BIORELIANCE (WWW.BIORELIANCE.COM/US)

Stability testing is required for all biopharmaceutical drug products to detect all changes in identity, purity, and potency as a result of a number of environmental and processing factors. Whether testing is conducted in-house or through contact laboratories, it involves the development and performance of comprehensive and specific stability protocols for all stages of a product’s life cycle (1). Testing product stability in-house requires signficant time and resources, and carries challenges associated with commercialization market, time, and capacity.

Market: The type of stability tests that are conducted depend not only on a product and its intended use and stage of development, but also where that product will be used and stored. Global regions have been divided into five climatic zones (Table 1). Manufacturers must factor in the costs of additional stability tests when deciding on local- and/or global-market product distribution.

Table 1: Climate zones for drug product “room temperature” storage” (RH = relative humidity)

Time: Biologic products have a wide range of shelf lives because degradation pathways and time of degradation depend on the characteristics of a given product. Lyophilized and frozen products can stored for as long as 10 years or more. But the majority of biologics have shelf lives between six months and five years. ICH Q5C recommends that for products with shelf lives ≤1 year, analysts should perform real-time stability studies monthly during the first three months of study and at three-month intervals thereafter. For products with shelf lives ≥1 year, the guideline recommends that stability tests be conducted every three months during the first year of storage and every six months thereafter.

Capacity: Storage areas range from small stability chambers of a few cubic feet to large rooms of several thousand cubic feet. Contract facilities such as Parameter Stability Storage, Whitehouse Labs, and Metrics have significantly increased their stability storage capacities. Other companies are developing temperature-stable storage units, such as BioCision’s Bio T systems.

Capacity issues can put a strain on companies with limited personnel, expertise, and resources. And for some such companies, the decision to outsource some or all stability testing can provide a solution.

Outsourcing Expertise
I spoke with several professionals at contract laboratories about their processes for working with sponsor companies on stability testing. Participating in this “virtual roundtable” are Rekha Patel (global director, large molecules, at Catalent Pharma Solutions), Tim Brown (director of stability at Amgen, formerly at Diosynth), Alison Armstrong, PhD (senior director of development services at BioReliance), Niall Dinwoodie (global coordinator of analytical testing, biologics testing solutions at Charles River), and Ashleigh Wake (biopharmaceutical services leader at Intertek Life Sciences).

The views expressed here are those of the individuals and do not necessarily reflect the views of their employers.

Choosing to Outsource Stability Testing
What are the benefits of outsourcing stability testing services over performing such tests in house?
Dinwoodie: “It’s really about resource management, both in terms of equipment and available staff. Stability studies have time points over long periods. For example, after six months of a standard testing pattern, you could get out to intervals of three or six months and even annual testing. And you need resources to conduct that testing. It is difficult to maintain in house unless you have a lot of stability programs up and running. Contract laboratories get stability programs from a number of clients with different timelines and schedules. So they are able to ‘fit’ different programs together to create an even workload for their staff and laboratories.”

Patel: “Manufacturers may not have some or all of the necessary capabilities, techniques, and expertise in-house, to support stability testing. In most cases, my company has the capability and expertise to support all the testing needed for large-molecule materials such as drug substances, drug products, intermediates, and biosimilars.

“Also, the capacity of the chambers or the appropriate temperature/ humidity conditions needed for stability studies may not be available. So outsourcing storage to a laboratory vendor is feasible. My company, for example, has approximately 76,000 ft³ of stability storage chambers with temperature conditions ranging from –80 °C to +60 °C and humidity conditions ranging from 25% relative humidity (RH) to 90% RH. We can support photostability conditions, freeze–thaw studies, and thermal cyle studies.

“Finally, in-house personnel resources for testing and supporting stability programs may be at capacity. Stability is fairly easy to outsource because it’s relatively routine and requires little oversight from manufacturers.”

Brown: “There are several benefits to contract stability-testing services. For me, they include the ability to allow drug-innovator companies to focus on pursuing completion of clinical trials, marketing and biologics license applications (BLAs), and commercialization without having to maintain long-term stability studies that could span several years. Batch release is closely related to manufacturing processes, whereas stability testing continues years after batches have been manufactured.

“Contracting also allows better cost management for stability testing as well as the ability to quickly respond to changes in a product’s development or commercialization life cycle. Because clinical trials and market demands are subject to change, delinking release and stability testing activities provides greater flexibility. And it’s also a great opportunity for innovator companies to create strategic alliances to support business continuity.”

Wake: “One of the biggest benefits I can see is that outsourcing stability testing to a contract research organization (CRO) opens up a wealth of experiences that go beyond ‘in-house working practices.’ Working in a CRO, we are in an almost privileged position of seeing many different approaches to conducting stability studies and (perhaps more important) the regulatory feedback they produce. With biologics — for which there is less certainty of regulatory expectation and historical data for reference — the fact that we can use learnings from others in design and implementation of studies can add a great deal to an analytical submission.”

Armstrong: “All stability testing performed by contract providers is completed in strict quality-controlled environments, which are continually monitored. Such contract houses have extensive expertise in regulatory expectations. They understand implications for related aspects of stability projects for a wide range of different types of products. Dedicated stability coordinators should ensure that the appropriate materials are prepared for testing when they are needed, and that testing meets and/or exceeds ICH guidelines from start to finish.

“Furthermore, stability storage should be operated under ICH-recommended conditions with continuous maintenance, monitoring, and security in place. Implementation of an ICH-compliant stability program can include a range of storage conditions, including –70 °C, -20 °C, 5 °C, 25 °C with 60% RH, and 40 °C with 75% RH. Multiple lots of drug substances and drug products are analyzed using stability protocols that indicate which assay methods should be used at specific times. The objective of this program is to establish storage conditions and expiration dates.”

Designing Testing Protocols
How do contract laboratories develop stability testing protocols with their clients?
Dinwoodie: “First, we need to know the development state of a product and information about its known stability. Then, with our client, we will design a study that is appropriate to the regulatory stage of that product, whether it’s entering clinical phase 1 trials or phase 3 or it’s commitment studies for ongoing products on the market. We will design a study around that information, including the appropriate number of time points and storage conditions and the range of tests that are involved. We would then draft a protocol and agree to it with the client.”

Patel: “Before initiating a stability program, you should understand the design. That includes temperature and humidity conditions, number of lots, and the materials on hand. The methods will need to have been appropriately developed and validated, including the ability to perform as a stability-indicating method. Additional information that can be useful includes packaging configuration and global filing status. My company can suggest how to combine studies or develop the most efficient and least costly approach to stability programs, such as understanding our clients’ global filing and how to incorporate that to minimize costs and time.

“Contract laboratories such as Catalent offer a comprehensive array of testing to support a variety of small- and large-molecule stability programs. Depending on the type of molecule, phase of development, and type of study, we can provide support from storage, protocol design, and testing. Some clients already have a design in mind for their stability program(s), and we will work with that design. However, for those clients who do not have in-house expertise for designing stability programs, we offer dedicated stability coordinators with large-molecule stability expertise that can provide design assistance. We support stability programs for large molecules for product development from pre-IND to and including commercial phases. Examples of such stability programs include prototype stability, registration, prototype/formulation, clinical studies, engineering studies, in-use studies, shipping studies, temperature-excursion studies, accelerated studies, shelf life, forced degradation, freeze–thaw, photostability, bulk hold stability, extractables and leachables, excipient compatibility, and commercial annual commitment studies.”

Brown: “Innovator companies are fully responsible for the overall management of stability studies. Because of differences in quality systems and procedural controls between the innovators and contract testing organizations, use of stability protocols helps maintain project consistency between the two companies.

“The steps I see are

• Innovator drafts a parent protocol for the product. This outlines the intent of the outsourced study and general study management.
• The contract testing company translates client requirements into an in-house stability protocol template, which allows for details such as procedural references and for staff training using the in-house protocol and associated procedures.
• Contract testing laboratories should reference their parent protocols so that any changes made by innovator or contract testing laboratory will be accounted for using either a document change process (in the case of clinical nonfiled commitments) or formal change control (for studies that are filed or have formal regulatory commitments).

“Having clear roles and responsibilities spelled out through a well-defined quality agreement and contact always helps in the creation of strategic relationships.”

Wake: “In all our programs, whether designing a single stability study or a suite of batch-release tests, we work under a similar philosophy: The most successful studies are obtained when we work in partnership with our clients. In developing a protocol, we would instigate a kick-off meeting to discuss relevant information. We ask questions such as ‘What if anything has been done previously?’ ‘What methods are or are not in place?’ ‘Is the potential degradation route understood?’ Based on the answers, we know where the start point is. For example, we need to do a forced degradation study to facilitate development of stability indicating methods.

“Once that information is understood, we put together a stability program based on our standard design (ICH stability) and hold discussions with the sponsor company to discuss specific needs or peculiarities.”

Armstrong: “Our stability protocols are developed and prepared with the sponsor. Both parties sign the protocol. The protocol serves to guide stability studies. A prepared stability protocol contains information describing the product to be tested, its sampling process, study duration, number of samples required and replicates per time interval, storage conditions, and methods of analysis.

“A stability study also includes evaluation of both drug substance and drug product. It provides sufficient data to indicate that a product retains its specification within established limits throughout its shelf life. The chosen profile ensures that changes in product identity, purity, and/or potency will be detected through stability data. The data also should reflect the length of a clinical trial and should run alongside that trial.

“A documented stability program using relevant analytical test procedures should be used to monitor the integrity of a drug substance and to detect changes to it during storage. Acceptable limits of degradation are determined from analytical profiles of drug substances and drug product lots used in preclinical and clinical studies. Testing should cover attributes susceptible to change during storage and  that are likely to influence quality, safety, and/or efficacy. Biological products usually require precise storage temperatures because such products are particularly sensitive to temperature changes. Factors such as humidity, light exposure, product container–closure interactions, and accelerated and stress conditions must be considered when developing a stability program.

“Stability assay methods should be specific enough to differentiate between analytes and possible degradation products. The overall quality of drug-substance and drug-product batches placed on formal stability studies should represent the quality of materials used in clinical studies and of the quality of materials to be made at manufacturing scale. Supporting stability data can be provided using stability data generated from batches of drug substances and drug products made on a laboratory scale. Stability studies also should be conducted on material stored in a container–closure system that is the same as (or simulates) packaging proposed for real storage and distribution.”

Analytical Methods
Are specific analytical methods and bioassays routinely relied upon for particular drug-product types?
Dinwoodie: “Some methods would almost always be applied because of the product type, such as looking at subvisible particulates in any liquid formulation. For many products you also might use osmolality tests in place of testing all excipients, because it’s a much simpler test. Otherwise, it’s really the standard battery of tests that you would apply to a molecule for quality control purposes, which includes high-performance liquid chromatography methods, electrophoresis methods, and anything that will separate impurities that may be formed during storage. Other standard tests include potency assays that confirm that the molecule is still active.”

Patel: “The range of testing is diverse, from simple compendial methods such as appearance, pH, and particle analysis to more complex methods such as bioassays. The battery of tests needed for stability programs largely depends on a given molecule (type, manufacturing, and so on), regulatory filing, and purpose of the study or program.

“You can usually identify which assays are needed for stability, but you have to produce the data to confirm that those methods are stability indicating. That would be part of your phase-specific validations. Some formulation and experimental stability studies can be performed without complete validations, but for most other studies needed for regulatory filings, a phase-appropriate validation must be conducted.”

Brown: “Analytical methods are a bit tricky. Obviously, the closer you get to a product’s capability or potency, the more interest you get from regulatory authorities. Most protein-based drugs have similar degradation pathways. However, their importance is usually determined through a drug development cycle and relates back to clinical experience and efficacy.”

Wake: “As part of a stability program, we will always evaluate ‘core characteristics’ — for example, sterility, total protein assay, and appearance. Such assessments generally use standard or even pharmacopeial monograph methods that are appropriate to the type of material. Other criteria are still general (e.g, a bioassay to establish potency). But the methodology used will differ and be product specific. End points and analyses are also very specific to a given molecule. For example, if forced-degradation studies indicate that oxidation increases on storage, then specific assays would be needed to explore that.”

Armstrong: “A series of pharmacopeial methodologies are assessed to ensure that a product does not affect overall sensitivity and specificity of the test results. In addition, product-specific methods (e.g., purity, identity, and potency parameters) will have been developed and validated for use with relevant products. Product-specific qualifications are performed for all assays to ensure consistency in quality and scientific relevance for those methods.”

Working on “Next-Generation” Biologics
How do you approach some “newer” biologics, such as ADCs, biosimilars, combination products, and cell and gene therapies?
Dinwoodie: “We work on a variety of drug products. The type of stability tests is dictated by product type, the only difference is that you are determining an approach for the tests that you apply, the storage conditions that you can use, and the duration of a stability study. You design a study differently and have testing at wider intervals if you’re looking at a finished drug product in a lyophilized vial, for example (which might be stable for two or three years) rather than a cell therapy product that may have to be generated rapidly in a hospital environment and quickly returned to a patient. So you need to focus on different frequencies of testing and testing regimes based on product type.”

Patel: “An ADC product, for example, may need an additional assay such as free drug or drug–antibody ratio (DAR), which would not be appropriate for a MAb product.”

Brown: “Each of those ‘next-generation’ therapies are changing the landscape of stability study designs. Many original study strategies still apply (e.g., temperature and storage conditions). However, just like when the biotechnology products came into scope, new guidance documents had to be drafted to address some of the nuances.

“Entire books can be written on the combination products front, given that one size will not fit all. Consideration has to be given to what constitutes the date of manufacture when combining device and drug entity along with considerations of humidity when, historically, liquid vials and syringes where not required to be studied under such conditions.

“Companies still struggle with when to apply accelerated conditions to predict real-time storage for cases in which you have a drug that can use Arrhenius equations and large molecules that require real-time and real-temperature studies to establish expiry dates.”

Wake: “The overall process for stability assessment does not differ in principle from product to product; that is, the process involves elucidation of potential degradation routes used as a basis to develop a series of stability-indicating methods, validation of these methods, and design of studies. That process includes long-term and accelerated testing at appropriate conditions and (if applicable) sample presentations and orientations.

“What might change are the types of tests included, storage conditions, and storage times. Biosimilar programs might be an exception. Such tests can (although not always, and stability is a must for submission) at certain phases be comparison based.”

Armstrong: “The ICH Q5C harmonized tripartite guideline on the quality of biotechnology products (stability testing of biotechnological/ biological products) states the following:

The shelf life of a biotechnological product may vary from days to several years. With only a few exceptions, however, the shelf life will be within 0.5 to 5 years. When shelf lives of one year or less are proposed, the real-time stability studies should be conducted monthly for the first three months and at three-month intervals thereafter. For products with proposed shelf lives of greater than 1 year, the studies should be conducted every three months during the first year of storage, every six months during the second year, and annually thereafter.

“Forced-degradation studies and/or stress testing help determine the intrinsic stability of a molecule by establishing degradation pathways to identify likely degradation products and to validate stability-indicating power of analytical procedures used. Stress testing is conducted to provide data on forced decomposition products and decomposition mechanisms. tress testing will cover most severe conditions that may be encountered during distribution.

“Overall, those studies should establish the inherent stability characteristics of a molecule (such as degradation pathways) and lead to identification of degradation products. So the tests support the suitability of proposed analytical procedures. Their detailed nature depends on individual drug substances and type of drug product. Stress testing should include the effect of temperatures in 10 °C increments above the accelerated temperature test condition (e.g., 50 °C, 60 °C, and so on), humidity if appropriate (e.g., ≥75% RH), oxidation, photolysis, susceptibility to hydrolysis across a wide range of pH values in solution or suspension, and freeze–thaw assessment. Photostability testing also should be an integral part of stress testing. The ICH Q1B guideline defines standard conditions for photostability testing.”

Technology Transfer
What steps should contract laboratories and innovator companies take to prevent technology transfer problems with stability testing?
Dinwoodie: “The most important thing is to have face-to-face contact with analysts from the originating laboratory who are familiar with the assays. Also it is important for supervisors from the receiving laboratory who will be reviewing data to be actively involved in the transfer. Finally, it is important to look at past validation points and past data to understand the issues that might arise to make troubleshooting easier, because invariably there will be some issues.

“In addition, contract laboratory staff should look at data generated within the originating laboratory. That information will allow the contract staff to set comparability criteria for the acceptance of the transfer. You need to make sure that the right data sets are picked and the right variables are being looked at when you are trying to compare the assay between the originating laboratory and the transfer laboratory.”

Brown:  “Technology transfer all comes down to having good scientific understanding of the technology and clear ownership of the transfer from the donor laboratory or site. Well-written protocols that include agreement by both donor and recipient sites are key to success. It is also good to have some cross training between the two sites, so that any ambiguities can be addressed, which will help eliminate multiple hand-offs and rework between the two sites.”

Wake: “We use a host of different safeguards because tech transfer can be an issue of some significance.First, we will always endeavor to match kit (e.g., make of chromatography equipment), because we have seen reproducibility issues when moving between different makes and models. For assays relying on critical commercial reagents, we perform intermediate precision experiments, looking at different batches, as part of a validation. We also often extend that to look at the transfer laboratories’ potential suppliers. We also ensure that for complex methods, transfer always involves one of our staff traveling to the transfer laboratory or vice versa. That ensures that nothing is lost in the translation of a method.”

Armstrong: “Before any agreement relating to technology transfer, the methodology under consideration should be appropriately documented. This will include development reports, validation reports, and standard operating procedures. Such documents should be available to the receiving laboratory for review and understanding. And appropriate training for a given method is recommended either at the originating site or at the receiving site.

“The formal transfer program will be fully documented and approved by both the receiving and originating sites. The transfer will include assessment of qualified materials from the originating site and materials that have been purchased from approved vendors for use at the receiving site. The transfer should be performed with materials that have been tested (e.g., controls or blinded samples) and have predefined acceptance criteria.”

Final Thoughts
Brown: “Other hot topics in stability include the fact that not all regions accept ICH stability terminology and approaches. Also, there is a shift toward stability studies that support transportation and temperature excursion in emerging markets. I feel that the contract stability side of the industry will need to move away from the classical stability arena. Testing laboratories will need to embrace some of these more unique stability strategies if they are going to be able to meet the needs facing the innovator companies. Much of this knowledge is gained by the innovator companies’ continual engagement with regulatory authorities throughout a product’s life cycle.”

Dinwoodie: “People tend to think of stability studies being long term, but still only think of them as being the duration of the single batch expiry, about two to three years. But in fact, programs start at the phase 1 level and go on to supporting the product through phase 3 and then onto the market. So we have a number of products that we have been performing stability tests on for 12 or 15 years since we first started testing the product. New batches of the product are under testing, but there are still batches going through storage. It’s an ongoing commitment, not just a short-term test. So it is important that if you are thinking about contracting out these studies, you are aware of the long-term reliability of the organization you are working with.”

Reference
1 Rios M. Product Stability Testing: Developiong Methods for New Biologics and Emerging Markets. BioProcess Int. 13(5) 2015.

Maribel Rios is managing editor of BioProcess International, mrios@ bioprocessintl.com