BA1106 Antibody Shows Promise in Early Trials In Solid Tumors

BA1106 is China’s first innovative anti-CD25 monoclonal antibody to enter clinical trials for advanced solid tumors.

Targeting CD25 (interleukin-2 receptor alpha), a protein highly expressed on regulatory T cells (Tregs) that suppress immune responses, BA1106 is designed to enhance the body’s ability to fight cancer. Research confirms CD25’s presence in prostate cancer, linked to poor prognosis, making this therapy highly relevant.

The biological role of CD25 in prostate cancer involves mediating IL-2 signaling, which can have dual effects. While IL-2 can activate effector T cells and natural killer cells, it can also promote Treg expansion, complicating its therapeutic use. Targeting CD25 aims to deplete Tregs, thereby shifting the balance toward anti-tumor immunity.

Unlike other anti-CD25 antibodies like daclizumab, BA1106 does not block IL-2 signaling, preserving the activation of CD8+ and CD4+ T cells and natural killer cells while depleting Tregs through antibody-dependent cellular cytotoxicity (ADCC).

The Phase I trial tested it in 31 patients with refractory, advanced, or metastatic solid tumors, showed BA1106 was well-tolerated, with one dose-limiting toxicity (grade 3 hyponatremia) at 432 μg/kg and no maximum tolerated dose reached.
Treatment-related adverse events (TRAEs) occurred in 67.7% of patients, mostly mild.
Among 26 patients assessed for efficacy, nine achieved stable disease, yielding a 34.6% disease control rate. Tumor shrinkage and durable control were observed in four patients with other cancers, including a small-cell neuroendocrine carcinoma (76 weeks, ongoing) and a pleural mesothelioma (33.9 weeks), suggesting potential for prostate cancer, though specific outcomes for this cancer type were not detailed.

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