Targeting CXCR4 in HIV cell-entry inhibition.

CXCR4 and CCR5 constitute the two major coreceptors for HIV-1 entry into host cells. In the course of an HIV-infection, a coreceptor switch takes place in approximately half of the patients - from R5 HIV-1 (CCR5 utilizing) strains to X4 HIV-1 (CXCR4 utilizing) strains. Treatment of HIV-infected individuals with CXCR4 antagonists delays the onset of AIDS by preventing the CCR5 to CXCR4 coreceptor switch. In addition to the endogenous CXCR4 and CCR5 ligands, other chemokines, for example the human herpesvirus 8 encoded CC-chemokine, vCCL2, and modifications hereof, have proven efficient HIV-1 cell-entry inhibition through chemokine receptor interaction. However, pharmacokinetic and immunogenic drawbacks of chemokines and peptidic/peptoid compounds have brought the attention towards small-molecule antagonists, such as AMD3100, that displays high specificity and affinity towards CXCR4, but unfortunately no oral bioavailability. The hunt for orally active small-molecule CXCR4 antagonists led to the development of monocyclam-based compounds, and recently to the non-cyclam antagonist AMD070, which is orally active and currently in Phase II clinical trial as anti-HIV treatment. Current review provides an overview of the drug discovery within the field of anti-HIV treatment targeting CXCR4 spanning from natural occurring and modified chemokines, to HIV-mimicking peptides and peptoids ending at the non-peptide antagonists.