Biomarkers for Infectious Disease: Current Challenges and Advancements

Kaitlin Searfoss:
Hi, everyone. Welcome to this podcast from Cambridge Healthtech Institute for Next Generation Diagnostic Summit which runs August 19th through 20th, 2015 in Washington D.C. I'm Kaitlin Searfoss, associate conference producer.

We have with us today one of our chairs from the Molecular Diagnostics for Infectious Disease Conference, Kate Simon, PhD, Senior Consultant at Biologics Consulting Group, Inc.

Dr. Simon, thank you for joining us. Given your background at the FDA, and your current role in consulting, what are the challenges in establishing reference methods for new biomarkers of infectious diseases?

Kate Simon:
In having this conversation, it is important to be clear what we are talking about when we say the words, "biomarker" and "reference methods." There are many different definitions of "biomarker" from different sources. One suitable definition can be found in the Webster dictionary, which is, "A distinctive biological or biologically-derived indicator of a process, event, or condition." A common definition of a "reference method" is an analytic procedure, sufficiently free of random or systematic error, to make it useful for validating proposed new analytic procedures for the same analyte.

Initially, most biomarkers are validated via their ability to predict or identify a target condition in the host by looking at the association of that biomarker with the presence of the target condition as defined by standard clinical practice or clinical truth.

Eventually, the clinical efficacy of a biomarker will become established enough that a procedure or test to detect that biomaker can be characterized as being sufficiently free of random or systematic error to serve as a reference method for the same biomarker, or a biomarker for the same target condition.

What happens when no clinical truth for the target condition is currently established? You may have a biomarker that you believe can differentiate a colonized infection from a disease-causing infection, but what if there is a significant proportion of patients in your clinical study from whom several microbes are identified that could, potentially, be colonizers or the positive agent of patient symptoms?

What are you options when truly establishing clinical truths for the target condition is not possible due to ethical complications? For example, if the goal is to validate a biomarker that you believe will enable enhance anti-microbial stewardship, it might be possible to determine clinical truths for which patients require anit-microbial therapy by withholding anti-microbials from everyone to see who will have a robust enough immune response to get well without treatment. This is clearly not an ethical choice when the infection is capable of producing significant morbidity or mortality.

In short, the challenges depend on the intended use of the biomarker and the associated clinical syndromes that are being investigated.

Kaitlin Searfoss:
In terms of testing technology for infectious disease biomarkers, what are the biggest challenges that scientists and technology developers are facing in 2015 and beyond?

Kate Simon:
It is clear that the recent advances in testing technologies for future diagnostics have thrown the door wide open for new indications that previously were not possible. Sequencing technologies, in particular, have undergone major advances that will only continue to get faster and more affordable. The challenge will be to properly interpret the vast quantities of information that these new technologies are capable of generating.

Kaitlin Searfoss:
What are you most looking forward to at the Molecular Diagnostics for Infectious Disease Conference?

Kate Simon:
I'm actually looking forward to hearing Dr. Tsalik speak on host gene expressing classifiers for infectious disease. He gave a very interesting talk last year on a similar topic, so it'll be good to see what his research has uncovered in the past year.

Kaitlin Searfoss:
Dr. Simon, thank you for your time and insights today.

Kate Simon:
Thank you.

Kaitlin Searfoss:
That was Kate Simon, PhD, Senior Consultant at Biologics Consulting Group, Inc. She'll be speaking at the Molecular Diagnostics For Infectious Disease Conference at the upcoming Next Generation Diagnostic Summit taking place August 19th through 20th, 2015 in Washington D.C. I'm Kaitlin Searfoss. Thank you for listening.