On December 10, 2025 NovaBridge Biosciences (Nasdaq: NBP) (NovaBridge or the Company) a global biotechnology platform company committed to accelerating access to innovative medicines, reported the presentation of new data from the expanded 3mg/kg every 6 week (Q6W) Phase 1 dosing study for ragistomig, a bispecific 4-1BB X PD-L1 antibody, in a poster at the European Society for Medical Oncology – Immuno-Oncology Congress 2025 (ESMO-IO 2025) by co-developer ABL Bio. The poster (Poster 257P), presented by Gerald Falchook, MD, Director of the Sarah Cannon Research Institute (SCRI) at HealthONE Denver, showed the new Q6W schedule demonstrated consistent monotherapy antitumor activity with improved immunological endpoints and tolerability.
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"We are very pleased by the impressive ragistomig Phase 1 dose expansion data presented today at ESMO (Free ESMO Whitepaper)-IO, indicating that the prior Q2W schedule demonstrated meaningful clinical activity, and that the new Q6W dosing interval provides comparable efficacy with a more favorable safety profile. The study achieved its objective by extending the therapeutic window and supports the advancement of ragistomig into combination studies. We are particularly encouraged by the improved safety profile, with only 5% of patients experiencing ≥ Grade 3 liver function elevation, while maintaining comparable immune-mediated activity. These observations, combined with comparable confirmed responses and durable immune engagement, underpins our optimism that ragistomig has the potential to make an important contribution to more effective treatment outcomes for patients with relapsed/refractory solid tumor cancers," said Phillip Dennis, MD, PhD, Chief Medical Officer of NovaBridge.
"Ragistomig was designed to overcome resistance in patients who relapsed after treatment with checkpoint inhibitors, a multi-billion dollar pillar of cancer treatment. The ragistomig data presented at ESMO (Free ESMO Whitepaper)-IO build on the promising results presented at ASCO (Free ASCO Whitepaper) 2024. This program aligns well with our strategy to partner with innovators around the world to advance transformative and potentially breakthrough therapies. We are enthusiastic to collaborate with our partner, ABL Bio, to initiate combination studies," said Sean Fu, PhD, Chief Executive Officer of NovaBridge.
ESMO-IO Meeting information:
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Title: Phase 1 Clinical Trial of Ragistomig (ABL503/TJ-L14B: PD-L1 × 4-1BB bispecific antibody) Q6W Dosing Balances Favorable Safety and Sustained Efficacy Through Extended Immunologic Memory and Reinvigoration of CD8+ T Cells
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Abstract #688/Poster 257P
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Date and Time: Wednesday, December 10th at 5:15 PM GMT
A copy of the poster will be available here after the session. To review an overview of the Phase 1 dose escalation data, click here.
Ragistomig Phase 1 Monotherapy Q6W Data (per October 22, 2025 data cut-off):
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Ragistomig demonstrated comparable anti-tumor efficacy for the Q6W dose schedule compared to the Q2W regimen (58.8% disease control rate (DCR) at Q6W compared to 64.3% at Q2W)
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Ragistomig exhibited a favorable and improved safety profile, with 1/20 Grade ≥3 liver function test elevations (LFT), no treatment discontinuations due to treatment emergent adverse events (TEAEs) and no reported cytokine release syndrome (CRS)
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Overall immune cell activity was consistent between the Q6W and Q2W dosing. Immune cell pharmacodynamics with the Q6W dosing demonstrated expansion of effector memory and CD8+ T cells, with attenuated Treg expansion, indicating durable immune engagement
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The data suggest evaluation of the ongoing 5 mg/kg Q6W dosing cohort and evaluation of ragistomig in future combination studies
Patient Characteristics:
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20 heavily pre-treated subjects received 3 mg/kg Q6W ragistomig. In this group, 100% were previously treated with immuno-oncology therapies and 70% had previously received ≥3 lines of systemic treatment and exhausted all available standard treatment options
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Dosing is underway in 10 patients who are receiving 5 mg/kg Q6W ragistomig
Efficacy Results, based on 17 evaluable patients receiving 3 mg/kg Q6W v. 14 evaluable patients with 3 mg/kg Q2W
ABL503 monotherapy
efficacy profiile
3 mgkg Q6W
(N=17)
3 mg/kg Q2W
(N=14)
Objective Response Rate, n (%)
2 (11.8%)
4 (28.6%)
Disease Control Rate, n (%)
10 (58.8%)
9 (64.3%)
Complete response
0 (0%)
1 (7.1%)
Partial response
2 (11.8%)
3 (21.4%)
Stable disease
8 (47.1%)
5 (35.7%)
Progressive disease
7 (41.2%)
5 (35.7%)
Safety Data, based on 20 evaluable patients receiving 3 mg/kg Q6W v. 15 evaluable patients with 3 mg/kg Q2W
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An improved safety profile was observed with the 3 mg/kg Q6W regimen
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The 3 mg/kg Q6W regimen was identified as an optimal potential regimen for combination strategies
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1/20 subjects (5%) experienced ≥Grade 3 LFT elevation at Q6W dosing v. 40% at Q2W dosing
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TEAEs ≥Grade 3 were 50% at the Q6W (10/20) v. 66.7% (10/15) at 3 mg/kg Q2W. In the Q6W dose, these TEAEs, including LFT elevations, decreased platelet count, anemia and decreased neutrophil count, were recovered within 3-14 days (with or without treatment interventions), with no discontinuations
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No cases of CRS were reported with either dosing schedule
Immunology Data:
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Effector and memory CD8+ T cell subsets were increased, with comparable fold-changes between dosing groups, suggesting that immune mediated pharmacodynamic activity may contribute to efficacy
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CTLA+ Treg frequencies remained near baseline in the Q6W group, suggesting a more favorable effector-to-regulatory balance
About Ragistomig
Ragistomig (also known as ABL503) is a differentiated novel bispecific that integrates a single-chain, Fc-silent PD-L1 segment as a tumor engager and 4-1BB segment as a conditional T cell activator. It was developed using ABL Bio’s "Grabody-T" bispecific antibody platform technology to overcome resistance to PD-(L)1 inhibition and stimulate 4-1BB activation only in the presence of PD-L1 expressing tumor cells, to minimize the risk of off-tumor toxicity. Preclinical studies demonstrated that the bispecific antibody showed better anti-tumor activity than its single-agent components. A Phase 1 dose expansion study (NCT04762641) is currently being conducted in the U.S. and South Korea. The study was designed with a primary endpoint of defining the dose-limiting toxicity and adverse event profile of ragistomig, as well as to observe the objective response rate, pharmacokinetic and immunogenicity profiles and other secondary endpoints.
Ragistomig (also known as ABL503) is being jointly developed with ABL Bio
ASCO 2024: the 2024 American Society for Clinical Oncology Annual Meeting; Q6W: every six weeks
(Press release, NovaBridge Biosciences, DEC 10, 2025, View Source [SID1234661348])