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Oncology Advances January 2017

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Dana-Farber/Brigham and Women's Cancer Center | 5 Liquid Biopsy for Lung Cancer Delivers Faster Diagnosis and Targeted Treatments was highest in patients with multiple metastatic sites and in patients with hepatic or bone metastases. "When taking into account the additional time needed to schedule and obtain results from surgical biopsy, we can begin treatment up to a month sooner in patients with these muta- tions by using the liquid biopsy," said Geoffrey R. Oxnard, MD, senior author of the study and a medical oncologist in the Lowe Center for Thoracic Oncology at Dana-Farber/Brigham and Women's Cancer Center. "The test also enables us to avoid repeated tissue biopsies and their associated risks for patients with positive plasma genotyping results." The liquid biopsy analysis, which is performed at the Center for Advanced Molecular Diagnostics at Brigham and Women's Hospital, is now being offered for appropriate NSCLC patients at DF/BWCC. Results are generally available in two-to-three days. "We believe that our study was the first prospective study of the use of ddPCR-based plasma genotyping to detect EGFR and KRAS mutations," said Dr. Oxnard. "Our results demon- strate the accuracy, reliability, and practicality of this technique for patients with NSCLC, as well as the potential of utilizing this approach for early prediction of treatment response." A Woman in Her 80s with Metastatic EGFR Mutant Non-Small-Cell Lung Cancer With Acquired Resistance to Erlotinib Geoffrey R. Oxnard, MD Medical Oncologist, Lowe Center for Thoracic Oncology, Dana-Farber/Brigham and Women's Cancer Center Developed by experts at Dana-Farber/Brigham and Women's Cancer Center (DF/BWCC), a new blood test using rapid plasma genotyping to detect epidermal growth factor recep- tor (EGFR) and KRAS mutations is enabling much more rapid diagnosis and commencement of targeted therapies for pa- tients with non-small cell lung cancer (NSCLC). The liquid biopsy examines tumor-derived cell-free DNA using droplet digital polymerase chain reaction (ddPCR) technology. The test was developed at the Belfer Center for Applied Can- cer Science at Dana-Farber Cancer Institute and validated for clinical use in a study recently published in JAMA Oncology (JAMA Oncol. 2016 Apr 7. doi: 10.1001/jamaoncol. 2016. 0173.). The study included 180 patients with NSCLC (120 newly diagnosed patients and 60 patients with acquired re- sistance). Each participant also underwent a conventional tis- sue biopsy. The results of the liquid biopsies were then compared to the tissue biopsy results. The median turnaround time for liquid biopsies was three days, compared to 12 days for tissue biopsies in newly diag- nosed patients and 27 days in drug-resistant patients. Liquid biopsy was found to be highly accurate. In newly diagnosed patients, the predictive value of plasma ddPCR was 100 per- cent for the primary EGFR mutation and the KRAS mutation. For patients with the EGFR T790M acquired resistance muta- tion, the predictive value of the ddPCR test was 79 percent, in part because the blood test was able to detect some cases of EGFR T790M that were missed by tissue genotyping. The re- searchers also found that the test's sensitivity for the mutations Symptomatic progression of pulmonary and bone metastases were noted (primary lung lesion labeled). Empirical single-agent chemotherapy or best supportive care alone were considered given the patient's age and comorbidities. However, plasma droplet digital polymerase chain reaction (ddPCR) was performed and the result returned the next day, revealing 806 copies/mL of EGFR T790M. The patient underwent rebiopsy, which confirmed EGFR T790M, and the patient was able to start therapy with osimertinib – a novel third-generation EGFR kinase inhibitor – with excellent clinical and radiographic response. Importantly, the plasma ddPCR T790M result was returned 24 days before the results of the repeated tissue biopsy were available. JAMA Oncol. 2016;2(8):1014-1022. 1-877-332-4294

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