Triple-Negative Breast Cancer with Brain Metastases: 77% Response with Adebrelimab, Bevacizumab, and Platinum

The phase-2 study presented at the ASCO 2025 meeting, the ABC trial, in patients with triple-negative breast cancer (TNBC) highlighted a new systemic treatment option for brain metastases. Adebrelimab , a new immunotherapy agent combined with bevacizumab and platinum-based chemotherapy (cisplatin/carboplatin), provided impressive intracranial tumor control and a favorable safety profile in this challenging patient group.

Note: Adebrelimab (SHR-1316) is a next-generation anti-PD-L1 immunotherapy that is not currently approved by the US Food and Drug Administration (FDA). However, China's National Medical Products Administration (NMPA) approved it in 2023 for use with carboplatin and etoposide in extensive-stage small cell lung cancer (ES-SCLC).

Adebrelimab was developed by China-based Jiangsu Hengrui Pharmaceuticals. It is a PD-L1-targeted monoclonal antibody intended to help the immune system recognize and destroy tumor cells.

Adebrelimab is currently being evaluated in clinical trials across several cancers, including triple-negative breast, esophageal, and liver cancers.

🎯 Target Population: A Particularly Difficult-to-Treat Subgroup

When patients with TNBC develop brain metastases, median survival generally falls below 6 months, indicating a highly aggressive disease with limited responses to systemic treatment. Although local treatments such as radiotherapy take priority, the lack of effective systemic therapies creates a major unmet need.

The ABC study aims to address this gap.

Before the triple-drug combination tested in ABC, systemic treatments had limited effectiveness against brain metastases in TNBC. Conventional chemotherapy agents do not adequately cross the blood–brain barrier, so objective response rates in brain metastases were generally low. For example, studies of antibody–drug conjugates such as T-DM1 reported intracranial response rates of approximately 21% .

However, the new study combining adebrelimab, bevacizumab, and platinum-based chemotherapy reported 77.1%as the intracranial objective response rate against brain metastases in TNBC. This represents a substantial improvement over previous treatments.

🔬 ABC Study Design

• Phase: II
• Design: Single-arm, single-center
• Participants: 35 patients with TNBC and active brain metastases
• Treatment protocol:
  • Adebrelimab 20 mg/kg (day 1, Q3W)
  • Bevacizumab 7.5 mg/kg (day 1, Q3W)
  • Cisplatin 75 mg/m² or carboplatin AUC=5 (day 1, Q3W)
• Treatment duration: Until progression or intolerable adverse reactions

📊 Clinical Findings

Brain-Metastasis-Specific Efficacy

• 🧠 Intracranial objective response rate (CNS-ORR): 77.1% (5 complete responses and 22 partial responses)
• ✅ Intracranial clinical benefit rate (CNS-CBR): 80% (the proportion of patients who responded or remained progression-free for at least 24 weeks)
• ⏳ Median CNS-PFS (intracranial progression-free survival): 10 months (95% CI: 7.4–12.6)
• 🌡️ Median PFS (overall progression-free survival): 7.6 months (95% CI: 5.7–11.5)
• 🕊️ Median OS (overall survival): 16 months (95% CI: 11.7 – immature)

Safety Profile

• All patients (100%) experienced at least one treatment-related adverse reaction.
• Grade ≥3 adverse reactions: 48.6%
  • Neutropenia: 8.6%
  • Thrombocytopenia: 8.6%
• Serious adverse event: 1 patient (facial nerve disorder)
• No treatment-related deaths occurred.

🧠 Clinical Significance

This study suggests that the triple combination could offer a systemic solution for brain metastases in TNBC. Intracranial response and survival findings point to a level of success not previously achieved in this group.

Biomarkers such as PD-L1 positivity and the TNBC molecular subclassification developed by Fudan University were also shown to potentially predict response to this treatment.

🔍 Conclusion and Future Perspectives

The ABC study offers strong indications that brain metastases in TNBC can be controlled systemically. If validated in prospective randomized trials, adebrelimab + bevacizumab + platinum could become an effective systemic option in clinical practice.