Drug interactions between antineoplastic and antiretroviral therapies: Implications and management for clinical practice

Despite the impact of combined antiretroviral therapy (cART) on human immunodeficiency virus (HIV)-related mortality, malignancies remain the second most common cause of death in HIV infection in developed countries. In addition to the AIDS-defining malignancies, other cancers such as Hodgkin's lymphoma and anal cancer, are more frequent in HIV-infected patients who survive longer even though they do not have complete immune restoration The use of concomitant antineoplastic chemotherapy and cART have been demonstrated to be feasible and effective in patients with HIV-related malignancies; however, many drugs used in cART regimens have the potential for causing drug interactions as a result of their ability to either inhibit or induce the cytochrome P450 (CYP) enzyme system. Since many antineoplastic drugs are also metabolised by the CYP system, co-administration with cART could result in either drug accumulation and possible toxicity, or rapid drug metabolism and decreased efficacy. Unfortunately, very limited prospective interaction data are available to safely guide the combined use of cART and chemotherapy. This paper reviews the potential drug interactions and therapeutic considerations of the antiretroviral agents used to treat HIV and the most common anticancer agents used in the treatment of malignancies found in patients with HIV infection.