RT Journal Article SR Electronic T1 Association Between PD-L1 Expression and Efficacy of Chemoimmunotherapy in Extensive-stage Small Cell Lung Cancer JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 5531 OP 5539 DO 10.21873/anticanres.17379 VO 44 IS 12 A1 TSURUOKA, KENJIRO A1 TAMURA, YOSUKE A1 SHIMAZU, YASUYUKI A1 ARAI, MASAHIRO A1 MITSUYA, SHO A1 FUNAMOTO, TOMOYA A1 TSUJI, HIROYUKI A1 MATSUNAGA, NINSO A1 NAKAMURA, TAKAHIKO A1 IKEDA, SOICHIRO A1 KAWABATA, SHIGERU A1 IMAGAWA, AKIHISA A1 FUJISAKA, YASUHITO YR 2024 UL http://ar.iiarjournals.org/content/44/12/5531.abstract AB Background/Aim: Few studies have examined the association between programmed cell death ligand 1 (PD-L1) expression in small cell lung cancer and the effect of chemoimmunotherapy. Patients and Methods: Patients diagnosed with extensive-stage small cell lung cancer at our hospital between September 2019 and August 2023, who were treated with atezolizumab plus carboplatin and etoposide and had pathological tissue immunostained with SP142, were retrospectively examined to determine whether treatment efficacy differed depending on the expression of PD-L1. Results: Twenty-nine patients were analyzed. SP142 immunostaining revealed that the tumor cell (TC) score was 3, 2, 1, and 0 in 1, 0, 0, and 28 cases, respectively. The tumor-infiltrating cell (IC) score was 3, 2, 1, and 0 in 1, 0, 5, and 23 cases, respectively. The median progression-free survival (PFS) of the patients who tested positive and negative for TC was 13 and 5 months, respectively [hazard ratio (HR)=0.041; 95% confidence interval (CI)=0.000-36.225; p=0.109]; and the median overall survival (OS) was 13 and 7.5 months (HR=0.046; 95%CI=0.000-948.833; p=0.338), respectively. The median PFS of the patients who tested positive and negative for IC was 8 and 4 months, respectively (HR=0.216; 95%CI=0.061-0.765; p=0.004); the median OS was 15 and 8 months, respectively (HR=0.573; 95%CI=0.168-1.955; p=0.346). Conclusion: Patients who tested positive for IC had a significantly longer PFS than those who tested negative. Thus, PD-L1 expression may be a predictive factor of efficacy of chemoimmunotherapy in extensive-stage small cell lung cancer.