By Ruchi Jhonsa, Ph.D.
Circumventing the need for invasive procedures, liquid biopsies are increasingly becoming an important option to decide about the presence or absence of cancer. This method extracts circulating cell-free DNA in the blood to detect key mutations associated with certain cancers. It is popular with the patients who can do the test at the convenience of their house and obtain test results, which have better reproducibility than tissue biopsies.
In August, the USFDA approved Foundation medicine’s FoundationOne Liquid CDx, a liquid biopsy test covering all solid tumors that are qualified under Medicare and are eligible as per the centers for medicare and Medicaid services national coverage decision memo criteria. Now the test is available for three more indications following the agency’s backing. The new indications are for Piqray (alpelisib) in advanced or metastatic breast cancer, Rubraca (rucaparib) in advanced ovarian cancer and Alecensa (alectinib) in a certain type of metastatic non-small cell lung cancer (mNSCLC). Just days back, the test was approved as a companion diagnostic for Bayer’s VITRAKVI.
FoundationOne liquid CDx is a qualitative next-generation sequencing-based diagnostic test that can match a patient to specific therapies depending upon the mutation they harbor. It analyses the largest genomic region of any FDA approved liquid biopsy test that identifies substitutions, insertions, deletions, copy number alteration in 324 genes along with gene rearrangements, genomic signatures including microsatellite instability and tumor mutational burden.
“FoundationOne Liquid CDx offers oncologists an important and minimally invasive tool to consider when making treatment decisions for their patients, regardless of the type of cancer they have,” said Brian Alexander, M.D., M.P.H., chief medical officer at Foundation Medicine. “These three additional companion diagnostic claims expand the test’s clinical utility into breast and ovarian cancer, demonstrating our commitment to bringing precision medicine to more patients, and we plan to continue working with our biopharma partners to increase that reach.”
PI3K-Positive Breast Cancers
Patients with HR+/HER2-breast cancer are treated with HR targeted therapies. However, approximately 40% of patients living with HR+/HER2 negative breast cancer also harbor a mutation in the PIK3CA gene and are less responsive to HR2 therapies. This underscores the therapeutic importance of mutation testing. Last year, the FDA approved a companion diagnostic test, Qiagen’s therascreen PIK3CA RGQ PCR kit, to detect the PIK3CA mutation in a tissue or a liquid biopsy. This enabled detection of PIK3CA mutation and facilitated oncologists in selecting patients who may benefit from targeted treatments. While this test works on the principle of DNA amplification, FoundationMedicine’s test works at the sequencing level.
This gives an edge to FMI’s kit as it determines the presence or absence of a mutation with more certainty than an RT-PCR based kit. Similar to Qiagen’s kit, the FoundationOne test will help in determining if a patient needs treatment with Piqray, the first kinase inhibitor from Novartis indicated for use in HER2 negative, HR2 positive, and PIK3CA positive breast cancer.
BRCA Mutation Harboring Ovarian Cancers
FoundationOne assay was already geared to test metastatic castration-resistant prostate cancer that can be treated using Rubraca when it was first approved. Now it will also test another indication that can be treated by Rubraca, i.e., advanced ovarian cancer. This is a big deal for the community affected by ovarian cancers (one in four women) who can now test for the BRCA1/BRCA2 genetic mutation simply by a blood test and get the right treatment for the problem.
“Tumors with BRCA mutations are by far the most responsive to PARP inhibitors in metastatic castration-resistant prostate cancer, and when we started the development of Rubraca for mCRPC, we knew it was important to develop a plasma-based companion diagnostic for physician and patient ease of use,” said Patrick J. Mahaffy, president, and CEO of Clovis Oncology, in a press release. “What we could not have foreseen was how important a plasma-based test would be in this COVID-19 environment, in which even important procedures, such as tissue-based biopsies, can be difficult to schedule for patients.”
About 5% of NSCLC patients have ALK mutations. FoundationOne liquid test is particularly helpful for patients with ALK mutations for whom current diagnostic methods are not suitable, such as for those who cannot provide tissue samples due to insufficient or absent tumor tissue or where tissue diagnostics are not available.
“Obtaining tumor tissue for biomarker testing can be a challenge in many people with cancer and, as a result, some may not receive optimal treatment for their disease,” said Sandra Horning, MD, chief medical officer and head of Global Product Development.
“Validated and comprehensive liquid biopsy tests are critical to help physicians find the best possible treatment approach for patients with advanced cancer and for whom tissue testing isn’t feasible. Identifying ALK fusions can be particularly challenging, and the FoundationOne Liquid can accurately predict which patients can respond to therapy,” said Brian Alexander, MD, chief medical officer of Foundation Medicine.
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