How do the Dako 22C3, Ventana SP263, and other immunohistochemistry platforms compare for PD‑L1 (programmed death‑ligand 1) testing?

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Last updated: May 15, 2026 • View editorial policy

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PD-L1 IHC Platform Comparison: 22C3, SP263, and Other Assays

The 22C3, 28-8, and SP263 assays demonstrate close analytical alignment and can be considered largely interchangeable for tumor cell scoring in NSCLC, while SP142 consistently stains fewer PD-L1 positive tumor cells and should not be used interchangeably with the other platforms. 1

Key Performance Characteristics by Platform

High Concordance Group (Interchangeable)

  • 22C3 (Dako): FDA-approved companion diagnostic for pembrolizumab
  • 28-8 (Dako): FDA-approved complementary diagnostic for nivolumab
  • SP263 (Ventana): CE mark only for NSCLC; demonstrated equivalency to 22C3 and 28-8

The Blueprint PD-L1 IHC Assay Comparison Project found these three assays showed comparable analytical performance with high concordance for tumor cell staining 1. Multi-institutional prospective studies confirmed strong correlation between 22C3, 28-8, and SP263, with Pearson correlation coefficients exceeding 0.93-0.96 1.

Low Concordance Outlier (Not Interchangeable)

  • SP142 (Ventana): Complementary diagnostic for atezolizumab
  • Consistently stained significantly fewer PD-L1 positive tumor cells compared to other assays 1
  • Scores both tumor cells (TC) and immune cells (IC) with different methodology
  • Should not be substituted for other assays

Platform-Specific Considerations

Scoring System Differences

Each assay uses distinct cutoffs and scoring methods 2:

  • 22C3: Three-tier system (TPS <1%, 1-49%, ≥50%)
  • 28-8: Qualitative percentage of tumor cells with membrane staining (cutoffs at 1%, 5%, 10%)
  • SP263: Equivalent to 22C3/28-8 scoring when properly validated
  • SP142: Unique TC/IC scoring (TC0-3, IC0-3) with combined assessment

Cross-Platform Validation

Critical finding: The 22C3 antibody can be successfully used on the Ventana platform (not just Dako) with proper validation, showing excellent concordance (ICC = 0.921, κ = 0.897) 1. This provides flexibility for laboratories already using Ventana equipment.

Recent clinical validation in the EMPOWER-Lung 1 study demonstrated 88% overall concordance between 22C3 and SP263 at the ≥50% cutoff, with similar clinical efficacy outcomes, confirming their interchangeability for patient selection 3.

Practical Clinical Algorithm

For NSCLC PD-L1 testing:

  1. First choice: Use 22C3 (required for pembrolizumab companion diagnostic) 1
  2. Acceptable alternatives: 28-8 or SP263 can substitute for 22C3 based on laboratory platform availability 1
  3. Laboratory-developed tests (LDTs): E1L3N clone shows high concordance with 22C3/28-8 when properly validated in CLIA-certified labs 1
  4. Avoid: Do not substitute SP142 for other assays due to lower sensitivity 1

Important Caveats

Immune Cell Staining

Concordance is poor for immune cell scoring across all platforms (ICC = 0.212) 1. This matters less for NSCLC where tumor proportion score (TPS) drives decisions, but is relevant for other tumor types using combined positive score (CPS).

Tumor Type Specificity

While concordance is good in NSCLC, data from other tumor types shows more variability:

  • Head and neck cancer: Moderate concordance (ICC 0.34-0.46) 4
  • Gastric cancer: Lower agreement, particularly at higher cutoffs 5
  • The assays were validated primarily in NSCLC; extrapolation to other cancers requires caution

Quality Control Requirements

All assays—whether FDA-approved or LDTs—require:

  • Proper validation with external quality control programs
  • Trained pathologist interpretation
  • Adherence to manufacturer protocols or validated alternative protocols 1

Regulatory Status Summary

  • 22C3: Only companion diagnostic (required for pembrolizumab first-line TPS ≥50%, second-line TPS ≥1%) 1
  • 28-8, SP142, SP263: Complementary diagnostics (aid selection but not required) 1
  • SP263 lacks FDA approval for NSCLC but has CE mark based on demonstrated equivalency 1

Bottom line for clinical practice: Use 22C3 when pembrolizumab is being considered. For other checkpoint inhibitors (nivolumab, atezolizumab), 28-8 or SP263 are acceptable alternatives to 22C3, but SP142 should only be used for its specific atezolizumab indication due to lower tumor cell staining sensitivity 1, 6.

References

4
Research

Comparison of three PD-L1 immunohistochemical assays in head and neck squamous cell carcinoma (HNSCC).

Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc, 2021

Related Questions

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.