DermTech’s study results demonstrated that in patients with Fitzpatrick skin types IV-VI, all 3 melanomas diagnosed by histopathology were correctly identified by the 2-GEP assay as positive for LINC00518 and PRAME.
Last week, DermTech presented its poster, “Non-invasive Gene Expression Analysis Rules Out Melanoma With High Negative Predictive Value Regardless of Skin Phototype,” at the 2024 Winter Clinical Hawaii Dermatology Conference. The study analyzed the ability of DermTech’s 2-gene expression profiling (GEP) assay to detect the expression of LINC00518 and PRAME as a non-invasive assessment of clinically atypical, pigmented skin lesions to rule out melanoma with a negative predictive value (NPV) of 99%.
The study results demonstrated that in patients with Fitzpatrick skin types (FST) IV-VI, all 3 melanomas diagnosed by histopathology were correctly identified by the 2-GEP assay as positive for LINC00518 and PRAME. The performance of the 2-GEP assay in patients with FST IV-VI did not differ in patients with FST I-III. According to the data, sensitivity and specificity were 90% or higher in both groups, and most importantly to the authors, the NPV for each group was greater than 99%.
Study author Maral Kibarian Skelsey, MD, board-certified dermatologist, director of the Dermatologic Surgery Center of Washington, and clinical professor at Georgetown University in Washington, DC, exclusively spoke to Dermatology Times to discuss the real-world implications of the study’s findings for dermatology clinicians.
Maral Kibarian Skelsey, MD: My name is Maral Kibarian Skelsey. I'm the director of the Dermatologic Surgery Center of Washington and clinical professor at Georgetown University in Washington, DC
Dermatology Times: Can you please provide a brief background on DermTech’s 2-GEP Assay poster presented at Winter Clinical Hawaii 2024?
Skelsey: The use of the gene expression profile for the rule-out test for melanoma has a negative predictive value of 99% and has been used in hundreds of 1000s of patients. Neither race nor ethnicity is a confounding factor in the use of these biomarkers, neither in molecular technology, nor in dermatopathology. However, the preponderance of the specimens has been in Fitzpatrick skin types I-III because both melanoma and pigmented lesions occur more commonly in this population. Non-acral melanoma in Fitzpatrick skin types IV-VI is rarer, but it does occur. So, the impetus for the study was our curiosity about the performance of the test in a variety of skin types—specifically looking at Fitzpatrick IV-VI.
Dermatology Times: In your opinion, how significant is a 99% negative predictive value in ruling out melanoma for non-invasive assessments?
Skelsey: It is very significant. For a rule-out test the most important metric is considered to be negative predictive value because the test is used to defer an intervention, usually a biopsy.
Dermatology Times: In your experience, how often do you or other dermatology clinicians encounter situations where a visual examination cannot rule out melanoma alone, and additional testing is needed, such as the 2-GEP Assay?
Skelsey: In my practice, we've used it more than 5000 times over the past several years. Where the test has an important role, is not for the lesions that are clearly benign or malignant. We know what to do for those. But there are a significant number of lesions that with visual inspection and dermoscopy, alone, it’s still not clear whether we should biopsy. We're using the test because with a negative predictive value of more than 99%, it's more accurate than visual inspection, it's more accurate than dermoscopy. It is very helpful for us in terms of determining whether or not we're going to biopsy, rather than just watch a lesion, which is what we did with a lot of these in the past.
Dermatology Times: How closely do the real-world results in your practice align with the study findings on sensitivity, specificity, and the negative predictive value?
Skelsey: These data that we presented align very closely with what we have found in our practice, In the more than 5000 times we’ve used it, we have found very high sensitivity and a high negative predictive value, which is what we want to see for a rule-out test. We want to know that if we're going to not biopsy a patient, it is highly unlikely the patient is going to walk out with an undetected melanoma.
Dermatology Times: What comes next in terms of encouraging more dermatology clinicians to use DermTech’s 2-GEP Assay?
Skelsey: Patients appreciate it being non-invasive, painless, with an easy-to-understand, binary result. It’s a real plus as well for patients reluctant to undergo biopsies in cosmetically sensitive or difficult-to-buy areas as well as for those whose comorbidities increase the risk of a surgical procedure. My patients who have been biopsied multiple times and dread an unnecessary test are really grateful to have this option. For clinicians, it’s quick to perform, with fast, actionable results. The test has significantly enhanced my ability to detect melanoma at its earliest stages and has improved patient care. For me, it would be difficult to justify just watching a lesion without doing the test when this technology is readily accessible. I don’t think there is a practice that wouldn't benefit from using it.
[Transcript lightly edited for space and clarity]
Skelsey M, Lofitis B, Kaufmann M, et al. Non-invasive gene expression analysis rules out melanoma with high negative predictive value regardless of skin phototype. Poster presented at: 2024 Winter Clinical Hawaii Dermatology Conference; January 12-17, 2024; Honolulu, HI.