Esomeprazole FDA Approval in Children With GERD: Exposure-Matching and Exposure-Response.

OBJECTIVES: Food and Drug Administration approval of proton-pump inhibitors for infantile gastroesophageal reflux disease has been limited by intrapatient variability in the clinical assessment of gastroesophageal reflux disease. For children 1 to 17 years old, extrapolating efficacy from adults for IV esomeprazole was accepted. The oral formulation was previously approved in children. Exposure-response and exposure matching analyses were sought to identify approvable pediatric doses. METHODS: Intragastric pH biomarker comparisons between children and adults were conducted. Pediatric doses were selected to match exposures in adults and were based on population pharmacokinetic (PK) modeling and simulations with pediatric esomeprazole data. Observed IV or oral esomeprazole PK data were available from 50 and 117 children, between birth and 17 years, respectively, and from 65 adults, between 20 and 48 years. A population PK model developed using these data was used to simulate steady-state esomeprazole exposures for children at different doses to match the observed exposures in adults. RESULTS: Exposure-response relationships of intragastric pH measures were similar between children and adults. The PK simulations identified a dosing regimen for children that results in comparable steady-state area under the curve to that observed after 20 mg in adults. For IV esomeprazole, increasing the infusion duration to 10 to 30 minutes in children achieves matching Cmax values with adults. CONCLUSIONS: The exposure-matching analysis permitted approval of an esomeprazole regimen not studied directly in clinical trials. Exposure-response for intragastric pH-permitted approval for the treatment of gastroesophageal reflux disease in children in whom it was not possible to evaluate the adult primary endpoint, mucosal healing assessed by endoscopy.

Immune response to enzyme replacement therapies in lysosomal storage diseases and the role of immune tolerance induction.

The US Food and Drug Administration (FDA) and National Organization for Rare Disease (NORD) convened a public workshop titled "Immune Responses to Enzyme Replacement Therapies: Role of Immune Tolerance Induction" to discuss the impact of anti-drug antibodies (ADAs) on efficacy and safety of enzyme replacement therapies (ERTs) intended to treat patients with lysosomal storage diseases (LSDs). Participants in the workshop included FDA staff, clinicians, scientists, patients, industry, and advocacy group representatives. The risks and benefits of implementing prophylactic immune tolerance induction (ITI) to reduce the potential clinical impact of antibody development were considered. Complications due to immune responses to ERT are being recognized with increasing experience and lengths of exposure to ERTs to treat several LSDs. Strategies to mitigate immune responses and to optimize therapies are needed. Discussions during the workshop resulted in the identification of knowledge gaps and future areas of research, as well as the following proposals from the participants: (1) systematic collection of longitudinal data on immunogenicity to better understand the impact of ADAs on long-term clinical outcomes; (2) development of disease-specific biomarkers and outcome measures to assess the effect of ADAs and ITI on efficacy and safety; (3) development of consistent approaches to ADA assays to allow comparisons of immunogenicity data across different products and disease groups, and to expedite reporting of results; (4) establishment of a system to widely share data on antibody titers following treatment with ERTs; (5) identification of components of the protein that are immunogenic so that triggers and components of the immune responses can be targeted in ITI; and (6) consideration of early ITI in patients who are at risk of developing clinically relevant ADA that have been demonstrated to worsen treatment outcomes.

Exposure-Response of Palonosetron for Prevention of Chemotherapy-Induced Nausea and Vomiting in Pediatric Patients.

OBJECTIVES: Extrapolation of efficacy from adult populations to pediatrics may be appropriate if it is reasonable to assume that the 2 populations have similar disease progression and response to intervention. When full extrapolation of efficacy is deemed appropriate, the pediatric dose can be determined by "matching" exposure to a drug with that observed in adult patients. This approach has been used in certain therapeutic areas to alleviate the burden of pediatric clinical trials. We present here a case in which exposure matching is not appropriate. METHODS: Data analyses including pharmacokinetics and exposure-response were performed using data obtained from 2 pediatric chemotherapy-induced nausea and vomiting trials for intravenously administered palonosetron (Aloxi; a 5-HT3 receptor antagonist) injection and the results were compared with adult findings. RESULTS: At the approved doses for adults (0.25 mg) and pediatric patients (20 µg/kg), mean systemic exposure (area under the curve) of palonosetron in pediatric patients was approximately 3-fold higher than that in adults, whereas the response rate was similar between the 2 populations. Across pediatric patients, those younger than 6 years of age appeared to have a higher response than those ages 6 years or older, even though estimated systemic exposure was comparable between these age groups. CONCLUSIONS: Overall, these analyses provide an example in which pediatric and adult exposure data alone are insufficient to adequately identify effective pediatric doses and raise questions about the appropriateness of exposure matching for other drugs in the same therapeutic class. In such cases, pediatric dose-ranging and efficacy studies are needed.

Well-defined and reliable clinical outcome assessments for pediatric Crohn disease: a critical need for drug development.

OBJECTIVES: The aim of the present study was to identify areas for further development of clinical outcome assessment (COA) in pediatric Crohn disease (CD). METHODS: The study analyzed the measurement properties of all existing COA tools for pediatric CD in literature and published registration trials of approved drugs for pediatric CD based on criteria described in Food and Drug Administration guidance for patient-reported outcome (PRO) development. RESULTS: The Pediatric Crohn's Disease Activity Index (PCDAI) and its derivatives (abbreviated, short, modified, and weighted PCDAIs) were reviewed. The Crohn's Disease Activity Index (CDAI) and Harvey-Bradshaw index (HBI), designed for adult patients, have been adapted for use in a few pediatric CD studies. The use of PCDAI as an endpoint in Remicade and Humira trials led to the Food and Drug Administration-approved indication in pediatric CD. Common issues in measurement properties of COA tools included the absence of direct patient or caregivers' input to generate the items measuring signs and symptoms; absence of evidence demonstrating correlation with clinically relevant inflammation observed with endoscopic measures; lack of standardization in measurement, age-appropriate interviewer script, and response rating criteria for the physician interviewer. CONCLUSIONS: Available evidence indicates that CDAI, HBI, and 5 versions of the PCDAI lack adequate measurement properties for use as a primary endpoint for phase 3 trials intended to support approval of products intended to treat pediatric CD. In order to facilitate pediatric drug development, a well-defined, reliable, sensitive, and globally recognized PRO that measures signs and symptoms in children with CD and that can be used in conjunction with endoscopy-based endpoints and/or biomarkers is sorely needed.

Steps toward harmonization for clinical development of medicines in pediatric ulcerative colitis-a global scientific discussion, part 1: efficacy endpoints and disease outcome assessments.

OBJECTIVES: There is a pressing need for drug development in pediatric ulcerative colitis (UC). Lack of scientific consensus on efficacy endpoints and disease outcome assessments presents a hurdle for global drug development in pediatric UC. Scientists from 4 regulatory agencies convened an International Inflammatory Bowel Disease Working Group (i-IBD Working Group) to harmonize present thinking about various aspects of drug development in pediatric UC globally. METHODS: The i-IBD Working Group was convened in 2012 by scientists from the US Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan. The members of this group considered reasons for differences in their acceptance of efficacy endpoints and disease activity indices used in pediatric UC, reviewed the available literature, and developed consensus opinions regarding approaches for evaluating outcomes in pediatric UC trials. RESULTS: There is lack of harmonization in using efficacy endpoint and outcome assessments including disease activity indices to assess clinical benefit in pediatric UC trials. Many disease activity indices have been developed, but their biometric properties, such as responsiveness, reliability, and validity, have not been properly validated. Biomarkers, such as fecal calprotectin and lactoferrin, are being investigated for their potential as noninvasive surrogate endpoints in UC. CONCLUSIONS: Consensus on the efficacy endpoints, disease activity indices, and outcome assessments is needed for globalization of pediatric UC trials. The i-IBD Working Group offers several perspectives to facilitate harmonization across regions. The development of noninvasive biomarkers as reliable surrogate endpoints needs to be explored further.

Steps toward harmonization for clinical development of medicines in pediatric ulcerative colitis-a global scientific discussion, part 2: data extrapolation, trial design, and pharmacokinetics.

OBJECTIVES: To facilitate global drug development, the International Pediatric Inflammatory Bowel Disease Working Group (i-IBD Working Group) discussed data extrapolation, trial design, and pharmacokinetic (PK) considerations for drugs intended to treat pediatric ulcerative colitis (UC), and considered possible approaches toward harmonized drug development. METHODS: Representatives from the US Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan convened monthly to explore existing regulatory approaches, reviewed the results of a literature search, and provided perspectives on pediatric UC drug development based on the available medical literature. RESULTS: Although pediatric UC, when compared with UC in adults, has a similar disease progression and response to intervention, the similarity of the exposure-response relation has not been adequately established. Consequently, clinical endpoints should be selected to optimally assess efficacy in children. The inclusion of a placebo control in pediatric trials to assure assay sensitivity may be appropriate under limited circumstances. In clinical studies, although the drug under investigation could provide possible direct benefit, placebo treatment should present no more than a minor increase over minimal risk to children with UC. CONCLUSIONS: Partial extrapolation of efficacy from informative adult studies may be appropriate. Placebo-controlled efficacy trials are scientifically and ethically appropriate for pediatric UC given appropriate patient selection and the use of early escape. Clinical studies in pediatric UC may include initial dose-finding studies and exposure-response modeling followed by an efficacy and safety study to further explore the exposure-response relation.

Proton pump inhibitor use in infants: FDA reviewer experience.

The Food and Drug Administration has completed its review of 4 clinical trials evaluating the use of proton pump inhibitors (PPIs) in infants (ages 1 month to <12 months) for the treatment of gastroesophageal reflux disease (GERD). An Advisory Committee meeting was held in November 2010 to discuss the potential reasons why PPI use in these trials failed to show a benefit in infants with GERD, and directions for future study. The present review summarizes the findings from the clinical trials. Potential mechanisms for the failed clinical trials are discussed. The safety of long-term use is also discussed. As a result of our analysis and review, the authors agree with the Advisory Committee members that PPIs should not be administered to treat the symptoms of GERD in the otherwise healthy infant without the evidence of acid-induced disease.

Evolution of clinical trials for irritable bowel syndrome: issues in end points and study design.

Irritable bowel syndrome (IBS) involves a broad range of physiological and psychological alterations that may affect brain-gut dysregulation, gut function, visceral perception, and mucosal integrity and function. Despite advances in our understanding of basic neuroenteric mechanisms and the role of effectors and transmitters in the brain-gut axis, a reliable biologic marker of IBS has yet to be identified. IBS diagnosis and status depend entirely on an assessment of IBS signs and symptoms. This has made development of optimal end points and study design for evaluation of efficacy of IBS drugs a challenge. This article addresses three main topics: the evolution of primary end points for IBS clinical trials; a potential path forward for IBS end points in new clinical trials; and recommendations for the future development of patient-reported outcome (PRO) instruments for use in IBS clinical trials.

Extrapolation of Adult Efficacy to Pediatric Patients With Chemotherapy-Induced Nausea and Vomiting.

Chemotherapy-induced nausea and vomiting (CINV) is a common treatment-related adverse event that negatively impacts the quality of life of cancer patients. During pediatric drug development, extrapolation of efficacy from adult to pediatric populations is a pathway that can minimize the exposure of children to unnecessary clinical trials, improve efficiency, and increase the likelihood of success in obtaining a pediatric indication. The acceptability of the use of extrapolation depends on a series of evidence-based assumptions regarding the similarity of disease, response to intervention, and exposure-response relationships between adult and pediatric patients. This study evaluated publicly available summaries of data submitted to the US Food and Drug Administration for drugs approved for CINV to assess the feasibility of extrapolation for future development programs. Extracted data included trial design, emetogenic potential of chemotherapy, primary end points, participant enrollment criteria, and antiemetic pharmacokinetics. Adult and pediatric clinical trial designs for assessment of efficacy and safety shared key design elements. Antiemetic drugs found to be efficacious in adults were also efficacious in pediatric patients. Systemic drug concentrations at approved doses were similar for ondansetron, granisetron, and aprepitant, but an exposure-response analysis of palonosetron in children suggested that higher palonosetron systemic exposure is necessary for the prevention of CINV in the pediatric population. For 5-hydroxytryptamine-3 and neurokinin-1 receptor antagonist antiemetic drugs, efficacy in adults predicts efficacy in children, supporting the extrapolation of effectiveness of an antiemetic product in children from adequate and well-controlled studies in adult patients with CINV.

Population pharmacokinetic-based dosing of intravenous busulfan in pediatric patients.

The objective of this study was to characterize the pharmacokinetics (PK) of intravenous busulfan in pediatric patients and provide dosing recommendations. Twenty-four pediatric patients were treated with intravenous busulfan, 1.0 or 0.8 mg/kg for ages < or = 4 years or > 4 years, respectively, 4 times a day for 4 days. Dense PK sampling was performed. Body weight, age, gender, and body surface area were explored for effects on PK, and Monte Carlo simulations were performed to assess different dosing regimens. The PK of intravenous busulfan was described by a 1-compartment model with clearance of 4.04 L/h/20 kg and volume of distribution of 12.8 L/20 kg. Simulations indicated that the mg/kg and mg/m2 regimens were similar and achieved the desired target exposure in approximately 60% of patients. This model suggests that patients < or = 12 kg should be dosed at 1.1 mg/kg and those > 12 kg dosed at 0.8 mg/kg. Therapeutic drug monitoring and dose adjustment will further improve therapeutic targeting.

Approval summary: imatinib mesylate in the treatment of metastatic and/or unresectable malignant gastrointestinal stromal tumors.

PURPOSE: Imatinib mesylate (Gleevec; Novartis, East Hanover, NJ)is a receptor tyrosine kinase inhibitor approved previously in 2001 by the United States Food and Drug Administration for the treatment of chronic myelogenous leukemia in blast crisis, accelerated phase, or in chronic phase after failure of IFN-alpha therapy. We review herein the clinical profile of this drug and the regulatory review leading to the approval of a supplemental New Drug Application for the treatment of metastatic and/or unresectable malignant gastrointestinal stromal tumors (GISTs). EXPERIMENTAL DESIGN: We discuss the efficacy and side effects of imatinib mesylate in a Phase II trial of 147 patients with metastatic and/or unresectable malignant GISTs, the basis for marketing approval, and postmarketing commitments by the drug's manufacturer. RESULTS: Imatinib was assessed in a single, open-label trial involving one European center and three centers in the United States. Seventy-three patients were randomly allocated to receive 400 mg of imatinib daily, and 74 patients received 600 mg daily. At the study report cutoff date, an objective response was confirmed in 56 patients; the overall response rate for the combined study arms was 38% (95% confidence interval, 30-46%). These responses were all partial responses. There was no statistically significant difference in response rates between the two dose groups. Adverse events included edema, fluid retention, nausea, vomiting, diarrhea, myalgias, skin rash, bone marrow suppression, bleeding, and elevations in aspartate aminotransferase, alanine aminotransferase, or bilirubin. Bleeding into the gastrointestinal tract or intratumoral sites occurred in 7 patients (5%) and was not correlated with thrombocytopenia or tumor bulk. The pharmacokinetics of imatinib in GIST patients were similar to those of chronic myelogenous leukemia patients. CONCLUSIONS: On February 1, 2001, imatinib mesylate was approved by the United States Food and Drug Administration for the treatment of malignant metastatic and/or unresectable GISTs. The recommended dose is 400 or 600 mg daily.

Proceedings From FDA/A.S.P.E.N. Public Workshop: Clinical Trial Design for Intravenous Fat Emulsion Products, October 29, 2013.

The development of intravenous fat emulsion (IVFE) is the culmination of physiological, biochemical, nutritional, and medical scientific advancements. IVFEs have the ability to deliver critical nutritional substrates to the patient. Recent literature purports that they may also play roles in modulation of immune functionality and pulmonary physiology, but data supporting these potential benefits are limited. While soybean-based IVFEs have comprised the dominant fat in U.S. markets, a number of other novel IVFEs may prove to optimize the care of children and adults in both hospitalized and home settings. The October 2013 U.S. Food and Drug Administration (FDA)/American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) Public Workshop brought together scientists, researchers, and clinical experts to present updated clinical perspectives of IVFEs, including historical development, current state of usage throughout the world, and considerations for the regulatory approval of new IVFEs in the United States.

Workshop on imaging science development for cancer prevention and preemption.

The concept of intraepithelial neoplasm (IEN) as a near-obligate precursor of cancers has generated opportunities to examine drug or device intervention strategies that may reverse or retard the sometimes lengthy process of carcinogenesis. Chemopreventive agents with high therapeutic indices, well-monitored for efficacy and safety, are greatly needed, as is development of less invasive or minimally disruptive visualization and assessment methods to safely screen nominally healthy but at-risk patients, often for extended periods of time and at repeated intervals. Imaging devices, alone or in combination with anticancer drugs, may also provide novel interventions to treat or prevent precancer.

Evaluation of health-related quality-of-life measures in oncology drug product applications: issues and concerns.

Health-related quality-of-life outcomes as reported by patients are valuable data and ideally should be critical to evaluating clinical benefit. The unblinded or open-label designs commonly adapted in oncology trials have the potential to introduce selection bias, reporting bias, and analyses bias. In this paper, issues surrounding use of patient reported outcomes to evaluate oncology drug products, including definition of hypothesis, study design, analysis, and interpretation of patient reported outcome data, are reported.

FDA drug approval summaries: oxaliplatin.

The purpose of this report is to summarize information on oxaliplatin, a drug recently approved by the U.S. Food and Drug Administration. Information provided includes regulatory history, study design, efficacy and safety results, and pertinent literature references. A single, multicenter, randomized trial, enrolling 463 patients with metastatic colorectal carcinoma whose disease had recurred or progressed during or within 6 months of completion of therapy with the combination of bolus 5-fluorouracil (FU)/leucovorin (LV) and irinotecan, was submitted. Study arms included infusional 5-FU/LV alone (arm A), oxaliplatin alone (arm B), and the combination of oxaliplatin and infusional 5-FU/LV(arm C). Oxaliplatin, at a dose of 85 mg/m2, was administered to patients in arms B and C intravenously over 2 hours in 250-500 ml of dextrose 5% in water (D5W) on day 1 only. A 200-mg/m2 dose of LV was administered simultaneously to arm C patients, in a separate bag using a Y-line, or alone to arm A patients, by i.v. infusion, over 2 hours. 5-FU was then administered to arms A and C patients, first as a bolus injection over 2-4 minutes at a dose of 400 mg/m2, then as a continuous infusion in 500 ml of D5W over 22 hours at a dose of 600 mg/m2. LV was repeated on day 2 of the cycle (arms A and C) followed by a 400-mg/m2 5-FU bolus and a 600-mg/m2 22-hour infusion. Treatment was repeated every 2 weeks. Response rate was the prespecified end point for accelerated approval. Time to progression (TTP) was a secondary end point. The prespecified primary comparison was between the 5-FU/LV regimen and the 5-FU/LV/ oxaliplatin combination regimen. The three arms were well balanced for patient prognostic factors. There were no complete responders. The partial response rates were 0%, 1%, and 9% for the 5-FU/LV, oxaliplatin, and oxaliplatin plus 5-FU/LV treatments, respectively (p = 0.0002, arm C versus arm A). The median times to radiographic tumor progression, based on available radiographs, were 2.7 months, 1.6 months, and 4.6 months, respectively (p < 0.0001, arm C versus arm A). Common adverse events associated with the combination treatment included peripheral neuropathy, fatigue, diarrhea, nausea, vomiting, stomatitis, and abdominal pain. Neutropenia was the major hematologic toxicity. Adverse events were similar in men and women and in patients <65 and > or =65 years of age, but older patients may have been more susceptible to dehydration, diarrhea, hypokalemia, and fatigue. Oxaliplatin in combination with infusional 5-FU/LV was approved for the treatment of patients with metastatic carcinoma of the colon or rectum whose disease has recurred or progressed during or within 6 months of completion of first-line therapy with the combination of bolus 5-FU/LV and irinotecan. Approval was based on response rate and on an interim analysis of TTP. No results are available, at this time, that demonstrate a clinical benefit, such as improvement in disease-related symptoms or survival.

U.S. Food and Drug Administration drug approval summaries: imatinib mesylate, mesna tablets, and zoledronic acid.

The purpose of this report is to summarize information on drugs recently approved by the U.S. Food and Drug Administration. Three drugs have recently been approved: Gleevec (imatinib mesylate) at a starting dose of 400 or 600 mg daily for the treatment of malignant unresectable and/or metastatic gastrointestinal stromal tumors; Mesnex (mesna) tablets as a prophylactic agent to reduce the incidence of ifosfamide-induced hemorrhagic cystitis, and Zometa (zoledronic acid) for the treatment of patients with multiple myeloma and for patients with documented bone metastases from solid tumors, in conjunction with standard antineoplastic therapy. Prostate cancer should have progressed after treatment with at least one hormonal therapy. The recommended dose and schedule is 4 mg infused over 15 minutes every 3-4 weeks. These three drugs represent three different types of drug approval: Gleevec is an accelerated approval and supplemental new drug application (NDA); Mesnex tablets represent an oral formulation of a drug approved 14 years ago as an intravenous formulation, and Zometa represents a standard NDA for a noncytotoxic, supportive-care drug. Information provided includes rationale for drug development, study design, efficacy and safety results, and pertinent literature references.