ZURICH, May 31 (Reuters) - Roche's experimental drug that spurs the immune system to fight cancer shrank tumours in 43 percent of people with a specific type of metastatic bladder cancer, according to results of an early-stage trial published on Saturday.
The drug MPDL3280A is part of a closely-watched class of treatments known as anti-PDL1 therapies, which work by blocking a tumour's ability to evade the immune system's defences.
U.S. health regulators have granted the drug breakthrough therapy designation, which aims to fast-track the development and review times of drugs for serious or life-threatening conditions.
Data from the Phase I trial presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago found MPDL3280A shrank tumours in 13 out of 30 patients who had been previously treated for metastatic urothelial bladder cancer.
The patients were also identified as being PDL1 positive by a diagnostic test being developed by Roche.
"It's exciting to see a potential new treatment for bladder cancer patients who have been waiting a long time for new therapies," said Peter Johnson, chief clinician at Cancer Research UK whose experimental cancer medicine centre was used in the trial.
Bladder cancer is the ninth most common cancer worldwide resulting in around 145,000 deaths globally each year, Roche said.
The drug is an engineered antibody that targets a protein called PD-L1, for programmed death-ligand 1, and enables T cells of the immune system to more effectively attack cancer cells. PD-L1 is found on the surface of many cancer cells and impairs the immune system's ability to fight the disease. (Reporting by Caroline Copley, editing by Louise Heavens)