Drug-drug interactions in HIV positive cancer patients.

Clinically relevant drug-drug interactions (DDIs) refer to the pharmacological or clinical response to the administration or co-exposure of a drug with another drug that modifies the patient's response. Treatment regimens, which include agents that are involved in the cytochrome P450 (CYP450) enzyme system and transporter systems, such as P-glycoprotein may be associated with higher risk of clinically significant drug interactions. In addition, potential DDIs increase with the increasing number of concomitant drugs. HIV positive cancer patients who receive concomitant chemotherapy and combination antiretroviral therapy (cART) may achieve better response rates and higher rates of survival than those who receive chemotherapy alone, but they may be at increased risk of drug interactions. DDIs in HIV positive cancer patients receiving concomitant chemotherapy and cART may increase or decrease antineoplastic drug concentrations, potentially resulting in life threatening interactions, increased toxicity or loss of efficacy. Avoiding and managing potential interactions between cART and antineoplastic agents is an increasingly important challenge. Based on the current literature, more safety and pharmacokinetic studies are needed with the aim to document a clear survival benefit for patients undergoing chemotherapy and concomitant or sequential administration of cART.