Establishing a Strong Assay Foundation
Before we can conceptualize IVD product configurations, we must establish assay inputs which include, but are not limited to:
- Identify the need for the test, e.g. diagnose breast cancer or sepsis, identify bacteria, monitor glucose levels, etc.
- Identify the target biomarker or indicator, i.e. is there a biomarker or markers that are correlated to a condition or disease?
- Identify where the target can be found, e.g. urine, blood, saliva, etc.
- Determine the availability or frequency of appearance of the target; when are levels the highest?
- Determine if and how the target can be detected
- Determine sampling frequency, e.g. single sample or continuous monitoring
- Determine assay method stability
- Statistical information to confirm assay reproducibility
A well-developed and robust IVD assay will help to decrease the overall timeline and cost of a product development project. The first step, which is primarily driven by the demands of the market, is to determine which condition or disease monitoring is needed. After careful selection of a target and development of the assay foundation, you may move on to product design for concept generation, prototyping, and feasibility testing.
The Assay Development Pipeline
Identify the Target
- Determine which target biomarker or indicator is specific or directly correlated to the condition or disease of interest
- Rationale: Selecting the appropriate target reduces ambiguity when using an assay to diagnose a disease or monitor a condition
- There may be one or several associated biomarkers (e.g. RNA, DNA, antibody, small molecules, antigen, etc.)
- Selecting specific biomarker(s) or indicator(s) is critical and impacts assay sensitivity and specificity
Examples
- Human chorionic gonadotropin as an indicator for pregnancy
- Spike protein as an indicator for the presence of SARS-CoV-2
Identify Target Location
- Determine the biodistribution of the target biomarker or indicator
- Target may be found in multiple tissues
- Rationale: Selecting the appropriate sample type ensures capture of high concentrations of the target biomarker
- Targeting high concentrations increase signal-to-noise and can improve sensitivity
- Non-invasive sampling is typically favored and improves use adherence
Examples
- Sampling human chorionic gonadotropin from blood or urine
- Sampling SARS-CoV-2 from blood or a nasal swab
Determine Target Availability
- Determine the availability of circulating target biomarker or indicator
- Rationale: Some targets can remain available or persist in circulation for hours or days, or continuously at different concentrations
- Understanding what the limitations are and when to sample is critical to improving assay sensitivity
Examples
- Glucose is consistently present in the bloodstream, albeit in different concentrations
- Genes from SARS-CoV-2 are not consistently available and differ in concentrations
- Prostate specific antigen levels may increase as prostate cancer progresses
Identify Detection Methods
- Determine methods to detect or quantify the target biomarker or indicator
- Rationale: Selecting the appropriate detection method ensures that optimal sensitivity can be achieved
- Selecting the detection method is also influenced by commercialization goals
- Reagents that dilute or stabilize the sample of interest for a specific detection method require careful selection
Examples
- Human chorionic gonadotropin can be detected using a single-use disposable lateral flow assay
- Nucleocapsid protein from SARS-CoV-2 can be detected using a single-use disposable lateral flow assay
- Genes for SARS-CoV-2 can be detected using polymerase chain reaction (PCR)
Identify Sampling Frequency
- Determine the frequency at which to sample the target biomarker or indicator
- Rationale: Understanding when to sample is necessary to ensure that the intended detection timeframe of target is captured
- Sampling frequency often correlates with target availability
- Sampling duration will also determine if a power source is required
Examples
- Proteins from SARS-CoV-2 can be sampled as needed; no power source required for a single-use lateral flow assay
- Glucose monitoring can occur continuously via a battery-powered wearable device
Determine Assay Method Stability
- Determine what aspect of the assay could impact product stability
- Rationale: Understanding method stability informs how long an IVD can be used or stored, and therefore, how the IVD is designed
Examples
- Assay reagents may be require automated mixing, which impacts product design
- Assay reagents may require cold storage, which impacts shelf-life and shipping
- Assay requires temperature-dependent incubation, which may require a small battery
Assay Confirmation
- Confirm that the assay is accurate and precise
- Rationale: A robust and reproducible assay will help to reduce the product development timeline and cost
- Statistical information is important, e.g. coefficient of variation <20%, 95% confidence interval, etc.
- Statistical information is also used to assess sensitivity and specificity
Examples
- Assay was able to detect cancer marker with a sensitivity of 90.6% (95% CI 81.9–99.2)
- ELISA inter-assay precision has a coefficient of variation lower than 10%
Product Embodiment Vision
- Design preliminary concepts for the IVD product
- Rationale: A vision of the product will guide the engineering team in their concept generation work
- Early concepts can be ideas, sketches or a prototype
- Design can feature enhancements, e.g. temperature sensor, sound
Examples
- Prototype of a microfluidic consumable
- Sketch of a high-throughput automated device to isolate nucleic acid
- Product embodiment wish list, e.g., “Size of a mobile phone” or “Water-resistant”
Veranex understands that timeline and costs for product development can be impacted if an assay is not quite ready for translation (i.e., high specificity and sensitivity not yet achieved) into an in-vitro diagnostic product. In addition to our service offering for medical technologies development, we provide solutions for any step in the assay development pipeline described, even before you have performed laboratory testing. Veranex assay support includes basic and applied research for all the assay inputs described, as well as procurement of reagents and donor samples, test execution, and generation of assay protocols. Our goal is to ensure that all your assay workstream goals are met for every step of the IVD product lifecycle.