Sponsor: Michael B. Atkins, MD (other)
Phase: 2
Start date: Sept. 25, 2023
Planned enrollment: 120
Balstilimab (AGEN2034, BAL) is a fully human monoclonal IgG4 antibody that binds with high affinity to programmed death 1 (PD-1), preventing its interaction with PD-L1 and PD-L2 ligands. The drug is designed to enhance T cell activation and effector function [1]. It is being developed by Agenus Inc. as both a monotherapy and in combination with other immunotherapy agents, particularly botensilimab (an anti-CTLA-4 antibody).
As a monotherapy, balstilimab showed activity in a phase II trial for recurrent/metastatic cervical cancer, with an objective response rate (ORR) of 15% and median duration of response of 15.4 months. In PD-L1 positive patients with squamous cell carcinoma, the ORR was 21%. The drug also showed some activity in PD-L1 negative patients [2]. When combined with zalifrelimab (anti-CTLA-4), the ORR increased to 25.6% in cervical cancer patients, with a disease control rate of 52% [3].
The safety profile appears manageable based on clinical trials. In combination therapy with zalifrelimab for cervical cancer, the most common treatment-related adverse events were hypothyroidism (16.8%), diarrhea (14.2%), fatigue (11.6%), and nausea (9.0%) [3]. Development history includes a withdrawn BLA for cervical cancer in 2021, but the drug continues to be studied in various combinations and indications, particularly with botensilimab in colorectal cancer and other solid tumors [4].
[1] Phase II Trial Results in Journal of Clinical Oncology [2] Clinical Trial Results in Gynecologic Oncology [3] Phase II Combination Trial Results in Journal of Clinical Oncology [4] Recent Development Update from BioSpace
Last updated: Dec 2024
Botensilimab is an investigational Fc-enhanced anti-CTLA-4 monoclonal antibody being developed by Agenus Inc. for cancer immunotherapy. It is designed to boost both innate and adaptive anti-tumor immune responses through multiple mechanisms: enhanced T cell priming and activation, depletion of regulatory T cells (Tregs) in the tumor microenvironment, activation of myeloid cells, and induction of long-term memory responses [1]. The drug's novel Fc-enhanced design allows it to bind more effectively to both high and low-affinity FcγRIIIA variants, potentially extending its benefits to a broader patient population compared to first-generation CTLA-4 inhibitors. Additionally, botensilimab is engineered to reduce complement-mediated toxicity through reduced C1q binding [2].
The drug has shown promising results in clinical trials, particularly in combination with the PD-1 inhibitor balstilimab. In a phase 1 trial of patients with microsatellite stable (MSS) metastatic colorectal cancer without liver metastases, the combination achieved a 23% objective response rate with a median overall survival of 21.2 months [3]. More recently, in the neoadjuvant NEST-1 trial for resectable colorectal cancer, the combination showed impressive pathologic response rates, with tumor shrinkage of ≥50% observed in 67.5% of MSS CRC patients [4]. The drug has demonstrated clinical responses across nine different types of metastatic, late-line cancers, including traditionally immunotherapy-resistant tumors.
The safety profile of botensilimab appears manageable based on clinical trial data. In the phase 1 trial combining botensilimab with balstilimab, the most common treatment-related adverse events were diarrhea/colitis, fatigue, and decreased appetite. Grade 3-4 adverse events occurred in approximately 39% of patients, with diarrhea/colitis being the most frequent serious adverse event. Notably, unlike some other CTLA-4 inhibitors, no cases of hypophysitis were reported in the monotherapy arm, which may be attributed to the drug's reduced complement activation [2]. As of 2024, approximately 1100 patients have been treated with botensilimab in phase 1 and phase 2 clinical trials.
[1] Cancer Discovery Article on Botensilimab Mechanism and Clinical Results [2] OncoDaily Detailed Review of Botensilimab [3] Phase 1 Trial Results in OncoLive [4] NEST-1 Trial Results Press Release
Last updated: Dec 2024
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, while characterizing durability of benefit and safety.
Patients: Adults (≥18 years) with histologically confirmed clear cell RCC that is unresectable or metastatic, treatment naïve in the systemic/adjuvant setting, ECOG PS 0–2, measurable disease by RECIST 1.1, and adequate organ function. All IMDC risk groups are eligible with stratification by risk; initial efficacy analyses focus on intermediate/poor risk. Controlled HIV, resolved HBV/HCV viremia, and treated brain metastases under specified conditions are permitted. Key exclusions include prior ICI or VEGF/VEGFR therapies, uncontrolled autoimmune disease or need for significant immunosuppression, recent major surgery, active serious infection, and unstable cardiovascular disease.
Design: Randomized, open-label, multicenter phase 2 trial using a Simon two-stage design; 120 patients randomized 2:1 to experimental versus control. Treatment continues until toxicity, progression, or a maximum of 96 weeks (12-week induction, 84-week maintenance).
Treatments: Arm A: 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 alone on Days 1 and 22. Maintenance: Cycles 3–4 botensilimab 75 mg IV Day 1 plus balstilimab 450 mg IV on Days 1, 22, 43, 64; Cycles 5–9 balstilimab 450 mg IV alone on Days 1, 22, 43, 64. Botensilimab is an Fc‑enhanced anti‑CTLA‑4 antibody designed to augment T‑cell priming and Treg depletion, activate myeloid cells, and induce immune memory; Fc engineering increases engagement of FcγRIIIa with reduced C1q binding to potentially mitigate complement‑mediated toxicity. In early trials, botensilimab with balstilimab has shown activity across multiple solid tumors, including a 23% ORR and prolonged survival in MSS colorectal cancer subsets, with a manageable immune‑related toxicity profile dominated by diarrhea/colitis and fatigue. Balstilimab is a human IgG4 PD‑1 inhibitor that restores T‑cell effector function; it has demonstrated antitumor activity as monotherapy and enhanced responses in combination with CTLA‑4 blockade in cervical cancer studies. Arm B: 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; this is an established first‑line regimen in metastatic ccRCC.
Outcomes: Primary: Objective response rate by RECIST 1.1 comparing experimental versus control arms. Secondary: Duration of response, 12- and 24-month landmark progression-free survival, treatment-free survival (including time on/off therapy and time with grade ≥3 treatment-related toxicities), and safety per CTCAE v5.0.
Burden on patient: Moderate. Patients must provide archival metastatic tumor tissue (10–20 unstained slides or FFPE block) by end of Cycle 2, which may require coordination and shipping but not necessarily a new biopsy unless archival tissue is insufficient. Visit frequency is higher than standard due to induction dosing on Days 1 and 22 and maintenance dosing every 2–4 weeks depending on cycle, necessitating regular travel for infusions over up to 96 weeks. Routine safety labs, imaging for RECIST assessments at typical intervals, and management of potential immune-related adverse events add clinical monitoring demands similar to other ICI trials. No intensive pharmacokinetic sampling or mandated on‑study biopsies are specified, mitigating additional procedural burden.
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.
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