European Bioanalysis Forum Continued Plans to Support Liquid Microsampling

Keywords::

• consortium
• EBF
• experiments
• liquid microsampling
• validation

Since early 2008, the European Bioanalysis Forum (EBF) has been actively engaged in the discussion regarding the use of dried blood spot (DBS) sampling and has gradually increased their involvement by providing science-based input to the developing dialog within industry on the subject. Our contribution was built on the experience of many experts in our community who came together with the aim of providing an answer to, or a broader perspective on, the bioanalytical challenges of DBS. The commitment of the EBF community to supporting the development of DBS was illustrated by the formation of an EBF DBS Consortium, in which we shared bioanalytical experience and agreed to perform focused DBS experiments. Furthermore, the Consortium connected different stakeholders in bioanalysis as well as in other expertise areas impacted by this technology, such as pharmacokinetics (PK) and toxicokinetics (TK) [1]. The results of the discussions and experiments performed by the Consortium were shared with industry at conferences, workshops and via publications [2–6]. This has added to the many individual contributions from the broader scientific peer community [7–9] and other industry consortia. In addition, in order to share our thoughts on a more effective strategy for the development and acceptance of the technology in those areas where it can provide immediate added value, we tried to provide context to the real or perceived hurdles for DBS and shared our vision on how this technology would fit into a wider implementation of microsampling [10,11]. One element of this vision was to ensure that the hurdles of DBS would not be inadvertently generalized and applied to other areas of microsampling. To emphasize the latter, one of our recommendations was to highlight DBS as ‘one of the approaches’ for microsampling, rather than ‘the approach’. Consequently, the EBF-DBS Consortium was rebranded to reflect this commitment and continued as the ‘EBF DBS-Microsampling Consortium’. After the recent publication of our updated recommendations [3], we refocused our efforts away from DBS sampling, although the Consortium offered to continue as a pivot point if needed, and regrouped around the opportunities for liquid microsampling (LMS) approaches. To reflect this, the name of the Consortium was rebranded to the current EBF Liquid Microsampling Consortium (EBF LMS Consortium).

Building the EBF LMS Consortium

Similarly to the initial formation of the DBS Consortium, we reached out to our members and invited them to join this new LMS Consortium. Thirteen companies with hands-on experience and vested interest in LMS signed up and declared that they were prepared to share nonproprietary data on LMS experiments and/or be available to perform bioanalytical experiments focused on LMS designed and agreed upon by the team. The team came together for the first time in a workshop on 23 October 2013 in Brussels, Belgium. The interactive discussion yielded a shortlist of the potential challenges related to LMS, in addition to some initial ideas on experiments that would be needed to further investigate some of these scientific or regulatory challenges. In addition, the team discussed subjects such as how to stimulate the acceptance of LMS in a regulatory setting versus discovery, how to integrate the ‘tiered approach’ to bioanalytical method qualification/validation and how to identify potential blockers/concerns for wider adoption/acceptance of the various available techniques.

The Brussels workshop immediately identified a couple of very practical advantages of LMS over the DBS approach, primarily because we can use the same practices that are employed for larger liquid samples (i.e., pipette a second aliquot). Hence, the challenges in LMS are not very different from traditional bioanalysis practices. One example is the potential for re-assay using the same sample. Similarly, sample dilutions will become more practical compared with DBS.

In addition to the workshop, a brief survey was issued to all EBF members in order to probe more widely for ideas regarding the experiments the team is designing. Mirroring our initial DBS survey [2], we again limited this survey to two very simple questions:

• When validating an assay for the analysis of samples taken using LMS techniques, what experiments (if any) do you add to the method validation?

• When validating an assay for the analysis of samples taken using LMS techniques, what experiments (if any) do you exclude from the method validation?

The outcome of the survey, in which 20 companies participated, aligned well with the ideas that were already generated by the Consortium team members during the October workshop, and as such, added more weight to the selection and design of the key experiments we plan to perform.

Summarizing the input from the workshop and the survey, and prior to diving into the designing of experiments in the following weeks, it may be appropriate to look at the challenges from a greater distance and categorize the different challenges in a more orthogonal way. Most of the identified challenges may fall into three areas:

• The first area is composed of challenges that are very similar to those for DBS and are not solely related to the activities of the bioanalyst (e.g., considerations on the sampling site [capillary blood vs venous blood] or the choice of analyzing blood or plasma as the primary matrix for PK and TK). We consider that these challenges should be part of a peer discussion with all stakeholders in PK, pharmacodynamics or TK, which at some point must also include the regulators. We consider that a lot of the data on these challenges are likely to already be available in many companies, and so our role is to stimulate the industry to make these data available as part of other consortia, such as the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), or similar [12].

• The second area involves some challenges identified for LMS that may appear to be identical to DBS, but either have a different origin or an alternative solution. ‘Homogeneity’ is a good example for this: in the context of DBS, homogeneity was strongly related to filter paper properties, the physicochemical properties of the drug and/or hematocrit. In the case of LMS, homogeneity may be more influenced by the sample and subaliquot volumes or the characteristics of the container used to produce and/or store the sample (e.g., the relationship between sample homogeneity and the dimensions of the capillary used for sampling).

• The third area can be classified as ‘unique to LMS’. In this context, ‘unique to LMS’ also raised the question: “When should we, or even should we at all, start identifying a sample as a ‘microsample’?” The appreciation may be different from a bioanalytical perspective compared with a preclinical or clinical setting, with the latter two driven by ethical considerations rather than from analytical challenges (e.g., the [in]ability to harvest plasma from a liquid blood sample that, in LMS, is driven by the sample volume and capillary/container). In this context, the adsorption of drugs into capillaries or other containers because of the less favorable volume-to-container surface ratio for LMS is an area for consideration, especially in the case of low concentrations of basic or lipophilic drugs.

Next steps

The EBF LMS Consortium plans to look at the data already available within the industry and, from this, will define experiments using a portfolio of nonproprietary compounds in order to provide robust data to fully understand and support the use of the LMS.

All of our experiments will be built on following principles:

• Practice unbiased science: experiments will be designed to provide answers to specific questions related to LMS.

• Allow a pragmatic approach: the knowledge that a liquid microsample is, in essence, no different from a traditional liquid sample is an important starting point. For this, it may be advantageous to obtain industry agreement as to the maximum sample volume that can be used to define a sample as a microsample. From a bioanalytical perspective, this may be the stage at which we encounter an analytical challenge that is derived solely from the sample size, either driven by the technique or compound properties. It is likely that beyond the bioanalytical space, the appreciation of what is perceived as a microsample will probably be different in a clinical (likely to be mostly ethical or patient comfort considerations) or a preclinical/TK (mostly 3R considerations) context. Good communication is needed in order to prevent the bioanalytical community from going into overdrive on what these stakeholders may refer to as a microsample, but that, in essence, is a simple liquid sample from a bioanalytical perspective.

• Use past experience: include learning points from DBS and identify the areas in drug development where LMS may add unequivocal, unbiased and immediate value (scientific, ethical and logistic/financial) and capitalize on this value, instead of proposing a general switch to LMS. In learning from the past, it is probably also the right time to integrate this new thinking in order to give more consideration to a tiered approach or assay/stage-appropriate scientific validation [13], and not routinely push the use of LMS into the realms of regulated bioanalysis standards if this is not called for.

Finally, the team does not have the intention of suggesting that there is a difference between a liquid microsample and a traditional liquid sample, if there is no scientific evidence to make this distinction. This will make the acceptance by industry and regulators of LMS easier. LMS may in fact be nothing other than a next level of ‘a smaller sample’, facilitating the 3Rs [12] or clinical studies, where sample volume is currently a limiting factor with respect to patient comfort and ethics.

Future perspective

Now the team has a good idea of the challenges and gaps in our understanding for LMS, they can fine tune and translate them into concrete bioanalytical experiments. Going forwards, we will continue to reach out and communicate more details on these planned experiments and provide context on how they fit into the proposed strategy for successful LMS, either via rapid communications or a Focus Workshop. We hope to be able to report back on the results of the first battery of experiments at the 7th Annual Open Symposium (Barcelona, Spain, 21–23 November 2014). We will continue to strengthen our relationships with other consortia or industry initiatives in order to ensure appropriate cross-fertilization and data sharing. High on our list of priorities are the stakeholders who are the recipients of the bioanalytical data, such as the NC3R Microsampling Working Group.

Disclaimer

The views and conclusion presented in this paper are those of the European Bioanalysis Forum and do not necessarily reflect the representative affiliations’ or companys’ positions on the subject.

Acknowledgements

The authors wish to thank the member companies of the EBF LMS Consortium (AstraZeneca, Charles River Laboratories, Covance, GlaxoSmithKline, Janssen Research & Development Novartis, LGC, Lundbeck, PRA, Sanofi, Shire, TNO Triskelion and QPS) for their contribution to the workshop and review of the manuscript and all EBF members for their input in the surveys.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.