Targeting the HIV-1 NNRTI Entrance Channel: Structure-Guided Optimization for Enhanced Safety and Selectivity

Previous studies showed JK-4b potently inhibited wild-type and clinical HIV-1 variants, but its high cytotoxicity halted clinical development. In this work, with JK-4b as the lead, a series of non-nucleoside reverse transcriptase inhibitors (NNRTIs) with lower cytotoxicity and high selectivity were designed through targeting the HIV-1 NNRTI entrance channel. Investigation of the structure-activity relationships identified 9n, a potent NNRTI with significantly reduced cytotoxicity and high selectivity, which was better than JK-4b and etravirine. Simultaneously, this compound displayed single-digit nanomolar potency against five viral strains (HIV-1 IIIB, L100I, K103N, Y181C, and E138K). Importantly, it maintained potent activity against F227L/V106A and K103N/Y181C (EC50 = 0.030 μM and 0.035 μM, respectively), which was comparable to etravirine. Furthermore, 9n exhibited minimal cytochrome P450 inhibition and good metabolic stability in human liver microsomes. Collectively, these findings support 9n as a promising NNRTI candidate for further development.