This is a ready-to-use work instruction for the data review step that sits between an assay run and a reportable result, for vector copy number (VCN), potency, and replication competent virus (RCV) testing.
It is task level: the specific checks a reviewer performs, not the policy behind them. Replace every <<FILL: ...>> placeholder, set your document numbers, and route it through document control. A filled specimen follows. Verify each cited regulation against the current source. This is general guidance to adapt, not legal or regulatory advice.
Document control header
| Field | Entry |
|---|---|
| Document title | Vector Copy Number, Potency, and Replication Competent Virus Assay Data Review |
| Document number | <<FILL: WI-ID, e.g. WI-QC-041>> |
| Version | <<FILL: version>> |
| Effective date | <<FILL>> |
| Parent SOP | <<FILL: SOP-ID, e.g. audit trail review SOP and result invalidation SOP>> |
| Owner | <<FILL: role, e.g. QC Supervisor>> |
| Applies to | <<FILL: labs / instruments in scope>> |
Purpose and scope
This work instruction defines the step-by-step data review a qualified reviewer performs on VCN (typically by ddPCR or qPCR), cell-based potency, and RCV assay data before the result is used to support a release, comparability, or safety decision.
It applies in addition to, not instead of, the general audit trail review procedure and the result invalidation procedure referenced above.
1. VCN / titer data review
| Step | Action | Per-step acceptance |
|---|---|---|
| 1.1 | Confirm every acquisition or well run for the sample is present in the dataset, reported or explained | Count of acquisitions matches count of wells run; any missing acquisition has a documented reason |
| 1.2 | Confirm the amplitude or concentration threshold used is captured in the audit trail, including any edit, with the prior value, new value, and a stated reason | No unexplained threshold change; every change attributable and reasoned |
| 1.3 | Confirm no analysis was discarded without a retained record and a documented justification | Every analysis retained, whether reported or not |
| 1.4 | Confirm the transfer of the result into the LIMS or report matches the instrument value, via a verified interface or reconciled checksum, not manual retyping | Transferred value matches source value; transfer logged |
| 1.5 | Second person review of the audit trail, confirming steps 1.1 to 1.4, before the result is used for disposition | Documented second person review, dated, before use |
2. Potency assay data review
| Step | Action | Per-step acceptance |
|---|---|---|
| 2.1 | Confirm the reference standard lot used is current, within its qualification period, and its own qualification data are attributable | Reference standard traceable to a current, approved qualification record |
| 2.2 | Confirm curve fit or parallelism parameters, and any manual override of an automated fit, are captured in the audit trail with a reason | Every parameter change attributable and reasoned |
| 2.3 | Confirm a borderline, non-parallel, or rejected fit was retained with a documented explanation, not silently rerun until it passed | Every fit attempt retained; rerun only with documented, approved justification |
| 2.4 | Confirm system suitability or assay acceptance criteria were met before any sample result is accepted | Documented pass against pre-defined criteria |
| 2.5 | Second person review of the audit trail and the fit, before the result is used for disposition | Documented second person review, dated, before use |
3. Replication competent virus (RCV) data review
| Step | Action | Per-step acceptance |
|---|---|---|
| 3.1 | Confirm every replicate result is present and retained, including negative replicates | No missing or discarded replicates |
| 3.2 | Confirm positive and negative assay controls met their pre-defined acceptance criteria before any sample result is accepted as valid | Documented pass on both controls |
| 3.3 | Where any replicate is equivocal or reactive, confirm the escalation and investigation procedure was triggered, not a repeat of the assay without documented justification | Escalation record exists for every equivocal or reactive replicate |
| 3.4 | Confirm the final reportable result and its supporting replicate data are both retained and reconcile with each other | Reportable result traceable to the underlying replicate data |
| 3.5 | Second person, quality-function review of any RCV result before it supports release or a safety decision | Documented QA-level review, dated, before use |
4. Handling an exception
- Where any step above does not pass, stop; do not use the result for disposition.
- Notify the assay owner and Quality Assurance the same working day.
- Route through the result invalidation SOP if invalidation is being considered, or the deviation procedure per
<<FILL: SOP-ID>>if the exception reflects a broader process or system issue. - Do not repeat the assay pending investigation unless the investigation specifically concludes a repeat is scientifically justified and documents that justification in advance.
Records generated
| Field | Entry |
|---|---|
| Sample / lot ID | <<FILL>> |
| Assay type (VCN / potency / RCV) | <<FILL>> |
| Reviewer (name, date) | <<FILL>> |
| Steps completed | <<FILL: reference to checklist above>> |
| Exceptions | <<FILL: none, or list with detail>> |
| Second person / QA reviewer (name, date) | <<FILL>> |
References
21 CFR 211.194 (laboratory records); 21 CFR 211.192 (investigation of discrepancies). 21 CFR Part 11 (audit trail, electronic records). FDA Data Integrity and Compliance With Drug CGMP Q&A (final, Dec 2018). FDA guidance on potency testing and RCV/RCL testing considerations for gene therapy products; confirm current title and version before citing.
Confirm each reference against the current source before issue.
Filled specimen
| Field | Entry |
|---|---|
| Sample / lot ID | HRV-2026-0512 |
| Assay type | RCV (co-culture with amplification, per method <<FILL: method ID>>) |
| Reviewer | <<FILL: name>>, 2026-03-11 |
| Steps completed | 3.1 to 3.5 |
| Exceptions | One replicate (well 4) showed a reactive signal on first read. Escalated per step 3.3, investigated, confirmed as an assay artifact (positive control cross-contamination in adjacent well) per investigation <<FILL: number>>, repeat assay pre-approved and performed with clean layout, all replicates negative |
| Second person / QA reviewer | <<FILL: name>>, 2026-03-14 |
In this example a reactive replicate did not get quietly re-run. It was escalated, investigated to a documented root cause, and the repeat was pre-approved with its justification on record before it was performed. That sequence, and not the clean final result on its own, is what a reviewer checks.
How to adapt this work instruction
- Point the parent SOP reference to your actual audit trail review and result invalidation procedures.
- Adjust the acceptance criteria in each table to your validated method’s actual specifications.
- If your program runs additional CGT-specific assays (identity, sterility rapid methods, endotoxin), extend the same three-column pattern, action and per-step acceptance, rather than writing a separate ad hoc instruction for each.
- Confirm every regulation and guidance reference against the current published version before issue.