Main Session
Sep
27
PQA 01 - Gastrointestinal Cancer and Central Nervous System
2032 - Efficacy of Thymosin a1 in Reducing Serious Adverse Events in Patients with Locally Advanced or Metastatic Abdominopelvic Carcinoma Treated with Concurrent Chemoradiotherapy
Presenter(s)
Lining Chen, MD - Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical , Shenzhen, Guangdong
L. N. Chen1, Y. Zhou1, N. Hu1, Y. Tan1, X. Su1, J. Lei1, T. Lei1, W. Zhang1, L. Feng1, Q. Xiao1, and J. Jin1,2; 1Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, 2Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Purpose/Objective(s):
Concurrent chemoradiotherapy (CCRT) is a standard treatment for locally advanced or metastatic abdominopelvic malignancies but is often associated with significant toxicity, including lymphopenia and radiation-induced injury. Thymosin a1 (Ta1), an immunomodulatory agent, may mitigate treatment-related adverse events. This prospective cohort study evaluated the efficacy of Ta1 in reducing serious adverse events (SAEs) in patients receiving CCRT.Materials/Methods:
Eligible patients were aged 18-85 years with locally advanced or metastatic abdominopelvic carcinoma and ECOG performance status 0-1. The study group received Ta1 in combination with CCRT, initiated at the start of radiotherapy and continued until 2 months post-CCRT, it is planned to recruit 40 patients. The Ta1 regimen consisted of three times weekly for the first six weeks, followed by twice weekly for the subsequent six weeks. Radiotherapy was delivered at a total dose of 45.0-60.0 Gy fractions. Systemic therapy, including chemotherapy, targeted therapy and PD-1/PD-L1 inhibitor was administered per clinical guidelines. A historical control gourp of 20 patients with matched baseline characteristics who received CCRT alone was selected for comparison. The primary endpoint was the incidence of SAEs, defined as grade 3-4 lymphopenia or = grade 3 radiation-induced injury per CTCAE v5.0. Secondary endpoints included total lymphocyte count (TLC), neutrophil-to-lymphocyte ratio (NLR) dynamics during and after radiotherapy, and the time to TLC nadir.Results:
Between July 2025 and December 2025, 19 patients were enrolled in the study group (Ta1 plus CCRT), and 20 patients were included in the control group (CCRT alone). Baseline characteristics were well balanced between groups. The incidence of SAEs was significantly lower in the study group compared with the control group (5.3%,?1/19? vs 30%,?6/20?; P=0.044). Although the incidence of grade 3-4 lymphopenia was similar between groups (94.7% vs.90.0%; P=0.579), the median time to TLC nadir was delayed, in the study group (6 weeks; range, 4-10 weeks) versus the control group (5 weeks; range, 3-6 weeks). During radiotherapy, the study group demonstrated a milder and slower increase in NLR compared with controls. Following radiotherapy completion, the study group achieved faster NLR recovery with fewer extreme elevated values.Conclusion:
The addition of Ta1 to CCRT significantly reduced the risk of serious adverse events in patients with locally advanced or metastatic addominopelvic carcinoma. Ta1 was associated with delayed onset of lymphopenia, attenuated NLR elevation during treatment, and accelerated immune recovery post-treatment. These findings provide preliminary clinical evidence supporting the immunoprotective role of Ta1 during CCRT. Further validation in larger cohorts with extended follow-up is warranted.