AstraZeneca's MedImmune unit has signed an agreement with Pfizer for the latter's tremelimumab, a CTLA-4 monoclonal antibody which is a potential cancer treatment.

Under the terms of the deal, MedImmune will assume global development rights to tremelimumab, while Pfizer will retain the rights to use drug with specified types of combination therapies. Terms of the agreement were not disclosed.

MedImmune plans to explore tremelimumab in a number of potential cancer indications and its head of R&D, Bahija Jallal, said that "adding another immunotherapeutic approach to our oncology pipeline, one which may employ the immune system itself to fight cancer, exemplifies our continued commitment to embracing this new era of cancer care". Anders Ekblom, AstraZeneca's chief of global medicines development, added that this project "to further explore and advance tremelimumab showcases our synergies in marrying world-class biologics expertise with global development and commercialisation capabilities in oncology".

Development of tremelimumab has been a tricky business for the past few years. In April 2008, Pfizer discontinued a late-stage trial of the drug as a treatment for melanoma after a review of interim data showed that the drug would not demonstrate superiority to standard chemotherapy.

However, in January 2010 the company signed a deal with Debiopharm which involves the Switzerland-headquartered firm conducting a Phase III trial of tremelimumab for the treatment of patients with unresectable, Stage IV melanoma. An analysis from the terminated study threw up a biomarker which will be used in patient selection for the trial.