Multicenter, Signatera™ Genome-guided interventional trial will evaluate different treatment approaches in HR+/HER2- breast cancer

Natera, Inc. (NASDAQ: NTRA), a global leader in cell-free DNA and precision medicine, and MEDSIR (Medica Scientia Innovation Research), a global leader in oncology research, today announced their collaboration on the MiRaDoR (NCT05708235) study, which is a multicenter, phase II clinical trial in hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer.

Breast cancer is the most common cancer in women worldwide, with approximately 2.3 million new cases diagnosed in 2022.¹ Despite advances in treatment, recurrence remains a key concern for patients with HR+/HER2- disease, which represents roughly 70% of all breast cancer cases.²

Funded by F. Hoffman-La Roche Ltd., and sponsored by MEDSIR, MiRaDoR will use Signatera Genome to evaluate the efficacy of different therapeutic approaches in early-stage HR+/HER2- breast cancer. Up to 60 patients who are Signatera-positive without clinical nor radiological evidence of disease recurrence will be sequentially enrolled into one of four treatment arms:

• Arm A: Standard of care endocrine therapy given during the first 90-day period, then patients switch to Arms B, C or D
• Arm B: Giredestrant (oral selective estrogen receptor degrader)
• Arm C: Giredestrant plus Abemaciclib (CDK4/6 inhibitor)
• Arm D: Giredestrant plus Inavolisib (PIK3CA inhibitor; for patients with PIK3CA mutations)

The trial will enable investigators to evaluate serial circulating-tumor DNA (ctDNA) levels in each treatment arm as a predictive marker of treatment response. The study’s primary endpoint is the proportion of patients who have achieved a 90% decrease or clearance in baseline ctDNA after three months of treatment. Participants will have additional Signatera testing at 6, 9 and 12 months, and every six months thereafter until study treatment discontinuation. Results may help determine if specific therapy combinations are more effective in terms of ctDNA decrease than standard of care endocrine treatment.

“Uniting Signatera Genome’s ability to detect molecular residual disease with genomic profiling creates a new standard for precision oncology clinical trials,” said Angel Rodriguez, M.D., senior medical director of oncology at Natera. “In the MiRaDoR trial, investigators are moving beyond surveillance; they are also characterizing the specific genomic driver, PIK3CA, and no longer just asking ‘is the cancer back?’ but also answering 'how do we treat it?’”

Enrollment for MiRaDoR is underway, with several U.K. sites already active and additional site activations expected in Europe in 2026.

References

1. World Health Organization. Breast Cancer Fact Sheet. Last updated August 14, 2025. Available at: https://www.who.int/news-room/fact-sheets/detail/breast-cancer
2. American Cancer Society. Breast Cancer Facts & Figures 2024-2025. Atlanta: American Cancer Society, Inc. 2024.

About Natera

Natera™ is a global leader in cell-free DNA and precision medicine, dedicated to oncology, women’s health, and organ health. We aim to make personalized genetic testing and diagnostics part of the standard of care to protect health and inform earlier, more targeted interventions that help lead to longer, healthier lives. Natera’s tests are supported by more than 325 peer-reviewed publications that demonstrate excellent performance. Natera operates ISO 13485-certified and CAP-accredited laboratories certified under the Clinical Laboratory Improvement Amendments (CLIA) in Austin, Texas, and San Carlos, California, and through Foresight Diagnostics, its subsidiary, operates an ISO 27001-certified and CAP-accredited laboratory certified under CLIA in Boulder, Colorado. For more information, visit www.natera.com.

About MEDSIR

Established in 2012, MEDSIR prides itself on working closely with its strategic partners to drive innovation in oncology research. Operating in Spain and the United States, the company provides end-to-end clinical trial management, from study design to publication, with an extensive global network of experts and integrated technology to streamline the process. The company offers proof-of-concept support and a strategic approach that enables research partners to benefit from the best of both worlds: industry clinical research and investigator-driven trials. With the aim of promoting independent research worldwide, MEDSIR has formed a strategic alliance with Oncoclínicas, the leading oncology group in Brazil, which offers outstanding research potential in South America. For further information: www.medsir.org

Forward-Looking Statements (Natera)

All statements other than statements of historical facts contained in this press release are forward-looking statements and are not a representation that Natera’s plans, estimates, or expectations will be achieved. These forward-looking statements represent Natera’s expectations as of the date of this press release, and Natera disclaims any obligation to update the forward-looking statements. These forward-looking statements are subject to known and unknown risks and uncertainties that may cause actual results to differ materially, including with respect to whether the results of clinical or other studies will support the use of our product offerings, the impact of results of such studies, our expectations of the reliability, accuracy, and performance of our tests, or of the benefits of our tests and product offerings to patients, providers, and payers. Additional risks and uncertainties are discussed in greater detail in "Risk Factors" in Natera’s recent filings on Forms 10-K and 10-Q, and in other filings Natera makes with the SEC from time to time. These documents are available at www.natera.com/investors and www.sec.gov.

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