As we mentioned in Part 1 of our series, there are some pitfalls that need to be avoided when using a commercially available immunoassay kit for biomarker quantification. Many of these can be overcome in the earliest phases of kit selection and validation, if you have the right biomarker work plan in place from the start.
We all know the saying “it all starts with a plan”, and novel biomarker assay development is no different. The objective of a biomarker work plan is to define the intended use of the data that the assay will generate, because this usage dictates the type of method validation that will be required.
Putting the Plan in Place
The specific needs of your project must be at the forefront of any biomarker work plan your organization develops. All relevant stakeholders should be involved to ensure the plan is tailored to the unique parameters of your study. The plan should consider a range of evaluation points, including: analytes of interest; endogenous analyte stability; sample matrix; expected sample numbers over time; sample volume; sample collection process; storage stability; analytical range; and sensitivity and precision requirements. An early understanding of these potential data points will work to inform and justify the level of method validation required later.
This actionable biomarker work plan will help guide the development of a robust method validation plan to characterize and validate the assay to your predefined level of rigor.
Establishing Validation Rigor and Acceptance Criteria
Defining the rigor of method validation is a major part of the overall biomarker work plan. This segment of the plan would include provisions for changes that will be needed to adapt your kit-based method for its intended use and your specific assay parameters. The intended use of assay data, as defined in the larger biomarker work plan, should guide you to the appropriate level of method validation required. For example, for exploratory biomarkers studies which may be conducted for internal decision-making, a partial validation that looks at only a few analytical parameters may be enough, and even a semi-quantitative or a qualitative assay may be sufficient. However, by the time your biomarker journey has moved to the point that may be used for patient diagnosis contributing to drug label and dosing information, the level of validation is extremely advanced and calls for a very high level of confidence in the analytical method performance and is subject to different regulatory requirements than in the exploratory biomarker world.
Selecting the Right Commercial Kit Vendor
Once you have defined your biomarker work plan, including potentially necessary kit adaptation and validation rigor level requirements, you are ready to select your commercial immunoassay kit vendor – however, this is not always a straightforward process. I have found that it can be very difficult to identify a vendor who can meet your study’s exact needs. Objectively, it will be important to choose a vendor that has the greatest level of assay characterization information available for your kit. It will be critical to obtain the kit data to assess the amount of work your team will need to do to fill in information gaps, and obviously the less, the better. It is also helpful if the vendor is an organization that offers a user-friendly technical service and supplies flexibility.
Evaluating these key points and others often requires a vast amount of time and energy, and to aid in decision-making our industry has developed several open scientific forums where scientists can share their kit evaluation experience and findings, such as those in the Foundations for the National Institutes of Health (FNIH), Biomarkers Consortium, Predictive Safety Testing Consortium, and AAPS Ligand Binding Assay Bioanalytical Focus Group. You can also take advantage of existing vendor information others have shared to start your search or confirm your decision.
The next step in this process will be to choose and assess the appropriate kit to purchase from your chosen vendor, and determine which method adaptations need to be made in order to meet your assay needs. Read more about how to best carry out those tasks next in Part 3 of this blog series. In the meantime, feel free to reach out to me with any questions about how BioAgilitix approaches commercial immunoassay kit evaluation for biomarker assays.