PD-L1 Expression in Non-clear cell Renal Cell Carcinoma
Menée sur des échantillons tumoraux prélevés sur 101 patients atteints d'un carcinome rénal autre que le type "à cellules claires", cette étude évalue l'association entre l'expression de PD-L1 et la survie
Background : Program Death Ligand-1 (PD-L1) expression in non-clear cell RCC (non-ccRCC) and its association with clinical outcomes are unknown.
Methods : Formalin-fixed paraffin-embedded (FFPE) specimens were obtained from 101 patients with non-ccRCC. PD-L1 expression was evaluated by immunohistochemistry in both tumor cell membrane and tumor infiltrating mononuclear cells (TIMC). PD-L1 tumor positivity was defined as ≥5% tumor cell membrane staining. For PD-L1 expression in TIMC, a combined score based on the extent of infiltrate and percentage of positive cells was used. Baseline clinico-pathological characteristics and outcome data [time to recurrence (TTR) and survival (OS)] were correlated with PD-L1 staining.
Results : Among 101 patients, 11 (10.9%) were considered PD-L1+ in tumor cells: 2/36 (5.6%) of chromophobe RCC, 5/50 (10%) of papillary RCC, 3/10 (30%) of Xp11.2 translocation RCC and 1/5 (20%) of collecting duct carcinoma. PD-L1 positivity (PD-L1+) in tumor cells was significantly associated with higher stage (p=0.01) and grade (p=0.03), as well as shorter OS (p<0.001). On the other hand, PD-L1 positivity by TIMC was observed in 57 (56.4%) patients: 13/36 (36.1%) of chromophobe RCC, 30/50 (60%) of papillary RCC, 9/10 (90%) of Xp11.2 translocation RCC and 5/5 (100%) of collecting duct carcinoma. A trend towards shorter OS was observed in pts with PD-L1+ in TIMC (p=0.08). PD-L1+ in both tumor cell membrane and TIMC cells were associated with shorter TTR (p=0.02 and p=0.03, respectively).
Conclusion : In non-ccRCC, patients with PD-L1+ tumors appear to have worse clinical outcomes, although only PD-L1 positivity in tumor cells is associated with higher tumor stage and grade.
Annals of Oncology , résumé, 2014