<div id="readability-page-1"><article>FREMONT, Calif.--(BUSINESS WIRE)--Personalis, Inc. (Nasdaq: PSNL), a leader in advanced genomics for precision oncology, today announced the publication of a new study in Clinical Cancer Research, a journal of the American Association for Cancer Research (AACR). The paper, titled &#34;Broad Utility of Ultrasensitive Analysis of ctDNA Dynamics across Solid Tumors Treated with Immunotherapy,&#34; details results from Dr. Rodrigo Toledo and a leading team at the Vall d’Hebron Institute of Oncology (VHIO) in Barcelona, Spain. The study provides compelling clinical evidence that the company’s ultra-sensitive, tumor-informed molecular residual disease (MRD) assay, NeXT Personal®, can effectively predict patient outcomes across a diverse set of cancers and immunotherapy modalities.The study analyzed 202 patients with stage IV solid tumors—spanning 24 different cancer types—treated with immune checkpoint inhibitors and other immunotherapies. Utilizing a personalized testing approach that tracks up to ~1,800 tumor-specific variants unique to each patient’s tumor, the NeXT Personal test achieves ultrasensitive detection of small traces of circulating tumor DNA (ctDNA) from a patient’s blood sample.Key findings published in Clinical Cancer Research include:<ul><li>High Sensitivity: The test detected ctDNA in 98% of patients at baseline across all 24 tumor types, demonstrating robust performance even in a diverse set of cancers.</li><li>Early ctDNA Dynamics are Highly Prognostic: Patients who demonstrated decreases in ctDNA levels early in immunotherapy treatment had significantly higher overall survival. Conversely, patients with increasing ctDNA levels early while on immunotherapy had a zero percent overall response rate.</li><li>Durable ctDNA Clearance was a Positive Predictor: Patients who achieved durable molecular clearance (negative ctDNA for at least 180 days) had 100% overall survival (OS) in the study.</li></ul>&#34;We are excited about these results showing how NeXT Personal can be used to monitor therapy in late-stage metastatic patients,&#34; said Rich Chen, M.D., M.S., Chief Medical Officer and Executive Vice President, R&amp;D at Personalis. “This study, together with our previous publications, shows the broad potential impact of ultrasensitive ctDNA testing, both in early and late stage cancers.”Dr. Rodrigo Toledo, Group Leader of the Biomarkers and Clonal Dynamics Laboratory at VHIO and senior author of the study, noted, &#34;immunotherapy has revolutionized cancer care, but response patterns can be difficult to interpret using imaging alone. Our findings show that ultrasensitive ctDNA dynamics provide a clear, early molecular view of benefit or non-response, offering a powerful tool to guide patient management across a broad spectrum of solid tumors.&#34;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 StatementsThis 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 of the NeXT Personal test and the potential impact or expected benefits of the VHIOstudy. 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 of the NeXT Personal test, including the NeXT Personal MRD assay remaining unique in its ability to detect traces of cancer in the ultra-sensitive range; future clinical data differing from the clinical data previously presented or expected results; the rate of adoption and use of the NeXT Personal test; changes in health care policy 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; 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, 2024, filed with the Securities and Exchange Commission (SEC) on February 27, 2025 and subsequent Quarterly Reports on Form 10-Q, including the Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, filed with the SEC on November 4, 2025. 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.<img src="https://imageproxy.pbkrs.com/https://cts.businesswire.com/ct/CT/query-ZGlzdHJvPW54JmlkPWJ3bmV3cyZsYW5nPWVuJnNpZD1hY3FyOCZzdHk9MjAyNTEyMTc1OTk3NjdyMQ?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" original-src="https://imageproxy.pbkrs.com/https://cts.businesswire.com/ct/CT/query-ZGlzdHJvPW54JmlkPWJ3bmV3cyZsYW5nPWVuJnNpZD1hY3FyOCZzdHk9MjAyNTEyMTc1OTk3NjdyMQ"/>View source version on businesswire.com: https://www.businesswire.com/news/home/20251217599767/en/Investor Relations: Caroline Corner investors@personalis.com 415-202-5678Media Contact pr@personalis.comSource: Personalis, Inc.</article></div>

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Personalis, Inc. announced a study published in Clinical Cancer Research demonstrating the effectiveness of their NeXT Personal® test in predicting patient outcomes across various cancers treated with immunotherapy. The study, conducted by VHIO, analyzed 202 patients with stage IV solid tumors and found high sensitivity in ctDNA detection and significant prognostic value in early ctDNA dynamics. The test showed 100% overall survival for patients with durable ctDNA clearance. This highlights the potential of ultrasensitive ctDNA testing in cancer management.

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Personalis Announces New Publication Applying Ultrasensitive ctDNA Testing to Monitoring Cancer Immunotherapy Response Across Solid Tumors | PSNL Stock News