Phase Ib/II Trial of Serine/Glycine-Restricted Diet With Chemoradiotherapy for Rectal Cancer (SG-RCT)

October 27, 2026 updated by: Xuelei Ma MD

Phase Ib/II Clinical Trial of Serine/Glycine-Restricted Diet Combined With Chemoradiotherapy for Neoadjuvant Treatment of Rectal Cancer

This is a Phase Ib/II seamless, open-label, clinical trial evaluating the safety and efficacy of a serine/glycine-restricted diet combined with neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer (LARC).

The study consists of two phases. Phase Ib is a non-randomized, single-arm safety run-in phase enrolling 6 patients, all of whom will receive the experimental regimen (a serine/glycine-restricted diet plus CAPOX chemotherapy and long-course radiotherapy). The primary objective of Phase Ib is to assess the safety, tolerability, and dietary compliance.

If the safety criteria are met in Phase Ib (≥3 grade diet-related adverse event rate ≤20% and compliance rate ≥70%), the study will proceed to Phase II. Phase II is a randomized, open-label, parallel-controlled phase in which 120 additional patients will be randomized in a 1:1 ratio to either the experimental group (serine/glycine-restricted diet plus standard neoadjuvant chemoradiotherapy) or the control group (standard neoadjuvant chemoradiotherapy alone). The total enrollment is 126 patients (6 in Phase Ib + 120 in Phase II).

The primary endpoint is the complete response rate (pCR + cCR). Secondary endpoints include major pathological response (MPR) rate, R0 resection rate, mrTRG regression grade, event-free survival (EFS), progression-free survival (PFS), overall survival (OS), adverse event profile, changes in serum amino acid levels, quality of life (EORTC QLQ-C30), and nutritional status. Exploratory endpoints include gut microbiome diversity and tumor immune microenvironment changes.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet 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.

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.
126

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.
  • Phase 2
  • Phase 1

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.

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

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Written informed consent obtained prior to any study-related procedures.
  • Male or female, aged 18-80 years.
  • Histologically confirmed locally advanced mid-to-upper rectal cancer, staged as cT3, cT4, or node-positive by pelvic MRI.
  • ECOG performance status score of 0 or 1.
  • NRS-2002 score < 3.
  • BMI ≥ 18.5 kg/m².
  • Capable of oral intake or via feeding tube, and able to tolerate enteral nutrition.
  • Adequate organ function meeting the following laboratory criteria:

ANC ≥ 1.5×10⁹/L (without G-CSF within 14 days);

Platelet count ≥ 100×10⁹/L;

Hemoglobin ≥ 9 g/dL (without transfusion or erythropoietin within 7 days);

Serum albumin ≥ 3.0 g/dL;

Total bilirubin ≤ 1.5× ULN;

AST and ALT ≤ 2.5× ULN;

Creatinine clearance ≥ 50 mL/min or serum creatinine ≤ 1.5× ULN;

INR ≤ 1.5× ULN, PT and APTT ≤ 1.5× ULN;

Urine protein < 2+;

Cardiac enzymes within normal range.

  • Female patients of childbearing potential must have a negative serum pregnancy test within 3 days prior to study treatment and agree to use highly effective contraception for at least 6 months after the last dose.
  • All patients at risk of pregnancy must use highly effective contraceptive methods during the treatment period and up to 120 days (or 180 days after last chemotherapy dose) after the last dose of study treatment.

Exclusion Criteria:

  • Stage I or Stage IV rectal cancer.
  • Cognitive impairment or psychiatric disorders preventing comprehension of the study content.
  • Central nervous system or meningeal metastases.
  • Clinically symptomatic moderate to severe ascites requiring therapeutic paracentesis.
  • Uncontrolled or moderate to severe pleural effusion and pericardial effusion.
  • Severe diarrhea, intractable vomiting, severe malabsorption syndrome, paralytic or mechanical intestinal obstruction; tracheoesophageal fistula, gastrointestinal perforation or fistula, intra-abdominal abscess; gastrointestinal bleeding (CTCAE grade ≥ 3 within 6 months or grade ≥ 2 within 3 months before study treatment).
  • Any other condition that may affect the study results or lead to forced discontinuation as judged by the investigator (e.g., alcohol or drug abuse, serious concurrent diseases, severe laboratory abnormalities).
  • Known allergy to the study drugs or nutritional powder active ingredients or excipients.
  • Poorly controlled diabetes mellitus.
  • Severe cardiovascular/cerebrovascular diseases, including CVA, TIA, myocardial infarction, major vascular disease within 6 months; uncontrolled symptomatic cardiac disease (e.g., unstable angina, NYHA class II or higher heart failure, LVEF < 50% on echocardiography, or severe uncontrolled arrhythmia).
  • Pregnant or lactating women.
  • Any other condition that the investigator considers unsuitable for enrollment.

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: Randomized
  • Interventional Model: Parallel 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: Serine/Glycine-Restricted Diet Plus Chemoradiotherapy
Dietary supplement: Serine/Glycine-Restricted Diet

A specialized liquid nutritional powder free of serine and glycine, supplemented with a specified list of low-serine/glycine foods. Patients receive 30 kcal/kg/day energy and 1.5 g/kg/day protein for 7-8 weeks during the neoadjuvant treatment period.

Drug: CAPOX Chemotherapy

Oxaliplatin and capecitabine combination chemotherapy administered for 6 cycles as part of the standard neoadjuvant regimen.

Radiation: Long-Course Radiotherapy

Pelvic radiotherapy delivered with a total dose of 45.0-50.4 Gy in 25-28 fractions, concurrent with capecitabine.
Active Comparator: Standard Chemoradiotherapy Without Dietary Restriction
Drug: CAPOX Chemotherapy

Oxaliplatin and capecitabine combination chemotherapy administered for 6 cycles as part of the standard neoadjuvant regimen.

Radiation: Long-Course Radiotherapy

Pelvic radiotherapy delivered with a total dose of 45.0-50.4 Gy in 25-28 fractions, concurrent with capecitabine.

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
Rate of Complete Response (Pathological and Clinical)
Time Frame: At the time of radical surgery (approximately 24 weeks after initiation of neoadjuvant treatment), or at the time of clinical evaluation for cCR (if patients opt for a Watch-and-Wait strategy).

The proportion of patients achieving pathological complete response (pCR) or clinical complete response (cCR). pCR is defined as no residual tumor cells in the resected tumor and regional lymph nodes. cCR is defined as no evidence of residual tumor in the primary lesion and regional lymph nodes after neoadjuvant therapy, assessed by digital rectal examination, endoscopy, pelvic high-resolution MRI (T2WI/DWI), and serum CEA levels.
At the time of radical surgery (approximately 24 weeks after initiation of neoadjuvant treatment), or at the time of clinical evaluation for cCR (if patients opt for a Watch-and-Wait strategy).

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.
Xuelei Ma MD

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 (Estimated)

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.
November 15, 2026

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.
November 15, 2027

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.
November 15, 2029

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).
October 27, 2026

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.
October 27, 2026

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 3, 2026

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.
November 3, 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.
October 27, 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.
October 1, 2026

More Information

Terms related to this study

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.
  • Approval No. 1646 (2026)

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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