New drug development is a time-consuming and expensive process. Recently, there has been stagnation in the development of novel compounds. Moreover, the attrition rate in clinical research is also on the rise. Fearing more stagnation, the Food and Drug Administration released the critical path initiative in 2004 and critical path opportunity list in 2006 thus highlighting the need of advancing innovative trial designs. One of the innovations suggested was the adaptive designed clinical trials, a method promoting introduction of pre-specified modifications in the design or statistical procedures of an on-going trial depending on the data generated from the concerned trial thus making a trial more flexible. The adaptive design trials are proposed to boost clinical research by cutting on the cost and time factor. Although the concept of adaptive designed clinical trials is round-the-corner for the last 40 years, there is still lack of uniformity and understanding on this issue. This review highlights important adaptive designed methodologies besides covering the regulatory positions on this issue.

Presentation to APEC Preliminary Workshop on Review of Drug Development in Clinical Trials.

Phase I clinical trials are an essential step in the development of anticancer drugs. The main goal of these studies is to establish the recommended dose and/or schedule of new drugs or drug combinations for phase II trials. The guiding principle for dose escalation in phase I trials is to avoid exposing too many patients to subtherapeutic doses while preserving safety and maintaining rapid accrual. Here we review dose escalation methods for phase I trials, including the rule-based and model-based dose escalation methods that have been developed to evaluate new anticancer agents. Toxicity has traditionally been the primary endpoint for phase I trials involving cytotoxic agents. However, with the emergence of molecularly targeted anticancer agents, potential alternative endpoints to delineate optimal biological activity, such as plasma drug concentration and target inhibition in tumor or surrogate tissues, have been proposed along with new trial designs. We also describe specific methods for drug combinations as well as methods that use a time-to-event endpoint or both toxicity and efficacy as endpoints. Finally, we present the advantages and drawbacks of the various dose escalation methods and discuss specific applications of the methods in developmental oncotherapeutics.

 In the United States, drugs and medical devices are regulated by the US Food and Drug Administration (FDA). A drug must undergo rigorous testing prior to marketing to and medical use by the general public. The FDA grants marketing approval for drug products based on a comprehensive review of safety and efficacy data. This review article explains the history behind the establishment of the FDA and examines the historical legislation and approval processes for drugs, specifically in the fields of medical oncology and hematology. The agents imatinib (Gleevec, Novartis) and decitabine (Dacogen, Eisai) are used to illustrate both the current FDA regulatory process—specifically the orphan drug designation and accelerated approval process—and why decitabine failed to gain an indication for acute myeloid leukemia. The purpose and construct of the Oncologic Drugs Advisory Committee are also discussed, along with examples of 2 renal cell cancer drugs—axitinib (Inlyta, Pfizer) and tivozanib—that used progression-free survival as an endpoint. Regulatory approval of oncology drugs is the cornerstone of the development of new treatment agents and modalities, which lead to improvements in the standard of cancer care. The future landscape of drug development and regulatory approval will be influenced by the new breakthrough therapy designation, and choice of drug will be guided by genomic insights. 

The mission of FDA's Center for Drug Evaluation and Research (CDER) is to ensure that drugs marketed in this country are safe and effective. CDER does not test drugs, although the Center's Office of Testing and Research does conduct limited research in the areas of drug quality, safety, and effectiveness.

This guidance represents the Food and Drug Administration’s (FDA’s) current thinking on this topic. It does not create or confer any rights for or on any person and does not operate to bind FDA or the public. You can use an alternative approach if the approach satisfies the requirements of the applicable statutes and regulations. If you want to discuss an alternative approach, contact the FDA staff responsible for implementing this guidance. If you cannot identify the appropriate FDA staff, call the appropriate number listed on the title page of this guidance. 

The process of getting a drug to market, from first testing to final FDA approval, is summarized in a figure and described at greater length.

New drugs are usually compared to a placebo. Sometimes it may be unethical to give patients a placebo, so the new drug is compared with standard treatment. Trials which compare treatments may not be designed to show that one treatment is superior. These are known as non-inferiority or equivalence trials. Non-inferiority trials aim to show that the new drug is no worse than standard treatment. Equivalence trials aim to show the new treatment is no better and no worse. An equivalence boundary should be set before the trial. This is the definition of what would be the minimum important difference between the treatments. There are several traps in the interpretation of trials of non-inferiority or equivalence. The results can be influenced by many factors including the size of the equivalence boundary and whether an intention-to-treat or ‘per protocol’ analysis is used.

Conventional phase 2 clinical trials are typically single-arm experiments, with outcome characterized by one binary “response” variable. Clinical investigators are poorly served by such conventional methodology. We contend that phase 2 trials are inherently comparative, with the results of the comparison determining whether to conduct a subsequent phase 3 trial. When different treatments are studied in separate single-arm trials, actual differences between response rates associated with the treatments, “treatment effects,” are confounded with differences between the trials, “trial effects.” Thus, it is impossible to estimate either effect separately. Consequently, when the results of separate single-arm trials of different treatments are compared, an apparent treatment difference may be due to a trial effect. Conversely, the apparent absence of a treatment effect may be due to an actual treatment effect being cancelled out by a trial effect. Because selection involves comparison, single-arm phase 2 trials thus fail to provide a reliable means for selecting which therapies to investigate in phase 3. Moreover, reducing complex clinical phenomena, including both adverse and desirable events, to a single outcome wastes important information. Consequently, conventional phase 2 designs are inefficient and unreliable. Given the limited number of patients available for phase 2 trials and the increasing number of new therapies that must be evaluated, it is critically important to conduct these trials efficiently. These concerns motivated the development of a general paradigm for randomized selection trials evaluating several therapies based on multiple outcomes. Three illustrative applications of trials using this approach are presented.

The FDA granted Gleevec a priority review and approved the drug after only a 2 ½-month review time, making this the fastest approval to market any cancer treatment.