Application of Bayesian approaches in drug development: starting a virtuous cycle

The pharmaceutical industry and its global regulators have routinely used frequentist statistical methods, such as null hypothesis significance testing and p values, for evaluation and approval of new treatments. The clinical drug development process, however, with its accumulation of data over time, can be well suited for the use of Bayesian statistical approaches that explicitly incorporate existing data into clinical trial design, analysis and decision-making. Such approaches, if used appropriately, have the potential to substantially reduce the time and cost of bringing innovative medicines to patients, as well as to reduce the exposure of patients in clinical trials to ineffective or unsafe treatment regimens. Nevertheless, despite advances in Bayesian methodology, the availability of the necessary computational power and growing amounts of relevant existing data that could be used, Bayesian methods remain underused in the clinical development and regulatory review of new therapies. Here, we highlight the value of Bayesian methods in drug development, discuss barriers to their application and recommend approaches to address them. Our aim is to engage stakeholders in the process of considering when the use of existing data is appropriate and how Bayesian methods can be implemented more routinely as an effective tool for doing so.

Demographic diversity of participants in Pfizer sponsored clinical trials in the United States

The approval of new medicinal agents requires robust efficacy and safety clinical trial data demonstrated to be applicable to population subgroups. Limited data have previously been reported by drug sponsors on the topic of clinical trial diversity. In order to establish a baseline of diversity in our clinical trials that can be used by us and other sponsors, an analysis of clinical trial diversity was conducted covering race, ethnicity, sex, and age. This analysis includes Pfizer interventional clinical trials that initiated enrollment between 2011 through 2020. The data set comprises 213 trials with 103,103 US participants. The analysis demonstrated that overall trial participation of Black or African American individuals was at the US census level (14.3% vs 13.4%), participation of Hispanic or Latino individuals was below US census (15.9% vs 18.5%), and female participation was at US census (51.1% vs 50.8%). The analysis also examined the percentage of trials that achieved racial and ethnic distribution levels at or above census levels. Participant levels above census were achieved in 56.1% of Pfizer trials for Black or African American participants, 51.4% of trials for White participants, 16.0% of trials for Asian participants, 14.2% of trials for Native Hawaiian and Pacific Islander participants, 8.5% of trials for American Indian and Alaska Native participants, and 52.3% of trials for Hispanic or Latino participants. The results presented here provide a baseline upon which we can quantify the impact of our ongoing efforts to improve racial and ethnic diversity in clinical trials.

Remote Digital Monitoring for Medical Product Development

The use of digital health products has gained considerable interest as a new way to improve therapeutic research and development. Although these products are being adopted by various industries and stakeholders, their incorporation in clinical trials has been slow due to a disconnect between the promises of digital products and potential risks in using these new technologies in the absence of regulatory support. The Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium hosted a public workshop to address challenges and opportunities in this field. Important characteristics of tool development were addressed in a series of presentations, case studies, and open panel sessions. The workshop participants endorsed the usefulness of an evidentiary criteria framework, highlighted the importance of early patient engagement, and emphasized the potential impact of digital monitoring tools and precompetitive collaborations. Concerns were expressed about the lack of real‐life validation examples and the limitations of legacy standards used as a benchmark for novel tool development and validation. Participants recognized the need for novel analytical and statistical approaches to accommodate analyses of these novel data types. Future directions are to harmonize definitions to build common methodologies and foster multidisciplinary collaborations; to develop approaches toward integrating digital monitoring data with the totality of the data in clinical trials, and to continue an open dialog in the community. There was a consensus that all these efforts combined may create a paradigm shift of how clinical trials are planned, conducted, and results brought to regulatory reviews.

Use of Real-World Data to Emulate a Clinical Trial and Support Regulatory Decision Making: Assessing the Impact of Temporality, Comparator Choice, and Method of Adjustment

External controls have been primarily used in the setting of single-arm trials of rare diseases; their use in common diseases has not been readily investigated, nor is there guidance on how to best select comparators. Thus, the objective of this study was to emulate a large cardiovascular outcome trial of type 2 diabetes to compare associations of effectiveness with different comparator groups to those reported in the trial. Using the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) trial, we investigated six comparator groups using three calendar time periods (Early: 1999-2003; Later: 2004-2008, and Contemporaneous: 2009-2013) and two comparators (sulfonylureas and other second-to-third-line antidiabetic drugs). Hazard ratios (HRs) of the three-point composite cardiovascular outcome were estimated using four variations of the propensity score (adjustment, stratification, fine stratification, and matching) and compared with the LEADER trial (HR, 0.87; 95% confidence interval, 0.78-0.97). When comparing users of liraglutide with users of sulfonylureas, the HRs ranged from 0.57 to 1.03, with estimates in the early period most closely reflecting the LEADER trial (HR, 0.57-0.88). In contrast, the HRs ranged from 0.73 to 0.97 when comparing liraglutide users with users of any second-to-third-line antidiabetic drugs, although the later period generated estimates closest to the LEADER trial (HR, 0.77-0.84). Different methods of adjustment led to generally consistent HRs, aside from the fine stratification in the early period. This study highlights the complex interplay between comparator, temporality, and method of adjustment when selecting comparators using real-word data. These design choices must be considered in the design of trial emulation studies.

Regulation and Innovation: Role of Regulatory Science in Facilitating Pharmaceutical Innovation

Regulatory science is defined as science and research intended to inform decision making in a regulatory framework. This issue of Clinical Pharmacology & Therapeutics and the papers herein deal with the expansive topic of regulatory science and its role in fostering innovation and accelerating access to medicines. Regulatory health authorities, industry, and multiple stakeholders have a shared objective in advancing regulatory science to keep up with the ever-increasing pace of biomedical science.

Affairs of the Heart: Innovation in Cardiovascular Research and Development

Cardiovascular disease represents the single largest contributor to morbidity and mortality, yet the flow of therapeutic innovation is lagging. Globally, academia, industry, and regulatory agencies must work together to address this gap, and ensure new disruptive therapeutic modalities to address growing needs of patients and society.

"Threshold-crossing": A Useful Way to Establish the Counterfactual in Clinical Trials?

A central question in the assessment of benefit/harm of new treatments is: how does the average outcome on the new treatment (the factual) compare to the average outcome had patients received no treatment or a different treatment known to be effective (the counterfactual)? Randomized controlled trials (RCTs) are the standard for comparing the factual with the counterfactual. Recent developments necessitate and enable a new way of determining the counterfactual for some new medicines. For select situations, we propose a new framework for evidence generation, which we call "threshold-crossing." This framework leverages the wealth of information that is becoming available from completed RCTs and from real world data sources. Relying on formalized procedures, information gleaned from these data is used to estimate the counterfactual, enabling efficacy assessment of new drugs. We propose future (research) activities to enable "threshold-crossing" for carefully selected products and indications in which RCTs are not feasible.

From adaptive licensing to adaptive pathways: delivering a flexible life-span approach to bring new drugs to patients

The concept of adaptive licensing (AL) has met with considerable interest. Yet some remain skeptical about its feasibility. Others argue that the focus and name of AL should be broadened. Against this background of ongoing debate, we examine the environmental changes that will likely make adaptive pathways the preferred approach in the future. The key drivers include: growing patient demand for timely access to promising therapies, emerging science leading to fragmentation of treatment populations, rising payer influence on product accessibility, and pressure on pharma/investors to ensure sustainability of drug development. We also discuss a number of environmental changes that will enable an adaptive paradigm. A life‐span approach to bringing innovation to patients is expected to help address the perceived access vs. evidence trade‐off, help de‐risk drug development, and lead to better outcomes for patients.

Pharmacometrics and the transition to model-based development

As the transition to model-based drug development continues, pharmacometric analysis will have an increasingly important role across the entire life cycle of drug discovery, development, regulatory approval, and commercialization. For this reason, pharmacometrics can--and should--have an integrating function in the transformation to model-based development. This essay describes an approach for formalizing the pharmacometrics process using the disciplines encompassed by enterprise engineering.

Increased US prescription trends associated with the CDC Bacillus anthracis antimicrobial postexposure prophylaxis campaign

PURPOSE

We evaluated national outpatient antimicrobial prescription trends in relation to the first United States case of inhalational anthrax due to the intentional delivery of Bacillus anthracis (B. anthracis) spores.

METHODS

We queried IMS HEALTH's National Prescription Audit Plus7 database for two 6-month periods (July-December) in 2001 and 2000 to describe outpatient prescription trends of antimicrobials recommended during the Centers for Disease Control and Prevention's (CDC) postexposure prophylaxis campaign.

RESULTS

Overall, antimicrobial utilization for the referent 6-month time frame was greater in 2000 compared to 2001. In contrast, ciprofloxacin utilization was greater in 2001 during October, the month following the index case, increasing by more than 40% over utilization in October 2000. Similarly, doxycycline utilization increased by 30% during October/November. This corresponded to relative increases in US utilization for ciprofloxacin of approximately 160,000 prescriptions for the month of October and for doxycycline of approximately 96,000 prescriptions during October and 120,000 prescriptions for November.

CONCLUSIONS

We conclude more widespread prescribing of ciprofloxacin and doxycycline occurred in response to the first US bioterrorist-associated anthrax attacks than was warranted based upon confirmed or suspected B. anthracis exposure alone.

Concomitant risk factors in reports of torsades de pointes associated with macrolide use: review of the United States Food and Drug Administration Adverse Event Reporting System

In this case series, we examined concomitant risk factors mentioned in reports of torsades de pointes, a rare ventricular arrhythmia, that occurred in association with administration of macrolide antimicrobials (e.g., azithromycin, clarithromycin, dirithromycin, and erythromycin). Increasing age, female sex, and concomitant diseases and drug administration believed to increase risks for torsades de pointes were commonly reported.

Retrospective analysis of mortalities associated with medication errors

The types, causes, contributing factors, and patient demographics of fatal medication errors were reviewed. Case reports of medication errors from hospitals, ambulatory care settings, and patients' homes that were entered in FDA's Adverse Event Reporting System during 1993-98 were the source of information on fatal medication errors. Each report was classified using predefined criteria and a taxonomy developed by the National Coordinating Council for Medication Error Reporting and Prevention. The types, causes, contributing factors, and patient demographics were identified, and the causality of each case was assessed to prevent future fatalities. The data indicated 5,366 medication error reports. Fifty-nine reports were excluded and classified as duplicate reports or intentional overdoses. Of the remaining medication error reports, 68.2% resulted in serious patient outcomes and 9.8% were fatal. Of the 469 fatal medication error reports, 48.6% occurred in patients over 60 years. The most common types of errors resulting in patient death involved administering an improper dose (40.9%), administering the wrong drug (16%), and using the wrong route of administration (9.5%). The most common causes of errors were performance and knowledge deficits (44%) and communication errors (15.8%). Fatal medication errors accounted for approximately 10% of medication errors reported to FDA and were most frequently the result of improper dosing of the intended drug and administration of an incorrect drug. A review of case reports of medication errors from 1993 to 1998 yielded information on the most frequent causes of and contributing factors involved in fatal medication errors.

Clinical pharmacology studies in patients with renal impairment: past experience and regulatory perspectives

The objective of this report is to provide a regulatory perspective on the quality of pharmacokinetic studies in renal impairment (RI) studies submitted in support of new drug applications (NDAs) or supplements to NDAs (sNDAs) submitted to the Food and Drug Administration (FDA). Fifty-one NDA and 20 sNDA submissions reviewed between 1996 and 1997 by the Office of Clinical Pharmacology and Biopharmaceutics were evaluated for the following: (1) whether an RI study was conducted; (2) contribution of the renal clearance to the overall clearance in subjects without renal impairment; (3) degree of plasma protein binding (%PB) in subjects without renal impairment; (4) dose proportionality of single and multiple doses; (5) study design, including dosing regimen; (6) definition of renal impairment; (7) stratification of renal functions; (8) number of subjects/group; (9) data analysis and interpretation; and (10) impact on labeling. Results of the analysis indicated that 67% of the NDAs and 30% of supplemental NDAs contained RI-studies (34/51 for NDAs and 6/20 for sNDAs). No obvious differences in the pharmacokinetic characteristics (e.g., percentage excreted unchanged in urine and %PB) were observed between drugs for which RI studies were conducted versus those not conducted. Most studies conducted were designed as single dose (70%). Seventy-five percent of the studies used doses within the therapeutic dosage range of the drug. The measured 24-hour creatinine clearance was most often used to assess the renal function. Stratification of renal function ranged from one to five groups, with 6 to 8 subjects enrolled per group. In most studies conducted (38/40), data were analyzed by point estimate using ANOVA. Results of RI studies were adequately reflected in the labeling. The survey reveals that RI study design can be improved for regulatory review purposes. In part based on this analysis, the FDA has prepared a guidance that provides recommendations on the design, analysis, and impact on dosing and labeling for RI studies to include recommendations on when RI studies do not need to be performed. The guidance proposes an equivalence approach with confidence intervals, as opposed to a point estimate approach, to assess the impact of RI on systemic exposure measures.

Staphylococcus aureus isolation from the lesions, the hands, and anterior nares of patients with atopic dermatitis

Staphylococcus aureus colonization is common in atopic dermatitis (AD) and can exacerbate the disease. Some patients with atopic dermatitis may act as a reservoir for S. aureus transmission to others. This study compared S. aureus colonization in atopic dermatitis patients and their caregivers with control patients and their caregivers. Quantitative cultures were obtained from the lesions, clinically normal skin, hands, and anterior nares of 100 patients with atopic dermatitis, 100 controls with other cutaneous disorders, and 200 caregivers. The AD patients had significantly greater presence of S. aureus from lesional and clinically normal skin, as well as the hand. Significantly increased carriage of S. aureus was found in the anterior nares of caretakers of AD patients compared with control caretakers. Topical corticosteroid use did not affect recovery of S. aureus. There was a significant correlation between recovery of S. aureus from lesional skin and recovery from the anterior nares and hands. The nares and hands may be important reservoirs and vectors for autotransmission of S. aureus to lesional skin and for transmission to patients with AD.

Preadmission psychosocial screening of older orthopedic surgery patients: evaluation of a Social Work Service

A preadmission social work intervention was evaluated for impact on length of hospital stay (LOS) and patient satisfaction. Psychosocial issues related to function and post-discharge needs were assessed at an exploratory level. A modified post-test only control group design was used. Study group patients were screened before hospitalization and offered services on admission. Control group patients received standard care. Study group patients were significantly more satisfied with services but impact on length of stay was not demonstrated with one possible exception. Post-operative complications were significantly related to longer LOS; however, unlike control group patients, study group patients with complications did not have significantly longer LOS. Women and those limited in preadmission physical function were most likely to report insufficient help after discharge. A more intensive preadmission intervention is recommended to improve impact on LOS and informal support system involvement, while future outcome studies would clarify the nature of service gaps and high risk groups.

Withholding consent to lifesaving treatment: three cases

The refusal of children or their parents to consent to treatment that professionals regard as essential always results in a dilemma. Responding to such refusals demands careful and sensitive clinical and thicolegal intervention and close cooperation among professionals, in particular doctors and social workers. Since the introduction of the Children Act 1989 the number of cases in which children have withheld consent to lifesaving treatment has risen, and it is now increasingly recognised that children have a right to have their views legally represented if a local authority or health authority seeks a court's leave to carry out treatment. Professionals have to consider which legal route, under either the Children Act or the Mental Health Act, is likely to be best for the individual child.

Anogenital warts in children. Clinical and virologic evaluation for sexual abuse

Seventy-three children with anogenital warts were examined for sexual abuse during a 2-year period. Our data suggest that nonsexual transmission is common, particularly in children under 3 years of age. Approximately 25% of these children were younger than age 1 year, and another 50% were between the ages of 1 and 3 years. No evidence of sexual abuse was detected in 66 children.

Cockarde nevus: a case report and review of the literature

Benign acquired melanocytic nevi usually display an even and uniform architecture and coloration easily recognized by the dermatologist. The cockarde nevus, a variant of the melanocytic nevus, is an exception. It displays a targetlike morphology with histologic characteristics of a compound nevus. We believe because the lesion has been rarely reported in the American literature, it is often mistaken in this country for a dysplastic nevus.