IADR Abstract Archives
Immunohistochemistry Analysis of PD-L1 Expression in Head and Neck Cancer
Objectives: PD-L1 reactivity by immunohistochemistry has been associated with clinical response to anti-PD-L1 therapy. Studies have shown that the Combined Positive Score (CPS) is more sensitive than other Pathologic Scores (TPS) due to the inclusion of inflammatory cells (CPS >1). Standardization of CPS interpretation is more complex than other scores and different antibodies.
Describe the correlation in the interpretation of CPS between pathologists.
Methods: We analyzed tissue microarray of 40 samples of HNCSCC from Fundacion Santa Fe de Bogotá cohort InterCHANGE-Headspace for PD-L1 Dako 22C3 antibody by immunohistochemistry. PD-L1 was calculated using the Combine Proportion Score (CPS) by two pathologist and CPS concordance was analyzed by range (<1, 1-19 or >20) vs (negative <1 Vs positive >1)
Results: 40 tumor samples, 22 from oral cavity (OC), 6 from larynx (LA), 1 metastasis of unknown primary (MUP) and 11 from oropharynx (OP), corresponding to 15 female and 25 male with an average age of 66-y were analyzed by two expert pathologist using CPS. 6 cases were excluded due to no infiltrating carcinoma present.
When CPS was grouped by range (<1, 1-19 and >20) 79, 4 % (n=27) of cases were concordant and 7 (n=20,5), discordant. When CPS was grouped by positive (>1) Vs negative (<1) concordance was 100% among the two expert pathologist corresponding to 6 negative cases (17,6%) and 28 positives (82,3%).
Conclusions: In our cohort PD-L1 expression positivity was 82% in HNSCC as reported in the literature. Concordance was greater when used cutoff point of 1 Vs ranges. Standardization of interpretation, training and expertise of pathologist is crucial for patients who are most likely to benefit from this type of treatment.
Describe the correlation in the interpretation of CPS between pathologists.
Methods: We analyzed tissue microarray of 40 samples of HNCSCC from Fundacion Santa Fe de Bogotá cohort InterCHANGE-Headspace for PD-L1 Dako 22C3 antibody by immunohistochemistry. PD-L1 was calculated using the Combine Proportion Score (CPS) by two pathologist and CPS concordance was analyzed by range (<1, 1-19 or >20) vs (negative <1 Vs positive >1)
Results: 40 tumor samples, 22 from oral cavity (OC), 6 from larynx (LA), 1 metastasis of unknown primary (MUP) and 11 from oropharynx (OP), corresponding to 15 female and 25 male with an average age of 66-y were analyzed by two expert pathologist using CPS. 6 cases were excluded due to no infiltrating carcinoma present.
When CPS was grouped by range (<1, 1-19 and >20) 79, 4 % (n=27) of cases were concordant and 7 (n=20,5), discordant. When CPS was grouped by positive (>1) Vs negative (<1) concordance was 100% among the two expert pathologist corresponding to 6 negative cases (17,6%) and 28 positives (82,3%).
Conclusions: In our cohort PD-L1 expression positivity was 82% in HNSCC as reported in the literature. Concordance was greater when used cutoff point of 1 Vs ranges. Standardization of interpretation, training and expertise of pathologist is crucial for patients who are most likely to benefit from this type of treatment.