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.

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.

Purpose: Alectinib and brigatinib are second-generation anaplastic lymphoma receptor tyrosine kinases (ALKs) that are widely used as first-line therapy for treating ALK-positive advanced non–small cell lung cancer (NSCLC). Given the lack of a head-to-head comparison of these drugs as first-line therapies, this retrospective observational study aimed to compare the real-world efficacy and safety of alectinib and brigatinib. Materials and Methods: Patients who received alectinib or brigatinib as the first-line treatment for ALK-positive advanced NSCLC were evaluated for clinical outcomes of objective response rate (ORR), intracranial ORR, time to next treatment (TTNT), progression-free survival (PFS), overall survival (OS), and safety profiles. Results: Of 208 patients who received either alectinib or brigatinib as a first-line treatment, 176 received alectinib and 32 received brigatinib. At the data cutoff point, the median follow-up duration was 16.5 months (95% confidence interval [CI], 14.7 to 18.3) in the brigatinib group and 27.5 months (95% CI, 24.6 to 30.4) in the alectinib group. The ORR was 92.5% with alectinib and 93.8% for brigatinib. The intracranial ORR rates were 92.7% (38/41) and 100% (10/10), respectively. The rate of PFS at 12 months was comparable between the alectinib group and the brigatinib groups (84.4% vs. 84.1%, p=0.64), and the median TTNT, PFS, and OS were not reached in either group. Treatment-related adverse events were usually mild, and treatment discontinuation due to adverse events was rare (alectinib 4.5% vs. brigatinib 6.25%). Conclusion Alectinib and brigatinib had similar clinical benefits when used as the first-line treatment of NSCLC patients with ALK rearrangement in the real world.