The use of Biodesix’ predictive cancer therapy assay VeriStrat has been validated in a Phase III trial originally carried out to evaluate GlaxoSmithKline’s Tykerb®/Tyverb® (lapatinib) as an addition to Novartis’ Femara® (letrozole) in breast cancer patients. Data from the trial demonstrated that VeriStrat could be used to identify a group of patients with worse progression-free survival (PFS) when treated with Femara alone, independent of Her2 status.
VeriStrat is a serum proteomic test currently used to identify NSCLC patients who are likely to respond well, or poorly, to treatment using EGFR inhibitors. The Phase III Tykerb trial (designated EGF30008), was the first to evaluate VeriStat in breast cancer and also the first to assess the assay with an endocrine agent, Biodesix notes.
The EGF30008 compared Femara monotherapy, with Femara plus Tykerb. Prior to the start of therapy, serum samples from 81% of the 1,286 enrolled patients were classified as either VeriStrat Good or VeriStrat Poor. Results following therapy showed that in the Femara treatment arm, patients who tested VeriStrat Good had a median PFS of 10.8 months, while those who tested VeriStrat Poor demonstrated a PFS of just 2.8 months. In contrast, in the Femara plus Tykerb arm, there was very little difference in PFS among patients who tested VeriStrat Good and VeriStrat negative. In the HER2 positive population, both VeriStrat groups benefitted from the addition of Tykerb to Femara, but interestingly, the firm notes, in the Her2 negative population there was a trend toward increase in PFS for patients who tested VeriStrat Poor. Data from the study were presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.
“It’s encouraging to see that our test not only identifies a group of hormone receptor-positive patients with poor outcomes on endocrine therapy, but also has predictive power, showing that this group of patients can achieve similar outcomes to other patients when Tykerb is added to the treatment regimen, regardless of their Her2 status," comments David Brunel, Biodesix CEO.
VeriStrat is the first product developed using Biodesix’ ProTS® platform, which enables the routine use of MALDI mass spectrometry for clinical diagnostics. The ProTS effectively processes mass spectral data obtained from biological samples such as blood or tissue, to generate spectra that can be reliably compared between samples. ProTS data analysis then identifies statistically significant features that differentiate the spectra from distinct clinical groups of samples. These features are then incorporated into a novel classifier algorithm that evaluates the spectra generated from a patient sample and assigns it to clinical groups, such as patients who respond well to a therapy and those who don’t.
VeriStrat testing for NSCLC patient stratification is carried out at Biodesix’ CLIA laboratory. The firm is in addition validating the clinical utility of VeriStrat in other solid tumors, including colorectal, pancreas, and head and neck cancers, and alongside targeted therapies.