PD-L1 expression tied to favourable prognosis in SCLC
medwireNews: Programmed death-ligand 1 (PD-L1) is expressed by around 70% of small-cell lung cancers (SCLC) and is associated with favourable patient outcomes, Japanese researchers report.
Writing in the Journal of Thoracic Oncology, Koichi Azuma (Kurume University, Fukuoka) and study co-authors say that PD-L1 expression is associated with limited disease and is an independent predictor of better overall survival.
While further work is needed to clarify why these factors are associated with PD-L1 expression, the researchers believe that their data “provide a basis for implementation of cancer immunotherapy in patients with SCLC.”
PD-L1 is expressed by T-cells and helps tumours to elude immune surveillance and eradication. The use of monoclonal antibodies directed against PD-L1, known as “immune checkpoint blockade,” is a promising therapeutic strategy in oncology and has shown antitumour efficacy in NSCLC.
To evaluate the role of PD-L1 in SCLC, Azuma’s team used immunohistochemistry to assess tumour samples from 102 patients. In all, 73 (71.6%) patients tested positive for PD-L1, defined as more than 5% of tumour cells stained.
When patients were divided according to PD-L1 status, PD-L1–positive patients had significantly longer overall survival than PD-L1–negative patients (median; 16.3 vs 7.3 months).
In univariate analysis, PD-L1 expression was one of several factors that predicted a better overall survival, along with limited disease stage, good performance status, low serum levels of neuron-specific enolase and normal serum levels of lactate dehydrogenase.
Performance status, limited disease stage and PD-L1 expression emerged as significant and independent predictors of overall survival in multivariate analysis, with adjusted hazard ratios of 0.39, 0.40 and 0.44, respectively.
Also, among the subgroup of patients with extensive disease, PD-L1–positive patients had a longer overall survival than the PD-L1–negative group (median 9.2 vs 5.4 months).
Noting that the clinicopathological characteristics associated with PD-L1 expression in SCLC are largely unknown, Azuma and colleagues call for future work to develop a standardised quantitative assay for PD-L1 expression and to examine the interaction of chemotherapy with PD-L1 expression.
“Further studies are warranted to clarify the role of PD-L1 expression, and the therapeutic effect of PD-1/PD-L1 blockade in SCLC models and clinical trials,” they add.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2014
By Joanna Lyford, Senior medwireNews Reporter