News Center Myriad Genetics Announces Publication of a Prospective Clinical Study of the EndoPredict® Test in Women with Early-Stage Breast Cancer Myriad Genetics Announces Publication of a Prospective Clinical Study of the EndoPredict® Test in Women with Early-Stage Breast Cancer June 4, 2020 Products EndoPredict Predicts Response to Neoadjuvant Chemotherapy and Endocrine Therapy SALT LAKE CITY, June 04, 2020 (GLOBE NEWSWIRE) — Myriad Genetics, Inc. (NASDAQ: MYGN, “Myriad” or the “Company”), a global leader in molecular diagnostics and precision medicine, today announced the publication of a prospective study demonstrating that the EndoPredict® test predicts which patients with ER+, HER2- early-stage breast cancer will benefit from neoadjuvant therapy. The article titled, “The EndoPredict score predicts response to neoadjuvant chemotherapy and neoendocrine therapy in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer patients from the ABCSG-34 trial,” appeared online in the European Journal of Cancer. “This study demonstrated that the EndoPredict (EP) test predicted response to neoadjuvant chemotherapy or neoadjuvant endocrine therapy in women with ER+, HER2 negative early-stage breast cancer,” said Peter Dubsky, M.D., lead author, speaking on behalf of the Austrian Breast and Colorectal Cancer Study Group (ABCSG). “Based on these findings and prior studies, we are confident the EndoPredict test can add valuable information to aid in personalized treatment selection in neoadjuvant therapy and provides an important basis for future design of neoadjuvant clinical trials.” The primary objective of this prospective study was to test the predictive value of the EndoPredict test regarding tumor response after neoadjuvant chemotherapy (NaCT) or neoadjuvant endocrine therapy (NET) within the ABCSG-34 trial. The analysis included data from 217 women with HR+ breast cancer. Of these, 134 patients were assigned to receive NaCT (eight cycles of anthracycline/taxane) according to aggressive clinico-pathologic tumor features. The remaining 83 patients were clinically identified as having luminal A-like types of breast cancer and were assigned to receive NET (six months of letrozole). The primary endpoint was residual cancer burden RCB0/I (i.e., good tumor response) vs. RCB II/III (i.e., poor tumor response) at time of surgery. In the neoadjuvant chemotherapy group, 125 patients had high EP scores and nine had a low EP score. The results show that 26.4 percent of those with a high score showed a good tumor response (RCB0/I) to neoadjuvant chemotherapy, while all patients with a low score showed only a poor tumor response (Table 1). In the “luminal A” group receiving neoendocrine therapy, 39 patients had a high EP score and 44 had a low EP score. The results show that 27.3 percent of those with a low EndoPredict score and 7.7 percent with a high score achieved excellent tumor response (RCB0/I) to neoendocrine therapy (Table 1). Table. 1 EndoPredict Low Score EndoPredict High Score Predictive Performance EndoPredict Score (p-value) Response to Neoadjuvant Chemotherapy 0.0 % 26.4 % p=0.0001 Response to Endocrine Therapy 27.3 % 7.7 % P=0.015 “In this prospective study, we demonstrated that the EndoPredict test is a useful tool pre-operatively,” said Ralf Kronenwett, M.D., director of International Medical Affairs at Myriad. “In two distinct ER-positive, HER2-negative cohorts selected by clinicians to receive neoadjuvant chemotherapy or neoadjuvant endocrine therapy, EndoPredict identified patients with poor neoadjuvant treatment response. Clinicians can use information to determine who might forgo these therapies prior to surgery.” About EndoPredict EndoPredict is a second-generation, 12-gene molecular prognostic test for patients diagnosed with breast cancer. The test provides vital information that helps clinicians devise personalized treatment plans for their patients. EndoPredict has been validated in more than 4,000 patients with node-negative and node-positive cancer and has been used clinically in more than 20,000 patients. In contrast to first-generation multigene prognostic tests, EndoPredict detects the likelihood of late metastases (i.e., metastasis formation after more than five years) and, therefore, can guide treatment decisions regarding the need for chemotherapy, as well as extended anti-hormonal therapy. Accordingly, therapy decisions backed by EndoPredict confer a high level of diagnostic safety. For more information, please visit: www.endopredict.com. About Myriad Genetics Myriad Genetics Inc., is a leading personalized medicine company dedicated to being a trusted advisor transforming patient lives worldwide with pioneering molecular diagnostics. Myriad discovers and commercializes molecular diagnostic tests that: determine the risk of developing disease, accurately diagnose disease, assess the risk of disease progression, and guide treatment decisions across six major medical specialties where molecular diagnostics can significantly improve patient care and lower healthcare costs. Myriad is focused on three strategic imperatives: transitioning and expanding its hereditary cancer testing markets, diversifying its product portfolio through the introduction of new products and increasing the revenue contribution from international markets. For more information on how Myriad is making a difference, please visit the Company’s website: www.myriad.com. Myriad, the Myriad logo, BART, BRACAnalysis, Colaris, Colaris AP, myPath, myRisk, Myriad myRisk, myRisk Hereditary Cancer, myChoice, myPlan, BRACAnalysis CDx, Tumor BRACAnalysis CDx, myChoice CDx, Vectra, Prequel, Foresight, GeneSight, riskScore and Prolaris are trademarks or registered trademarks of Myriad Genetics, Inc. or its wholly owned subsidiaries in the United States and foreign countries. MYGN-F, MYGN-G. Safe Harbor Statement This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements related to the EndoPredict test adding valuable information to aid in personalized treatment selection in neoadjuvant therapy and providing an important basis for future design of neoadjuvant clinical trials; and the Company’s strategic directives under the caption “About Myriad Genetics.” These “forward-looking statements” are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties associated with COVID-19, including its possible effects on our operations and the demand for our products and services; our ability to efficiently and flexibly manage our business amid uncertainties related to COVID-19; the risk that sales and profit margins of our molecular diagnostic tests and pharmaceutical and clinical services may decline; risks related to our ability to transition from our existing product portfolio to our new tests, including unexpected costs and delays; risks related to decisions or changes in governmental or private insurers’ reimbursement levels for our tests or our ability to obtain reimbursement for our new tests at comparable levels to our existing tests; risks related to increased competition and the development of new competing tests and services; the risk that we may be unable to develop or achieve commercial success for additional molecular diagnostic tests and pharmaceutical and clinical services in a timely manner, or at all; the risk that we may not successfully develop new markets for our molecular diagnostic tests and pharmaceutical and clinical services, including our ability to successfully generate revenue outside the United States; the risk that licenses to the technology underlying our molecular diagnostic tests and pharmaceutical and clinical services and any future tests and services are terminated or cannot be maintained on satisfactory terms; risks related to delays or other problems with operating our laboratory testing facilities and our healthcare clinic; risks related to public concern over genetic testing in general or our tests in particular; risks related to regulatory requirements or enforcement in the United States and foreign countries and changes in the structure of the healthcare system or healthcare payment systems; risks related to our ability to obtain new corporate collaborations or licenses and acquire new technologies or businesses on satisfactory terms, if at all; risks related to our ability to successfully integrate and derive benefits from any technologies or businesses that we license or acquire; risks related to our projections about our business, results of operations and financial condition; risks related to the potential market opportunity for our products and services; the risk that we or our licensors may be unable to protect or that third parties will infringe the proprietary technologies underlying our tests; the risk of patent-infringement claims or challenges to the validity of our patents or other intellectual property; risks related to changes in intellectual property laws covering our molecular diagnostic tests and pharmaceutical and clinical services and patents or enforcement in the United States and foreign countries, such as the Supreme Court decisions in Mayo Collab. Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012), Ass’n for Molecular Pathology v. Myriad Genetics, Inc., 569 U.S. 576 (2013), and Alice Corp. v. CLS Bank Int’l, 573 U.S. 208 (2014); risks of new, changing and competitive technologies and regulations in the United States and internationally; the risk that we may be unable to comply with financial operating covenants under our credit or lending agreements; the risk that we will be unable to pay, when due, amounts due under our credit or lending agreements; and other factors discussed under the heading “Risk Factors” contained in Item 1A of our most recent Annual Report on Form 10-K for the fiscal year ended June 30, 2019, which has been filed with the Securities and Exchange Commission, as well as any updates to those risk factors filed from time to time in our Quarterly Reports on Form 10-Q or Current Reports on Form 8-K. All information in this press release is as of the date of the release, and Myriad undertakes no duty to update this information unless required by law. Media Contact: Jared Maxwell Investor Contact: Scott Gleason (801) 505-5027 (801) 584-1143 jmaxwell@myriad.com sgleason@myriad.com