Impact of pharmacometrics on drug approval and labeling decisions: A survey of 42 new drug applications

The value of quantitative thinking in drug development and regulatory review is increasingly being appreciated. Modeling and simulation of data pertaining to pharmacokinetic, pharmacodynamic, and disease progression is often referred to as the pharmacometrics analyses. The objective of the current report is to assess the role of pharmacometrics at the US Food and Drug Administration (FDA) in making drug approval and labeling decisions. The New Drug Applications (NDAs) submitted between 2000 and 2004 to the Cardio-renal, Oncology, and Neuropharmacology drug products divisions were surveyed. For those NDA reviews that included a pharmacometrics consultation, the clinical pharmacology scientists ranked the impact on the regulatory decision(s). Of about a total of 244 NDAs, 42 included a pharmacometrics component. Review of NDAs involved independent, quantitative evaluation by FDA pharmacometricians, even when such analysis was not conducted by the sponsor. Pharmacometric analyses were pivotal in regulatory decision making in more than half of the 42 NDAs. Of the 14 reviews that were pivotal to approval related decisions, 5 identified the need for additional trials, whereas 6 reduced the burden of conducting additional trials. Collaboration among the FDA clinical pharmacology, medical, and statistical reviewers and effective communication with the sponsors was critical for the impact to occur. The survey and the case studies emphasize the need for early interaction between the FDA and sponsors to plan the development more efficiently by appreciating the regulatory expectations better.     

美国食品药品监督管理局接受不确定性:治疗多重耐药的人类免疫缺陷病毒感染的单克隆抗体加速获批

未满足的临床需求影响着临床试验的科学设计和药品审批的监管决策。美国食品药品监督管理局(FDA)于2018年批准了全球首个抗艾滋病的单克隆抗体艾巴利珠单抗(ibalizumab)用于治疗多重耐药的人类免疫缺陷病毒(HIV)感染。该药物的上市批准主要基于1项纳入40例患者的Ⅲ期单臂的简化临床试验。这体现了面对抗HIV多重耐药的未满足的医疗需求,FDA所做的风险和获益的权衡,以及采取的科学、灵活的审评态度。本文以此药为例,讨论了简化临床试验设计和FDA在审评中的监管考量,以期对我国药品审评的制度改革有所裨益。     

Application of Pharmacometric Analysis in the Design of Clinical Pharmacology Studies for Biosimilar Development

This article provides an overview of four case studies to demonstrate the utility of pharmacometric analysis in biosimilar development to help design sensitive clinical pharmacology studies for the demonstration of biosimilarity. The two major factors that determine the sensitivity of a clinical pharmacokinetic/pharmacodynamic (PK/PD) study to demonstrate biosimilarity are the size of the potential difference to be detected (signal) and the inter-subject variability (noise), both of which can be characterized and predicted using pharmacometric approaches. To maximize the chance to detect any potential difference between the proposed biosimilar and the reference drug, the dose selected for the clinical pharmacology study should fall on the steep part of the dose-response curve. Pharmacometric analysis can be used to characterize the dose-response relationship using PD- or PK/PD-linked models. The understanding of the PD endpoints in terms of dynamic range of the response and the location of the studied dose on the dose-response curve can provide strategic advantage in the trial design. To reduce the inter-subject variability (noise), pharmacometric analysis can help avoid high variability associated with low doses, and decrease variability by controlling certain covariates in the inclusion/exclusion criteria. Pharmacometric analysis also can help select or justify margins for the equivalence test of PD endpoints. Pharmacometric analysis will assume an ever-increasing role in the clinical development of biosimilar drugs, as it helps to ensure that sufficient sensitivity is built into the study design to detect potential PK and PD differences.     

The impact of FDA guidance on pharmacogenomic data submissions on drug development

After a long wait, the US Food and Drug Administration (FDA) finally released the much anticipated 'Guidance on Pharmacogenomic Data Submissions on Drug Development' in March 2005, but what impact will this have on the drug industry as a whole? It is becoming increasingly apparent that the field of pharmacogenomics can add value to both clinical trial design and the drug development process, but uptake by the pharmaceutical industry has so far been variable between companies. The opinion of the FDA is that the use of pharmacogenomics in drug development is a 'good thing' and one that it wishes to promote, hence, this new guidance is designed to assist drug companies to adopt pharmacogenomic technology in clinical development, and covers both targeted and exploratory aspects. While targeted pharmacogenomics must be included as part of any regulatory submission, exploratory approaches may be submitted voluntarily with assurances from the FDA that any such submissions will not be used to make regulatory decisions. With this regulatory framework now in place it is only a matter of time before it is known how the industry reacts and the impact it will have on drug development.     

Summary of the 34th annual meeting of the Drug Information Association

A variety of issues relating to clinical aspects of drug development were discussed at the 34(th) annual meeting of the Drug Information Association. Among the topics covered at this conference were the following: 1, development of CNS compounds; 2, the Common Technical Document (CTD); and 3, labelling of drugs for use in pregnancy. Issues surrounding the development of CNS compounds were discussed by regulatory authorities from the USA and Europe. In almost all aspects covered, the regulatory requirements for approval in Europe appear to be consistent with those in the USA. Efforts aimed at developing a CTD are ongoing under the auspices of the ICH. The goal of this effort is to develop a common technical information package that can be submitted to regulatory authorities in the USA, the EU and Japan. It is recognised, however, that a number of sections of regulatory submissions will remain outside of the CTD. New initiatives in the labelling of drugs for use in pregnancy in the USA were reviewed. These efforts are being led by the Pregnancy Labeling Task Force of the USA FDA. The overall goal of this effort is to more clearly define by labelling, the relative risks of pharmaceutical agents that must be administered to pregnant women.     

Summary of the 34th Annual Meeting of the Drug Information Association

A variety of issues relating to clinical aspects of drug development were discussed at the 34^th annual meeting of the Drug Information Association. Among the topics covered at this conference were the following: 1, development of CNS compounds; 2, the Common Technical Document (CTD); and 3, labelling of drugs for use in pregnancy. Issues surrounding the development of CNS compounds were discussed by regulatory authorities from the USA and Europe. In almost all aspects covered, the regulatory requirements for approval in Europe appear to be consistent with those in the USA. Efforts aimed at developing a CTD are ongoing under the auspices of the ICH. The goal of this effort is to develop a common technical information package that can be submitted to regulatory authorities in the USA, the EU and Japan. It is recognised, however, that a number of sections of regulatory submissions will remain outside of the CTD. New initiatives in the labelling of drugs for use in pregnancy in the USA were reviewed. These efforts are being led by the Pregnancy Labeling Task Force of the USA FDA. The overall goal of this effort is to more clearly define by labelling, the relative risks of pharmaceutical agents that must be administered to pregnant women.     

How Modeling and Simulation Have Enhanced Decision Making in New Drug Development

The idea of model-based drug development championed by Lewis Sheiner, in which pharmacostatistical models of drug efficacy and safety are developed from preclinical and available clinical data, offers a quantitative approach to improving drug development and development decision-making. Examples are presented that support this paradigm. The first example describes a preclinical model of behavioral activity to predict potency and time-course of response in humans and assess the potential for differentiation between compounds. This example illustrates how modeling procedures expounded by Lewis Sheiner provided the means to differentiate potency and the lag time between drug exposure and response and allow for rapid decision making and dose selection. The second example involves planning a Phase 2a dose-ranging and proof of concept trial in Alzheimer’s disease (AD). The issue was how to proceed with the study and what criteria to use for a go/no go decision. The combined knowledge of AD disease progression, and preclinical and clinical information about the drug were used to simulate various clinical trial scenarios to identify an efficient and effective Phase 2 study. A design was selected and carried out resulting in a number of important learning experiences as well as extensive financial savings. The motivation for this case in point was the “Learn-Confirm” paradigm described by Lewis Sheiner. The final example describes the use of Pharmacokinetic and Pharmacodynamic (PK/PD) modeling and simulation to confirm efficacy across doses. In the New Drug Application for gabapentin, data from two adequate and well-controlled clinical trials was submitted to the Food and Drug Administration (FDA) in support of the approval of the indication for the treatment of post-herpetic neuralgia. The clinical trial data was not replicated for each of the sought dose levels in the drug application presenting a regulatory dilemma. Exposure response analysis submitted in the New Drug Application was applied to confirm the evidence of efficacy across these dose levels. Modeling and simulation analyses showed that the two studies corroborate each other with respect to the pain relief profiles. The use of PK/PD information confirmed evidence of efficacy across the three studied doses, eliminating the need for additional clinical trials and thus supporting the approval of the product. It can be speculated that the work by Lewis Sheiner reflected in the FDA document titled “Innovation or Stagnation: Challenge and Opportunity on the Critical Path to New Medical Products” made this scientific approach to the drug approval process possible.     

Product selection, bioequivalence, and therapeutic equivalence: the generic drug market

Pharmacists are continually faced with drug product selection decisions. When is a generic drug product equivalent to the innovator product and, thus, a suitable candidate for generic substitution? The FDA policy has been that only drug products that are therapeutic equivalents are candidates for product selection decisions. This paper outlines the regulatory and scientific framework for the FDA's policies and requirements for generic drug products. The history and current status of the Drug Efficacy Study Implementation (DESI) project is described. Originally begun in 1966 as a review of about 3,400 drug products, the review in mid-1983 is more than 90% complete, but its impact has already affected more than 7,000 marketed drug products. The therapeutic equivalence policy and the manner in which decisions on therapeutic equivalence are communicated are reviewed. Regulatory policies for the approval of generic drug products are reviewed and specific litigation challenging the rights of generic drug manufacturers to produce generic "look-alikes" and challenging the FDA's policy that a generic drug product is a new drug requiring an approved New Drug Application for marketing is discussed. The conclusion reached is that the evaluation of regulatory requirements and science is leading to a point where all generic drug products will be known to be safe, effective and therapeutically equivalent, and pharmacists can be optimistic about the quality of products in the generic drug market.     

The US FDAs withdrawal of the breast cancer indication for Avastin (bevacizumab)

On November 18, 2011, the US Food and Drug Administration (US FDA) announced that breast cancer indication for Avastin (bevacizumab) had been withdrawn after concluding that the drug has not been shown to be safe and effective for the treatment of breast cancer. The specific indication that was withdrawn was for the use of bevacizumab in metastatic breast cancer, with paclitaxel for the treatment of patients who have not received chemotherapy for metastatic HER2-negative breast cancer.The US FDAs decision has been met with emotion and confusion among the public and health professionals. The purpose of this article is to review the regulatory history of bevacizumab for breast cancer and to examine the scientific evidence that led to the approval and subsequent withdrawal of this indication. Bevacizumab also provides the opportunity to illustrate the value of free publicly available US FDA reviews that may contain rigorously reviewed unpublished data and analyses and to contrast the decisions made in the US and Europe about bevacizumab and breast cancer.     

Integration of Pharmacometric and Statistical Analyses Using Clinical Trial Simulations to Enhance Quantitative Decision Making in Clinical Drug Development

This article outlines a general framework in which clinical trial simulations (CTS) are employed integrating both pharmacometric and statistical analyses to support trial design and quantitative decision making in drug development. Specifically, predictive pharmacometric models are used as data-generation models to simulate data, while data-analytic models as specified in the statistical analysis plan are used to analyze the simulated data and to apply a quantitative data-analytic decision rule. Various probability metrics including probability of achieving the target value, probability of success, and probability of a correct decision are proposed to support study design recommendations and quantitative decision-making. A case study is presented to illustrate the CTS methods and procedures described in this article.     

Regulatory Decision‐Making in the United States Based on a Single Pivotal Clinical Study: Principles and Precedents

The concept of regulatory approval in the United States based on substantial evidence from a single adequate and well‐controlled clinical study is not a new or radical concept. Appropriate discussions and developmental milestone meetings between sponsors and U.S. Food and Drug Administration (FDA) have provided a means to reach a shared understanding of specific situations where a single adequate and well‐controlled study may yield substantial evidence to enable a regulatory approval in the United States. FDA's issuance of its final guidance document on evidence of clinical effectiveness brought additional attention to this topic. The basis in US law, regulations, and guidance for regulatory decision making based on a single adequate and well‐controlled trial is reviewed. Further, to illustrate practical implementation of these provisions, this paper summarizes a number of examples of situations in which a single clinical study was the basis for approval by FDA. These examples were grouped into categories for the purpose of illuminating the patterns of established regulatory precedents. Sufficient examples were available to show logical groupings of experiences to demonstrate circumstances in drug development where there are reasonable precedents for use of a single adequate and well‐controlled trial for regulatory decision making. Regulatory decision‐making based on a single adequate and well‐controlled trial appears to be a well‐accepted approach to attaining approval for 1) use of a product for a new indication where patients attain a significant reduction in morbidity or mortality (or both) with treatment with a drug that was previously approved for a related indication, 2) a new dosage regimen for a previously approved product, and 3) a Supplemental Application seeking traditional approval of a product based on confirmatory evidence of clinical efficacy for a product subject to accelerated approval. Not surprisingly, reliance on a single adequate and well‐controlled trial as the basis for approval of an original NDA or BLA for a new chemical entity or new biologic has been infrequent and typically limited to special situations where patients are refractory to other available therapies or where no alternative therapy exists. The examples presented here illustrate a range of practical experiences where a single adequate and well‐controlled trial has successfully provided the primary basis for regulatory approval in the United States. This information should assist developers of drugs and biologics in their consideration of alternative approaches to development and registration of new products and new indications.     

Application of advanced in silico methods for predictive modeling and information integration

INTRODUCTION: In silico predictive methods are well-known tools to the drug discovery process. In recent years, these tools have become of strategic interest to regulatory authorities to support risk-based approaches and to complement, and potentially strengthen evidence when considering product quality and safety of human pharmaceuticals. AREAS COVERED: This editorial reviews how chemically intelligent systems and computational models using structure-based assessments are important for providing predictive data on drug toxicity and safety liabilities considered at the FDA. The example of regulatory interest in application of in silico systems for mutagenicity predictions of drug impurities is discussed. EXPERT OPINION: The importance of information integration is emphasized toward the application of in silico predictive methods and enhancing data mining capabilities for safety signal detection. Modeling for cardiovascular drug safety based on human clinical trial data is one area of active testing of predictive technologies at the FDA. The FDA has taken appropriate steps in its strategies and initiatives aimed to enhance and support innovation for regulatory science and medical product development by developing and implementing the use of in silico predictive models and medical toxicity databases. This science priority area will ultimately help improve and protect public health.     

Treprostinil sodium Pharmacia

United Therapeutics Corp (UTC) is developing treprostinil sodium (Remodulin, UT-15), a stable structural analog of prostacyclin, for the potential treatment of primary pulmonary (arterial) hypertension (PAH), peripheral vascular disease (PVD) and other cardiovascular conditions [327593], including critical limb ischemia (CLI) [412483]. In August 2000, UTC submitted the initial, non-clinical sections of an NDA for the treatment of pulmonary hypertension [378906]. Treprostinil, which had previously been designated as an Orphan Drug, was also awarded Priority Review status by the US FDA in October 2000 [385864], [386271]. In December 2000, UTC agreed with the FDA that the NDA for treprostinil did not need to be presented to the Cardiovascular and Renal Drugs Advisory Committee, which was expected to allow UTC and the FDA to work towards the 6-month Priority Review timeline [393888]. On August 9, 2001, the advisory committee recommended approval of treprostinil and UTC refiled the NDA on the same day [418682]. In February 2002, the FDA issued an approvable letter for treprostinil injection for the treatment of PAH. The FDA proposed drug labeling for PAH consistent with the treatment of both primary and secondary pulmonary hypertension in patients with New York Heart Association (NYHA) Class II-IV symptoms. The approvable letter also stated that the FDA intended to approve treprostinil with a requirement that UTC subsequently conduct a post-marketing controlled clinical trial to verify and further describe the drug's clinical benefit [439278]. In February 2001, UTC submitted a marketing authorization application (MAA) in France for approval of treprostinil for the treatment of PAH. Upon approval of the MAA, UTC planned to file for Mutual Recognition in other European countries and was also preparing similar submissions to non-European countries [391986], [397958]. By early 2001, phase II trials of treprostinil for the treatment of CLI were underway [412483]. In March 2001, the company was planning a phase III pivotal study in late-stage PVD by the end of 2001 [424180]. In April 2000, UTC was issued US-06054486 for the method of treating PVD with treprostinil [364130]. In February 2000, UTC entered into an agreement with Paladin Labs for the exclusive Canadian distribution of treprostinil for the remainder of clinical trials and after regulatory approvals [357302]. In November 2000, UTC and Antigen Pharmaceuticals entered into a strategic alliance for the distribution of treprostinil in the UK and Ireland [390157]. In November 2000, Deutsche Banc Alex Brown predicted a sales potential of US $250 million to US $350 million [418736]. In August 2001, Merril Lynch predicted sales of US $10 million to $20 million in 2002 [420652].     

OvaRex (AltaRex)

AltaRex is developing OvaRex (B43.13), a monoclonal antibody vaccine, for the potential treatment of ovarian cancer. Additionally, immunotherapy may be possible in other cancers expressing the CA125 antigen, such as breast and lung cancers. AltaRex plans to file a BLA for OvaRex with the FDA in late 2001 and for Canadian and European regulatory submissions thereafter, with possible commercialization in 2002 [365081,377828,398528]. In December 2000, AltaRex engaged US Oncology to participate in the company's phase II trial for the 'watchful waiting' stage of ovarian cancer. The US Oncology relationship will bring over 20 satellite sites to the OvaRex study, in addition to 13 sites that had already begun enrolling patients [394604,384676,365081]. In 1997, AltaRex commenced a multicenter, placebo-controlled, double-blind, randomized phase IIb trial in the US for advanced ovarian cancer [230067,331744,344248]. In the following year, AltaRex submitted the IND to the FDA for this trial [303667]. Complete analysis of the data is expected by the first half of 2001 [291312,310071,344248]. If an NDA is filed before the end of 2001, approval by mid-2002 is possible [344248]. OvaRex has been awarded Fast Track designation for advanced ovarian cancer [310071] and Orphan Drug status in the US [230067].     

Completeness Assessment of Type II Active Pharmaceutical Ingredient Drug Master Files under Generic Drug User Fee Amendment: Review Metrics and Common Incomplete Items

Under the Generic Drug User Fee Amendments (GDUFA) of 2012, Type II active pharmaceutical ingredient (API) drug master files (DMFs) must pay a user fee and pass a Completeness Assessment (CA) before they can be referenced in an Abbreviated New Drug Application (ANDA), ANDA amendment, or ANDA prior approval supplement (PAS). During the first year of GDUFA implementation, from October 1, 2012 to September 30, 2013, approximately 1,500 Type II API DMFs received at least one cycle of CA review and more than 1,100 Type II DMFs were deemed complete and published on FDA’s “Available for Reference List”. The data from CA reviews were analyzed for factors that influenced the CA review process and metrics, as well as the areas of DMF submissions which most frequently led to an incomplete CA status. The metrics analysis revealed that electronic DMFs appear to improve the completeness of submission and shorten both the review and response times. Utilizing the CA checklist to compile and proactively update the DMFs improves the chance for the DMFs to pass the CA in the first cycle. However, given that the majority of DMFs require at least two cycles of CA before being deemed complete, it is recommended that DMF fees are paid 6 months in advance of the ANDA submissions in order to avoid negatively impacting the filling status of the ANDAs.     

Pharmacometrics in dose finding or dose optimization of anti-retroviral and anti-tubercular drugs

Drug development continues to be time consuming, expensive and less efficient, while drug therapy is often administered at suboptimal levels. This is particularly true with anti-infectives for HIV and tuberculosis. The application of pharmacometric principles and models to drug development and pharmacotherapy will improve the drug approval process and selection of optimal dosage regimens or therapeutic combinations. In this review we mainly focus on the utilities of pharmacometrics in the dose selections of anti-retroviral and anti-tubercular drugs. We will examine how pharmacometrics have been useful in the area of dose selections, preclinical to clinical scaling, subpopulation selections, combination therapies, adherence assessments, and resistance prevention dosing strategies.     

Knowledge management for efficient quantitative analyses during regulatory reviews

Knowledge management comprises the strategies and methods employed to generate and leverage knowledge within an organization. This report outlines the activities within the Division of Pharmacometrics at the US FDA to effectively manage knowledge with the ultimate goal of improving drug development and advancing public health. The infrastructure required for pharmacometric knowledge management includes provisions for data standards, queryable databases, libraries of modeling tools, archiving of analysis results and reporting templates for effective communication. Two examples of knowledge management systems developed within the Division of Pharmacometrics are used to illustrate these principles. The benefits of sound knowledge management include increased productivity, allowing reviewers to focus on research questions spanning new drug applications, such as improved trial design and biomarker development. The future of knowledge management depends on the collaboration between the FDA and industry to implement data and model standards to enhance sharing and dissemination of knowledge.     

Knowledge management for efficient quantitative analyses during regulatory reviews

Knowledge management comprises the strategies and methods employed to generate and leverage knowledge within an organization. This report outlines the activities within the Division of Pharmacometrics at the US FDA to effectively manage knowledge with the ultimate goal of improving drug development and advancing public health. The infrastructure required for pharmacometric knowledge management includes provisions for data standards, queryable databases, libraries of modeling tools, archiving of analysis results and reporting templates for effective communication. Two examples of knowledge management systems developed within the Division of Pharmacometrics are used to illustrate these principles. The benefits of sound knowledge management include increased productivity, allowing reviewers to focus on research questions spanning new drug applications, such as improved trial design and biomarker development. The future of knowledge management depends on the collaboration between the FDA and industry to implement data and model standards to enhance sharing and dissemination of knowledge.     

Assessing tumor-related signs and symptoms to support cancer drug approval

Cancer causes premature death and significant, often devastating, symptoms. While prolongation of survival is an obvious end point for new cancer drug approval, the US Food and Drug Administration (FDA) has also utilized end points that evaluate patient symptoms. In this article we discuss the end points, evidence, and analyses supporting cancer drug approvals based on evaluations of tumor-related signs and symptoms. With advice from the Oncologic Drug Advisory Committee (ODAC) in the late 1970s and early 1980s, FDA determined that acceptable end points for cancer drug approval were survival or an improvement in the quality of a patient's life, e.g., an improvement in tumor-related symptoms. This article summarizes 15 FDA cancer drug approvals based on patient symptom assessments and/or physical signs (thought to represent symptomatic improvement) as the primary evidence of effectiveness. These include painful bone events (three cases), cosmetic improvement in Kaposi's sarcoma and cutaneous T-cell lymphoma (six cases), the consequences (decreased transfusions, etc.) of long-duration responses in leukemias and lymphomas (two cases), relief of pulmonary or esophageal obstruction (two cases), and one case each of symptom benefit in pancreatic cancer (also associated with survival benefit) and pulmonary symptom benefit in lung cancer. An instructive example of an individual patient benefit end point is discussed, though it did not lead to a drug approval (the cisplatin-epinephrine gel application). Improved trial designs and analysis plans may allow greater reliance on morbidity assessments to support future cancer drug approvals. Drug sponsors are encouraged to include symptom assessments in cancer clinical trials and to perform further research to improve symptom-assessment methods. The FDA routinely meets with sponsors at End of Phase 2 Meetings to discuss drug development plans and the design of phase 3 trials. We encourage sponsors to request special protocol assessments (SPA) after meeting with the FDA to get written confirmation of the adequacy of plans for assessing cancer morbidity and quality of life, including protocols, end points, statistical analysis plans, and draft case report forms.     

Applications of In Vitro–In Vivo Correlations in Generic Drug Development: Case Studies

In vitro–in vivo correlation (IVIVC) is a predictive mathematical model describing the relationship between an in vitro property and a relevant in vivo response. The main objective of an IVIVC is to serve as a surrogate for human bioequivalence (BE) studies, which may reduce the number of BE studies performed during the initial approval process as well as with certain scale-up and postapproval changes. The US Food and Drug Administration (FDA) published a regulatory guidance related to development, evaluation, and applications of IVIVC for extended-release (ER) oral dosage forms in September 1997. Despite the publication of this guidance, the deficiencies related to IVIVC are still identified by the Division of Bioequivalence in the process of Abbreviated New Drug Application (ANDA) review. Thus, the main objective of this article is to present the most commonly occurring deficiencies associated with IVIVCs via selected case studies from the ANDAs for oral ER drug products only. We searched internal FDA databases from January 1996 to December 2014 to identify the ANDAs for proposed generic oral ER drug products containing IVIVC. Only 14 ANDA submissions had IVIVC data, and most were not acceptable. Only one ANDA submission included adequate information related to IVIVC data enabling the completion of BE review within first review cycle. It is hoped that awareness of the deficiencies presented in our article would help the generic drug applicants to submit complete and appropriate information related to IVIVC data, ultimately, resulting in a more timely approval of ANDAs.KEY WORDS: bioequivalence, extended-release drug products, generics, IVIVC, SUPAC