Scientific and regulatory reasons for delay and denial of FDA approval of initial applications for new drugs, 2000-2012.

IMPORTANCE: Some new drug applications fail because of inadequate drug performance and others are not approved because the information submitted to the US Food and Drug Administration (FDA) is unsatisfactory to make that determination. Resubmission of failed applications is costly, delaying marketing approval and the availability of new drugs to patients. OBJECTIVE: To identify the reasons that FDA marketing approval for new drugs was delayed or denied. DESIGN, SETTING, AND PARTICIPANTS: A retrospective review of FDA documents and extraction of data were performed. We examined all drug applications first submitted to the FDA between 2000 and 2012 for new molecular entities (NMEs), which are active ingredients never before marketed in the United States in any form. Using FDA correspondence and reviews, we investigated the reasons NMEs failed to obtain FDA approval. MAIN OUTCOMES AND MEASURES: Reasons for delayed FDA approval or nonapproval of NME applications. RESULTS: Of the 302 identified NME applications, 151 (50%) were approved when first submitted and 222 (73.5%) were ultimately approved. Seventy-one applications required 1 or more resubmissions before approval, with a median delay to approval of 435 days following the first unsuccessful submission. Of the unsuccessful first-time applications, 24 (15.9%) included uncertainties related to dose selection, 20 (13.2%) choice of study end points that failed to adequately reflect a clinically meaningful effect, 20 (13.2%) inconsistent results when different end points were tested, 17 (11.3%) inconsistent results when different trials or study sites were compared, and 20 (13.2%) poor efficacy when compared with the standard of care. The frequency of safety deficiencies was similar among never-approved drugs compared with those with delayed approval (43 of 80 never approved [53.8%] vs 37 of 71 eventually approved [52.1%]; difference, 1.7% [95% CI, -14.86% to 18.05%]; P = .87). However, efficacy deficiencies were significantly more frequent among the never-approved drugs than among those with delayed approvals (61 of 80 never approved [76.3%] vs 28 of 71 eventually approved [39.4%]; difference, 36.9% [95% CI, 20.25% to 50.86%]; P < .001). CONCLUSIONS AND RELEVANCE: Several potentially preventable deficiencies, including failure to select optimal drug doses and suitable study end points, accounted for significant delays in the approval of new drugs. Understanding the reasons for previous failures is helpful to improve the efficiency of clinical development for new drugs.

Evaluation of a Sequential Antibiotic Treatment Regimen of Ampicillin, Ciprofloxacin and Fosfomycin against Escherichia coli CFT073 in the Hollow Fiber Infection Model Compared with Simultaneous Combination Treatment.

OBJECTIVE: Employ the hollow fiber infection model (HFIM) to study sequential antibiotic administration (ampicillin, ciprofloxacin and fosfomycin) using human pharmacokinetic profiles to measure changes in the rate of antibiotic resistance development and compare this to simultaneous combination therapy with the same antibiotic combinations. METHODS: Escherichia coli CFT073, a clinical uropathogenic strain, was exposed individually to clinically relevant pharmacokinetic concentrations of ampicillin on day 1, ciprofloxacin on day 2 and fosfomycin on day 3. This sequence was continued for 10 days in the HFIM. Bacterial samples were collected at different time points to enumerate total and resistant bacterial populations. The results were compared with the simultaneous combination therapy previously studied. RESULTS: Sequential antibiotic treatment (ampicillin-ciprofloxacin-fosfomycin sequence) resulted in the early emergence of single and multi-antibiotic-resistant subpopulations, while the simultaneous treatment regimen significantly delayed or prevented the emergence of resistant subpopulations. CONCLUSION: Sequential administration of these antibiotic monotherapies did not significantly delay the emergence of resistant subpopulations compared to simultaneous treatment with combinations of the same antibiotics. Further studies are warranted to evaluate different sequences of the same antibiotics in delaying emergent resistance.

Challenges, successes and hopes in the development of novel TB therapeutics.

Despite efficacious drugs for treatment, TB continues to affect enormous numbers of patients throughout the world. Failure to control TB may be related to the biological characteristics of Mycobacterium tuberculosis, the nature of susceptible hosts often impoverished and poorly supported by healthcare infrastructure and the complex treatment regimens that must be used. Challenges to anti-TB drug development include the organism's slow replication, the ability of M. tuberculosis to survive in a dormant state and to persist despite therapy, its impregnable cell wall and its capacity to develop resistance to drugs. The need for extended therapy using combinations of drugs remains a practical obstacle to effective control in poor, malnourished and diseased communities most susceptible to TB. High-throughput screening of candidate agents and investigation of drugs already in use for other infections are yielding promising new candidates for TB treatment. New families of drugs entering clinical trials include 5-nitroimidazoles, diarylquinolines and ethylene diamines. Increasing funding initiatives, advances in the biology of TB and strategies for drug discovery have rejuvenated the pipeline of new drugs for TB, promising an expanding armamentarium of effective drugs with improved tolerability and potential to treat drug-resistant cases.

Developing new drugs for the treatment of drug-resistant tuberculosis: a regulatory perspective.

Simplifying and shortening treatment for drug-sensitive tuberculosis and providing new treatment options for drug-resistant tuberculosis constitute two principal goals in the development of novel drugs for tuberculosis. Demonstration of clinical efficacy in drug-sensitive tuberculosis is challenging, given high success rates for existing regimens, concerns about substituting an investigational agent for the most effective agents in a regimen and difficulties in determining the effect size of the components of a combination regimen. Large and prolonged studies would be needed either to show superiority over existing regimens or statistically defensible non-inferiority compared to existing regimens. In contrast, exploring efficacy of novel treatments in the setting of drug-resistant disease may present certain opportunities. In drug-resistant disease, the efficacy of existing regimens is comparatively poor, and companion drugs used to treat drug-resistant disease are weak or ineffective, enabling demonstration of the effect of the new drug. Other advantages of this approach, which has been used successfully in the development of antiretroviral agents, include the possibility of demonstrating drug efficacy using smaller studies, the possibility of accelerated approval based on a surrogate endpoint and the opportunity to address an urgent public health need. Experience with the activity and the safety of new agents in drug-resistant disease may provide a platform from which their indication can be broadened to include drug-sensitive disease.