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A phase 1 study of BGB-A3055 (anti-CCR8) with or without tislelizumab (anti-PD-1) in patients with solid tumors
Abstract   Peer reviewed

A phase 1 study of BGB-A3055 (anti-CCR8) with or without tislelizumab (anti-PD-1) in patients with solid tumors

Judith Raimbourg, Martin Gutierrez, Antoine Italiano, Shiraj Sen, Afaf Abed, Jermaine Ian George Coward, Muhammad Furqan, Dingzhi Huang, Rongbo Lin, Pu Sun, …
Journal of clinical oncology, Vol.44(16_suppl), pp.2523-2523
06/01/2026
DOI: 10.1200/JCO.2026.44.16_suppl.2523

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Abstract

2523 Background: BGB-A3055 is a humanized monoclonal antibody targeting C-C motif chemokine receptor 8 (CCR8), a receptor highly expressed on intratumoral regulatory T cells (Tregs). CCR8 overexpression correlates with poor prognosis in certain tumor types. Preclinical studies have shown potent antitumor activity of BGB-A3055. Here, we present results from a phase 1a dose-escalation trial of BGB-A3055 alone (Part A [A]) or combined with tislelizumab (TIS; Part B [B]) in patients (pts) with advanced or metastatic solid tumors (NCT05935098). Methods: Eligible pts had histologically confirmed advanced or metastatic solid tumors with high prevalence of CCR8 expression. In A, pts received BGB-A3055 (six dose levels) intravenously (IV) every 3 weeks (Q3W). In B, pts received BGB-A3055 (six dose levels) and TIS 200 mg IV Q3W. Primary endpoint was safety; secondary endpoints included preliminary antitumor activity (RECIST v1.1). Results: As of Nov 19, 2025, 98 pts were treated with BGB-A3055 ± TIS (A: n=42; B: n=56). Median (range) study follow-up was 3.94 (0.9-19.0) months in A and 4.67 (0.5-16.8) months in B. Treatment-emergent adverse events (TEAEs) are provided in the Table. The most common BGB-A3055-related TEAEs were neutrophil count decreased (23.8%) in A and pyrexia (23.2%) in B. The most common serious TEAE was immune-mediated enterocolitis (A: 4.8%; B: 7.1%). The most common immune-mediated adverse events (imAEs) were rash, rash maculo-papular, and hypothyroidism in A (7.1% each) and rash maculo-papular in B (17.9%). Dose-limiting toxicities occurred in 1 pt in A (immune-mediated hepatitis) and 3 pts in B (colitis, nephrotic syndrome, and rash maculo-papular in a single pt each). No treatment-related TEAEs leading to death were reported. Maximum tolerated dose was not reached. Unconfirmed objective response rate was 7.5% (95% confidence interval [CI]: 1.6-20.4; 3 partial responses [PRs]) in A and 18.2% (95% CI: 9.1-30.9; 1 complete response and 9 PRs) in B. Disease control rate was 35.0% (95% CI: 20.6-51.7) in A and 56.4% (95% CI: 42.3-69.7) in B. Among the 13 responders, 6 received prior immunotherapies. Robust Treg reduction was observed in peripheral blood and tumor tissue post-treatment, indicating potent on-target pharmacodynamic activity of BGB-A3055. Conclusions: BGB-A3055 ± TIS demonstrated a safety profile consistent with selective CCR8 on-target effects in pts with advanced solid tumors and had preliminary antitumor activity. Clinical trial information: NCT05935098. Part ABGB-A3055 monotherapy(n=42)Part BBGB-A3055 + TIS(n=56)Any TEAE, n (%)41 (97.6)55 (98.2)Grade ≥326 (61.9)47 (83.9)Serious17 (40.5)37 (66.1)Leading to death1 (2.4)3 (5.4)Leading to treatment discontinuation9 (21.4)23 (41.1)Any BGB-A3055-related TEAE, n (%)35 (83.3)53 (94.6)Grade ≥318 (42.9)31 (55.4)Serious5 (11.9)20 (35.7)Any imAE, n (%)15 (35.7)33 (58.9)

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