Sponsor: Michael B. Atkins, MD (other)
Phase: 2
Start date: Sept. 25, 2023
Planned enrollment: 120
Balstilimab (AGEN2034; BAL) is an investigational, fully human IgG4 monoclonal antibody targeting PD‑1. It has been evaluated as monotherapy and in combination with the CTLA‑4 antibody zalifrelimab in previously treated recurrent/metastatic cervical cancer, with published phase 2 data. A U.S. BLA for second‑line cervical cancer was submitted in April 2021, accepted for Priority Review in June 2021, and voluntarily withdrawn in October 2021 after full approval of pembrolizumab in the same setting; development has continued in combinations. (pubmed.ncbi.nlm.nih.gov)
Cervical cancer (previously treated, recurrent/metastatic)
Balstilimab monotherapy (open‑label, single‑arm, phase 2; n=140 efficacy‑evaluable): Confirmed ORR 15.0% (95% CI, 10.0–21.8), including 3.6% complete responses; median duration of response (DoR) 15.4 months. ORR 20.0% in PD‑L1–positive tumors and 7.9% in PD‑L1–negative tumors. DCR 49.3%. Dosing: 3 mg/kg IV every 2 weeks (up to 24 months). (pubmed.ncbi.nlm.nih.gov)
Balstilimab + zalifrelimab (open‑label, single‑arm, phase 2; n=125 efficacy‑evaluable): Confirmed ORR 25.6% (95% CI, 18.8–33.9), with 10 complete and 22 partial responses; median DoR not reached at median follow‑up 21 months (response durability 64.2% at 12 months). ORR 32.8% in PD‑L1–positive and 9.1% in PD‑L1–negative tumors. DCR 52%. Dosing: balstilimab 3 mg/kg Q2W + zalifrelimab 1 mg/kg Q6W (up to 24 months). (pubmed.ncbi.nlm.nih.gov)
Other tumor types (early signals)
Note: Additional early‑phase combination studies with botensilimab (next‑generation CTLA‑4) have reported responses in ovarian and other solid tumors, but these are primarily from conference presentations and company communications and remain exploratory. (cancernetwork.com)
Balstilimab monotherapy (phase 2 cervical cancer): Most common grade ≥3 treatment‑related AEs were immune‑mediated enterocolitis (3.1%) and diarrhea (1.9%). Overall safety was consistent with PD‑1 inhibitors. (pubmed.ncbi.nlm.nih.gov)
Balstilimab + zalifrelimab (phase 2 cervical cancer): Grade ≥3 treatment‑related AEs occurred in 20.0%; common immune‑mediated AEs included hypothyroidism (14.2%) and hyperthyroidism (7.1%). Serious TRAEs occurred in 10.3%; three treatment‑related deaths (pneumonitis, immune‑mediated nephritis, diabetes mellitus) were reported. (ascopubs.org)
Doxorubicin + zalifrelimab + balstilimab in soft tissue sarcoma: Grade 3/4 TRAEs in 45%; immune‑mediated AEs requiring immunosuppression in 9%. (pubmed.ncbi.nlm.nih.gov)
Notes: Balstilimab is not FDA‑approved as of October 7, 2025. Efficacy and safety summaries above reflect non‑randomized trials; comparative effectiveness versus approved PD‑1 inhibitors has not been established. (investor.agenusbio.com)
Last updated: Oct 2025
Botensilimab (AGEN1181; BOT) is an Fc‑engineered, next‑generation anti–CTLA‑4 monoclonal antibody being developed primarily in combination with the anti–PD‑1 antibody balstilimab (BAL). Early clinical activity has been reported across “cold” or immunotherapy‑refractory tumors, especially microsatellite‑stable (MSS) metastatic colorectal cancer (mCRC) without active liver metastases and in relapsed/refractory metastatic sarcomas. Fast Track designation has been granted by the FDA for BOT/BAL in non‑MSI‑H mCRC without active liver involvement. (pmc.ncbi.nlm.nih.gov)
Microsatellite‑stable metastatic colorectal cancer (MSS mCRC)
Relapsed/refractory metastatic sarcomas
Neoadjuvant, resectable colorectal cancer
Combination with chemotherapy
Notes: Reported efficacy in MSS mCRC is largely confined to patients without active liver metastases in early‑phase studies; definitive benefit will require results from randomized phase 3 testing. (pmc.ncbi.nlm.nih.gov)
Last updated: Oct 2025
Goal: Evaluate whether the investigational combination of botensilimab (Fc‑enhanced anti‑CTLA‑4) plus balstilimab (anti‑PD‑1) improves objective response rate versus the standard ipilimumab plus nivolumab regimen in previously untreated metastatic clear cell renal cell carcinoma (ccRCC), and characterize safety and key time-to-event outcomes.
Patients: Adults (≥18) with histologically confirmed advanced or metastatic ccRCC, treatment naïve for systemic therapy, measurable disease by RECIST 1.1, ECOG 0–2, and adequate organ function. All IMDC risk groups are eligible with stratification by risk; initial analyses focus on intermediate/poor risk. Controlled HIV and resolved/controlled HBV/HCV are allowed per protocol. Key exclusions include prior checkpoint inhibitor or VEGF/VEGFR therapy, uncontrolled CNS metastases, recent radiotherapy or major surgery, active autoimmune disease requiring systemic therapy, significant cardiovascular disease, and pregnancy or breastfeeding.
Design: Randomized, open-label, multicenter phase II study using a Simon two-stage design; 2:1 allocation to investigational versus control arms. Treatment continues until toxicity, progression, or a maximum of 96 weeks (12-week induction, 84-week maintenance).
Treatments: Arm A (experimental): botensilimab plus balstilimab. Induction: Cycle 1 botensilimab 75 mg IV with balstilimab 450 mg IV on Days 1 and 22; Cycle 2 balstilimab 450 mg IV on Days 1 and 22 only. Maintenance: Cycles 3–4 botensilimab 75 mg IV Day 1 with balstilimab 450 mg IV on Days 1, 22, 43, 64; Cycles 5–9 balstilimab 450 mg IV on Days 1, 22, 43, 64. Botensilimab is an investigational Fc‑enhanced anti‑CTLA‑4 antibody designed to augment T‑cell priming, deplete intratumoral Tregs, and activate myeloid cells while reducing complement-mediated toxicity; early trials across multiple solid tumors, particularly in combination with balstilimab, have shown encouraging activity including objective responses in MSS colorectal cancer and manageable immune‑related toxicity profiles. Balstilimab is an investigational anti‑PD‑1 antibody that blocks PD‑1/PD‑L1 and PD‑L2 interactions to restore T‑cell effector function; it has demonstrated clinical activity and tolerability alone and in combination with CTLA‑4 blockade in early studies. Arm B (active comparator): standard ipilimumab 1 mg/kg IV plus nivolumab 3 mg/kg IV on Days 1 and 22 for two 6‑week induction cycles, followed by nivolumab 480 mg IV every 4 weeks during seven 12‑week maintenance cycles.
Outcomes: Primary: Objective response rate per RECIST 1.1 comparing botensilimab plus balstilimab versus ipilimumab plus nivolumab. Secondary: Duration of response; 12‑ and 24‑month landmark progression‑free survival; treatment‑free survival including time on/off treatment with grade ≥3 treatment‑related toxicities; safety and tolerability by CTCAE v5.0.
Burden on patient: Moderate. Patients require frequent IV infusions, especially during induction and early maintenance, with visits approximately every 2–3 weeks initially and every 4 weeks during nivolumab maintenance in the control arm or up to weekly‑to‑monthly patterns in the investigational arm’s maintenance cycles. Archival metastatic tumor tissue (10–20 unstained slides or FFPE block) is mandatory and must be shipped by end of Cycle 2; fresh biopsy is not mandated unless archival tissue is insufficient, which could increase burden. Routine safety labs and imaging per RECIST are expected at standard intervals for immunotherapy trials; no intensive pharmacokinetic sampling is described. Travel and time commitments are higher than standard single‑agent therapy but comparable to typical dual‑checkpoint regimens; immune‑related adverse event monitoring may necessitate additional unscheduled visits or interventions.
Last updated: Oct 2025
Inclusion Criteria:
1. Patient must have ECOG PS of ≤ 2 within 28 days of C1D1.
2. Age ≥ 18 years old at the time of informed consent.
3. Patient must have histological confirmation of renal carcinoma with clear cell component including advanced RCC (not amenable to curative surgery or radiation therapy) or metastatic RCC.
4. Patient must have measurable disease by CT or MRI per RECIST 1.1 criteria. Radiated lesions cannot be used as measurable lesions unless there is clear evidence of progression.
5. Patient must have defined IMDC risk categorization of either favorable, intermediate or poor based on clinical variables of increased risk (below).
* No risk factors (0) = favorable risk
* 1-2 risk factors = intermediate risk
* ≥ 3 risk factors = poor risk
NOTE: Patients with all IMDC risk factors are eligible, but will be stratified according to IMDC risk, and initial analysis will be based on the IMDC intermediate and poor risk patients. IMDC Risks:
* KPS less than 80%
* Less than 1 year from diagnosis including original localized disease to randomization(if applicable)
* Hemoglobin less than the lower limit of normal
* Corrected calcium concentration greater than 10 mg/dL
* ANC greater than the ULN
* Platelet count greater than the ULN
6. Patient must have either a formalin-fixed, paraffin-embedded (FFPE) tissue block or at least 10 (preferably 20) unstained tumor tissue sections, obtained from a metastatic lesion, preferably within 3 months or no more than 12 months with an associated pathology report. This tissue must be identified prior to registration. Confirmation of sufficient archival tissue must be obtained after informed consent and the tissue must be shipped to the appropriate lab by end of Cycle 2. Biopsies should be excisional, incisional, or core needle. Fine needle aspiration is unacceptable for submission. Biopsies of bone lesions that do not have a soft tissue component are also unacceptable for submission. This sample is required to be eligible for the trial. If a patient is having a standard of care biopsy, part of that sample may be utilized for eligibility.
7. Demonstrate adequate organ function as defined below; all screening labs to be obtained within 28 days prior to registration.
* Hematological
* White blood cell (WBC) ≥ 2,000/uL
* Absolute Neutrophil Count (ANC) ≥ 1,000/uL; without growth factor support
* Hemoglobin (Hgb) ≥ 8.0 g/dL; ≥ 7 days without PRBC transfusion.
* Platelets ≥ 75,000/uL; without platelet transfusion
* Renal
* Calculated creatinine clearance (CrCl)1 ≥ 40 mL/min
* Hepatic
* Total Bilirubin ≤ 1.5 × upper limit of normal (ULN) \*EXCEPT participants with Gilbert Syndrome who must have a Total Bilirubin level of \< 3.0 x ULN
* Aspartate aminotransferase (AST) ≤ 3.0 × ULN
* Alanine aminotransferase (ALT) ≤ 3.0 × ULN
8. HIV positive patients may be eligible if either:
* Patients with CD4 \> 200 cells/mm3 OR
* Patients with HIV viral load undetectable.
9. Active HBV or active HCV patients may be eligible if:
* Patients with HBV infection are eligible if hepatitis B surface antigen and HBV DNA are negative.
* Patients with HCV infection are eligible if HCV RNA is negative.
10. WOCBP must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic gonadotropin \[HCG\]) within 1 week prior to Cycle 1 Day 1.
11. WOCBP must agree to follow instructions for method(s) of contraception.
12. Males who are sexually active with WOCBP must agree to follow instructions for method(s) of contraception.
Exclusion Criteria:
1. Prior adjuvant or systemic therapy for RCC.
2. Prior treatment with an anti-PD1 or anti-PDL1 agent, anti-CTLA4 antibody or a VEGFR TKI or anti-VEGF antibody including in the adjuvant setting.
3. Radiotherapy within 2 weeks prior to Cycle 1 Day 1.
4. 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).
5. Currently known active and definitive CNS metastases. Patients who have treated brain metastases (with either surgical resection or stereotactic radiosurgery (SRS)) may be eligible. Patients must not have taken any steroids ≤ 2 weeks prior to randomization for the purpose of managing their brain metastases. Repeat imaging after SRS or surgical resection is not required so long as baseline MRI is within 4 weeks of registration. Patients with multiple brain metastases treated with SRS (with or without WBRT), are not excluded. Patients with definitive CNS metastases treated with only WBRT are ineligible. Patients with potential CNS metastases that are too small for treatment with either SRS or surgery (e.g. 1-2 mm) and/or are of uncertain etiology are potentially eligible, but need to be discussed with and approved by the sponsor-investigator.
6. Persistent toxicity of National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 Grade \> 1 severity that is related to prior therapy. NOTE: Sensory neuropathy or alopecia of Grade ≤ 2 are acceptable.
7. Known severe (Grade ≥ 3) hypersensitivity reactions to fully human monoclonal antibodies, antibody, or severe reaction to immuno-oncology agents, such as colitis or pneumonitis requiring treatment with steroids; or has a history of interstitial lung disease, any history of anaphylaxis, or uncontrolled asthma.
8. Known condition requiring systemic treatment with either corticosteroids (\>10 mg daily prednisone or equivalent) or other immunosuppressive medications within 14 days of randomization. Inhaled or topical steroids, and adrenal replacement steroid doses \<10 mg daily prednisone equivalent are permitted in the absence of active autoimmune disease. NOTE: Corticosteroid use as a premedication for IV contrast allergies/reactions is allowed.
9. Active known or suspected autoimmune disease that required systemic treatment within 2 years of the start of study drug (i.e., with use of disease-modifying agents, corticosteroids, or immunosuppressive drugs). Subjects with type I diabetes mellitus, hypothyroidism only requiring hormone replacement, skin disorders (such as vitiligo, psoriasis, or alopecia) not requiring systemic treatment, or conditions not expected to recur in the absence of an external trigger (e.g., celiac disease) are permitted to enroll.
10. Uncontrolled adrenal insufficiency based on investigator discretion.
11. Active infection requiring systemic therapy within 14 days of Cycle 1 Day 1.
12. Clinically significant (i.e., active) cardiovascular disease: cerebral vascular accident/stroke or myocardial infarction within 6 months of enrollment, unstable angina, congestive heart failure (New York Heart Association class ≥ II), or serious uncontrolled cardiac arrhythmia requiring medication.
13. Legally incapacitated or has limited legal capacity.
14. Pregnant or breastfeeding.
15. Prior allogeneic tissue/solid organ transplant, except for corneal transplants.
16. Major surgery (e.g., nephrectomy) less than 28 days prior to Cycle 1 Day 1.
17. Prior malignancy active within the previous 2 years from screening except for locally curable cancers that have been apparently cured, such as basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the prostate, cervix, or breast.
18. Any condition including medical, emotional, psychiatric, or logistical that, in the opinion of the Investigator, would preclude the participant from adhering to the protocol or would increase the risk associated with study participation or study treatment administration or interfere with the interpretation of safety results.
19. Receipt of a live/attenuated vaccine within 30 days of first study treatment. The use of inactivated seasonal influenza vaccines (eg, Fluzone®) will be permitted on study without restriction.
La Jolla, California, 92093, United States
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New Haven, Connecticut, 06520, United States
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Washington D.C., District of Columbia, 20057, United States
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Atlanta, Georgia, 30322, United States
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Indianapolis, Indiana, 46202, United States
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Boston, Massachusetts, 02215, United States
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Boston, Massachusetts, 02215, United States
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Hackensack, New Jersey, 07601, United States
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New York, New York, 10032, United States
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Ithaca, New York, 14850, United States
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Columbus, Ohio, 43210, United States
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Philadelphia, Pennsylvania, 19104, United States
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Dallas, Texas, 75390, United States
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