ISO 20166-2:2018

Overview

ISO 20166-2:2018 - Molecular in vitro diagnostic examinations - Part 2: Isolated proteins - specifies requirements and guidance for the pre-examination (pre-analytical) handling of formalin‑fixed, paraffin‑embedded (FFPE) tissue when the intended downstream testing targets isolated proteins. It covers documentation, specimen collection, transport, fixation, processing, protein isolation and storage during the pre‑examination phase for molecular in vitro diagnostics and molecular pathology. This part applies to laboratory‑developed tests, diagnostic labs, biobanks, IVD developers and regulatory bodies. Note: it is not applicable to protein evaluation by immunohistochemistry (IHC).

Key topics and technical requirements

• Scope and definitions: Clear terminology for FFPE workflows (e.g., pre‑examination phase, primary sample, cold ischemia, protein profile).
• Specimen collection and documentation: Requirements for donor/patient information, specimen metadata and processing history to support traceability and result interpretation.
• Transport and reception: Conditions and documentation for safe transport and logging of FFPE samples into the laboratory.
• Formalin fixation and embedding: Guidance on fixation with standard buffered formalin (NBF) (10 % formalin; formaldehyde ≈ 3.7 % mass fraction; pH 6.8–7.2) and downstream processing to preserve protein integrity.
• Cold ischemia considerations: Emphasis on minimizing time between tissue removal and stabilization to limit proteomic changes (see informative Annex A).
• Protein isolation procedures: Guidance on isolation of total protein from FFPE blocks, including use of commercial kits or laboratory‑developed protocols and the importance of heat‑induced reversal of formaldehyde crosslinks for successful protein recovery.
• Quality assessment and storage: Requirements for assessing isolated protein quality/stability and criteria for storage of extracts and FFPE materials.
• Applicability and exclusions: Clarifies that IHC is excluded and that local regulations may impose additional requirements.

Practical applications and users

ISO 20166-2:2018 is intended for:

• Clinical molecular pathology and medical laboratories performing molecular in vitro diagnostics.
• Developers and manufacturers of IVD assays and protein isolation kits for FFPE tissue.
• Biobanks and research institutions that collect, store and distribute FFPE samples for proteomic studies.
• Regulatory authorities and quality managers defining pre‑analytical SOPs for protein‑based assays.

Practical benefits include improved reproducibility of protein assays from FFPE tissue, better traceability, and reduced pre‑analytical variability affecting diagnostic and research proteomics.

Related standards

• ISO 15189:2012 - Medical laboratories - Requirements for quality and competence
• ISO 15190 - Medical laboratories - Requirements for safety
• ISO/IEC 17020:2012 - Conformity assessment - Inspection bodies

Keywords: ISO 20166-2:2018, FFPE, formalin-fixed paraffin-embedded, pre-examination, pre-analytical, isolated proteins, molecular in vitro diagnostics, molecular pathology, protein isolation, cold ischemia, buffered formalin.