Resectable MMR-deficient Solid TumorsPhase 2/3NEOASISNCT06279130

Pan-tumor Neoadjuvant Basket Study of Immune Check-point Inhibition and Novel Immuno-oncology Combinations

A Phase 2/3 study testing botensilimab, balstilimab and FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel) in people with Resectable MMR-deficient Solid Tumors and Resectable MMR-proficient Solid Tumors, run by The Netherlands Cancer Institute at 1 site in Netherlands.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts

Official record

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Trial summary

In this study, the efficacy of botensilimab and balstilimab in mismatch repair deficient (dMMR) and mismatch repair proficient (pMMR) tumors will be assessed. Read more about this study

Who is it for?: Ages 18 years and older
Conditions the study is for: Resectable MMR-deficient Solid Tumors, Resectable MMR-proficient Solid Tumors
What is being tested?: botensilimab, balstilimab and FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)
Type of treatment: Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 133 participants
Where: 1 siteNetherlands
Study dates: 29 Jan 2024to 29 Jan 2034
Phase: Phase 2/3
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

Signed written informed consent
Patients at least 18 years of age
Non-metastatic, newly diagnosed dMMR and pMMR cancers either fitting within a specific basket or in the "other" cohort (e.g. sarcoma, head and neck cancers, anal cancer, esophageal SCC)
In case of pMMR tumors: no indication for neoadjuvant therapy according to standard of care, unless adjuvant treatment is considered a standard of care alternative;
Eligible for study biopsy
World health organization (WHO) performance status of 0 or 1

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Screening laboratory tests must meet the following criteria and should be obtained within 7 days prior to randomization/registration: White blood cell count (WBC > 2.0 x 10^9/L, Absolute neutrophil count (ANC) > 1.5x10^9/L, platelets > 100 x 10^9/L, Hemoglobin > 5.0mmol/L. Transfusion is allowed to obtain an adequate hemoglobin level. Liver function tests: total bilirubin < 1.5 upper limit of normal (ULN) (except for subjects with Gilbert syndrome, who can have total bilirubin <3.0 mg/dL); alkaline phosphatase <1.5 ULN; transaminases (ASAT/ALAT) <3 x ULN; Lactate dehydrogenase (LDH) < 1.5x ULN; Creatinine clearance (Cockcroft-Gault) of >45 ml/min, Albumin > 3.0 g/dL
Women of childbearing potential (WOCBP)* must use appropriate method(s) of contraception. WOCBP should use an adequate method to avoid pregnancy for 20 weeks after the last dose of investigational drug, Non-childbearing potential is defined as:
Postmenopausal: ≥ 50 years of age and has not had menses for greater than 1 year.
Amenorrheic for ≥ 2 years without a hysterectomy and bilateral oophorectomy and a follicle- stimulating hormone value in the postmenopausal range upon pre-study(screening) evaluation.
Status is post-hysterectomy, bilateral oophorectomy, or tubal ligation.
Women of childbearing potential must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of cycle 1 day 1
Men who are sexually active with WOCBP must use any contraceptive method with a failure rate of less than 1% per year. Men receiving the study treatment and who are sexually active with WOCBP (excluding azoospermic men) will be instructed to adhere to contraception for a period of 28 weeks after the last dose of investigational drug and are not allowed to donate sperm during that timeframe.

Who cannot join

Signs of distant metastases on imaging and physical examination
Clinical obstruction
Clinical symptoms or radiological suspicion of perforation
Previous treatment with immune checkpoint inhibitors including but not limited to anti-CTLA4 or anti-PD1
Prior chemotherapy for any cancer
Radiotherapy prior to or planned post-surgery radiotherapy for disease under study

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Active malignancies other than disease under study within 3 years prior to inclusion, except for malignancies with a negligible recurrence rate (e.g. <10% in 5 years)
Allergies and Adverse Drug Reaction:
History of allergy to study drug components
History of severe hypersensitivity reaction to any monoclonal antibody
Intercurrent illnesses, including but not limited to infections, unstable angina pectoris
Underlying medical conditions that, in the investigator's opinion, will make the administration of the study drug hazardous or obscure the interpretation of toxicity determination of adverse events
Positive test for hepatitis B virus surface antigen (HBsAg) or hepatitis C virus ribonucleic acid (HCV antibody) indicating acute or chronic infection
History of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS)
Active autoimmune disease or a documented history of autoimmune disease, or other medical conditions requiring systemic steroid or immunosuppressive medications, except for subjects with vitiligo, diabetes mellitus type 1, hypothyroidism due to autoimmune condition only requiring hormone replacement, psoriasis or resolved childhood asthma/atopy not requiring systemic treatment
Conditions requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of study drug administration. Inhaled or topical steroids and adrenal replacement doses > 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease
Live vaccines in the 4 weeks prior to inclusion
Psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
Current pregnancy or breastfeeding
Specific for pMMR GEA cohort:
Known DPD deficiency; refer local clinical guidance, for DPD status recommendation prior to starting treatment.

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Marieke van de Belt, MsC contact

0205129111

m.vd.belt@nki.nl

Netherlands1 site, 1 recruiting

The Netherlands Cancer Institute
Amsterdam, North Holland, 1066 CX
Marieke van de Belt, MsC
Myriam Chalabi, MD PhD
Recruiting

Other trials in Netherlands

About this study

In this study, the efficacy of botensilimab and balstilimab in mismatch repair deficient (dMMR) and mismatch repair proficient (pMMR) tumors will be assessed.

Read the detailed description

The NEOASIS study is an adaptive, pan-cancer, single-center, open-label, basket study assessing the efficacy of botensilimab and balstilimab in patients with resectable dMMR and pMMR solid tumors of various origins. Patients will be included in baskets according to tumor type and mismatch repair (MMR) status and will receive 2 cycles of immunotherapy followed by surgery.

The trial will commence with two safety run-in cohorts: one for patients with dMMR tumors and one for patients with pMMR tumors that will run in parallel. These safety run-in cohort will be used to assess safety and feasibility of pre-operative botensilimab + balstilimab. Data from the safety run-in cohorts will be used to determine the dosing and scheduling to be used in the MMR-specific cohorts of the main study. Safety will be assessed according to dose limiting toxicities. In the run-in cohorts, the first five patients will receive botensilimab 25mg intravenously (IV) on Day1 plus balstilimab 450mg IV on Day1 and Day22. Patients 6-10 will receive botensilimab 50mg IV on Day1 plus balstilimab 450mg IV on Day1 and Day22 followed by surgery 8 weeks after registration.

After full accrual of the run-in cohorts, MMR-specific baskets including a "other cancers" basket will start accrual with the optimal dose and schedule as determined in the safety run-in followed by surgery 8 weeks after registration. The MMR-specific baskets are designed with a Simon's 2 stage design in which first 8 patients will be included, if in the first 8 patients >2 Major pathological responses are reported (defined as ≤10% residual viable tumor) accrual of 10 more patients will continue for a total of 18 patients per basket.

This study was amended (approved in December 2025) to add cohort 10 and cohort 11. In cohort 10, patients with pMMR GEA tumors will receive Botensilimab and Balstilimab in combination with FLOT. In cohort 11, patients with dMMR rectum tumors will receive Botensilimab and Balstilimab. We aim for organ preservation in this cohort. See "Arms and Interventions" for more.

Conditions: Resectable MMR-deficient Solid Tumors, Resectable MMR-proficient Solid Tumors
Being tested: botensilimab, balstilimab, FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

botensilimabDrug
Anti cytotoxic T-lymphocyte associated protein-4 (anti-CTLA4)
balstilimabDrug
Anti programmed cell death protein-1 (anti-PD1)
FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)Drug
5-Fluorouracil (2400mg/m2), leucovorin (200mg/m2), oxaliplatin (85mg/m2), docetaxel (50mg/m2).

Study groups in NCT06279130
Study group	Role	What they receive
Cohort 2: pMMR Safety run-in 1 - closed (accrual reached)	Experimental	5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 25mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in June 2024, cohort is closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 4: pMMR Safety run-in 2 - closed (accrual reached)	Experimental	5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 50mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in August 2024, cohort is closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 1: dMMR Safety run-in 1 - closed (accrual reached)	Experimental	5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 25mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in June 2025, cohort is closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 3: dMMR Safety run-in 2 - closed (accrual reached)	Experimental	5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 50mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Acrrual was reached in August 2024, cohort is closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 6: dMMR Colorectal basket - closed (accrual reached)	Experimental	Patients with resectable colon and rectal cancer will be treated with the regimen assesses as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Accrual was reached in July 2025, cohort is closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 5: dMMR Upper gastro-intestinal cancer basket	Experimental	Patients with resectable oesophageal (adenocarcinoma), gastro-oesophageal junction, gastric and small bowel cancer will be treated with the regimen assessed as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 7: dMMR "other cancers" basket	Experimental	Patients with resectable solid tumors of various origins such as but not limited to breast-, prostate-, bladder cancer, Head\&Neck SCC, oesophageal SCC and sarcoma will be treated with the regimen assessed as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 8: pMMR TNBC cohort	Experimental	Patients with resectable Triple Negative Breast Cancer will be treated with the regimen assessed as safe and feasible in the pMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 9: pMMR "other cancers" - cohort closed	Experimental	Patients with resectable pMMR tumors of various origins will be treated with the regimen assessed as safe and feasible in the pMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Accrual was halted after 8 patients in July 2025, not more then 2 major pathological responses were observed, cohort remains closed. Receives: Drug: botensilimab; Drug: balstilimab
Cohort 10: pMMR GEA basket	Experimental	Patients with pMMR gastro-, esophageal or GE-junction tumors will receive study treatment that consists of cycle 1) botensilimab 50mg plus balstilimab 240mg 2) FLOT + bal 240mg 3) FLOT plus bot 50mg/bal 240mg 4-5) FLOT + bal 240mg. Surgery will take place a maximum of 6 weeks after start last treatment cycle. Patients will receive 8mg dexamethasone as premedication for docetaxel on the first day of infusion, and no additional doses of dexamethasone are allowed in the following days as an anti-emetic. Post-surgery, patients may receive 4 additional cycles of FLOT according to the standard of care. Evaluation will be performed after the first 3 patients are treated; if the proposed treatment is deemed feasible and all patients received the intended chemotherapy regimen, accrual may continue with the next 3 patients. If the first three patients undergo surgery according to plan without delays that are considered immune-related, accrual may continue beyond six patients (max 21). Receives: Drug: botensilimab; Drug: balstilimab; Drug: FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)
Cohort 11: dMMR Rectal Organ Preservation basket	Experimental	Patients with stage I-III dMMR rectal adenocarcinoma who prefer organ preservation are eligible. The study treatment will consist of 1 cycle of combination therapy on day 1: botensilimab 50mg plus balstilimab 450mg, followed by 2 cycles of balstilimab 450mg monotherapy on day 22 and day 43. If at the 1st response evaluation at 10 weeks a limited response, no response or progressive disease is observed, treatment according to standard of care, which may consist of direct surgery or additional neoadjuvant therapy may be considered after discussion in the MDT and with the study team. Receives: Drug: botensilimab; Drug: balstilimab

What is being measured

The primary outcome is the main question the study is designed to answer.

Major pathological response rate
Percentage of patients in which a major pathologic response (MPR) is reported, defined as <10% residual viable tumor (RVT) in the resection specimen.
Measured: Week 8

Secondary outcomes (5)

Pathological response rates
Pathologic complete response (pCR) defined as no RVT in the primary tumor and locoregional lymph nodes; partial pathologic response (≤50% RVT) and no pathologic response (>50% RVT)
Measured: Week 8
Event free survival
Event-free survival defined as time from registration to the date of disease progression, local, regional or distant recurrence, occurrence of a second primary cancer or death from any cause.
Measured: 3 years
Disease free survival
Disease free survival defined as the time from surgery to disease recurrence during follow-up which consists of either local or regional recurrence, metastatic disease or disease-related death.
Measured: 3 years
Overall survival
Overall survival defined as time from registration until death from any cause.
Measured: 5 years
Radiological response
Radiological response measured according to RECIST 1.1
Measured: Week 8

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

29 Jan 202429 Jan 2034

First posted26 Feb 2024
Study start29 Jan 2024
Primary completion29 Jan 2029 (estimated)
Study completion29 Jan 2034 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for Resectable MMR-deficient Solid TumorsStudies of the same condition, open and under way.
More trials run by The Netherlands Cancer InstituteThe 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 2/3
Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Parallel groups
Model description: Basket, open-label
Masking: None (open label)
Enrolment: 133 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06279130
Sponsor's protocol ID: N23NEO
Acronym: NEOASIS
Status last verified: Mar 2026
First submitted: 13 Feb 2024
Last updated: 5 Mar 2026
Results posted: No
Data monitoring committee: Yes
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: No

Study at a glance

From the registry record, last updated by the sponsor on 5 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Pan-tumor Neoadjuvant Basket Study of Immune Check-point Inhibition and Novel Immuno-oncology Combinations
ClinicalTrials.gov ID: NCT06279130
Acronym / sponsor ID: NEOASIS / N23NEO
Conditions: Resectable MMR-deficient Solid Tumors, Resectable MMR-proficient Solid Tumors
Phase: Phase 2/3
Study type: Interventional
Recruitment status: Recruiting
Enrolment: 133 participants (estimated)
Lead sponsor: The Netherlands Cancer InstituteUniversity, hospital or other
Collaborators: Agenus Inc.
Study start: 29 Jan 2024 (actual)
Primary completion: 29 Jan 2029 (estimated)
Study completion: 29 Jan 2034 (estimated)
First posted: 26 Feb 2024 (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.

In this study, the efficacy of botensilimab and balstilimab in mismatch repair deficient (dMMR) and mismatch repair proficient (pMMR) tumors will be assessed.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Parallel groups
Masking: None (open label)
Number of arms: 11
Model description: Basket, open-label

Arm	Type	Receives
Cohort 2: pMMR Safety run-in 1 - closed (accrual reached)	Experimental	Drug: botensilimab, Drug: balstilimab5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 25mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in June 2024, cohort is closed.
Cohort 4: pMMR Safety run-in 2 - closed (accrual reached)	Experimental	Drug: botensilimab, Drug: balstilimab5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 50mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in August 2024, cohort is closed.
Cohort 1: dMMR Safety run-in 1 - closed (accrual reached)	Experimental	Drug: botensilimab, Drug: balstilimab5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 25mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Accrual was reached in June 2025, cohort is closed.
Cohort 3: dMMR Safety run-in 2 - closed (accrual reached)	Experimental	Drug: botensilimab, Drug: balstilimab5 Patients will be included and will be treated with 2 cycles of neoadjuvant immunotherapy consisting of 450mg balstilimab and 50mg botensilimab in Cycle 1 and 450mg balstilimab in Cycle 2 followed by surgery Acrrual was reached in August 2024, cohort is closed.
Cohort 6: dMMR Colorectal basket - closed (accrual reached)	Experimental	Drug: botensilimab, Drug: balstilimabPatients with resectable colon and rectal cancer will be treated with the regimen assesses as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Accrual was reached in July 2025, cohort is closed.
Cohort 5: dMMR Upper gastro-intestinal cancer basket	Experimental	Drug: botensilimab, Drug: balstilimabPatients with resectable oesophageal (adenocarcinoma), gastro-oesophageal junction, gastric and small bowel cancer will be treated with the regimen assessed as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients.
Cohort 7: dMMR "other cancers" basket	Experimental	Drug: botensilimab, Drug: balstilimabPatients with resectable solid tumors of various origins such as but not limited to breast-, prostate-, bladder cancer, Head\&Neck SCC, oesophageal SCC and sarcoma will be treated with the regimen assessed as safe and feasible in the dMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients.
Cohort 8: pMMR TNBC cohort	Experimental	Drug: botensilimab, Drug: balstilimabPatients with resectable Triple Negative Breast Cancer will be treated with the regimen assessed as safe and feasible in the pMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients.
Cohort 9: pMMR "other cancers" - cohort closed	Experimental	Drug: botensilimab, Drug: balstilimabPatients with resectable pMMR tumors of various origins will be treated with the regimen assessed as safe and feasible in the pMMR safety run-in. Treatment will be administered at day 1 and day 22 followed by surgery 8 weeks after registration. Accrual will be temporarily halted after accrual of the first 8 patients. If >2 major pathological responses are observed accrual will continue to a total of 18 patients. Accrual was halted after 8 patients in July 2025, not more then 2 major pathological responses were observed, cohort remains closed.
Cohort 10: pMMR GEA basket	Experimental	Drug: botensilimab, Drug: balstilimab, Drug: FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)Patients with pMMR gastro-, esophageal or GE-junction tumors will receive study treatment that consists of cycle 1) botensilimab 50mg plus balstilimab 240mg 2) FLOT + bal 240mg 3) FLOT plus bot 50mg/bal 240mg 4-5) FLOT + bal 240mg. Surgery will take place a maximum of 6 weeks after start last treatment cycle. Patients will receive 8mg dexamethasone as premedication for docetaxel on the first day of infusion, and no additional doses of dexamethasone are allowed in the following days as an anti-emetic. Post-surgery, patients may receive 4 additional cycles of FLOT according to the standard of care. Evaluation will be performed after the first 3 patients are treated; if the proposed treatment is deemed feasible and all patients received the intended chemotherapy regimen, accrual may continue with the next 3 patients. If the first three patients undergo surgery according to plan without delays that are considered immune-related, accrual may continue beyond six patients (max 21).
Cohort 11: dMMR Rectal Organ Preservation basket	Experimental	Drug: botensilimab, Drug: balstilimabPatients with stage I-III dMMR rectal adenocarcinoma who prefer organ preservation are eligible. The study treatment will consist of 1 cycle of combination therapy on day 1: botensilimab 50mg plus balstilimab 450mg, followed by 2 cycles of balstilimab 450mg monotherapy on day 22 and day 43. If at the 1st response evaluation at 10 weeks a limited response, no response or progressive disease is observed, treatment according to standard of care, which may consist of direct surgery or additional neoadjuvant therapy may be considered after discussion in the MDT and with the study team.

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (13 listed)

Signed written informed consent
Patients at least 18 years of age
Non-metastatic, newly diagnosed dMMR and pMMR cancers either fitting within a specific basket or in the "other" cohort (e.g. sarcoma, head and neck cancers, anal cancer, esophageal SCC)
In case of pMMR tumors: no indication for neoadjuvant therapy according to standard of care, unless adjuvant treatment is considered a standard of care alternative;
Eligible for study biopsy

Key exclusion criteria (21 listed)

Signs of distant metastases on imaging and physical examination
Clinical obstruction
Clinical symptoms or radiological suspicion of perforation
Previous treatment with immune checkpoint inhibitors including but not limited to anti-CTLA4 or anti-PD1
Prior chemotherapy for any cancer

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
botensilimabAnti cytotoxic T-lymphocyte associated protein-4 (anti-CTLA4)	Drug	Cohort 10: pMMR GEA basket, Cohort 11: dMMR Rectal Organ Preservation basket, Cohort 1: dMMR Safety run-in 1 - closed (accrual reached), Cohort 2: pMMR Safety run-in 1 - closed (accrual reached), Cohort 3: dMMR Safety run-in 2 - closed (accrual reached), Cohort 4: pMMR Safety run-in 2 - closed (accrual reached), Cohort 5: dMMR Upper gastro-intestinal cancer basket, Cohort 6: dMMR Colorectal basket - closed (accrual reached), Cohort 7: dMMR "other cancers" basket, Cohort 8: pMMR TNBC cohort, Cohort 9: pMMR "other cancers" - cohort closed
balstilimabAnti programmed cell death protein-1 (anti-PD1)	Drug	Cohort 10: pMMR GEA basket, Cohort 11: dMMR Rectal Organ Preservation basket, Cohort 1: dMMR Safety run-in 1 - closed (accrual reached), Cohort 2: pMMR Safety run-in 1 - closed (accrual reached), Cohort 3: dMMR Safety run-in 2 - closed (accrual reached), Cohort 4: pMMR Safety run-in 2 - closed (accrual reached), Cohort 5: dMMR Upper gastro-intestinal cancer basket, Cohort 6: dMMR Colorectal basket - closed (accrual reached), Cohort 7: dMMR "other cancers" basket, Cohort 8: pMMR TNBC cohort, Cohort 9: pMMR "other cancers" - cohort closed
FLOT (Fluorouracil+Leucovorin+Oxaliplatin+Docetaxel)5-Fluorouracil (2400mg/m2), leucovorin (200mg/m2), oxaliplatin (85mg/m2), docetaxel (50mg/m2).	Drug	Cohort 10: pMMR GEA basket

Primary outcome

Major pathological response rate
Time frame: Week 8
Percentage of patients in which a major pathologic response (MPR) is reported, defined as <10% residual viable tumor (RVT) in the resection specimen.

5 secondary outcomes

Pathological response rates
Time frame: Week 8
Event free survival
Time frame: 3 years
Disease free survival
Time frame: 3 years
Overall survival
Time frame: 5 years
Radiological response
Time frame: Week 8

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 5 Mar 2026.
Individual participant dataSharing planned: No

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.

Marieke van de Belt, MsC contact

0205129111

m.vd.belt@nki.nl

Myriam Chalabi, MD PhD principal investigator

The Netherlands Cancer Institute

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

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 13 inclusion and 21 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: looking for participants now, as of the sponsor's last update on 5 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Netherlands. Whether a site is taking part right now should be confirmed with that site. See every site.

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 combined phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

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 Marieke van de Belt, MsC (0205129111, m.vd.belt@nki.nl), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Major pathological response rate (time frame: Week 8). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06279130.

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 5 Mar 2026; AzTrials last refreshed its copy on 7 Nov 2026.