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PD-L1 expression in gastric and GEJ cancer patients treated with perioperative chemotherapy
The incidence, predictive and prognostic impact of PD-L1 expression in gastric and GEJ tumors treated with perioperative chemotherapy is poorly understood. Data regarding any possible modification on this expression after systemic treatment as well as the correlation between PD-L1 expression and treatment response are lacking.
We aimed to assess PD-L1 expression in pre-treatment biopsies samples and in the surgical specimens from patients with locally advanced gastric and GEJ tumors who received neoadjuvant treatment, evaluating its impact on pathological response and survival outcomes.
We retrospectively enrolled patients with gastric and GEJ tumors treated with perioperative chemotherapy and curative-intent resection in a single Brazilian cancer center between 2007 and 2017. Tumors of the gastric stump, Siwert I esophageal tumors, or treated with intraperitoneal chemotherapy were excluded. PD-L1 expression was assessed by IHC on biopsy samples and in a TMA build with the most representative areas of the surgical specimens. Results were analyzed using CPS score.
From 270 patients who met inclusion criteria, we were able to assess PD-L1 expression in at least one tissue sample from 155 subjects. The mean age was 58.4 years, all but 5 patients had clinical stage II or III disease and 90.3% completed the preoperative chemotherapy. A R0 resection was obtained in 96% of patients. Overall 60-day morbidity and mortality rates were 37.4% and 3.9%, respectively. A pCR was observed in 9.7% of cases while 45.8% experienced some degree of downstaging. The PD-L1 positivity rate was 20%. In 74 pared samples, a 21% discordance between PD-L1 expression in biopsy sample and surgical specimen was observed. With a median follow-up period of 60,3 months (95% CI 54.3 - 65.5), 5-years disease-free survival was 60,5% with a median overall survival not reached. ypT3-4 and ypN+ stages were both predictors of worse overall and disease-free survival. PD-L1 expression was neither associated with pathological response or survival outcomes.
We found that PD-L1 expression in the setting of locally advanced gastric tumors is relatively low and can vary considering the tissue sample analyzed. This expression had no correlation with survival outcomes in this population.
PD-L1 expression; gastric cancer; GEJ cancer
Trato gastrointestinal alto*
JACQUELINE NUNES DE MENEZES, HEBER SALVADOR DE CASTRO RIBEIRO, WILSON LUIZ DA COSTA JUNIOR, ALESSANDRO LANDSKRON DINIZ, ANDRE LUIS DE GODOY, IGOR CORREIA DE FARIAS, SILVIO MELO TORRES, TATIANE NEOTTI, MARIA DIRLEI F S BEGNAMI, FELIPE JOSÉ FERNANDEZ COIMBRA