British-Swedish pharma giant AstraZeneca has expanded one of its biggest cancer drug trials investigating a new therapy in several types of cancer.

The MYSTIC trial is testing the company’s durvalumab in gastric, pancreatic and a number of blood cancers.

Unlike traditional chemotherapies, durvalumab belongs to a new wave of therapies that boost a patient’s own immune system in order to destroy cancer.

The specific molecule the drug targets is called PD-L1 – a protein that suppresses immune cell activity. It has been shown to be over-expressed in many types of cancer.

The aim of the MYSTIC trial is to analyse durvalumab’s effectiveness both on its own as a monotherapy and in combination with other drugs. Although the trial’s main purpose will still be investigating the drug’s use as a combination therapy, AstraZeneca has now made the drug’s use as a monotherapy a primary objective.

Two other trials looking at the drug as a monotherapy and as a combination therapy will be expanded also.

The drug is currently being tested in more than 30 clinical trials in combination with other targeted therapies.

If shown to be successful in trials, the drug could deliver sales in the multibillions for AstraZeneca. It will be up against some big players in the market though, namely Bristol-Myers Squibb’s lung cancer treatment Opdivo – which recorded third quarter sales of $920 million – and Merck’s Keytruda, which has just been approved for first-line treatment in a specific type of lung cancer.