A new cancer treatment can stop the disease advancing in patients who are resistant to immunotherapy, doctors have discovered.

Immunotherapy uses the immune system to target and kill cancer cells, and can save lives when other treatment options, such as surgery, radiotherapy or chemotherapy, have failed. However, it cannot help all patients, and some tumours can evolve to resist it.

Now oncologists in the UK have found a two-pronged treatment – immunotherapy combined with guadecitabine, a novel experimental drug – can reverse a cancer’s resistance to immunotherapy. Patients expected to die after exhausting all treatment options survived much longer, they found.

The combination of pembrolizumab, an immunotherapy drug, and guadecitabine, a next-generation DNA hypomethylating agent, halted the advance of cancer in more than a third of patients enrolled in the early phase 1 trial. The results are published in the Journal for ImmunoTherapy of Cancer.

The dual combination could become an effective new weapon against several forms of cancer, experts at the Institute of Cancer Research and Royal Marsden NHS foundation trust said.