A literature review of the patent application publications on cabotegravir - an HIV integrase strand transfer inhibitor

Current status of the small molecule anti-HIV drugs in the pipeline or recently approved

Human Immunodeficiency Virus (HIV) is the causative agent of Acquired Immunodeficiency Syndrome (AIDS) with high morbidity and mortality rates. Treatment of AIDS/HIV is being complicated by increasing resistance to currently used antiretroviral (ARV) drugs, mainly in low- and middle-income countries (LMICs) due to drug misuse, poor drug supply and poor treatment monitoring. However, progress has been made in the development of new ARV drugs, targeting different HIV components (Fig. 1). This review aims at presenting and discussing the progress made towards the discovery of new ARVs that are at different stages of clinical trials as of July 2024. For each compound, the mechanism of action, target biomolecule, genes associated with resistance, efficacy and safety, class, and phase of clinical trial are discussed. These compounds include analogues of nucleoside reverse transcriptase inhibitors (NRTIs) - islatravir and censavudine; non-nucleoside reverse transcriptase inhibitors (NNRTIs) - Rilpivirine, elsulfavirine and doravirine; integrase inhibitors namely cabotegravir and dolutegravir and chemokine coreceptors 5 and 2 (CC5/CCR2) antagonists for example cenicriviroc. Also, fostemsavir is being developed as an attachment inhibitor while lenacapavir, VH4004280 and VH4011499 are capsid inhibitors. Others are maturation inhibitors such as GSK-254, GSK3532795, GSK3739937, GSK2838232, and other compounds labelled as miscellaneous (do not belong to the classical groups of anti-HIV drugs or to the newer classes) such as obefazimod and BIT225. There is a considerable progress in the development of new anti-HIV drugs and the effort will continue since HIV infections has no cure or vaccine till now. Efforts are needed to reduce the toxicity of available drugs or discover new drugs with new classes which can delay the development of resistance.

Fluorine in anti-HIV drugs approved by FDA from 1981 to 2023

Human immunodeficiency virus (HIV) is the etiological agent of acquired immunodeficiency syndrome (AIDS). Nowadays, FDA has approved over thirty antiretroviral drugs grouped in six categories. Interestingly, one-third of these drugs contain different number of fluorine atoms. The introduction of fluorine to obtain drug-like compounds is a well-accepted strategy in medicinal chemistry. In this review, we summarized 11 fluorine-containing anti-HIV drugs, focusing on their efficacy, resistance, safety, and specific roles of fluorine in the development of each drug. These examples may be of help for the discovery of new drug candidates bearing fluorine in their structures.

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.

Synthesis, Biological Evaluation, and Molecular Modeling Studies of New 8-methyl-4-oxo-1,4-dihydroquinoline-3-carbohydrazides as Potential Anti-HIV Agents

Background

The development of a highly safe and potent scaffold is a significant challenge in anti-HIV drug discovery.

Objectives

This study aimed at developing a novel series of anti-HIV agents based on HIV integrase inhibitor pharmacophores.

Methods

A novel series of 8-methyl-4-oxo-1,4-dihydroquinoline-3-carbohydrazide derivatives featuring various substituted benzoyl and N-phenyl carboxamide and carbothioamide moieties were designed and synthesized.

Results

According to the biological evaluation, all the developed compounds were effective against HIV at concentrations lower than 150 µM, associated with no significant cytotoxicity (CC50 > 500 µM).

Conclusions

Compound 8b, possessing a 4-fluorobenzoyl group, was the most potent compound, with an EC50 of 75 µM. Docking studies revealed that the binding modes of designed compounds are similar to the known HIV integrase inhibitors.

Cabenuva: the last FDA-approved drug to treat HIV

INTRODUCTION

The conventional combination antiretroviral therapy (cART) besides all its benefits, exhibited poor adherence to daily pill administration, life-long treatment period and emergence of viral resistance. The development of long-acting (LA) drugs have changed the management of common medical conditions for human immunodeficiency virus (HIV). Cabenuva is the first LA antiretroviral injectable drug composed of nano-formulation of cabotegravir (CAB) and rilpivirine (RPV).

AREAS COVERED

In this review article, we aim to have a brief overview of results of major clinical trials which administrated cabenuva for patients considering the efficacy and safety profiles. Moreover, we discuss about CAB and RPV chemical structure, mechanism of action, ‎activity against drug-sensitive and resistant HIV and pharmacodynamics/ pharmacokinetics properties.

EXPERT OPINION

Based on the results of the ATLAS and FLAIR trials, cabenuva regimen once-monthly has shown equal effectivity to oral cART in maintaining HIV-1 suppression in patients. Furthermore, ATLAS-2M study revealed the non-inferiority of cabenuva regimen every 8 weeks compared to every 4 weeks. The injectable LA ART, reduces the number of treatment intake as well as increases adherence especially in patients with HIV-related stigma. Administration of extended-release agents probably minimize the risk of treatment-related toxicity and resistance related to sub-optimal adherence to oral ART, so cabenuva can be suggested as a suitable alternative for HIV infection control in current era.

Development of an Analytical Method for Determination of Related Substances and Degradation Products of Cabotegravir Using Analytical Quality by Design Principles

Cabotegravir is one of the newly approved human immunodeficiency virus (HIV) integrase enzyme inhibitors used for the prevention and treatment of HIV infection. It is the first approved long-acting injectable antiretroviral therapy for HIV and is also very effective in combination with rilpivirine, a non-nucleoside reverse transcriptase inhibitor. Therefore, future drug development involving cabotegravir can be expected. We developed an ultrahigh performance liquid chromatography (UHPLC) method compatible with mass spectrometry for the determination of eight cabotegravir impurities. The described method is able to differentiate cabotegravir and its related substances as well as its degradation products. Analytical quality by design principles were used for method development. The method is robust within the defined method operable design region: flow rate = 0.32-0.40 mL/min; column temperature = 30-40 °C; pH of mobile phase A = 3.25-3.75, and the final percent of acetonitrile in gradient = 50.0-60.0%. Inside the method operable design region, a working optimal point was selected: pump flow rate = 0.36 mL/min; column temperature = 35 °C; pH of mobile phase A = 3.5, and final percent of acetonitrile in gradient = 55%. Method validation was performed, and the following parameters were verified: accuracy, repeatability, linearity, response factors, detection limit, and quantification limit. All method validation results were within selected criteria. The presented method could be used for the development of new pharmaceutical products based on cabotegravir.

Integrase Strand Transfer Inhibitor (INSTI) Genotypic Resistance Analysis in Treatment-nNaive, INSTI Free Antiretroviral-Experienced and INSTI-Experienced Turkish Patients Infected with HIV-1

BACKGROUND AND OBJECTIVE

Integrase strand transfer inhibitors (INSTIs) are currently the standard of practice for first-line HIV therapy for most patients. We evaluated the mutations associated with INSTI resistance in naive HIV-1 infected patients and treated them with antiretrovirals (ART).

METHODS

The study, conducted in the 2018 - 2020 period, included 50 ART-naïve patients, 69 INSTI free ART-experienced patients, and 82 INSTI-experienced patients. INSTI resistance mutations were interpreted using the Stanford University HIVdb Program algorithm.

RESULTS

INSTI resistance was not detected in ART naïve patients. At least one INSTI resistance mutation was detected in 10% of the INSTI-free patients and 29% of the INSTI-treated patients. Major INSTI-mutations E138K, Y143R, S147G, Q148R, N155H, and E157Q were found in raltegravir. Additional mutations, E92Q, E138K, G140A, S147G, and Q148R were found in elvitegravir; E192Q, E138K/T, G140A/S, S147G, Q148H/R, N155H, E157Q were found in dolutegravir (DTG) experienced patients. According to all drug classes, drug resistance mutation prevalences were determined at the rate of 60%, 46%, and 46% in the RAL, EVG, and DTG groups, respectively.

CONCLUSION

Our findings provide data for treatment and resistance management of INSTIs and may provide feedback for INSTIs resistance surveillance consensus-building efforts. In viral rebound under INSTI treatment, INSTI-resistant mutations follow typical INSTI resistance pathways and high resistance rates. INSTI resistance genotypic analysis should be considered before any DTG-based regimes can be initiated in the future, and reduced DTG susceptibility should be carefully monitored and investigated.

Development of thermosensitive and mucoadhesive gels of cabotegravir for enhanced permeation and retention profiles in vaginal tissue: A proof of concept study

As an effective anti-HIV drug, cabotegravir (CAB) is currently administered via oral and injection routes, leading to several drawbacks, such as poor oral bioavailability and problems in the injection application process, as well as low drug concentration in vaginal tissue of woman patients. To overcome these issues, for the first time, we formulated CAB into three types of vaginal gels, considering the benefits of vaginal tissue as a delivery route. Thermosensitive gel, mucoadhesive gel, and the combination of these gels were developed as suitable carriers for CAB. Pluronics®, hydroxy propyl methyl cellulose (HPMC), Carbomer and poly(ethylene glycol) (PEG) 400 were used as thermosensitive, mucoadhesive and permeation enhancer agents, respectively. The gels were evaluated for their thermosensitive and mucoadhesive properties, as well as their pH values, viscosities, gel erosions, drug content recovery, in vitro drug release, ex vivo permeation, ex vivo retention, hemolytic activities, Lactobacillus inhibition activities and in vivo irritation properties. The results showed that all formulations showed desired characteristics for vaginal administration. Importantly, all formulations did not show hemolytic activities and inhibitions to Lactobacillus as normal bacteria in the vagina. Furthermore, no irritation in the vaginal tissues of the rats was observed by histopathological studies. Considering the thermosensitive and mucoadhesive properties, the combination of Pluronic® F127, Pluronic F68, and HPMC in thermosensitive-mucoadhesive vaginal gels was selected as the optimum dosage form for CAB as this formulation was able to provide ease administration due to its liquid form at room temperature. The use of PEG in this formulation was able to increase the penetrability of CAB through vaginal tissue with 0.61 ± 0.05 mg and 17.28 ± 0.95 mg of CAB being able to penetrate and localize in the vagina, respectively. Essentially, the optimum formulation was retained in the vaginal mucosa for>8 h. To conclude, further extensive in vivo studies should now be conducted to evaluate the efficacy of this approach.

Understanding of cabotegravir degradation through isolation and characterization of key degradation products and kinetic studies

Cabotegravir is a novel human immunodeficiency virus integrase enzyme inhibitor used for prevention and treatment of HIV infection. The combinational final dosage form, as extended release injection suspension in combination with rilpivirine and as cabotegravir tablets (for lead-in therapy), was recently approved in Canada, EU and in USA and is currently seeking approval also in other countries. The subject of this investigation was to study the degradation of cabotegravir under different stress conditions as per the International Council for Harmonization (ICH) guidelines. The drug substance was found to be stable in thermal, photolytic and basic stress conditions, but degraded under acidic and oxidative stress conditions. It was determined that four main degradation products of cabotegravir are formed in forced degradation studies. All four main degradation products were isolated using preparative chromatography and subjected to NMR and HRMS analysis in order to determine their structure. We proposed degradation pathways of cabotegravir under acidic stress conditions in solution based on the structure of isolated degradation products, cabotegravir degradation kinetic studies and degradation studies on two isolated key degradation products. Moreover, degradation pathway to predominant oxidation degradation product is proposed based on the adduct of cabotegravir and peroxide species, which was identified by LC-HRMS analysis. This is the first report to the best of our knowledge that describes characterized cabotegravir forced degradation impurities and provides insights into its degradation pathways.