Sponsor: Benjamin Spieler (other)
Phase: 2
Start date: June 18, 2025
Planned enrollment: 20
Balstilimab (AGEN2034; BAL) is an investigational, fully human IgG4 monoclonal antibody targeting programmed cell death protein 1 (PD-1). It has been studied as monotherapy and in combinations—particularly with the CTLA-4 inhibitors zalifrelimab and botensilimab—in cervical, colorectal and other solid tumors. It is not FDA-approved; a biologics license application for recurrent/metastatic cervical cancer was voluntarily withdrawn in 2021 after the FDA recommended against pursuing accelerated approval following full approval of pembrolizumab in the same setting. (investor.agenusbio.com)
Balstilimab binds PD-1 and blocks its interaction with PD-L1 and PD-L2, preventing inhibitory PD-1 signaling and potentially restoring cytotoxic T-cell activity against tumors. (cancer.gov)
Cervical cancer monotherapy: In a single-arm phase I/II study, 140 efficacy-evaluable patients with previously treated recurrent or metastatic cervical cancer received balstilimab 3 mg/kg every two weeks. The confirmed objective response rate (ORR) was 15.0% (95% CI, 10.0–21.8%), including 3.6% complete responses and 11.4% partial responses. The disease-control rate was 49.3%, and median response duration was 15.4 months. ORR was 20.0% in PD-L1-positive and 7.9% in PD-L1-negative disease. (pmc.ncbi.nlm.nih.gov)
Randomized cervical-cancer study: In the phase II RaPiDS trial, investigator-assessed ORR was 24% with balstilimab–zalifrelimab and 15% with balstilimab–placebo; blinded independent review found ORRs of 24% and 26%, respectively. Because the study was non-comparative and the investigator and independent assessments differed, it did not establish that adding zalifrelimab improved efficacy. (annalsofoncology.org)
Colorectal cancer combination: In a peer-reviewed phase I study of 101 response-evaluable patients with heavily pretreated, microsatellite-stable metastatic colorectal cancer, botensilimab plus balstilimab produced a 17% ORR (95% CI, 10–26%) and 61% disease-control rate. Median response duration was not reached and median progression-free survival was 3.5 months. These results apply to the combination and do not isolate balstilimab’s contribution. (pubmed.ncbi.nlm.nih.gov)
With cervical-cancer monotherapy, 71.4% of patients experienced treatment-related adverse events; commonly reported events included asthenia and diarrhea. The most frequent grade ≥3 treatment-related events were immune-mediated enterocolitis (3.1%) and diarrhea (1.9%). (pmc.ncbi.nlm.nih.gov)
In RaPiDS, treatment-related adverse events occurred in 71% of patients receiving balstilimab–zalifrelimab and 64% receiving balstilimab–placebo; grade 3 events occurred in 23% and 15%, respectively. No treatment-related deaths were reported. (annalsofoncology.org)
With botensilimab–balstilimab in metastatic colorectal cancer, 89% experienced treatment-related adverse events, most commonly fatigue (35%), diarrhea (32%) and fever (24%). Twelve percent discontinued because of treatment-related toxicity, and no grade 5 treatment-related events occurred. (pubmed.ncbi.nlm.nih.gov)
Last updated: Sep 2026
Botensilimab (AGEN1181; BOT) is an investigational, fully human, Fc-engineered IgG1 monoclonal antibody targeting CTLA-4. It is being studied both alone and—more commonly—in combination with the investigational anti-PD-1 antibody balstilimab. Clinical development includes colorectal, ovarian, liver and other difficult-to-treat solid tumors. Evidence remains preliminary because most results come from small, non-randomized phase 1–2 studies; a randomized phase 2 colorectal-cancer trial is ongoing and has not posted results. (cancer.gov)
Botensilimab blocks CTLA-4-mediated suppression of T-cell activation. Its engineered Fc region has increased affinity for activating Fcγ receptors on antigen-presenting and natural-killer cells. Preclinical and translational studies indicate that this design may strengthen T-cell priming and memory, activate innate immunity, and promote depletion of intratumoral regulatory T cells. Whether these properties produce better clinical outcomes than established CTLA-4 antibodies has not yet been demonstrated in randomized trials. (pmc.ncbi.nlm.nih.gov)
The most extensive published evidence is for botensilimab plus balstilimab:
Toxicity resembles that expected from CTLA-4/PD-1 checkpoint inhibition, particularly immune-mediated gastrointestinal and hepatic events. In the 148-patient metastatic colorectal-cancer safety population, 89% experienced a treatment-related adverse event; 31% had grade 3 and 1% had grade 4 events. Common events included fatigue (35%), diarrhea (32%) and fever (24%). Immune-mediated diarrhea/colitis occurred in 33%, including grade 3–4 events in approximately 11%. Twelve percent discontinued both drugs because of toxicity, and no treatment-related deaths were reported. (pmc.ncbi.nlm.nih.gov)
Last updated: Sep 2026
Goal: Assess whether stereotactic body radiation therapy (SBRT) followed by dual checkpoint inhibition provides clinical benefit in previously treated metastatic pancreatic ductal adenocarcinoma (PDAC).
Patients: Adults with microsatellite-stable metastatic PDAC, measurable disease, progression after at least one systemic therapy, ECOG performance status 0–1, and at least one previously unirradiated lesion suitable for biopsy. Liver tumor burden must not exceed 25%; key exclusions include active untreated CNS metastases, clinically significant autoimmune disease, and prior liver-directed radiation or embolization.
Design: Single-arm, nonrandomized phase 2 treatment study; there is no comparator group.
Treatments: Participants receive SBRT, then botensilimab for up to 24 weeks in combination with balstilimab for up to one year. Botensilimab is an investigational, Fc-engineered anti-CTLA-4 antibody designed to enhance T-cell activation and intratumoral immune activity. Balstilimab is an investigational anti-PD-1 antibody that blocks inhibitory PD-1 signaling. In a single-arm study of previously treated microsatellite-stable metastatic colorectal cancer, the combination produced a 17% objective response rate; efficacy in metastatic PDAC remains unproven.
Outcomes: The primary endpoint is clinical benefit rate—complete response, partial response, or stable disease by iRECIST—assessed through 15 months. Secondary endpoints are confirmed objective response rate, progression-free survival, overall survival, and the number of participants with grade 3 or higher toxicities.
Burden on patient: Moderate to high. Participation requires a pretreatment tumor biopsy, a course of SBRT, and repeated immunotherapy visits for up to one year, along with response imaging and toxicity monitoring. Follow-up may extend to five years; the visit frequency and any additional research sampling are not specified.
Last updated: Sep 2026
Inclusion Criteria:
1. ≥18 years old
2. Histologically or cytologically confirmed diagnosis of pancreatic ductal adenocarcinoma.
3. Microsatellite stable (MSS) disease by pathologic assessment.
4. Patients must have measurable disease as defined by RECIST 1.1.
5. Progression on ≥1 line of systemic therapy.
6. No concomitant therapy with any of the following: interleukin (IL)-2, interferon, non study immunotherapy regimens, cytotoxic chemotherapy, immunosuppressive agents, other investigational therapies, and/or chronic use of systemic corticosteroids.
7. No known infection with human immunodeficiency virus (HIV) or active infection with Hepatitis B.
8. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1.
9. Life expectancy ≥3 months.
10. Patients must have the following lab values obtained \<4 weeks prior to starting protocol treatment:
1. absolute neutrophil count (ANC) ≥1,000 cells/μL
2. white blood count (WBC) ≥2,000 cells/μL
3. platelets ≥75,000 per μL
4. hemoglobin ≥8.0 g/dL
5. creatinine clearance ≥40 mL/min)
6. serum total bilirubin ≤ 1.5 times the upper limit of normal (ULN)
7. aspartate aminotransferase (AST) and alanine transaminase (ALT) ≤3 × ULN (or ≤5 × ULN in patients with liver metastases)
8. international normalized ratio or prothrombin time ≤1.5 × ULN
9. activated partial thromboplastin time ≤2.5 × ULN
10. absolute lymphocyte count (ALC) ≥1000 cells/μL at baseline
11. At least 1 previously unirradiated lesion amenable to pre-treatment biopsy.
12. No limit on overall numbers of lesions, but liver tumor burden ≤25% of total liver volume.
13. Women of childbearing potential (WOCBP): negative serum pregnancy test (within 7 days prior to Day 1 of protocol therapy)
a. Females of non-childbearing potential are defined as: i. ≥ 50 years of age and has not had menses for greater than 1 year ii. 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 iii. Status is post-hysterectomy, bilateral oophorectomy, or tubal ligation.
14. Male and female patients of reproductive potential must use effective methods of contraception or abstain from sexual activity for the course of the study through at least 6 months after the last dose of balstilimab and/or botensilimab. See Section 4.11, Contraception.
Exclusion Criteria:
1. Liver tumor burden exceeding 25% of total liver volume.
2. Active, untreated central nervous system (CNS) metastases.
3. Active autoimmune disease or history of autoimmune disease that required systemic treatment within 2 years of the start of study treatment (i.e., with use of disease-modifying agents or immunosuppressive drugs).
4. Participants with a condition requiring systemic treatment with either corticosteroids (\> 10 mg daily prednisone equivalent) within 14 days or another immunosuppressive medication within 30 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.
5. Previous external beam radiation therapy to the liver or radioisotope therapy directed to the liver or any liver embolization.
6. Clinically significant ascites requiring a paracentesis in the last 4 weeks, or clinically significant history of liver failure defined as any prior episode of hepatic encephalopathy and/or any prior history of an elevated serum ammonia level.
7. Partial or complete bowel obstruction within the last 3 months prior to study enrollment, signs/symptoms of bowel obstruction, or known radiologic evidence of impending obstruction.
8. Clinically significant (i.e., active) cardiovascular disease: cerebral vascular accident/stroke or myocardial infarction within 6 months of study enrollment, unstable angina, congestive heart failure (New York Heart Association class ≥ III), or serious uncontrolled cardiac arrhythmia requiring medication.
a. QT interval corrected using Fridericia's formula (QTcF) of \> 480 ms.
9. Prior allogeneic organ transplantation.
10. Treatment with chemotherapy or targeted therapy within 2 weeks prior to initiating EMPIRE treatment.
11. Persistent grade ≥2 adverse events (aEs) from prior therapy (except neuropathy).
12. Known additional malignancy requiring active treatment.
13. History of non-infectious pneumonitis.
14. Active infection requiring antibiotic.
15. Live vaccine within 30 days of protocol treatment.
16. Severe acute respiratory syndrome (SARS) coronavirus 2 (CoV 2) (SARS-CoV-2) vaccine or booster \< 7 days before Cycle 1 Day 1 (C1D1). For vaccines requiring more than 1 dose, the full series should be completed prior to C1D1, when feasible. Booster shot not required but also must be administered \> 7 days from C1D1 or \> 7 days from future cycle on study.
17. History of severe hypersensitivity reaction to monoclonal antibody.
18. Participants with impaired decision-making capacity.
Miami, Florida, 33136, United States
[email protected] / 305-243-4229
Status: Recruiting