CLINICAL TRIAL article
Front. Nutr.
Sec. Nutrition and Microbes
Volume 12 - 2025 | doi: 10.3389/fnut.2025.1626169
A phase II clinical trial of Bifidobacterium longum subsp. longum BL21 for preventing acute radiation enteritis among pelvic radiotherapy patients
Provisionally accepted
- 1Department of Radiotherapy and Oncology, Suzhou, China
- 2The Second Affiliated Hospital of Soochow University, suzhou, China
- 3The Affiliated Wuxi The Affiliated Wuxi People Hospital of Nanjing Medical University,, wuxi, China
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Background: Acute radiation enteritis (ARE) is a common side effect experienced by patients receiving pelvic radiotherapy (RT). Probiotic supplementation is an emerging strategy for preventing ARE. Methods: This phase II trial recruited patients with gynecologic or rectal cancers who received pelvic RT with curative or adjuvant intent. During RT, one packet of Bifidobacterium longum subsp. longum BL21 (BL21) powder was self-administered daily. ARE was assessed and classified according to the Radiation Therapy Oncology Group (RTOG) and Common Terminology Criteria for Adverse Events (CTCAE) toxicity grading criteria. We assessed the safety and efficacy of BL21 to prevent ARE and investigate the changes in the intestinal microbiota. Results: This study enrolled 52 patients, 8 participants withdrew, and 44 patients being included in the final analysis. The safety profile of BL21 during RT was favorable, and we did not observe any serious adverse events associated with BL21. Compared with our historical control data, these patients exhibited lower levels of ≥ grade 2 ARE and required fewer antidiarrheal medications (n=12). Most diarrhea cases were classified as grade 1 (n=22). Analysis of the gut microbiota revealed that the severity of ARE correlates with the abundance of BL21 and the increase in BL21 was associated with greater alpha diversity, an increase in beneficial bacteria, and a decrease in harmful bacteria. Conclusions: The favorable safety profile, exploratory clinical observations of reduced ARE severity versus historical controls, and feasible administration support further investigation of Bifidobacterium longum BL21 as a prophylactic candidate for ARE, warranting validation in Phase III randomized controlled trials.
Keywords: pelvic radiotherapy, Acute radiation enteritis, prevention, Bifidobacterium longum subsp. longum BL21, Gut Microbiota
Received: 10 May 2025; Accepted: 29 Sep 2025.
Copyright: © 2025 yang, gu, liu, zou, Xie, Liu, zhao, Cai and Tian. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: yinyin yang, yangyin33@yeah.net
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