PD-L1 expression in melanoma shows marked heterogeneity within and between patients: implications for anti-PD-1/PD-L1 clinical trials
A partir d'échantillons de tumeurs primitives et de métastases prélevés sur 58 patients atteints d'un mélanome métastatique, cette étude identifie une hétérogénéité de l'expression de PD-L1 entre les patients et, pour la majorité des patients, une différence d'expression de PD-L1 dans les tumeurs primitives et dans les métastases
This study evaluated expression of PD-L1 in immunotherapy-naïve metastatic melanoma patients to determine longitudinal intra-patient concordance and correlate PD-L1 status with clinicopathologic characteristics and outcome. PD-L1 expression was assessed by immunohistochemistry in 58 patients (43 primary tumors, 96 metastases). Seventy-two percent of patients had at least one specimen expressing PD-L1 in ≥1% of tumor cells. Median positive tumor cell count overall was low (8% in non-zero specimens). PD-L1 expression was frequently discordant between primary tumors and metastases, and between intra-patient metastases, such that 23/46 longitudinal patient specimens were discordant. PD-L1 was associated with higher TIL-grade but not with other known prognostic features. There was a positive univariate association between PD-L1 expression in locoregional metastases and melanoma specific survival but the effect was not observed for primary melanoma. In locoregional lymph node metastasis PD-L1+/TIL+ patients had the best outcome and PDL1+/TIL- patients had poor outcome. This article is protected by copyright. All rights reserved.
Pigment Cell & Melanoma Research , résumé, 2013