Guardant Health and Blueprint Medicines present real-world data identifying EGFR C797X mutation as most common resistance mechanism to osimertinib therapy at IASLC 2022 World Conference on Lung Cancer

• Analysis utilizing GuardantINFORM™ real-world evidence platform shows cumulative incidence of EGFR C797X mutation was 12.5 percent in NSCLC patients likely to progress after first-line osimertinib treatment
• Study demonstrates need to identify C797X-driven resistance and tailor therapy options appropriately for patients with EGFR-mutant NSCLC

Guardant Health Inc. (Nasdaq: GH), a leading precision oncology company, and Blueprint Medicines Corporation (Nasdaq: BPMC) announced today they are presenting new data demonstrating that the EGFR C797X mutation is the most common resistance mechanism to osimertinib therapy for patients with advanced non-small cell lung cancer (NSCLC). The results are being reported today at the International Association for the Study of Lung Cancer (IASLC) 2022 World Conference on Lung Cancer in Vienna.

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“This real-world study improves our understanding of how resistance mutations to osimertinib emerge over time, with new insights on when EGFR C797X mutations overtake MET amplifications as the most commonly acquired resistance mechanism,” said Suresh Ramalingam, M.D., FACP, FASCO, executive director of Winship Cancer Institute of Emory University, who served as the principal investigator for the study. “The analysis characterizes the increased frequency of EGFR C797X mutations as patients are treated with first-line osimertinib for longer durations, reinforcing the need for next-generation EGFR inhibitors to address C797X-driven resistance.”

A collaborative effort between Guardant Health, Blueprint Medicines and Winship Cancer Institute, the study analyzed de-identified clinical and genomic data using the GuardantINFORM real-world evidence platform, which includes more than 65,000 adults with advanced NSCLC. The analysis evaluated genomics data from the Guardant360 circulating tumor DNA (ctDNA) test for more than 2,000 patients who had any EGFR mutation and treatment with osimertinib, a third-generation EGFR TKI (tyrosine kinase inhibitor) and the current standard of care for patients with advanced-stage NSCLC with common EGFR mutations. The study incorporated ctDNA results up to five years after patients initiated osimertinib therapy.

Cumulatively, the analysis indicated that EGFR C797X mutations were 1.25 times more common than MET amplification when osimertinib was used as first-line therapy and 2.4 times more common when it was used as second-line therapy. In patients likely to experience disease progression after first-line treatment with osimertinib, the cumulative incidence of EGFR C797X mutations was 12.5 percent. MET amplifications were the most common resistance mutation in the first year of osimertinib treatment, and EGFR C797X mutations exceeded the rate of MET amplifications in years two through five.

“This study is an excellent example of how real-world data from the GuardantINFORM platform can be used to shed new light on resistance mechanisms in lung cancer therapy,” said Helmy Eltoukhy, Guardant Health chairman and co-CEO. “The analysis provided critical insights about resistance mutations that can contribute to the development of more effective therapies for lung cancer.”

“We are committed to developing transformative precision therapies that prevent or overcome treatment resistance, which represents an important medical need for patients with EGFR-mutant, non-small cell lung cancer,” said Becker Hewes, M.D., Chief Medical Officer at Blueprint Medicines. “Our collaboration with Guardant Health advances our efforts to characterize dynamic treatment resistance patterns in lung cancer, helping inform therapeutic strategies, including novel combinations, that may prolong patient benefit.”

About GuardantINFORM

The GuardantINFORM clinical-genomic platform is intended to help accelerate research and development of the next generation of cancer therapeutics by offering biopharma partners an in-silico platform that combines de-identified longitudinal clinical information and genomic data collected from the Guardant360 liquid biopsy test. With data from more than 225,000 patients diagnosed with locally advanced and metastatic cancers, this robust dataset offers real-world insights into anti-cancer therapy use in the clinic, tumor evolution, and treatment resistance throughout each patient’s treatment journey for many advanced solid tumor cancers, including non-small cell lung, breast, colon and prostate.

About Guardant Health

Guardant Health is a leading precision oncology company focused on helping conquer cancer globally through use of its proprietary tests, vast data sets and advanced analytics. The Guardant Health oncology platform leverages capabilities to drive commercial adoption, improve patient clinical outcomes and lower healthcare costs across all stages of the cancer care continuum. Guardant Health has commercially launched Guardant360^®, Guardant360^® CDx, Guardant360 TissueNext™, Guardant360 Response™, and GuardantOMNI^® tests for advanced stage cancer patients, and Guardant Reveal™ for early-stage cancer patients. The Guardant Health screening portfolio, including the Shield^TM test, aims to address the needs of individuals eligible for cancer screening. For more information, visit guardanthealth.com and follow the company on LinkedIn and Twitter.

About Blueprint Medicines

Blueprint Medicines is a global precision therapy company that invents life-changing therapies for people with cancer and blood disorders. Applying an approach that is both precise and agile, we create medicines that selectively target genetic drivers, with the goal of staying one step ahead across stages of disease. Since 2011, we have leveraged our research platform, including expertise in molecular targeting and world-class drug design capabilities, to rapidly and reproducibly translate science into a broad pipeline of precision therapies. Today, we are delivering approved medicines directly to patients in the United States and Europe, and we are globally advancing multiple programs for systemic mastocytosis, lung cancer and other genomically defined cancers, and cancer immunotherapy. For more information, visit www.BlueprintMedicines.com and follow us on Twitter (@BlueprintMeds) and LinkedIn.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding the potential utilities, values, benefits and advantages of Guardant Health’s liquid biopsy tests or assays; statements regarding Blueprint Medicines’ plans, strategies, timelines and expectations for clinical trials, trial cohorts and indications; the anticipated benefits of Blueprint Medicines’ collaborative study with Guardant Health identifying the EGFR C797X mutation as the most common resistance mechanism to osimertinib; the potential benefits of Blueprint Medicines’ current or future approved drugs or drug candidates in treating patients; and Blueprint Medicines’ strategy, business plans and focus. The words “aim,” “may,” “will,” “could,” “would,” “should,” “expect,” “plan,” “anticipate,” “intend,” “believe,” “estimate,” “predict,” “project,” “potential,” “continue,” “target” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release are based on Guardant Health’s and Blueprint Medicines’ respective managements’ current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks and uncertainties related to the impact of the COVID-19 pandemic to each company’s business, operations, strategy, goals and anticipated milestones, including Blueprint Medicines’ ongoing and planned research and discovery activities, ability to conduct ongoing and planned clinical trials, clinical supply of current or future drug candidates, commercial supply of current or future approved products, and launching, marketing and selling current or future approved products; Blueprint Medicines’ ability and plans in establishing a commercial infrastructure, and successfully launching, marketing and selling current or future approved products, including AYVAKIT® (avapritinib) and GAVRETO® (pralsetinib); Blueprint Medicines’ ability to successfully expand the approved indications for AYVAKIT and GAVRETO or obtain marketing and reimbursement approvals for AYVAKIT and GAVRETO in additional geographies in the future; the delay of any current or planned clinical trials or the development of Blueprint Medicines’ current or future drug candidates; Blueprint Medicines’ advancement of multiple early-stage efforts; Blueprint Medicines’ ability to successfully demonstrate the safety and efficacy of its drug candidates and gain approval of its drug candidates on a timely basis, if at all; the preclinical and clinical results for Blueprint Medicines’ drug candidates, which may not support further development of such drug candidates either as monotherapies or in combination with other agents or may impact the anticipated timing of data or regulatory submissions; the timing of the initiation of clinical trials and trial cohorts at clinical trial sites and patient enrollment rates; actions of regulatory agencies, which may affect the initiation, timing and progress of clinical trials and marketing applications; Blueprint Medicines’ ability to develop and commercialize companion diagnostic tests for its current and future drug candidates; Blueprint Medicines’ ability to successfully expand its operations, research platform and portfolio of therapeutic candidates, and the timing and costs thereof; Blueprint Medicines’ ability to realize the anticipated benefits of its executive leadership transition plan; and the success of Blueprint Medicines’ current and future acquisitions, collaborations, partnerships or licensing arrangements. These and other risks and uncertainties are described in greater detail in the section entitled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operation” and elsewhere in each company’s most recent Annual Report on Form 10-K, and any current and periodic reports filed with the Securities and Exchange Commission thereafter. Any forward-looking statements contained in this press release represent Guardant Health’s and Blueprint Medicines’ views only as of the date hereof and should not be relied upon as representing its views as of any subsequent date. Except as required by law, Guardant Health and Blueprint Medicines explicitly disclaim any obligation to update any forward-looking statements.

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