Using MRI and blood markers to tell pseudoprogression from real tumor growth after rectal cancer immunotherapy.

A Study on the Accurate Evaluation of Pseudoprogression of Rectal Cancer Immunotherapy Based on Multitemporal and Multiparameter MRI

This project will test whether combining serial multiparametric rectal MRIs with blood markers and clinical signs can tell pseudoprogression from true progression in people with stage II–IV rectal cancer starting immunotherapy.

Quick facts

• Study type: Observational
• Enrollment: 300 (estimated)
• Sex: All
• Sponsor: Sixth Affiliated Hospital, Sun Yat-sen University (Academic / other)
• Drugs / interventions: immunotherapy
• Locations: 2 sites (Guangzhou, Guangdong and 1 other locations)
• Trial ID: NCT07381322 on ClinicalTrials.gov

What this trial studies

This observational study combines multi‑temporal, multiparametric rectal MRI scans with blood biomarkers (IL-8, NLR, LDH, S100) and clinical indicators (KPS, CEA, T-stage) to distinguish pseudoprogression from true progression following immunotherapy. Imaging and blood tests are collected within two weeks before treatment and again at 6 and 12 weeks after starting PD-1/PD-L1 therapy (with or without CTLA-4 inhibitors), and follow-up CT/MRI or pathology (when available) provide reference standards using iRECIST criteria. Eligible patients are biopsy-confirmed stage II–IV rectal cancer cases chosen by an MDT and who are treatment-naïve prior to immunotherapy. The multicenter project is led from Sun Yat-sen University's Sixth Affiliated Hospital with collaboration from Xinyi People's Hospital and aims to identify signatures that could guide clinical decisions about continuing or changing therapy.

Who should consider this trial

Good fit: Adults with biopsy-confirmed stage II–IV rectal cancer who are treatment-naïve and planned for PD-1/PD-L1 ± CTLA-4 immunotherapy and can undergo baseline and 6‑ and 12‑week multiparametric rectal MRI plus serial blood tests are ideal candidates.

Not a fit: Patients who have had prior anticancer treatment, cannot tolerate MRI or the required follow-up visits, or lack confirmatory pathology when imaging is equivocal may not benefit from this study's findings.

Why it matters

Potential benefit: If successful, this approach could help clinicians distinguish pseudoprogression from true tumor growth so patients avoid stopping effective immunotherapy or undergoing unnecessary surgery.

How similar studies have performed: While imaging and blood biomarkers have been studied for immunotherapy response in other cancers, applying serial multiparametric pelvic MRI combined with these specific blood markers for rectal cancer pseudoprogression is relatively novel.

Eligibility criteria

Inclusion Criteria:

1. Rectal cancer confirmed by biopsy pathology;
2. Clinical stage II-IV determined by imaging examinations;
3. Decided by the MDT team to receive immunotherapy (monotherapy with PD-1/PD-L1 inhibitors or in combination with CTLA-4 inhibitors), without prior treatment of any other kind;
4. Multiparametric MRI images of the rectum obtained within 2 weeks before immunotherapy, and at 6 and 12 weeks after treatment;
5. Follow-up CT/MRI data available; evaluation conducted according to the iRECEST criteria, or surgical resection performed to obtain postoperative pathological results, which are necessary for assessing the efficacy of immunotherapy and diagnosing pseudoprogression versus true progression;
6. Blood test parameters (IL-8, NLR, LDH, S100) and clinical indicators (KPS score, CEA level, T-stage) measured within 2 weeks before immunotherapy, and at 6 and 12 weeks after treatment;
7. In cases where imaging suggests disease progression, pathological biopsy or surgical pathology results must be available.
8. The overall survival period is more than 3 months, and the patient does not have any other uncontrollable diseases;
9. The patient has been fully informed and has signed the informed consent form.

Exclusion Criteria:

1. The primary tumor lesion has been surgically removed at the time of initial diagnosis;
2. History of other malignant tumors;
3. Unable to sign informed consent or complete the trial due to physical or psychological illness;
4. Pregnant or lactating women;
5. Those who are allergic to gadolinium-containing contrast agents or contraindicated to undergo enhanced MRI examination, or those who are claustrophobic or have other contraindications to MRI examination and cannot undergo MRI examination;
6. History of autoimmune diseases such as inflammatory bowel disease;
7. Treatment interruption due to serious complications related to immunotherapy.

Where this trial is running

Guangzhou, Guangdong and 1 other locations

• Sixth affiliated hospital, Sun Yat-sen University — Guangzhou, Guangdong, China (Not_yet_recruiting)
• Xinyi People's hospital — Maoming, Guangdong, China (Recruiting)

Study contacts

• Study coordinator: Peiyi Xie

Conditions Rectal Cancer