Castle Biosciences Announces Publication of Prospective Multicenter Study Demonstrating that its DecisionDx-Melanoma Test can Inform Sentinel Lymph Node Biopsy Decisions
Validation data from 1,421 patients published in Future Oncology
Friendswood, TX – January 30, 2019 – Castle Biosciences, Inc., a skin cancer diagnostics company providing personalized genomic information to improve cancer management decisions, today announced publication of data supporting clinical use of the DecisionDx®-Melanoma test to inform decisions for use of sentinel lymph node biopsy (SLNB), a surgical procedure used to help stage melanoma. The study found that the DecisionDx-Melanoma test result can be used with clinicopathologic factors to inform patient discussions and recommendations for SLNB in line with national melanoma clinical practice guidelines. The study was published in Future Oncology.
Key Study Findings:
- National guidelines recommend the SLNB surgical procedure to assess prognosis of melanoma patients whose tumor features suggest at least a 5% likelihood of sentinel lymph node (SLN) positivity. The guidelines do not generally recommend the procedure if a patient has a likelihood of SLN positivity of less than 5% because of the false negative rate of the surgical procedure, associated complication risks and cost.
- This study was designed to determine if the DecisionDx-Melanoma 31-gene expression profile (GEP) test could help identify patients with a low risk of SLN positivity (<5%) and validate this intended use.
- Predictive modeling indicated the DecisionDx-Melanoma test in combination with tumor depth (T category) and patient age could predict SLN positivity, and this strategy was validated in two independent, prospective, multicenter cohorts totaling 1,421 patients. Patients had a median age of 63 years, median Breslow depth of 1.16 millimeters and 21.4% had ulceration present.
- For patients with T1-T2 tumors (≤2.0 millimeters in depth) and a Class 1A test result (lowest risk of recurrence), the risk of SLN positivity was 4.6%. For the subgroup of patients who were 55 years or older the risk decreased to 2.8% and 1.6% for those 65 years or older. Guidelines generally do not recommend the SLNB surgical procedure for patients whose SLN positivity risk is below 5%.
- For patients of all ages with T1-T2 tumors who had a Class 2B test result (highest risk of recurrence), the risk of SLN positivity was 18.8%. Guidelines suggest that the SLNB surgical procedure should be offered to patients whose SLN positivity risk exceeds 10%.
- To estimate the clinical outcomes of Class 1A patients who would not undergo the SLNB surgical procedure based on a low likelihood for a positive result, a retrospective dataset of 690 patients with long-term follow-up was used. Importantly, at 5 years, Class 1A patients with T1-T2 tumors had a melanoma-specific survival rate of 99.6%, overall survival rate of 98.2%, and distant metastasis-free survival rate of 95.3%.
“The GEP test result, along with tumor thickness and patient age, can help identify a group of patients with melanoma who may avoid the SLNB procedure based on national clinical melanoma guidelines,” said the study lead author John Vetto, M.D., Professor of Surgery, Division of Surgical Oncology and Director of the Cutaneous Oncology Program at the Department of Surgery, Oregon Health & Science University. “Providing physicians with accurate risk information to better inform patient discussions about SLNB options is an important advance in the management of melanoma, which can help us better direct resources to patients that really need them.”
The full published study results can be accessed at the Future Oncology website.
Sentinel Lymph Node Biopsy Background
SLNB is a surgical procedure generally recommended to assess prognosis in cutaneous melanoma patients. The procedure provides prognostic information and can determine eligibility for adjuvant therapies, but can be associated with complications, adding a significant economic burden to the healthcare system.
Current guidelines recommend that clinicians discuss and/or offer the SLNB procedure with patients who have a 5% or greater likelihood of SLN positivity, and do not recommend the procedure if a patient has a less than 5% likelihood of a positive SLN. For patients who are SLNB eligible, the DecisionDx-Melanoma test can inform SLNB decision-making by identifying a group of patients with low-risk tumor biology who are less than 5% likely to be SLN positive, and thus can safely avoid the procedure.
The DecisionDx-Melanoma test uses tumor biology to predict individual risk of melanoma recurrence and sentinel lymph node positivity independent of traditional factors and has been studied in over 2,900 patients. Using tissue from the primary melanoma, the test measures the expression of 31 genes. The test has been validated in three multi-center studies that have included 690 patients and have demonstrated consistent results. Performance has also been confirmed in five prospective studies including over 780 patients. The consistent high performance and accuracy demonstrated in these studies, which combined have included over 1,470 patients, provides confidence in disease management plans that incorporate DecisionDx-Melanoma test results.
Prediction of the likelihood of sentinel lymph node positivity has also been validated in two prospective multicenter cohorts that included over 1,400 patients. Impact on patient management plans for one of every two patients tested has been demonstrated in multi-center and single-center studies. More information about the test and disease can be found at www.SkinMelanoma.com.
About Castle Biosciences
Castle Biosciences is a skin cancer diagnostics company dedicated to helping patients and their physicians make more informed decisions about treatment and follow up care based on the individual molecular signature of the patient’s tumor. The Company currently offers tests for patients with cutaneous melanoma (DecisionDx®-Melanoma, DecisionDx®-CMSeq; www.SkinMelanoma.com) and uveal melanoma (DecisionDx®-UM, DecisionDx®-PRAME and DecisionDx®-UMSeq; www.MyUvealMelanoma.com), with programs in development for other underserved cancers, the most advanced of which is focused on patients with cutaneous squamous cell carcinoma. Castle Biosciences is based in Friendswood, Texas (Houston), and has laboratory operations in Phoenix, Arizona. More information can be found at www.CastleBiosciences.com.
DecisionDx-Melanoma, DecisionDx-CMSeq, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are the trademarks of Castle Biosciences, Inc. Any other trademarks are the property of their respective owners.
Derek Maetzold, President and CEO