A Phase 2 Study of Pimodivir (JNJ-63623872) in Combination With Oseltamivir in Elderly and Nonelderly Adults Hospitalized With Influenza A Infection: OPAL Study

Retracted and republished from: "The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs"

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the Food and Drug Administration are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. These recommended antivirals are currently effective for major subtypes of IVs as the compounds target conserved domains in neuraminidase or polymerase acidic (PA) protein. However, this trend may gradually change due to the selection of antiviral drugs and the natural evolution of IVs. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Tackling Influenza A virus by M2 ion channel blockers: Latest progress and limitations

Influenza outbreaks cause pandemics in millions of people. The treatment of influenza remains a challenge due to significant genetic polymorphism in the influenza virus. Also, developing vaccines to protect against seasonal and pandemic influenza infections is constantly impeded. Thus, antibiotics are the only first line of defense against antigenically distinct strains or new subtypes of influenza viruses. Among several anti-influenza targets, the M2 protein of the influenza virus performs several activities. M2 protein is an ion channel that permits proton conductance through the virion envelope and the deacidification of the Golgi apparatus. Both these functions are critical for viral replication. Thus, targeting the M2 protein of the influenza virus is an essential target. Rimantadine and amantadine are two well-known drugs that act on the M2 protein. However, these drugs acquired resistance to influenza and thus are not recommended to treat influenza infections. This review discusses an overview of anti-influenza therapy, M2 ion channel functions, and its working principle. It also discusses the M2 structure and its role, and the change in the structure leads to mutant variants of influenza A virus. We also shed light on the recently identified compounds acting against wild-type and mutated M2 proteins of influenza virus A. These scaffolds could be an alternative to M2 inhibitors and be developed as antibiotics for treating influenza infections.

The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the FDA are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Notably, owing to the high variability of IVs, no drug exists that can effectively treat all types and subtypes of IVs. Moreover, the current trend of drug resistance is likely to continue as the viral genome is constantly mutating. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Discovery of a potent inhibitor targeting the cap-binding domain of the PB2 subunit of influenza RNA-dependent RNA polymerase

Influenza pandemics have emerged as a significant global public health and security concern. PB2, a crucial subunit of the influenza RNA-dependent RNA polymerase (RdRP), has been identified as a promising target for influenza treatment. We herein report the discovery of a potent novel PB2 inhibitor, 7-51A, with a KD value of 1.64 nM as determined by ITC. The high activity of 7-51A was elucidated by the co-crystal structure of the PB2-7-51A complex, and comparative analysis revealed unique interactions that had never been observed before. The preliminary pharmacological evaluation indicated that 7-51A exhibited commendable cellular safety, hepatic microsomal metabolic safety and stability. Collectively, 7-51A was found to be an effective PB2 inhibitor and could be used as a lead compound for further studies.

Antiviral Approaches against Influenza Virus

Preventing and controlling influenza virus infection remains a global public health challenge, as it causes seasonal epidemics to unexpected pandemics. These infections are responsible for high morbidity, mortality, and substantial economic impact. Vaccines are the prophylaxis mainstay in the fight against influenza. However, vaccination fails to confer complete protection due to inadequate vaccination coverages, vaccine shortages, and mismatches with circulating strains. Antivirals represent an important prophylactic and therapeutic measure to reduce influenza-associated morbidity and mortality, particularly in high-risk populations. Here, we review current FDA-approved influenza antivirals with their mechanisms of action, and different viral- and host-directed influenza antiviral approaches, including immunomodulatory interventions in clinical development. Furthermore, we also illustrate the potential utility of machine learning in developing next-generation antivirals against influenza.

Synthesis and structure-activity optimization of 7-azaindoles containing aza-β-amino acids targeting the influenza PB2 subunit

The PB2 subunit of influenza virus polymerase has been demonstrated as a promising drug target for anti-influenza therapy. In this work, 7-azaindoles containing aza-β³- or β^2,3 -amino acids were synthesized possessing a good binding affinity of PB2. The aza-β-amino acid moieties with diverse size, shape, steric hindrance and configuration were investigated. Then a lead HAA-09 was validated, and the attached aza-β³-amino acid moiety with acyclic tertiary carbon side chain well occupied in the key hydrophobic cavity of PB2_cap binding domain. Importantly, HAA-09 displays potent polymerase inhibition capacity, low cytotoxicity (selectivity index up to 2915) as well as robust anti-viral activity against A/WSN/33 (H1N1) virus and oseltamivir-resistant H275Y variant. Moreover, HAA-09 exhibited druggability with high plasma stability (t_1/2 ≥ 12 h) and no obvious hERG inhibition (IC₅₀ > 10 μM). Also, HAA-09 demonstrated a favorable safety profile when orally administrated in healthy mice at a high dose of 40 mg/kg QD for consecutive 3 days. Besides, in vivo therapeutic efficacy (85.7% survival observed at the day 15 post infection) was demonstrated when HAA-09 was administrated orally at 12.5 mg/kg BID starting 48 h post infection for 9 days. These data support that exploring the interactions between side chains on aza-β³- or β^2,3 -amino acid moieties and hydrophobic pocket of PB2_cap binding domain is a potential medicinal chemistry strategy for developing potent PB2 inhibitors.

Drug Cocktail Formulation via Circuit Design

Electronic circuits intuitively visualize and quantitatively simulate biological systems with nonlinear differential equations that exhibit complicated dynamics. Drug cocktail therapies are a powerful tool against diseases that exhibit such dynamics. We show that just six key states, which are represented in a feedback circuit, enable drug-cocktail formulation: 1) healthy cell number; 2) infected cell number; 3) extracellular pathogen number; 4) intracellular pathogenic molecule number; 5) innate immune system strength; and 6) adaptive immune system strength. To enable drug cocktail formulation, the model represents the effects of the drugs in the circuit. For example, a nonlinear feedback circuit model fits measured clinical data, represents cytokine storm and adaptive autoimmune behavior, and accounts for age, sex, and variant effects for SARS-CoV-2 with few free parameters. The latter circuit model provided three quantitative insights on the optimal timing and dosage of drug components in a cocktail: 1) antipathogenic drugs should be given early in the infection, but immunosuppressant timing involves a tradeoff between controlling pathogen load and mitigating inflammation; 2) both within and across-class combinations of drugs have synergistic effects; 3) if they are administered sufficiently early in the infection, anti-pathogenic drugs are more effective at mitigating autoimmune behavior than immunosuppressant drugs.

Design, Synthesis, Biological Evaluation, and Molecular Dynamics Simulation of Influenza Polymerase PB2 Inhibitors

The PB2 subunit of the influenza RNA-dependent RNA polymerase (RdRp) has been identified as a promising target for the treatment of influenza. To expand the chemical space of the known influenza polymerase PB2 inhibitor-pimodivir (formerly VX-787) and improve its pharmacokinetic profile, two pimodivir analogs containing 2,3-dihydro-imidazopyridine fragment (comp. I and comp. II) were designed, synthesized, and evaluated for anti-influenza virus activity. In the cytopathic effect (CPE) inhibition assay, comp. I and comp. II showed IC₅₀ values of 0.07 and 0.09 μM for A/Puerto Rico/8/34 (H1N1) and 0.04 and 0.07 μM for A/Hong Kong/8/68 (H3N2), respectively. Protein-binding affinity assay results showed a concentration-dependent association and dissociation pattern, with K_D values of 1.398 and 1.670 μM, respectively. In vitro metabolic stability assays showed that comp. I and comp. II exhibited good stability to liver microsomes and considerably less sensitivity to aldehyde oxidase compared to pimodivir. The binding modes of comp. I and comp. II were similar to those of VX-787; however, comp. I and comp. II had lower structural adaptability to PB2 than VX-787. Our results provide helpful information regarding the structure-activity relationship for the design of novel PB2 inhibitors and a reference for the development of drugs containing 2,3-dihydro-imidazopyridine fragments.

Pregnancy Outcomes in Women With SARS-CoV-2 Infection During the First and Second Waves of the COVID-19 Pandemic in a Tertiary Care Hospital in Ayodhya, Uttar Pradesh, India: A Comparative Study

Introduction Pregnancy is an altered immunological state and not necessarily an immune-compromised state. These immune changes subject pregnant women to increased susceptibility to infection. During the coronavirus disease 2019 (COVID-19) pandemic, pregnant women were more susceptible to serious illness for reasons other than their immune response. The purpose of this study was to compare the feto-maternal outcome (morbidity and mortality) in relation to pre-existing maternal co-morbidities, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-related disease severity, and its impact on the mode of delivery and long-term sequelae in pregnant women in the first and second waves of the COVID-19 pandemic. Materials and methods This was a hospital-based comparative study carried out on 101 pregnant patients during the first wave (April 2020 to December 2020) and 22 patients in the second wave (March 2021 to July 2021) of the COVID-19 pandemic, in Rajashri Dashrath Autonomous State Medical College, Ayodhya, India. All pregnant women with COVID-19 in the first and second waves were included. Non-pregnant patients with COVID-19 infection, pregnant patients lost to follow-up, pregnant patients without COVID-19 infection, and patients in the puerperal period were excluded. Results Seventy-three (72.27%) patients in the first wave and 12 (54.54%) in the second wave were asymptomatic. Those with mild disease numbered 20 (25.74%) in the first wave and six (27.27%) in the second wave. Disease severity was more in the second wave, that is four (18.18%) as compared to one (0.99%) in the first wave. Severe anemia was the most common co-morbidity associated with both first (n=4, 3.96%) and second (n=5, 22.72%) waves. Four (6.45%) spontaneous abortions occurred in the first wave as compared to three (20%) in the second wave. Intensive care unit (ICU) admission was more in the second wave (n=4, 26.66%) as compared to the first wave (n=1, 1.61%). Two (13.33%) maternal deaths occurred in the second wave and none in the first wave. Cesarean sections in both the first and second waves were performed for obstetric indications only. No newborns tested positive in the COVID-19 reverse transcription-polymerase chain reaction (RT-PCR) in the first and second waves at the time of birth; however, three (4.83%) tested positive on day five of birth in the first wave. Fever was the most common presentation in newborns; seven (11.26%) in the first wave and three (20%) in the second wave. No neonatal death occurred in the first or second waves. No congenital anomalies were noted in the first or second waves of COVID-19. Conclusion In this study, we found that the maximum number of COVID-19-positive pregnant patients in both the first and second waves of COVID-19 were either asymptomatic or had mild infections. Second-wave infection was more lethal as compared to the first wave in terms of adverse maternal as well as fetal outcomes. No gestational age was an exception to the severity of disease and its adverse feto-maternal outcome. In our study, maternal co-morbidities did not impact the overall outcome. All cesarean sections were performed for indications other than COVID-19 infection. Long-term sequelae associated with COVID-19 were seen in both groups but more so in the second wave. No long-term sequelae like congenital anomalies in the babies were associated with COVID-19 either in the first or second wave.

Preclinical and clinical developments for combination treatment of influenza

Antiviral drugs are an important measure of control for influenza in the population, particularly for those that are severely ill or hospitalised. The neuraminidase inhibitor (NAI) class of drugs, including oseltamivir, have been the standard of care (SOC) for severe influenza illness for many years. The approval of drugs with novel mechanisms of action, such as baloxavir marboxil, is important and broadens potential treatment options for combination therapy. The use of antiviral treatments in combination for influenza is of interest; one potential benefit of this treatment strategy is that the combination of drugs with different mechanisms of action may lower the selection of resistance due to treatment. In addition, combination therapy may become an important treatment option to improve patient outcomes in those with severe illness due to influenza or those that are immunocompromised. Clinical trials increasingly evaluate drug combinations in a range of patient cohorts. Here, we summarise preclinical and clinical advances in combination therapy for the treatment of influenza with reference to immunocompromised animal models and clinical data in hospitalised patient cohorts where available. There is a wide array of drug categories in development that have also been tested in combination. Therefore, in this review, we have included polymerase inhibitors, monoclonal antibodies (mAbs), host-targeted therapies, and adjunctive therapies. Combination treatment regimens should be carefully evaluated to determine whether they provide an added benefit relative to effectiveness of monotherapy and in a variety of patient cohorts, particularly, if there is a greater chance of an adverse outcome. Safe and effective treatment of influenza is important not only for seasonal influenza infection, but also if a pandemic strain was to emerge.

Strategies for fighting pandemic virus infections: Integration of virology and drug delivery

Respiratory viruses have sometimes resulted in worldwide pandemics, with the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) being major participants. Long-term efforts have made it possible to control the influenza virus, but seasonal influenza continues to take many lives each year, and a pandemic influenza virus sometimes emerges. Although vaccines for coronavirus disease 2019 (COVID-19) have been developed, we are not yet able to coexist with the SARS-CoV-2. To overcome such viruses, it is necessary to obtain knowledge about international surveillance systems, virology, ecology and to determine that immune responses are effective. The information must then be transferred to drugs. Delivery systems would be expected to contribute to the rational development of drugs. In this review, virologist and drug delivery system (DDS) researchers discuss drug delivery strategies, especially the use of lipid-based nanocarriers, for fighting to respiratory virus infections.

Susceptibility of widely diverse influenza a viruses to PB2 polymerase inhibitor pimodivir

Pimodivir exerts an antiviral effect on the early stages of influenza A virus replication by inhibiting the cap-binding function of polymerase basic protein 2 (PB2). In this study, we used a combination of sequence analysis and phenotypic methods to evaluate pimodivir susceptibility of influenza A viruses collected from humans and other hosts. Screening PB2 sequences for substitutions previously associated with reduced pimodivir susceptibility revealed a very low frequency among seasonal viruses circulating in the U.S. during 2015–2020 (<0.03%; 3/11,934) and among non-seasonal viruses collected in various countries during the same period (0.2%; 18/8971). Pimodivir potently inhibited virus replication in two assays, a single-cycle HINT and a multi-cycle FRA, with IC₅₀ values in a nanomolar range. Median IC₅₀ values determined by HINT were similar for both subtypes of seasonal viruses, A(H1N1)pdm09 and A(H3N2), across three seasons. Human seasonal viruses with PB2 substitutions S324C, S324R, or N510K displayed a 27–317-fold reduced pimodivir susceptibility by HINT. In addition, pimodivir was effective at inhibiting replication of a diverse group of animal-origin viruses that have pandemic potential, including avian viruses of A(H5N6) and A(H7N9) subtypes. A rare PB2 substitution H357N was identified in an A(H4N2) subtype poultry virus that displayed >100-fold reduced pimodivir susceptibility. Our findings demonstrate a broad inhibitory activity of pimodivir and expand the existing knowledge of amino acid substitutions that can reduce susceptibility to this investigational antiviral.