Advisory Committeefor Pharmaceutical Science

Process Analytical Technologyand Biotechnology Products

Keith O. Webber, Ph.D.Office of Biotechnology ProductsOPS/CDER

April 13, 2004

Which Products?Blood and Blood ProductsVaccinesAllergenic ProductsCell TherapiesGene TherapiesRecombinant DNA-derived Protein ProductsBiological Products include:

Which Products?Blood and Blood ProductsVaccinesAllergenic ProductsCell TherapiesGene TherapiesRecombinant DNA-derived Protein ProductsBiological Products include:

Two Aspects of PATMonitoring product characteristics or surrogates.

Monitoring and modulating critical process parameters to guide the product characteristics during processing.

Process Analytical TechnologyDataProcessDecisionMonitorAdjustEvaluate

Biotechnology ProcessesFermentationConcentrationHarvestingProduct CaptureChromatographyFiltrationFormulationLyophilization

Biotech API CharacteristicsPrimary structure (amino acid sequence)Secondary structure(local interactions)

Biotech API CharacteristicsTertiary structure (domain interactions)

Quaternary structure(subunit interactions)

Biotech API CharacteristicsPost-translational modifications:GlycosylationProteolysisAcylationSulfationmany others

Biotech Product CharacteristicsImpurity profile:Process-related impuritiesMedia componentsHost cell proteinsLeachatesProduct-related impuritiesTruncationsmis-foldingsaggregates

Analytical MethodsPrimary StructureMethods:amino acid analysisprotein sequencingpeptide mappingmass spectrometryimmunoassay

Analytical MethodsSecondary StructureMethods:circular dichroismNMR

Analytical MethodsTertiary & Quaternary StructureMethods:Functional assayImmunoassayPeptide mapping (for mapping disulfides)Size-exclusion chromatographyHydrophobic-interaction chromatography

Analytical MethodsPost-translational ModificationsEnzymatic cleavage & analysisMass spectroscopyNMRImmunoassayPeptide mapping Functional assay

Inherent ChallengesBiotech products are large, complex, plieotropic molecules - mixture of post-translational modifications- multiple active sites- homologous- heterologous- activities are dependent on complex, folded conformations- susceptible to multiple degradative events- proteolysis, aggregation, mis-folding, oxidation, deamidation, etc.

Factors to Consider

PurityPotencyStrengthPharmacokineticsPharmacodynamicsImmunogenicity

Fermentation ProcessesMonitor: AgitationpHIonic strengthTemperatureDissolved O2 & CO2Media componentsBiomassBioburden (sterility, mycoplasma)Light absorbance (e.g., A280)Control: AgitationpHIonic strengthTemperatureDissolved O2 & CO2Media components

Growth rateExpression rate

Chromatographic ProcessesMonitor: pHIonic strengthFlow rateTemperatureVolumeBioburdenLight absorbance

Control: pHIonic strengthFlow rateTemperatureVolume

Filtration ProcessesMonitor: TemperatureFlow rateBack-pressureVolume BioburdenLight absorbanceControl: TemperatureFlow rateBack-pressureVolume

LyophilizationMonitor: Shelf temperatureProduct temperatureChamber PressureCondenser temperatureCondenser pressureTimeControl: Shelf temperatureProduct temperatureChamber PressureCondenser temperatureCondenser pressureTime

Freezing rateDrying rateProduct moisture content

QuestionsWhat technologies are available now to evaluate the characteristics of protein products in real time during manufacturing?What tools would allow us to understand the manufacturing process better?What processes in biological drug manufacturing would benefit the most from implementation of PAT?For processes or products that do not currently allow direct product quality monitoring, what other strategies do you recommend for product quality control in addition to control of in-process parameters? What additional elements should be incorporated in a training and certification program for reviewers and inspectors of biotechnology PAT applications?