Application of restricted mean survival time in clinical follow-up study / 中华流行病学杂志

In clinical follow-up studies, hazard ratio (HR) is routinely used to quantify the differences between-groups, however, it is being estimated by the Cox procedure. HR, the ratio of two hazard functions has abstract meaning only and is in lack of the context to give an intuitive explanation of the survival of patients and the assumption of proportional hazards (PH) must be satisfied. Under this context, the restricted mean survival time (RMST) can be used as a relatively effective measure or index of statistics. This paper introduces the RMST-based statistical analysis methods, including estimation of RMST and its difference, hypothesis testing and regression analysis. The application of RMST in data analysis is also introduced. All the evidence demonstrates that RMST can be used as an effective analytical tool with straightforward interpretation. RMST is also more effective than HR in comparing differences between groups, when non-PH is observed. Therefore, RMST is suggested to be stated along with HR in the process of disease efficacy evaluation and prognosis analysis. Cooperation and complement of the two, a precise reflection on the characteristics of data can be expected.

Endpoints in advanced breast cancer: methodological aspects & clinical implications.

Breast cancer is an increasingly important public health problem in developing countries, with disproportionately high mortality. The increasing availability of active agents against advanced breast cancer makes the development of novel treatments and their choice in clinical practice progressively more complex. Furthermore, there is often a tension between the adequacy of endpoints used in clinical trials and the clinician's aim of improving survival and quality of life, the two most important therapeutic goals in advanced breast cancer. However, overall survival (OS) is no longer a suitable indicator of treatment efficacy within clinical trials in settings for which effective subsequent-line therapy exists. Conversely, progression-free survival (PFS) currently represents the most sensitive parameter to assess the efficacy of a new drug or combination in such settings. When coupled with a favourable toxicity profile and cost, the demonstration of an improved PFS may be enough evidence for the superiority of a treatment. Despite arguments favouring the use of PFS as a primary endpoint in clinical trials, clinicians who need to make sense of the available literature may be reluctant to use PFS as an indicator of clinical benefit when deciding among different therapeutic strategies for their patients. This choice is further complicated if one fails to distinguish between the use of an efficacy parameter as an indicator of therapeutic objective for individual patients and as a clinical trial endpoint. This brief review aims at helping clinicians in their daily need to interpret the literature and make informed treatment choices for patients with advanced breast cancer.

Reactivity of p53 protein in canine transmissible venereal tumor / Reatividade da proteína P53 no tumor venéreo transmissível canino

The expression of p53 protein was evaluated in canine transmissible venereal tumor (CTVT), as following: natural occurrence (n=8); resistant to chemotherapy (n=4); and allogeneic transplanted in progression (n=8), stable (n=8), and regression (n=8)stages. The collected specimens were submitted to GM1 immunohistochemical reaction. Results showed a mean percentage of immunomarked cells around 18.6 percent in CTVT of natural occurrence, 23.8 percent in CTVT resistant to chemotherapy, 22.9 percent in allogeneic transplanted CTVT in both progression and stable stages, and 35.8 percent in transplanted CTVT in regression stage. The results suggest that there is a functional abnormality in p53 gene and its products in the studied tumors; although, it is not possible to correlate the percentage of cells marked by p53 and a prognosis.

A expressão da proteína p53 foi avaliada em espécimes de tumor venéreo transmissível canino (TVT) de ocorrência natural (n=8); resistente à quimioterapia (n=4) e transplantado em cão nas fases de progressão tumoral (n=8), de latência (n=8) e de regressão (n=8). Os espécimes foram submetidos à reação de imunoistoquímica. Os resultados mostraram porcentagem média de células imunomarcadas de 18,6 por cento no TVT de ocorrência natural, de 23,8 por cento no TVT refratário, 22,9 por cento nos TVTs transplantados nas fases de progressão e latência e de 35,8 por cento na fase de regressão. Os resultados sugerem que há uma anormalidade funcional no gene P53 e seus produtos nos tumores estudados, apesar de não ser possível correlacionar a porcentagem de células marcadas pelo p53 ao prognóstico.

Application of HIV-1-green fluorescent protein (GFP) reporter viruses in neutralizing antibody assays.

We made reporter HIV-1 DNA constructs carrying green fluorescent protein (GFP) gene and exchangeable env of subtype E. The recombinant constructs were used to produce infectious reporter viruses, which induced infected cells to emit green fluorescent light and rendered them easily detectable at single cell level. Because the env in this construct can be easily exchanged, viruses with different antigenic epitopes can be made. We used these reporter viruses to set up a neutralizing antibody assay based on fluorescence reduction by flow cytometric measurement. The result of this new assay correlated with the standard infectivity reduction assay using primary isolates. Because this new assay is faster and much less costly than the standard assay using a p24 endpoint and can be performed in peripheral blood mononuclear cells (PBMC), it provides a useful tool for analysis of HIV-1 immune responses.