Company also presented data highlighting strong reproducibility of results with new PRAME gene expression profile test for eye cancer
Friendswood, TX – November 10, 2016 – Castle Biosciences, Inc., a provider of molecular diagnostics to improve cancer treatment decisions, today announced results from a study evaluating the clinical impact of its gene expression profile (GEP) test DecisionDx®-Melanoma on patient management decisions. The test uses tumor biology to provide an individual risk of recurrence in cutaneous (skin) melanoma patients. The data were presented in a poster session at the Society for Melanoma Research 2016 Congress, which was held in Boston, MA from November 6–9. Additionally, data from the analytical validation of DecisionDx®-PRAME, the Company’s new GEP test designed to measure gene expression levels of Preferentially Expressed Antigen in Melanoma (PRAME) in certain eye cancer patients, demonstrated strong reproducibility of test results. Elevated expression of the PRAME gene has been linked to an increased risk of metastasis in uveal melanoma (UM) patients.
Clinical Impact Analysis of DecisionDx-Melanoma: Study Details
In a study titled, “Clinical Impact of a 31-Gene Expression Profile Test on Guidance of Sentinel Lymph Node Biopsy, Imaging and Oncology Referral,” 169 physicians were presented with clinical validity evidence for the cutaneous melanoma (CM) GEP assay, followed by descriptions of six clinical vignettes for melanoma patients commonly evaluated in high-volume dermatology practices. The respondents were asked how a Class 1 (low-risk) and Class 2 (high-risk) GEP test result, in addition to traditional clinicopathologic features, would affect their clinical recommendations. Respondents were also asked to provide the Breslow thickness (ranging from 0.7-1.5mm in 0.1mm increments) at which they would change management with and without the information provided by the GEP test.
- The overall results indicate that the use of the GEP test, in conjunction with standard staging factors, significantly impacts CM patient management according to individual risk and within the context of current established practice guidelines;
- A majority of respondents indicated a Breslow thickness of 1.0mm as the thickness at which they would recommend a patient for sentinel lymph node biopsy (SLNB), oncology referral and imaging (62%, 57%, and 55%, respectively), reflecting adherence to current management guidelines;
- For a Class 1 (low-risk) outcome, the initial Breslow thickness used to guide these clinical recommendations was changed for 23%, 18% and 19% of cases, respectively. These changes were risk-appropriate with the inflection point changed to an increased Breslow thickness in a majority of cases;
- For a Class 2 (high-risk) outcome, the initial Breslow thickness used to guide these clinical recommendations was changed for 47%, 50% and 47% of cases, respectively. These changes were risk-appropriate with the inflection point changed to a decreased Breslow thickness in a majority of cases (95%, 84% and 97%, respectively).
“As clinicians, we struggle with decisions regarding appropriate management and appropriate follow-up recommendations for patients with cutaneous melanoma,” noted study co-author Darrell Rigel, M.D., M.S., Clinical Professor at New York University School of Medicine. “This study demonstrates that having the additional tumor biology data impacts risk appropriate clinical decisions.”
Validation Study of DecisionDx-PRAME in Uveal Melanoma
Also at the meeting, in a study called “Analytic Validation of a Clinical Test for PRAME Gene Expression Status in Primary Uveal Melanomas,” the Company presented data from an analytical validation study of DecisionDx-PRAME, demonstrating robust inter- and intra-assay reproducibility. The new GEP test was designed to determine expression levels of the PRAME gene. Elevated expression of PRAME has been linked to an increased risk of metastasis in UM patients. The DecisionDx-PRAME test is being offered as an optional add-on test for patients undergoing evaluation with Castle Biosciences’ market-leading DecisionDx®-UM prognostic test.
- A previously identified PRAME threshold to determine PRAME positivity was validated in an expanded cohort of 958 UM tumors with PRAME qPCR data;
- PRAME test results showed high inter- and intra-assay reproducibility;
- In 958 patients, about 30% of patients are PRAME positive, with Class 2 (high-risk) patients more likely to be PRAME positive than Class 1A or 1B;
- In enucleated tumors, PRAME status was not significantly associated with any pathologic features suggesting these factors are not indicative of PRAME expression in such tumors that necessitated enucleation.
About Cutaneous Melanoma
Cutaneous (skin) melanoma is diagnosed in approximately 76,000 people in the U.S. each year, according to the American Cancer Society. Seventy-five percent are diagnosed as Stage I or II, meaning there is no evidence of the melanoma spreading beyond the primary tumor. It is not the most prevalent form of skin cancer, but it is the most aggressive. Unlike other more common skin malignancies such as basal cell and squamous cell carcinomas, melanoma often spreads to other parts of the body, either via the lymphatic or blood system, resulting in cancers of distant organs including the brain or lungs. So, while it represents just 4% of skin cancers, melanoma accounts for about 80% of skin cancer-related deaths.
About Uveal Melanoma
Uveal melanoma, while rare, is the most common form of eye cancer in the United States with about 1,600 diagnoses per year. This form of eye cancer may occur in any of the three parts of the uvea. Similar to other melanomas, uveal melanoma begins in cells called melanocytes that help produce the pigments of the skin, hair and eyes. While more common in patients who are middle-aged with fair skin, uveal melanoma can affect people of all complexions and ages.
Although a small percentage (3%) of patients with uveal melanoma have detectable metastatic lesions at the time of diagnosis or treatment of the primary tumor, up to 50% of patients will subsequently develop metastatic disease. This necessitates a rigorously validated, accurate and reliable tool to identify patients likely to develop distant metastasis.
About Castle Biosciences
Castle Biosciences is a molecular diagnostics company dedicated to helping patients and their physicians make the best possible decisions about their treatment and follow up care based on the individual molecular signature of their tumor. The Company currently offers tests for patients with uveal melanoma (DecisionDx®-UM; www.MyUvealMelanoma.com, and DecisionDx®-PRAME) and cutaneous melanoma (DecisionDx®-Melanoma; www.SkinMelanoma.com), with development programs in other underserved cancers. Castle Biosciences is based in Friendswood, TX (Houston), and has laboratory operations in Phoenix, AZ. More information can be found at www.castlebiosciences.com.
DecisionDx-UM, DecisionDx-Melanoma and DecisionDx-PRAME are the trademarks of Castle Biosciences, Inc. Any other trademarks are the property of their respective owners.
James L Dunn, Jr., CFO