UK drug colossus Astrazeneca and US peer Eli Lilly have agreed to collaborate on the hot area of immuno-oncology, where drugs encourage the body's immune system to help battle cancer.The FTSE 100 group, which last month agreed a major collaboration with Celgene, will combine one of its experimental immuno-oncology drugs with an existing treatment of Lilly's in new clinical trials focused on advanced solid tumours.The two companies said on Friday that AstraZeneca's anti-PD-L1 immunotherapy drug MEDI4736 will be tested alongside Lilly's already approved antiangiogenic drug Cyramza, also known as ramucirumab, which starves tumours of blood supply.MEDI4736 is a monoclonal antibody that helps the body identify the location of tumour cells that might normally avoid detection.The early-stage Phase I trial will be run by Lilly, though additional details of the collaboration, including tumours to be studied and financial terms, were not disclosed.Astrazeneca's strategy for its immuno-oncology drugs has been to work external partners to create combinations, or cocktails, of drugs.Robert Iannone, Astrazeneca's head of immuno-oncology development, said: "We believe that combination therapy in immuno-oncology has the potential to transform the way cancer is treated."He said MEDI4736 in particular has emerged as a cornerstone of the group's immuno-oncology pipeline targeting multiple tumour types."Our collaboration with Lilly is a great addition to our program and provides the opportunity to explore another exciting, novel combination that could deliver important clinical benefit to cancer patients."