Fosbretabulin (also known as combretastatin A-4 phosphate or CA4P) is a microtubule destabilizing experimental drug, a type of vascular-targeting agent, a drug designed to damage the vasculature (blood vessels) of cancer tumours causing central necrosis.

[2] In July 2007, the pharmaceutical company OXiGENE initiated a 180-patient phase III clinical trial of fosbretabulin in combination with carboplatin for the treatment of anaplastic thyroid cancer.

[3] There is currently no fully FDA approved treatment for this form of cancer.

By 2017, it had completed multiple clinical trials (e.g. for solid tumours,[4] non-small cell lung cancer[5]) with more in progress.

This antineoplastic or immunomodulatory drug article is a stub.