[A long-awaited - but prohibitively expensive - therapy].

After many years of development, a gene therapy for haemophilia B has demonstrated effectiveness and durability, at least over a time span of three years. It has just been approved (as Hemgenix®) by the FDA in the USA and by the EMA in the EU. However, the multimillion price tag of this treatment is a serious problem for healthcare systems and for patients, and raises a number of thorny issues about marketing practices of the pharmaceutical industry.