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Updated: Dec 13, 2025

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Published on: January 16, 2019

A general evidence-based sequence variant control limit for recombinant therapeutic protein development.

Aming Zhang¹, Zhengwei Chen¹, Meinuo Li¹

¹Analytical Chemistry, Regeneron Pharmaceuticals, Inc ., Tarrytown, New York, USA.

|August 4, 2020

Summary

Sequence variants (SVs) in therapeutic proteins can affect drug safety and efficacy. A 0.1% control limit at individual amino acid sites is proposed to manage SV risks during biologic development.

Keywords:

Amino acid depletion Chinese hamster ovary cell line amino acid misincorporation control limit critical quality attributes mammalian cell culture mass spectrometry monoclonal antibody sequence variant therapeutic protein

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Published on: March 25, 2020

Area of Science:

Biopharmaceutical development
Protein engineering
Drug safety and efficacy

Background:

Sequence variants (SVs) are unintended amino acid substitutions in therapeutic proteins.
SVs can impact protein efficacy and patient safety, gaining regulatory attention.
High fidelity of mammalian expression systems usually keeps SVs low, but process deviations can increase them.

Purpose of the Study:

To address the lack of established guidance for assessing and managing SV risks in biologics.
To determine acceptable SV levels during product and process development without compromising drug safety and efficacy.
To propose a general control limit for SVs in biologic development.

Main Methods:

Comprehensive sequence variant analysis.
Extensive literature review.
Benchmark survey of approved therapeutic proteins.
Analysis of accumulated SV control practices.

Main Results:

A general sequence variant (SV) control limit of 0.1% at individual amino acid sites is proposed.
This limit is justified by literature, industry benchmarks, and practical experience.
The proposed limit aims to guide biologic development and manage SV risks effectively.

Conclusions:

Establishing clear SV control limits is crucial for biologic development.
The proposed 0.1% limit provides a benchmark for managing SVs.
This approach supports the development of safe and effective therapeutic proteins.