Discovery and Synthesis of First-Generation Single-Drug “Cocktails” to Combat HIV

Saturday, 14 February 2015
Exhibit Hall (San Jose Convention Center)
Anthony R. Prosser, Emory University, Atlanta, GA
Current HIV regimens require at least three mechanistically distinct antiviral drugs to arrest ongoing viral replication and restore immune function. Unfortunately, these so-called “drug cocktails” come with significant financial burden, a continually emerging set of long term side effects, and the potential for resistance if not taken as prescribed. Resistance develops due to the plasticity of the viral genome which is able to produce several isoforms of the proteins that are targeted by antiretroviral therapy. Thus, it would be advantageous to target specific host proteins which exist as a single isoform and are not significantly responsive to selective pressures. Of particular interest are the chemokines CCR5 and CXCR4, which are required for HIV cellular entry. Unfortunately, inhibition of CCR5 facilitates viral evolution toward CXCR4 entry and vice versa. Therefore, it is necessary to inhibit both chemokines simultaneously to completely blockade HIV. In pursuit of such a class of compounds we designed a virtual screen of the Sigma-Aldrich marketplace using Bayesian statistical methods and the current database of CCR5 and CXCR4 antagonists. Our computational filters utilized 2d-fingerprints and HIV activities to select a small subset of less than twenty compounds from the over five million screened in silico. This subset of compounds was tested in an anti-viral screening assay (CCR5/CXCR4- expressing MAGI cells), and yielded a synthetically tractable scaffold, allowing us to elucidate structure activity relationships (SARs). The synthesized series demonstrated good potency against HIV utilizing both the CCR5 and CXCR4 receptor. This entry inhibition mechanism was validated by a thorough mechanistic study. Additionally, the molecules were also serendipitously active against HIV reverse transcription, yielding three mechanisms of anti-HIV activity. In summary, we have discovered and synthesized a novel series of small molecules that demonstrate a unique cornucopia of host/viral mechanisms of HIV inhibition. These compounds are lead structures for the development of a novel class of multi-target HIV agents, and may yield an effective single-drug “cocktail”.