On October 5, 2026 Guardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, reported Cancer Research Communications, a journal of the American Association for Cancer Research (AACR) (Free AACR Whitepaper), has published results from the COSMOS-MEL01 study (UMIN000042040). The study is the first published prospective, multicenter evaluation of the tissue-free, epigenomic Guardant Reveal blood test for molecular residual disease (MRD) detection and recurrence monitoring in patients with resected stage II–III melanoma.

Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:

Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing

                  Schedule Your 30 min Free Demo!

The COSMOS (COnquer Solid Malignancies by blOod Screening) program is a large prospective initiative evaluating MRD detection with the Guardant Reveal test across six cancer types. This report presents findings from COSMOS-MEL01, in which 280 longitudinal surveillance samples from 48 patients with clinical stage II–III melanoma treated with surgery were analyzed. The study found that detection of circulating tumor DNA (ctDNA) following surgery was strongly associated with recurrence and melanoma-related death. During longitudinal surveillance, Guardant Reveal detected 81% of distant recurrences, with 100% specificity in post-treatment samples from patients who remained recurrence-free. ctDNA detection preceded clinical identification of recurrence by a median of 70.5 days. These findings support the use of Guardant Reveal as a rapid, noninvasive approach for earlier identification of patients at high risk for recurrence, enabling refined treatment and surveillance strategies.

"Patients with resected, high-risk melanoma need more precise tools to assess how their risk changes after surgery and throughout surveillance," said Yoshiaki Nakamura, M.D., Ph.D., former Chief, International Research Promotion Office at National Cancer Center Hospital East in Chiba, Japan, and a co-lead author of the study. "These results show that ctDNA detection using a tissue-free assay was associated with a substantially increased risk of recurrence and melanoma-related death and often preceded clinical detection of disease. Fast, broadly accessible testing would be valuable in helping to inform therapy for patients with substantially higher risk of melanoma recurrence and poorer survival than those who remained ctDNA-negative."

"Predicting melanoma recurrence after surgery remains difficult at the individual-patient level, and conventional clinicopathologic staging provides only a static estimate of risk," said Kenjiro Namikawa, M.D., Ph.D., Chief, Department of Dermatologic Oncology at National Cancer Center Hospital in Tokyo, Japan. "Our findings suggest that serial ctDNA testing may provide a dynamic view of recurrence risk and potentially complement routine imaging, particularly in identifying patients at increased risk of distant relapse. Further studies will be important to determine whether and how ctDNA results could be incorporated into postoperative treatment and surveillance decisions."

Key study findings include:

100% specificity in samples from patients without recurrence
81% longitudinal sensitivity for distant recurrence detection
Up to 273-day lead from ctDNA detection to recurrence
"COSMOS-MEL01 extends the growing body of evidence supporting Guardant Reveal into melanoma and demonstrates the power of epigenomic MRD detection across a diverse set of melanoma subtypes," said Helmy Eltoukhy, Guardant Health chairman and co-CEO. "The ability to identify patients at very high risk shortly after surgery, and to detect molecular recurrence before it appears clinically, could help inform more personalized surveillance and clinical trial strategies. These findings also illustrate the advantages of a tissue-free approach that can deliver molecular insights without the logistical complexity of obtaining and analyzing a tumor specimen."

The incidence of melanoma is steadily rising, with annual cases projected to increase by more than 50% between 2020 and 2040. The COSMOS study provides strong evidence for the use of Guardant Reveal to improve recurrence risk stratification to inform management decisions for this significantly large patient population.

The study was published today at 10 a.m. EDT in Cancer Research Communications.

About Guardant Reveal

Guardant Reveal is a tissue-free liquid biopsy test that detects MRD and monitors recurrence in early-stage colorectal, breast, and lung cancers, helping oncologists guide treatment decisions. In addition to MRD detection, Reveal can be used for late-stage therapy response monitoring for patients with solid tumors. Guardant Reveal therapy response monitoring can be initiated at any time during a patient’s treatment journey, offering clinicians flexibility and actionable insights.

The first clinical-validation study of pan-cancer chemotherapy monitoring published in The Journal of Liquid Biopsy showed that Guardant Reveal predicts long-term patient benefit up to 18 months earlier than standard clinical measures.

(Press release, Guardant Health, OCT 5, 2026, View Source [SID1234673197])