Results from recently completed studies suggested that the NH<sub>2</sub>-naphthyl-diarylpyrimidine <b>JX-7</b> displayed remarkable inhibitory activity against wild-type HIV-1 (EC<sub>50</sub> = 5 nM) and numerous clinically observed variants in MT-4 cells; however, its high cytotoxicity (CC<sub>50</sub> = 19 μM) precluded its further development as a clinical candidate. One approach we took to improve the safety involved replacing the naphthyl of <b>JX-7</b> with biphenyl to provide a series of novel NH<sub>2</sub>-biphenyl-DAPYs. Investigation of the structure-activity relationships (SARs) led to the identification of <b>4ab</b>, a potent NNRTI with significantly reduced cytotoxicity (CC<sub>50</sub> = 120 μM), approximately 6-fold lower than <b>JX-7</b>, which maintained remarkable anti-HIV-1 activity against wild-type HIV-1 (EC<sub>50</sub> = 1.9 nM) and multiple mutant strains simultaneously. Also, <b>4ab</b> displayed weak CYP sensitivity, little inhibition of hERG, and no apparent <i>in vivo</i> acute toxicity. These promising results demonstrate that <b>4ab</b> can be used as a drug candidate for HIV-1 therapy.