Novel Predictive Biomarkers for Non-Small Cell Lung Cancer - Episode 1
Gregory J. Riely, MD, PhD: Over the past 15 years, we’ve had a dramatic change in the tissue that’s needed to diagnosis non—small cell lung cancer. Certainly, it wasn’t too long ago, and when many of us trained, that you could get fine needle aspiration that showed a few cancer cells on a slide. You were content that you had a diagnosis of non–small cell lung cancer and felt that you had enough information to treat the patient.
Over the past 15 years, we’ve had a dramatic alteration. In addition to knowing that it’s non—small cell lung cancer, you have to understand the tumor histology: Is it a squamous cell histology, adenocarcinoma, a large cell? You have to have enough tissue to do predictive biomarkers. These predictive biomarkers can include PD-L1, as well as tumor mutation testing. You can’t get all that information off 1 slide from a fine needle aspiration. You have to get more tissue than that. Sometimes the tissue can be obtained through a transbronchial biopsy, an EBUS, or a regular bronchoscopy. Sometimes you can do it with a CT-guided biopsy. Sometimes you can do it with a thoracic surgeon through an open biopsy. Whatever technique you use, you have to get enough material, and material of the right kind, to allow for the mutation or biomarker testing that you want.
Importantly, one of the key biomarkers for lung cancer is a marker called PD-L1. PD-L1 is not FDA approved as an assay on tumor cytology. To be truly compliant with the biomarker guidelines, you should get a biopsy specimen—that would mean a CT-guided biopsy or even a needle in a transbronchial biopsy. It has to be a histology specimen and not a cytology specimen. Overall, all these techniques, over the years, have really moved forward in getting more tissue from our patients with lung cancer, and it allows us to test all the biomarkers that we want to test.
Jared Weiss, MD: The first step to ensuring that suitable tissue for molecular analysis is collected during a lung biopsy starts with a conversation prior to that biopsy. Ideally, this conversation happens in a multidisciplinary tumor board, where the various practitioners to whom that testing would be of relevance are present. That conversation starts with a discussion regarding the appropriate place to test, to ensure that adequate tissue is collected and to ensure that it’s done safely and comfortably for the patient. In general, more peripheral lesions are accessed via a CT-guided route, and more central lesions, increasingly, are being accessed through an endobronchial ultrasound.
That conversation continues with what’s going to be important for this patient. This comes to the question of preanalytics—how the tissue is going to be handled once it’s obtained. This idea of tissue stewardship may get a little bit mundane, but it’s really critical for the right thing to happen. The person obtaining the biopsy and the pathologist need to have good communication with each other and should understand what we’re using this for. For example, if we’re biopsying bone for the purpose of molecular characterization, it’s really important to not decalcify the specimen. If we already know that the person has adenocarcinoma of the lung, if we’re doing a biopsy to get additional molecular information that was not previously obtained, then it’s important to not use up the specimen by doing a lot of IHC tests proving that it’s lung cancer, and so on.
Transcript Edited for Clarity