New antiretroviral agents in the existing classes are being developed with the aim of producing drugs with more favourable toxicity profiles and activity against drug-resistant HIV. These include a new CCR5 inhibitor cenicriviroc (Phase III) that also has activity blocking CCR2, thereby dampening inflammation. There is also a monoclonal antibody directed against CCR5 (PRO 140) currently under development in Phase II trials that is administered subcutaneously. New classes of antiretroviral agents currently in phase II stage of development are the attachment inhibitor fostemsavir that binds to the gp120 protein on HIV-1, interfering with its ability to bind to the CD4 cell receptor, and the maturation inhibitor BMS-9551. Maturation inhibitors block a step in the processing of the group-specific antigen (Gag) polyprotein, necessary for virion maturation, leading to the release of immature non-infectious virions. In addition to new antiretroviral agents in current classes, or in new classes, there are multiple compounds based on currently available antiretroviral drugs. These include long acting injectable versions of rilpivirine (Phase I) and a dolutegravir analogue (cabotegravir) that is being developed in long-acting injectable and oral forms (Phase II).