Identification of spirocyclic or phosphate substituted quinolizine derivatives as novel HIV-1 integrase inhibitors: a patent evaluation of WO2016094197A1, WO2016094198A1 and WO2016154527A1

New designs for HIV-1 integrase inhibitors: a patent review (2018-present)

INTRODUCTION

Combination antiretroviral therapy (cART) has dramatically reduced morbidity and mortality of HIV-1-infected patients. Integrase strand transfer inhibitors (INSTIs) play an important role as a key drug in cART. The second-generation INSTIs are very potent, but due to the emergence of highly resistant viruses and the demand for more conveniently usable drugs, the development of 'third-generation' INSTIs and mechanistically different inhibitors is actively being pursued.

AREAS COVERED

This article reviews the patents (from 2018 to the present) for two classes of HIV-1 integrase inhibitors of INSTIs and integrase-LEDGF/p75 allosteric inhibitors (INLAIs).

EXPERT OPINION

Since the approval of the second-generation INSTI dolutegravir, the design of new INSTIs has been mostly focused on its scaffold, carbamoylpyridone (CAP). This CAP scaffold is used not only for HIV-1 INSTIs but also for drug discoveries targeting other viral enzymes. With the approval of cabotegravir as a regimen of long-acting injection in combination with rilpivirine, there is a growing need for longer-acting agents. INLAIs have been intensely studied by many groups but have yet to reach the market. However, INLAIs have recently been reported to also function as a latency promoting agent (LPA), indicating further development possibilities.

Structural Biology of HIV Integrase Strand Transfer Inhibitors

Integrase (IN) strand transfer inhibitors (INSTIs) are recent compounds in the antiretroviral arsenal used against HIV. INSTIs work by blocking retroviral integration; an essential step in the viral lifecycle that is catalyzed by the virally encoded IN protein within a nucleoprotein assembly called an intasome. Recent structures of lentiviral intasomes from simian immunodeficiency virus (SIV) and HIV have clarified the INSTI binding modes within the intasome active sites and helped elucidate an important mechanism of viral resistance. The structures provide an accurate depiction of interactions of intasomes and INSTIs to be leveraged for structure-based drug design. Here, we review these recent structural findings and contrast with earlier studies on prototype foamy virus intasomes. We also present and discuss examples of the latest chemical compounds that show promising inhibitory potential as INSTI candidates.

A novel substrate directed multicomponent reaction for the syntheses of tetrahydro-spiro[pyrazolo[4,3-f]quinoline]-8,5'-pyrimidines and tetrahydro-pyrazolo[4,3-f]pyrimido[4,5-b]quinolines via selective multiple C-C bond formation under metal-free conditions

A versatile and substrate oriented multicomponent reaction for the syntheses of novel highly diastereoselective tetrahydro-1'H-spiro[pyrazolo[4,3-f]quinoline-8,5'-pyrimidine]-2',4',6'(3'H)-triones (d.r. up to 20 : 1 (syn : anti)) and tetrahydro-8H-pyrazolo[4,3-f]pyrimido[4,5-b]quinoline-8,10(9H)-diones via formation of selective multiple C-C bonds under identical reaction conditions (viz. ethanol as a reaction medium and deep eutectic mixture as a catalyst) is demonstrated. Both approaches involve mild reaction conditions, use of non-hazardous solvents, and facilitate good to excellent reaction yields of the target compounds.

Current insights into anti-HIV drug discovery and development: a review of recent patent literature (2014-2017)

INTRODUCTION

To deal with the rapid emergence of drug resistance challenges, together with the difficulty to eradicate the virus, off-target effects and significant cumulative drug toxicities, it is still imperative to develop next-generation anti-HIV agents with novel chemical classes or new mechanisms of action.

AREAS COVERED

We primarily focused on current strategies to discover novel anti-HIV agents. Moreover, examples of anti-HIV lead compounds were mainly selected from recently patented publications (reported between 2014 and 2017). In particular, 'privileged structure'-focused substituents decorating approach, scaffold hopping, natural-product diversification and prodrug are focused on. Furthermore, exploitation of new compounds with unexplored mechanisms of action and medicinal chemistry strategies to deplete the HIV reservoir were also described. Perspectives that could inspire future anti-HIV drug discovery are delineated.

EXPERT OPINION

Even if a large number of patents have been disclosed recently, additional HIV inhibitors are still required, especially novel chemical skeletons displaying a unexploited mechanism of action. Current medicinal chemistry strategies are inadequate, and appropriate and new methodologies and technologies should be exploited to identify novel anti-HIV drug candidates in a time- and cost- effective manner.