The present invention relates to derivatives of borrelidin that are useful in medicine, e.g. in the treatment of cancer or B-cell malignancies, or other diseases in which angiogenesis contributes to the pathology including ophthalmic disorders such as diabetic retinopathy as well as age related macular degeneration (AMD), corneal neovascularisation and retinopathy or prematurity. The present invention also provides methods for the production of these compounds and their use in medicine, in particular in the treatment and/or prophylaxis of cancer or B-cell malignancies and other diseases in which angiogenesis is implicated in the pathogenic process.