-independent**
**Specific mechanisms**
**Metabolized**
**Guidelines**

_**Biologic Therapies**_
**High molecular weight**
**Unique**
**Concurrent controls**
**Optimal biologic dose**
**Species-specific**
**Pleiotropic mechanisms**
**Degraded**
**Guidances**

## Traditional Drugs are small...

**FLUDARA****®**** (fludarabine phosphate)**
**Molecular weight 365.2 daltons**
**Chemical formula C****10****H****13****FN****5****O****7****P**

## Biological Drugs are BIG!

**RITUXAN****®**** (rituximab)**
**Molecular weight 145,000 daltons**
**Chemical formula (non-glycosylated IgG1********) ****C****3264****H****5002****N****840****O****998****S****20**

## Review of Preclinical Studies for Small Molecule Drugs vs. Biologics

**Small molecule drugs: **
**pharmacology establishes rationale, but “proof” is in clinical trial**
**toxicology testing by standard paradigms**
**two test animal species to maximize chances of detecting toxicities**
**duration of tox testing **_**>**_** support clinical use**
**genotoxicity testing required before first in man**
**ADME studies generally useful**
**demonstration of safety = ultimate goal**

## Review of Preclinical Studies for Small Molecule Drugs vs. Biologics

**Protein therapeutics: **
**pharmacology establishes rationale**
**allows selection of pharmacologic active dose**
**used to establish “therapeutic window”**
**toxicology testing has no standard paradigm**
**toxicities are often extensions of pharmacologic activity**
**follows the principles set forth by ICH S6 guidance**
**margins of safety are frequently < 10-fold**
**demonstration of safety = ****ultimate goal**

## The ICH S6 Document

**The ICH S6 Document**

**Title: Preclinical Testing of Biotechnology-Derived Pharmaceuticals**
**usage of relevant vs. nonrelevant species**
**usage of animal models of disease**
**immunogenicity testing and its implications**
**genotoxicity testing**
**chronic toxicity testing**
**carcinogenicity testing**
**preclinical study design**

## Toxicology Testing of Biotech-Derived Agents: ICH-S6

**Toxicology Testing of Biotech-Derived Agents: ICH-S6**

**General Principles**
**sufficiently well-characterized products**
**rely on purification processes to remove impurities/contaminants**
**comparability of test material demonstrated throughout development**
**conventional approaches to toxicity studies often NOT appropriate to address unique issues**
**GLP compliance**

## Characterization of General Toxicity

**Characterization of General Toxicity**

**Administration/Dose Selection***
**ROA, dosing regimen should mimic proposed clinical use**
**alternative routes/regimens acceptable in some cases**
**attainment of toxic dose & NOAEL desirable**
**multiples of human dose needed to determine adequate safety margins can vary with product class & clinical indication**
**	****	****	****	****	****	****	****	***** Sec 3.5**

## Animal Species/Model Selection*

**Animal Species/Model Selection***

**Standard toxicology paradigms often *****not***** adequate or appropriate**
**Use of *****relevant***** species**
**single relevant species with justification**
**limited toxicology in a single “nonrelevant” species**
**Alternative approaches**
**transgenic animals**
**homologous proteins**
**animal models of disease**		*** Sec 3.3**

## Single/Repeat Dose Toxicity Studies*

**Single/Repeat Dose Toxicity Studies***

**use *****relevant***** animal species**
**include TK, Ab measurement, recovery period**
**short-term clinical use/acute life-threatening disease = toxicology studies of up to 2 weeks duration**
**chronic use = toxicology studies up to 6 months duration****	****	****	****	**
**	****	****	****	****	****	****	****	***** Sec 4.4**

## Characterization of Specific Toxicities

**Genotoxicity**
**Chronic toxicity**
**Immunogenicity**
**Repro/Developmental Toxicity**
**Carcinogenicity**

## Characterization of Specific Toxicities

**Genotoxicity**
**for protein therapeutics:**
**standard mutagenicity assays not applicable**
**effects on proliferation, transformation in human cell lines ****may be**** more appropriate for *****in vitro***** testing**
**integration not usually an issue for proteins**
**scientific basis to justify method selection**
**most sensitive, appropriate technique available**
**use data to predict risk of mutagenesis *****in vivo***
**frequency/risk analysis**

## Characterization of Specific Toxicities

**Chronic Toxicity**
**designed to assess potential cumulative toxicity**
**support long-term administration in the clinic**
**most protein therapies are of limited duration**
**single, or small number of administrations over short time span**
**limited number for lifetime replacement therapies**

## Characterization of Specific Toxicities

**Chronic Toxicity, cont’d**
**need for chronic toxicology determined by “product-specific” issues, patient indication**
**assess potential delayed or extended toxicity**
**daily, repeat administrations probably not feasible**
**antibody development/host response (****immunogenicity****)**
**limits duration of pharm/tox effects**
**limits duration of administration**

## Characterization of Specific Toxicities

**Repro/Developmental Toxicity**
**need for studies determined individually**
**dependent on product class, patient population, duration of treatment**
**studies ****expected**** for product used in pregnant females, WCBP**
**species-specificity limits testing to Seg 2/3**
**“****stand-alone” fertility studies not useful with NHP**
**small litter size (n = 1) with NHP means large n, $$$**
**alternative approaches are encouraged, e.g. hormone surrogates**
**ODE VI works with sponsors to design studies to address specific safety questions as needed**

## Characterization of Specific Toxicities

**Carcinogenicity**
**standard rodent models not likely appropriate**
**species-specificity**
**lifetime administration of protein not feasible**
**immunogenicity limits duration of treatment**
**immune effects may also affect tumor response**
**“****product-specific” studies case-by-case**
**dependent on product class, duration of clinical dosing, patient population, risks of long-term exposure**
**may be obviated by long-term, clinical follow-up**
**ODE VI works with sponsors to design studies to address specific safety questions as needed**

## Review so far...

**Preclinical studies for therapeutic proteins have no “set” study paradigm**
**design and implementation must consider clinical indication, population, and product characteristics**
**Traditional animal toxicology models may not be appropriate or feasible**
**Often studies have to be “individualized” to address specific safety concerns **

## Safety Issues Will Vary With Each Product Class

**Monoclonal antibodies (naked or conjugated)**
**cross-reactivity with normal tissue**
**immunogenicity/antibody production**
**conjugate and/or linker toxicity**
**“****bystander” toxicity of radiolabeled species**

## Safety Issues Will Vary With Each Product Class

**Cytokines and/or growth factors**
**frequency/duration of therapy**
**species-specificity**
**interaction with host endogenous cascade**
**tumor-promoting potential**
**immunogenicity/antibody production**

## Summary

**Toxicology programs for therapeutic proteins require novel approaches to obtain data**
**no “one size fits all” paradigm for biologics **
**traditional animal toxicology models may not be appropriate or feasible**
**studies may have to be “individualized” to address specific safety concerns**

## Summary

**Toxicology studies for therapeutic proteins should be:**
**rational , scientifically designed, and problem solving**
**based on the best available technology, methods to date**
**follow guidance set forth by ICH S6**
**careful design, judicious use of animals**

## Summary

**Current approach is to design preclinical toxicology studies to consider:**
**basic biology of the product**
**clinical indication, *****e.g.***** life-threatening or not**
**patient population under study**

## Summary

**Animal studies to determine safety are selected based on:**
**body of information available**
**question being asked**
**Information may be obtained in alternative animal models**
**non-human primates are not *****a priori***** necessary**

## Summary

**but... animal studies really only give you a “best guess” of what to expect**
**no animal model, including humans is 100% predictive of response in man**
**sometimes animal studies can give a false sense of security**
**however, these models may be useful in evaluation of mechanism, other toxicities**

## Some Further Resources

**ICH Guidances**
**ICH S6: Safety Studies for Biotechnological Products**
**ICH M3: Timing of Pre-clinical Studies in Relation to Clinical Trials**
**ICH S5a: Detection of Toxicity to Reproduction for Medicinal Products**
**ICH S2b: Standard Battery of Genotoxicity Testing**
**Available at ****www.ich.org/ich5s.html**** **

## Some Further Resources

**Points to Consider**
**http://www.fda.gov/cber/guidelines**
**Points to Consider in the Manufacture and Testing of Monoclonal Antibody Products for Human Use - 2/28/97**
**Points to Consider in the Manufacture and Testing of Therapeutic Products for Human Use Derived from Transgenic Animals - 1995**

## Some Further Resources

**Guidance Documents**
**http://www.fda.gov/cber/gdlns.htm**
**Guidance for Industry: Clinical Development Programs for Drugs, Devices, and Biological Products for the Treatment of Rheumatoid Arthritis**

## Toxicology Staff in ODE VICAPT M. David Green Ph.D., Chief

_**DTBOP Staff**_
**Wen-Yi Gao, M.D., Ph.D.**
**Melanie Hartsough, Ph.D.**
**Anne M. Pilaro, Ph.D.**
**Andrea Weir, Ph.D.**
**Alexandra Worobec, M.D.**
**(301) 827-5097**

_**DTBIMP Staff**_
**Hanan Ghantous, Ph.D.**
**Anita O’Connor, Ph.D.**
**Barbara Wilcox, Ph.D.**
**(301) 827-5096**