# Presentation: 036314

## Characterization of Protein Pharmaceutical Products

- Charles E. DiLiberti
- Vice President, Scientific Affairs
- Barr Laboratories, Inc.

- FDA Workshop on Proteins - 9/14/04

## Old Paradigm

- Characterization of many proteins was incomplete
- Analytical methods crude, biologically-based
- Upper limit for precise chemical characterization was a few thousand Daltons
- Analytical variability  intra-process variability
*In vivo* studies needed to ensure comparable safety and efficacy
- “Product is the process” myth

- FDA Workshop on Proteins - 9/14/04

## New Paradigm

- Powerful analytical methodology, especially high resolution tandem mass spectrometry
- Complete covalent structure routine for proteins over 100,000 Daltons
- 1 Dalton change in proteins routinely detectable
- Sensitive methods to detect differences in higher order structure
- Chemistry-based methods
- Analytical variability  intra-process variability
- Many *in vivo* studies may not be necessary

- FDA Workshop on Proteins - 9/14/04

## The Product is Not the Process

- Old “product is the process” mantra implies the process could impact safety/efficacy without being detectable analytically
- If true, then could never justify use of comparability protocols for process/site/formulation changes
- _Reality_: current analytical tools are capable of discerning not only clinically significant product changes, but even minute batch-to-batch differences

- FDA Workshop on Proteins - 9/14/04

## Measures of Product Equivalence

- Analytical uncertainty

- Clinical Equivalence Range

- Intra-process variability

- Clinically distinguishable product

- Clinically distinguishable product

**Analytical characterization:**

**Same process:**

**Comparative Clinical Studies:**

- FDA Workshop on Proteins - 9/14/04

## Measures of Product Equivalence

- Analytical characterization provides the most sensitive and selective measure of protein product equivalence
- Clinical studies are the least sensitive and least reliable measure of protein product equivalence

- FDA Workshop on Proteins - 9/14/04

## Comparative Characterization

- Scientifically sound, practical pathway for _comparative_ characterization of two protein pharmaceutical products to demonstrate  _pharmaceutical_ _equivalence_
- Same characterization principles should apply equally to justify process changes as well as demonstrate pharmaceutical equivalence of generic and pioneer protein products
- Failure of pioneer manufacturer to characterize product fully should not impede approval of generic protein products

- FDA Workshop on Proteins - 9/14/04

## Continuum of Products

- Like conventional pharmaceuticals, protein therapeutic products range from simple to complex
- No magic about biological source – decades of experience in fermented antibiotics and other naturally-derived conventional pharmaceuticals
- No magic about peptide bonds – well understood
- Characterization of proteins and conventional pharmaceuticals similar except:
- Some proteins are large enough to have potential to misfold and aggregate – important to analyze secondary and higher order structure
- Size and chemistry of protein molecules requires use of different types of analytical methods

- FDA Workshop on Proteins - 9/14/04

## Protein Characterization - Overview

- Current technology enables comprehensive comparative characterization of all protein therapeutic products
- Pharmaceutical equivalence may be concluded on comparative characterization – process irrelevevant
- Characterization justifies abbreviated approval process for later products with same active chemical entity
- Extent of clinical program inversely related to extent of characterization
- Many protein products can be characterized so thoroughly as to eliminate need for clinical studies

- FDA Workshop on Proteins - 9/14/04

## Protein Characterization – Strategy

- Characteristics of particular protein dictate characterization strategy – one size does not fit all
- Apply comprehensive array of sensitive and selective analytical methods to multiple batches
- Orthogonal methods – virtually every observable property of a protein is probed:
- covalent structure, conformation, pI, aggregation, charge, mass, fragmentation, surface structure, hydrophobicity, spectrophotometric, magnetic resonance, fluorescence, light scattering, sedimentation, electrophoretic properties, charge, immunological properties, enzyme activity, biological potency, substituent patterns, etc.

- FDA Workshop on Proteins - 9/14/04

## Protein Characterization – Strategy

- Analytical results _collectively_ provide highly sensitive and selective _fingerprint_ of product
- Show that scope of variation seen with test product/process is comparable to reference product/process
- Process is not germane to comparison - two different processes can yield therapeutically equivalent products

- FDA Workshop on Proteins - 9/14/04

## What is the capability of current analytical technology to adequately characterize protein products?

- Excellent:
- Complete elucidation of covalent structure
- Peptide mapping with high resolution LC/MS (Q-TOF) routinely locates every atom in peptide backbone
- Sensitive methods for _comparing_ higher order structure (fingerprint)
- CD, HPLC, FTIR, fluorescence, NMR, SEC, light scattering, AUC, ELISA, SPR

- FDA Workshop on Proteins - 9/14/04

## What is the capability of current analytical technology to adequately characterize protein products? – cont’d

- Sensitive methods for measuring impurities
- HPLC, SEC, IEC, SDS-PAGE, IEF
- Comparison of products using multiple orthogonal analytical methods provides high level of assurance of pharmaceutical equivalence

- FDA Workshop on Proteins - 9/14/04

## Are there new technologies that hold promise for helping to characterize proteins?

- Yes - multidimensional analytical methods (e.g., LC/MS, 2D NMR) provide greater information content than 1D methods
- Multivariate mathematical methods for analyzing complex mixture data can reveal  individual components that would otherwise be obscured

- FDA Workshop on Proteins - 9/14/04

## Is it possible to accurately predict safety and efficacy from analytical studies?

- _Better question_: Is it possible to ensure that two products have equivalent safety and efficacy from analytical studies?
- Yes - modern analytical methods are much more sensitive indicators of product changes than are clinical studies. Analytical methods can readily detect minute batch-to-batch variations that are far too small to have any clinical consequence

- FDA Workshop on Proteins - 9/14/04

## Conclusions

- Same characterization strategies should be applied to:
- Justify process changes
- Show pharmaceutical equivalence between generic and reference products
- Modern comparative analytical characterization supplants need for *in vivo* studies on later products with same chemical entity
- No scientific reason to delay approval of safe, effective generic protein therapeutic products – technology and strategies already in use

- FDA Workshop on Proteins - 9/14/04