Safety and Efficacy of NOM and OPFS Versus RO for dMMR/MSI-H or POLE-Mutated Gastrointestinal Cancers (NOR-MP)

Safety and Efficacy of Nonoperative Management (NOM) and Organ Preservation First Strategy (OPFS) Versus Radical Operation (RO) for dMMR/MSI-H or POLE-Mutated Gastrointestinal Cancers: A Single-Center, Bidirectional Registry Study

Purpose:

The purpose of this study is to evaluate the safety and efficacy of Non-Operative Management (NOM) and Organ Preservation First Strategy (OPFS) compared with Radical Operation (RO) in patients with deficient mismatch repair/microsatellite instability-high (dMMR/MSI-H) or POLE-mutated gastrointestinal cancers.

Background & Design:

With the remarkable efficacy of neoadjuvant immunotherapy in dMMR/MSI-H or POLE-mutated gastrointestinal tumors, organ preservation has become a promising alternative to highly invasive surgeries. The NOR-MP trial is a single-center, bidirectional registry study consisting of two parts: a retrospective cohort study and a prospective observational registry.

Intervention Group (NOM/OPFS): Patients who achieve a clinical complete response (cCR) or near-cCR after neoadjuvant immunotherapy will undergo a "Watch & Wait" (W&W) strategy. Patients with near-cCR or non-cCR who are eligible for organ preservation will undergo local excision (LE) or endoscopic resection (including ESD or EMR).

Comparison Group (Radical Operation): Patients who undergo standard radical surgical resection after neoadjuvant immunotherapy.

The study aims to determine whether an organ-preserving approach can achieve comparable oncological outcomes and safety profiles while significantly improving patients' quality of life compared to radical surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Gastrointestinal Cancers; Gastrointestinal Cancers - Stomach; Gastrointestinal Cancers - Colorectal; Gastrointestinal Cancers - Anus
• Intervention / Treatment: Other: NOM/OPFS

Detailed Description

The NOR-MP trial is a single-center, bidirectional registry study designed to compare the clinical outcomes of Organ Preservation First Strategy (OPFS) / Non-Operative Management (NOM) against standard Radical Operation (RO) for patients diagnosed with dMMR/MSI-H or POLE-mutated gastrointestinal cancers. The study is divided into two sequential parts based on the nature of data collection:

Part 1: Retrospective Cohort Study

This part retrospectively reviews the medical records of eligible patients with dMMR/MSI-H or POLE-mutated gastrointestinal cancers who previously completed neoadjuvant immunotherapy. Patients are allocated into two historical cohorts:

Experimental Cohort (NOM/OPFS): Patients who achieved cCR/near-cCR after neoadjuvant immunotherapy and entered the "Watch & Wait" (W&W) program, as well as those with near-cCR or non-cCR who underwent local excision (LE) or endoscopic resection (including Endoscopic Submucosal Dissection [ESD] or Endoscopic Mucosal Resection [EMR]).

Control Cohort (RO): Patients who underwent radical surgical operation after neoadjuvant immunotherapy. Pathological outcomes (including the proportions of ypCR, ypTisN0, and ypT1-2N0) and surgical safety data will be collected and analyzed.

Part 2: Prospective Registry Study

This part prospectively enrolls newly diagnosed patients with dMMR/MSI-H or POLE-mutated gastrointestinal cancers receiving neoadjuvant immunotherapy. Following treatment evaluation by the multi-disciplinary NOR-MP research team, patients are enrolled into two parallel observational tracks:

Experimental Cohort (NOM/OPFS): Patients eligible for and consenting to NOM or OPFS. This includes the W&W strategy for those achieving cCR/near-cCR, and LE or endoscopic resection (ESD/EMR) for those with near-cCR or non-cCR.

Control Cohort (RO): Patients who proceed to standard radical operation. Pathological response distribution (proportions of ypCR, ypTisN0, ypT1-2N0, and ypT3+ diseases) and short-to-long-term surgical safety endpoints will be prospectively documented.

By comparing the retrospective and prospective cohorts, this study evaluates whether the omission of radical surgery is oncologically safe and preserves organ function without compromising long-term survival.

• Study Type: Observational
• Enrollment (Estimated): 22

Contacts and Locations

• Study Contact: Name: Xiaokang Lei, M.D.; Phone Number: +8618811181993; Email: lxkpku@163.com

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

The target population consists of adult patients diagnosed with primary gastrointestinal cancers (including but not limited to colorectal cancer, gastric cancer, and gastroesophageal junction cancer) that are histologically confirmed as deficient mismatch repair/microsatellite instability-high (dMMR/MSI-H) or harboring polymerase epsilon (POLE) exonuclease domain mutations. All enrolled patients must have received or are scheduled to receive neoadjuvant or conversion immunotherapy prior to definitive local tumor management strategy determination.

Description

Inclusion Criteria:

• Histologically confirmed primary gastrointestinal adenocarcinoma or squamous cell carcinoma (e.g., colorectal cancer, gastric cancer, gastroesophageal junction cancer).
• Confirmed as deficient mismatch repair (dMMR) by immunohistochemistry (IHC), high microsatellite instability (MSI-H) by polymerase chain reaction (PCR) or next-generation sequencing (NGS), or harboring POLE exonuclease domain mutations.
• Received neoadjuvant/conversion immunotherapy (immune checkpoint inhibitors, either monotherapy or combination therapy) prior to treatment response evaluation.
• For the Retrospective Cohort (Part 1): Patients treated between [Start Month/Year] and [End Month/Year] who completed evaluation and subsequent strategy (NOM/OPFS or RO).
• For the Prospective Cohort (Part 2): Newly diagnosed patients who consent to long-term follow-up and multi-disciplinary team (MDT) assessment for organ preservation or radical surgery.
• Age ≥ 18 years at the time of diagnosis.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

Exclusion Criteria:

• Concurrently diagnosed with other active malignant tumors within the past 5 years.
• Patients with proficient mismatch repair (pMMR) / microsatellite stable (MSS) tumors, or wild-type POLE status.
• Evidence of untreatable distant metastasis or systemic disease that precludes local tumor management (NOM/OPFS or radical operation).
• Inability to undergo regular endoscopic, radiological (MRI/CT), or clinical follow-up due to compliance or geographic reasons.
• Refusal to sign the informed consent form (applicable to the prospective cohort).

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Experimental Cohort (NOM/OPFS); Retrospective Cohort Study: Patients who achieved cCR/near-cCR after neoadjuvant immunotherapy and entered the "Watch & Wait" (W&W) program, as well as those with near-cCR or non-cCR who underwent local excision (LE) or endoscopic resection (including Endoscopic Submucosal Dissection [ESD] or Endoscopic Mucosal Resection [EMR]). Prospective Registry Study: Patients eligible for and consenting to NOM or OPFS. This includes the W&W strategy for those achieving cCR/near-cCR, and LE or endoscopic resection (ESD/EMR) for those with near-cCR or non-cCR.	Other: NOM/OPFS; Patients eligible for and consenting to NOM or OPFS. This includes the W&W strategy for those achieving cCR/near-cCR, and LE or endoscopic resection (ESD/EMR) for those with near-cCR or non-cCR.
Control Cohort (RO); Retrospective Cohort Study: Patients who underwent radical surgical operation after neoadjuvant immunotherapy. Pathological outcomes (including the proportions of ypCR, ypTisN0, and ypT1-2N0) and surgical safety data will be collected and analyzed. Prospective Registry Study: Patients who proceed to standard radical operation. Pathological response distribution (proportions of ypCR, ypTisN0, ypT1-2N0, and ypT3+ diseases) and short-to-long-term surgical safety endpoints will be prospectively documented.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Organ Preservation Rate (for OPFS/NOM group)	The percentage of patients in the NOM/OPFS group who successfully maintain their native organ without requiring radical surgical resection or permanent stoma.	Up to 3 years after the completion of neoadjuvant immunotherapy.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Surgical Safety and Postoperative Complications	Incidence and severity of perioperative complications classified by the Clavien-Dindo classification. This compares the safety data among patients undergoing Radical Operation (RO), Local Excision (LE), or endoscopic resection (ESD/EMR).	Within 30 days and 90 days post-surgery.
Pathological Response Distribution (for RO group)	Proportions of patients in the radical operation cohort achieving pathological complete response (ypCR), ypTisN0, ypT1-2N0, and ypT3+ diseases to characterize the pathological efficacy of neoadjuvant immunotherapy.	At the time of radical surgery (typically within 4-12 weeks post-immunotherapy).
Local Regrowth / Recurrence Rate	Rate of tumor regrowth in patients undergoing the "Watch & Wait" strategy, or local recurrence in patients undergoing local/endoscopic excision.	Followed up at regular intervals (every 3-6 months) up to 3 years.
Overall Survival (OS)	Defined as the time from treatment initiation to death from any cause.	Up to 5 years.
Disease-Free Survival (DFS) / Disease-Specific Survival (DSS)	To compare the long-term oncological efficacy between the NOM/OPFS group and the RO group. DFS is defined as the time from the start of neoadjuvant immunotherapy to the date of first documentation of disease recurrence (local, regional, or distant), progression, or death from any cause.	From enrollment/treatment initiation up to 5 years.

Collaborators and Investigators

• Sponsor: Peking University Cancer Hospital & Institute

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): January 15, 2027
• Study Completion (Estimated): January 15, 2030

Study Registration Dates

• First Submitted: June 6, 2026
• First Submitted That Met QC Criteria: June 6, 2026
• First Posted (Actual): June 11, 2026

Study Record Updates

• Last Update Posted (Actual): June 11, 2026
• Last Update Submitted That Met QC Criteria: June 6, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Colorectal cancer; Gastric cancer; Gastrointestinal cancers
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Intestinal Diseases; Digestive System Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Stomach Diseases; Intestinal Neoplasms; Rectal Diseases; Colonic Diseases; Stomach Neoplasms; Colorectal Neoplasms; Gastrointestinal Neoplasms
• Other Study ID Numbers: PKUCH-NORMP trial

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