COVID-19 and patient-centric sampling: panel discussion Q&A follow-up

Patient-centric sampling technologies enable the collection of samples that can be used for the quantitative measurement of molecules relevant for drug development and healthcare in locations which are more convenient to the patient than current approaches. This new type of workflow places patients at the center, enabling previously difficult data to be collected in a more convenient fashion, decreasing the impact on the patient, reducing cost and increases the quality of the data collected.

As countries around the world continue to deal with the COVID-19 pandemic, a panel of experts discussed the impact the pandemic could have on blood sample collection, how a patient-centric sampling approach could help mitigate these challenges and how the approach could become part of the new norm.

Learn more about the Patient Centric Sampling Interest Group>>

Following the discussion, the expert panelist took the floor in a comprehensive Q&A session. Read their answers to some of your questions below.

QFollowing up on Erwin’s statement, what is the progress on using smaller samples for routine clinical tests including clinical chemistry, liver enzymes, CBC?

Erwin Berthier: Most clinical analyzers require very small volumes of sample, the limiting factor is the dead volume – sample that is wasted and never used. There are strategies that can be done to reduce the dead volume of samples using better sample cups or tuning the analyzer process.

QAre there any chain of custody issues with home sampling and how do regulatory agencies view that aspect of the approach?

Melanie Anderson: We’ve had a few exploratory trials that incorporated DNA fingerprinting to confirm patient identity. This approach worked well. In larger trials, DNA fingerprinting can inform on sample discrepancy issues, but is prohibitively expensive to implement for every at home collection. In all likelihood, this concern will be resolved with technology that can remotely confirm patient identity prior to collection (facial or voice recognition capability). The reality is that most of the clinical trial is unobserved and we’re relying on participant compliance for dose adherence, too.

QCan you comment on the use and abuse of FDA emergency use authorization – both the tests but also the ‘self-collection’ component?

Erwin Berthier: In terms of home-use, the FDA has been very careful from onset and few home uses have been granted to date. As the FDA is establishing robust guidelines in this area we should see more come out.

QCollecting blood at home is OK. However, how can serum and plasma be isolated at home? is there any other approach?

Neil Spooner: There are commercially available technologies that use lateral flow to separate the blood components to give a dried plasma like sample. I am not aware of any currently commercial technologies that are able to separate blood to give a liquid serum, or plasma sample. One important consideration with performing these plasma / serum separations using a non-standard centrifugal approach is that whilst the removal of the red blood cell component may give a product that appears similar to that produced traditionally by centrifugation, the effect on the separation of other components of the blood sample is not known. It is therefore possible that the measured concentrations of analytes in these non-standard serum and plasma samples could differ from historical data for that analyte. It may therefore be necessary to perform studies to show concordance between the sample types. One example might be the effect of the separation on the measured concentration of large molecule protein drugs. Another might be small molecule drugs that have a high binding to plasma proteins, which may partition differently depending on how the ‘plasma / serum’ separation is performed.

Erwin Berthier: In addition to Neil’s comment on dried plasma strategies that are being developed and commercialized there are a number of solution for liquid plasma using a range of techniques including centrifugation and filtration. These represent exciting developments to truly provide samples with a high diagnostic quality from a home setting.

Melanie Anderson: Mobile phlebotomy is gaining increased usage as well, especially in light of the pandemic. These approaches provide traditional liquid sample collection by a phlebotomist/nurse but provide at home collection. Small, mobile centrifuges enable appropriate spin down for plasma.

Enaksha Wichrmsinhee: A device/technique that can be used at home to collect a liquid plasma/serum sample (that can then be sent to the lab as a liquid sample) would have a wide applicability.  Hopefully there will be additional techniques/devices can enable this in the near future.

QWhat about the collection of interstitial fluid?

Neil Spooner: Interstitial fluid can be sampled using suction blisters on the skin, microdialysis, or microperfusion, all of which require expert technique. A more recent possible alternative is the use of patches containing microneedles which are applied to the skin surface. The volumes collected are small (ca. 1 uL), which can result in issues with the sensitivity of the analytical assay. These references cover the area well [1, 2].

Erwin Berthier: The debate over interstitial fluid is somewhat moot since one has to prove concordance of the analytes in the sample with venous samples. It is very hard to know exactly the percentage of capillary blood and interstitial fluid in the sample, but as long as the data demonstrates substantial equivalence it would be considered by most, including the FDA, to be a valid sample.

References
[1] Samant PP and Prausnitz MR. Mechanisms of sampling interstitial fluid from skin using a microneedle patch. PNAS. 115(18), 4583–4588 (2018).
[2] Lei BUW and Prow TW. A review of microsampling techniques and their social impact. Biomed. Microdevices. 21, 81 (2019).

The opinions expressed in this feature are those of the author and do not necessarily reflect the views of Bioanalysis Zone or Future Science Group.