Sponsor: Brian Rini (other)
Phase: 2
Start date: Sept. 23, 2025
Planned enrollment: 120
Fianlimab (REGN3767) is an investigational, fully human monoclonal antibody targeting LAG-3 being developed primarily in combination with the PD‑1 inhibitor cemiplimab for melanoma and other solid tumors. Multiple phase 3 trials are ongoing in advanced and adjuvant melanoma and in first-line non–small cell lung cancer (NSCLC); no phase 3 efficacy results have been reported as of October 7, 2025. (ascopubs.org)
Advanced melanoma (phase 1, multicohort; fianlimab 1600 mg Q3W + cemiplimab 350 mg Q3W) - PD‑1–naïve advanced disease: ORR 63% in two independent cohorts (n=40 each); combined across three cohorts without prior anti‑PD‑1 for advanced disease (n=98), ORR 61.2% with median PFS 13.3 months (95% CI, 7.5–NE). CR rates were 12–15% across PD‑1–naïve cohorts. (ascopubs.org) - Prior anti‑PD‑1 in the adjuvant setting (relapse after adjuvant therapy; n=13 within a cohort of n=18): ORR 61.5% and median PFS 12 months (95% CI, 1.4–NE). (ascopubs.org) - Prior anti‑PD‑1 for advanced disease (n=15): ORR 13.3% and median PFS 1.5 months (95% CI, 1.3–7.7). (ascopubs.org) - Post hoc/independent review updates: In a combined analysis of PD‑1–naïve cohorts (n=98) with longer follow‑up, ORR 57% by BICR (CR 25%, PR 33%) was reported, with activity observed irrespective of baseline LAG‑3 or PD‑L1 expression. (onclive.com)
Ongoing phase 3 melanoma trials (no results yet) - First‑line unresectable/metastatic melanoma: fianlimab + cemiplimab versus pembrolizumab; primary endpoint PFS; estimated sample size ~1,500+. (ascopubs.org) - Adjuvant high‑risk resected melanoma: fianlimab + cemiplimab versus pembrolizumab (double‑blind, three‑arm design). (ascopubs.org) - Additional phase 3 head‑to‑head versus relatlimab+nivolumab is enrolling. (yalemedicine.org)
NSCLC (ongoing; no results yet) - Two randomized phase 2/3 trials: (1) PD‑L1 ≥50% tumors—fianlimab + cemiplimab versus cemiplimab; (2) all‑comers with chemotherapy—fianlimab + cemiplimab + chemotherapy versus cemiplimab + chemotherapy. (ascopubs.org)
Across the melanoma phase 1 cohorts of fianlimab + cemiplimab: - Grade ≥3 treatment‑emergent AEs occurred in 44% of patients; grade ≥3 treatment‑related AEs in 22%. An increased incidence of adrenal insufficiency was noted (any‑grade 12%, grade 3–4 4%) relative to typical PD‑1 monotherapy experience; otherwise, the safety profile was broadly comparable to PD‑1 inhibitors. Common AEs included fatigue and rash. (ascopubs.org)
Notes: Efficacy figures above derive from early‑phase studies; confirmatory phase 3 outcomes are pending as of October 7, 2025. (ascopubs.org)
Last updated: Oct 2025
Goal: To compare antitumor activity and safety of dual checkpoint blockade with fianlimab plus cemiplimab, with or without ipilimumab, versus standard ipilimumab plus nivolumab as first-line therapy for advanced clear cell renal cell carcinoma.
Patients: Adults (≥18 years) with advanced (not amenable to curative surgery or radiotherapy) or metastatic AJCC stage IV renal cell carcinoma with a clear cell component, measurable disease by RECIST 1.1, Karnofsky performance status ≥70%, adequate organ function, and no prior systemic therapy for RCC (including no prior neo/adjuvant systemic therapy). All IMDC risk groups are eligible. Key exclusions include need for chronic immunosuppression (≥10 mg prednisone equivalent/day), recent/active autoimmune disease requiring systemic therapy, history of myocarditis, CNS metastases as defined by protocol, active infection requiring systemic therapy, pregnancy/breastfeeding, and recent live attenuated vaccination.
Design: Randomized, open-label, three-arm phase 2 trial with planned enrollment of 120 patients. Randomization is 2:2:1 to Arm A (triplet), Arm B (doublet), or Arm C (active comparator), with follow-up for efficacy and safety endpoints extending up to 5 years.
Treatments: Arm A investigates IV fianlimab plus IV cemiplimab combined with IV ipilimumab. Arm B investigates IV fianlimab plus IV cemiplimab. Arm C is the standard active comparator of IV ipilimumab plus IV nivolumab, with nivolumab continued after the combination phase per usual approach. Fianlimab is a fully human IgG4 anti–LAG-3 monoclonal antibody designed to relieve LAG-3–mediated T-cell inhibition and augment antitumor immunity; it is being paired with PD-1 blockade (cemiplimab) to enhance T-cell activation through complementary checkpoint pathways. The most mature clinical experience has been in advanced melanoma, where fianlimab plus cemiplimab produced objective responses in roughly 6 of 10 anti–PD-1–naïve patients and a median PFS on the order of a year; activity was substantially lower in patients previously treated with anti–PD-1 for advanced disease. Reported safety has generally resembled PD-1–based therapy, with notable immune-related events including a higher-than-typical incidence of adrenal insufficiency, underscoring the need for endocrine monitoring.
Outcomes: The primary endpoint is objective response rate (confirmed CR+PR by RECIST 1.1) assessed over 2 years. Secondary endpoints include median PFS, 12- and 24-month PFS rates, duration of response, treatment-free survival (including characterization of time on/off therapy and time with grade ≥3 treatment-related toxicity), and treatment-related adverse event and serious adverse event rates graded by CTCAE v5 over up to 5 years.
Burden on patient: Moderate. Treatment is entirely intravenous across all arms, requiring frequent infusion visits similar to standard immune checkpoint regimens in metastatic RCC. Imaging and response assessments by RECIST 1.1 over a prolonged follow-up period add ongoing visit and scan requirements, but these are broadly consistent with routine practice for first-line metastatic RCC trials. A mandatory provision of archival tumor tissue (preferably recent and from a metastatic site) is required; this may necessitate an additional biopsy if adequate tissue is not available, increasing burden for some patients. No intensive phase 1–style pharmacokinetic sampling is described, and safety monitoring is typical for multi-agent immunotherapy (laboratory monitoring and vigilance for immune-related toxicities, including endocrine events).
Last updated: Feb 2026
Inclusion Criteria:
1. Signed informed consent and HIPAA authorization for release of personal health information prior to registration. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.
2. Age ≥ 18 years at the time of consent.
3. Karnofsky Performance Status ≥ 70% within 14 days prior to registration.
4. Histological or cytological evidence of renal cell carcinoma having a clear cell component
5. Advanced (not amenable to curative surgery or radiation therapy) or metastatic (AJCC Stage IV \[version 9\]) renal cell carcinoma.
6. Treatment naïve for systemic therapy for renal cell carcinoma including no prior neo/adjuvant systemic therapy
7. Measurable disease according to RECIST 1.1 within 28 days prior to registration.
8. Patient must have either a formalin-fixed, paraffin-embedded (FFPE) tissue block or unstained tumor tissue sections, obtained from preferably a metastatic lesion, preferably within 3 months or no more than 12 months with an associated pathology report. If the metastatic lesion biopsy specimen does not contain at least 20 unstained slides, supplementation with primary kidney cancer tissue is acceptable.
9. Demonstrate adequate organ function as defined in the protocol. All screening labs to be obtained within 14 days prior to registration.
10. Females of childbearing potential must have a negative serum pregnancy test within 14 days prior to registration.
11. Females of childbearing potential who are sexually active with a male able to father a child must be willing to abstain from penile-vaginal intercourse or must use an effective method(s) of contraception. Males able to father a child who are sexually active with a female of childbearing potential must be willing to abstain from penile-vaginal intercourse or use an effective method(s) of contraception.
12. Known HIV-infected subjects on effective anti-retroviral therapy with undetectable viral load and CD4 count above 350 either spontaneously or on a stable antiviral regimen within 6 months of registration are eligible for this trial. Testing is not required at screening unless mandated by local policy
13. Subjects with known chronic hepatitis B virus (HBV) infection, must have an undetectable HBV viral load (serum hepatitis B virus DNA PCR that is below the limit of detection) and be on suppressive therapy, if indicated.
14. Subjects with a history of hepatitis C virus (HCV) infection must have been treated and cured (undetectable HCV RNA by PCR either spontaneously or in response to a successful prior course of anti-HCV therapy). For subjects with HCV infection who are currently on treatment, the HCV viral load must be undetectable to be eligible for this trial. Testing is not required at screening unless mandated by local policy.
15. As determined by the enrolling physician or protocol designee, ability of the subject to understand and comply with study procedures for the entire length of the study.
Exclusion Criteria:
1. Prior systemic therapy against renal cell carcinoma in the neo/adjuvant or metastatic setting
2. Any condition requiring ongoing ≥ 10 mg prednisone equivalent/day
3. Participants with a history of myocarditis.
4. If clinically indicated based on clinical assessment and any ECG abnormalities, optional troponin T (TnT) or troponin I (TnI) may be done as described in the protocol.
5. Ongoing or recent (within 2 years) evidence of an autoimmune disease that required systemic treatment with immunosuppressive agents. The following are allowed: vitiligo, childhood asthma that has resolved, residual hypothyroidism that requires only hormone replacement, psoriasis not requiring systemic treatment.
6. Central nervous system (CNS) metastases as described in the protocol.
7. Active infection requiring systemic therapy as described in the protocol.
8. Pregnant or breastfeeding as described in the protocol.
9. Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen, per treating physician discretion.
10. Subjects must not receive live attenuated vaccines within 4 weeks prior to Cycle 1 Day 1 or at any time during the study. Inactivated vaccines are allowed.
11. Known hypersensitivity to the active substances or to any of the excipients.
12. Currently participating in another study or participated in any study of an investigational agent or investigational device within 30 days of the first dose of study drug.
Nashville, Tennessee, 37232, United States
[email protected] / 615-343-6584
Status: Recruiting