Beyond PD-L1 assays
How Genentech envisions gene signature test that could replace PD-L1 assays
Data from Genentech Inc.’s Phase III IMpower150 trial of Tecentriq atezolizumab in first-line non-small cell lung cancer provides the company with its first hard data showing what work lies ahead before it will be ready to deploy a gene signature biomarker to supplant PD-L1 assays.
In IMpower150, the Roche unit’s T effector (Teff) gene expression panel, did not show much difference on progression-free survival (PFS) compared with its PD-L1 assay. Previous studies in different populations, however, showed the Teff signature may be able to identify a bigger group of patients who would benefit from Tecentriq than the PD-L1 assay finds, without any loss in the degree of benefit.
Going forward, Genentech thinks more exploratory work is required to refine the panel, and to identify populations in which Teff can do a better job than PD-L1 assays at predicting who will and will not respond to Tecentriq.
Currently, immunohistochemistry (IHC) assays for PD-L1 expression are the most widely used tests for selecting patients to be treated with PD-1 or PD-L1 inhibitors. Three of the four available assays use a mAb targeting PD-L1 to stain tumor cells. Genentech’s