Personalis, Inc. (Nasdaq: PSNL), a leader in advanced genomics for precision oncology, today announced the publication of the PREDICT-DNA study in the Journal of Clinical Oncology. The article, "The Pathologic Response Evaluation and Detection In Circulating Tumor-DNA (PREDICT-DNA) study: Ultrasensitive ctDNA Assessment of Breast Cancer Minimal Residual Disease," showed that ultrasensitive molecular residual disease (MRD) testing with NeXT Personal can perform better than current standard approaches in predicting patient outcomes following neoadjuvant therapy (NAT).

The prospective study followed 227 patients with Triple-Negative (TNBC) and HER2+ breast cancer across more than 24 leading US cancer centers. The results demonstrate the ability of NeXT Personal to provide a more precise risk-stratification for patients who have received NAT.

A key finding of the study was the necessity of the ultrasensitive range for accurately tracking patient response to neoadjuvant therapy. Of note, 55% of all ctDNA detections following NAT occurred at levels below 100 parts per million, detections that could be missed with less sensitive tests.

“Many breast cancer patients receive neoadjuvant therapy as standard of care, prior to surgery. The results of this study suggest that an ultrasensitive ctDNA assay like NeXT Personal could help patients better understand their response to neoadjuvant therapy, with the potential to help inform the need for additional therapy,” said Richard Chen, MD, Chief Medical Officer and Executive Vice President, R&D at Personalis. “The publication of this data is important as we look to expand reimbursement and improve the tools used in neoadjuvant monitoring.”

Key study highlights include:

• High Prognostic Power: Detectable ctDNA post-NAT was associated with a 4 to 9 times higher likelihood of relapse.
• Superior to Traditional Metrics: In multivariate analyses, ctDNA status was the most significant independent prognostic signal, performing better than nodal status, tumor grade, and pathologic complete response (pCR) status. In addition, ctDNA detection post-NAT was a stronger predictor of recurrence than pCR status.
• Identification of Low Risk: Patients who were ctDNA-negative post-NAT showed excellent outcomes, regardless of pCR status.
• Post-Surgical Relapse Prediction: Patients with detectable ctDNA up to 12 months post-surgery were more than 100 times more likely to experience disease recurrence.

“We partnered with Personalis because their technology offers a level of sensitivity down to 1 to 3 parts per million that allows for a higher cancer detection rate," said Dr. Ben Park, MD, PhD, Director of the Vanderbilt-Ingram Cancer Center. "The PREDICT-DNA results show that if a patient clears their ctDNA, their outcomes are excellent even if residual disease is found at surgery. Conversely, detectable ctDNA signals a very high risk. These insights allow us to more precisely risk-stratify breast cancer patients in future trials and clinical practice.”

The findings reinforce the NeXT Personal test’s ability to detect ctDNA at ultrasensitive levels, providing a window for earlier clinical intervention that other approaches may miss. The NeXT Personal test achieves ultrasensitive detection of small traces of ctDNA from a patient’s blood sample using a personalized approach that tracks up to ~1,800 tumor-specific variants unique to each patient’s tumor.

About Personalis, Inc.

At Personalis, we are transforming the active management of cancer through breakthrough personalized testing. We aim to drive a new paradigm for cancer management, guiding care throughout the patient journey. Our highly sensitive assays combine tumor-and-normal profiling with proprietary algorithms to deliver advanced insights even as cancer evolves over time. Our products are designed to detect minimal residual disease (MRD) and recurrence at the earliest timepoints, enable selection of targeted therapies based on ultra-comprehensive genomic profiling, and enhance biomarker strategy for drug development. Personalis is based in Fremont, California. To learn more, visit www.personalis.com and connect with us on LinkedIn and X (Twitter).

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include all statements that are not historical facts, including statements relating to the attributes, advantages, sensitivity, and clinical relevance (including prognostic power, risk-stratification capabilities and superiority to traditional metrics) of the NeXT Personal test and the potential impact or expected benefits of the PREDICT-DNA study. Such forward-looking statements involve known and unknown risks and uncertainties and other factors that may cause actual results to differ materially from any anticipated results or expectations expressed or implied by such statements, including the risks, uncertainties and other factors that relate to Personalis’ ability to demonstrate attributes, advantages or clinical validity or utility of the NeXT Personal test, including the NeXT Personal MRD assay remaining unique in its ability to detect traces of cancer in the ultrasensitive range; future clinical data differing from the clinical data previously presented or expected results; the ability of Personalis to expand reimbursement for, or the rate of adoption and use of, the NeXT Personal test; changes in health care policy, which could increase Personalis’ costs, decrease Personalis’ revenue, and impact sales of and reimbursement for Personalis’ tests; the impact of competition and macroeconomic factors on Personalis’ business; the partnering and/or collaboration arrangements that Personalis has entered into or may enter into in the future, which may not be successful, or may terminate, which could adversely impact Personalis’ business or affect its ability to develop and commercialize its services and products; having a limited number of suppliers; and customer concentration. These and other potential risks and uncertainties that could cause actual results to differ materially from the results predicted in these forward-looking statements are described under the captions “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in Personalis’ Annual Report on Form 10-K for the year ended December 31, 2025, filed with the Securities and Exchange Commission (SEC) on February 26, 2026. All information provided in this release is as of the date of this press release, and any forward-looking statements contained herein are based on assumptions that we believe to be reasonable as of this date. Undue reliance should not be placed on the forward-looking statements in this press release, which are based on information available to us on the date hereof. Personalis undertakes no duty to update this information unless required by law.

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