Clinical trials

Esophageal cancer (EC) ranks among the leading malignant gastrointestinal tumors globally in terms of both incidence and mortality. Cases of EC in China account for over 50% of the global total, with squamous cell carcinoma being the primary pathological type. Locally advanced EC (LAEC), particularly cases where radical surgical resection is not feasible, exhibits high recurrence rates and low 5-year survival rates. However, studies have shown that patients with LAEC who undergo comprehensive treatment followed by surgery experience significantly prolonged survival and improved quality of life compared to those who do not receive surgical intervention. Current conversion treatment regimens under investigation include: chemotherapy alone, chemoradiotherapy, immunotherapy combined with chemotherapy, and immunotherapy combined with chemoradiotherapy-each of these approaches has distinct advantages and limitations. Immunochemotherapy has emerged as a current research focus: it not only demonstrates significantly superior efficacy compared to chemotherapy alone but also exhibits lower cumulative toxicity than radiotherapy-combined conversion regimens, resulting in a more favorable overall benefit-risk ratio. As such, it represents the most promising conversion treatment strategy. Retrospective and prospective clinical studies have shown that low-dose radiotherapy targeting the small intestine can enhance the anti-tumor response of immune checkpoint inhibitors (ICIs) in patients with advanced solid tumor, prolong their overall survival, and increase the incidence of the abscopal effect. Further mechanistic investigations have revealed that intestinal low-dose radiotherapy (ILDR) may augment the immune cancerous lethality by modulating the gut microbiota and their metabolic profiles. Based on the findings from these preliminary studies, the current research plans to conduct a prospective phase II single-arm clinical trial to investigate the efficacy and safety of ILDR combined with immunochemotherapy as conversion therapy in patients with borderline resectable or unresectable esophageal squamous cell carcinoma (BR/UR ESCC). This research plans to enroll at least 39 evaluable cases or a total of 43 cases in two seperated stages, focusing on patients with thoracic BR/UR ESCC. Patients will receive a single fraction of ILDR with a mean dose of 1 Gy, concurrently with 3 cycles of albumin-bound paclitaxel (260 mg/m² on day 1), cisplatin (75 mg/m² on day 1), and tislelizumab (200 mg on day 1). The efficacy and safety of the treatment will be evaluated throughout the study.

Preclinical and clinical evidence suggests that intestinal low-dose radiotherapy (ILDR) may enhance antitumor immune responses by modulating the gut microenvironment, thereby improving the efficacy of immune checkpoint inhibitors (ICBs) in refractory solid tumors. Based on these findings, the investigators initiate a multicohort phase II clinical trial to evaluate the clinical benefit and safety of ILDR combined with PD-1/PD-L1 monoclonal antibody therapy in patients with metastatic solid tumors resistant to prior ICB treatment. In this study, patients are stratified into three parallel cohorts by tumor type (lung cancer, esophageal cancer, and other solid tumors), with 16 patients per cohort (48 in total, including subjects enrolled from the ILDR-01 study). Eligible participants includes patients with advanced metastatic solid tumors progressing after monotherapy or combination ICB treatment, meeting criteria of ECOG performance status 0-2, life expectancy ≥3 months, and have at least one measurable lesion. Exclusion criteria encompasses prior pelvic radiotherapy, ongoing infections, major organ dysfunction, or concurrent antitumor therapies. The primary endpoints includes objective response rate (ORR), disease control rate (DCR), progression-free survival after ILDR (PFS2), and the incidence of abscopal effects. Secondary endpoints includes overall survival (OS), treatment safety, α/β diversity changes in gut microbiota, peripheral blood immune cell subset dynamics, and tumor immune microenvironment remodeling characteristics. All patients receives a 1 Gy jejunoileal radiotherapy followed by PD-1/PD-L1 monoclonal antibody administration (in accordance to prior protocols or guidelines) within 24 hours, with maintenance therapy up to 2 years. Therapeutic efficacy is assessed via RECIST v1.1, while therapeutic toxicity is assessed according to CTCAE v5.0. Paired pre- and post-treatment samples (including wumor tissue, stool, peripheral blood etc.) are collected for metagenomic sequencing, metabolomic analysis, and multi-omics integrative modeling to systematically elucidate the regulation mechanism of gut microbiota-metabolite-immune axis mediated by ILDR. This approach aims to provide theoretical foundations for optimizing treatment strategies in immunotherapy-resistant tumors and identify biomarkers that potentially associated with therapeutic efficacy.

This study aims to explore potential biomarkers for prediction of therapeutic outcomes in patients with solid tumors after radiotherapy