An experimental tablet that strips cancer cells of their 'invisibility cloak' has been shown to shrink tumours by at least 30% in six common cancer types, according to early trial results. The drug, GRWD5769, was tested in 83 patients across the UK, France, Spain and Australia, all of whom had previously failed to respond to treatment.
The study, led by the Christie NHS Foundation Trust in Manchester, found that tumours shrank in 26 patients, with 15 experiencing reductions of 30% or more. The drug works by inhibiting an enzyme called ERAP1, which cancer cells use to hide from the immune system. This allows immunotherapy treatments, such as cemiplimab, to identify and destroy the tumour cells.
Results presented at the American Society of Clinical Oncology meeting in Chicago showed that the drug halted disease progression for at least six months in a significant proportion of patients: 18% for cervical cancer, 32% for liver cancer, 36% for bladder cancer, 38% for head and neck cancer, 51% for bowel cancer, and 55% for lung cancer.
Prof Fiona Thistlethwaite, principal investigator from the Christie, said: 'For a drug that is given as a tablet, this is very impressive. It's early days, but this is a new drug with a new mechanism that clearly helps immunotherapy perform more effectively.' The tablets, developed by Oxford-based Greywolf Therapeutics, were well tolerated and can be taken at home.
Immunotherapy, which enlists T-cells to attack cancer, fails in about two-thirds of patients because tumours can hide. GRWD5769 removes this cloak, making cancer cells visible. 'What excites me is the strong signals of efficacy across six tumour types with very few side-effects,' Thistlethwaite added. 'That's unusual at such an early stage.'
The trial remains ongoing, with a larger study planned. Prof Stefan Symeonides, UK principal investigator from the Edinburgh Cancer Centre, described the results as 'exciting' and said it was 'fantastic to see our patients benefiting'.
