With increased challenges in downstream purification of biomolecules, standard adsorbents often cannot achieve the purity required. At Astrea Bioseparations Ltd. ('Astrea') we have over 30 years of experience in developing custom affinity ligands and adsorbents that can help achieve safe and effective biotherapeutics. This article describes the various phases needed for the development of a custom affinity adsorbent suitable for GMP manufacture.
Ligand Discovery Projects commence with the development and implementation of high throughput assays for quantification of target biomolecule and impurities to be removed. Typical assays developed include ELISA, SDS-PAGE, HPLC, total protein and functional activity assays.
Option 1 - Known receptor structure: Using rational design, molecular docking and virtual
screening to help identify possible sites for ligand binding and potential ligand structures.
Option 2 - Known ligand structure: Ligand selection from Astrea’s Chemical Combinatorial
Library CCL® containing over 100,000 triazine based compounds to provide a focused library for initial screening Focused design based on ligands showing early “activity” against a target.
Option 3 - No prior knowledge of receptor or binding ligands: Selection of binding ligands by screening general ligand libraries comprising diverse ligand structures distributed across a broad region of chemical space.
Adsorbents synthesised in library format (PuraPlate™ 96 column block) with ligand structures identified from initial design/virtual screening studies.
High throughput evaluation of existing general ligand libraries and newly designed libraries. Non-bound, wash, elution and CIP procedures investigated.
Scale-up synthesis and verification chromatography of lead candidates (identified during library screening). Performed using automated chromatography workstations and packed columns with initial investigation of non-bound, wash, elution and CIP steps.
Includes evaluation of:
- Base matrices;
- Ligand synthesis method;
- Immobilised ligand densities;
- Attachment chemistry (e.g. spacer arms).
Optimisation of adsorbent manufacture and production of written methods in readiness for transfer to Astrea’s manufacturing facility.
Optimisation of process conditions (i.e. load, wash, elution and CIP steps) to utilise the adsorbent in the most efficient way and maximise product purity and yield. Performed in parallel to Adsorbent Development An adsorbent cleaning and re-use study may be
performed as part of this work.
Tech Transfer & Validation
Procedures for manufacture of the custom adsorbent will be transferred to Astrea's manufacturing facility situated on the Isle of Man, British Isles. Trial lot(s) are usually made at the 1 litre scale prior to validation of the manufacturing process by production of three conformance batches of custom adsorbent Manufactured batches will be tested for their ability to achieve the process performance defined specifications Samples of the batches of custom adsorbent produced during the validation process will be supplied to the end user
A validation plan and summary report will be produced as a part of this activity.
A comprehensive support package of information will be developed and supplied to the end user to assist registration of the purification process with regulatory authorities. The regulatory package will include information derived from the following studies (additional testing and documentation can be included on request):
a) LIGAND LEAKAGE STUDY - Including a forced degradation study under extreme conditions.
b) STABILITY TRIALS - Under a range of normal and extreme conditions, up to one year duration.
c) TOXICOLOGY STUDIES - MTD in vivo and Standard WHO AMES tests.
To find out more contact us at [email protected]
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