Scientists Find Why Chemo Fails, Opening New Hope

Scientists at Oregon Health & Science University just figured out why some of the deadliest cancers shrug off chemotherapy like water off a duck's back. The answer could unlock new treatments for patients who've run out of options.

The culprit is a protein called MYC, already notorious for turbocharging tumor growth in most human cancers. Researchers discovered it has a secret second job: rushing to damaged DNA like a repair crew and fixing the very destruction that chemotherapy causes.

"Our work shows that MYC isn't just helping cancer cells grow. It's also helping them survive some of the very treatments designed to kill them," said senior author Dr. Rosalie Sears, who leads cancer research at OHSU.

The discovery explains a frustrating mystery in cancer treatment. Chemotherapy and radiation work by overwhelming tumor cells with DNA damage. But if cancer cells can quickly patch up that damage, they survive and keep growing.

Graduate researcher Gabriel Cohn found that when DNA breaks, a modified version of MYC travels directly to the damaged spots. Instead of its usual job switching genes on and off, it recruits repair proteins to fix the breaks.

Cancer cells with active MYC repaired damage faster and survived conditions that should have killed them. The effect showed up strongest in pancreatic cancer, one of the hardest cancers to treat.

The team tested their findings using tumor samples and pancreatic cancer cells from real patients. Cancers with high MYC activity showed more DNA repair happening and worse outcomes for patients.

The Bright Side

For decades, scientists considered MYC "undruggable" because its structure makes it nearly impossible for medications to target safely. But this new understanding of how MYC works during DNA repair offers a fresh angle of attack.

Researchers don't need to shut down everything MYC does in healthy cells. They just need to block its repair function in tumors. That precision could make cancer cells vulnerable to treatment again without harming normal tissue.

OHSU is already testing the approach in human patients. A clinical trial is giving people with advanced pancreatic cancer a first-in-class MYC blocker called OMO-103. Doctors take biopsies before and after treatment to see exactly how blocking MYC changes the tumors.

The trial represents hope for a cancer that desperately needs better options. Pancreatic cancer kills quickly, often because tumors resist standard chemotherapy.

"In pancreatic cancer, MYC appears to help tumors tolerate extreme stress from rapid growth, poor blood supply, and chemotherapy," Sears explained. Interfering with that survival mechanism could tip the scales back toward treatments working.

The research appears in the journal Genes & Development and marks a significant step toward making one of cancer's most important proteins finally druggable.