Personalis Announces New Publication Expanding Evidence for Ultrasensitive ctDNA Monitoring of Cancer Immunotherapy Response Across Solid Tumors

Key Terms

ctdna medical

Circulating tumor DNA (ctDNA) is tiny fragments of genetic material shed by cancer cells into the bloodstream, like breadcrumbs that can reveal a tumor’s presence and genetic makeup without needing a biopsy. For investors, ctDNA matters because tests and technologies that detect and analyze these fragments can speed diagnosis, track treatment response, and signal relapse, creating commercial opportunities in diagnostics, personalized therapies, and monitoring services.

molecular residual disease (mrd) medical

Molecular residual disease (MRD) is the tiny number of cancer cells that remain in a patient after treatment, detected by highly sensitive genetic or molecular tests that can find one cancer cell among thousands or millions of normal cells. MRD matters to investors because it helps predict the chance of relapse and influences whether additional treatment is given; MRD signals are increasingly used as early clinical trial or regulatory endpoints, so positive or negative MRD results can materially affect the market value of diagnostics and therapies—similar to an early warning that shapes future decisions.

immune checkpoint inhibitors medical

Drugs that release the immune system’s natural “brakes,” allowing immune cells to recognize and attack cancer cells; imagine taking the safety off a guard dog so it can chase intruders. They matter to investors because they can become high-value treatments with large sales potential, but their commercial success depends on clinical trial results, regulatory approval, competition and side-effect management, which all affect a company’s valuation.

progression-free survival medical

Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

overall survival medical

Overall survival is the average or median length of time patients remain alive after starting a treatment or entering a clinical study, measured regardless of cause of death. Investors care because it is a clear, hard measure of a therapy’s real-world benefit — like timing how long a new battery actually runs — and strong improvements in overall survival can drive regulatory approval, market adoption and revenue potential.

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 npj Precision Oncology highlighting the power of its ultrasensitive molecular residual disease (MRD) assay, NeXT Personal®, in monitoring immunotherapy response across a broad range of advanced cancers.

The study, titled "Ultrasensitive ctDNA monitoring reveals early predictors of immunotherapy response in advanced cancer," was led by oncology researchers at UC San Diego Moores Cancer Center.

The findings reinforce the NeXT Personal test’s ability to detect circulating tumor DNA (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.

While immunotherapy has transformed cancer care, only ~10-40% of patients achieve durable benefit, making it critical to monitor how patients are responding to therapy. This interim analysis of the ongoing study includes 39 patients with advanced solid tumors—across nine different cancer types—treated with immune checkpoint inhibitors alone or in combination with other therapies. Key findings include:

• Early identification of therapy response: Molecular response—defined by ctDNA dynamics—was detectable early, a median of 23 days after starting immunotherapy. Patients achieving an early molecular response had significantly longer progression-free survival.
• Lead time over imaging: For patients whose disease progressed, NeXT Personal identified molecular progression a median of 161 days (over five months) before imaging.
• Criticality of the ultrasensitive range in advanced tumors: The study found that even in advanced tumors where ctDNA shedding can be higher, 33% of positive ctDNA detections occurred in the ultrasensitive range (below 100 PPM). These are detections that could be missed with a less sensitive test.
• Strong correlation with outcomes: Patients who achieved molecular complete response (ctDNA clearance) had seven times higher overall survival than patients who did not achieve ctDNA clearance.

"We continue to expand the clinical evidence that NeXT Personal can be used to monitor therapy response in advanced cancer patients on immunotherapy," said Richard Chen, M.D., M.S., Chief Medical Officer and Executive Vice President of R&D at Personalis. “This pan-cancer study builds on our recent publication in Clinical Cancer Research, similarly showing the impact of ultrasensitive ctDNA testing in late-stage cancers. With immunotherapy, an important pillar of cancer treatment in advanced cancer patients, the need for better tools to evaluate patient response is increasingly important. These findings show how NeXT Personal and ultrasensitive ctDNA testing can potentially play an important role in impacting care across a broad spectrum of solid tumors."

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 of the NeXT Personal test and the potential impact or expected benefits of the UCSD 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 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 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, 2024, filed with the Securities and Exchange Commission (SEC) on February 27, 2025 as updated by Personalis’ 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.

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Source: Personalis, Inc.