Plitidepsin as an Immunomodulator against Respiratory Viral Infections.

Plitidepsin is a host-targeted compound known for inducing a strong anti-SARS-CoV-2 activity, as well as for having the capacity of reducing lung inflammation. Because IL-6 is one of the main cytokines involved in acute respiratory distress syndrome, the effect of plitidepsin in IL-6 secretion in different in vitro and in vivo experimental models was studied. A strong plitidepsin-mediated reduction of IL-6 was found in human monocyte-derived macrophages exposed to nonproductive SARS-CoV-2. In resiquimod (a ligand of TLR7/8)-stimulated THP1 human monocytes, plitidepsin-mediated reductions of IL-6 mRNA and IL-6 levels were also noticed. Additionally, although resiquimod-induced binding to DNA of NF-κB family members was unaffected by plitidepsin, a decrease in the regulated transcription by NF-κB (a key transcription factor involved in the inflammatory cascade) was observed. Furthermore, the phosphorylation of p65 that is required for full transcriptional NF-κB activity was significantly reduced by plitidepsin. Moreover, decreases of IL-6 levels and other proinflammatory cytokines were also seen in either SARS-CoV-2 or H1N1 influenza virus-infected mice, which were treated at low enough plitidepsin doses to not induce antiviral effects. In summary, plitidepsin is a promising therapeutic agent for the treatment of viral infections, not only because of its host-targeted antiviral effect, but also for its immunomodulatory effect, both of which were evidenced in vitro and in vivo by the decrease of proinflammatory cytokines.

PM534, an Optimized Target-Protein Interaction Strategy through the Colchicine Site of Tubulin.

Targeting microtubules is the most effective wide-spectrum pharmacological strategy in antitumoral chemotherapy, and current research focuses on reducing main drawbacks: neurotoxicity and resistance. PM534 is a novel synthetic compound derived from the Structure-Activity-Relationship study on the natural molecule PM742, isolated from the sponge of the order Lithistida, family Theonellidae, genus Discodermia (du Bocage 1869). PM534 targets the entire colchicine binding domain of tubulin, covering four of the five centers of the pharmacophore model. Its nanomolar affinity and high retention time modulate a strikingly high antitumor activity that efficiently overrides two resistance mechanisms in cells (detoxification pumps and tubulin ßIII isotype overexpression). Furthermore, PM534 induces significant inhibition of tumor growth in mouse xenograft models of human non-small cell lung cancer. Our results present PM534, a highly effective new compound in the preclinical evaluation that is currently in its first human Phase I clinical trial.

Quantitative determination of lurbinectedin, its unbound fraction and its metabolites in human plasma utilizing ultra-performance LC-MS/MS.

AIMS: Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) methods to quantify total lurbinectedin, its plasma protein binding to derive the unbound fraction and its main metabolites 1',3'-dihydroxy-lurbinectedin (M4) and N-desmethyl-lurbinectedin (M6) in human plasma, were developed and validated. MATERIALS & METHODS: For lurbinectedin, sample extraction was performed using supported liquid extraction. For metabolites, liquid-liquid extraction with stable isotope-labeled analogue internal standards was used. Plasma protein binding was evaluated using rapid equilibrium dialysis. In vitro investigations at different plasma protein concentrations were carried out to estimate dissociation rate constants to albumin and alpha-1-acid glycoprotein (AAG). RESULTS: Calibration curves displayed good linearity over 0.1 to 50 ng/mL for lurbinectedin and 0.5 to 20 ng/mL for the metabolites. Methods were validated in accordance with established guidance. The inter-day precision and accuracy ranged from 5.1% to 10.7%, and from -5% to 6% (lurbinectedin in plasma); from 3.1% to 6.6%, and from 4% to 6% (lurbinectedin in plasma:PBS); from 4.5% to 12.9%, and from 4% to 9% (M4); and from 7.5% to 10.5%, and from 6% to 12% (M6). All methods displayed good linearity (r2 >0.99). Recovery was evaluated for lurbinectedin in plasma:PBS (66.4% to 86.6%), M4 (7.82% to 13.4%) and M6 (22.2% to 34.3%). The method for lurbinectedin in plasma has been applied in most clinical studies, while the plasma:PBS and metabolites methods were used to evaluate the impact of special conditions on lurbinectedin PK. Lurbinectedin plasma protein binding was 99.6% and highly affected by AAG concentration. CONCLUSIONS: These UPLC-MS/MS methods enable the rapid and sensitive quantification of lurbinectedin and its main metabolites in clinical samples.

Trabectedin modulates macrophage polarization in the tumor-microenvironment. Role of KV1.3 and KV1.5 channels.

Immune cells have an important role in the tumor-microenvironment. Macrophages may tune the immune response toward inflammatory or tolerance pathways. Tumor-associated macrophages (TAM) have a string of immunosuppressive functions and they are considered a therapeutic target in cancer. This study aimed to analyze the effects of trabectedin, an antitumor agent, on the tumor-microenvironment through the characterization of the electrophysiological and molecular phenotype of macrophages. Experiments were performed using the whole-cell configuration of the patch-clamp technique in resident peritoneal mouse macrophages. Trabectedin does not directly interact with KV1.5 and KV1.3 channels, but their treatment (16 h) with sub-cytotoxic concentrations of trabectedin increased their KV current due to an upregulation of KV1.3 channels. In vitro generated TAM (TAMiv) exhibited an M2-like phenotype. TAMiv generated a small KV current and express high levels of M2 markers. K+ current from TAMs isolated from tumors generated in mice is a mixture of KV and KCa, and in TAM isolated from tumors generated in trabectedin-treated mice, the current is mostly driven by KCa. We conclude that the antitumor capacity of trabectedin is not only due to its effects on tumor cells, but also to the modulation of the tumor microenvironment, due, at least in part, to the modulation of the expression of different macrophage ion channels.

Plocabulin, a Novel Tubulin Inhibitor, Has Potent Antitumour Activity in Patient-Derived Xenograft Models of Soft Tissue Sarcoma.

A clinically relevant subset of patients with soft tissue sarcoma presents with either locally advanced or upfront metastatic disease, or will develop distant metastases over time, despite successful treatment of their primary tumour. The currently available systemic agents to treat such advanced cases only provide modest disease control and are not active in all histological subtypes. Thus, there is an unmet need for novel and more efficacious agents to improve the outcome of this rare disease. In the current preclinical in vivo study, we evaluated plocabulin, a novel tubulin inhibitor, in five distinct histological subtypes of soft tissue sarcoma: dedifferentiated liposarcoma, leiomyosarcoma, undifferentiated sarcoma, intimal sarcoma and CIC-rearranged sarcoma. The efficacy was tested in seven patient-derived xenograft models, which were generated by the engraftment of tumour fragments from patients directly into nude mice. The treatment lasted 22 days, and the efficacy of the drug was assessed and compared to the doxorubicin and vehicle groups by volumetric analysis, histopathology and immunohistochemistry. We observed tumour volume control in all the tested histological subtypes. Additionally, in three sarcoma subtypes, extensive central necrosis, associated with significant tumour regression, was seen. This histological response is explained by the drug's vascular-disruptive properties, reflected by a decreased total vascular area in the xenografts. Our results demonstrate the in vivo efficacy of plocabulin in the preclinical models of soft tissue sarcoma and corroborate the findings of our previous study, which demonstrated similar vascular-disruptive effects in gastrointestinal stromal tumours-another subtype of soft tissue sarcoma. Our data provide a convincing rationale for further clinical exploration of plocabulin in soft tissue sarcomas.

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.

Preclinical and randomized phase I studies of plitidepsin in adults hospitalized with COVID-19.

Plitidepsin, a marine-derived cyclic-peptide, inhibits SARS-CoV-2 replication at nanomolar concentrations by targeting the host protein eukaryotic translation elongation factor 1A. Here, we show that plitidepsin distributes preferentially to lung over plasma, with similar potency against across several SARS-CoV-2 variants in preclinical studies. Simultaneously, in this randomized, parallel, open-label, proof-of-concept study (NCT04382066) conducted in 10 Spanish hospitals between May and November 2020, 46 adult hospitalized patients with confirmed SARS-CoV-2 infection received either 1.5 mg (n = 15), 2.0 mg (n = 16), or 2.5 mg (n = 15) plitidepsin once daily for 3 d. The primary objective was safety; viral load kinetics, mortality, need for increased respiratory support, and dose selection were secondary end points. One patient withdrew consent before starting procedures; 45 initiated treatment; one withdrew because of hypersensitivity. Two Grade 3 treatment-related adverse events were observed (hypersensitivity and diarrhea). Treatment-related adverse events affecting more than 5% of patients were nausea (42.2%), vomiting (15.6%), and diarrhea (6.7%). Mean viral load reductions from baseline were 1.35, 2.35, 3.25, and 3.85 log10 at days 4, 7, 15, and 31. Nonmechanical invasive ventilation was required in 8 of 44 evaluable patients (16.0%); six patients required intensive care support (13.6%), and three patients (6.7%) died (COVID-19-related). Plitidepsin has a favorable safety profile in patients with COVID-19.

Consensus of the Respiratory Committee of the Latin American Society for Pediatric Intensive Care: Management of pediatric SARS-CoV-2. (SLACIP): COVID-19 Pediatric / Consenso del Comité Respiratorio Sociedad Latinoamericana Terapia Intensiva Pediátrica: Manejo SARS-CoV-2 pediátrico. (SLACIP): COVID-19 Pediátrico

Introduction The COVID-19 pandemic generated many controversies in the management of critically ill pediatric patients. The main ones were about ventilatory support, phenotypic differences between adults and children, and acute and subacute clinical forms. For this reason, the Respiratory Committee (RC) of the Latin American Society of Pediatric Intensive Care (SLACIP) generated a document to summarize the recommendations with the best evidence. The objective of these recommendations is to provide an update on issues related to pediatric COVID-19. Methods and Materials The Respiratory Committee created a group composed of 19 pediatric kinesiologists/physiotherapists and intensivists from 8 Latin American countries and defined on 3/27/20 the 15 most relevant topics, assigning 3 referents and 2 reviewers for each. The manuscripts went through 4 stages until their final version. The complete document was freely distributed on 22/05/20 and updated twice (07/08/20 and 02/09/21). For the current version there were 3 special collaborators. Result The material consists of a complete 94-page document and an executive summary. The topics included are case definition, epidemiology, clinical classification, subacute inflammatory syndrome, personal protective equipment, aerosolization situations (intubation, extubation, suctioning, sampling, filter replacement, cardiopulmonary resuscitation, early mobilization), high flow cannula support, invasive, non-invasive and high frequency mechanical ventilation, pharmacological treatment, laboratory and imaging. Conclusion The purpose of this document is to serve as a guide for nurses, kinesiologists/physiotherapists and physicians in the management of critically ill pediatric patients with COVID-19.

Introducción La pandemia por COVID-19 generó muchas controversias en el manejo de los pacientes pediátricos críticos. Las principales fueron sobre el soporte ventilatorio, las diferencias fenotípicas entre adultos y niños y las formas clínicas aguda y subaguda.Por esa razón el Comité Respiratorio (CR) de la Sociedad Latinoamericana de Cuidados Intensivos Pediátricos (SLACIP) generó un documento para resumir las recomendaciones con mayor evidencia. El objetivo de estas recomendaciones es brindar una actualización de temas relacionados a COVID-19 pediátrico.Métodos y Materiales El Comité Respiratorio creó un grupo compuesto por 19 kinesiólogos/fisioterapeutas y médicos intensivistas pediátricos de 8 países de Latinoamérica y definió el 27/03/20 los 15 temas más relevantes, asignando 3 referentes y 2 revisores por cada uno. Los manuscritos pasaron por 4 etapas hasta su versión final. El documento completo se distribuyó libremente el 22/05/20, actualizándose en dos oportunidades (07/08/20 y el 02/09/21). Para la versión actual se contó con 3 colaboradores especiales.Resultado El material se compone de un documento completo de 94 páginas y un resumen ejecutivo. Los temas incluidos son definición de caso, epidemiología, clasificación clínica, síndrome inflamatorio subagudo, equipos de protección personal, situaciones de aerosolización (intubación, extubación, aspiración, toma de muestras, recambio de filtros, reanimación cardiopulmonar, movilización temprana), soporte con cánula de alto flujo, ventilación mecánica invasiva, no invasiva y de alta frecuencia, tratamiento farmacológico, laboratorio e imágenes.Conclusión La elaboración de este documento ha tenido como fin servir de guía para enfermeros, kinesiólogos/fisioterapeutas y médicos en el manejo de pacientes pediátricos en estado crítico por COVID-19.

Evaluation of the Preclinical Efficacy of Lurbinectedin in Malignant Pleural Mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a highly aggressive cancer generally diagnosed at an advanced stage and characterized by a poor prognosis. The absence of alterations in druggable kinases, together with an immune-suppressive tumor microenvironment, limits the use of molecular targeted therapies, making the treatment of MPM particularly challenging. Here we investigated the in vitro susceptibility of MPM to lurbinectedin (PM01183), a marine-derived drug that recently received accelerated approval by the FDA for the treatment of patients with metastatic small cell lung cancer with disease progression on or after platinum-based chemotherapy. METHODS: A panel of primary MPM cultures, resembling the three major MPM histological subtypes (epithelioid, sarcomatoid, and biphasic), was characterized in terms of BAP1 status and histological markers. Subsequently, we explored the effects of lurbinectedin at nanomolar concentration on cell cycle, cell viability, DNA damage, genotoxic stress response, and proliferation. RESULTS: Stabilized MPM cultures exhibited high sensitivity to lurbinectedin independently from the BAP1 mutational status and histological classification. Specifically, we observed that lurbinectedin rapidly promoted a cell cycle arrest in the S-phase and the activation of the DNA damage response, two conditions that invariably resulted in an irreversible DNA fragmentation, together with strong apoptotic cell death. Moreover, the analysis of long-term treatment indicated that lurbinectedin severely impacts MPM transforming abilities in vitro. CONCLUSION: Overall, our data provide evidence that lurbinectedin exerts a potent antitumoral activity on primary MPM cells, independently from both the histological subtype and BAP1 alteration, suggesting its potential activity in the treatment of MPM patients.

Plitidepsin has a positive therapeutic index in adult patients with COVID-19 requiring hospitalization.

Plitidepsin is a marine-derived cyclic-peptide that inhibits SARS-CoV-2 replication at low nanomolar concentrations by the targeting of host protein eEF1A (eukaryotic translation-elongation-factor-1A). We evaluated a model of intervention with plitidepsin in hospitalized COVID-19 adult patients where three doses were assessed (1.5, 2 and 2.5 mg/day for 3 days, as a 90-minute intravenous infusion) in 45 patients (15 per dose-cohort). Treatment was well tolerated, with only two Grade 3 treatment-related adverse events observed (hypersensitivity and diarrhea). The discharge rates by Days 8 and 15 were 56.8% and 81.8%, respectively, with data sustaining dose-effect. A mean 4.2 log10 viral load reduction was attained by Day 15. Improvement in inflammation markers was also noted in a seemingly dose-dependent manner. These results suggest that plitidepsin impacts the outcome of patients with COVID-19. ONE-SENTENCE SUMMARY: Plitidepsin, an inhibitor of SARS-Cov-2 in vitro , is safe and positively influences the outcome of patients hospitalized with COVID-19.

Plitidepsin has potent preclinical efficacy against SARS-CoV-2 by targeting the host protein eEF1A.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral proteins interact with the eukaryotic translation machinery, and inhibitors of translation have potent antiviral effects. We found that the drug plitidepsin (aplidin), which has limited clinical approval, possesses antiviral activity (90% inhibitory concentration = 0.88 nM) that is more potent than remdesivir against SARS-CoV-2 in vitro by a factor of 27.5, with limited toxicity in cell culture. Through the use of a drug-resistant mutant, we show that the antiviral activity of plitidepsin against SARS-CoV-2 is mediated through inhibition of the known target eEF1A (eukaryotic translation elongation factor 1A). We demonstrate the in vivo efficacy of plitidepsin treatment in two mouse models of SARS-CoV-2 infection with a reduction of viral replication in the lungs by two orders of magnitude using prophylactic treatment. Our results indicate that plitidepsin is a promising therapeutic candidate for COVID-19.

Host-directed therapies against early-lineage SARS-CoV-2 retain efficacy against B.1.1.7 variant.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in millions of deaths worldwide and massive societal and economic burden. Recently, a new variant of SARS-CoV-2, known as B.1.1.7, was first detected in the United Kingdom and is spreading in several other countries, heightening public health concern and raising questions as to the resulting effectiveness of vaccines and therapeutic interventions. We and others previously identified host-directed therapies with antiviral efficacy against SARS-CoV-2 infection. Less prone to the development of therapy resistance, host-directed drugs represent promising therapeutic options to combat emerging viral variants as host genes possess a lower propensity to mutate compared to viral genes. Here, in the first study of the full-length B.1.1.7 variant virus , we find two host-directed drugs, plitidepsin (aplidin; inhibits translation elongation factor eEF1A) and ralimetinib (inhibits p38 MAP kinase cascade), as well as remdesivir, to possess similar antiviral activity against both the early-lineage SARS-CoV-2 and the B.1.1.7 variant, evaluated in both human gastrointestinal and lung epithelial cell lines. We find that plitidepsin is over an order of magnitude more potent than remdesivir against both viruses. These results highlight the importance of continued development of host-directed therapeutics to combat current and future coronavirus variant outbreaks.

Enteritis eosinofílica, una causa extraña de abdomen agudo. reporte de caso clínico / Eosinophilic enteritis, a strange cause of acute abdomen Clinical case report

La enteritis eosinofílica, es una patología rara, caracterizada por infiltración de eosinófilos en una o más capas histológicas en diferentes niveles del tracto gastrointestinal, siendo el estómago e intestino delgado los más afectados; su cuadro clínico, inespecífico, caracterizado por dolor abdominal, náusea, vómito, diarrea o estreñimiento, pérdida de peso y ascitis, con presencia o ausencia de eosinofilia en la biometría. Reporte de caso Paciente masculino de 51 años de edad, acudió a emergencia por distensión abdominal y náusea, al examen físico en la palpación intenso dolor y distención abdominal, percusión timpánico y abolición de ruidos hidroaéreos. La analítica reportó leucocitosis con neutrofilia, radiografía de abdomen íleo adinámico, en la ecografía abdominal presencia de imágenes tubulares con aspecto de diana, asociado a líquido libre purulento en fosa ilíaca derecha y fondo de saco vésico rectal. Un cuadro clínico compatible con abdomen agudo de resolución quirúrgica, se realizó laparotomía exploratoria (AU);

The eosinophilic enteritis is a rare pathology, characterized by infiltration of eosinophils in one or more histological layers at different levels of the gastrointestinal tract, the stomach and small intestine being the most affected; its nonspecific clinical picture, characterized by abdominal pain, nausea, vomiting, diarrhea or constipation, weight loss and ascites, with the presence or absence of eosinophilia in the biometry. Enteritis eosinofílica, una causa extraña de abdomen agudo. reporte de caso clínico Eosinophilic enteritis, a strange cause of acute abdomen year-old male patient came to the emergency room due to abdominal distention and nausea, to physical examination on palpation, intense abdominal pain and distention, tympanic percussion and abolition of air-fluid sounds. Laboratory analysis reported leukocytosis with neutrophilia, abdominal ileus adynamic radiography, abdominal ultrasound presence of tubular images with a target appearance, associated with free purulent fluid in the right iliac fossa and rectal vesicum fundus. A clinical picture compatible with an acute abdomen with surgical resolution, an exploratory laparotomy was performed (AU);

Plocabulin, a novel tubulin inhibitor, has potent antitumor activity in patient-derived xenograft models of gastrointestinal stromal tumors.

The majority of patients with gastrointestinal stromal tumors (GIST) eventually become resistant with time due to secondary mutations in the driver receptor tyrosine kinase. Novel treatments that do not target these receptors may therefore be preferable. For the first time, we evaluated a tubulin inhibitor, plocabulin, in patient-derived xenograft (PDX) models of GIST, a disease generally considered to be resistant to cytotoxic agents. Three PDX models of GIST with different KIT genotype were generated by implanting tumor fragments from patients directly into nude mice. We then used these well characterized models with distinct sensitivity to imatinib to evaluate the efficacy of the novel tubulin inhibitor. The efficacy of the drug was assessed by volumetric analysis of the tumors, histopathology, immunohistochemistry and Western blotting. Plocabulin treatment led to extensive necrosis in all three models and significant tumor shrinkage in two models. This histological response can be explained by the drug's vascular-disruptive properties, which resulted in a shutdown of tumor vasculature, reflected by a decreased total vascular area in the tumor tissue. Our results demonstrated the in vivo efficacy of the novel tubulin inhibitor plocabulin in PDX models of GIST and challenge the established view that GIST are resistant to cytotoxic agents in general and to tubulin inhibitors in particular. Our findings provide a convincing rationale for early clinical exploration of plocabulin in GIST and warrant further exploration of this class of drugs in the management of this common sarcoma subtype.

Caso Clínico: Neurofibromatosis Tipo 1, resolución quirúrgica / Case Report: Neurofibromatos Type 1, Surgical Management

INTRODUCCIÓN: La neurofibromatosis tipo 1(NF1) descrita por primera vez por von Recklinghausen en 1884, es una enfermedad de transmisión genética autosómica dominante, causada por un espectro de mutaciones en el gen NF-1, de evolución impredecible, que afecta múltiples órganos y sistemas, como la piel y el sistema nervioso, afectando también el desarrollo infantil y al estado neurocognitivo. Representa para el médico la toma de decisiones de manejo a menudo complejas, que requieren un enfoque multidisciplinario. CASO CLÍNICO: Paciente femenino de 9 años de edad, con antecedente de neurofibromatosis tipo 1. Presenta masa en región cervical anterior, que ocupa además el hemitórax izquierdo, comprimiendo el mediastino anterior, la tráquea del lado izquierdo, el corazón, el pulmón izquierdo; la masa produce sintomatología: disnea, disfagia y dolor, por lo que se programa intervención quirúrgica para exéresis del tumor. Se realizó cervico-esternotomía- toracotomía izquierda, se extirpó masa de 12 x 7 cm, ubicada a nivel de cayado aórtico, íntimamente adherida a la columna vertebral cervico-torácica. EVOLUCIÓN: Durante el acto quirúrgico la paciente tuvo un sangrado cuantioso, proveniente de arteria colateral de carótida común izquierda, por lo que se decidió empaquetar para resolución posterior, 24 horas después se desempaquetó, logrando control del sangrado tras el procedimiento. Los resultados de anatomía patología establecieron que la masa fue un neurofibroma. El seguimiento posterior determinó mejoría de la sintomatología, sin complicaciones quirúrgicas tardías. CONCLUSIÓN: La Neurofibromatosis es una patología congénita, poco frecuente y de complejo manejo. Aunque no existe tratamiento definitivo para la neurofibromatosis tipo 1, se puede realizar un manejo integral para mejorar la calidad de vida del paciente. Los tumores pueden extirparse mediante cirugía, aunque a menudo vuelven a crecer.(au)

BACKGROUND: Neurofibromatosis type 1, first described by von Recklinghausen in 1884, is an autosomal dominant genetically transmitted disease, caused by a spectrum of mutations in the NF-1 gen, with unpredictable evolution, that affects multiple organs and systems, such as the skin and the nervous system, also affecting child development and neurocognitive functions. It often requires complex management decisions from the physician that involve a multidisciplinary approach. CASE REPORTS: 9 year old female patient with a history of type 1 neurofibromatosis. She presented with a mass located in the anterior cervical region, occupying also the left hemithorax, compressing the anterior mediastinum, the trachea from its left side, the heart, and the left lung; the mass produced symptoms: dyspnea, dysphagia and pain, so surgical excision of the mass was scheduled. A left cervical-sternotomy-thoracotomy was performed, a 12 x 7cm mass, located at aortic arch level, closely adhered to the cervical-thoracic spine, was excised. EVOLUTION: During the surgical procedure, the patient had profuse bleeding, coming form the left common carotid colateral artery, so abdominal packing was performed, for later resolution. 24 hours later, bleeding control was achieved after the surgical re-intervention. The pathology lab results established that the mass was in fact a neurofibroma. Subsequent follow-up determined symptoms improvement, without late surgical complications. CONCLUSIONS: Neurofibromatosis is a congenital infrequent, disease, with a complex treatment. Although there is no definitive treatment for type 1 neurofibromatosis, comprehensive management can be achieved to improve the patient's quality of life. Tumors can be surgically removed, although they often grow back.(au)

CD13 as a new tumor target for antibody-drug conjugates: validation with the conjugate MI130110.

BACKGROUND: In the search for novel antibody-drug conjugates (ADCs) with therapeutic potential, it is imperative to identify novel targets to direct the antibody moiety. CD13 seems an attractive ADC target as it shows a differential pattern of expression in a variety of tumors and cell lines and it is internalized upon engagement with a suitable monoclonal antibody. PM050489 is a marine cytotoxic compound tightly binding tubulin and impairing microtubule dynamics which is currently undergoing clinical trials for solid tumors. METHODS: Anti-CD13 monoclonal antibody (mAb) TEA1/8 has been used to prepare a novel ADC, MI130110, by conjugation to the marine compound PM050489. In vitro and in vivo experiments have been carried out to demonstrate the activity and specificity of MI130110. RESULTS: CD13 is readily internalized upon TEA1/8 mAb binding, and the conjugation with PM050489 did not have any effect on the binding or the internalization of the antibody. MI130110 showed remarkable activity and selectivity in vitro on CD13-expressing tumor cells causing the same effects than those described for PM050489, including cell cycle arrest at G2, mitosis with disarrayed and often multipolar spindles consistent with an arrest at metaphase, and induction of cell death. In contrast, none of these toxic effects were observed in CD13-null cell lines incubated with MI130110. Furthermore, in vivo studies showed that MI130110 exhibited excellent antitumor activity in a CD13-positive fibrosarcoma xenograft murine model, with total remissions in a significant number of the treated animals. Mitotic catastrophes, typical of the payload mechanism of action, were also observed in the tumor cells isolated from mice treated with MI130110. In contrast, MI130110 failed to show any activity in a xenograft mouse model of myeloma cells not expressing CD13, thereby corroborating the selectivity of the ADC to its target and its stability in circulation. CONCLUSION: Our results show that MI130110 ADC combines the antitumor potential of the PM050489 payload with the selectivity of the TEA1/8 monoclonal anti-CD13 antibody and confirm the correct intracellular processing of the ADC. These results demonstrate the suitability of CD13 as a novel ADC target and the effectiveness of MI130110 as a promising antitumor therapeutic agent.

Generation of endoplasmic reticulum stress and inhibition of autophagy by plitidepsin induces proteotoxic apoptosis in cancer cells.

Plitidepsin (PLD, Aplidin®), a cyclic depsipeptide originally isolated from the marine tunicate Aplidium albicans, has been recently approved by Australian regulatory authorities for the treatment of multiple myeloma patients. Plitidepsin binds to eEF1A2 and induces oxidative stress, Rac1 activation and JNK1 phosphorylation, triggering a rapid apoptotic program in tumor cells. Since oxidative stress is one of the known sources of endoplasmic reticulum stress, we investigated whether PLD was inducing a bona fide ER stress in HeLa cells and whether this process was essential in the mechanism of action of the compound. Indeed, PLD activated an ER stress-induced unfolded protein response (UPR), including the alternative splicing of XBP1, the proteolytic processing of ATF6 and the phosphorylation of eIF2α and JNK. Interestingly, though PLD induced a strong phosphorylation of eIF2α in all the analyzed cell lines, it did not elicit an increased expression of ATF4 and CHOP, a transcription factor involved in launching UPR-mediated apoptosis. On the contrary, a clear reduction of CHOP protein levels was observed after PLD treatment, most probably due to both the lack of transactivation by ATF4 and its rapid degradation by the ubiquitin/proteasome machinery. Using fibroblasts devoid of each one of the four possible kinases involved in eIF2α phosphorylation, we observed that only PKR was involved in the response to PLD treatment and, accordingly, PKR-/- fibroblasts are shown to be resistant to the apoptogenic activity of the compound. Furthermore, eIF2α phosphorylation itself was shown to be irrelevant for the induction of cell death by PLD. Instead, we reveal that PLD induces an increase in the levels of misfolded proteins while simultaneously inhibiting the autophagic flux. These two effects combined prevent PLD-treated cells from reducing proteotoxic stress and lead to apoptosis. Other anti-myeloma drugs like bortezomib, which target the proteasome, also inhibit the degradation of misfolded proteins through alternate pathways and a synergistic anticancer effect of the PLD plus bortezomib combination has been previously disclosed. The present results extend this synergy to in vivo experiments and provide a mechanistic rationale for this synergy.

MI130004, a Novel Antibody-Drug Conjugate Combining Trastuzumab with a Molecule of Marine Origin, Shows Outstanding In Vivo Activity against HER2-Expressing Tumors.

In the search for novel payloads to design new antibody-drug conjugates (ADC), marine compounds represent an interesting opportunity given their unique chemical features. PM050489 is a marine compound that binds ß-tubulin at a new site and disrupts the microtubule network, hence leading to mitotic aberrations and cell death. PM050489 has been conjugated to trastuzumab via Cys residues through a noncleavable linker, and the resulting ADC, named MI130004, has been studied. Analysis of MI130004 delivered data consistent with the presence of two molecules of PM050489 per antibody molecule, likely bound to both sides of the intermolecular disulfide bond connecting the antibody light and heavy chains. The antitumor activity of MI130004 was analyzed in vitro and in vivo in different cell lines of diverse tumor origin (breast, ovary, and gastric cancer) expressing different levels of HER2. MI130004 showed very high in vitro potency and good selectivity for tumor cells that overexpressed HER2. At the cellular level, MI130004 impaired tubulin polymerization, causing disorganization and disintegration of the microtubule network, which ultimately led to mitotic failure, mirroring the effect of its payload. Treatment with MI130004 in mice carrying histologically diverse tumors expressing HER2 induced a long-lasting antitumor effect with statistically significant inhibition of tumor growth coupled with increases in median survival time compared with vehicle or trastuzumab. These results strongly suggest that MI130004 is endowed with remarkable anticancer activity and confirm the extraordinary potential of marine compounds for the design of new ADCs. Mol Cancer Ther; 17(4); 786-94. ©2018 AACR.

Plocabulin, a novel tubulin-binding agent, inhibits angiogenesis by modulation of microtubule dynamics in endothelial cells.

BACKGROUND: Vascular supply of tumors is one of the main targets for cancer therapy. Here, we investigated if plocabulin (PM060184), a novel marine-derived microtubule-binding agent, presents antiangiogenic and vascular-disrupting activities. METHODS: The effects of plocabulin on microtubule network and dynamics were studied on HUVEC endothelial cells. We have also studied its effects on capillary tube structures formation or destabilization in three-dimensional collagen matrices. In vivo experiments were performed on different tumor cell lines. RESULTS: In vitro studies show that, at picomolar concentrations, plocabulin inhibits microtubule dynamics in endothelial cells. This subsequently disturbs the microtubule network inducing changes in endothelial cell morphology and causing the collapse of angiogenic vessels, or the suppression of the angiogenic process by inhibiting the migration and invasion abilities of endothelial cells. This rapid collapse of the endothelial tubular network in vitro occurs in a concentration-dependent manner and is observed at concentrations lower than that affecting cell survival. The in vitro findings were confirmed in tumor xenografts where plocabulin treatment induced a large reduction in vascular volume and induction of extensive necrosis in tumors, consistent with antivascular effects. CONCLUSIONS: Altogether, these data suggest that an antivascular mechanism is contributing to the antitumor activities of plocabulin.

Improved pharmacokinetic profile of lipophilic anti-cancer drugs using ανß3-targeted polyurethane-polyurea nanoparticles.

Glutathione degradable polyurethane-polyurea nanoparticles (PUUa NP) with a disulfide-rich multiwalled structure and a cyclic RGD peptide as a targeting moiety were synthesized, incorporating a very lipophilic chemotherapeutic drug named Plitidepsin. In vitro studies indicated that encapsulated drug maintained and even improved its cytotoxic activity while in vivo toxicity studies revealed that the maximum tolerated dose (MTD) of Plitidepsin could be increased three-fold after encapsulation. We also found that pharmacokinetic parameters such as maximum concentration (Cmax), area under the curve (AUC) and plasma half-life were significantly improved for Plitidepsin loaded in PUUa NP. Moreover, biodistribution assays in mice showed that RGD-decorated PUUa NP accumulate less in spleen and liver than non-targeted conjugates, suggesting that RGD-decorated nanoparticles avoid sequestration by macrophages from the reticuloendothelial system. Overall, our results indicate that polyurethane-polyurea nanoparticles represent a very valuable nanoplatform for the delivery of lipophilic drugs by improving their toxicological, pharmacokinetic and whole-body biodistribution profiles.