Clinical OMICS

JAN-FEB 2019

Healthcare magazine for research scientists, labs, pathologists, hospitals, cancer centers, physicians and biopharma companies providing news articles, expert interviews and videos about molecular diagnostics in precision medicine

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Page 44 of 51 January/February 2019 Clinical OMICs 43 CHRIS ANDERSON Editor in Chief Biomarker-Based Cancer Drug Approval F or only the second time, the U.S. Food and Drug Administration (FDA) approved a drug, named Vitrakvi (larotrectinib), for an array of cancers based on a specific biomarker instead of tissue of origin. The drug, approved in late Novem- ber, is indicated for advanced solid tumor cancers that have an NTRK fusion—essentially a hybrid of two genes—that is known to cause uncon- trolled cell growth. The first biomarker-driven drug approved by the FDA wasKeytruda (pem- brolizumab) for microsatellite instability-high and mismatch repair-deficiency cancers. Both drugs received their tissue-agnostic nods from the FDA under their accelerated approval process, and because Keytruda had previously been approved in 2014 for treatment of advanced melanoma, Vitrakvi is the first drug to receive its initial approval based on a biomarker. The Vitrakvi approval came about six weeks after the release by the FDA of a guidance doc- ument that essentially paves the way for more drug approvals based on biomarkers. The guid- ance, titled "Developing Targeted Therapies in Low-Frequency Molecular Subsets of a Dis- ease," is further indication of it acknowledging the legitimacy of drugs developed based on the molecular profile of a disease and the specific alterations that cause them. "Today's approval marks another step in an important shift toward treating cancers based on their tumor genetics rather than their site of origin in the body," said FDA Commissioner Scott Gottlieb, M.D. in a statement announcing the approval. "This new site-agnostic oncology therapy isn't specific to a cancer arising in a particu- lar body organ, such as breast or colon cancer. Its approval reflects advances in the use of biomarkers to guide drug development and the more targeted delivery of medicine." NTRK fusions are found in many types of solid tumors that affect both children and adults. In the clinical trials, Vitrakvi showed clinical benefit across numerous unique tumor types, including lung, thyroid, melanoma, GIST, colon, soft tissue sarcoma, salivary gland and infantile fibrosar- coma. The drug showed an overall response rate of 75% and a complete response rate of 22%. "We were waiting for a drug like this to come into our program, a drug that really worked not in just subsets of cancers, but in any cancer that had that particular mutation," said David Hyman, M.D., chief of early drug development at Memorial Sloan Kettering Cancer Center, where a portion of the clinical trial was conducted. While the approval is significant in terms of regulatory policy, the drug's developers, Bayer and Loxo Oncology, now face the task of actu- ally finding patients who can benefit from the therapy. Fewer than 1% of solid tumor cancers are driven by NTRK fusions, though its occur- rence varies across all cancers. This translates to between 2,000 and 3,000 patients each year in the U.S. who could benefit from the drug. Testing methods for the biomarker includes both next- gen sequencing (NGS) and fluorescence in situ hybridization (FISH). Like many highly-targeted treatments, the annual cost of Viktravi also comes with a high price tag—as much as $393,000 annually, though it runs as low as about $11,000 per month for some pediatric treatments. Sensitive to these concerns, Bayer announced two programs that would provide financial assistance to patients taking the drug. Under one program, Bayer would refund the costs incurred for patients not experiencing clinical benefit within 90 days of beginning treatment. A second program "pro- vides comprehensive reimbursement support and patient assistance services," according to the company. Ca-ssis / iStock / Getty Images

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