Roche launched a new automated in vitro diagnostic to detect tropomyosin receptor kinase proteins in cancer, which the company hopes will have potential use in a range of solid tumor types and site-agnostic targeted therapies—such as Bayer and Loxo Oncology’s newly approved pancancer drug, Vitrakvi.
Used for analytic studies, the Ventana pan-TRK immunohistochemistry assay identifies wild-type and chimeric fusion proteins while measuring the prevalence of TRK in tumor tissue.
TRK-fusion proteins have been identified in more than 30 common solid tumors, including lung, thyroid and sarcoma. And while wild-type protein expression is generally low, it can be substantial in some neuroendocrine tumors.
In some rare cancers—such as infantile fibrosarcoma, secretory and juvenile breast cancer, and mammary analogue secretory cancers of the salivary glands—TRK proteins are likely to be the defining genetic feature, according to the Big Biotech.
“As the first test of its kind, the Ventana pan-TRK (EPR17341) Assay provides an important new tool to help us better understand the role of TRK protein expression, particularly fusions in cancer,” said Jill German, head of Roche Tissue Diagnostics. The assay is available on Roche's BenchMark series of IHC/ISH automated staining instruments.
The assay detects TRK proteins related to neurotrophic tyrosine receptor kinase genes (NTRK) or oncogenes that can drive cancer progression, which are currently being studied in clinical trials for targeted therapies.
Late last year, Roche bought out Ignyta for $1.7 billion in cash, obtaining its tyrosine-kinase inhibitor aimed at tumors with ROS1 or NTRK fusion mutations. Entrectinib is currently being studied in non-small cell lung cancer, pancreatic cancer, sarcomas, thyroid cancer, salivary cancer, gastrointestinal stromal tumors and metastatic cancers with an unknown primary origin site.
At the ESMO annual meeting in October, Roche and its Genentech unit presented new phase 2 data showing the drug shrank NTRK fusion-positive tumors in 57.4% of treated patients across 10 different cancer types.
But they’ll be competing with Bayer and Loxo’s pan-cancer NTRK inhibitor, larotrectinib, which was approved by the FDA this week as Vitrakvi. At ESMO this year, it demonstrated an overall response rate of 81% in over 120 patients.
One of the obstacles Bayer and Loxo face in launching the drug is that NTRK genetic testing is not routine and may cause difficulty in identifying eligible patients for treatments—though the drug’s peak sales have been estimated anywhere from $700 million to $1 billion, with a price tag of nearly $400,000 per year.
Following the approval, Leerink Partners analyst Andrew Berens wrote that Bayer’s sales team will work with prescribing oncologists, while Loxo's staff will “focus on interfacing with lab directors and pathologists to raise awareness around tumor genomic profiling.”
Loxo previously signed a next-generation sequencing companion diagnostic deal with Illumina, using its TruSight Tumor 170 as the basis for a test that identifies NTRK fusions.