Interstitial and diffuse lung disease
New genomic classifier
A confident diagnosis of idiopathic pulmonary fibrosis (IPF) relies on the radiographic pattern of usual interstitial pneumonitis (UIP), although in some cases, histologic confirmation is warranted. Transbronchial biopsy (TBBx) does not provide adequate tissue for diagnosis, thus patients are subjected to the risk of a surgical biopsy. A promising new test can increase confidence in the diagnosis of IPF. The Envisia Genomic Classifier (Veracyte) is a recently approved test to aid in the diagnosis of IPF. It utilizes 190 genes and RNA sequencing, combined with machine learning, to create an algorithm that determines the presence of UIP on samples derived from TBBx.
A proof-of-principle study described the characteristics of the genomic classifier in distinguishing UIP for 53 training subjects and 31 test subjects. To ensure validation, this new test was compared with a diagnosis determined by histopathologic review from expert pathologists. Specificity was 86% and sensitivity 63% in distinguishing UIP vs non-UIP patterns. Although false-negatives were a concern due to IPFs heterogeneous involvement of the lung, combining multiple specimens from a single patient increased accuracy.
Dr. Samantha D'Annunzio
The recently-published BRAVE study was a validation and utilization study, proving the test’s success in identifying UIP on TBBx samples. The test was again compared with diagnostic histopathology, demonstrating 88% specificity and 70% sensitivity. In addition, two multidisciplinary teams had an 86% agreement on diagnoses when using pathology vs the genomic classifier. The classifier is commercially available and is covered by Medicare in the United States.
As with all new technology, it is expected that its use will increase in the future and that we will learn more about how, and in whom, to best utilize this tool.
Samantha D’Annunzio, MD
Steering Committee Member
References
Pankratz DG, et al. Ann Am Thorac Soc. 2017;14[11]1646.
Raghu G, et al. Lancet Respir Med. 2019 Jun;7(6):487.