Plitidepsin in adult patients with COVID-19 requiring hospital admission: A long-term follow-up analysis.

Introduction: The APLICOV-PC study assessed the safety and preliminary efficacy of plitidepsin in hospitalized adult patients with COVID-19. In this follow-up study (E-APLICOV), the incidence of post-COVID-19 morbidity was evaluated and any long-term complications were characterized. Methods: Between January 18 and March 16, 2022, 34 of the 45 adult patients who received therapy with plitidepsin in the APLICOV-PC study were enrolled in E-APLICOV (median time from plitidepsin first dose to E-APLICOV enrollment, 16.8 months [range, 15.2-19.5 months]). All patients were functionally autonomous with regard to daily living (Barthel index: 100) and had normal physical examinations. Results: From the APLICOV-PC date of discharge to the date of the extension visit, neither Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5) grade 3-4 complications nor QT prolongation or significant electrocardiogram (EKG) abnormalities were reported. Five (14.7%) patients had another COVID-19 episode after initial discharge from APLICOV-PC, and in 2 patients (5.9%), previously unreported chest X-ray findings were documented. Spirometry and lung-diffusion tests were normal in 29 (85.3%) and 27 (79.4%) patients, respectively, and 3 patients needed additional oxygen supplementation after initial hospital discharge. None of these patients required subsequent hospital readmission for disease-related complications. Discussion: In conclusion, plitidepsin has demonstrated a favorable long-term safety profile in adult patients hospitalized for COVID-19. With the constraints of a low sample size and a lack of control, the rate of post-COVID-19 complications after treatment with plitidepsin is in the low range of published reports. (ClinicalTrials.gov Identifier: NCT05121740; https://clinicaltrials.gov/ct2/show/NCT05121740).

Bioactive natural products in COVID-19 therapy.

The devastating COVID-19 pandemic has caused more than six million deaths worldwide during the last 2 years. Effective therapeutic agents are greatly needed, yet promising magic bullets still do not exist. Numerous natural products (cordycepin, gallinamide A, plitidepsin, telocinobufagin, and tylophorine) have been widely studied and play a potential function in treating COVID-19. In this paper, we reviewed published studies (from May 2021 to April 2022) relating closely to bioactive natural products (isolated from medicinal plants, animals products, and marine organisms) in COVID-19 therapy in vitro to provide some essential guidance for anti-SARS-CoV-2 drug research and development.

Unraveling the antiviral activity of plitidepsin against SARS-CoV-2 by subcellular and morphological analysis.

The pandemic caused by the new coronavirus SARS-CoV-2 has made evident the need for broad-spectrum, efficient antiviral treatments to combat emerging and re-emerging viruses. Plitidepsin is an antitumor agent of marine origin that has also shown a potent pre-clinical efficacy against SARS-CoV-2. Plitidepsin targets the host protein eEF1A (eukaryotic translation elongation factor 1 alpha) and affects viral infection at an early, post-entry step. Because electron microscopy is a valuable tool to study virus-cell interactions and the mechanism of action of antiviral drugs, in this work we have used transmission electron microscopy (TEM) to evaluate the effects of plitidepsin in SARS-CoV-2 infection in cultured Vero E6 cells 24 and 48h post-infection. In the absence of plitidepsin, TEM morphological analysis showed double-membrane vesicles (DMVs), organelles that support coronavirus genome replication, single-membrane vesicles with viral particles, large vacuoles with groups of viruses and numerous extracellular virions attached to the plasma membrane. When treated with plitidepsin, no viral structures were found in SARS-CoV-2-infected Vero E6 cells. Immunogold detection of SARS-CoV-2 nucleocapsid (N) protein and double-stranded RNA (dsRNA) provided clear signals in cells infected in the absence of plitidepsin, but complete absence in cells infected and treated with plitidepsin. The present study shows that plitidepsin blocks the biogenesis of viral replication organelles and the morphogenesis of virus progeny. Electron microscopy morphological analysis coupled to immunogold labeling of SARS-CoV-2 products offers a unique approach to understand how antivirals such as plitidepsin work.

Hunting the main protease of SARS-CoV-2 by plitidepsin: Molecular docking and temperature-dependent molecular dynamics simulations.

COVID-19 has shaken all the countries across the globe and researchers are trying to find promising antiviral to cure the patients suffering from infection and can decrease the death. Even, different nations are using repurposing drugs to cure the symptoms and these repurposing drugs are hydroxychloroquine, remdesivir, and lopinavir, and recently, India has recently given the approval for the 2-deoxy-D-glucose for emergency purpose to cure the patients suffering from the COVID-19. Plitidepsin is a popular molecule and can be used in treatment of myeloma. Plitidepsin was explored by scientists experimentally against the COVID-19 and was given to the patient. It is found to be more a promising repurposing drug against the COVID-19 than the remdesivir. Therefore, there is a need to understand the interaction of plitidepsin with the main protease of SARS-CoV-2. Molecular docking of the plitidepsin against Mpro of SARS-CoV-2 was performed and the binding energy was found to be - 137.992 kcal/mol. Furthermore, authors have performed the molecular dynamics simulations of the main protease of SARS-CoV-2 in presence of plitidepsin at 300 and 325 K. It was found that the plitidepsin binds effectively with the main protease of SARS-CoV-2 at 300 K.

Computational Prediction of the Potential Target of SARS-CoV-2 Inhibitor Plitidepsin via Molecular Docking, Dynamic Simulations and MM-PBSA Calculations.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication depends on the interaction between the viral proteins and the human translation machinery. The cytotoxic peptide plitidepsin was found to inhibit CoV-2 up to 90 % at a concentration of 0.88 nM. In vitro studies suggest that this activity may be attributed to the inhibition of the eukaryotic translation elongation factor 1A (eEF1A). However, recent reports raised the potential for other cellular targets which plitidepsin may use to exert its potent antiviral activity. The lack of data about these potential targets represents a major limitation for its structural optimization. This work describes the use of a molecular modeling approach to rationalize the in vitro antiviral activity of plitidepsin and to identify potential cellular targets. The developed protocol involves an initial molecular docking step followed by molecular dynamics and binding free energy calculations. The results reveal the potential for plitidepsin to bind to the active site of the key enzyme SARS-CoV-2 RdRp. The results also highlight the importance of van der Waals interactions for proper binding with the enzyme. We believe that the results presented in this study could provide the grounds for the optimization of plitidepsin analogs as SARS-CoV-2 inhibitors.

Potential role of marine species-derived bioactive agents in the management of SARS-CoV-2 infection.

COVID-19, caused by the SARS-CoV-2 outbreak, has resulted in a massive global health crisis. Bioactive molecules extracted or synthesized using starting material obtained from marine species, including griffithsin, plitidepsin and fingolimod are in clinical trials to evaluate their anti-SARS-CoV-2 and anti-HIV efficacies. The current review highlights the anti-SARS-CoV-2 potential of marine-derived phytochemicals explored using in silico, in vitro and in vivo models. The current literature suggests that these molecules have the potential to bind with various key drug targets of SARS-CoV-2. In addition, many of these agents have anti-inflammatory and immunomodulatory potentials and thus could play a role in the attenuation of COVID-19 complications. Overall, these agents may play a role in the management of COVID-19, but further preclinical and clinical studies are still required to establish their role in the mitigation of the current viral pandemic.

Plitidepsin: Mechanisms and Clinical Profile of a Promising Antiviral Agent against COVID-19.

Current standard treatment of COVID-19 lacks in effective antiviral options. Plitidepsin, a cyclic depsipeptide authorized in Australia for patients with refractory multiple myeloma, has recently emerged as a candidate anti-SARS-CoV-2 agent. The aim of this review was to summarize current knowledge on plitidepsin's clinical profile, anti-tumour and anti-SARS-CoV-2 mechanisms and correlate this with available or anticipated, preclinical or clinical evidence on the drug's potential for COVID-19 treatment.PubMed, Scopus, CENTRAL, clinicaltrials.gov, medRxiv and bioRxiv databases were searched.Plitidepsinexerts its anti-tumour and antiviral properties primarily through acting on isoforms of the host cell's eukaryotic-translation-elongation-factor-1-alpha (eEF1A). Through inhibiting eEF1A and therefore translation of necessary viral proteins, it behaves as a "host-directed" anti-SARS-CoV-2 agent. In respect to its potent anti-SARS-CoV-2 properties, the drug has demonstrated superior ex vivo efficacy compared to other host-directed agents and remdesivir, and it might retain its antiviral effect against the more transmittable B.1.1.7 variant. Its well-studied safety profile, also in combination with dexamethasone, may accelerate its repurposing chances for COVID-19 treatment. Preliminary findings in hospitalized COVID-19 patients, have suggested potential safety and efficacy of plitidepsin, in terms of viral load reduction and clinical resolution. However, the still incomplete understanding of its exact integration into host cell-SARS-CoV-2 interactions, its intravenous administration exclusively purposing it for hospital settings the and precocity of clinical data are currently considered its chief deficits. A phase III trial is being planned to compare the plitidepsin-dexamethasone regimen to the current standard of care only in moderately affected hospitalized patients. Despite plitidepsin's preclinical efficacy, current clinical evidence is inadequate for its registration in COVID-19 patients.Therefore, multicentre trials on the drug's efficacy, potentially also studying populations of emerging SARS-CoV-2 lineages, are warranted.

Anti-viral treatment for SARS-CoV-2 infection: A race against time amidst the ongoing pandemic.

Remdesivir (GS-5734), a drug initially developed to treat hepatitis C and Ebola virus disease, was the first approved treatment for severe coronavirus disease 2019 (COVID-19). However, apart from remdesivir, there is a paucity of other specific anti-viral agents against SARS-CoV-2 infection. In 2017, researchers had documented the anti-coronavirus potential of remdesivir in animal models. At the same time, trials performed during two Ebola outbreaks in Africa showed that the drug was safe. Although vaccines against SARS-CoV-2 infection have emerged at an enormously high speed, equivalent results from efforts towards the development of anti-viral drugs, which could have played a truly life-saving role in the current stage of the pandemic, have been stagnating. In this review, we will focus on the current treatment options for COVID-19 which mainly consist of repurposed agents or treatments conferring passive immunity (convalescent plasma or monoclonal antibodies). Additionally, potential specific anti-viral therapies under development will be reviewed, such as the decoy miniprotein CTC-445.2d, protease inhibitors, mainly against the Main protein Mpro, nucleoside analogs, such as molnupiravir and compounds blocking the replication transcription complex proteins, such as zotatifin and plitidepsin. These anti-viral agents seem to be very promising but still require meticulous clinical trial testing in order to establish their efficacy and safety. The continuous emergence of viral variants may pose a real challenge to the scientific community towards that end. In this context, the advent of nanobodies together with the potential administration of a combination of anti-viral drugs could serve as useful tools in the armamentarium against COVID-19.

[Plitidepsin, an inhibitor of the cell elongation factor eEF1a, and molnupiravir an analogue of the ribonucleoside cytidine, two new chemical compounds with intense activity against SARS-CoV-2]. / Plitidepsina, un inhibidor del factor de elongación celular eEF1a y molnupiravir un análogo del ribonucleósido citidina, dos nuevos compuestos químicos con intensa actividad frente al SARS-CoV-2.

The knowledge of the replicative cycle of SARS-CoV-2 and its interactions with cellular proteins has opened a new therapeutic possibility based on blocking those essential for the virus. The cellular protein elongation factor eEF1A could be a good target. Among its natural inhibitors are didemnins and their related chemical compounds such as plitidepsin. In human cell culture, this compound is capable of inhibiting the virus with a potency 27,5 times that of remdesivir. It must be administered intravenously. Of the ribonucleoside analogues, molnupiravir (MK-4483/EIDD-2801) (hydroxy-cytidine) determines a lethal mutagenesis on SARS-CoV-2. In animals, after oral administration, the pulmonary viral load decreases 25,000 times and when administered as prophylaxis, approximately 100,000 times. It prevents the transmission of the virus and eliminates its presence in the oropharynx. Both chemicals have started Phase I / II human clinical trials.

Identification of Plitidepsin as Potent Inhibitor of SARS-CoV-2-Induced Cytopathic Effect After a Drug Repurposing Screen.

There is an urgent need to identify therapeutics for the treatment of Coronavirus disease 2019 (COVID-19). Although different antivirals are given for the clinical management of SARS-CoV-2 infection, their efficacy is still under evaluation. Here, we have screened existing drugs approved for human use in a variety of diseases, to compare how they counteract SARS-CoV-2-induced cytopathic effect and viral replication in vitro. Among the potential 72 antivirals tested herein that were previously proposed to inhibit SARS-CoV-2 infection, only 18 % had an IC50 below 25 µM or 102 IU/ml. These included plitidepsin, novel cathepsin inhibitors, nelfinavir mesylate hydrate, interferon 2-alpha, interferon-gamma, fenofibrate, camostat along the well-known remdesivir and chloroquine derivatives. Plitidepsin was the only clinically approved drug displaying nanomolar efficacy. Four of these families, including novel cathepsin inhibitors, blocked viral entry in a cell-type specific manner. Since the most effective antivirals usually combine therapies that tackle the virus at different steps of infection, we also assessed several drug combinations. Although no particular synergy was found, inhibitory combinations did not reduce their antiviral activity. Thus, these combinations could decrease the potential emergence of resistant viruses. Antivirals prioritized herein identify novel compounds and their mode of action, while independently replicating the activity of a reduced proportion of drugs which are mostly approved for clinical use. Combinations of these drugs should be tested in animal models to inform the design of fast track clinical trials.

Plitidepsin: a Repurposed Drug for the Treatment of COVID-19.

Finding antivirals to reduce coronavirus disease 2019 (COVID-19) morbidity and mortality has been challenging. Large randomized clinical trials that aimed to test four repurposed drugs, hydroxychloroquine, lopinavir-ritonavir, interferon beta 1a, and remdesivir, have shown that these compounds lack an impact on the COVID-19 course. Although the phase III COVID-19 vaccine trial results are encouraging, the search for effective COVID-19 therapeutics should not stop. Recently, plitidepsin (aplidin) demonstrated highly effective preclinical activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Its antiviral activity was 27.5-fold more potent than that of remdesivir (K. M. White, R. Rosales, S. Yildiz, T. Kehrer, et al., Science, 2021, https://science.sciencemag.org/content/early/2021/01/22/science.abf4058). Plitidepsin, a repurposed drug developed for the treatment of multiple myeloma, targets the host translation cofactor eEF1A. Plitidepsin has shown efficacy in animal models and phase I/II human trials. Although plitidepsin is administered intravenously and its toxicity profile remains to be fully characterized, this compound may be a promising alternative COVID-19 therapeutic.