Contributed Commentary by Erika Leonard, Director of R&D and Technical Services, Vector Laboratories
July 24, 2026 | Growing momentum in biomarker discovery, advancing analytical technologies, and a shift toward personalized medicine have created unprecedented possibilities for diagnostic development. The pace at which this progress translates to novel, widely adopted, clinically validated diagnostic tools remains slow, but not for lack of innovation. Many diagnostic assays do not fail during early research; they fail when transitioning from research-use-only (RUO) environments into clinically validated diagnostic tests.
As assays move toward in vitro diagnostic (IVD) applications, the development landscape changes dramatically: reproducibility expectations increase, documentation and quality systems become more rigorous, and reagent sourcing and lot-to-lot consistency must withstand regulatory scrutiny. If research workflows are not designed with clinical scalability in mind, developers can face a host of pitfalls on the path to IVD development, from reagent variability and supply continuity challenges to gaps in documentation or quality processes.
The RUO-to-clinical transition remains one of the most vulnerable stages of diagnostic development, and diagnostic developers—particularly small or emerging teams—must learn how to design assays with regulatory readiness, scalability, and long-term reproducibility in mind from the earliest stages of development. By addressing these challenges earlier in the development process, developers can reduce costly redesigns and accelerate the path from promising research assay to reliable clinical diagnostic.
Understanding the Intricacies of an Assay
When a diagnostic developer has an early assay concept in mind, two broad sources of failure often come into play: the limits of current technology or reagents, and the challenges associated with their biomarkers or specimens of interest. In the first instance, the developer may discover upon further exploration that the available tools and reagents cannot achieve necessary levels of sensitivity or specificity. In the second example, developers struggle to achieve consistent assay performance due to variables in the biomarker of interest, the clinical specimens being analyzed, or the antibodies used in the assay.
These challenges underscore the importance of gaining a comprehensive understanding of antibody-target relationships from the earliest phases of development. For example, a common diagnostic target like PD-L1 presents several nuances: it is a large, complex protein with many possible binding sites, some of which may be more or less accessible to different antibodies in Western blot or ELISA formats versus immunohistochemical (IHC) or immunofluorescent (IF) assays. Early assay optimization thus involves dialing in on how the antigen target is presented across different sample preparation methods and achieving a robust signal-to-noise ratio in the assay output of choice.
Here, developers may prevent future struggles in their clinical transition by choosing reagents carefully. In many cases, vendors producing RUO antibody reagents may build their product with less rigor than IVD-ready components. For example, lot-to-lot variability and characterization data across limited input samples can lead to inconsistencies as an assay developer seeks to advance their test. Comprehensive testing of a reagent across various input sample types is key to truly optimizing assay performance, as differences between biological substrates or even source populations can yield unexpected differences.
Building a Foundation of Scalability and Consistency
As development progresses, scalability and consistency become just as important as analytical performance. A reagent that performs well in a small-scale research setting may present significant challenges when an assay moves toward clinical validation and commercialization. Diagnostic developers should therefore evaluate potential reagent and antibody suppliers not only on current performance, but also on their ability to support long-term manufacturing needs. This includes assessing factors such as lot-to-lot consistency, supply continuity, documentation practices, and change control procedures. Vendors with established quality systems and rigorous characterization programs are often better positioned to support the demands of clinical assay development, helping reduce the risk of unexpected variability later in the process.
For this reason, conversations about regulatory readiness should begin much earlier than one might anticipate. Engaging with suppliers early allows assay developers to better understand how reagents are manufactured, qualified, and monitored over time, while also identifying whether additional documentation or validation data may be required for future regulatory submissions. Even for teams working in an RUO environment, developing an awareness of IVD requirements can inform smarter design decisions from the outset. By considering scalability, quality management, and supply chain stability alongside assay performance, developers can build a stronger foundation for a successful transition from research assay to clinically validated diagnostic.
Ensuring Lasting Performance
As an assay approaches clinical validation and commercialization, developers must ensure that the foundational elements required for long-term success are firmly in place. Beyond demonstrating analytical and clinical performance, regulatory submissions require extensive documentation supporting assay reproducibility, manufacturing controls, and quality management processes.
Reagent stability studies are a particularly important component of this effort, providing evidence that critical assay components will maintain performance throughout their intended shelf life and under expected storage and transport conditions. Addressing these considerations proactively can help prevent delays during regulatory review and reduce the risk of performance issues emerging after launch.
Ultimately, successful diagnostic development requires looking beyond the immediate goal of generating promising research data. The transition from RUO assay to clinically validated IVD is not a single event, but a process that depends on thoughtful planning, rigorous validation, and strong partnerships throughout development.
By considering scalability, reproducibility, supplier quality, and regulatory expectations from the earliest stages, developers can build assays that are not only scientifically sound but also positioned for long-term clinical adoption. In an era where new biomarkers and therapeutic approaches are rapidly transforming possibilities in precision medicine, those who design with the end goal in mind will be best equipped to translate innovation into meaningful patient impact.
Erika Leonard is director of R&D and technical services at Vector Laboratories, where she leads research and technical teams focused on advancing technologies for life science research and diagnostics. With more than two decades of experience in assay development, antibody technologies, and diagnostic workflows, she works closely with researchers to address complex scientific and technical challenges. She can be reached out at Erika.Leonard@vectorlabs.com.