Scientists at Baylor College of Medicine made a new experimental medicine called CS18. Early tests suggest it could help regular cancer drugs work better against tumors that have become hard to treat.
Blocking a Key Cancer Switch
Instead of aiming at just one cancer pathway, the team looked for a way to hit a bigger control hub in the cell. That hub is a protein called TopBP1, which acts like a switchboard for many signals that help cancer grow and survive.
One part of TopBP1, called BRCT7/8, talks to several important proteins: MIZ1 (which slows down the cancer driver MYC), mutant p53 (which can turn into a bad protein), and PLK1 and CIP2A (which help cancer cells divide). Because it connects to many helpers, BRCT7/8 is a promising target.
How CS18 Was Created
The researchers screened thousands of chemicals on computers and in the lab. One of them, named 3B6, showed some ability to block BRCT7/8. After many tweaks, they ended up with CS18, the most powerful version.
When CS18 attaches to BRCT7/8, it weakens the actions of MYC and mutant p53, slows down DNA‑repair proteins, and makes cancer cells more likely to die. It also turns on genes that stop cells from growing out of control.
Testing Across Many Cancer Types
CS18 worked in lab cells from several cancers, including triple‑negative breast cancer, ovarian cancer, two kinds of lung cancer, and acute myeloid leukemia. It was gentler on normal, healthy cells.
The drug was even stronger when mixed with existing medicines such as PARP inhibitors or the lung‑cancer drug osimertinib. In resistant lung‑cancer cells, adding CS18 made the cells sensitive to osimertinib again, leading to more cell death.
Animal studies showed that tumors grew much slower when CS18 was combined with other drugs, and the animals stayed healthy with no major weight loss.
What This Could Mean for Patients
These early results suggest CS18 could become part of future combination therapies. By attacking the cancer’s central switch, it might keep tumors from becoming resistant or help bring resistant tumors back under control.