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Poster Discussion session - Head and neck cancers

2434 - Comparison of Patient Populations Identified by Different PD-L1 Assays in Head and Neck Squamous Cell Carcinoma (HNSCC)

Date

20 Oct 2018

Session

Poster Discussion session - Head and neck cancers

Topics

Translational Research

Tumour Site

Head and Neck Cancers

Presenters

Marietta Scott

Citation

Annals of Oncology (2018) 29 (suppl_8): viii372-viii399. 10.1093/annonc/mdy287

Authors

M. Scott1, S. Wildsmith2, M. Ratcliffe3, H. Al-Masri4, P.W. Scorer5, C. Barker6, M.C. Rebelatto7, J. Walker8

Author affiliations

  • 1 Imed Biotech Unit, Precision Medicine Laboratories, Precision Medicine and Genomics, Astrazeneca, CB4 0FZ - Cambridge/GB
  • 2 Imed Biotech Unit, Oncology Companion Diagnostics Unit, Precision Medicine and Genomics, Astrazeneca, CB4 0FZ - Cambridge/GB
  • 3 Imed Biotech Unit, Oncology Companion Diagnostics Unit, Precision Medicine and Genomics, Astrazeneca, SK10 4TG - Cambridge/GB
  • 4 Anatomic Pathology & Clinical Pathology, Hematogenix, Tinley Park/US
  • 5 Imed Biotech Unit, Precision Medicine Laboratories, Precision Medicine and Genomics, Astrazeneca, Cambridge/GB
  • 6 Imed Biotech Unit, Precision Medicine Laboratories, Precision Medicine and Genomics, Astrazeneca, CB10 1XL - Cambridge/GB
  • 7 Experimental Pathology, Translational Sciences-research, MedImmune, Gaithersburg/US
  • 8 Imed Biotech Unit, Oncology Companion Diagnostics Unit, Precision Medicine and Genomics, Astrazeneca, CB4 - Cambridge/GB
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Resources

Abstract 2434

Background

Establishing the concordance of commercially available PD-L1 assays and scoring algorithms in HNSCC is essential to understand potential differences in selected patient populations in the clinic and in immunotherapy clinical trials.

Methods

Four immunohistochemistry (IHC) assays: VENTANA PD-L1 (SP263), VENTANA PD-L1 (SP142), PD-L1 IHC pharmDx 22C3 (Agilent) and PD-L1 IHC pharmDx 28-8 (Agilent) were used to stain 486 HNSCC samples. In a new analysis of previously stained samples (Ratcliffe Ann Onc 2016;27:955D), all slides were scored by a single pathologist to eliminate inter-reader variability. Positive (PPA), negative (NPA) and overall (OPA) percent agreement are newly reported between various tumour cell (TC), immune cell (IC) and combined positive score (CPS) cutoffs.

Results

SP263, 22C3 and 28-8 assays showed good analytical correlation for TC staining (Spearman’s rank correlation coefficient 0.75–0.83). Correlation was lower for ICs (Spearman’s coefficient 0.66–0.77). OPAs for these 3 assays ranged from 59%–93% at various matched algorithms (Table). The VENTANA PD-L1 (SP263) assay appeared more sensitive, assigning a higher proportion of patients as PD-L1 high, resulting in low PPA for 28-8 and 22C3. Moderate classification agreement was seen between different scoring algorithms. OPA for 22C3 CPS≥1 and CPS≥10 vs 28-8 TC≥1% was 84% and 76%; and between SP263 TC≥25% and 22C3 CPS≥1 or CPS≥10, 61% and 84%, respectively.Table: 1051PD

Assay agreement with VENTANA SP263 at matched cutoffs

PD-L1 IHC pharmDx 22C3PD-L1 IHC pharmDx 28-8VENTANA PD-L1 SP142
Cut-offOPA (%)NPA (%)PPA (%)OPA (%)NPA (%)PPA (%)OPA (%)NPA (%)PPA (%)
TC ≥ 1%7995688495775910031
TC ≥ 25%91995693100628510015
IC ≥ 25%82974181964174996
CPS≥1759368839678699957
CPS≥107998558499646810026
TC ≥ 25% / IC ≥ 25%799748809653759737

Conclusions

Lower agreement of PD-L1 assays was observed for HNSCC than for other indications (Ratcliffe Cancer Res 2016;76:LB-094; Zajac J Immunother Cancer 2017;5:P104). Significant differences in patient classification are observed when comparing the different clinical algorithms. In HNSCC, caution should be exercised interpreting efficacy data derived with different algorithms. Understanding how to correct for differences in PD-L1 sensitivity is required before interchanging assays.

Clinical trial identification

Legal entity responsible for the study

AstraZeneca.

Funding

AstraZeneca.

Editorial Acknowledgement

Editorial assistance was provided by Sheila Benson from PAREXEL (Hackensack, NJ, USA) in accordance with Good Publication Practice (GPP3) guidelines, funded by AstraZeneca.

Disclosure

M. Scott, S. Wildsmith, P.W. Scorer, C. Barker, J. Walker: Employee and shareholder: AstraZeneca. M. Ratcliffe: Consultant: AstraZeneca. H. Al-Masri: Employee: Hematogenix. M.C. Rebelatto: Employee: MedImmune.

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