The Role of Public Standards in the Development of Biosimilars

Anthony Mire-Sluis, Vice President,

North America, Singapore, Abingdon, Contract and Product Quality

Amgen Inc.

There are Several Variations of Public Standards for Biotechnology Products Currently Available or Under Development

• Pharmacopoeia Product Monographs and Reference Standards

• Pharmacopoeia Method Performance Monographs

• Pharmacopoeia General Chapters

• WHO International Potency Standards

• NIBSC Reference Reagents

• NIST Standards

There are many Potential roles for Public Standards for Biologics

Are public standards relevant for…

• Approval standards

• Definition of an active substance

• Standardizing “potency” or “functionality”

• In the context of a modern QbD control strategy

• Constraining “drift” between similar products

• Facilitating a common framework for qualification of analytical methods and standards

4

Biotechnology Products Are Naturally Complex

• Biotechnology products never consist of a single moiety:

• Product related substances • Protein variants that have similar biological activity to the ‘parent’

molecule

• Product related impurities • Protein variants that do not have similar biological activity to the

‘parent’ molecule

• Process related impurities • Host Cell Proteins

• Endotoxins

• Host cell DNA

• Media components

• Residual processing agents (e.g. protein A, process chemicals)

• Process Contaminants • Adventitious agents

• Leachables

5

Even in a Single Protein Product There can be Multiple Product Variants

• 2 x 6 x 4 x 4 x 5 x 5 x 2 = 9600

K

pyro-E O

D

G

G

D

O

D

• (9600)2≈ 108

O

O

• Methionine oxidation (2 x 2)

pyro-E • Pyro-Glu (2)

• High mannose, G0, G1, G1, G2 (5)

• Sialylation (5)

D

D

D • Deamidation (3 x 2)

G

G

• Glycation (2 x 2)

K

• C-term Lys (2)

Kozlowski and Swann

6

Pharmacopoeia Monographs and

Reference Standards for Biotechnology

Products

Provisions of the FD&C Act apply to biologics regulated

under PHS Act

• PHS ACT (42 USC 262)- 262(j) Application of FDCA:

• The Federal Food, Drug, and Cosmetic Act… …applies to a

biological product subject to regulation under this section, except

that a product for which a license has been approved under

subsection (a) shall not be required to have an approved application

under section 505 of such Act (21 U.S.C. 355)

• Biological products approved under the PHS Act are subject to the

adulteration and misbranding provisions of FD&C Act

• Section 501(b) - Adulterated Drugs and Devices

– A drug or device shall be deemed to be adulterated if it purports to be or is represented as a drug the name of which is recognized in an official compendium, and its strength differs from, or its quality or purity falls below, the standards set forth in such compendium.

– Such determination as to strength, quality, or purity shall be made in accordance with the tests or methods of assay set forth in such compendium…

• If an official monograph in USP-NF is available, a US

biological product must conform

Pharmacopoeia Monographs Play a Role in Assuring the Quality of Biological Products

• Modern public standards should exist for all medicines, as

they can play a key role in ensuring quality, safety and

benefit by allowing independent testing

• USP standards, both monographs and associated reference standards, can be used to control product variants during the lifecycle of a biological product

• USP Reference Standards may have multiple compendial

uses, and are made available to the public without

restriction

• Chapters support biological product development by

providing validated procedures (numbered below 1000) that

only require verification, as well as general quality guidance

(numbered above 1000)

9

There Are Special Considerations For The Development of Monographs for Biotechnology Products - Setting Limits

• For small molecules, the API is usually homogenous of high purity, very reproducible lot to lot, tests are generally highly precise and are able to detect most low level impurities

• For proteins, manufacturing processes produce heterogeneous material with a certain amount of variability lot to lot, tests are generally more variable (e.g. gel based methods) and often not as sensitive

• Does one use the innovator’s specifications as limits? • Specifications alone do not assure product safety/efficacy

• May include terms such as ‘no new peaks within assay variability’ which requires a reference standard and understanding of assay precision

• Specification limits can be altered over time during a product lifecycle – thus should a monograph require updating as innovator specifications change?

10

There Are Special Considerations For The Development of Monographs for Biotechnology Products - Analytical Techniques

• By the time a product is licensed, a company will have developed highly product specific assays that take extensive time, money and often novelty – this can lead to Intellectual Property issues with biosimilars

• As the lifecycle of a product proceeds, tests may be dropped as the innovator proves process consistency or through validation

• New technologies to characterize biologicals are being developed all the time, so pharmacopeias should assure continuous improvement in biological monographs

• Some assays (e.g. bioassays or immunoassays) may utilize product specific reagents – how to deal with that?

11

Process Related Impurities are a Special Concern for Protein Products – HCPs

• Protein products contain host related proteins that are very specific to the cell line and process clearance mechanisms

• It is not just the amount that is important, but the actual types of HCPs in the product – since they could be immunogenic in extremely small amounts

• Only manufacture/product specific preclinical and clinical studies can assure safety

• Therefore, simply requiring the level of HCPs to be met in a monograph is not appropriate

• The limit is often defined as ‘as approved by the competent authority’ but not sure how one controls for the types of HCPs (not often revealed in specification testing)

12

Glycosylation Requirements are Difficult to set Appropriately

• Glycosylation patterns are heterogeneous and can vary from batch to batch.

• The acceptable variability for an originator product is defined by preclinical and clinical studies whereby the role of glycosylation in PK, bioavailability, clearance and potency are established

• Complex structure of large molecules can make it very difficult to define the acceptable attribute ranges for a class of products - sometimes the structure-function relationship may not be easily defined and noticed by the clinical result

• The analytical tests to define glycosylation profiles go way beyond simple isoform patterns and would be difficult to include in a monograph – similar IEF patterns does not assure comparability

• How different can a glycoform pattern be before it is no longer similar?

13

There Are Special Considerations For The Development of Monographs for Biotechnology Products - Potency Assays

• Bioassays often require company specific developed cell lines

• This has necessitated the use of publicly available cell lines and correlations of innovator to pharmacopoeia assays

• This was the case for the USP Filgrastim monograph where a suitable potency assay was developed

• Some potency assays are binding assays that use company specific reagents

• What to do if an International Standard is not available?

• Use of mass units is not meaningful without a reference standard being made available

14

The Concern over Approval Standards for Biotechnology Products

• There is concern that monographs could be linked to regulatory approvals in lieu of comparability data or a fully justified control strategy.

• Unlike small molecule products, the analytical testing prescribed in any monograph/s for biotechnology products is highly unlikely to assure clinical comparability for the many reasons discussed

• Some developing regulatory authorities regard compendial tests and limits as ‘the’ quality requirements to license a product

Quote from Public Comment of USP to Colombia Health Authority

“We would note that the limited purpose of the Identity and other tests in USP monographs is to determine whether a particular monograph applies and the key quality attributes of a drug are achieved. Such compendial standards are not sufficient to establish biological identity or activity, safety and effectiveness, or other attributes that are required for licensure. Thus as noted in the attached recent submission by USP to the U.S. regulatory authority, the U.S. Food and Drug Administration, regarding an FDA draft biosimilar guidance, “Where two biologics share a compendial identity, this does not mean they are one and the same drug; only that they are subject to one and the same USP standard for quality.”

16

Could Monographs Help Control “Divergence" Post-approval?

• FDA has the authority to approve biosimilars as “interchangeable biologics” which means they may be substituted without the intervention of a prescriber

• One challenge is that serial post-approval changes could result in “divergence” between products, potentially impacting interchangeability

• Given the issues previously discussed monographs may be of limited utility to control for divergence of all relevant attributes

• Standards for potency or other functions (e.g., effector functions) may be useful to constrain divergence provided:

• Assays are fit for purpose and suitably precise

• Functions measured in vitro correlate to clinical potency

17

The Use of Pharmacopoeia Method

Performance Standards

Monoclonal Antibodies and Platform Assays

• Quality Control Assays for Monoclonal Antibodies

Product Class Analytical Methods - platform assays

• Examples

• Size exclusion chromatography

• Isoelectric Focusing

• Oligosaccharide assay

• Peptide Mapping

• Process Related Impurity assays

o Host cell protein

o DNA

o Protein A

• Compendial Assays; Endotoxin, pH, Conductivity, Sterility

<129> Analytical Procedures for Recombinant Therapeutic Monoclonal Antibodies - Chapter Scope

• Defines accepted procedures for the quality control of antibodies.

• Focuses on chimeric, human or humanized IgG isotype monoclonal antibodies (mAbs) and subtypes

• Applies to mAbs for therapeutic and prophylactic use and for use in vivo as diagnostics.

• Does not apply to mAbs used as reagents in the manufacture of medicinal products.

• Does not apply to mAbs produced in ascites, for which requirements are decided by the competent authority.

• Will take a flexible approach to defining the quality attributes and tests required to assure a minimum level of quality

Quality Control Assays for mAbs

• Included in <129> chapter • Size exclusion chromatography

• Purity: CE-SDS

• Oligosaccharide assays

• Included in other USP chapters • Content :<57> Total Protein Measurement

• <1055> Biotechnology-Derived Articles—Peptide Mapping

• Process Related Impurity assays

• <1132> Residual Host Cell Protein Measurement in Biopharmaceuticals

• <30> Residual DNA Testing

• Protein A

• <791> pH

• <631> Color and Achromicity

• <71> Sterility Tests

Summary

• USP <129> chapter contains validated compendial

procedures with established system suitability criteria &

associated reference standard

• USP mAb round robin study clearly demonstrated that

procedures & RS proposed in <129> are appropriate

across antibody preparations

• System suitability criteria will be carefully re-evaluated

based on the mAb round robin study results.

• USP mAb Expert Panel recommends to the USP

General Chapters Biological Analysis Expert Committee

that <129> chapter be moved to official in USP37-NF32,

Second Supplement

22

The Importance of WHO and NIBSC

Potency Standards and reference

Reagents

How To Determine Potency

• It is still amazing how long this question has been asked

• The WHO set up a biological assay standardization program over 100 years ago – why is it still an issue?

• Although the statisticians are still refining analysis methodology, relative potency is the most utilized and valid process

23

Examples of Assay Dose Response Curves

Assay Type A Assay Type B Assay Type C

Day1

Day2

1 unit 1 unit

Pro

du

ct

ind

uce

d r

es

po

nse

[Product] 1 unit

Pro

du

ct

ind

uce

d r

es

po

nse

[Product] 1 unit P

rod

uc

t in

du

ce

d r

es

po

nse

[Product]

24

An Example of Assay Titration/dilution Curves

Standard

Sample

25

Biological Estimates of the Mass Content of a Preparation of a Cytokine by Laboratories Using in-house standards/units

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0

20

40

60

80

100

120

140

160

180

200

220

240

Laboratory Code Number

Esti

mate

d C

on

ten

t o

f IL

-4 (

ng

/am

po

ule

)

26

Estimates of Biological Potency of a Cytokine using the WHO International Standard

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

2000

4000

6000

8000

10000

12000

Laboratory Code Number

Po

ten

cy E

sti

mate

(IU

/am

po

ule

)

27

28

NIST Standards

National Institute of Standards and Technology

• Founded in 1901 as National

Bureau of Standards

• Non-regulatory agency within

U.S. Department of Commerce

• NIST responsible for US

physical standards, test

methods, & calibrations

Unique Mission within the Federal Government to promote U.S. innovation

and industrial competitiveness by advancing measurement science,

standards, and technology in ways that enhance economic security and

improve our quality of life

NIST mAb Reference Material + Data

NIST mAb Attributes:

• Humanized mAb (IgG1κ) expressed in murine

suspension culture

• Frozen bulk “Drug-like substance”

• 100 and 10 mg/mL, ≥ 98% purity

• 12.5 mM L-His, 12.5 mM L-His HCl (pH 6.0)

Approach for IgG Reference Material:

• Complete rigorous interlaboratory characterization

• Results used for book compilation

• Compile reference data, methods, etc.

• End user accessibility to http://igg.nist.gov/

• Certify for concentration traceable to the kg

• SRM made available to biopharmaceutical community

Companion Reference Data

Amino Acid Sequencing

Amino Acid Analysis

N-terminal Sequencing

C-terminal Sequencing

Peptide Mapping by MS

S-S Bridge Analysis

Glycosylation Analysis

Molecular Weight Information

Isoelectric Focusing

SDS-PAGE

Extinction Coefficient

Post-Translational Modifications

Spectroscopic Profiles: CD,

NMR

LC: SEC, RP, IEX

Protein Structure: NIST Reference Mass Spectral (MS) Library of Antibody Therapeutics

Antibody Library with

NIST reference material

glycans glycopeptides

peptides

intact &

large fragments?

• Real spectra of species

• High quality data:

“consensus spectra”

• Confident identification

• Faster data analysis

NIST Standards for Protein Particles

Differences in physical properties between polystyrene (PSL) calibration beads and actual protein particles lead to large disagreements in counts.

Solutions:

• Instrument models

• Reference materials for particle size distribution

= • Refractive index is the primary

cause of discrepancies of optical

counting methods

• Morphology is a secondary cause

Protein Particle Standards: Activities & Status

1. NIST: Ethylene tetrafluoroethylene mimic of protein aggregates, polydisperse suspension, 0.5 to 25 µm

24 lab intercomparison; paper in review

Reference material being packaged & characterized

Contact: Dean.Ripple@nist.gov

2. MicroMeasurement Laboratories

Commercializing NIST ETFE standard

Coordinating efforts with interested customers

Exploring with NIST use of fluoropolymer for visible standard

Contact: Dan Berdovich, DBerdovich@mmlabs.com

3. Liquidia Technologies: Proprietary, low-optical contrast polymer, monodisperse & non-spherical particles, 0.2 to 1 µm

Contact: Derek.Schorzman@liquidia.com

4. AIST (Japan): Recombinant proteins, 6 kDa to 480kDa

Initial protein batches produced

Contact: Hideki Watanabi, hideki.watanabe@aist.go.jp

34

Conclusions

• Developing appropriate, meaningful monographs for protein products requires considerations beyond those used for small molecule products

• Unlike small molecule generics, it is generally accepted that a set of analytical tests alone does not assure product safety or efficacy of biosimilars and some level of preclinical/clinical testing is required

• Therefore, ensuring that monographs for biotechnology products are seen as the ‘necessary but not sufficient’ and that meeting those requirements does not assure interchangeability is essential

• Performance standards are a valuable contribution to ensure that methods used to characterize or release biotechnology products are appropriate – and can be used comparatively

• The use of reference materials from various public sources can also be an aid to the characterization, measurement and development of biosimilar products

Acknowledgements

• USP Team

• Tina Morris, Anita Szajek, Fouad Atouf, Mary Crivellone and many others

• NIST Team

• Mike Tarlov, John Schiel, Dean Ripple and many others

• WHO Team

• Robin Thorpe, Meenu Wadhwa, Chris Bird and many others

• Amgen Team

• Gino Grampp, Virginia Acha and many others