Neoplasms, RectalPhase 3DuraSTARNCT07740720
A Study of the Duration of Dostarlimab in Untreated Mismatch Repair Deficient (dMMR)/ Microsatellite Instability-high (MSI-H) Locally Advanced Rectal Cancer
A Phase 3 study testing Dostarlimab in people with Neoplasms, Rectal, run by GlaxoSmithKline.
Trial summary
This study is conducted in adults with rectal cancer that has a certain genetic type. The main goal is to find out whether a longer treatment period with dostarlimab can help more participants have a complete response to treatment and avoid standard treatments like chemotherapy, radiation treatment, or surgery. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Neoplasms, Rectal
- What is being tested?
- Dostarlimab
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 90 participants
- Where
- No sites listed yet
- Study dates
- 17 Sep 2026to 31 Dec 2029
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Has histologically confirmed Stage II to III (T3-T4, N0, or T any, N+) locally advanced rectal adenocarcinoma.
- Has radiologically and endoscopically evaluable disease.
- Has a tumor demonstrating the presence of either:
- dMMR status; MMR status must be assessed by immunohistochemistry for MMR protein expression (MLH1, MSH2, MSH6, PMS2) where loss of 1 or more proteins indicates dMMR; MMR status will be determined locally; or
- MSI-H phenotype as determined by polymerase chain reaction or by tissue next generation sequencing; MSI-H will be determined locally.
- Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
- Has adequate organ function.
Who cannot join
- Has received prior radiation therapy, systemic therapy, or surgery for management of rectal cancer.
- Has a tumor that, in the investigator's judgment, is causing symptomatic bowel obstruction or otherwise requires urgent/emergent local intervention. Participants with a history of bowel obstruction are eligible after obstruction is relieved by a diverting stoma (defunctioning colostomy). Patients with a history of bowel obstruction in the context of current rectal cancer diagnosis and treated with stenting are not eligible.
- Has an active autoimmune disease that has required systemic treatment in the past 2 years (i.e., with use of disease-modifying agents, corticosteroids, or immunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment.
- Has undergone any major surgical procedure, open biopsy, or experienced significant traumatic injury within 28 days prior to enrollment.
- Is receiving any other anticancer or experimental therapy.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: A Phase 3b, Open-label Study Investigating the Duration of Neoadjuvant Dostarlimab Monotherapy in Participants With Untreated Stage II/III dMMR/MSI-H Locally Advanced Rectal Cancer
This study is conducted in adults with rectal cancer that has a certain genetic type. The main goal is to find out whether a longer treatment period with dostarlimab can help more participants have a complete response to treatment and avoid standard treatments like chemotherapy, radiation treatment, or surgery. Scans and endoscopy tests will be conducted to see if the tumor disappears and how long the cancer stays under control. The study will also collect information on side effects and health outcomes after dostarlimab.
- Conditions
- Neoplasms, Rectal
- Being tested
- Dostarlimab
- Keywords
- GSK4057190, Dostarlimab, dMMR, MSI-H, Locally advanced rectal cancer, DuraSTAR, PD-1, LARC, Anti-PD1
- Medical subject headings
- Rectal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
DostarlimabBiological
Also called GSK4057190, dostarlimab-gxly, TSR-042
Dostarlimab will be administered.
| Study group | Role | What they receive |
|---|---|---|
| Dostarlimab | Experimental | Not described Receives: Biological: Dostarlimab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage of participants who achieve clinical complete response (cCR) amongst participants who receive > 9 cycles (> 6 months) of dostarlimab monotherapy by investigator assessment
Measured: Up to 168 weeks
Secondary outcomes (6)
Overall cCR rate by investigator assessment
Overall cCR rate is defined as the percentage of participants achieving cCR by investigator assessment at any disease assessment, regardless of duration of dostarlimab therapy among all enrolled participants.
Measured: Up to 171 weeks
Number of participants with sustained clinical complete response at 12 months (cCR12) as assessed by investigator
cCR12 is defined as achievement and maintenance of cCR for 12 months from the disease assessment after the last dose of study intervention that first demonstrates cCR by investigator assessment.
Measured: Up to 171 weeks
Objective response rate (ORR) as assessed by investigator
ORR is defined as the percentage of participants who achieve a best clinical response of partial response (PR), near complete response (nCR), or clinical complete response (cCR) at any disease assessment.
Measured: Up to 171 weeks
Number of participants with composite cCR12 and pathologic complete response (pCR) as assessed by investigator
The composite endpoint of cCR12 and pCR is defined as the number of participants who either achieve cCR12, or achieve pCR after receiving dostarlimab (before receiving standard of care)
Measured: Up to 171 weeks
Time to cCR
Time to cCR is defined as the time from the first dose of study intervention to the time of first cCR as assessed by the investigator.
Measured: Up to 171 weeks
Number of participants with treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), immune-mediated adverse event (imAEs), and AEs leading to death or discontinuation of study intervention by severity
Measured: Up to 171 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Aug 2026
- Study start17 Sep 2026 (estimated)
- Primary completion12 Dec 2029 (estimated)
- Study completion31 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Neoplasms, RectalStudies of the same condition, open and under way.
- More trials run by GlaxoSmithKlineThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- GlaxoSmithKline
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07740720
- Sponsor's protocol ID
- 308360
- Other IDs
- 2026-526683-21
- Acronym
- DuraSTAR
- Status last verified
- Jul 2026
- First submitted
- 24 Jul 2026
- Last updated
- 3 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Study Sponsor will assess requests from qualified researchers for anonymized individual patient-level data and related study documents. Data sharing is subject to certain criteria, conditions, and exceptions. For further information, refer to https://www.gsk-studyregister.com/gsk-patient-level-data-sharing-july2025.pdf
Study at a glance
From the registry record, last updated by the sponsor on 3 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 3b, Open-label Study Investigating the Duration of Neoadjuvant Dostarlimab Monotherapy in Participants With Untreated Stage II/III dMMR/MSI-H Locally Advanced Rectal Cancer
- ClinicalTrials.gov ID
- NCT07740720
- Acronym / sponsor ID
- DuraSTAR / 308360
- Conditions
- Neoplasms, Rectal
- Keywords
- GSK4057190, Dostarlimab, dMMR, MSI-H, Locally advanced rectal cancer, DuraSTAR, PD-1, LARC
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 90 participants (estimated)
- Lead sponsor
- GlaxoSmithKlineIndustry (pharma, biotech, devices)
- Study start
- 17 Sep 2026 (estimated)
- Primary completion
- 12 Dec 2029 (estimated)
- Study completion
- 31 Dec 2029 (estimated)
- First posted
- 3 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is conducted in adults with rectal cancer that has a certain genetic type. The main goal is to find out whether a longer treatment period with dostarlimab can help more participants have a complete response to treatment and avoid standard treatments like chemotherapy, radiation treatment, or surgery. Scans and endoscopy tests will be conducted to see if the tumor disappears and how long the cancer stays under control. The study will also collect information on side effects and health outcomes after dostarlimab.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Dostarlimab | Experimental | Biological: Dostarlimab |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Has histologically confirmed Stage II to III (T3-T4, N0, or T any, N+) locally advanced rectal adenocarcinoma.
- Has radiologically and endoscopically evaluable disease.
- Has a tumor demonstrating the presence of either:
- Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
- Has adequate organ function.
Key exclusion criteria (5 listed)
- Has received prior radiation therapy, systemic therapy, or surgery for management of rectal cancer.
- Has a tumor that, in the investigator's judgment, is causing symptomatic bowel obstruction or otherwise requires urgent/emergent local intervention. Participants with a history of bowel obstruction are eligible after obstruction is relieved by a diverting stoma (defunctioning colostomy). Patients with a history of bowel obstruction in the context of current rectal cancer diagnosis and treated with stenting are not eligible.
- Has an active autoimmune disease that has required systemic treatment in the past 2 years (i.e., with use of disease-modifying agents, corticosteroids, or immunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment.
- Has undergone any major surgical procedure, open biopsy, or experienced significant traumatic injury within 28 days prior to enrollment.
- Is receiving any other anticancer or experimental therapy.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| DostarlimabAlso: GSK4057190, dostarlimab-gxly, TSR-042Dostarlimab will be administered. | Biological | Dostarlimab |
Primary outcome
Percentage of participants who achieve clinical complete response (cCR) amongst participants who receive > 9 cycles (> 6 months) of dostarlimab monotherapy by investigator assessment
Time frame: Up to 168 weeks
6 secondary outcomes
Overall cCR rate by investigator assessment
Time frame: Up to 171 weeks
Number of participants with sustained clinical complete response at 12 months (cCR12) as assessed by investigator
Time frame: Up to 171 weeks
Objective response rate (ORR) as assessed by investigator
Time frame: Up to 171 weeks
Number of participants with composite cCR12 and pathologic complete response (pCR) as assessed by investigator
Time frame: Up to 171 weeks
Time to cCR
Time frame: Up to 171 weeks
Number of participants with treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), immune-mediated adverse event (imAEs), and AEs leading to death or discontinuation of study intervention by severity
Time frame: Up to 171 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Aug 2026.
- Individual participant dataSharing planned: Yes. Study Sponsor will assess requests from qualified researchers for anonymized individual patient-level data and related study documents. Data sharing is subject to certain criteria, conditions, and exceptions. For further information, refer to https://www.gsk-studyregister.com/gsk-patient-level-data-sharing-july2025.pdf
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Dostarlimab in people with Neoplasms, Rectal, run by GlaxoSmithKline.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 3 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact US GSK Clinical Trials Call Center (877-379-3718, GSKClinicalSupportHD@gsk.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Percentage of participants who achieve clinical complete response (cCR) amongst participants who receive > 9 cycles (> 6 months) of dostarlimab monotherapy by investigator assessment (time frame: Up to 168 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Aug 2026.