On October 12, 2020 Castle Biosciences, Inc. (Nasdaq: CSTL), a skin cancer diagnostics company providing personalized genomic information to improve cancer treatment decisions, reported that its data were featured in two oral presentations during the 2020 American Society for Dermatologic Surgery (ASDS) Virtual Annual Meeting, Oct. 9-11, 2020 (Press release, Castle Biosciences, OCT 12, 2020, View Source [SID1234568341]).

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DecisionDx-Melanoma: Skin Cancer and Reconstruction Session; Friday, October 9, 2020

"Cutaneous Melanoma Prognostic Model Combining 31-gene Expression Profile and Sentinel Lymph Node Biopsy" was presented by Aaron Farberg, M.D., Baylor University Medical Center, Dallas, Texas.

DecisionDx-Melanoma is a gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous melanoma metastasis or recurrence, as well as sentinel lymph node positivity, independent of traditional staging factors.

"As most sentinel lymph node biopsies are negative, there is a need to identify which melanoma patients can forgo sentinel lymph node biopsy (SNLB)," said Dr. Farberg. "Based on the cohort described in a recent meta-analysis by Greenhaw and colleagues, we modeled the use of Castle’s DecisionDx-Melanoma test to determine whether it might alter the predictive value of SLNB alone in high-risk patients, and whether the test might identify patients who would not benefit from SLNB. In fact, we found that use of the test stratifies risk in the cohort studied, which can help focus the resources needed for SLNB on patients with genuinely higher risk, thereby reducing surgical risks for patients who can avoid SLNB."

Study methods and findings:

The study objective was to model the use of DecisionDx-Melanoma to triage cutaneous melanoma patients for SLNB, to evaluate the outcomes of low-risk patients who can forgo SLNB and to evaluate the combined accuracy of DecisionDx-Melanoma and SLNB in high-risk patients.
The model was based on use of DecisionDx-Melanoma to triage the patients from the recently published systematic review and meta-analysis (Greenhaw et al. JAAD, Sept., 2020), assuming that:
Patients with a Class 1A result who were 55 years of age or older with T1-T2 melanoma would not undergo SLNB;
The negative predictive value of DecisionDx-Melanoma for recurrence-free survival, distant metastasis free survival and ultimately melanoma specific survival would be high for patients who would not have undergone SLNB due to DecisionDx-Melanoma triage; and
The remaining patients would undergo SLNB.
Result showed that:
69% of all patients could forgo an SLNB due to a DecisionDx-Melanoma Class 1A test result, and the negative predictive value for 5-year melanoma specific survival was 98%.
For the remaining 31% of patients who would undergo an SLNB:
Sensitivity for melanoma specific death was 87% for DecisionDx-Melanoma compared with 73% for SLNB. Combining DecisionDx-Melanoma with SLNB improved sensitivity to 96%.
Negative predictive value for melanoma specific death was 95% for DecisionDx-Melanoma, compared with 94% for SLNB. Combining DecisionDx-Melanoma with SLNB improved negative predictive value to 98%.
The study concluded that use of DecisionDx-Melanoma to triage patients with a Class 1A result, who were at least 55 years old with T1-T2 melanoma, could have reduced SLNB procedures in that population by 69%. Use of DecisionDx-Melanoma for SLNB triage can focus the SLNB procedure on patient populations at higher risk for a positive sentinel lymph node, thereby reducing surgical risks and better utilizing healthcare resources.
DecisionDx-SCC: Skin Cancer and Reconstruction Session; Friday, October 9, 2020

"Clinical Validation and Incorporation of a Prognostic 40-gene Expression Profile Test into Clinicopathological Risk Assessment for Cutaneous Squamous Cell Carcinoma (cSCC)" was presented by Sherrif Ibrahim, M.D., Ph.D., associate professor, University of Rochester Medical Center.

DecisionDx-SCC is Castle’s prognostic gene expression profile test for patients diagnosed with high-risk cutaneous squamous cell carcinoma (SCC) that uses a patient’s tumor biology to predict individual risk of metastasis for patients with SCC and one or more risk factors.

"Managing cutaneous squamous cell carcinoma is challenging, and deaths from SCC are now estimated to exceed those from melanoma," said Dr. Ibrahim. "Current methods of metastatic risk assessment are limited by low positive predictive values. DecisionDx-SCC was designed to accurately classify SCC patients with one or more risk factors as high, moderate or low risk for metastasis (nodal and/or distant) within three years of diagnosis. Incorporating DecisionDx-SCC test results into patient risk assessments may lead to more personalized patient management and improved outcomes."

DecisionDx-SCC has been validated as an independent predictor of metastatic risk that can complement current risk-factor staging systems for patients with SCC and one or more clinicopathologic risk factors.

Validation study findings:

DecisionDx-SCC stratifies high-risk SCC patients into three classes based on metastasis risk: Class 1 (low risk), Class 2A (moderate risk) and Class 2B (high risk).
In multivariate analyses, DecisionDx-SCC demonstrated strong independent prognostic value relative to other significant risk factors, indicating its ability to better stratify patients. Similar hazard ratios (HRs) were observed for a Class 2A result (2.33; p=0.013), poor differentiation (2.29; p=0.011), and deep invasion (2.05; p=0.039), indicative of independent and additive metastatic risk associated with each factor. A DecisionDx-SCC Class 2B result was found to have the greatest independent prognostic value (HR, 6.86; p<0.001).
Patients with a DecisionDx-SCC Class 1 result (n=212; lowest-risk group) had a 3-year metastasis-free survival rate of 93.9%, which was significantly better than the metastasis-free survival rate for patients with a moderate-risk Class 2A result (80.5%; n=185) or highest-risk Class 2B result (47.8%; n=23) (p<0.0001).
About DecisionDx-Melanoma

DecisionDx-Melanoma is a gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous melanoma metastasis or recurrence, as well as sentinel lymph node positivity, independent of traditional staging factors, and has been studied in more than 5,700 patient samples. Using tissue from the primary melanoma, the test measures the expression of 31 genes. The test has been validated in four archival risk of recurrence studies of 901 patients and six prospective risk of recurrence studies including more than 1,600 patients. Prediction of the likelihood of sentinel lymph node positivity has also been validated in two prospective multicenter studies that included more than 3,000 patients. Impact on patient management plans for one of every two patients tested has been demonstrated in four multicenter and single-center studies including more than 560 patients. The consistent performance and accuracy demonstrated in these studies provides confidence in disease management plans that incorporate DecisionDx-Melanoma test results. Through June 30, 2020, DecisionDx-Melanoma has been ordered more than 59,900 times for use in patients with cutaneous melanoma.

More information about the test and disease can be found at www.SkinMelanoma.com.

About DecisionDx-SCC

DecisionDx-SCC is a 40-gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous squamous cell carcinoma metastasis for patients with one or more risk factors. The test result, in which patients are stratified into a Class 1, 2A or 2B risk category, predicts individual metastatic risk to inform risk-appropriate management.

Peer-reviewed publications have demonstrated that DecisionDx-SCC is an independent predictor of metastatic risk and that integrating DecisionDx-SCC with current prognostic methods can add positive predictive value to clinician decisions regarding staging and management.