PUBLICATIONS

Background:

Approximately 70%-85% of patients who undergo sentinel lymph node biopsy (SLNb) show no nodal metastasis in the sentinel node (SN). The clinicopathological and gene expression profile (CP-GEP) model (Merlin Assay) was developed and validated to identify patients that may forgo the SLNb surgery due to their low risk for for nodal metastasis This study was initiated during the first wave of Covid-19 pandemic to allow for surgical triage on SLNb and evaluate the implementation of the Merlin assay in clinical practice.

Methods:

This study was conducted in four designated melanoma centers in the Netherlands. Patients (age > 18y) with newly diagnosed melanoma of the skin, eligible to undergo SLNb were screened for study inclusion. Main exclusion criteria was prior history of primary melanoma ( > T1b) in the past 5 years. After enrollment, tissue sections of the primary melanoma were centrally reviewed at the Erasmus MC Cancer Institute to determine Breslow thickness at primary diagnosis. FFPE tumor tissue was dispatched for molecular analysis of eight target genes known to play a role in cancer development. In combination with age, Breslow thickness, and GEP outcome, risk of having nodal metastasis was calculated. Results were binary presented as ‘CP-GEP low risk’ and ‘CP-GEP high risk’. SLNb status was used as gold standard for comparison.

Results:

A total of 177 patients were analyzed using the CP-GEP model. Median age was 64 years (IQR 52-73) Median Breslow thickness was 1.4mm (IQR 1.0-2.4). Of all patients 28.2% was diagnosed with T1, 40.7% with T2 and 20.9% with T3 melanoma. Corresponding positivity rate was 7%, 14% and 29% respectively. A total of 24 out of 177 patients had a positive SLNb. Median turn-around time from inclusion to CP-GEP result was 15 days. Overall 37.1.% of patients had a CP-GEP low risk profile. The CP-GEP model had a NPV of 94.6%. Conclusions: This is the first prospective multicenter implementation study for the Merlin assay. Results are in line with previous validation studies. The CP-GEP model could accurately identify patients at low risk for SN metastasis. Implementation in clinical practice is feasible based on current turn-around time. In the future, using the Merlin assay to deselect patients for SLNB may allow for a reduction of surgery in patients with melanoma.

Background:

For patients with cutaneous melanoma, sentinel lymph node biopsy (SLNB) provides important staging and prognostic information that guides surveillance and adjuvant systemic therapy decisions. At most centers, SLNB is indicated for patients with cutaneous melanoma with at least a 5% risk of having nodal metastases, typically melanomas ≥ 0.8 mm in thickness or thinner lesions with high-risk features such as elevated mitotic rate and/or ulceration. SLNB, generally involving a separate incision, does carry a small but measurable risk of complications including seroma, infection and rarely lymphedema, and most patients have negative sentinel lymph nodes. Currently, there is an unmet clinical need to identify patients who may safely forgo SLNB due to a low (<5%) risk of nodal metastasis, who otherwise meet established criteria for SLNB. Previously, a model consisting of gene expression profile (GEP) of the primary tumor combined with clinicopathological features (CP) has been developed to identify melanoma patients with a low risk of having a positive SLNB. The model has also been validated in multiple retrospective studies. The aim of the MERLIN_001 registry study is to prospectively validate the CP-GEP model in an independent multicenter cohort of primary cutaneous melanoma patients who undergo SLNB for standard indications.

Methods:

In the next two years, a total of 10 centers across the US will enroll 2,340 patients with clinically node-negative cutaneous melanoma undergoing SLNB using current guideline indications and will follow these patients for 5 years (ClinicalTrials.gov identifier: NCT04759781). Enrollment of patients started in September 2021 and 242 patients have been enrolled as of February 1, 2022. FFPE material from the initial melanoma biopsy will be used to assess the GEP of the primary melanoma. The CP-GEP probability scores will be expressed as a binary classification (Low Risk or High Risk for nodal metastasis) and will be compared to SLN pathology. Performance metrics for CP-GEP will be evaluated and will include: Negative Predictive Value, Positive Predictive Value, Sensitivity and Specificity, and the corresponding 95% confidence intervals. Risk for nodal metastasis will be calculated for Low Risk and High Risk CP-GEP patients. Finally, the performance of CP-GEP to stratify patients according to risk of recurrence (local, regional, distant, death) will also be studied, since data will be collected for up to 5 yrs. Clinical trial information: NCT04759781.

Introduction 

Approximately 70%-85% of patients who undergo sentinel lymph node biopsy (SLNB) show no nodal metastasis in the sentinel node (SN). CP-GEP, a model that combines clinicopathologic and gene expression variables from the primary tumor was developed and validated to identify patients that may forgo the SLNB surgery due to their low risk for SN-metastasis. This study was initiated during the first wave of COVID-19 pandemic to allow for surgical triage on SLNB and evaluate the implementation of the CP-GEP model in clinical practice. 

Methods 

This study was conducted in four designated melanoma centers in the Netherlands. Patients (age>18y) with newly diagnosed melanoma of the skin, eligible to undergo SLNB were screened for study inclusion. Main exclusion criteria was prior history of primary melanoma (>T1b) in the past 5 years. After enrollment, tissue sections of the primary melanoma were evaluated to determine Breslow thickness at primary diagnosis. FFPE tumor tissue was dispatched for molecular analysis of eight target genes known to play a role in cancer development. In combination with age, Breslow thickness, and GEP outcome, risk of having SN-metastasis was calculated. Results were binary presented as ‘CP-GEP Low Risk’ and ‘CP-GEP High Risk’. SLNB status was used as gold standard for comparison. 

Results 

A total of 177 patients were analyzed using the CP-GEP model. Median age was 64 years (IQR 52-73) Median Breslow thickness was 1.4mm (IQR 1.0-2.4). Of all patients 28.2% was diagnosed with T1, 40.7% with T2 and 20.9% with T3 melanoma. Corresponding positivity rate was 7%, 14% and 29% respectively. A total of 24 out of 177 patients had a positive SLNB (13.6%). Median turn-around time from inclusion to CP-GEP result was 15 days. Overall 37.1.% of patients had a CP-GEP Low Risk outcome. The CP-GEP model had a NPV of 94.6%. 

Conclusion 

This is the first prospective multicenter implementation study for the CP-GEP model. Results are in line with previous validation studies. The CP-GEP model could accurately identify patients at low risk for SN metastasis. Implementation in clinical practice is feasible based on current turn-around time. In the future, using the CP-GEP model to deselect patients for SLNB may allow for a reduction of surgery in patients with melanoma. 

Abstract 

Nodal pathological assessment via sentinel lymph node biopsy (SLNB) is important for primary cutaneous melanoma risk-stratification. The prognosis of patients with minimal sentinel node (SN) tumor burden – defined by the Rotterdam Criteria as a tumor burden of 0.1 mm or less – can be diverse. Therefore, optimal treatment of patients with minimal SN tumor burden is subject of an ongoing debate. CP-GEP assesses the risk of SLNB metastasis at diagnosis. Specifically, CP-GEP considers patient age at diagnosis, Breslow thickness and expression of eight genes in the primary tumor. Combination of these variables results in either of two risk labels: CP-GEP Low Risk or High Risk. Previously, we also investigated prognostic performance of CP-GEP in four independent cohorts from the US, the Netherlands, and Sweden totaling 1684 patients, 79 of whom had minimal SN tumor burden. The proportion of patients with minimal SN tumor burden was comparable between cohorts, 3-5%. We found that patients with minimal SN tumor burden from Sweden had a relapse risk comparable to SLNB positive patients, whereas Dutch and American patients had a relapse risk comparable to SLNB negative patients. We speculate that this discrepancy is caused by differences in histopathologic workup of SN. Of the 79 patients with minimal SN tumor burden, we observed recurrences in 2/17 (11.8%) CP-GEP Low Risk patients versus 19/62 (30.6%) recurrences in CP-GEP High Risk patients at a median follow-up time of 5.6 years. Further analysis of CP-GEP in larger cohorts is required to confirm observed trends. 

Background

Approximately 85% of melanoma patients who undergo a sentinel lymph node biopsy (SLNB) are node-negative. Melanoma incidence is highest in patients ≥65 years, but their SLNB positivity rate is lower than in younger patients. CP-GEP, a model combining clinicopathologic and gene expression variables, identifies primary cutaneous melanoma (CM) patients who may safely forgo SLNB due to their low risk for nodal metastasis. Here, we validate CP-GEP in a U.S. melanoma patient cohort.

Methods

A cohort of 208 adult patients with primary CM from the Mayo Clinic and West Virginia University was used. Patients were stratified according to their risk for nodal metastasis: CP-GEP High Risk and CP-GEP Low Risk. The main performance measures were SLNB reduction rate (RR) and negative predictive value (NPV).

Results

SLNB positivity rate for the entire cohort was 21%. Most patients had a T1b (34%) or T2a (31%) melanoma. In the T1-T2 group (153 patients), CP-GEP achieved an SLNB

RR of 41.8% (95% CI: 33.9-50.1) at an NPV of 93.8% (95% CI: 84.8-98.3). Subgroup analysis showed similar performance in T1-T2 patients ≥65 years of age (51 patients;

SLNB positivity rate, 9.8%): SLNB RR of 43.1% (95% CI: 29.3-57.8) at an NPV of 95.5% (95% CI: 77.2-99.9).

Conclusion

We confirmed the potential of CP-GEP to reduce negative SLNB in all relevant age groups. Our findings are especially relevant to patients ≥65 years, where surgery is often elective. CP-GEP may guide SLNB decision-making in clinical practice.

Background

For patients with primary cutaneous melanoma, sentinel lymph node biopsy (SLNB) is an important technique to assess disease stage and to guide adjuvant systemic therapy1. Around 80-85% of all SLNB procedures do not detect nodal metastasis. A model using clinicopathologic and gene expression variables (CP-GEP; Merlin Assay) has been introduced to identify patients that may safely forgo SLNB2 due to their low risk for nodal metastasis. CP-GEP combines Breslow thickness and patient age with the expression of eight genes to classify patients as High Risk or Low Risk for nodal metastasis.

Purpose

The aim was to independently validate the Merlin Assay in a population-based retrospective cohort.

Method

421 FFPE primary melanomas were analyzed for CPGEP which classified patients into Low risk and High risk for nodal metastasis. CP-GEP risk labels were compared to the known SLNB status.

Results

The median age was 60 years and 49% of the patients were females. Of the 421 patients, 335 patients (80%) were classified as CP-GEP High Risk and 86 (20%) as CP-GEP Low Risk for nodal metastasis. The overall SLNB positivity was 13%. Of the 86 CP-GEP Low Risk patients, CP-GEP could correctly identify 83 (96.5%) patients who were SLNB negative. For patients with T1-T2 tumors, the negative predictive value (NPV) was 96.5% and the SLNB reduction rate was 35.4%. For patients with T1-T3 tumors, the NPV was 96.5% and the SLNB reduction rate was 24.0%. All T4 tumors were classified as CP-GEP High Risk for nodal metastasis.

Conclusion

The CP-GEP model has been independently validated in a European retrospective patient cohort, and can be used to identify patients who may safely forgo SLNB procedure due to their low risk for nodal metastasis.

Background

In light of the current COVID-19 pandemic, avoiding unnecessary interventions and keeping patients out of the hospital becomes increasingly important. The CP-GEP model (Merlin Assay) has been developed and validated to identify patients with primary melanoma (pT1 b-pT3) that can safely forgo the sentinel lymph node biopsy (SLNB) due to their low risk for nodal metastasis. During the current pandemic, a prospective trial was conducted to assess the accuracy of using the CPGEP model to identify patients that have a low risk for nodal metastasis and therefore could forgo the SLNB.

Methods

During the COVID-19 pandemic, from July 2020 to February 2021, all newly diagnosed cutaneous melanoma (pT1 b-pT3) patients elected to undergo SLNB at the Erasmus MC Cancer Institute were included. Formalin-fixed paraffin embedded tissue (FFPE) from the primary melanoma tissue was analyzed using CP-GEP. The CP-GEP model combines patient age and Breslow thickness with the expression of eight target genes. Patients were classified as CP-GEP High Risk or CP-GEP Low Risk for having nodal metastasis.

Results

From all eligible patients (n=19), consent was obtained and FFPEs could be retrieved for further analysis. Patients had a median age of 53 years (interquartile range [IQR] 37 – 67) and median Breslow thickness was 2.0 mm (IQR 1,4-2.8). In two out of 19 patients, the surgeon determined preoperatively not to proceed with SLNB (as a result of locally advanced melanoma). Of the remaining 17 patients, five had a positive SLNB (e.g. nodal metastasis, 29.4% ). All SLNB positive patients (n=5) were identified by CP-GEP as being High Risk for nodal metastasis. Of all SLNB negative patients (n=12), CP-GEP identified five patients (41. 7%) as being Low Risk for nodal metastasis. Overall, the potential SLNB reduction rate in this cohort was 29.4% while having a negative predictive value of 100%.

Conclusions

The CP-GEP (Merlin Assay) model is a non-invasive and validated tool that can be used to identify patients with a primary cutaneous melanoma (pT1 b-pT3) who are at low risk for nodal metastasis and therefore could safely forgo SLNB. Also, during the current COVID-19 pandemic, the CP-GEP model could be a promising tool to deselect patients for elective surgery (Figure).

Abstract

The management of primary cutaneous melanoma (PCM) faces new challenges during the COVID-19 pandemic. National guidelines aiming to optimize medical resource usage have led to delays in elective surgical procedures such as the sentinel lymph node (SLN) biopsy, which causes stress and anxiety in patients. We recently reported on the development of a model which combines clinicopathologic variables and a gene expression profile (CP-GEP) to identify patients who may safely forgo SLN biopsy due to their low risk of nodal metastasis. The CP-GEP model combines Breslow thickness and patient age with the expression of eight genes in diagnostic biopsy tissue. Here, we report on the feasibility of running the CP-GEP model – which we refer to as the Merlin Assay – in an independent Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory accredited by the College of American Pathologists (CAP). 50 micron recuts of T1 to T3 diagnostic biopsy tissue were requested from 50 PCM patients who were seen in the fall of 2019. Turnaround time from sample receipt at the laboratory to test reporting was within five working days. 3/50 samples (6%) did not contain sufficient RNA for molecular analysis; 47/50 samples (94%) were tested successfully. Of the 47 patients with Merlin test results, 34/47 (72.3%) underwent SLN biopsy. Of the 34 patients with known SLN status, 13/34 (38.2%) were T1, 13/34 (38.2%) were T2 and 8/34 (23.6%) were T3 patients. 1 of 13 (7.7%) T1, 4 of 13 (30.1%) T2 and 1 of 8 (12.5%) T3 patients were SLN positive. All SLN positive patients were correctly classified as high risk by the Merlin Assay. We conclude that the implementation of the Merlin Assay in clinical practice is feasible as a send-out test and may be used for deselecting low risk PCM patients for SLN biopsy during the ongoing COVID-19 pandemic.

Background:

The sentinel lymph node biopsy (SLNB) procedure has gained importance now that primary cutaneous melanoma (PCM) patients with a positive sentinel lymph node are considered candidates for adjuvant systemic therapy. However, SLNB is an invasive procedure, and approximately 80% of patients lack nodal metastasis. Many SLNB negative patients are exposed to invasive surgery but enjoy no discernible therapeutic benefit. Therefore, there is a need for a non-invasive test to accurately identify PCM patients who may forgo the SLNB procedure due to low risk of nodal metastasis. Previously, a clinicopathological and gene expression profile model (CPGEP model) has been developed to identify PCM patients who can safely forgo SLNB. Moreover, a validation of the CP-GEP model in a European cohort has been reported. Here, we describe the validation of the CP-GEP model in a US cohort.

Methods:

We identified 162 patients who underwent SLNB at the Mayo Clinic or West Virginia University within 90 days of PCM diagnosis. Formalin-fixed paraffin embedded diagnostic PCM biopsy tissue from all patients were analyzed using the CPGEP model. The CP-GEP model combines Breslow thickness and patient age with the expression of eight genes to classify patients as CP-GEP High Risk or CP-GEP Low Risk for nodal metastasis.

Results:

At diagnosis, the median patient age was 56 years (IQR, 41 to 69 years) and the median Breslow thickness was 1.9 mm (IQR, 0.9 to 2.1 mm). 62 of 162 patients {38.2%) presented with Tl melanoma while 58 of 162 patients (35.8%) presented with T2 melanoma. Overall, 19.8% of patients had a positive sentinel lymph node. In patients with stage Tl to T2 melanoma, the CP-GEP model achieved an SLNB reduction rate of 44.2% at a negative predictive value of 98.1%.

Conclusions:

The CP-GEP model is a non-invasive and validated tool that is able to predict nodal metastasis in an US cohort that can be used to identify PCM patients who can safely forego SLNB. The CP-GEP model is a promising tool for patient care, preventing unnecessary surgery in a large group of patients.

Purpose

Greater than 80% of melanoma patients who undergo sentinel lymph node (SLN) biopsy are SLN negative. Our objective was to use molecular markers crucial in the reciprocal and bidirectional interaction between integrins and the tumor microenvironment to distinguish between high-risk patients and patients who can safely forego SLN biopsy. 

Patients and Methods 

Genes with functional roles in melanoma metastasis were discovered by analysis of next-generation sequencing data, case-control studies, analysis of publicly available genomic datasets and a review of the cancer literature. Of 192 candidate biomarkers discovered, 108 were quantified by quantitative PCR in a cohort of 754 consecutive thin and intermediate-thickness melanomas. Outcome of interest was SLN metastasis within 90 days of melanoma diagnosis. Logistic regression with LASSO regularization was applied to clinicopathologic variables and molecular data in a cross-validation training-validation scheme. Three models were built using: only clinicopathologic features (CP); only gene expression profiling (GEP); and both clinicopathologic and gene expression profiling (CP-GEP). 

Results 

128/754 patients (17%) were SLN positive. Expression of genes with roles in extracellular matrix remodeling (glia-derived nexin, growth differentiation factor 15, integrin β3, interleukin 8, lysyl oxidase homolog 4, TGFβ receptor type 1 and tissue-type plasminogen activator) and melanosome function (antigen recognized by T-cells) were associated with SLN metastasis. The predictive ability of a model that only considered CP or GEP variables was outperformed by a model which included molecular variables in combination with the clinicopathologic predictors Breslow depth and patient age. CP-GEP achieved a SLN biopsy reduction rate of 80% for clinical stage T1b melanoma with an NPV >95% across all T stages. 

Conclusion 

A combined model including clinicopathologic and gene expression variables improved the identification of melanoma patients who can safely forgo SLN biopsy due to their less than 5% risk of nodal metastasis.