Schlafen 11 Expression in Patients With Small Cell Lung Cancer and Its Association With Clinical Outcomes.

Background: Schlafen 11 (SLFN-11) has been identified as a sensitizer of tumor cells to DNA-damaging agents. However, the relationship between SLFN-11 expression and clinical outcomes in patients with small cell lung cancer (SCLC) remains unexplored. Thus, we aimed to evaluate the impact of SLFN-11 expression on survival in patients with limited-stage (LS) SCLC.

Methods: We conducted a retrospective review of data from patients pathologically diagnosed with LS-SCLC post-surgery between January 2008 and December 2018. SLFN-11 expression was assessed using immunohistochemistry in tissue microarrays and scored using a histology (H)-score (range: 0-300).

Results: Overall, 86 patients were included in the analysis with a median H-score of 43 for SLFN-11 expression. Among the patients, 44 had high SLFN-11 expression (provisionally defined as H-score ≥ 43). No significant differences in clinical profiles were observed between the two groups (high and low SLFN expression). The median survival durations were not reached (NR; 95% confidence interval [CI]: 65.1 months to NR) and 33.5 months (95% CI: 24.2 months to NR) for patients with high and low SLFN-11 expression, respectively (hazard ratio [HR]: 0.40, 95% CI: 0.19-0.81; p = 0.012). Among patients who relapsed post-surgery (n = 21), the median survival durations were 22.0 (95% CI: 7.6-44.9 months) and 8.1 (95% CI: 1.8-24.6 months) months in patients with high and low SLFN-11 expression, respectively (HR: 0.22, 95% CI: 0.06-0.84; p = 0.026).

Conclusions: High SLFN-11 expression is associated with relatively longer survival in patients with LS-SCLC in both those undergoing surgery and those who have relapsed.