Abstract
The heterogeneity of programmed death-ligand 1 (PD-L1) status between core needle biopsies (CNBs) from one tumor has not been well studied before. The current study attempts to find out the best index using multiple core biopsies from one tumor which can better reflect the actual PD-L1 status. Random CNB was performed in surgical specimens from 170 consecutive non-small cell lung cancer samples. Fifty-one cases (41 cases with PD-L1 positive and 10 cases with PD-L1 negative) and 216 matched CNBs were analyzed by DAKO 22C3 PharmDx Link 48 Autostainer. The PD-L1 status was compared between the surgical specimens and matched CNBs. Heterogeneity of PD-L1 status between CNBs from one tumor was observed in 56% of PD-L1 positive cases. Different tumor proportion score (TPS) statistical forms with regard to the highest, mean, median, weighted average TPS, as well as TPS showed by the longest biopsy specimen and the biopsy with most tumor volume were compared. At a cut-off of 1%, the concordance rates were 94.1%, 88.2%, 90.2%, 86.3%, 86.3%, and 86.3%; At a cut-off of 50%, the concordance rates were 92.2%, 86.3%, 84.3%, 82.4%, 82.4%, and 86.3%, respectively. The CNB with the highest TPS can best represent PD-L1 status estimated by whole surgical specimen. The highest TPS among the multiple biopsies is a robust evaluation of the PD-L1 status, but not mean TPS, at the 1% and 50% cut-offs.
Highlights
The programmed death 1(PD-1) and programmed death-ligand 1(PD-L1) interaction acts as an immune checkpoint signal and is activated in many types of cancers, suppressing the function of activated T cells to identify and eliminate tumor cells
The core needle biopsies (CNBs) with the highest tumor proportion score (TPS) can best represent PD-L1 status estimated by whole surgical specimen
In 42 PD-L1 positive cases, one case was excluded for the matched biopsies were all necrosis. 15 biopsies were excluded for no tumor cells in the biopsies. 10 randomly PD-L1 negative cases were included, too (Fig. 1)
Summary
The programmed death 1(PD-1) and programmed death-ligand 1(PD-L1) interaction acts as an immune checkpoint signal and is activated in many types of cancers, suppressing the function of activated T cells to identify and eliminate tumor cells. PD-L1 allowed the cancer cells to evade the immune system in order to progress [15,16,17]. Pembrolizumab is an anti-PD-1 monoclonal antibody that was approved for treating advanced NSCLC based on PD-L1 expression in tumor cells (TCs). The KEYNOTE-010 trial demonstrated that pembrolizumab prolonged the overall survival of patients with a PD-L1 tumor proportion score(TPS) ≥ 1%[5], in which PD-L1was analyzed by immunohistochemistry (IHC). Accurate evaluation of PD-L1 expression is necessary for patients with advanced NSCLC
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