PRIMARY OBJECTIVES:~I. Dose Escalation Phase (Part 1): To estimate the recommended phase 2 dose (RP2D) of XmAb22841 (CTLA-4 X LAG3) in combination XmAb23104 (PD1 X ICOS).~II. Dose Expansion Phase (Part 2): To assess clinical response as measured by objective response rate of patients treated with XmAb22841 (CTLA-4 X LAG3) in combination XmAb23104 (PD1 X ICOS)~SECONDARY OBJECTIVES:~I. To evaluate the pharmacokinetics (PK) and anti-drug antibody (ADA) immunogenicity of XmAb23104 (PD1 X ICOS) and XmAb22841 (CTLA-4 X LAG3) (Dose Escalation (Part 1) & Dose Expansion (Part 2)).~II. To evaluate the clinical efficacy of XmAb23104 (PD1 X ICOS) and XmAb22841 (CTLA-4 X LAG3) (Dose Expansion (Part 2)).~EXPLORATORY OBJECTIVES:~I. To identify molecular (genomic, metabolic, and/or proteomic) biomarkers that may be indicative of clinical response/resistance, safety, pharmacodynamic activity, and/or the mechanism of action of XmAb22841 (CTLA-4 X LAG3) administered in combination with XmAb23104 (PD1 X ICOS) (Dose Escalation (Part 1) & Dose Expansion(Part 2)).~OUTLINE:~Participants will initially be enrolled in the Dose Escalation Phase (Part 1). Once the recommended phase 2 dose (RP2D) has been established, participants will be enrollment in one of two cohorts in the Dose Expansion Phase (Part 2):~Cohort A: Participants without CNS disease.~Cohort B: Participants with asymptomatic and stable CNS disease~Participants may continue trial therapy until the earlier of radiographic disease progression, withdrawal, unacceptable toxicity, completion of 24 cycles of XmAb23104 (PD1 X ICOS), or other treatment discontinuation due to unacceptable toxicity, participant withdrawal, progressive disease or death. The entire treatment duration of twenty-four 28-day cycles is approximately 2 years. After discontinuing trial therapy, participants will be followed for toxicity, response, and overall survival every 12 weeks for up to 5 years from initiation of study treatment.
This is a first-in-human, multi-center, multi-cohort, open-label, phase Ib/II study of XmAb22841 (CTLA-4 X LAG3) administered in combination with XmAb23104 (PD1 X ICOS) in participants with a histologically or cytologically confirmed diagnosis of an advanced/metastatic melanoma. XmAb22841 (CTLA-4 X LAG3) is a bi-specific antibody targeting two different T cell membrane proteins responsible for regulation of T cell activity. It offers potential immunologic and safety advantages over existing therapies. XmAb22841 (CTLA-4 X LAG3) is being evaluated in this clinical study designed to assess the safety, tolerability, PK, and PD of escalating doses of XmAb22841 (CTLA-4 X LAG3) administered in combination with XmAb23104 (PD1 X ICOS)~The study will be conducted through the University of California Melanoma Consortium (UCMC).