ClinicalTrials.gg
Active, not recruitingNCT03860272Updated Mar 30, 2026

Fc-Engineered Anti-CTLA-4 Monoclonal Antibody in Advanced Cancer

A Phase 1 interventional study of Botensilimab and Balstilimab in Advanced Cancer, Angiosarcoma and Colorectal Cancer Without Liver Metastases, sponsored by Agenus Inc.. Active, not recruiting at 18 sites in 2 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-30.

Sponsored by Agenus Inc. · Phase 1, Interventional, and Treatment

Phase
Phase 1
Study type
Interventional
Enrollment
499
Allocation
Non-randomized
Ages
18 Years and older
Sex
All
01

Study summary

This study is an open-label, Phase 1, multicenter study to evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamic (PD) profiles of a novel fragment crystallizable (Fc)-engineered immunoglobulin G1 anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA-4) human monoclonal antibody (botensilimab) monotherapy and in combination with an anti-programmed cell death protein-1 (PD-1) antibody (balstilimab), and to assess the maximum tolerated dose (MTD) in participants with advanced solid tumors. This study will also determine the recommended phase 2 dose (RP2D) of botensilimab monotherapy and in combination with balstilimab.

Read the detailed description

This Phase 1 study will enroll up to approximately 550 evaluable adult participants with refractory, advanced cancer (solid tumors).

The study will consist of a 3+3 dose escalation. Different dose levels of botensilimab, both monotherapy and in combination with balstilimab, will be evaluated in individual cohorts based upon dose. Each participant will remain in the cohort of the dose level and schedule assigned at study entry. Participants can be replaced for any reason other than a dose-limiting toxicity (DLT). Participants will receive treatment for ≤ 2 years or until progressive disease, unacceptable toxicity, or any criterion for stopping the study drug or withdrawal of trial occurs.

Additionally, the study is intended to further explore the safety, PK, PD, and clinical activity in selected cancer types at dose levels (botensilimab monotherapy and combination therapy with balstilimab) determined as potentially effective. Indications of interest include, but are not limited to, non-small-cell lung cancer, melanoma, endometrial cancer, ovarian cancer, angiosarcoma, colorectal cancer without liver metastases, prostate cancer, and fibrolamellar carcinoma.

02

Conditions studied

  • Advanced Cancer
  • Angiosarcoma
  • Colorectal Cancer Without Liver Metastases
  • Endometrial Cancer
  • Fibrolamellar Carcinoma
  • Non-small-cell Lung Cancer
  • Ovarian Cancer
  • Prostate Cancer

Keywords

  • Solid Tumors
  • Advanced Cancer
  • Open-label
  • Monotherapy
  • Combination Therapy
  • Anti-CTLA-4
  • Anti-PD-1
  • Immunotherapy
03

In context

Hemangiosarcoma

99 studies on the registry are indexed under Hemangiosarcoma; 16 are open to participants now.

This study's enrollment of 499 is above the median of 64 across 83 interventional studies indexed under Hemangiosarcoma.

Browse Hemangiosarcoma studies →

Lead sponsor

Agenus Inc. is the lead sponsor of 31 studies on the registry; 2 are open to participants now.

Of its 11 completed or terminated interventional studies of FDA-regulated products, 3 (27%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

Inclusion Criteria:

For inclusion in the trial, all of the following inclusion criteria must be fulfilled, as no waivers will be permitted:

  1. Provision of signed and dated written prior to any study specific procedures. Participation in pharmacogenomics testing is optional.
  2. or cytologically confirmed diagnosis of or locally advanced solid tumor for which no standard therapy is available or standard therapy has failed.
  3. on imaging based on 1.1, except for prostate cancer.
  4. of ≥ 3 months and performance status of 0 or 1.
  5. Adequate organ and bone marrow reserve function, as indicated by the following laboratory values:

    1. Adequate hematological function, defined as ≥ 1.5 × 10\^9/liter (L), count ≥ 100 × 10\^9/L, and ≥ 8 grams/deciliter without recent transfusion (defined as a transfusion that has occurred within 2 weeks of the hemoglobin measurement).
    2. Adequate liver function, defined as total level ≤ 1.5 × institutional (IULN) (except for participants with Gilbert syndrome who must have a total bilirubin level of ≤ 3.0 × IULN), ≤ 2.5 × IULN, and alanine aminotransferase ≤ 2.5 × IULN.
    3. Adequate renal function defined as creatinine ≤ 1.5 × IULN or measured or calculated ≥ 40 milliliters (mL)/minute per institutional standard. Assessment methods should be recorded.
    4. Adequate coagulation, defined as or prothrombin time ≤ 1.5 × IULN and activated partial thromboplastin time ≤ 1.5 × IULN (unless participant receiving anticoagulant therapy) or stable known coagulopathy with sponsor approval.
  6. A sufficient and adequate formalin-fixed paraffin embedded tumor tissue sample (fresh or ) collected since last treatment and before the first dose from a site not previously irradiated, if clinically feasible.
  7. Female participants of must have a negative serum pregnancy test at screening (within 72 hours of first dose of study medication). Non-childbearing potential is defined as 1 of the following:

    1. ≥ 45 years of age and has not had menses for > 1 year and there is no alternative medical cause.
    2. Amenorrheic for > 2 years without a hysterectomy and/or oophorectomy and follicle stimulating hormone value in the range upon pretrial (screening) evaluation.
    3. Status is post-hysterectomy, -oophorectomy, or -tubal ligation.
  8. Female participants of childbearing potential must be willing to use highly effective measures starting with the Screening visit through 90 days after last dose of study treatment. For the UK only, highly effective contraceptive measures are defined as follows:

    1. Combined (estrogen and progesterone containing) hormonal contraception associated with inhibition of ovulation.

      • Oral
      • Intravaginal
      • Transdermal
    2. Progesterone-only hormonal contraception associated with inhibition of ovulation.

      • Oral
      • Injectable
      • Implantable
    3. Intrauterine device
    4. Intrauterine hormone-releasing system
    5. Bilateral tubal occlusion
    6. Vasectomized partner
    7. Sexual abstinence
  9. Male participants with a female partner(s) of childbearing potential must agree to use highly effective contraceptive measures throughout the trial starting with the Screening visit through 90 days after the last dose of study treatment is received. Males with pregnant partners must agree to use a condom (which is not considered "highly effective"); no additional method of contraception is required for the pregnant partner. Note: Abstinence is acceptable if this is the established and preferred contraception method for the participant.

    The following inclusion criteria are in addition to the above criteria. If there are criteria below that differs from above, the below indication-specific criteria take precedence.

    Additional Inclusion Criteria for Angiosarcoma Cohort

  10. Histologically or cytologically confirmed diagnosis of metastatic or locally advanced angiosarcoma for which no standard therapy is available or standard therapy has failed.

    Additional Inclusion Criteria for the Hepatocellular Cancer (HCC) Cohort

  11. Histologically or cytologically confirmed diagnosis or radiological diagnosis following the guidelines from the American Association for the Study of Liver Diseases of metastatic or locally advanced HCC.
  12. Must have progressed while receiving, or following, programmed death-ligand 1 (PD(L)-1)-based therapy.
  13. score of A. Note: Participants on anticoagulant treatment would have an assigned value of 1 point when scoring prothrombin time/international normalized ratio so the overall Child-Pugh score is not adversely affected.
  14. Adequate organ and bone marrow reserve function as indicated by the following laboratory values:

    1. Platelet count ≥ 60 × 10\^6/cubic millimeter (mm\^3) and absolute neutrophil count ≥ 1,000 × 10\^6/L are acceptable provided that the investigator assesses these abnormalities as being due to liver disease.
    2. Adequate liver function, defined as aspartate aminotransferase and alanine aminotransferase ≤ 5 × IULN, bilirubin ≤ 2 × IULN.
  15. Participants are eligible to enroll if they have non-viral-HCC or if they have (HBV), or virus (HCV) related HCC, defined as follows:

    1. Chronic HBV infection as evidenced by detectable HBV surface antigen or HBV DNA. Participants with chronic HBV infection must be on antiviral therapy and have HBV DNA \< 500 international units/mL.
    2. Active or resolved HCV infection as evidenced by detectable HCV RNA or antibody.

    Additional Inclusion Criteria for the Non-Small Cell Lung Cancer (NSCLC) Cohort

  16. Histologically or cytologically confirmed diagnosis of metastatic or locally advanced NSCLC for which no standard therapy is available or standard therapy has failed:

    1. Adenocarcinoma or squamous cell carcinoma at the time of enrollment. If other histologies are also present, must be approved by the medical monitor prior to study entry.
    2. For participants without targetable alterations: Prior treatment with anti PD(L)-1-based therapy.
    3. Participants with targetable alterations (for example, estimated , anaplastic lymphoma kinase, Kirsten rat sarcoma virus-single point mutation with a glycine-to-cysteine substitution at codon 12, reactive oxygen species, mesenchymal epithelial transition factor receptor, etc.): must have received or be intolerant of at least one approved targeted therapy.

    Additional Inclusion Criteria for the Prostate Cancer Cohort

  17. Diagnosis of metastatic castrate resistant prostate cancer.
  18. Must have demonstrated serologic or radiographic progression on or following the most recent therapy in the setting of castrate-level testosterone (\< 50 nanograms per mL [ng/mL] and/or maintained on medical/surgical castration throughout) as defined by at least one of the following:

    1. Baseline PSA ≥ 2.0 ng/mL and 2 sequential rises in prostate-specific antigen (PSA) with each rising value being at least 1 week apart.
    2. Progression by RECIST 1.1.
    3. Progression by PCWG3 criteria for bone disease ("2+2" rule) with or without PSA progression.
  19. Must maintain castration status defined as serum testosterone \< 50 ng/mL. Must be either surgically castrate or on luteinizing hormone-releasing hormone analog for the duration of the study.

    Additional Inclusion Criteria for Breast Cancer

  20. Must have received PD-(L)1 therapy if indicated. Note: Premenopausal participants may continue ongoing ovarian suppression on study. Permitted agents are goserelin, triptorelin or analogs.

Exclusion Criteria:

For inclusion in the trial, participant must meet none of the following exclusion criteria, as no waivers will be permitted:

  1. Currently participating and receiving study therapy or has participated in a study of an agent and received study therapy or used an investigation device within 3 weeks of first dose of current study drug.
  2. Received prior systemic cytotoxic chemotherapy, biological therapy, radiotherapy, or major surgery within 3 weeks prior to first dose of study drug; for tyrosine kinase inhibitor or similar within 4 × half-life prior to first dose of study drug. A 1-week is permitted for palliative radiation to non-central nervous system disease, with Sponsor approval.
  3. Participants who have received prior therapy may be enrolled in selected indications upon agreement with the Sponsor.
  4. Persistent toxicity of version 5.0 Grade > 1 severity that is related to prior therapy. Note: Sensory neuropathy, hypothyroidism or alopecia of Grade ≤ 2 are acceptable. Other Grade 2 toxicities of prior treatments that are controlled with medication (for example, diabetes or hypertension) may be permitted with sponsor approval.
  5. Expected to require any other form of systemic or localized antineoplastic therapy while on trial (including maintenance therapy with another agent, radiation therapy, and/or surgical resection).
  6. History of:

    1. Severe (Grade ≥ 3) reaction to a fully human monoclonal antibodies
    2. Immune-related adverse event requiring treatment with systemic for > 7 days excluding Grade 1 or 2 rash.
    3. Interstitial lung disease or lung disease which may interfere with the assessment of pneumonitis.
    4. Uncontrolled asthma (that is, ≥ 3 features of partly controlled asthma)
    5. Pneumonitis that has required oral or IV corticosteroids.
  7. Receiving systemic corticosteroid therapy 1 week prior to the first dose of study drug or receiving any other form of systemic medication. Note: Corticosteroid use as a premedication for IV contrast allergies/reactions is allowed. Participants who are receiving daily corticosteroid replacement therapy are also an exception to this rule. Daily prednisone at doses of ≤ 7.5 mg or equivalent hydrocortisone dose are examples of permitted replacement therapy. Use of inhaled or topical corticosteroids is permitted.
  8. or with the following exceptions: Note: Brain metastases which have been treated with either surgical resection or stereotactic radio surgery. These participants must be off steroids ≥ 10 days prior to enrollment for the purpose of managing their brain metastases. Repeat brain imaging following surgical resection or stereotactic radiosurgery is not required if their last brain magnetic resonance imaging is within screening window. Note: Untreated isolated brain metastases that are too small for treatment by surgical resection or stereotactic radiosurgery (that is, 1-2 mm) and/or of uncertain etiology are potentially eligible but must be approved by the sponsor.
  9. Active or history of disease that requires systemic treatment within 2 years of the start of study drug (that is, with use of disease-modifying agents, corticosteroids, or immunosuppressive drugs). Note: Participants with autoimmune conditions requiring hormone replacement therapy or topical treatments are eligible.
  10. Has had an allogeneic tissue/solid organ transplant, except for corneal transplants.
  11. Active infection requiring systemic treatment.
  12. Known history of type 1 or 2 antibodies.
  13. Known active infection with hepatitis B and/or hepatitis C virus.
  14. (that is, active) cardiovascular disease: cerebral vascular accident/stroke or myocardial infarction within 6 months of enrollment, unstable angina, congestive heart failure ( class ≥ II), or serious uncontrolled cardiac arrhythmia requiring medication.
  15. History or current evidence of any condition, therapy, any active infections, or laboratory abnormality that might confound the results of the trial, interfere with the participant's participation for the full duration of the trial, or is not in the best interest of the participant to participate, in the opinion of the treating Investigator.
  16. Known psychiatric or substance abuse disorder that would interfere with cooperation with the requirements of the study.
  17. Legally incapacitated or has limited legal capacity.
  18. Pregnant or breastfeeding.
  19. Concurrent requiring treatment or history of prior malignancy active within 2 years prior to the first dose of study treatment. Exceptions: participants with completely resected prior early-stage basal/squamous cell skin cancer or treated cervical carcinoma in situ.

    The following exclusion criteria are in addition to the above criteria. If there are criteria below that differs from above, the below indication-specific criteria take precedence.

    Additional Exclusion Criteria for the HCC Cohort

  20. Received locoregional therapy (for example, transcatheter chemoembolization, radiation, surgery) within 6 weeks or yttrium-90 within 12 weeks.
  21. Hepatic encephalopathy within the last 6 months requiring admission or initiation of or intensification of therapy. Participants taking rifaximin/lactulose as encephalopathy prophylaxis are allowed as long as they have not had clinically evident encephalopathy in the past 6 months.
  22. Gastro-esophageal varices bleeding in the last 6 months.
  23. Ascites requiring paracentesis within the last 3 months. Participants with previous ascites that is managed with stable doses of diuretics and have a Child Pugh score of A are allowed.

    Exclusion Criterion Specific for the UK

  24. Hypersensitivity to the active ingredient or any other component of the investigational medicinal products.
Terms in these criteria, in plain language(37)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Histologically or cytologically confirmed

The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).

Your pathology report is the document that shows this.

Metastases

Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.

Measurable disease

The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.

The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.

RECIST

The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.

“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.

Life expectancy

The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.

ECOG performance status

A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.

0
Fully active, no restrictions.
1
Limited in strenuous activity, but walking and able to do light work, such as housework or office work.
2
Walking and able to look after yourself, but unable to work; up and about more than half of waking hours.
3
Able to look after yourself only in part; in bed or a chair more than half of waking hours.
4
Unable to look after yourself at all; in bed or a chair all day.

Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.

Absolute neutrophil count (ANC)

The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.

It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.

Platelets

Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.

Hemoglobin (Hb)

The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).

Bilirubin

A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.

Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.

ULN (upper limit of normal)

The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.

“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

Creatinine clearance (CrCl)

How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.

INR, PT and aPTT (clotting tests)

Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.

Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.

Biopsy and archival tissue

A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.

Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Postmenopausal

Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Child-Pugh class

A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.

Hepatitis B tests

Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.

Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

GFR and eGFR (kidney filtering)

GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².

Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Washout period

A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.

PD-1, PD-L1 and checkpoint inhibitors

PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.

PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.

CTCAE grade

The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.

1
Mild.
2
Moderate.
3
Severe.
4
Life-threatening.
5
Death due to the event.

“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

Immunosuppression

A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.

Read whether the line is about a condition or about medicines, and which medicines and doses it means.

Brain metastases

Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).

Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.

Leptomeningeal disease

Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.

Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.

Autoimmune disease

A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.

Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.

HIV

The human immunodeficiency virus, which weakens the immune system.

Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

NYHA class (heart failure)

The New York Heart Association’s four classes of how much heart failure limits physical activity.

I
No limits: ordinary activity causes no undue tiredness or breathlessness.
II
Slight limits: comfortable at rest, ordinary activity causes symptoms.
III
Marked limits: comfortable at rest, less than ordinary activity causes symptoms.
IV
Symptoms even at rest; any activity makes them worse.

Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

05

Study design

Phase
Phase 1
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Single group
Masking
None (open label)
Enrollment
499 participants (actual)

Study arms

  • Experimental
    3-Week Monotherapy

    3+3 Dose escalation: botensilimab, every 3 weeks, starting at dose level 0.1 milligrams/kilogram (mg/kg) up to 4 mg/kg, administered intravenously (IV) for up to 2 years.

    Drug: Botensilimab

  • Experimental
    6-Week Monotherapy

    3+3 Dose escalation: botensilimab, every 6 weeks, starting at dose level 1 mg/kg up to 4 mg/kg, administered IV for up to 2 years.

    Drug: Botensilimab

  • Experimental
    6-Week Combination Therapy

    3+3 Dose escalation: balstilimab, every 2 weeks, at dose level 3 mg/kg in combination with botensilimab, every 6 weeks, starting at dose level 0.1 mg/kg up to 4 mg/kg, administered IV for up to 2 years. Participants enrolled at sites in the United Kingdom (UK) may have the option for extended treatment. An additional cohort will investigate balstilimab, every 3 weeks, at 450 mg in combination with botensilimab every 6 weeks, at 150 mg, administered IV for up to 2 years.

    Drug: Botensilimab · Drug: Balstilimab

Interventions

  • An Fc-engineered anti-CTLA-4 monoclonal antibody

    Also known as: AGEN1181, Anti-CTLA-4

  • A fully human monoclonal anti-PD-1 antibody

    Also known as: AGEN2034, Anti-PD-1

06

What researchers measure

Primary outcomes

  1. Incidence Of Treatment-emergent Adverse Events (TEAEs)

    TEAEs will include adverse events of special interest, immune-related adverse events, and adverse drug reactions, according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 5.0.

    Time frame: First dose through 90 days following last study dose (up to 2 years)

  2. DLT Of Botensilimab

    DLTs will include any Grade 2 or greater drug related toxicity for all dose groups, according to NCI CTCAE version 5.0 and protocol specifications.

    Time frame: First 28 days of treatment

  3. RP2D Of Botensilimab

    MTD based on DLT occurrence at DLT period (28 days after first dose) and all TEAEs seen through 90 days following last study dose.

    Time frame: First dose through 90 days following last study dose

Secondary outcomes

  1. Objective Response Rate (ORR) According To Response Evaluation Criteria In Solid Tumors Version 1.1 (RECIST 1.1)

    Confirmed ORR will be in the analysis population.

    Time frame: First dose through up to 2 years

  2. ORR According to Prostate Cancer Working Group 3 (PCWG3)

    Confirmed ORR will be in the analysis population.

    Time frame: First dose through up to 2 years

  3. Duration Of Response (DOR) According To RECIST 1.1

    Time frame: From first dose to first observation of documented disease progression (or death within 12 weeks of last tumor assessment) (up to 2 years)

  4. DOR According to PCWG3

    Time frame: From first dose to first observation of documented disease progression (or death within 12 weeks of last tumor assessment) (up to 2 years)

  5. Disease Control Rate (DCR) According To RECIST 1.1

    DCR will include complete response, partial response, and stable disease.

    Time frame: First study dose through 24 weeks

  6. DCR According to PCWG3

    DCR will include complete response, partial response, and stable disease.

    Time frame: First study dose through 24 weeks

  7. Progression-free Survival (PFS) According To RECIST 1.1

    PFS time will be assessed.

    Time frame: First study dose to first observation of documented disease progression (or death within 12 weeks of last tumor assessment) (up to 2 years)

  8. PFS According to PCWG3

    PFS time will be assessed.

    Time frame: First study dose to first observation of documented disease progression (or death within 12 weeks of last tumor assessment) (up to 2 years)

  9. Overall Survival Time

    Duration of survival will be assessed.

    Time frame: First study dose through up to 3 years

  10. Maximum Drug Concentration At Steady-state (Cmax-ss)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  11. Minimum Drug Concentration At Steady-state (Cmin-ss)

    Serum botensilimab concentration measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  12. Area Under The Drug Concentration-time Curve Within Time Span t1 To t2 At Steady-state (AUC(t1-t2)-ss)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  13. Area Under The Drug Concentration-time Curve From Time Zero To Infinity [AUC(0-∞)]

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  14. Terminal Elimination Rate Constant (λz)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  15. Terminal Elimination Half-life (t1/2)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  16. Systemic Clearance (CL)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  17. Volume Of Distribution (Vd)

    Serum botensilimab concentrations measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

  18. Anti-drug Antibodies (ADAs)

    Serum botensilimab ADAs measured throughout the study

    Time frame: First study dose (pre-dose) through 3 months following last study dose (up to 2 years)

07

Study locations

18 sites
08

References and documents

Publications

  • Bengala E, Santini D, Picone V. Refractory microsatellite-stable metastatic colorectal cancer: a comparison between botensilimab + balstilimab and current standard of care. Immunooncol Technol. 2025 Nov 28;29:101558. doi: 10.1016/j.iotech.2025.101558. eCollection 2026 Mar. PubMed 41502912 ↗
  • Wilky BA, Schwartz GK, Gordon MS, El-Khoueiry AB, Bullock AJ, Henick B, Agulnik M, Singh A, Mahadevan D, Stebbing J, Delepine C, Chand D, Avagyan M, Wu W, Johnson B, Grossman JE, O'Day S, Trent JC, Jones RL, Tsimberidou AM. Botensilimab (Fc-enhanced anti-cytotoxic lymphocyte-association protein-4 antibody) Plus Balstilimab (anti-PD-1 antibody) in Patients With Relapsed/Refractory Metastatic Sarcomas. J Clin Oncol. 2025 Apr 10;43(11):1358-1368. doi: 10.1200/JCO-24-02524. Epub 2025 Jan 27. PubMed 39869830 ↗
  • Bullock AJ, Schlechter BL, Fakih MG, Tsimberidou AM, Grossman JE, Gordon MS, Wilky BA, Pimentel A, Mahadevan D, Balmanoukian AS, Sanborn RE, Schwartz GK, Abou-Alfa GK, Segal NH, Bockorny B, Moser JC, Sharma S, Patel JM, Wu W, Chand D, Rosenthal K, Mednick G, Delepine C, Curiel TJ, Stebbing J, Lenz HJ, O'Day SJ, El-Khoueiry AB. Botensilimab plus balstilimab in relapsed/refractory microsatellite stable metastatic colorectal cancer: a phase 1 trial. Nat Med. 2024 Sep;30(9):2558-2567. doi: 10.1038/s41591-024-03083-7. Epub 2024 Jun 13. PubMed 38871975 ↗

Individual participant data

Plan to share: No

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from Mar 2019 to primary completion in Jan 2025, 69 months.

How these figures are worked out, and which studies are left out of them.

Registered
Feb 12, 2019
First posted
Mar 1, 2019
StartActual
Mar 20, 2019
Primary completionActual
Jan 13, 2025
CompletionEst.
Dec 2027
Last update
Mar 30, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Mar 30, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03860272
Lead sponsor
Agenus Inc.
Responsible party
Sponsor
First posted
Mar 1, 2019
Start date
Mar 20, 2019
Primary completion
Jan 13, 2025
Completion
Dec 2027 (estimated)
Last update
Mar 30, 2026

Study contacts

Medical Director
study director · Agenus Inc.

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is active, not recruiting, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.

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Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Studies of the drug tested here: Botensilimab

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