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The use of Digital Healthcare Products is leading to significant improvements in clinical practice. Herein, we discuss the development of PROACT 2.0 (Patient Reported Opinions About Clinical Tolerability v2.0), a novel open-source mobile and web application developed at Fondazione IRCCS Istituto Nazionale Tumori in Milan. It was developed in collaboration with The Christie, Manchester, in the context of work package 2 of the UpSMART Accelerator project, involving a consortium of referral cancer centers from the UK, Spain and Italy. PROACT 2.0 enhances communication between patients and healthcare providers in cancer clinical trials, allowing patients to report adverse events and side effects, and healthcare teams to collect valuable patient-reported outcome measures for treatment management. PROACT 2.0 supports text, audio, and video messaging, offering a secure, non-urgent communication channel that integrates with, or replaces, traditional methods. Its user-friendly and multilingual interface provides a new route for patient engagement and streamlines the handling of logistical information. Positive feedback from initial testing warrants future enhancements for broader applicability in cancer research and treatment.
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In patients with advanced triple-negative breast cancer (TNBC), translational research efforts are needed to improve the clinical efficacy of immunotherapy with checkpoint inhibitors. Here, we report on the immunological characterization of an exceptional, long-lasting, tumor complete response in a patient with metastatic TNBC treated with dual PD-1 and LAG-3 blockade within the phase I/II study CLAG525X2101C (NCT02460224) The pre-treatment tumor biopsy revealed the presence of a CD3+ and CD8+ cell infiltrate, with few PD1+ cells, rare CD4+ cells, and an absence of both NK cells and LAG3 expression. Conversely, tumor cells exhibited positive staining for the three primary LAG-3 ligands (HLA-DR, FGL-1, and galectin-3), while being negative for PD-L1. In peripheral blood, baseline expression of LAG-3 and PD-1 was observed in circulating immune cells. Following treatment initiation, there was a rapid increase in proliferating granzyme-B+ NK and T cells, including CD4+ T cells, alongside a reduction in myeloid-derived suppressor cells. The role of LAG-3 expression on circulating NK cells, as well as the expression of LAG-3 ligands on tumor cells and the early modulation of circulating cytotoxic CD4+ T cells warrant further investigation as exploitable predictive biomarkers for dual PD-1 and LAG-3 blockade.Trial registration: NCT02460224. Registered 02/06/2015.
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Antineoplásicos , Neoplasias de Mama Triplo Negativas , Humanos , Neoplasias de Mama Triplo Negativas/patologia , Receptor de Morte Celular Programada 1/metabolismo , Antineoplásicos/uso terapêutico , Linfócitos T CD8-Positivos , Resultado do Tratamento , Antígeno B7-H1RESUMO
PURPOSE: The investigation of multiple molecular targets with next-generation sequencing (NGS) has entered clinical practice in oncology, yielding to a paradigm shift from the histology-centric approach to the mutational model for personalized treatment. Accordingly, most of the drugs recently approved in oncology are coupled to specific biomarkers. One potential tool for implementing the mutational model of precision oncology in daily practice is represented by the Molecular Tumor Board (MTB), a multidisciplinary team whereby molecular pathologists, biologists, bioinformaticians, geneticists, medical oncologists, and pharmacists cooperate to generate, interpret, and match molecular data with personalized treatments. PATIENTS AND METHODS: Since May 2020, the institutional MTB set at Fondazione IRCCS Istituto Nazionale Tumori of Milan met weekly via teleconference to discuss molecular data and potential therapeutic options for patients with advanced/metastatic solid tumors. RESULTS: Up to October 2021, among 1,996 patients evaluated, we identified >10,000 variants, 43.2% of which were functionally relevant (pathogenic or likely pathogenic). On the basis of functionally relevant variants, 711 patients (35.6%) were potentially eligible to targeted therapy according to European Society of Medical Oncology Scale for Clinical Actionability of Molecular Targets tiers, and 9.4% received a personalized treatment. Overall, larger NGS panels (containing >50 genes) significantly outperformed small panels (up to 50 genes) in detecting actionable gene targets across different tumor types. CONCLUSION: Our real-world data provide evidence that MTB is a valuable tool for matching NGS data with targeted treatments, eventually implementing precision oncology in clinical practice.
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Neoplasias , Humanos , Medicina de Precisão , Assistência ao Paciente , Oncologia , Sequenciamento de Nucleotídeos em Larga EscalaRESUMO
Aim: Diagnostic laboratories are progressively introducing next-generation sequencing (NGS) technologies in the routine workflow to meet the increasing clinical need for comprehensive molecular characterization in cancer patients for diagnosis and precision medicine, including fusion-transcripts detection. Nevertheless, the low quality of messenger RNA (mRNA) extracted from formalin-fixed paraffin-embedded (FFPE) samples may affect the transition from traditional single-gene testing approaches [like fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), or polymerase chain reaction (PCR)] to NGS. The present study is aimed at assessing the overall accuracy of RNA fusion transcripts detection by NGS analysis in FFPE samples in real-world diagnostics. Methods: Herein, NGS data from 190 soft tissue tumors (STTs) and carcinoma cases, discussed in the context of the institutional Molecular Tumor Board, are reported and analyzed by FusionPlex© Solid tumor kit through the manufacturer's pipeline and by two well-known fast and accurate open-source tools [Arriba (ARR) and spliced transcripts alignment to reference (STAR)-fusion (SFU)]. Results: The combination of FusionPlex© Solid tumor with ArcherDX® Analysis suite (ADx) analysis package has been proven to be sensitive and specific in STT samples, while partial loss of sensitivity has been found in carcinoma specimens. Conclusions: Albeit ARR and SFU showed lower sensitivity, the use of additional fusion-detection tools can contribute to reinforcing or extending the output obtained by ADx, particularly in the case of low-quality input data. Overall, our results sustain the clinical use of NGS for the detection of fusion transcripts in FFPE material.
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Background: Systemic immunosuppression characterizing cancer patients represents a concern regarding the efficacy of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, and real-world evidence is needed to define the efficacy and the dynamics of humoral immune response to mRNA-based anti-SARS-CoV-2 vaccines. Methods: We conducted an observational study that included patients with solid tumors who were candidates for mRNA anti-SARS-CoV-2 vaccination at the Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy. The primary objective was to monitor the immunologic response to the mRNA anti-SARS-CoV-2 vaccination in terms of anti-spike antibody levels. All the patients received two doses of the mRNA-1273 vaccine or the BNT162b2 vaccine. Healthcare workers served as a control group of healthy subjects. Results: Among the 243 patients included in the present analysis, 208 (85.60%) and 238 (97.94%) resulted seroconverted after the first and the second dose of vaccine, respectively. Only five patients (2.06%) had a negative titer after the second dose. No significant differences in the rate of seroconversion after two vaccine doses were observed in patients as compared with the control group of healthy subjects. Age and anticancer treatment class had an independent impact on the antibody titer after the second dose of vaccination. In a subgroup of 171 patients with available data about the third timepoint, patients receiving immunotherapy with immune checkpoint inhibitors seem to have a higher peak of antibodies soon after the second dose (3 weeks after), but a more pronounced decrease at a late timepoint (3 months after). Conclusions: The systemic immunosuppression characterizing cancer patients did not seem to dramatically affect the humoral response to anti-SARS-CoV-2 mRNA vaccines in our population of patients with solid tumors. Further investigation is needed to dissect the interplay between immunotherapy and longitudinal dynamics of humoral response to mRNA vaccines, as well as to analyze the cellular response to mRNA vaccines in cancer patients.
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Tumour testing of the BRCA1/2 genes is routinely performed in patients with different cancer histological subtypes. To accurately identify patients with tumour-detected germline pathogenic variants (PVs) is a relevant issue currently under investigation. This study aims at evaluating the performance of the tumour-to-germline diagnostic flowchart model defined at our Institutional Molecular Tumour Board (MTB). Results from tumour BRCA sequencing of 641 consecutive unselected cancer patients were discussed during weekly MTB meetings with the early involvement of clinical geneticists for appropriate referral to genetic counselling. The overall tumour detection rate of BRCA1/2 PVs was 8.7% (56/641), ranging from 24.4% (31/127) in high-grade ovarian cancer to 3.9% (12/304) in tumours not associated with germline BRCA1/2 PVs. Thirty-seven patients with PVs (66%) were evaluated by a clinical geneticist, and in 24 of them (64.9%), germline testing confirmed the presence of the PV in blood. Nine of these patients (37.5%) were not eligible for germline testing according to the criteria in use at our institution. Cascade testing was subsequently performed on 18 relatives. The tumour-to-germline diagnostic pipeline, developed in the framework of our institutional MTB, compared with guideline-based germline testing following genetic counselling, proved to be effective in identifying a higher number of germline BRCA PVs carriers.
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This first-in-human (FIH), phase I, multicenter, open-label study was conducted to characterize the safety, tolerability, pharmacokinetics, and preliminary efficacy, and to establish the MTD/recommended dose for expansion (RDE) of PCA062 in patients with solid tumors. Adult patients with any solid tumor type and having a documented P-cadherin-positive tumor were enrolled; exceptions to P-cadherin positivity requirement were head and neck squamous cell carcinomas (HNSCC) and esophageal squamous cell carcinoma (ESCC). Dose escalation was guided by an adaptive Bayesian logistic regression model with escalation with overdose control to determine the MTD/RDE. Forty-seven patients were treated at 10 different dose levels of PCA062, ranging from 0.4 to 5.0 mg/kg every 2 weeks administered as a 1-hour intravenous infusion. All enrolled patients discontinued the treatment; primary reason for discontinuation was progressive disease (78.7%). All 47 patients experienced at least one AE, of which 32 patients had a grade ≥3 AE and 37 patients experienced AEs suspected to be study drug related. The MTD of PCA062 was 3.6 mg/kg every 2 weeks and thrombocytopenia was reported as a DLT that was attributed to the known toxicities of the DM1 payload with no P-cadherin-related toxicities. Pharmacokinetics was proportional, and no patients developed antidrug antibodies, suggesting adequate exposure at the doses tested. One patient of 47 achieved a partial response and there was no correlation between tumor P-cadherin expression and clinical efficacy. Because of limited antitumor activity at the MTD level, Novartis has terminated clinical development of PCA062 (NCT02375958).
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Neoplasias Esofágicas , Carcinoma de Células Escamosas do Esôfago , Neoplasias de Cabeça e Pescoço , Imunoconjugados , Neoplasias , Adulto , Teorema de Bayes , Caderinas , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Humanos , Imunoconjugados/uso terapêutico , Dose Máxima Tolerável , Neoplasias/patologiaRESUMO
In the era of precision medicine, monoclonal antibodies and small molecule inhibitors are the mainstays of the biological therapy in patients with solid tumors. However, resistance to treatment and the "undruggability" of certain key oncogenic proteins emerged as major limitations and jeopardize the clinical benefit of modern therapeutic approaches. Targeted protein degraders are novel molecules entering the early phase of clinical development that exploit the intracellular ubiquitine-proteasome system to promote a specific degradation of target proteins. Since the peculiar mechanism of action, targeted protein degraders have the potential to limit and overcome resistance to treatment and to allow a full actionability of certain cancer drivers that are actually elusive targets. Here, we discuss the state-of-the-art and the open issues in the development of these emerging biological agents from a clinical perspective and with a focus on solid tumors.
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Neoplasias , Oncologistas , Humanos , Neoplasias/tratamento farmacológico , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas/metabolismo , ProteóliseRESUMO
PURPOSE: To assess the safety and tolerability of BMS-986148, a mesothelin-directed antibody-drug conjugate (ADC) ± nivolumab, in patients with selected tumors. PATIENTS AND METHODS: In an international phase I/IIa study [NCT02341625 (CA008-002)], patients received BMS-986148 monotherapy (0.1-1.6 mg/kg intravenously (i.v.) every 3 weeks or 0.4 or 0.6 mg/kg i.v. once weekly; n = 96) or BMS-986148 0.8 mg/kg + nivolumab 360 mg i.v. every 3 weeks (n = 30). The primary endpoint was safety and tolerability. RESULTS: In CA008-002, the most common (≥ 10%) treatment-related adverse events (TRAEs) included increased aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Grade 3/4 TRAEs occurred in 42 patients (49%) receiving BMS-986148 every 3 weeks monotherapy, three (25%) receiving BMS-986148 once-weekly monotherapy, and 10 (33%) receiving BMS-986148 + nivolumab every 3 weeks. Overall, 17 of 126 patients (13%) discontinued because of a TRAE. The MTD of BMS-986148 was 1.2 mg/kg i.v. every 3 weeks. The safety profile of BMS-986148 + nivolumab was similar to that of BMS-986148 monotherapy (0.8 mg/kg). Active ADC exposures increased in a dose-proportional manner with both dosing regimens (every 3 weeks and once weekly). Preliminary clinical activity was observed with BMS-986148 ± nivolumab. No association between mesothelin expression and response was detected. CONCLUSIONS: BMS-986148 ± nivolumab demonstrated a clinically manageable safety profile and preliminary evidence of clinical activity, supporting additional studies combining directed cytotoxic therapies with checkpoint inhibitors as potential multimodal therapeutic strategies in patients with advanced solid tumors.
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Protocolos de Quimioterapia Combinada Antineoplásica , Imunoconjugados , Neoplasias , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Humanos , Imunoconjugados/efeitos adversos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Nivolumabe/uso terapêuticoRESUMO
This phase 1 trial (NCT01938846) determined the maximum tolerated dose (MTD) of the mTOR serine/threonine kinase inhibitor, BI 860585, as monotherapy and with exemestane or paclitaxel in patients with advanced solid tumors. This 3+3 dose-escalation study assessed BI 860585 monotherapy (5-300 mg/day; Arm A), BI 860585 (40-220 mg/day; Arm B) with 25 mg/day exemestane, and BI 860585 (80-220 mg/day; Arm C) with 60-80 mg/m2/week paclitaxel, in 28-day cycles. Primary endpoints were the number of patients with dose-limiting toxicities (DLTs) in cycle 1 and the MTD. Forty-one, 25, and 24 patients were treated (Arms A, B, and C). DLTs were observed in four (rash (n = 2), elevated alanine aminotransferase/aspartate aminotransferase, diarrhea), four (rash (n = 3), stomatitis, and increased gamma-glutamyl transferase), and two (diarrhea, increased blood creatine phosphokinase) patients in cycle 1. The BI 860585 MTD was 220 mg/day (Arm A) and 160 mg/day (Arms B and C). Nine patients achieved an objective response (Arm B: Four partial responses (PRs); Arm C: Four PRs; one complete response). The disease control rate was 20%, 28%, and 58% (Arms A, B, and C). The most frequent treatment-related adverse events (AEs) were hyperglycemia (54%) and diarrhea (39%) (Arm A); diarrhea (40%) and stomatitis (40%) (Arm B); fatigue (58%) and diarrhea (58%) (Arm C). The MTD was determined in all arms. Antitumor activity was observed with BI 860585 monotherapy and in combination with exemestane or paclitaxel.
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The efficacy of anthracycline- and taxane-based chemotherapy for perioperative treatment of breast cancer (BC) has been established. No superiority of a cytotoxic regimen has been demonstrated, provided that administration of an anthracycline and a taxane is warranted. The ASTER study was designed to investigate the safety of 6 months of perioperative chemotherapy with Doxorubicin and Paclitaxel, followed by Cyclophosphamide, Methotrexate, and 5-Fluorouracil. ASTER enrolled patients with cT2-3 N0-1 or pT1-2 N1-3 BC, from November 2008 to August 2011. Treatment consisted of Doxorubicin 60 mg/sm, Paclitaxel 200 mg/sm q21 (AT) for three cycles followed by Cyclophosphamide 600 mg/sm, Methotrexate 40 mg/sm, 5-Fluorouracil 600 mg/sm d1,8 q28 (CMF) for three cycles, in either neo-adjuvant or adjuvant setting. All HER-positive patients received targeted therapy with Trastuzumab for 1 year. Disease-free and overall survival (DFS and OS, respectively) were estimated according to Kaplan-Meier method. Three hundred and thirty patients were enrolled, where 77.9% of cases were treated in an adjuvant setting; 65.5% received breast conservative surgery, 72.4% axillary dissection. 75.5% of cases presented estrogen receptor positivity, 66.7% progesterone receptor positivity; 18.5% of patients presented HER2-positive BC, 16.1% triple negative disease. Twenty-eight (8.5%) developed grade III-IV hematologic toxicity; nine patients (2.7%) developed grade III neurological toxicity. Loco-regional DFS was 99.6% at 1 year, 97.1% at 5 years, 95.9% at 7 years. Corresponding distant DFS was 98.4%, 90.2%, and 88.8%. One, 5, and 7-year OS was 99.6%, 94.9%, and 91.2%, respectively. Chemotherapy with ATx3âCMFx3 is confirmed safe and effective at 6.7 years follow-up. These results appear comparable to those reported in regulatory trials of most commonly prescribed anthracycline and taxane-based regimens.
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Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/cirurgia , Adulto , Idoso , Antraciclinas/administração & dosagem , Neoplasias da Mama/mortalidade , Ciclofosfamida/administração & dosagem , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Seguimentos , Humanos , Pessoa de Meia-Idade , Taxoides/administração & dosagemRESUMO
OBJECTIVES: Cancer Testis Antigens are immunogenic tumor-specific proteins. We investigated NY-ESO-1, MAGE-A3 and PRAME, in addition to WT1 expression in different Breast Cancer (BC) subtypes. We then evaluated the expression rate of NY-ESO-1 in early Triple Negative breast cancer (TNBC), and investigated whether its expression would be maintained or lost in the metastatic setting to explore possible immunotherapy indication. MATERIALS AND METHODS: Three subgroups of BC patients were selected by the expression of ER, PgR and Her2. Tissue microarray was performed on a total of 92 Invasive BC. Sections were stained for NY-ESO-1, MAGE-A3, PRAME and WT1. The second cohort was composed by 26 metastatic TNBC patients from whom both the primary and secondary lesion tissues were available. Sections were stained for NY-ESO-1. RESULTS: NY-ESO-1 was the only differentially expressed antigen and was absent in ER+ and ER-PgR + tumors, as for an exclusive expression of either NY-ESO-1 or at least one hormonal receptor (HR+). NY-ESO-1 was particularly represented in TNBC. No correlation has been found between MAGE-A3 and PRAME expression and subtype WT1 had low expression, except in the Her2+ group. In the second cohort, NY-ESO-1 was expressed in 12 and 24% of primary and metastatic lesions respectively. CONCLUSIONS: This study defines a distinction between HR+ and HR-tumors through NY-ESO-1 expression. TNBC subgroup has the highest frequency of NY-ESO-1+ cases, and it could be the candidate population for the development of anti-NY-ESO-1 vaccine, both in the adjuvant or metastatic setting, and for the selection of cases suitable for immunotherapy.
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Antígenos de Neoplasias/metabolismo , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/metabolismo , Antígenos Específicos de Melanoma/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas WT1/metabolismo , Adulto , Neoplasias da Mama/terapia , Estudos de Coortes , Feminino , Humanos , Técnicas Imunoenzimáticas , Pessoa de Meia-Idade , Estadiamento de NeoplasiasRESUMO
Entrectinib, a potent oral inhibitor of the tyrosine kinases TRKA/B/C, ROS1, and ALK, was evaluated in two phase I studies in patients with advanced or metastatic solid tumors, including patients with active central nervous system (CNS) disease. Here, we summarize the overall safety and report the antitumor activity of entrectinib in a cohort of patients with tumors harboring NTRK1/2/3, ROS1, or ALK gene fusions, naïve to prior TKI treatment targeting the specific gene, and who were treated at doses that achieved therapeutic exposures consistent with the recommended phase II dose. Entrectinib was well tolerated, with predominantly Grades 1/2 adverse events that were reversible with dose modification. Responses were observed in non-small cell lung cancer, colorectal cancer, mammary analogue secretory carcinoma, melanoma, and renal cell carcinoma, as early as 4 weeks after starting treatment and lasting as long as >2 years. Notably, a complete CNS response was achieved in a patient with SQSTM1-NTRK1-rearranged lung cancer.Significance: Gene fusions of NTRK1/2/3, ROS1, and ALK (encoding TRKA/B/C, ROS1, and ALK, respectively) lead to constitutive activation of oncogenic pathways. Entrectinib was shown to be well tolerated and active against those gene fusions in solid tumors, including in patients with primary or secondary CNS disease. Cancer Discov; 7(4); 400-9. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 339.
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Benzamidas/administração & dosagem , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Colorretais/tratamento farmacológico , Indazóis/administração & dosagem , Carcinoma Secretor Análogo ao Mamário/tratamento farmacológico , Melanoma/tratamento farmacológico , Proteínas de Fusão Oncogênica/antagonistas & inibidores , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Quinase do Linfoma Anaplásico , Benzamidas/efeitos adversos , Benzamidas/farmacocinética , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Crizotinibe , Relação Dose-Resposta a Droga , Feminino , Humanos , Indazóis/efeitos adversos , Indazóis/farmacocinética , Masculino , Carcinoma Secretor Análogo ao Mamário/genética , Melanoma/genética , Melanoma/patologia , Glicoproteínas de Membrana/antagonistas & inibidores , Glicoproteínas de Membrana/genética , Pessoa de Meia-Idade , Proteínas de Fusão Oncogênica/genética , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/farmacocinética , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Pirazóis/administração & dosagem , Piridinas/administração & dosagem , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/genética , Receptor trkA/antagonistas & inibidores , Receptor trkA/genética , Receptor trkB/antagonistas & inibidores , Receptor trkB/genética , Receptor trkC/antagonistas & inibidores , Receptor trkC/genética , Proteína Sequestossoma-1/genéticaRESUMO
Thoracic splenosis (TS) is a condition of autotransplantation of splenic tissue into the pleural cavity after thoraco-abdominal trauma, with diaphragmatic and spleen injury. It is usually asymptomatic and discovered as an incidental finding at imaging performed for other reasons. Its differential diagnosis regards different benign and malignant conditions and should be discerned avoiding invasive procedures. We report a case of thoracic mass associated with pleural nodules mimicking malignancy in a patient with resected breast cancer for whom a diagnosis of TS was made early by using non-invasive methods. Briefly, we review the literature data on TS, comment concisely the possible implications of using invasive procedures and describe the current non-invasive techniques available. Furthermore, we highlight the importance of an accurate medical history collection, the role of the multidisciplinary board and their impact on treatment decision making. Finally, we conclude that clinical information and imaging would be the discriminating factors to avoid unnecessary invasive procedures.
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Using de novo protein design, we incorporated a copper metal binding site within the three-helix bundle α3D (Walsh et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5486-5491) to assess whether a cupredoxin center within an α-helical domain could mimic the spectroscopic, structural, and redox features of native type-1 copper (CuT1) proteins. We aimed to determine whether a CuT1 center could be realized in a markedly different scaffold rather than the native ß-barrel fold and whether the characteristic short Cu-S bond (2.1-2.2 Å) and positive reduction potentials could be decoupled from the spectroscopic properties (ε600 nm = 5000 M(-1) cm(-1)) of such centers. We incorporated 2HisCys(Met) residues in three distinct α3D designs designated core (CR), chelate (CH), and chelate-core (ChC). XAS analysis revealed a coordination environment similar to reduced CuT1 proteins, producing Cu-S(Cys) bonds ranging from 2.16 to 2.23 Å and Cu-N(His) bond distances of 1.92-1.99 Å. However, Cu(II) binding to the CR and CH constructs resulted in tetragonal type-2 copper-like species, displaying an intense absorption band between 380 and 400 nm (>1500 M(-1) cm(-1)) and A|| values of (150-185) × 10(-4) cm(-4). The ChC construct, which possesses a metal-binding site deeper in its helical bundle, yielded a CuT1-like brown copper species, with two absorption bands at 401 (4429 M(-1) cm(-1)) and 499 (2020 M(-1) cm(-1)) nm and an A|| value â¼30 × 10(-4) cm(-4) greater than its native counterparts. Electrochemical studies demonstrated reduction potentials of +360 to +460 mV (vs NHE), which are within the observed range for azurin and plastocyanin. These observations showed that the designed metal binding sites lacked the necessary rigidity to enforce the appropriate structural constraints for a Cu(II) chromophore (EPR and UV-vis); however, the Cu(I) structural environment and the high positive potential of CuT1 centers were recapitulated within the α-helical bundle of α3D.
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Azurina/química , Cobre/química , Metaloproteínas/química , Sítios de Ligação , Técnicas Eletroquímicas , Espectroscopia de Ressonância Magnética , Metaloproteínas/isolamento & purificação , Modelos MolecularesRESUMO
From a study of the electrocatalytic reduction of nitrate on Pt and Rh electrodes over a wide pH range, HNO3 is suggested as the only reducible species in nitrate reduction on Pt, whereas both HNO3 and the nitrate anion are reducible on Rh. Rh is the more active catalyst of the two because it can activate nitrate even if no protons are available in solution. This is an important insight into the development of more effective nitrate reduction catalysts.