Level of circulating PD-L1 expression in patients with advanced gastric cancer and its clinical implications

Objective：The programmed cell death-1 receptor/programmed cell death-1 ligand （PD-1/PD-L1） pathway plays a crucial role in tumor evasion from host immunity.This study was designed to evaluate the association between circulating PD-L1 expression and prognosis in patients with advanced gastric cancer.Methods：Totally 80 advanced gastric cancer patients and 40 health controls from Beijing Cancer Hospital were enrolled in the present study.Circulating PD-L1 expression was tested by enzymelinked immunosorbent assay （ELISA）.The associations between the expression level of PD-L1 and clinicopathological features and prognosis were analyzed statistically.Results：Expression of PD-L1 in advanced gastric cancer patients was significandy up-regulated compared with health people （P=0.006）.The expression of PD-L1 was significantly correlated with differentiation and lymph node metastasis （P=0.026 and P=0.041,respectively）.Although we didn＇t find significant difference in all advanced gastric cancer patients with different PD-L1 expression,the adenocarcinoma patients with higher up-regulated PD-L1 expression had much better prognosis than low expression patients （65.6％ vs.44.7％,P=0.028）.Conclusions：PD-L1 was elevated in advance gastric cancer patients and may play an important role in tumor immune evasion and patients prognosis.

Preparation, identification, and clinical application ofanti-HBs monoclonal antibody that binds both wild-typeand immune escape mutant HBsAgs

Using a standard cellular fusion technique and indirect enzyme-linked immunosorbent assay(ELISA),a hybridoma cell line strain secreting anti-HBs monoclonal antibody(mAb)(defined G6 mAb)was obtained.The cells grew and secreted mAb stably.Antibody titers in the culture supernatant and ascites were 2.048�106 and 4.096�106,respectively.By applying the anti-HBs G6 mAb and horseradish peroxidase(HRP)-labeled goat anti-HBs antibody,we developed a sandwich ELISA(defined G6m ELISA)for detecting both wild-type and immune escape mutant HBsAgs(IEM HBsAg).The assay was performed to detect 17 species of genome recombinant expression HBsAg,including two wild-type species and 15 IEM HBsAg species,which varied in the“a”determinant,in a group of patients infected with hepatitis B virus(HBV).The patients previously had a lower ELISA detection signal[(absorbance of patients/absorbance of normal people(P/N):1.0–4.5)].The results demonstrated that the sensitivity of this assay to wild-type HBsAg was no less than 0.125μg/L;12 of 15 IEM HBsAg species(P/N≥2.5)were positive for G6 mAb.Of the positive IEM HBsAg species,two had a low absorbance value at 450 nm(A450),one had an intermediate A450 value and nine had a high A450 value,which was 7.55%(mean),59.4%and 92.1%–109.4%of the wild-type A450 value,respectively.The two species with low A450 value and the three negative species mutated at the bases 120–124 in thefirst loop of the HBV“a”determinant.Using the G6 ELISA and two commercial ELISA kits(A and B),177 patients were tested.The G6 ELISA had a significantly higher detection rate than either commercial ELISAs(19.21%vs 14.89%and 6.21%,respectively;P<0.01,P<0.05,respectively).