CCR5 and HIV infectious disease: AMD3100 was not further developed for the treatment of HIV infections essentially because of two reasons: (i) AMD3100 was not effective against the M-tropic CCR5 HIV strains, a problem that could be circumvented by the concomitant (oral) use of a CCR5 antagonist, maraviroc (Selzentry®), and (ii) it had to be injected subcutaneously, as it was not orally bioavailable.