Merlin CP-GEP™ Demonstrates Superior Predictive Accuracy for Sentinel Lymph Node Metastasis in Early-Stage Melanoma

• Peer-reviewed publication confirms Merlin CP-GEP¹ identifies a subset of T1a patients with SLN positivity above guideline thresholds
• Two Independent validations at Leading Academic Centers reported no high-risk T1a classifications in an Alternative GEP test

SAN DIEGO and ROTTERDAM, Netherlands, March 25, 2026 /PRNewswire/ -- SkylineDx today announced the publication of new data by Dr. Wesley Yu, et al ²., demonstrating that Merlin CP-GEP identifies a clinically meaningful High-Risk subset of T1a melanoma patients with a risk of sentinel lymph node (SLN) positivity above established NCCN guideline thresholds. Merlin CP-GEP is a gene expression profile test recognized by the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) as predictive of SLN positivity risk, supported by validation in the largest, prospective, blinded, gene expression profile study in melanoma.

Merlin CP-GEP was developed with tumor biology in mind. The assay integrates eight biologically selected genes associated with metastatic pathways, originally identified and developed in collaboration with investigators at Mayo Clinic. This biology-driven foundation was designed to detect metastatic potential rather than simply correlate with stage.

In the newly published analysis, this same metastatic biology was shown to identify high-risk tumors within the T1a population. Merlin CP-GEP identified T1a patients whose SLN positivity risk exceeded commonly accepted biopsy thresholds, enabling actionable risk stratification in a group traditionally considered low risk. Similar biologic heterogeneity was observed in the prospective MERLIN_001 trial, where a small T1a cohort also demonstrated identification of higher-risk patients. These findings align with the data that informed the recent guideline update recognizing Merlin CP-GEP as the only predictive genomic test used to guide SLNB decisions. The National Comprehensive Cancer Network® (NCCN®) has updated its Clinical Practice Guidelines in Oncology for Cutaneous Melanoma (Version 1.2026), recognizing the CP-GEP (Merlin CP-GEP¹) test may be used to support metastatic risk assessment in T1b and T2a melanoma patients, a clinically important population in which accurate assessment of metastatic potential is critical for guiding management. Of note, the NCCN Guidelines ® differentiate Merlin CP-GEP from other gene expression profile assays, stating that alternative tests are not recommended for SLNB risk prediction outside of clinical trials.

Compared to the MIA nomogram (5% threshold), CP-GEP demonstrated superior specificity (72.0% vs. 23.7%) while maintaining a negative predictive value greater than 98%.² These results further demonstrate that Merlin CP-GEP outperforms traditional clinicopathologic risk assessment methods, providing clinicians with a more precise tool to evaluate metastatic potential and support informed, shared decision-making regarding sentinel lymph node biopsy.²

The authors concluded:
 "CP-GEP identified a subset of T1a patients with SLN positivity above guideline thresholds (>10%), enabling actionable risk stratification."

A high-risk Merlin CP-GEP result may serve as an additional adverse feature when considering SLNB in T1a melanoma. CP-GEP (Merlin CP-GEP) is now recognized by the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) as a predictive GEP test that may be used in select cutaneous melanoma patients to assess metastatic risk. As demonstrated in the Merlin_001 trial, a patient identified as high risk by CP-GEP (Merlin CP-GEP) may have approximately a threefold increased likelihood of sentinel lymph node positivity.

Independent Competitor Evaluations in T1a Patients

Two independent publications ⁴ ⁵ evaluating a proprietary 31-gene expression profile assay, (Castle Biosciences), in exclusively T1a melanoma populations reported no high-risk classifications.

Across 506 total AJCC pT1a patients from two major academic centers:

• 250 patients from UPMC (2015–2023)
• 256 patients from Case Western (2019–2024)

100% of T1a tumors in both cohorts were classified as Class 1A (lowest risk).

As reported by the authors in one study:
 "In our cohort, 100% of 256 pT1a tumors were GEP-31-Class 1A."

They further concluded:
 "Our findings do not support 31-GEP testing in this group."

The purpose of molecular testing in thin melanoma is to identify tumors at higher risk than predicted by AJCC criteria — patients who might proceed to SLNB or receive more intensive monitoring. In these two independent analyses ⁴ ⁵, the 31-GEP assay did not classify any patients as high-risk, so these findings raise important questions regarding clinical utility. Merlin CP-GEP identified 18% of T1a patients as being high-risk in this recent publication². Notably, the current CMS/Medicare reimbursement rate for 31-GEP exceeds $7,000 per test, further underscoring the importance of demonstrating clear clinical value.

Addressing an Unmet Clinical Need in Early-Stage Melanoma

More than 50% of melanoma deaths in the United States arise from early-stage disease ⁶. At the same time, a substantial proportion of T1a patients with adverse biologic features may not undergo SLNB under current practice patterns. Merlin CP-GEP integrates clinicopathologic factors with gene expression profiling to deliver both predictive assessment of SLN positivity risk and prognostic assessment of long-term metastatic risk.

By identifying biologically aggressive T1a tumors that exceed guideline SLNB thresholds, Merlin CP-GEP provides clinicians with additional clarity when deciding whether to recommend SLNB.

About the Merlin CP-GEP

Merlin CP-GEP is a non-invasive prediction model for cutaneous melanoma patients and is the only commercially available GEP test that combines clinicopathologic (CP) variables with gene expression profiling (GEP) into a single integrated algorithm. In addition, it is the only GEP test that provides binary stratification of all patients into High or Low Risk for metastasis, allowing clinicians to assign patients to the appropriate surgical action categories as listed in evidence-based cancer treatment, prevention, and screening guidelines. The advanced CP-GEP model was developed by Mayo Clinic and SkylineDx and is the latest commercially launched GEP test, which has been clinically validated in multiple studies on a global basis. The test has been launched in the United States and Europe as Merlin. SkylineDx collaborates with diagnostic service providers globally to bring this test to market and increase patient access. More information (including references) may be obtained at www.merlinmelanomatest.com.

About SkylineDx

SkylineDx is a biotechnology company focused on research and development of molecular diagnostics in oncology, and inflammatory and infectious diseases. SkylineDx uses its expertise to bridge the gap between academically discovered gene expression signatures and commercially available diagnostic products with high clinical utility, assisting healthcare professionals in accurately determining the type or status of disease or predicting a patient's response to treatment. Based on test results, healthcare professionals can tailor the treatment approach to the individual patient. Headquartered in Rotterdam, the Netherlands, SkylineDx maintains a strong U.S. presence with a CAP/CLIA certified laboratory in San Diego, California, and a nationwide commercial service organization that ensures full operational support across the U.S. market. To learn more about SkylineDx, please visit www.skylinedx.com.

Footnotes

⁽¹⁾  Merlin CP-GEP is marketed in the USA as an LDT. In the EU EEA and UK, it is marketed under the name Merlin Assay, a CE-IVD and UKCA marked device.
⁽²⁾  Yu WY, et al. CP-GEP Identifies High-Risk T1a Melanoma Patients Beyond Established Adverse Features JAAD October 2025, doi.org/10.1016/j.jaad.2025.10.036
⁽³⁾  Hieken TJ, et al. MERLIN_001: Gene Expression Profile–Based Test to Predict Melanoma Sentinel Node Status The MERLIN_001 Study October 22, 2025 doi: 10.1001 jamasurg.2025.4399
⁽⁴⁾  Somach S, et al. Correlation of AJCC pT1a melanomas (low risk, <0.8 mm) with 31-gene expression profile melanoma testing in a single dermatopathology laboratory cohort: Potential impact on detecting high risk thin tumors. JAAD. October 2025 doi.org/10.1016/j.jaad.2025.06.031
⁽⁵⁾  Tsang M, et al. Characterizing the Use of a Commercial 31-Gene Expression Profile Test for Melanoma Risk Stratification at a Large Referral Center from 2015 – 2023 UPMC Poster (246), The American Society of Dermatopathology, Nov. 2024
⁽⁶⁾  Landow S.M. et al. Mortality burden and prognosis of thin melanomas overall and by subcategory of thickness, SEER registry data, 1992-2013. J Am Acad Dermatol. 2017; 76: 258-263

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