ABSTRACT
Purpose@#The optimal tumor mutational burden (TMB) value for predicting treatment response to programmed cell death-1 (PD-1) checkpoint inhibitors in advanced gastric cancer (AGC) remains unclear. We aimed to investigate the optimal TMB cutoff value that could predict the efficacy of PD-1 checkpoint inhibitors in AGC. @*Materials and Methods@#Patients with AGC who received pembrolizumab or nivolumab between October 1, 2020, and July 27, 2021, at Samsung Medical Center in Korea were retrospectively analyzed. The TMB levels were measured using a next-generation sequencing assay. Based on receiver operating characteristic curve analysis, the TMB cutoff value was determined. @*Results@#A total 53 patients were analyzed. The TMB cutoff value for predicting the overall response rate (ORR) to PD-1 checkpoint inhibitors was defined as 13.31 mutations per megabase (mt/Mb) with 56% sensitivity and 95% specificity. Based on this definition, 7 (13.2%) patients were TMB-high (TMB-H). The ORR differed between the TMB-low (TMB-L) and TMB-H (8.7% vs. 71.4%, P=0.001). The progression-free survival and overall survival (OS) for 53 patients were 1.93 (95% confidence interval [CI], 1.600–2.268) and 4.26 months (95% CI, 2.992–5.532). The median OS was longer in the TMB-H (20.8 months; 95% CI, 2.292–39.281) than in the TMB-L (3.31 months; 95% CI, 1.604–5.019; P=0.049). @*Conclusions@#The TMB cutoff value for predicting treatment response in AGC patients who received PD-1 checkpoint inhibitor monotherapy as salvage treatment was 13.31 mt/Mb.When applying the programmed death ligand-1 status to TMB-H, patients who would benefit from PD-1 checkpoint inhibitors can be selected.
ABSTRACT
Purpose@#Rearranged during transfection (RET) gene rearrangement is a well-known driver event in non–small cell lung cancer (NSCLC). Pralsetinib is a selective inhibitor of RET kinase and has shown efficacy in oncogenic RET-altered tumors. This study evaluated the efficacy and safety of expanded access program (EAP) use of pralsetinib in pretreated, advanced NSCLC patients with RET rearrangement. @*Materials and Methods@#Patients who received pralsetinib as part of the EAP at Samsung Medical Center were evaluated through a retrospective chart review. The primary endpoint was overall response rate (ORR) per the Response Evaluation Criteria in Solid Tumors (RECIST) ver. 1.1 guidelines. Secondary endpoints were duration of response, progression-free survival (PFS), overall survival (OS), and safety profiles. @*Results@#Between April 2020 and September 2021, 23 of 27 patients were enrolled in the EAP study. Two patients who were not analyzed due to brain metastasis and two patients whose expected survival was within 1 month were excluded from the analysis. After a median follow-up period of 15.6 months (95% confidence interval [CI], 10.0 to 21.2), ORR was 56.5%, the median PFS was 12.1 months (95% CI, 3.3 to 20.9), and the 12-month OS rate was 69.6%. The most frequent treatment-related adverse events (TRAEs) were edema (43.5%) and pneumonitis (39.1%). A total of 8.7% of patients experienced extra-pulmonary tuberculosis. TRAEs with a common grade of three or worse were neutropenia (43.5%) and anemia (34.8%). Dose reduction was required in nine patients (39.1%). @*Conclusion@#Pralsetinib presents a clinical benefit when used in patients with RET-rearranged NSCLC, consistent with a pivotal study.