Human cytomegalovirus and transplantation: drug development and regulatory issues

Cytomegalovirus (CMV) infection is highly prevalent worldwide and can cause serious disease among immunocompromised individuals, including persons with HIV and transplant recipients on immunosuppressive therapies. It can also result in congenital cytomegalovirus when women are infected during pregnancy. Treatment and prevention of CMV in solid organ and haematopoietic stem cell transplant recipients is accomplished in one of three ways: (1) prophylactic therapy to prevent CMV viraemia; (2) pre-emptive therapy for those with low levels of replicating virus; and (3) treatment for established disease. Despite the high prevalence of CMV, there are few available approved drug therapies, and those that are available are hampered by toxicity and less-than-optimal efficacy. New therapies are being developed and tested; however, inconsistency in standardisation of virus levels and questions about potential endpoints in clinical trials present regulatory hurdles that must be addressed. This review covers the current state of CMV therapy, drugs currently under investigation, and clinical trial issues and questions that are in need of resolution.