Genotyping cell-free tumor DNA in the blood to detect residual disease and drug resistance.

DNA fragments released from cancer cells into the blood can be used to generate molecular profiles of tumors. Non-invasive 'liquid biopsies' can be used to monitor minimal residual disease and detect the emergence of drug resistance

Failure is not final: ctDNA-guided rechallenge therapy in colorectal cancer.

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Combinación de Proyecciones para el Precio del Petróleo: Aplicación y Evaluación de Metodologías

This paper conducts an exhaustive out-of-sample forecasting evaluation exercise for the monthly price of crude oil between 1992 and 2011. The idea is to identify the forecasting strategy that results in the “best” forecasts in terms of mean forecasting error. To this end, a wide variety of econometric models as well as future prices are tested for different forecasting horizons in an individual manner, as well as combined. We find that for short horizons (1 and 3 months), an ARIMA specification results in smaller forecasting errors, but for longer horizons (6-24 months), future prices outperform other models. All models are found to underestimate the true price of oil, on average. The combination of these individual models only yields smaller forecasting errors when compared to the “best” individual strategy in a restricted sample ending in 2005. Nevertheless, when we tabulate the number of times one strategy yields the largest forecasting error compared to other alternatives, combinations of forecasts never yields the highest absolute error except one month ahead. These results are robust to the sample selection.

Efectos de la Exención Tributaria a las Ganancias de Capital en el Precio de las Acciones en Chile

La Reforma al Mercado de Capitales de 2001 en Chile (MK I), estableció la exención del impuesto a la renta para las ganancias de capital provenientes de la enajenación de acciones con presencia bursátil mayor al 25%. Los objetivos de la reforma eran aumentar la participación, la profundidad y la liquidez en el mercado local de acciones. Sin embargo, no es evidente cuál es el efecto que tiene una rebaja tributaria en el precio de las acciones ya que hay dos efectos que actúan en sentido contrario. Por un lado, hay un efecto de capitalización que lleva a un aumento en los precios. Por otro lado, hay un efecto lock-in que lleva a una reducción en los precios. Determinar cuál efecto domina es, por lo tanto, una pregunta que debe responderse empíricamente. Este trabajo contribuye a responder esa pregunta, determinando empíricamente los efectos que tuvo la exención tributaria introducida en 2001 en el precio de las acciones en Chile. Utilizando un estimador de diferencias en diferencias, los resultados muestran un impacto anticipado promedio de alrededor de -14% en el precio de las acciones que se cotizan en la Bolsa de Santiago frente a la futura exención tributaria. La elasticidad del precio respecto a la tasa de impuesto, entre 0.006 y 0.01, es mucho menor a la estimada en la literatura económica para otros países a partir de reformas similares, donde la elasticidad fluctúa entre 0.20 y 0.27. Sin embargo, es de magnitud similar a la elasticidad estimada para períodos de tiempo donde el efecto lock-in domina.Ganancias de Capital, Incidencia Tributaria, Mercado de Capitales, Precio de Acciones.

How liquid biopsies can change clinical practice in oncology

Abstract Cell-free DNA fragments are shed into the bloodstream by tumor cells. The analysis of circulating tumor DNA (ctDNA), commonly known as liquid biopsy, can be exploited for a variety of clinical applications. ctDNA is being used to genotype solid cancers non-invasively, to track tumor dynamics and to detect the emergence of drug resistance. In a few settings, liquid biopsies have already entered clinical practice. For example, ctDNA is used to guide treatment in a subset of lung cancers. In this review, we discuss how recent improvements in the sensitivity and accuracy of ctDNA analyses have led to unprecedented advances in this research field. We further consider what is required for the routine deployment of liquid biopsies in the clinical diagnostic space. We pinpoint technical hurdles that liquid biopsies have yet to overcome, including preanalytical and analytical challenges. We foresee how liquid biopsies will transform clinical practice: by complementing (or replacing) imaging to monitor treatment response and by detecting minimal residual disease after surgery with curative intent