GigaGen reports early Phase 1 data for GIGA-564, a novel anti-CTLA-4 antibody, showing favorable safety and initial anti-tumor activity in advanced solid tumors at AACR 2026.
Written By: Vennela Reddy, BPharm
Reviewed By: Pharmacally Editorial Team
GigaGen Inc., a subsidiary of Grifols, presented early Phase 1 data for its investigational anti-CTLA-4 monoclonal antibody GIGA-564 at the American Association for Cancer Research Annual Meeting 2026 in San Diego. The first-in-human, open-label study enrolled 26 patients with advanced or metastatic solid tumors, with 22 evaluable for response.
GIGA-564 demonstrated a favorable safety and tolerability profile, with only one dose-limiting toxicity reported and no maximum tolerated dose reached during escalation up to 20 mg/kg administered every three weeks. Preliminary efficacy findings showed two patients achieving partial responses and nine patients with stable disease, including two with minor tumor reductions, resulting in a disease control rate of 50%. Early anti-tumor activity was observed in both anti-PD-1 refractory and immunotherapy-naïve patients.
GIGA-564 is a fully human monoclonal antibody designed with a differentiated mechanism that targets CTLA-4 without blocking its interaction with ligands. This approach enables selective depletion of regulatory T cells within the tumor microenvironment, potentially enhancing localized anti-tumor immune responses while limiting systemic immune-related toxicities associated with conventional CTLA-4 inhibitors.
According to James Gulley of the National Cancer Institute, the combination of a favorable safety profile and early signs of anti-tumor activity is notable at this stage, particularly in heavily pretreated and treatment-naïve populations, supporting further evaluation in refractory cancers.
Carter Keller of GigaGen highlighted the ongoing unmet need in solid tumors and noted that the early findings indicate potential to improve patient outcomes. The trial, conducted by the NCI in collaboration with GigaGen (NCT06258304), remains ongoing to further assess safety, dosing, and clinical activity.
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About the Writer
Vennela Reddy, B.Pharm is a pharmacy graduate with a keen interest in clinical research, pharmacovigilance, and medical writing, with a growing focus on publishable and scientific content development. In her words, she is passionate about translating complex medical data into clear, evidence-based communication.