ABSTRACT
Improvement in technical, regulatory, and clinical areas is likely to significantly increase the number of new oncology drugs requiring CDx tests over the next few decades. Immunohistochemistry (IHC) is one of the most frequently used CDx assay formats with Polymerase Chain Reaction (PCR) and ISH-based methods. Because IHC is simple to perform and well established in most hospitals, its simplicity and popularity are the biggest strength for its use as a CDx assay. However, several weaknesses of Sanger sequencing prevent it from being widely used as a CDx assay. Sanger sequencing was the gold standard for most genetic analyses until Next-Generation Sequencing (NGS) became available in 2004. For a multivariate analysis, multiple independent experiments should be done when using Sanger sequencing, whereas only one test is enough for NGS. ISH methods can detect both known and novel fusion types, whereas PCR or targeted NGS methods are likely to miss a novel type of fusion not covered by primers or probes.
