Baylor researchers develop CS18 drug to counter cancer therapy resistance

September 22, 2026 at 05:00 AM2 min

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Researchers at Baylor College of Medicine have developed an experimental drug, CS18, that may help cancer treatments work against resistant tumors. The study, published in Science Advances, provides early evidence supporting further investigation of CS18 as a possible future cancer treatment.

Key Facts

The experimental drug CS18 was developed by researchers at Baylor College of Medicine.
CS18 targets the TopBP1-BRCT7/8 interaction, a biological switchboard regulating multiple cancer pathways.
In laboratory tests, CS18 reduced cancer-promoting activities of MYC and mutant p53 and increased cancer cell death.
CS18 showed effects across triple-negative breast cancer, ovarian cancer, lung adenocarcinoma, lung squamous cell carcinoma, and acute myeloid leukemia cells.
CS18 was less toxic to non-cancerous cells compared to cancer cells.

Targeting Cancer's Survival Network

The researchers aimed to develop a drug that interferes with a broader control center involved in several cancer-promoting processes at once. Their target was topoisomerase IIß-binding protein 1 (TopBP1), described as a 'biological switchboard' regulating multiple pathways associated with cancer growth and survival. The BRCT7/8 switch on TopBP1 interacts with key regulators of cancer growth, including MIZ1, mutant p53, PLK1, and CIP2A. Disrupting this central control point could produce longer-lasting treatment responses and help overcome resistance.

Developing CS18

Researchers screened thousands of chemicals using computer modeling and laboratory experiments to find a compound capable of blocking BRCT7/8. The screening identified a compound known as 3B6, which was then modified and tested in numerous versions. CS18 emerged as the most effective candidate among the modified molecules. When CS18 binds to BRCT7/8, cancer-promoting activities of MYC and mutant p53 decreased, DNA repair proteins became less active, and cancer cells were more likely to die. CS18 also increased the activity of genes that stop uncontrolled cancer growth, reducing several defenses that help cancer cells survive therapy.

Testing Across Multiple Cancers

The effects of CS18 were observed in several types of cancer cells, including triple-negative breast cancer, ovarian cancer, lung adenocarcinoma, lung squamous cell carcinoma, and acute myeloid leukemia. CS18 was less toxic to non-cancerous cells, indicating a potential therapeutic window. The study, published in Science Advances, provides early evidence supporting further investigation of CS18 as a possible future cancer treatment.