Clinical Research Directory

Abscopal Effect from Low-dose Radiotherapy in Metastatic Cancer Combined with Stereotactic Body Radiotherapy

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.

Abscopal Effect from the Low-dose Radiotherapy in Polymetastatic Cancer Patients Receiving Stereotactic Radiotherapy

Recently, MD Anderson Cancer Center reported the phase II trial to investigate high-dose radiotherapy (HDRT, 20-70 Gy) and low-dose radiotherapy (LDRT, 1-10 Gy) for metastatic cancer patients who had undergone immunotherapy. HDRT or HDRT+LDRT was conducted in two respective groups and the treatment group was determined according to the disease status of participants, not randomization. Immunotherapy was maintained in this clinical study. Therefore, we aim to investigate this abscopal effect from adding LDRT to HDRT, irrespective of previous immunotherapy, in this multicenter, single-arm study.