A Prospective Phase II Study of Systemic Therapy With Immunotherapy Combined With Personalized Ultrafractionated Stereotactic Adaptive Radiation Therapy (PULSAR) in Unresectable Locally Advanced Gastric Cancer

What this Trial Is About

Researchers are evaluating the combination of first-line systemic therapy plus immunotherapy together with personalized ultrafractionated stereotactic adaptive radiation therapy (PULSAR) in patients with unresectable locally advanced gastric cancer. The study focuses on patients with HER-2 negative, EBV negative, and microsatellite stable (MSS) tumors who have not shown disease progression after at least three cycles of first-line immunotherapy-containing systemic treatment. This phase II prospective study aims to assess whether this combined approach can improve local tumor control, increase chances of surgery, and lengthen progression-free survival. Participants who have completed three or more cycles of first-line immunotherapy-containing systemic therapy without disease progression will receive PULSAR radiation therapy. This involves delivering 6 Gy of radiation per fraction, administered every 3 to 4 weeks, for up to three cycles, alongside their ongoing systemic therapy. The long interval between radiation doses allows normal tissues to recover and offers the chance to adapt the radiation plan before each fraction to reduce gastrointestinal side effects while maximizing tumor targeting. During the study, patients will be monitored for progression-free survival at 12 months following the first PULSAR radiation dose. Assessments will include clinical evaluations and imaging to measure tumor response and safety. Participants must provide written informed consent and meet eligibility criteria related to tumor characteristics and health status. The study is conducted at a single center and sponsored by Samsung Medical Center, with planned follow-up extending until April 2030.

PULSAR Combined With Immunotherapy for Unresectable Locally Advanced Gastric Cancer