NCT06279130

Brief Summary

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

Trial Health

77
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
133

participants targeted

Target at P75+ for phase_2

Timeline
94mo left

Started Jan 2024

Longer than P75 for phase_2

Geographic Reach
1 country

1 active site

Status
recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Progress23%
Jan 2024Jan 2034

Study Start

First participant enrolled

January 29, 2024

Completed
15 days until next milestone

First Submitted

Initial submission to the registry

February 13, 2024

Completed
13 days until next milestone

First Posted

Study publicly available on registry

February 26, 2024

Completed
4.9 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

January 29, 2029

Expected
5 years until next milestone

Study Completion

Last participant's last visit for all outcomes

January 29, 2034

Last Updated

March 5, 2026

Status Verified

March 1, 2026

Enrollment Period

5 years

First QC Date

February 13, 2024

Last Update Submit

March 3, 2026

Conditions

Outcome Measures

Primary Outcomes (1)

  • 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.

    Week 8

Secondary Outcomes (5)

  • Pathological response rates

    Week 8

  • Event free survival

    3 years

  • Disease free survival

    3 years

  • Overall survival

    5 years

  • Radiological response

    Week 8

Study Arms (11)

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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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.

Drug: botensilimabDrug: 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).

Drug: botensilimabDrug: balstilimabDrug: 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.

Drug: botensilimabDrug: balstilimab

Interventions

Anti cytotoxic T-lymphocyte associated protein-4 (anti-CTLA4)

Cohort 10: pMMR GEA basketCohort 11: dMMR Rectal Organ Preservation basketCohort 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 basketCohort 6: dMMR Colorectal basket - closed (accrual reached)Cohort 7: dMMR "other cancers" basketCohort 8: pMMR TNBC cohortCohort 9: pMMR "other cancers" - cohort closed

Anti programmed cell death protein-1 (anti-PD1)

Cohort 10: pMMR GEA basketCohort 11: dMMR Rectal Organ Preservation basketCohort 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 basketCohort 6: dMMR Colorectal basket - closed (accrual reached)Cohort 7: dMMR "other cancers" basketCohort 8: pMMR TNBC cohortCohort 9: pMMR "other cancers" - cohort closed

5-Fluorouracil (2400mg/m2), leucovorin (200mg/m2), oxaliplatin (85mg/m2), docetaxel (50mg/m2).

Cohort 10: pMMR GEA basket

Eligibility Criteria

Age18 Years+
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • 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
  • 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.

You may not qualify if:

  • 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
  • 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
  • +4 more criteria

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

The Netherlands Cancer Institute

Amsterdam, North Holland, 1066 CX, Netherlands

RECRUITING

MeSH Terms

Interventions

balstilimab

Study Officials

  • Myriam Chalabi, MD PhD

    The Netherlands Cancer Institute

    PRINCIPAL INVESTIGATOR

Central Study Contacts

Marieke van de Belt, MsC

CONTACT

Study Design

Study Type
interventional
Phase
phase 2
Allocation
NON RANDOMIZED
Masking
NONE
Purpose
TREATMENT
Intervention Model
PARALLEL
Model Details: Basket, open-label
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

February 13, 2024

First Posted

February 26, 2024

Study Start

January 29, 2024

Primary Completion (Estimated)

January 29, 2029

Study Completion (Estimated)

January 29, 2034

Last Updated

March 5, 2026

Record last verified: 2026-03

Data Sharing

IPD Sharing
Will not share

Locations