Watch and Wait in PD-1 Monoclonal Antibody Treated dMMR/MSI-H Distal Rectal Cancer (BASKET)

April 23, 2026 updated by: Sixth Affiliated Hospital, Sun Yat-sen University

Watch and Wait in Patients With dMMR/MSI-H Distal Rectal Cancer Accessed Pathological Complete Response After PD-1 Monoclonal Antibody Therapy-an Open Label, Multicenter, Prospective Study (BASKET)

Immunotherapy has achieved significant therapeutic effect in DNA mismatch repair-deficient or microsatellite instability-high (dMMR/MSI-H) colorectal cancer (CRC) , more than fifty percent of dMMR/MSI-H CRC patients might get pathological complete response(pCR) after PD-1 monoclonal antibody treatment. For distant rectal cancer(RC), radical resection and neoadjuvant chemotherapy or chemoradiotherapy might cause lots of treatment cost,damage to defecation and sexual function, acute toxicity, chronic dysfunction, even loss of anus and psychological disorder. This study aims to evaluate the effect and safety of watch and wait in patients with dMMR/MSI-H distal RC accessed pCR after PD-1 monoclonal antibody therapy.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Immunotherapy has achieved significant therapeutic effect in DNA mismatch repair-deficient or microsatellite instability-high (dMMR/MSI-H) colorectal cancer (CRC). MMR expression and MSS status are the important effective factors of immunotherapy. PD-1monocolnal antibody therapy has accessed excellent treatment effect in advanced dMMR/MSI-H CRC and neoadjuvant therapeutic effect in early colon cancer, more than fifty percent of dMMR/MSI-H CRC patients might get pathological complete response(pCR) after PD-1 monoclonal antibody treatment. The treatments had been proved to be safe and the toxicities were controllable. Rectal cancer(RC) is one of the most common malignant tumors in China. So far, radical resection with or without neoadjuvant chemotherapy of chemoradiotherapy are still standard comprehensive treatments recommended to distal RC by NCCN, ESMO and CSCO. For distant RC, radical resection and neoadjuvant chemotherapy or chemoradiotherapy might cause lots of treatment cost,damage to defecation and sexual function, acute toxicity, chronic dysfunction, even loss of anus and psychological disorder. So far, whether watch and wait could be performed in patients with dMMR/MSI-H distal RC accessed pCR after PD-1 monoclonal antibody therapy or not is still not clear. Thus, this study aims to evaluate the effect and safety of watch and wait in patients with dMMR/MSI-H distal RC accessed pCR after PD-1 monoclonal antibody therapy.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
47

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • China
    • Guangdong
      • Guangzhou, Guangdong, China

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 80 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

Preliminary inclusion criteria：

  • Histological identified rectal adenocarcinoma,
  • Tumor biopsy immunohistochemical (IHC) identified dMMR, including one or more deficient of the MSH1,MSH2,MSH6 and PMS2 protein expression and diagnosed as deficient mismatch repair(dMMR), or next generation sequencing identified (MSI-H)； MRI identified tumor inferior margin lower than peritoneal reflection,
  • Clinical staging TxNxM0, with or without positive MRF, with or without positive EMVI,
  • Staging method：all patients undergo rectal palpation, high resolution MRI ± transrectal Ultrasound examination，positive perienteric lymph node(LN): short diameter ≥10mm LN or LN with typical metastatic shape and MRI character, clinical data should be re-evaluated and judged by center evaluation group when there are contradictory stagings，distant metastasis were excluded by chest and abdominal enhanced CT and pelvic enhanced MRI,
  • No intestinal obstruction symptom，or obstruction relieved after proximal colostomy,
  • No rectal surgery history,
  • No chemotherapy or radiotherapy history,
  • No biopharmaceutical treatment history(such as monoclonal antibody), immunotherapy(such as anti PD-1antibody, anti PD-L1 antibody, anti PD-L2 antibody or anti CTLA-4), or other research drug treatment,
  • Endocrinotherapy history restriction:No
  • Informed consent assigned, Final inclusion criteria：
  • Clinical complete response (cCR)(Chest,abdominal and pelvic enhanced CT or pelvic enhanced MRI or transrectal ultrasound proved)
  • Transrectal ultrasound biopsy or endoscopic biopsy proved pathologically complete response (pCR)

Exclusion Criteria:

  • Arrhythmia need anti-arrhythmia treatment(except β-blocking agent or Digoxin)，symptomatic coronary heart disease or myocardial ischemia(myocardial infarction within 6 months) or congestive heart-failure (CHF) > NYHA grade II,
  • Severe hypertension not well controlled by drugs,
  • HIV infection history or active phase of chronic Hepatitis B or C(high copies of virus DNA),
  • Active tuberculosis(TB)，accepting anti-TB treatment or anti-TB treatment within 1 year before trial screen,
  • Other active clinical severe infection(NCI-CTC V5.0),
  • Outside pelvic distant metastasis evidences,
  • Dyscrasia, organ dysfunction,
  • Pelvic or abdominal radiotherapy history,
  • Multiple CRC or Multi-primary tumors；
  • Epilepsy need treatments(Steroid or anti-epilepsy therapy),
  • Other malignant tumor history within 5 years,
  • Over abuse of drugs, medical and psychological or social conditions that might interfere patients or evaluation of the study results,
  • Any active autoimmune disease or autoimmune disease history (including but not restricted：interstitial pneumonia, uveitis,enteritis, hepatitis,hypophysitis, nephritis, hyperthyroidism, hypothyroidism, asthma need bronchodilators),
  • Any anti-infection vaccine injection 4 weeks before inclusion ,
  • Long-term exposure to immune-suppressor, combination of systemic or topical use of corticosteroids (dose>10mg/day prednisolone or equivalent hormone)；
  • Known or suspicious allergy to any study related drugs,
  • Any unstable state might cause damage to the safety and compliance of patients,
  • Pregnant or breast feeding women who has ability to have children while without contraception,
  • Refuse to sign informed consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: watch and wait
patients with DNA mismatch repair-deficient or microsatellite instability-high distal rectal cancer accessed pathological complete response after 6 courses of PD-1 monoclonal antibody (200mg/Course/Q3W) therapy and start watch and wait.
Behavioral: watch and wait
patients with DNA mismatch repair-deficient or microsatellite instability-high distal rectal cancer accessed pathological complete response after 6 courses of PD-1 monoclonal antibody (200mg/Course/Q3w) therapy and start watch and wait.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
1 year DFS rate
Time Frame: 1 year
1 year Disease Free Survival Rate
1 year

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Incidence rate of Grade ≥3 PD-1monoclonal antibody-related adverse events
Time Frame: 1 year
Incidence rate of participants with Grade ≥3 PD-1monoclonal antibody-related adverse events as assessed by CTCAE v4.0
1 year
local recurrent rate
Time Frame: 3 years
local recurrent rate of original rectal cancer
3 years
distant metastasis rate
Time Frame: 3 years
distant metastasis rate
3 years
3 years DFS Rate
Time Frame: 3 years
3 years Disease Free Survival Rate
3 years
3 years OS rate
Time Frame: 3 years
3 years Overall Survival Rate
3 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Sixth Affiliated Hospital, Sun Yat-sen University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Chair: Jianping Wang, MD, Sixth Affiliated Hospital, Sun Yat-sen University
  • Study Chair: Jun Huang, MD, Sixth Affiliated Hospital, Sun Yat-sen University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 1, 2021

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 19, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 20, 2020

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 24, 2020

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 27, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • E2020132

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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