Standard Operating Procedure for Sterility Testing of Cell Banks in Biosimilar Production

1. Purpose

To establish a validated procedure for sterility testing of Master Cell Banks (MCB) and Working Cell Banks (WCB) used in biosimilar manufacturing, ensuring absence of microbial contamination as per regulatory standards.

2. Scope

This SOP applies to the QC Microbiology team responsible for performing sterility testing of cryopreserved cell banks intended for GMP production and regulatory filing.

3. Responsibilities

• QC Microbiologist: Performs sterility testing, records observations, and maintains test logs.
• QA Officer: Reviews and verifies the test results and ensures all documentation complies with GMP.

4. Accountability

The Head of Quality Control is accountable for ensuring sterility of cell banks used in manufacturing, following compendial guidelines (e.g., USP, Ph. Eur., IP).

5. Procedure

5.1 Test Material Preparation

1. Retrieve one vial each from the MCB and WCB under aseptic conditions.
2. Thaw and dilute cell suspension to 10 mL using sterile 0.9% saline or growth media.
3. Perform the test within 2 hours of thawing.

5.2 Media Preparation

1. Use two media types as per USP <71>:
   • Fluid Thioglycollate Medium (FTM)
   • Soybean Casein Digest Medium (SCDM)
2. Ensure sterility and growth promotion test (GPT) certification before use.

5.3 Inoculation Procedure

1. Inoculate 5 mL of test sample into 100 mL of FTM and 100 mL of SCDM under LAF.
2. Incubate FTM at 30–35°C and SCDM at 20–25°C for 14 days.
3. Include negative and positive controls.

5.4 Observation and Interpretation

1. Visually inspect media daily for turbidity, color change, or precipitates.
2. Record observations in Sterility Test Log (Annexure-1).
3. Interpret as:
   • Clear media → Negative (Sterile)
   • Turbid media → Positive (Contaminated)

5.5 Retesting and Reporting

1. If contamination is observed, initiate an Out of Specification (OOS) investigation.
2. Repeat sterility test with retained samples and environmental monitoring data.
3. Prepare Sterility Test Report (Annexure-2) after 14-day incubation.

6. Abbreviations

• MCB: Master Cell Bank
• WCB: Working Cell Bank
• USP: United States Pharmacopeia
• GPT: Growth Promotion Test

7. Documents

1. Sterility Test Log (Annexure-1)
2. Sterility Test Report (Annexure-2)

8. References

• USP <71> – Sterility Tests
• WHO TRS 978 – GMP for Biological Products
• ICH Q5D – Cell Substrate Guidelines

9. SOP Version

Version: 2.0

10. Approval Section

11. Annexures

Annexure-1: Sterility Test Log

Annexure-2: Sterility Test Report

Revision History: