Background Convalescent plasma (CP), despite limited evidence on its efficacy, is being widely used as a compassionate therapy for hospitalized patients with COVID-19. We aimed to evaluate the efficacy and safety of early CP therapy in COVID-19 progression. Methods and findings The study was an open-label, single-center randomized clinical trial performed in an academic medical center in Santiago, Chile, from May 10, 2020, to July 18, 2020, with final follow-up until August 17, 2020. The trial included patients hospitalized within the first 7 days of COVID-19 symptom onset, presenting risk factors for illness progression and not on mechanical ventilation. The intervention consisted of immediate CP (early plasma group) versus no CP unless developing prespecified criteria of deterioration (deferred plasma group). Additional standard treatment was allowed in both arms. The primary outcome was a composite of mechanical ventilation, hospitalization for >14 days, or death. The key secondary outcomes included time to respiratory failure, days of mechanical ventilation, hospital length of stay, mortality at 30 days, and SARS-CoV-2 real-time PCR clearance rate. Of 58 randomized patients (mean age, 65.8 years; 50% male), 57 (98.3%) completed the trial. A total of 13 (43.3%) participants from the deferred group received plasma based on clinical aggravation. We failed to find benefit in the primary outcome (32.1% versus 33.3%, odds ratio [OR] 0.95, 95% CI 0.32–2.84, p > 0.999) in the early versus deferred CP group. The in-hospital mortality rate was 17.9% versus 6.7% (OR 3.04, 95% CI 0.54–17.17 p = 0.246), mechanical ventilation 17.9% versus 6.7% (OR 3.04, 95% CI 0.54–17.17, p = 0.246), and prolonged hospitalization 21.4% versus 30.0% (OR 0.64, 95% CI, 0.19–2.10, p = 0.554) in the early versus deferred CP group, respectively. The viral clearance rate on day 3 (26% versus 8%, p = 0.204) and day 7 (38% versus 19%, p = 0.374) did not differ between groups. Two patients experienced serious adverse events within 6 hours after plasma transfusion. The main limitation of this study is the lack of statistical power to detect a smaller but clinically relevant therapeutic effect of CP, as well as not having confirmed neutralizing antibodies in donor before plasma infusion. Conclusions In the present study, we failed to find evidence of benefit in mortality, length of hospitalization, or mechanical ventilation requirement by immediate addition of CP therapy in the early stages of COVID-19 compared to its use only in case of patient deterioration. Trial registration NCT04375098.

Thyroid cancer is the most frequent endocrine malignancy, and its incidence is increasing. A current limitation of cytological evaluation of thyroid nodules is that 20–25% are reported as indeterminate. Therefore, an important challenge for clinicians is to determine whether an indeterminate nodule is malignant, and should undergo surgery, or benign, and should be recommended to follow-up. The emergence of precision medicine has offered a valuable solution for this problem, with four tests currently available for the molecular diagnosis of indeterminate cytologies. However, efforts to critically analyze the quality of the accumulated evidence are scarce. This systematic review and meta-analysis is aimed to contribute to a better knowledge about the four available molecular tests, their technical characteristics, clinical performance, and ultimately to help clinicians to make better decisions to provide the best care options possible. For this purpose, we address three critical topics: (i) the proper theoretical accuracy, considering the intended clinical use of the test (rule-in vs rule-out) and the impact on clinical decisions; (ii) the quality of the evidence reported for each test (iii) and how accurate and effective have the tests proved to be after their clinical use. Together with the upcoming evidence, this work provides significant and useful information for healthcare system decision-makers to consider the use of molecular testing as a public health need, avoiding unnecessary surgical risks and costs.

Background: In most of the world, diagnostic surgery remains the most frequent approach for indeterminate thyroid cytology. Although several molecular tests are available for testing in centralized commercial laboratories in the United States, there are no available kits for local laboratory testing. The aim of this study was to develop a prototype in vitro diagnostic (IVD) gene classifier for the further characterization of nodules with an indeterminate thyroid cytology.Methods: In a first stage, the expression of 18 genes was determined by quantitative polymerase chain reaction (qPCR) in a broad histopathological spectrum of 114 fresh-tissue biopsies. Expression data were used to train several classifiers by supervised machine learning approaches. Classifiers were tested in an independent set of 139 samples. In a second stage, the best classifier was chosen as a model to develop a multiplexed-qPCR IVD prototype assay, which was tested in a prospective multicenter cohort of fine-needle aspiration biopsies.Results: In tissue biopsies, the best classifier, using only 10 genes, reached an optimal and consistent performance in the ninefold cross-validated testing set (sensitivity 93% and specificity 81%). In the multicenter cohort of fine-needle aspiration biopsy samples, the 10-gene signature, built into a multiplexed-qPCR IVD prototype, showed an area under the curve of 0.97, a positive predictive value of 78%, and a negative predictive value of 98%. By Bayes' theorem, the IVD prototype is expected to achieve a positive predictive value of 64–82% and a negative predictive value of 97–99% in patients with a cancer prevalence range of 20–40%.Conclusions: A new multiplexed-qPCR IVD prototype is reported that accurately classifies thyroid nodules and may provide a future solution suitable for local reference laboratory testing.

Background: Convalescent plasma (CP), despite limited evidence on its efficacy, is being widely used as a compassionate therapy for hospitalized patients with COVID-19. We aimed to evaluate the efficacy and safety of early CP therapy in COVID-19 progression. Methods: Open-label, single-center, randomized clinical trial performed in an academic center in Santiago, Chile from May 10, 2020, to July 18, 2020, with final follow-up August 17, 2020. The trial included patients hospitalized within the first 7 days of COVID-19 symptoms onset, presenting risk factors for illness progression and not on mechanical ventilation. The intervention consisted in immediate CP (early plasma group) versus no CP unless developing pre-specified criteria of deterioration (deferred plasma group). Additional standard treatment was allowed in both arms. The primary outcome was a composite of mechanical ventilation, hospitalization for >14 days or death. Key secondary outcomes included: time to respiratory failure, days of mechanical ventilation, hospital length-of-stay, mortality at 30 days, and SARS-CoV-2 RT-PCR clearance rate. Results: Of 58 randomized patients (mean age, 65.8 years, 50% male), 57 (98.3%) completed the trial. A total of 13 (43.3%) participants from the deferred group received plasma based on clinical aggravation. We found no benefit in the primary outcome (32.1% vs 33.3%, OR 0.95, 95% CI 0.32-2.84, p>0.99) in the early versus deferred CP group. In-hospital mortality rate was 17.9% vs 6.7% (OR 3.04, 95% CI 0.54-17.2, p=0.25), mechanical ventilation 17.9% vs 6.7% (OR 3.04, 95% CI 0.54-17.2, p=0.25), and prolonged hospitalization 21.4% vs 30% (OR 0.64, 95%CI, 0.19-2.1, p=0.55) in early versus deferred CP group, respectively. Viral clearance rate on day 3 (26% vs 8%, p=0.20) and day 7 (38% vs 19%, p=0.37) did not differ between groups. Two patients experienced serious adverse events within 6 or less hours after plasma transfusion. Conclusion: Immediate addition of CP therapy in early stages of COVID-19 -compared to its use only in case of patient deterioration- did not confer benefits in mortality, length of hospitalization or mechanical ventilation requirement.

Background: Although most thyroid nodules with indeterminate cytology are benign, in most of the world, surgery remains as the most frequent diagnostic approach. We have previously reported a 10-gene thyroid genetic classifier, which accurately predicts benign thyroid nodules. The assay is a prototype diagnostic kit suitable for reference laboratory testing and could potentially avoid unnecessary diagnostic surgery in patients with indeterminate thyroid cytology. Methods: Classifier performance was tested in two independent, ethnically diverse, prospective multicenter trials (TGCT-1/Chile and TGCT-2/USA). A total of 4061 fine-needle aspirations were collected from 15 institutions, of which 897 (22%) were called indeterminate. The clinical site was blind to the classifier score and the clinical laboratory blind to the pathology report. A matched surgical pathology and valid classifier score was available for 270 samples. Results: Cohorts showed significant differences, including (i) clinical site patient source (academic, 43% and 97% for TGCT-1 and-2, respectively); (ii) ethnic diversity, with a greater proportion of the Hispanic population (40% vs. 3%) for TGCT-1 and a greater proportion of African American (11% vs. 0%) and Asian (10% vs. 1%) populations for TGCT-2; and (iii) tumor size (mean of 1.7 and 2.5 cm for TGCT-1 and-2, respectively).

The variant of concern (VOC) SARS-CoV-2 Omicron (B.1.1529) has been described as a highly contagious variant but less virulent than the current variant being monitored (VBM) Delta (B.1.617.2), causing fewer cases of hospitalizations, symptomatology, and deaths associated with COVID-19 disease. Although the epidemiological comparison of both variants has been previously reported in other countries, no report indicates their behavior and severity of infection in Chile. In this work, we report for the first time the effect of the Omicron and Delta variants in a cohort of 588 patients from the Hospital de Urgencia Asistencia pública (HUAP), a high-complexity health center in Santiago, Chile. This report is framed at the beginning of Chile's third wave of the COVID-19 pandemic, with a marked increase in the Omicron variant and a decrease in the circulating Delta variant. Our results indicated a similar proportion of patients with a complete vaccination schedule for both variants. However, the Delta variant was associated with a higher prevalence of hospitalization and more significant symptomatology associated with respiratory distress. On the other hand, our data suggest that vaccination is less effective in preventing infection by the Omicron variant. This antecedent, with a low severity but high contagiousness, suggests that the Omicron variant could even collapse the primary health care service due to the high demand for health care.

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e18500 Background: The interaction of acute myeloid leukemia (AML) with the bone marrow stroma (BMS) determines a protective microenvironment that favors leukemia development and resistance to chemotherapy. We developed an in vitro platform to study leukemia and stroma interaction, and showed that BMS secretes soluble factors protecting AML cells from Ara-C-induced apoptosis, which correlated with clinical patient outcomes. Methods: BMS from AML patients and healthy donors were cultured to perform chemo-sensitivity studies with Ara-C on THP-1 cells. A Resistance Factor was calculated (RF = IC50 stroma conditioned medium (CM)/IC50 control medium) to classify BMS as “protective” (PS: confers chemo-resistance) or “non-protective” (NPS: does not confer chemo-resistance). Characterization of myofibroblasts in BMS cultures was performed by WB. Quantification of cytokines from primary BMS CM was performed by Luminex. The differential expression of epithelial-mesenquimal-like (EMT-like) and stem cell-markers in THP-1 cells incubated with primary BMS CM was measured by qPCR. Results: We recruited 90 AML patients and 10 healthy BM donors. AML cohort showed 31 patients with PS and 59 patients with NPS. PS patients had a significant poor overall survival (OS) compared with NPS patients (44% versus 70% OS in 2.5 years, median survival 7.3 months versus 20.7 months, HR 2.36). The stroma from healthy BM donors did not confer resistance to THP-1 cells. BMS in both, PS and NPS have activated myofibroblasts and analysis of cytokine expression showed differential expression between groups. THP-1 cells incubated with PS showed significant expression of EMT- and stem cell-markers like Twist, Vimentin, CD44 and CD34 compared to THP-1 cells incubated with NPS and control medium. Conclusions: The capacity of the BMS from AML patients to modulate chemoresistance is a strong prognostic factor for OS, and PS patients have a worst OS compared with NPS patients. Stroma from healthy donors has a NPS phenotype. We propose that the leukemia is capable of educating the stroma to acquire secondarily the capacity to confer resistance to leukemia cells to favor tumor progression and chemoresistance.