Baylor Researchers Unveil CS18, a Compound That Reverses Tumor Resistance to Standard Therapies

Key points

• Researchers at Baylor College of Medicine identified CS18 as a promising inhibitor of TopBP1, a protein described as a 'biological switchboard' that regulates multiple cancer-promoting pathways.
• The drug was developed by screening thousands of compounds, with CS18 emerging as the most effective candidate after modifying an initial lead compound known as 3B6.
• CS18 reduces the activity of cancer drivers such as MYC and mutant p53 while increasing the activity of genes that suppress uncontrolled growth.
• In laboratory tests, CS18 demonstrated efficacy against triple-negative breast cancer, ovarian cancer, lung adenocarcinoma, lung squamous cell carcinoma, and acute myeloid leukemia.
• When combined with existing drugs like osimertinib, CS18 restored sensitivity in resistant lung cancer cells and increased cell death more effectively than the standard drugs alone.
• Animal model studies showed significant tumor growth reduction without major weight loss or other signs of toxicity, indicating a favorable safety profile in early testing.

Background

This development follows a trend in 2026 of novel approaches to combat cancer resistance and improve treatment efficacy. Earlier this year, UT Austin researchers reported a two-part drug that forces cancer cells to burn more sugar while blocking fatty-acid metabolism, killing cells in mice and human cell lines. Additionally, advancements in AI-driven personalized cancer care and reengineered HPV vaccines have highlighted the shift toward targeted and adaptive therapies. While these previous innovations focused on metabolic disruption or immune system activation, the CS18 approach targets a central regulatory hub to disable multiple defense mechanisms simultaneously.

Why it matters

Therapeutic resistance remains a primary obstacle in cancer treatment, often leading to patient relapse after initial success. By targeting TopBP1, a node that influences several survival pathways at once, CS18 offers a strategy to prevent or reverse resistance. This could extend the effectiveness of current standard-of-care drugs, potentially improving outcomes for patients with aggressive cancers like triple-negative breast cancer and lung adenocarcinoma. If successful in further development, CS18 could serve as a component in combination therapies that maintain drug sensitivity over longer periods.

What to watch

The researchers suggest that CS18 warrants further development as a potential component of combination cancer therapies. Future studies will likely focus on clinical trials to validate the efficacy and safety observed in animal models. The goal is to determine if CS18 can consistently prevent resistance from emerging or make resistant cancers responsive to existing treatments in human patients.