Dose proportional inhibition of HIV-1 replication by mycophenolic acid and synergistic inhibition in combination with abacavir, didanosine, and tenofovir.

Mycophenolate mofetil (MMF), a therapeutically used inhibitor of inosine monophosphate dehydrogenase is hydrolyzed to its active metabolite mycophenolic acid (MPA) in vivo. MPA exhibits anti-HIV activity in vitro. We tested MPA alone and in combination with abacavir (ABC), didanosine (DDI), lamivudine (3TC) and tenofovir (TFV) against wild-type human immunodeficiency virus type-1 (HIV-1) and nucleoside reverse transcriptase inhibitor (NRTI)-resistant HIV-1. MPA (62.5-500 nM), when combined with ABC or DDI, synergistically enhanced activity against wild-type HIV and the NRTI-resistant HIV clone DRSM34. MPA also enhanced the activity of TFV against both wild-type HXB2 and TFV-resistant strain HIV(K65R), in a more than additive manner. No significant antiproliferative effect of MPA (< or =0.25 microM) alone or in the presence of ABC, DDI and TFV was observed. This indicates that the antiviral effects of MMF may be clinically achievable without fully blocking T-cell proliferation or inducing immunosuppression. These findings provide further rationale for the clinical testing of MMF in combination with ABC, DDI, and TFV.