Clin Cancer Res
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Clinical trials have commenced to evaluate the feasibility of targeting malignant gliomas with genetically engineered CTLs delivered directly to the tumor bed in the central nervous system. The objective of this study is to determine a suite of magnetic resonance imaging (MRI) measurements using an orthotopic xenograft murine model that can noninvasively monitor immunologically mediated tumor regression and reactive changes in the surrounding brain parenchyma. ⋯ The present study indicates the feasibility of MRI to visualize different phases of immune response when IL-13Ralpha2-specific CTLs are administered directly to the glioma tumor bed. This will further the aim of better predicting clinical outcome following immunotherapy.
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Although the concept of a phase 0 trial is a relatively new one, there has been a slowly increasing trend toward basing early clinical trial designs on pharmacokinetic and pharmacodynamic end points that has been developing over many years. This article will review the early cancer trial methodologies and the various techniques that have been used to refine them. ⋯ Four trial designs that are essentially developed for cytotoxic agents using the maximal tolerated dose as an end point are described. Although these trials were not designed with the use of more sophisticated pharmacodynamic end points (such as the measurement of the effect of a targeted agent on its target), they have been developed to optimize the speed with which a dose needed to achieve a particular effect can be determined and are, to this extent, relevant to the design of studies with pharmacodynamic end points.
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Recent guidance from the Food and Drug Administration supports the conduct of a new type of exploratory clinical trial, commonly called phase 0 clinical trials. Proponents argue that phase 0 clinical trials have the potential to expedite the development of new oncology drugs while exposing fewer research subjects to the risks of experimental treatments. ⋯ Further concern focuses on the inclusion of terminally ill and consequently vulnerable cancer patients in these trials. To evaluate these concerns, this article considers relevant empirical data from phase 1 oncology trials and develops several recommendations regarding the conduct of phase 0 clinical trials in oncology.
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In 2006, the U. S. Food and Drug Administration published its guide on exploratory investigational new drug (IND) studies with the goal of making the approach to early-stage, pilot clinical trials more flexible within the context of current regulations. ⋯ These studies may be important vehicles for the conduct of proof-of-principle pharmacodynamic investigations of highly potent molecules, for bioavailability studies that require only a single drug dose to be administered, and for imaging trials that permit critical dosimetry and biodistribution investigations of new molecules. These trials were done with no therapeutic intent and must be followed by traditional dose-escalation investigations that are supported by standard preclinical toxicologic and pharmacologic studies. To the extent that they allow early evaluations of essential drug characteristics that can only be obtained in humans, exploratory IND trials have the potential to limit the cost and improve the development times of new agents.