Dermatology Conference Highlights Gene Expression Tests for Skin Cancer

Several companies presented findings at the American Academy of Dermatology’s annual meeting (Feb. 16-18, San Diego) indicating that gene expression profiling is making inroads in clinical dermatology practice for informing diagnosis and biopsy decisions for melanoma.

Adhesive Patch Enables Skin Cancer Gene Expression Profiling
DermTech (San Diego) markets a noninvasive dermatology gene expression platform that uses adhesive patches to collect epidermal skin samples, rather than a traditional scalpel-based biopsy. The samples are shipped overnight without the need for special storage or handling. DermTech has shown that RNA suitable for analysis can be extracted from the patches for up to 8 days after sample collection with storage at ambient conditions. The shelf life of the biopsy kits is 3 years.

The company’s Pigmented Lesion Assay (PLA) assesses gene expression consistent with melanoma, with results able to inform a clinician’s decision to biopsy the suspicious lesion. The PLA assay is intended for use on pigmented lesions that meet at least one of the ABCDE melanoma classification criteria. The PLA assay detects the presence or absence of expression for two oncogenic genes, PRAME and LINC00518, which are both known to be elevated in melanoma.

At the American Academy of Dermatology’s annual meeting DermTech presented several studies demonstrating the ability of noninvasive gene expression testing to differentiate melanoma from benign lesions. When assessing 103 histopathologically confirmed melanoma samples, PLA showed good accuracy with 97 percent reported as either PLA positive or mutation positive. Additionally, the assay was prospectively validated in 523 real-world PLA samples and accurately ruled out melanoma risk in pigmented lesions.

“The diagnosis of early-stage melanoma can be challenging histopathologically and has a discordance rate as high as 27 percent,” said DermTech collaborator and study author, Clay Cockerell, M.D., of Cockerell Dermatopathology in Texas, in a statement. “This study demonstrated that gene expression and mutation analyses can provide valuable objective information when assessing difficult pigmented lesions.”

Furthermore, DermTech assessed the potential cost savings of the PLA assay. The company said that the higher accuracy of the PLA versus use visual assessment and histopathology resulted in fewer unnecessary procedures and office visits, while “not compromising” melanoma detection.

Gene Expression Assay Informing Clinical Care
The use of a 31-gene expression profile test results in a change in the clinical management of melanoma patients in almost half of cases, according to a study presented at the American Academy of Dermatology’s annual meeting. Furthermore, the company reported that the changes in patient management were appropriate and remained within the context of established practice guidelines.

Castle Biosciences (Houston) conducted a multicenter, prospective clinical impact study that included 247 patients from 15 dermatology, medical oncology or surgical oncology centers. Clinical impact of the DecisionDx-Melanoma gene expression test was assessed by examining laboratory tests, imaging, frequency of clinical visits, adjuvant treatment discussion, and plans for referral to surgical or medical oncology before and after test use.

Overall, the company found that nearly three-quarter of the patients had a Class 1 (low-risk) result (73 percent), while just over one-quarter had a Class 2 (high-risk) result (27 percent). In total, 49 percent of patients tested experienced a change in clinical management recommendations following the receipt of the DecisionDx-Melanoma test. However, change in management varied by risk. Class 1 patients showed a 36 percent post-test change in management plans, while 85 percent of Class 2 patients had a change in management following the DecisionDx-Melanoma test.

The company’s found that 79 percent of management changes were “in a risk-appropriate direction.” For example, 91 percent of decreases in care documented were for low-risk patients, while 72 percent of increases in care were provided for high-risk patients. The most significantly changed management practices were follow-up frequency and imaging.

“Across the different practice settings in this study, the DecisionDx-Melanoma test informed risk-appropriate patient management decisions, consistent with previous publications demonstrating that the test impacts one in two clinical management decisions,” said Federico Monzon, M.D., Castle Biosciences’ chief medical officer, in a statement. “These findings align with national guidelines, which recommend that a patient’s individual risk of recurrence should drive management decisions.”

Takeaway: There is mounting evidence that gene expression profiling may be useful for evaluating potentially cancerous skin lesions.