Actively Recruiting
Low-Dose Radiotherapy to Sensitize Pucotenlimab Plus CAPEOX for pMMR Locally Advanced Rectal Cancer
Led by Sun Yat-sen University · Updated on 2026-05-07
50
Participants Needed
1
Research Sites
337 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
This is a prospective, open-label, randomized, parallel-group phase II trial evaluating the efficacy and safety of a low-dose radiotherapy sensitization strategy combined with a PD-1 antibody (pucotenlimab) and CAPEOX as neoadjuvant therapy in patients with pMMR/MSS locally advanced rectal adenocarcinoma. Participants will be randomized 1:1 to receive either 2 Gy or 5 Gy low-dose radiotherapy. Low-dose radiotherapy is delivered as a single fraction of 2 Gy (Arm A) or 5 Gy (Arm B). On the day after radiotherapy, participants will start pucotenlimab 200 mg IV Q3W (administered on Day 2 of each 21-day cycle) plus CAPEOX chemotherapy. Early response will be assessed after 2 cycles using endoscopy and pelvic MRI to guide subsequent treatment: participants with partial response may discontinue radiotherapy and continue neoadjuvant systemic therapy; participants with stable disease may switch to standard chemoradiotherapy; participants with progressive disease will receive multidisciplinary-team-guided salvage therapy. After 4 cycles, participants with clinical complete response may adopt a watch-and-wait strategy; otherwise, they will undergo radical surgery 2-4 weeks after completion of neoadjuvant therapy. Long-term follow-up will include recurrence and survival outcomes and quality of life.
CONDITIONS
Official Title
Low-Dose Radiotherapy to Sensitize Pucotenlimab Plus CAPEOX for pMMR Locally Advanced Rectal Cancer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Provided written informed consent before study procedures
- Aged between 18 and 75 years at enrollment
- Histologically confirmed rectal adenocarcinoma
- Tumor located within 10 cm from the anal verge by endoscopy or imaging
- Locally advanced cancer defined as clinical stage T2N+ or T3-T4a based on pelvic MRI
- Proficient mismatch repair (pMMR) or microsatellite-stable (MSS) status confirmed by testing
- No evidence of distant metastasis on chest, abdominal, and pelvic CT scans
- Circumferential resection margin of 2 mm or more without involvement of mesorectal fascia on baseline MRI
- Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
- Adequate organ function including neutrophil count ≥1.5 × 10⁹/L, platelet count ≥100 × 10⁹/L, hemoglobin ≥90 g/L
- Total bilirubin ≤1.5 times upper limit of normal (ULN)
- AST and ALT ≤2.5 times ULN
- Creatinine clearance ≥50 mL/min
- Thyroid-stimulating hormone within normal limits
- Women of childbearing potential must have a negative pregnancy test and agree to use effective contraception during and after the study
- Men with partners of childbearing potential must agree to use effective contraception during and after the study
You will not qualify if you...
- Clinical T4b disease with tumor invading adjacent organs or structures on imaging
- Circumferential resection margin less than 2 mm or involvement of mesorectal fascia on baseline MRI
- Evidence of distant metastasis outside the pelvis
- Prior pelvic or abdominal radiotherapy
- Prior treatment with immune checkpoint inhibitors or systemic anticancer therapy for rectal cancer
- Active or past autoimmune disease requiring systemic treatment except low-risk conditions like vitiligo or resolved childhood asthma
- Use of systemic immunosuppressive therapy above prednisone 10 mg/day within 2 weeks before enrollment
- Known HIV infection
- Active hepatitis B or C virus infection requiring treatment
- Uncontrolled active infection or serious medical condition compromising safety or compliance
- History of another malignancy within 5 years except certain low-risk skin or cervical cancers
- Known allergy or hypersensitivity to pucotenlimab, oxaliplatin, capecitabine, or their components
- Pregnant or breastfeeding women
- Any condition making participation unsuitable as judged by the investigator
AI-Screening
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Trial Site Locations
Total: 1 location
1
Dept. of Colorectal Surgery, Sun Yat-sen University Cancer Center. Yuexiu District, Dongfeng East Road 651
Guangzhou, Guanggong, China, 510060
Actively Recruiting
Research Team
W
Wu Jiang
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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