Soonchunhyang University Hospital

Stereotactic body radiotherapy (SBRT) has been known to enhance the abscopal effect by up to 40% when delivered with immune checkpoint inhibitors (ICIs). Recently, preclinical and clinical studies demonstrate that metastatic lesions treated with non-cytotoxic low-dose radiotherapy (LDRT) significantly were reduced in the condition where SBRT and ICIs were administered together. Given that ICIs are highly expensive and some tumors are beyond the indications of ICIs, novel approaches are required to boost the abscopal effect in the absence of ICIs. Therefore, the investigators design a multicenter, randomized clinical trial that investigates the efficacy and safety of LDRT combined with SBRT in metastatic cancer patients. The primary endpoint is a lesion-specific response of LDRT lesions (i.e., abscopal effect) evaluated three months after radiotherapy.
Subjects will be randomly allocated into two groups (1:1) with the stratification by planning target volume and previous use of ICIs: control group (SBRT in three fractions) or experimental group (SBRT + LDRT in three factions). Unless patients agree with randomization, subjects will participate in a prospective cohort study.

In 2015, vonoprazan, a potassium-competitive blocker (P-CAB), was launched in Japan and used as an alternative for proton pump inhibitors (PPIs) for eradicating Helicobacter pylori. In recent studies, vonoprazan-based triple therapy significantly increased the eradication rate from 72.8% to 87.9%, compared to PPI treatment group. Accordingly, the Japanese Helicobacter treatment guidelines recommend prescribing P-CAB for eradication treatment. In 2018, a new P-CAB, tegoprazan, was developed in Korea and approved for gastric ulcer treatment. Subsequently, it was proven effective in the treatment of reflux esophagitis compared to PPIs in a non-inferiority clinical trial. P-CAB can increase the gastric pH to 6 or higher within 7 hours after taking tegoprazan. Because tegoprazan can be taken after meals, it can improve patient compliance for H. pylori eradication. Unlike vonoprazan in Japan, however, tegoprazan-based eradication in Korean population was similar to conventional PPI-based treatment. To date, the eradication success rates of PPI and tegoprazan-based triple therapy were 76.4-84.2% and 77.3-84.3%, respectively, and there was no significant difference between the two treatment groups.
Bismuth has long been used as a semi-metal in the dyspepsia and traveler's diarrhea. In H. pylori eradication therapy, several guidelines recommended the addition of bismuth to treatment regimens. Recently, bismuth was added to the 2-week triple regimen to increase the first-line H. pylori eradication rate in countries with high antibiotic resistance. The H. pylori eradication significantly increased from 87.5-88.1% to 95.8-97.3% in a recent study. The odds ratio was 1.63-2.18 in bismuth-added treatment group, compared to no use of bismuth group. In subgroup analysis, odd ratio was 1.66-2.22 in high clarithromycin-resistant areas. However, there was no comparative analysis of PPIs and tegoprazan in a bismuth-added triple therapy.