FDA Approves FoundationOne CDx as Companion Diagnostic for Larotrectinib


The FoundationOne CDx is now approved by the FDA as a companion diagnostic for larotrectinib (Vitrakvi) to identify patients with NTRK fusions across all solid tumors.

The FDA has approved the FoundationOne CDx to be used as a companion diagnostic for larotrectinib (Vitrakvi), an agent which is currently FDA approved for the treatment of adult and pediatric patients with solid tumors that have a NTRK gene fusion without a known acquired resistance mutation, are metastatic or where surgical resection is likely to result in severe morbidity, and have no satisfactory alternative treatments or that have progressed following treatment, according to Foundation Medicine, the developer of the companion diagnostic.

Currently the only FDA approved tissue based comprehensive genomic profiling test, the FoundationOne CDx is now approved to detect NTRK1/2/3 fusions across all solid tumor types and to identify patients who may benefit from treatment with larotrectinib.

“Taking a comprehensive and validated approach to genomic testing is critical for all advanced cancer patients, but especially for those harboring rare mutations that can be missed with alternative testing methods,” Brian Alexander, MD, MPH, chief medical officer at Foundation Medicine, said in a press release. “Not only will this approval improve access to genomic testing and reinforce the role it plays in rare cancers, but it also confirms the incredible progress made toward tumor-agnostic cancer care. We’re proud of the impact this will have on NTRK fusion positive cancer patients.”

The approval of larotrectinib was based on data from 3 multicenter, open-label, single-arm clinical trials, including LOXO-TRK-14001 (NCT02122913), SCOUT (NCT02637687), and NAVIGATE (NCT02576431). The primary end points were overall response rate and response duration, as determined by a blinded independent review committee according to RECIST 1.1.

Identification of positive NTRK gene fusion status was prospectively determined in local laboratories using next generation sequencing or fluorescence in situ hybridization (FISH). Overall, NTRK gene fusions were inferred in 3 pediatric patients with infantile fibrosarcoma who had a documented ETV6 translocation by FISH.

The clinical validation to support the FoundationOne CDx NTRK companion diagnostic approval was then brought about through a clinical bridging study between the local clinical trial assays and the FoundationOne CDx.

Notably, the FoundationOne CDx is the first broad companion diagnostic approved by the FDA that is clinically and analytically validated for solid tumors. The tissue-based comprehensive genomic profiling test is currently approved as a companion diagnostic for more than 20 targeted therapies.

“Many patients with rare conditions, like NTRK fusion positive cancer have limited treatment options and poor access to targeted therapies,” Susan Spinosa, co-chair and patient founder of the NTRKers, said in the release. “This companion diagnostic approval is a critical step forward in addressing this challenge as it provides this patient population with broader access to comprehensive genomic testing and appropriate treatment options.”

Importantly though, the FoundationOne CDx is for prescription use only and is designed to be used as a companion diagnostic to identify patients who may benefit from treatment with certain targeted therapies in accordance with their approved therapeutic product labeling. In addition, the tissue based comprehensive genomic profiling test is intended to provide tumor mutation profiling to be used by qualified health care professionals in accordance with professional guidelines for patients with solid malignant neoplasms.

However, use of the test does not guarantee a patient will be matched to a treatment. Further, a negative result does not rule out the presence of an alteration and some patients may require a biopsy.


FoundationOne®CDx Receives FDA-Approval as a Companion Diagnostic for VITRAKVI®(larotrectinib) to Identify Patients with NTRK Fusions Across All Solid Tumors [news release]. Cambridge, Massachusetts. Published October 23, 2020. Accessed October 26, 2020. https://www.foundationmedicine.com/press-releases/c90da36c-205d-4b8d-9848-dfcb970da47a

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