Benzinga | Apr 23, 2021 07:03AM EDT

Castle Biosciences To Present Data Showing DecisionDx-Melanoma as Independent Predictor of Recurrence in Stage I Cutaneous Melanoma Population

Castle Biosciences, Inc. (NASDAQ:CSTL), a skin cancer diagnostics company providing personalized genomic information to improve cancer treatment decisions, will present data at the American Academy of Dermatology's Virtual Meeting Experience, being held April 23 -- 25, 2021. The Company has two poster presentations highlighting its DecisionDx(r)-Melanoma and DecisionDx(r)-SCC genomic tests.

Data presentation information is as follows:

DecisionDx(r)-Melanoma:

The poster is entitled, "Risk stratification of patients with stage I cutaneous melanoma (CM) using 31-gene expression profiling (GEP)."

DecisionDx-Melanoma is Castle's 31-gene expression profile test that uses an individual patient's tumor biology to predict risk of cutaneous melanoma metastasis or recurrence, as well as sentinel lymph node (SLN) positivity, independent of traditional staging factors.

Study methods and findings:

* Data were analyzed from 852 patients diagnosed with Stage I cutaneous melanoma according to the American Joint Committee on Cancer staging guidelines and a median follow-up of 3.8 years, who also had DecisionDx-Melanoma test results. Kaplan-Meier and Cox regression analyses were used to assess recurrence-free survival (RFS). Prognostic accuracy was assessed by comparing outcomes for Class 1A to outcomes for Class 2B.

* The study demonstrated that along with staging factors (Breslow thickness and ulceration), a DecisionDx-Melanoma Class 2B (highest risk) result was a significant, independent predictor of recurrence in the stage I population. A Class 2B DecisionDx-Melanoma result among these patients was associated with a recurrence rate of 20.4%, compared to the overall stage I population's recurrence risk of 4.6%. Among all stage I melanoma patients, those with a Class 2B DecisionDx-Melanoma result had seven times the odds of experiencing a recurrence than patients with a Class 1A result. In the subgroup of patients with a confirmed negative sentinel lymph node biopsy, those with a Class 2B DecisionDx-Melanoma result had five times the odds of experiencing a recurrence than patients with a Class 1A result.

* Although the stage I population has a low aggregate risk of recurrence, the study demonstrated that DecisionDx-Melanoma identified patients within that population who may experience recurrence and benefit from increased management intensity.

DecisionDx(r)-SCC:

The poster is entitled, "Prospective adjuvant therapy trial design using a prognostic 40-gene expression profile (40-GEP) test for high-risk cutaneous squamous cell carcinoma (cSCC) and BWH staging-based risk assessment."

DecisionDx-SCC is Castle's prognostic 40-gene expression profile test for patients diagnosed with high-risk cutaneous squamous cell carcinoma (SCC) designed to use a patient's tumor biology to predict individual risk of metastasis for patients with SCC and one or more risk factors.

Study methods and findings:

* This analysis evaluated the impact of DecisionDx-SCC's risk stratification as enrollment criteria into trial design involving adjuvant therapy for SCC.

* Using data from 420 validation cases, Brigham and Women's Hospital (BWH) T2a-T3 stage SCC patients with or without DecisionDx-SCC results of Class 2A/B (high risk) or 2B (highest risk) were used for two-arm sample size calculations.

* Metastasis rates for cases with BWH T2a-T3 tumors were 20% without DecisionDx-SCC results and 27% or 57% when selecting for cases with Class 2A/B or 2B results, respectively.

* In the absence of DecisionDx-SCC results, 1,234 T2a-T3 patients would be required for randomization in a trial to provide 80% power to detect a hazard ratio of 0.7 with at least three years of follow-up (alpha=0.05), correlating with studies using the addition of radiation to surgery. However, sample size could be reduced to 915 (26% reduction) or 432 (65% reduction) patients by focusing enrollment on T2a-T3 patients with a DecisionDx-SCC Class 2A/B or 2B result, respectively.

* Use of DecisionDx-SCC could be applied to improve trial inclusion criteria as it has demonstrated additive value for patient stratification in other risk assessment methods such as AJCC staging, NCCN risk groups, and individual risk factors.

* Overall, the study demonstrated that incorporation of DecisionDx-SCC testing into trial design to identify patients who are at the highest risk for metastasis could facilitate selection of those who are most appropriate for adjuvant therapy (e.g., Class 2B patients), expedite time to trial completion and optimize healthcare costs.