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Evaluation of Viral Clearance Studies

Evaluation of Viral Clearance Studies. Mahmood Farshid, Ph.D. Div. Of Hematology OBRR/ CBER/FDA. Biologics . Monoclonal antibodies and recombinant products produced in cell culture Blood and blood products and other human derived products Animal derived products.

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Evaluation of Viral Clearance Studies

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  1. Evaluation of Viral Clearance Studies Mahmood Farshid, Ph.D. Div. Of Hematology OBRR/ CBER/FDA

  2. Biologics • Monoclonal antibodies and recombinant products produced in cell culture • Blood and blood products and other human derived products • Animal derived products

  3. Risk Reduction Strategies • Donor Screening: • donor history assessment, • written and oral questionnaire • Donors Testing: • Anti- HIV-1/2, HIV-1 p24 Ag ,anti-HCV, HBsAg , anti HBc, anti-HTLV-1/2, syphilis • (NAT for HCV and HIV) • Pharmacovigilance/ look back studies • Inactivation/Removal • Validating the manufacturing processes for removal / inactivation of viruses

  4. The Aim of Viral Validation • To provide evidence that the production process will effectively inactivate/remove viruses which could potentially be transmitted by the product • To provide indirect evidence that the production process has the capacity to inactivate/remove novel or yet undetermined virus contamination

  5. Virus inactivation: Chemical:organic solvents; pH extremes; solvent detergent; alcohol Physical: Heat treatment (dry heat or pasteurization) Virus removal Precipitation: ammonium sulfate etc. Chromatography: ion exchange; gel filtration; affinity; reverse phase Membrane filtration: Omega, Planova, DV50 Common Virus Clearance Methods

  6. Validation of Virus Removal/inactivation Include: • Scaling down process steps • Spiking appropriate steps with high titer of infectious virus (relevant or model) • Determining virus reduction factors for each step • Summing reduction factors to give a total log10 reduction value (LRV)

  7. Evaluation of the Effectiveness of Viral Clearance Step • Test viruses used • The design of the validation studies • The validity of scaled-down process • The kinetics of inactivation • Susceptibility to small variations in process parameters (robustness) • The limits of assay sensitivity • The log reduction achieved

  8. Virus Selection • Viruses that can potentially be transmitted by the product (relevant or specific model viruses) • Viruses with a wide range of physicochemical properties to evaluate robustness of the process (non-specific model viruses)

  9. Virus Selection • The nature of starting material • Cell lines • Human derived • Animal derived • Feasibility • Availability of a suitable culture system • Availability of high-titer stocks • Reliable methods for quantification

  10. Model viruses for human Blood-Derived Products Virus Model Envelope/ Size Resistance Genome (nm) HIV/HTLV HIV-1 Yes / RNA 80-130 Low HBV DHBV Yes / DNA ~ 40 Medium HCV BVDV Yes / RNA 40-50 Medium HAV HAV No / RNA 28-30 High CMV CMV/HSV Yes / DNA 150-200 Low-Med /PRV B19 PPV No / DNA 18-26 Very high

  11. Viruses Used to Validate Product Derived from Cell Lines Virus Genome Size(nm) Enveloped Resistance MVM ss-DNA 18-26 No Very high Reo-3 ds-RNA 60-80 No High MuLV ss-RNA 80-130 Yes Low PRV ds-DNA 150-200 Yes Low-med

  12. Virus Selection • DNA and RNA genome (single and double-stranded) • Lipid-enveloped and nonenveloped • Large, intermediate, and small size • From very highly resistant to inactivation to very • easily inactivated

  13. Scale-Down of Purification Steps • Usually 1/10 to 1/100 scale • Must keep buffers, pH, protein concentration, and product the same as full scale manufacturing • Must keep operation parameters as close to full scale as possible (e.g., bed height, flow rate) • Must show product is identical to production scale

  14. Criteria for An Effective Virus Clearance Step • Significant viral kill • Reproducible and controllable at process scale and model-able at the laboratory scale • Should have minimal impact on product yield and activity • Not generate neo-antigens or leave toxic residues

  15. GENERAL CONSIDERATIONS • Manufacturing processes for blood derived products should contain two effective steps for removal/inactivation of viruses • At least one step should be effective against non-enveloped viruses

  16. GENERAL CONSIDERATIONS(cont.) • At least one stage in a production process must inactivate rather than remove viruses • A single step having a large effect gives more assurance of viral safety than several steps having the same overall effect

  17. Limitations of Viral Validation Studies • Laboratory strains may behave differently than native viruses • Source plasma or Igs may have neutralizing antibodies • There may exist in any virus population a fraction that is resistant to inactivation • Scale-down processes may be differ from full-scale

  18. Limitations of Viral Validation Studies • Total virus reduction may be overestimated because of repeated and similar process steps • The ability of steps to remove virus after repeated use may vary

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