Trial endpoints for drug approval in oncology: Chemoprevention

Agonist replacement for stimulant dependence: a review of clinical research

Stimulant use disorders are an unrelenting public health concern worldwide. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. The present paper reviewed clinical data from human laboratory self-administration studies and clinical trials to determine whether agonist replacement therapy is a viable strategy for managing cocaine and/or amphetamine use disorders. The extant literature suggests that agonist replacement therapy may be effective for managing stimulant use disorders, however, the clinical selection of an agonist replacement medication likely needs to be based on the pharmacological mechanism of the medication and the stimulant abused by patients. Specifically, dopamine releasers appear most effective for reducing cocaine use whereas dopamine reuptake inhibitors appear most effective for reducing amphetamine use.

Combination pharmacotherapies for stimulant use disorder: a review of clinical findings and recommendations for future research

Despite concerted efforts to identify a pharmacotherapy for managing stimulant use disorders, no widely effective medications have been approved. Innovative strategies are necessary to develop successful pharmacotherapies for stimulant use disorders. This manuscript reviews human laboratory studies and clinical trials to determine whether one such strategy, use of combination pharmacotherapies, holds promise. The extant literature shows that combination pharmacotherapy produced results that were better than placebo treatment, especially with medications shown to have efficacy as monotherapies. However, many studies did not compare individual constituents to the combination treatment, making it impossible to determine whether combination treatment is more effective than monotherapy. Future research should systematically compare combined treatments with individual agents using medications showing some efficacy when tested alone.

Evolving strategies for prostate cancer chemoprevention trials

Prostate cancer chemoprevention (CP) can be defined as the use of natural and synthetic agents that inhibit, reverse or regress precancer and delay progression to invasive cancer. During the past two decades several CP strategies have evolved. The first generation of CP trials tested the efficacy of antioxidants and vitamins including B-carotene, vitamin A, retinol, 13 cis retinoic acid, vitamins E, C and selenium. Although these trials were disappointing, provocative hypotheses were generated for selenium and vitamin E that set the stage for future prostate trials. In the 1990s, the NCI launched a second generation of large CP trials aimed at breast and prostate cancer. One of these trials is the PCPT, testing the efficacy of a 5 alpha-reductase inhibitor-finasteride to prevent prostate cancer in 18,000 men. Although PCPT is still in progress, the NCI recently launched a second large primary prostate CP trial called SELECT, testing the efficacy of selenium and vitamin E in 32,400 men. The Prostate Cancer Progress Report to the Director of NCI in 1998 challenged the research community to design more efficient CP trials for prostate cancer. In response, the NCI has evolved a third generation of CP trials. This involves pharmacologically driven translational science research including agents and their targets, biomarker endpoints, suitable clinical models for testing agents and efficient trial designs employing high risk cohorts and surrogate endpoints. In summary, a dual strategy for CP is being developed which includes public health measures and a medical intervention approach.