EBF and Dried Blood Spots: From Recommendations to Potential Resolution

Keywords::

• bioanalysis
• blood analysis
• dried blood spots
• DBS
• EBF
• European Bioanalysis Forum

With more and more companies getting involved in analyzing dried blood spot (DBS) samples for regulated bioanalysis, the pharmaceutical industry’s perspective on the potential and the hurdles of this technology is continuously broadening. As data on a broader chemical space is published, in addition to the initial advantages, the potential hurdles or roadblocks are becoming more apparent. At the same time, there may be a risk of the scientific community focusing on the details of the technology too much and not reflecting on the higher goals of using DBS occasionally.

From early on, the European Bioanalysis Forum (EBF) joined the DBS discussions through internal surveys and discussions, and the organization of a Focus Meeting on the technology [101]. The EBF presented their initial recommendations on the validation of the DBS assays at international meetings [1], after which it was published as a White Paper [2]. This recommendation was not seen as an end point by the EBF in their efforts to further support the development of the technology. At the last EBF annual Strategy Meeting in Limelette, Belgium in March 2011, the EBF member companies agreed to continue to connect scientists and experts on DBS. In essence, two major initiatives were agreed at that meeting:

• The formation of an internal DBS topic team (TT) within the EBF to develop initiatives and look at strategies on DBS

• The organization of a regional workshop on DBS to bring together EBF and non-EBF companies in what could become an industry consortium on DBS.

The TT was formed by representatives from seven EBF member companies, being the current authors of this editorial. TT members are currently all from the pharmaceutical industry. However, with the EBF broadening to also include CROs as members, the TT would certainly welcome input from the CROs. For 2011, the TT has taken on board the responsibility to prepare and host the external activities organized by the EBF on DBS in a broad sense, such as the organization of a workshop and building the DBS session at the EBF Open Symposium in Barcelona in November 2011. In addition, the TT has looked into a refocusing and broadening of the DBS discussion, as explained later in this article. Lastly, the TT will prepare presentations and publications on the outcome of the multiple scientific and process discussions on DBS held within the broadening group of EBF member companies.

A first tangible outcome of the TT discussion is that the EBF proposes to refocus the DBS discussion at two levels or tiers. In this, the EBF is not proposing anything new. But with the discussions on the potential (real or perceived) scientific hurdles on the technology taking a too prominent role in the last 2 years, and as such dominating the discussions between industry and the regulatory authorities, the EBF feels it is a good moment in time to remind the global scientific community on the reasons why DBS is being used in regulated bioanalysis, or more generally, in support of pharmacokinetic (PK) studies. Hence, the EBF proposes to initiate a higher level of discussion, highlighting the drivers the industry identified to include DBS into the drug development process. This will allow us to rethink or re-evaluate if DBS is the best choice to accomplish those individual goals. With DBS being strongly connected to the sampling of small volumes (3Rs – refinement, reduction or removal of laboratory animals used for preclinical testing – and providing a more patient-friendly technique to sample blood in clinical studies – e.g., applications in neonate studies), some investigators may have lost the perspective that small volumes can also be obtained through other and more conventional means than DBS, and that alternative approaches may be more appropriate. With that, we feel it is important to refocus the discussion on these higher goals and understand the real value of applying DBS in drug development.

A first important consequence of the use of DBS is to have a good knowledge and understanding of the use of blood PK versus plasma PK in PK, pharmacodynamic (PD) or toxicokinetic (TK) studies, and subsequently (and as needed) of the interchangeability of the blood and plasma PK, PK/PD or TK relationships throughout the development of a drug. Second, this recreation of the awareness that sampling of small volumes can also be achieved through other means than spotting blood on a card can help to remove some pressure on those applications where it will be potentially difficult to find a way out of the scientific issues of applying DBS. By using the opportunities provided by sampling liquid blood or small volumes of plasma/serum, we could help focusing the efforts on making DBS a success in those areas where the science and drug development is best served with DBS. In essence, DBS technology may not be beneficial or even applicable in all areas of drug development, but it certainly has its place in a significant number of applications. By understanding the limitations of DBS technology and refocusing the application of DBS to those areas where it can and even should be used, and away from areas where it has limited value, DBS may find a faster way into real and important contributions to the drug-development process. Today, the EBF is not making any formal recommendations on the latter, but it is common knowledge that DBS may potentially have its greatest contribution in late-phase clinical trials, that is, in facilitating trials in developing countries and special patient population, in therapeutic drug monitoring or in sample shipment. At the same time, the need for smaller sample volumes throughout preclinical and clinical development may be achievable through other means than DBS. By providing this continued higher perspective on the reasons why we are optimizing DBS, the industry may be able to focus their efforts on the areas of most added value.

The above reflections were part of the discussions at an EBF DBS workshop organized in Brussels on 23 June 2011. Next to finding a broader agreement on the above strategic vision, the EBF wanted to bring together a broad group of experts in DBS to discuss a number of areas identified as real or perceived hurdles in the broad application and scientific acceptance of DBS. The following companies contributed to the discussion: Abbott, Actelion, Astellas, AstraZeneca, Celerion, Covance, Charles River, Ferring, Ferrer, GlaxoSmithKline, Harlan Laboratories, ICON, Janssen R & D, Lundbeck, Novartis, Nuvisan, Pfizer, QPS, Quotient, Roche, Sanofi-Aventis, Swiss BioQuant, TNO and UCB Pharma.

The EBF recommendation paper served as a starting point [2]. In summary, the EBF identified a broad array of attention points in that paper: inter-/intra-card variability, hematocrit, venous versus capillary blood sampling, anticoagulant, sample homogeneity and spot homogeneity, preparation of QCs/calibration standards, internal standard addition, extraction recovery, sample dilution procedures, spotting technique and volume, punched spot size, sample stability and storage of cards (pre- and post-spotting). It was clear that focusing on all above at the same time was not feasible in a short timeframe. For this workshop, the participants agreed to focus their discussion on hematocrit, internal standard addition, sample dilution procedures and sample stability.

The workshop accomplished its goals. All delegates subscribed to the proposed tiered approach of the DBS discussion, with tier 1 being a strategic discussion on the need of DBS in support of, for example, blood PK or small-volume sampling. As emphasized above, some of these goals can be more easily achieved through other means as DBS. Also, it will be important to engage discussions outside of the bioanalytical community to further develop best practices in industry on this important strategic question. In tier 2, the EBF community agreed to further support the scientific discussion on trying to understand and remove the hurdles currently observed in the bioanalytical method validation of DBS assays and the application thereof. For this, the delegates not only engaged themselves to share historic data and get a broader view on these data, but also agreed to jointly design new experiments that can then be executed across the combined laboratory facilities of the participating companies. Experimental data can then be brought together and discussed or interpreted within the community of participating companies. In practice, four subteams have been formed, each of which are composed of five to seven companies initially (others companies may be added), with each subteam taking one of the four identified topics further. The teams will report back to the EBF TT to ensure maximal connections and progress, and have expressed the desire to reconnect in a follow-up workshop in 6 months.

In the next couple of months, these four groups will bring data together, design and execute experiments of identified areas of gaps, discuss and interpret, and finally share the outcome and conclusions at international meetings or through peer-reviewed publications.

With DBS not being a regional topic, the EBF Steering Committee TT leaders will reach out to other global initiatives in order to prevent undue duplication and maximize synergies.

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.