A Phase I/II study to evaluate the safety and preliminary efficacy of human umbilical cord-derived mesenchymal stem cell injection for the treatment of chronic radiation proctitis.

Radiation therapy is frequently used to treat pelvic cancers such as anal, cervical, prostate, and rectal cancer. While effective in controlling local tumors, it can also cause collateral damage to the gastrointestinal tract. The rectum is particularly vulnerable to radiation damage due to its fixed position in the pelvis. In the acute phase, radiation can lead to proctitis, an inflammatory condition characterized by mucosal ulceration, edema, and loss of microvilli. Patients typically present within three months of radiation therapy with symptoms like diarrhea, urgency, and tenesmus. Chronic radiation proctitis can either follow the acute phase or appear after a symptom-free period, typically 8 to 12 months post-radiation treatment. This chronic condition results from radiation-induced small-vessel injury, causing ischemia, obliterative endarteritis, fibrosis, and neovascularization. Rectal bleeding is a common symptom of chronic radiation proctitis.

Clinical studies have demonstrated that mesenchymal stem cell (MSC) treatment offers significant benefits, including anti-inflammatory, immune modulation, and tissue repair effects. Recent research indicates that intralesional injection of MSC is effective in treating radiation proctitis, reducing pain and bleeding without causing severe adverse events. This suggests that MSC treatment could be a promising option for radiation proctitis.

This is a phase I/II study designed to evaluate the safety and preliminary efficacy of MSC treatment for radiation proctitis. Patients will be followed up for 24 months after treatment.

Inclusion Criteria:

1. Fully understand and sign the informed consent form;
2. Age ≥18 years and <80 years;
3. Good physical condition (WHO performance status score 0-1);
4. Pathologically diagnosed with pelvic malignant tumors and received radiotherapy;
5. Diagnosed with chronic radiation proctitis after at least 6 months of endoscopic examination following the completion of radiotherapy and ineffective conventional treatment;
6. Screening period LENT-SOMA score ≥1;
7. Subjects and their spouses or partners have no plans for conception from screening to 6 months after the end of the trial, no plans for sperm or egg donation, and agree to use effective non-pharmacological contraceptive measures during the trial.

Exclusion Criteria:

1. Patients with severe liver or kidney dysfunction during the screening period;
2. Patients with severe congestive heart failure or coronary artery disease during the screening period;
3. Patients with allergic constitution or severe systemic immune diseases;
4. Patients with active gastrointestinal bleeding or acute intestinal obstruction during the screening period;
5. Pregnant patients;
6. Patients with rectal stenosis or fistula formation requiring surgical treatment that limits endoscopic therapy;
7. Patients with a screening period LENT-SOMA score of 4;
8. Patients with tumor recurrence or metastasis;
9. Patients currently participating in other clinical trials at the time of screening or who have not been out of another clinical trial for less than 1 month;
10. Other situations deemed unsuitable for inclusion in this study by the investigator.