Short-Course Radiotherapy Followed by CAPOX With or Without Iparomlimab and Tuvonralimab in pMMR/MSS Locally Advanced Rectal Cancer (SCRIT): A Multicenter Phase III Randomized Controlled Trial (SCRIT)

This multicenter, randomized, controlled, phase III trial evaluates whether adding iparomlimab and tuvonralimab injection to CAPOX consolidation chemotherapy after short-course radiotherapy improves tumor response in patients with treatment-naive, proficient mismatch repair/microsatellite-stable (pMMR/MSS) locally advanced rectal adenocarcinoma. Eligible patients will be randomly assigned in a 1:1 ratio to receive short-course radiotherapy followed by CAPOX plus iparomlimab and tuvonralimab, or short-course radiotherapy followed by CAPOX alone.

After total neoadjuvant therapy, patients with a clinical complete response may undergo a Watch-and-Wait strategy, whereas other patients will undergo total mesorectal excision according to standard clinical practice. The primary endpoint is complete response rate, defined as pathologic complete response after surgery or clinical complete response sustained for more than 1 year. Secondary endpoints include 3-year relapse-free survival, 3-year overall survival, sphincter preservation rate, and grade 3-4 acute adverse events. Exploratory analyses will assess tissue and blood biomarkers associated with treatment response.

Study Overview

• Status: Not yet recruiting
• Conditions: Radiotherapy; Immunotherapy; Local Advanced Rectal Cancer
• Intervention / Treatment: Radiation: Short-Course Radiotherapy; Drug: Consolidation treatment (With ICIs); Drug: Consolidation treatment (Without ICIs)

• Study Type: Interventional
• Enrollment (Estimated): 180
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Jinbo Yue Doctor; Phone Number: 0531-67626442; Email: jbyue@sdfmu.edu.cn

Study Locations

• China
  • Shandong
    • Jinan, Shandong, China, 0531
      • Shandong Cancer Hospital and Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients aged 18-75 years with histologically confirmed pMMR/MSS rectal adenocarcinoma are eligible if they have MRI-defined clinical stage II or III disease according to AJCC 8th edition, tumor located within 12 cm from the anal verge, and at least one high-risk feature, including cT4b, cN2, EMVI positivity, MRF positivity, lateral lymph node positivity, tumor deposits, or tumor located ≤5 cm from the anal verge. Patients must have no distant metastasis, ECOG performance status 0-1, life expectancy greater than 6 months, and adequate hematologic, hepatic, and renal function

Exclusion Criteria:

• active or prior autoimmune disease requiring systemic treatment, use of immunosuppressive therapy or systemic corticosteroids at immunosuppressive doses, severe hypersensitivity to monoclonal antibodies, uncontrolled cardiac disease, significant coagulopathy or bleeding tendency, active infection, interstitial lung disease or severe pulmonary dysfunction, HIV infection or active hepatitis, prior or concurrent malignancy except specified cured cancers, recent investigational drug use, planned use of other systemic antitumor therapy during the study, pregnancy or breastfeeding, and any other condition judged by the investigator to make participation unsuitable.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Treatment; Short-Course Radiotherapy + CAPOX + Iparomlimab and Tuvonralimab Radiotherapy: Short-course external-beam radiotherapy will be delivered to the rectal primary tumor and corresponding lymphatic drainage regions using IMRT or VMAT. The prescribed dose is 25 Gy in 5 fractions over 1 week. No concurrent chemotherapy will be administered during short-course radiotherapy. Consolidation treatment: Iparomlimab and tuvonralimab injection will be administered at 5 mg/kg by intravenous infusion every 21 days for 6 cycles. CAPOX chemotherapy will consist of oxaliplatin 130 mg/m² intravenously on day 1 plus capecitabine 1000 mg/m² orally twice daily on days 1-14 of each 21-day cycle, for 6 cycles.	Radiation: Short-Course Radiotherapy; Short-course external-beam radiotherapy will be delivered to the rectal primary tumor and corresponding lymphatic drainage regions using IMRT or VMAT. The prescribed dose is 25 Gy in 5 fractions over 1 week. No concurrent chemotherapy will be administered during short-course radiotherapy.; Drug: Consolidation treatment (With ICIs); Iparomlimab and tuvonralimab injection will be administered at 5 mg/kg by intravenous infusion every 21 days for 6 cycles. CAPOX chemotherapy will consist of oxaliplatin 130 mg/m² intravenously on day 1 plus capecitabine 1000 mg/m² orally twice daily on days 1-14 of each 21-day cycle, for 6 cycles.
Active Comparator: Control; Short-Course Radiotherapy + CAPOX Radiotherapy: Short-course external-beam radiotherapy will be delivered to the rectal primary tumor and corresponding lymphatic drainage regions using IMRT or VMAT. The prescribed dose is 25 Gy in 5 fractions over 1 week. No concurrent chemotherapy will be administered during short-course radiotherapy. Consolidation treatment: CAPOX chemotherapy will consist of oxaliplatin 130 mg/m² intravenously on day 1 plus capecitabine 1000 mg/m² orally twice daily on days 1-14 of each 21-day cycle, for 6 cycles.	Radiation: Short-Course Radiotherapy; Short-course external-beam radiotherapy will be delivered to the rectal primary tumor and corresponding lymphatic drainage regions using IMRT or VMAT. The prescribed dose is 25 Gy in 5 fractions over 1 week. No concurrent chemotherapy will be administered during short-course radiotherapy.; Drug: Consolidation treatment (Without ICIs); CAPOX chemotherapy will consist of oxaliplatin 130 mg/m² intravenously on day 1 plus capecitabine 1000 mg/m² orally twice daily on days 1-14 of each 21-day cycle, for 6 cycles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Complete Response (CR) Rate	Complete response rate is defined as the proportion of patients who achieve either pathologic complete response (pCR) after surgery or sustained clinical complete response (cCR) for more than 1 year during Watch-and-Wait follow-up.	From randomization to completion of definitive response assessment, including surgical pathological assessment after total neoadjuvant therapy or confirmation of sustained clinical complete response after at least 12 months of Watch-and-Wait follow-up

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
3-Year Relapse-Free Survival (RFS)	Relapse-free survival is defined as the time from randomization to the first evidence of disease relapse or recurrence. Patients without relapse/recurrence or death will be censored at the date of last disease assessment.	From randomization to the first documented disease relapse/recurrence, death from any cause, or 3 years after randomization, whichever occurs first.
3-Year Overall Survival (OS)	Overall survival is defined as the time from randomization to death from any cause. Patients who are alive at the time of analysis will be censored at the date of last known survival follow-up.	From randomization to death from any cause or 3 years after randomization, whichever occurs first.
Sphincter Preservation Rate	Sphincter preservation rate is defined as the proportion of patients who successfully preserve anal sphincter structure and function and avoid permanent colostomy.	From randomization to completion of definitive surgery, or to at least 12 months after initiation of Watch-and-Wait follow-up for patients who do not undergo surgery; approximately up to 18-24 months after randomization.
Incidence of Grade 3-4 Acute Adverse Events	Acute adverse events will be graded and recorded according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. The incidence of grade 3-4 acute adverse events will be summarized by treatment arm.	From the start of study treatment to 30 days after completion of neoadjuvant treatment.

Collaborators and Investigators

• Sponsor: Shandong Cancer Hospital and Institute
• Investigators: Principal Investigator: Jinbo Yue, Doctor, Study Principal Investigator

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): July 15, 2029
• Study Completion (Estimated): July 15, 2030

Study Registration Dates

• First Submitted: June 30, 2026
• First Submitted That Met QC Criteria: June 30, 2026
• First Posted (Actual): July 7, 2026

Study Record Updates

• Last Update Posted (Actual): July 7, 2026
• Last Update Submitted That Met QC Criteria: June 30, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: immunotherapy; radiotherapy; local advanced rectal cancer
• Other Study ID Numbers: SDZLEC2026-051-002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No