Pulmotype was derived by taking advantage of insights from gene expression studies that established the extensive diversity in the molecular physiology of lung tumor histological types. Hundreds of antibodies were created and screened for their ability to distinguish different subtypes of cancer and further screened for their applicability in a tool for specifically discriminating lung adenocarcinomas from squamous cell carcinoma. For more information on the technology behind the Pulmotype test go to the Technology Section of the AGI website.

	Development

Pulmotype was initially developed in a study in which AGI applied its lung 'Panel of Diversity' to a 550 patient cohort of lung cancer specimens from the Clearview Cancer Institute of Huntsville, AL. This protein expression dataset was used to identify markers with a significant association for discriminating adenocarcinoma from squamous cell carcinoma histology. These markers were used in turn to derive a linear model that combines results for selected squamous markers (SLC7A5, CK5/6, TRIM29) with adenocarcinoma markers (MUC1, CEACAM5) into a weighted classifier for distinguishing adenocarcinoma from squamous cell carcinoma.

	Validation

In order to test the association between histological type assignment by our five antibody Pulmotype test and a pathologist’s morphological assessment, three independent lung carcinoma tissue array cohorts comprising 1,111 samples in total, assembled at separate institutions (The Cleveland Clinic Foundation, Universitätsspital Zürich, and Invitromed), were stained with the Pulmotype test. In these three independent cohorts, the classification of tumors by the five antibody test was strongly associated with pathologist morphologic assessment. We also tested Pulmotype against a commonly used 2-marker panel of TTF-1 and TP63. Both Pulmotype and TTF1/TP63 panel had similarly low misclassification rates on the validation cohorts. However the percentage of patients remaining unclassifiable by TTF1/TP63 was twice that of Pulmotype. In clinical practice this result is significant because, for example, the therapy Avastin is given to only those NSCLC patients who have been classified with a non-squamous histotype.

The results of these studies, initially published via poster at ASCO-NCI-EORTC 2008 and recently published in Modern Pathology, suggest Pulmotype may have an immediate role in the clinic for helping pathologists distinguish lung carcinoma histological types. The results also suggest that, if validated in prospectively defined clinical trials, this classifier might identify candidates for targeted therapy that are over-looked with current diagnostic approaches.