Download History of Sequence Variants

History of Sequence Variants
History of Sequence Variants
WCBP
24January2012
A long, long time ago on a planet far away …
• 1980s – initial rDNA‐derived products approved with little concern about sequence
approved with little concern about sequence variants
• 1990 –
1990 An advisor for HA suggested that it was An ad isor for HA s ested that it as
appropriate to clone and sequence 30 rDNA plasmids to assure that the correct sequence
plasmids to assure that the correct sequence was employed in 95% of the microbial hosts based on statistical confidence considerations
based on statistical confidence considerations
• 1991 ‐ West Coast PDA held a meeting in San Francisco on “Genetic Stability”
Genetic Stability Meeting Outcomes
Genetic Stability Meeting Outcomes
• Rob Garnick reviewed the tPA experience showing that peptide mapping was very useful in
showing that peptide mapping was very useful in demonstrating that most of the rDNA protein made & purified had the same sequence
made & purified had the same sequence
• Len Hayflick reminded the audience that genetic stability does not exist & if genetic mutation was
stability does not exist, & if genetic mutation was not Mother Nature’s way, we would still be frogs
• Some Health Authorities and reviewers were Some Health Authorities and reviewers were
concerned that mutations might occur and lead to safety or immunogenicity issues and
to safety or immunogenicity issues, and somehow cloning and sequencing was a solution
Further events
Further events
•
•
•
1992 – HA Advisor further opined that cDNA cloning & sequencing 30 mRNAs from mammalian cells was a good approach too
mRNAs from mammalian cells was a good approach, too
1993 – ICH agreed to prepare guidance 1993 – IABS sponsored a meeting on Genetic Stability & Recombinant y(
p
83, 1994) which ,
)
Product Consistency (Develop. Biol. Standard. Vol
summarized the current scientific information & consensus
– Mutation & translational substitution is inevitable, and sometimes can be detected
– Life as we know it seems to be able to tolerate considerable levels of mutation Life as we know it seems to be able to tolerate considerable levels of mutation
in most circumstances
– Useful to show that gross levels of mutation are not present & that predominant sequences present are those intended for desired product
– Whether using nucleic acid or protein based methods to assure predominant Whether using nucleic acid or protein based methods to assure predominant
product sequence is correct, understand method sensitivity
•
1995 – ICH Q5B appears as a Step 4 document, and was rapidly accepted as appropriate guidance So, fast forwarding to the present …
So, fast forwarding to the present …
• We
We now have more than 100 rDNA
now have more than 100 rDNA products products
on the market
• A few examples of mutation occurring during A few examples of mutation occurring during
transfection, amplification, or cell expansion are known/reported
• Today we want to re‐examine what we know and what we might be concerned about in this plenary session, and there will be a workshop later to continue the discussions
Definition of Sequence Variants
• For today’s workshop session, sequence variants are molecules which are part of the heterogeneity of desired product with altered amino acid sequence arising from mutation, transcription errors, or mistranslation of the product coding sequence
product coding sequence • Sequence variants are not heterogeneity arising from chemical, biochemical, or biological events occurring after translation of mRNA for the desired molecule
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• We will use a broader definition during this plenary session, and some of our speakers will address sequence variants as
and some of our speakers will address sequence variants as well as other forms of heterogeneity