Improving FDA-approved IHC tests for breast cancer requires more accurate, quantitative assays to address the limitations in reproducibility and accuracy faced by pathologists, according to David Rimm, MD, PhD. Current tests often yield inconsistent results, with concordance rates as low as 25%, compared to biomarkers like EGFR mutations, which achieve near-perfect concordance. Rimm emphasizes shifting from qualitative scoring to quantitative measurements using automated technology, such as digitization, artificial intelligence, and fluorescence-based methods. These advancements aim to bring pathology to the same level of precision as blood tests, ensuring more reliable diagnostic results for breast cancer patients.
Improving the accuracy of FDA-approved immunohistochemistry (IHC) tests for breast cancer is crucial due to the limitations in current testing methods and the challenges pathologists face in consistently reproducing results. David Rimm, MD, PhD, suggests that transitioning to more quantitative assays, supported by automated technology, is the solution to these challenges. During the 2024 San Antonio Breast Cancer Symposium, Rimm emphasized the need for a shift from qualitative scoring to quantitative measurements to enhance consistency and reliability in IHC testing.
Rimm, who holds the Anthony M. Brady Professorship of Pathology at the Yale School of Medicine and leads several research and tissue analysis initiatives at the Yale Cancer Center, discussed the limitations of current IHC tests. He highlighted how these tests often place undue strain on pathologists, expecting them to achieve results that may be beyond human reproducibility. This disconnect has significant implications for treatment decisions, as inconsistent results can lead to suboptimal patient care.
One of the key challenges lies in the concordance rates between IHC tests performed by different pathologists. Rimm noted that while concordance can be as low as 25%, other biomarkers, such as EGFR mutations, achieve near-perfect concordance (99%). This disparity underscores the urgent need for more reliable testing methods.
To address these issues, Rimm advocates for the development and adoption of quantitative IHC assays. These assays leverage automated technology to digitize and quantify optical density, significantly improving accuracy and consistency. Additionally, research into artificial intelligence and quantitative fluorescence methods, which provide precise measurements akin to laboratory blood tests, holds promise for revolutionizing IHC testing. Rimm’s team is at the forefront of this innovation, developing assays that measure HER2 protein concentration in attomoles per square millimeter, a level of precision reminiscent of blood glucose testing.
The future of IHC testing, according to Rimm, lies in making these quantitative methods widely available. This shift would bring pathological analysis into line with the precision and standardization seen in clinical laboratory tests, ensuring that results are both accurate and reproducible. Rimm stressed that the goal is to find solutions rather than assign blame, emphasizing the importance of collaboration among pathologists, oncologists, and researchers to enhance the reliability of IHC testing in breast cancer care.
