New Drug Can Put An End To Cancer’s Hide-And-Seek Game

A new drug in development has shown promising results in restricting cancer cells’ ability to hide from the immune system and reduced tumors in some patients by at least 30%. 

Immunotherapy treatments for cancer have improved survival rates, but due to cancer’s ability to play “hide-and-seek,” many drugs become ineffective. However, Greywolf Therapeutics, an Oxford-based biotech company that focuses on treatments for cancer and autoimmune diseases, developed a drug designed to “stop cancer cells concealing themselves from the immune system, allowing immunotherapy treatments to identify and destroy them.” 

A trial, led by the Christie NHS Foundation Trust in Manchester, England, tested 83 patients with cervical, bladder, liver, bowel, lung, or head and neck cancers. The patients were given the drug and immunotherapy treatment, cemiplimab. In the trial across the United Kingdom, France, Spain, and Australia, the research found tumors shrank in 26 patients, and 15 of those patients had tumor reductions by at least 30%. 

The drug, called GRWD5769, shrank tumors in all six cancer types and halted the progression of the disease for at least six months in 18% of the cervical cancer patients, 32% of liver cancer patients, 36% of bladder cancer patients, 38% of head and neck cancer patients, 51% of bowel cancer patients, and 55% of lung cancer patients. 

The results of the trial were presented at the 2026 American Society of Clinical Oncology’s annual meeting in Chicago by Professor Fiona Thistlethwaite, the medical director of the National Institute for Health and Care Research (NIHR) Manchester Clinical Research Facility at The Christie. She said that she is excited about the trial because it shows “strong signals of efficacy across six tumor types that have shown great resistance to immunotherapy, with very few side effects. That’s unusual at such an early stage.” 

Thistlethwaite told The Guardian, “For a drug that is given as a tablet, this is very impressive. It’s early days, and we need further studies, but this is a new drug with a new mechanism that clearly helps immunotherapy perform more effectively.”

The drug works by addressing an issue that has plagued scientists for decades: cancer’s ability to play hide-and-seek. The way the body fights foreign cells — bacteria and viruses — is by antigen-presenting cells (APCs) showing T-cells the external invaders, which then fight the disease. The problem with cancer cells is that they are not external invaders, but the body’s own cells, which become mutated. They coat themselves with PD-L1, a protein normal cells produce that works to hide their identity to T-cells, effectively playing hide-and-seek.

The new drug can “reveal hidden tumors through T-cell diversification and priming,” according to the Greywolf website, which means that through the drug inhibiting ERAP1, it removes cancer’s “invisibility cloak” and allows T-cells to detect tumor cells originally invisible.

Dr. Samuel Godfrey, Cancer Research UK’s research information lead, said that while immunotherapy has “transformed treatment for some cancers,” it doesn’t work for everyone. “This trial seems to show how this new drug could make immunotherapy more effective, including in some cases where immunotherapy had previously failed.”