BOB: Bayesian optimal design for biosimilar trials with co-primary endpoints

For regulatory approval of a biosimilar product, extensive evaluations should be performed by rigorous clinical trials to establish the similarity between the reference product and the proposed biosimilar in terms of both efficacy and safety. Existing designs for biosimilar trials often use a single primary efficacy endpoint in trial monitoring, and then separately evaluate the safety of the biosimilar product in a secondary analysis at the trial completion. However, ignoring the safety endpoint and the correlation between safety and efficacy in trial monitoring may lead to a high false positive rate, or it may delay the termination of the trial when dissimilarity in safety is early detected. We propose a Bayesian optimal design for biosimilar trials by incorporating both safety and efficacy endpoints in a unified framework. Based on a Bayesian joint safety and efficacy model, we sequentially use a so-called Bayesian biosimilar probability to make go/no-go decisions. We calibrate the Bayesian design to maximize the statistical power while maintaining the frequentist type I error rate at the nominal level. We carry out extensive simulation studies to show that the design has desirable performance in terms of the false positive rate and the average sample size. We also apply the proposed design to a biosimilar trial evaluating a ranibizumab product.

Knowledge, Attitude, and Practice Towards Biosimilars and Interchangeable Products: A Prescriptive Insight by the Pharmacists

Background

Pharmacists being the drug experts need to be well aware of the applied handling of biosimilar medicines (BSMs). They are an integral educator, trailblazer, and advocate of biosimilar integration across all clinical settings. Therefore, the current study was conducted to assess the pharmacists’ knowledge, attitude, and practices of integrating BSMs into clinical practice.

Methods

The cross-sectional study was conducted from August 2019 to November 2019. The community pharmacies, clinical and academic settings in Karachi were approached for gathering the responses of pharmacists towards BSMs and interchangeable products using a 30-item survey form. Pearson correlation and independent sample t-test were used to identify the relationship among independent variables and the responses, considering p values <0.05 as statistically significant.

Results

Overall, there were 305 survey forms used with a response rate of 87.14%. More than 80% of the respondents have good knowledge about the definition, characteristics, safety and efficacy, compatibility, cost issues, and utilization of BSMs. Around half of the respondents (48.9%, [95% CI 46.6–51.2]) were confident in using BSMs in clinical practice. However, they were concerned about the BSM’s safety profile (45.2%, [95% CI 42.1–48.3]), quality (30.2%, [95% CI 28.3–32.1]), and efficacy issues (32.3%, [95% CI 31.2–37.5]).

Conclusion

The findings revealed that pharmacists were well informed about the BSMs. However, some of the responses to the attitude demonstrated a lack of understanding of the application of that knowledge. The respondents persuaded that advanced patterns of diseases, product marketing stipulations, and need for better patient care drives higher demand for developing BSMs and were enthusiastic about gaining more insight to integrate BSMs into routine clinical practice.

Use of a two-sided tolerance interval in the design and evaluation of biosimilarity in clinical studies

In assessing biosimilarity between two products, the question to ask is always "How similar is similar?" Traditionally, the equivalence of the means between products is the primary consideration in a clinical trial. This study suggests an alternative assessment for testing a certain percentage of the population of differences lying within a prespecified interval. In doing so, the accuracy and precision are assessed simultaneously by judging whether a two-sided tolerance interval falls within a prespecified acceptance range. We further derive an asymptotic distribution of the tolerance limits to determine the sample size for achieving a targeted level of power. Our numerical study shows that the proposed two-sided tolerance interval test controls the type I error rate and provides sufficient power. A real example is presented to illustrate our proposed approach.

Generic Substitution of Orphan Drugs for the Treatment of Rare Diseases: Exploring the Potential Challenges

Generic drugs are important components of measures introduced by healthcare regulatory authorities to reduce treatment costs. In most patients and conditions the switch from a branded drug to its generic counterpart is performed with no major complications. However, evidence from complex diseases suggests that generic substitution requires careful evaluation in some settings and that current bioequivalence criteria may not always be adequate for establishing the interchangeability of branded and generic products. Rare diseases, also called orphan diseases, are a group of heterogeneous diseases that share important characteristics: in addition to their scarcity, most are severe, chronic, highly debilitating, and often present in early childhood. Finding a treatment for a rare disease is challenging. Thanks to incentives that encourage research and development programs in rare diseases, several orphan drugs are currently available. The elevated cost of orphan drugs is a highly debated issue and a cause of limited access to treatment for many patients. As patent protection and the exclusivity period of several orphan drugs will expire soon, generic versions of orphan drugs should reach the market shortly, with great expectations about their impact on the economic burden of rare diseases. However, consistent with other complex diseases, generic substitution may require thoughtful considerations and may be even contraindicated in some rare conditions. This article provides an overview of rare disease characteristics, reviews reports of problematic generic substitution, and discusses why generic substitution of orphan drugs may be challenging and should be undertaken carefully in rare disease patients.

Developing the Totality of Evidence for Biosimilars: Regulatory Considerations and Building Confidence for the Healthcare Community

Biosimilars are highly similar versions of approved branded biologics. Unlike generics, they are not exact replicas of reference products. Minor differences between biosimilars and reference products in some aspects are expected; likewise, biosimilar products will differ from each other. The objective of this review is to discuss the challenges associated with the development and approval of biosimilar products that are unique because of their complex structure and specialized manufacturing processes, which can impact not only efficacy but also immunogenicity and safety. Regulatory guidelines recommend a totality-of-evidence approach focused on stepwise development that involves demonstration of structural similarity and functional equivalence. Structural and functional characteristics of the proposed biosimilar are compared with the reference product; similarity of these functions forms the foundation of the biosimilar development program, including potential animal studies, a human pharmacokinetics/pharmacodynamics equivalence study, and a clinical study to confirm similar efficacy, safety, and immunogenicity. The clinical study should be performed in a sensitive population using appropriate endpoints to allow detection of any clinically meaningful differences between the biosimilar and the reference product if such differences exist. In conclusion, development of biosimilars is focused on the minimization of potential differences between the proposed biosimilar and reference product and the establishment of a robust manufacturing process to consistently produce a high-quality biosimilar product.

Biosimilars: what the dermatologist should know

Biosimilars are highly similar versions of approved branded biologics. In contrast to generics, which are identical copies of the originator medicines, biosimilars are considered unique but related molecules that differ from the originator reference product as well as from each other. Owing to the complexity of biologic medicines, such as therapeutic monoclonal antibodies, minor differences between biosimilars and the reference products are acceptable provided these differences do not result in any clinically meaningful differences in safety or efficacy. In addition, minor changes in structure and function may occur over time in originator biologic products as a result of alterations in production materials (e.g. cell lines), processes or conditions. The developmental process for biosimilars focuses on a 'totality of evidence' approach that emphasizes a stepwise investigational process, including comprehensive structural, functional, pharmacologic and clinical assessment for similarity. The goal of the phase 3 clinical development programme for a biosimilar is not to establish efficacy, per se, but to demonstrate that there are no clinically meaningful differences between the proposed biosimilar and the reference product. The requirement to show clinical similarity informs biosimilar study design, including the selection of the patient population, disease state (indication), study endpoints and statistical methods. Based on the clinical trial results in a representative patient population, results may be extrapolated to other indications provided scientific justification is demonstrated based on, among other things, similar mechanism of action in the extrapolated indications. This review presents the current state of knowledge with respect to biosimilars. We aim to provide the practising clinician with a working knowledge of biosimilars as well as provide some practical guidance on their use and potential benefits in treating dermatologic diseases.

Quality Issues Identified During the Evaluation of Biosimilars by the European Medicines Agency's Committee for Medicinal Products for Human Use

The aim of this study was to identify trends in deficiencies raised during the EU evaluation of the quality part of dossiers for marketing authorisation applications of biosimilar medicinal products. All adopted day 120 list of questions on the quality module of 22 marketing authorisation applications for biosimilars submitted to the European Medicines Agency and concluded by the end of October 2015 was analysed. Frequencies of common deficiencies identified were calculated and summarised descriptions included. Frequencies and trends on quality deficiencies were recorded and presented for 22 biosimilar applications. Thirty-two 'major objections' for 9 products were identified from 14 marketing authorisation applications with 15 raised for drug substance and 17 for drug product. In addition, 547 'other concerns' for drug substance and 495 for drug product were also adopted. The frequencies and trends of the identified deficiencies together with their impact were discussed from a regulatory perspective and how these impact key manufacturing processes and key materials used in the production of biosimilars. This study provides an insight to the regulatory challenges prospective companies need to consider when developing biosimilars; it also helps elucidate common pitfalls in the development and production of biosimilars and in the submission of dossiers for their marketing authorisations. The results are expected to be of interest to pharmaceutical companies but also to regulators to obtain consistent information on medicinal products based on transparent rules safeguarding the necessary pharmaceutical quality of medicinal products.

On the glycosylation aspects of biosimilarity

The recent expiration of several protein therapeutics opened the door for biosimilar development. Biosimilars are biologic medical products that are similar but not identical copies of already-authorized protein therapeutics. Critical quality attributes (CQA), such as post-translational modifications of recombinant biotherapeutics, are important for the clinical efficacy and safety of both the innovative biologics and their biosimilar counterparts. Here, we summarize biosimilarity CQAs, considering the regulatory guidelines and the statistical aspects (e.g., biosimilarity index) and then discuss glycosylation as one of the important attributes of biosimilarity. Finally, we introduced the 'Glycosimilarity Index', which is based on the averaged biosimilarity criterion.

A Calibrated Power Prior Approach to Borrow Information from Historical Data with Application to Biosimilar Clinical Trials

A biosimilar refers to a follow-on biologic intended to be approved for marketing based on biosimilarity to an existing patented biological product (i.e., the reference product). To develop a biosimilar product, it is essential to demonstrate biosimilarity between the follow-on biologic and the reference product, typically through two-arm randomization trials. We propose a Bayesian adaptive design for trials to evaluate biosimilar products. To take advantage of the abundant historical data on the efficacy of the reference product that is typically available at the time a biosimilar product is developed, we propose the calibrated power prior, which allows our design to adaptively borrow information from the historical data according to the congruence between the historical data and the new data collected from the current trial. We propose a new measure, the Bayesian biosimilarity index, to measure the similarity between the biosimilar and the reference product. During the trial, we evaluate the Bayesian biosimilarity index in a group sequential fashion based on the accumulating interim data, and stop the trial early once there is enough information to conclude or reject the similarity. Extensive simulation studies show that the proposed design has higher power than traditional designs. We applied the proposed design to a biosimilar trial for treating rheumatoid arthritis.

Avoiding ambiguity with the Type I error rate in noninferiority trials

This review article sets out to examine the Type I error rates used in noninferiority trials. Most papers regarding noninferiority trials only state Type I error rate without mentioning clearly which Type I error rate is evaluated. Therefore, the Type I error rate in one paper is often different from the Type I error rate in another paper, which can confuse readers and makes it difficult to understand papers. Which Type I error rate should be evaluated is related directly to which paradigm is employed in the analysis of noninferiority trial, and to how the historical data are treated. This article reviews the characteristics of the within-trial Type I error rate and the unconditional across-trial Type I error rate which have frequently been examined in noninferiority trials. The conditional across-trial Type I error rate is also briefly discussed. In noninferiority trials comparing a new treatment with an active control without a placebo arm, it is argued that the within-trial Type I error rate should be controlled in order to obtain approval of the new treatment from the regulatory agencies. I hope that this article can help readers understand the difference between two paradigms employed in noninferiority trials.

Statistical assessment of biosimilarity based on the relative distance between follow-on biologics for binary endpoints

A new three-arm parallel design was recently proposed to investigate the biosimilarity between a biological product and a reference product by using the relative distance. The purpose of this article is to extend their results to binary endpoints for three popular metrics: the risk difference, the log relative risk, and the log odds ratio. The relative distances based on the three metrics are defined, and corresponding test procedures are developed. The type I error rates and powers are investigated theoretically and empirically.

Sample size determination for individual bioequivalence inference

Statistical criterion for evaluation of individual bioequivalence (IBE) between generic and innovative products often involves a function of the second moments of normal distributions. Under replicated crossover designs, the aggregate criterion for IBE proposed by the guidance of the U.S. Food and Drug Administration (FDA) contains the squared mean difference, variance of subject-by-formulation interaction, and the difference in within-subject variances between the generic and innovative products. The upper confidence bound for the linearized form of the criterion derived by the modified large sample (MLS) method is proposed in the 2001 U.S. FDA guidance as a testing procedure for evaluation of IBE. Due to the complexity of the power function for the criterion based on the second moments, literature on sample size determination for the inference of IBE is scarce. Under the two-sequence and four-period crossover design, we derive the asymptotic distribution of the upper confidence bound of the linearized criterion. Hence the asymptotic power can be derived for sample size determination for evaluation of IBE. Results of numerical studies are reported. Discussion of sample size determination for evaluation of IBE based on the aggregate criterion of the second moments in practical applications is provided.

Review article: biosimilars are the next generation of drugs for liver and gastrointestinal diseases

BACKGROUND

A biosimilar is a copy version of an approved original biological medicine whose data protection has expired.

AIM

To provide an overview of the development of biosimilars worldwide.

METHODS

Literature review of manufacturing processes of biosimilars, differences and similarities between biosimilars and the reference product, approval pathways for biosimilars, challenges in clinical trial study design and available data from clinical trials.

RESULTS

Biosimilars have the same amino acid sequence and highly similar glycosylation patterns that overlap with the originator product. Both efficacy and toxicity are difficult to predict due to subtle molecular changes that might have profound effects on clinical efficacy, safety and immunogenicity. Their main advantage is related to cost savings. Direct evidence of safety and benefit from clinical trials, post-marketing pharmacoviligance and unequivocal identification of the product as a biosimilar are requirements before approval. Non-inferiority or equivalence trials are required by regulatory agencies. Over the past years, several biosimilars have been approved such as erythropoietin or growth factors. Recently, two monoclonal antibodies, Remsima and Inflectra, have been shown to be equivalent to infliximab (INX) in safety and efficacy in rheumatologic conditions. Interchangeability, automatic substitution and switching are key issues when treating patients with biosimilars in clinical practice.

CONCLUSIONS

Biosimilars represent a new generation of drugs in liver and gastrointestinal diseases. On June 27, 2013, Hospira's Inflectra (INX) was the first biosimilar monoclonal antibody to receive positive opinion from European Medicines Agency's Committee for Medicinal Products for Human Use for rheumatoid arthritis, inflammatory bowel disease and plaque psoriasis.