Fortunately, there are several organisations and working groups across industry that are working together to address this challenge.
A one-day workshop hosted by The US Department of Commerce’s National Institute of Standards and Technology (NIST) in late April 2023 brought together participants from across industry to focus on collaborative efforts to enable the adoption of rapid microbial testing methods for advanced therapy products.3
The session opened with a presentation4 from Veera Dheenadhayalan, Director of Biosafety at AstraZeneca, who discussed the implementation of a rapid microbial test method in the quality control (QC) microbiology lab at AstraZeneca.
He outlined the different categories of microbial detection methods; these include culture-based methods, which are based on changes in type of metabolic activities and culture-free detection systems, which are based on the presence of DNA proteins or antigenic targets.
Dheenadhayalan then explored the key factors to consider when selecting the ideal microbial testing method for programmes – specifically for cell and gene therapies.
Turnaround time is “critical” for cell and gene therapy programmes, Dheenadhayalan told the audience, noting that sensitivity, efficiency of detection of microbial species (both bacteria and fungi), in-house capabilities, lab space, implementation timeline, robustness, ease of interpretation and regulatory acceptance are all factors to consider when selecting an RMM.4
According to US Food and Drug Administration (FDA) guidance: Chemistry, Manufacturing, and Control Information for Human Gene Therapy Investigational New Drug Applications (INDs),5 there are provisions for analytical procedures that differ from USP <71>, the compendial method, which can be accepted if there is adequate information on specificity, sensitivity and robustness. There are also specific examples of rapid methods for sterility or mycoplasma testing based on polymerase chain reaction (PCR) results that are acceptable if the method is qualified/validated to ensure it is fit for intended use.5
Similarly in Europe, 2018 guidelines on Good Manufacturing Practice specific to Advanced Therapy Medicinal Products6 include provisions that can accommodate the introduction of alternative testing method for microbial detections.
The guidance states: “The application of the sterility test to the finished product in accordance with the European Pharmacopoeia (Ph. Eur. 2.6.1) may not always be possible due to the scarcity of materials available, or it may not be possible to wait for the final result of the test before the product is released due to short shelf-life or medical need.”6
the use of alternative rapid microbiological methods “may be acceptable…provided that the suitability of the method for the specific product has been demonstrated”
Again, the use of alternative rapid microbiological methods “may be acceptable…provided that the suitability of the method for the specific product has been demonstrated.
Dheenadhayalan also shared details of one method chosen by AstraZeneca – a nucleic acid-based method using quantitative polymerase chain reaction (qPCR) for rapid microbial detection.4
He outlined a five-step approach taken to implement the method, which included:
- a system and sample matrix suitability assessment;
- pre-qualification data generation;
- qualification with sensitivity, specificity and ruggedness evaluations; development of investigation strategies;
and finally, validation for commercial cases.4
Additionally, Dheenadhayalan highlighted several other projects at AstraZeneca, including the use of next-generation sequencing (NGS) for adventitious virus detection, as well as the development of nucleic acid-based methods for quantifying retroviruses to replace transmission electron microscopy.4
Collaborative efforts on rapid methods
The NIST workshop3 also included presentations by representatives from US Pharmacopeia, the Parenteral Drug Association (PDA) and National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL).
RMM are “one of the top priority areas” for USP’s new Microbiology Expert Committee, according to Huiping Tu, PhD, Senior Principal Scientist at US Pharmacopeia.
She explained priorities include developing USP <75>, focused on nucleic amplification methods, as well as USP <76> on flow cytometry-based methods. “We’re also considering work to provide the alternative method for the general chapter USP <60>, tests for Burkholderia cepacia complex (BCC),” Tu said.
More broadly, the voluntary committee at USP is committed to exploring new technologies as alternative rapid methods for determining contamination and identifying microorganisms, along with looking to expand their applicability to non-short-shelf-life sterile and non-sterile products.
the [updated] PDA Technical Report No. 33 [is anticipated for] release in the first quarter of 2024″
Participants also heard from Fred Ayers about how the PDA is working on an update of PDA Technical Report No. 33, Evaluation, Validation and Implementation of Alternative and Rapid Microbiological Methods, for anticipated release in the first quarter of 2024.
Jennifer Mantle, Regulatory Committee Coordinator/Technical Project Manager at NIIMBL, also gave an overview of seven community-led projects the public-private partnership is involved with in rapid microbial detection. Projects include an evaluation of NGS as a rapid, alternative assay for in vivo and in vitro adventitious virus testing for vaccine safety,7 as well as a project exploring the use of automated imaging for rapid bioburden or sterility testing.
Another cross-industry group, the Modern Microbial Methods Collaboration or M3 Collaboration, brings together participants from across industry with the goal of modernising pharmaceutical microbiology.
Established in 2021, M3 Collaboration consists of a steering committee and three sub-teams, which focus on specific topics such as biofluorescent particle counting, understanding baseline counts and setting alert levels, and developing communication tools for modern methods.
“Adoption of new technologies has always been a challenge in this industry,” explained Allison Scott, M3 Collaboration Steering Committee and Sub-Team #3 Facilitator, in a recent EPR podcast.8
She added: “As modern methods can take a lot of time and be expensive to adopt, seeing other companies succeed can be ‘very beneficial’ – they can share their success, they can share the challenges that they’ve overcome, and this really helps lead the industry forward.”
Progress implementing rapid methods: ATP bioluminescence
Reflecting on progress implementing rapid microbial methods in 2022, Miriam Guest, Principal Microbiologist at AstraZeneca, highlighted achievements in the use of adenosine triphosphate (ATP) bioluminescence for rapid sterility.9
“Not only are we using ATP bioluminescence for rapid sterility on our new and legacy products, we are also applying it in suspect positive media fill or sterility test units where we have a product that renders the media turbid and we need an unequivocal result,” Guest stated.
She recalled one instance, on technical material, where there was a need to meet tight timelines. “While the material was not made under true aseptic conditions, nor manufactured for human use, we were confident it would meet the sterility requirement we needed for the subsequent testing.
“We took the step to execute a sterility test via ATP bioluminescence (we did a quick sample screen prior to ensure it did not interfere) and despite the broth looking absolutely crystal clear, we got a positive hit on the ATP.
“We executed our standard subculture steps and did a broth extract, where we executed a MALDI-TOF prior to the observation of visible growth on the subculture agar plates. This early information on the ID enabled us to ensure our subculture step was suitable to recover the likely organism.
“In this circumstance, it really highlighted the benefits of adopting new technology in the microbiology lab and supported project timelines. We simply would not have been able to achieve this if we only had traditional techniques available,” Guest concluded.
References
1. American Society of Gene & Cell Therapy – Clinical Trials Finder [Internet]. [cited 2023 Jun]. Available from: https://asgct.careboxhealth.com/.
2. Cell and gene therapy global market report 2023 – Research and Markets [Internet]. [cited 2023 Jun 13]. Available from: https://www.researchandmarkets.com/reports/5733866/cell-gene-therapy-global-market-report.
3. Hosted Workshop on collaborative efforts to enable adoption of rapid microbial testing methods for advanced therapy products [Internet]. 2023 [cited 2023 Jun]. Available from: https://www.nist.gov/news-events/events/2023/04/nist-hosted-workshop-collaborative-efforts-enable-adoption-rapid.
4. Dheenadhayalan V. 2023. Keynote Presentation: A Pathway for Implementing Rapid Microbial Test Method. Hosted Workshop on collaborative efforts to enable adoption of rapid microbial testing methods for advanced therapy products.
5. CMC information for human gene therapy INDs [Internet]. US FDA; 2020 [cited 2023 Jun]. Available from: https://www.fda.gov/media/113760/download.
6. The Rules Governing Medicinal Products in the European Union Volume 4 Good Manufacturing Practice Guidelines on Good Manufacturing Practice specific to Advanced Therapy Medicinal Products 2018 [cited 2023 Jun].
7. Evaluation of next generation sequencing (NGS) as a rapid, alternative assay for in vivo and in vitro adventitious virus testing for vaccine safety [Internet]. [cited 2023 Jun]. Available from: https://niimbl.my.site.com/s/pc31-305.
8. Collaboration in microbiology – EPR podcast 19 – M3 Collaboration [Internet]. [cited 2023 Jun]. Available from: https://www.europeanpharmaceuticalreview.com/podcasts/epr-podcast-19-collaboration-in-microbiology-allison-scott-lynn-johnson-and-miriam-guest-m%c2%b3-collaboration/.
9. Eckford C. 2023. Pharmaceutical microbiology: key developments 2022. [Internet]. [cited 2023 Jun] Available from: https://www.europeanpharmaceuticalreview.com/article/178422/pharmaceutical-microbiology-key-developments-2022/.
