Castle Biosciences Announces New Clinical Data Presentations at ASCO 2016 Underscoring the Accuracy and Clinical Utility of Gene Expression Profile Test for Cutaneous Melanoma

Three data presentations focused on studies of DecisionDx-Melanoma test

Company will also present data on test in development for predicting cancer
recurrence in soft tissue sarcoma

Friendswood, TX—May 19, 2016—Castle Biosciences, Inc., a provider of molecular diagnostics to improve cancer treatment decisions, today announced that several abstracts on the Company’s gene expression profile (GEP) tests for cancer were accepted for poster presentation at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting being held in Chicago, IL from June 3-7. Included in the presentations are results from a new multicenter performance study of cutaneous melanoma tumors from 334 patients, confirming the positive results from the two previously published multicenter clinical validation studies, and a new multicenter decision impact study of the DecisionDx®-Melanoma test.

Multicenter Performance Study in Cutaneous Melanoma:
In a study, titled “Performance of a 31-Gene Expression Profile in a Previously Unreported Cohort of 334 Cutaneous Melanoma Patients” (Abstract # 9581), 334 cutaneous melanoma tumors from 12 centers in the U.S. were analyzed using the DecisionDx-Melanoma gene expression profile (GEP) test. Tumors were classified as low-risk Class 1 or high-risk Class 2. The Class status was compared to traditional methods for predicting distant metastasis at diagnosis.

Summary of Results:

  • Cox univariate regression analysis of the cohort indicated that Breslow’s thickness, ulceration, mitotic rate, sentinel lymph node (SLN) status and
    results of the GEP test were significant predictors of distant metastasis risk (p<0.008 for all; median Breslow’s thickness = 1.5 mm, median follow up = 5.3 years);
  • However, only the GEP test (p=0.031) and SLN status (p= 0.002) were shown to be independent predictors of distant metastasis (Cox multivariate
    regression analysis);
  • 13 of 83 (16%) SLN negative cases had a distant metastatic event; 10 (77%) of these cases were predicted to be high-risk (Class 2 result) by the GEP test;
  • Accuracy of distant metastasis risk prediction by the GEP test showed 76% sensitivity, 55% specificity, 42% positive predictive value and 85% negative
    predictive value, compared to 72%, 64%, 45% and 84%, respectively, for SLN status.

“The results from this multicenter performance study confirm the accuracy of the test in predicting metastasis as documented in previously published clinical validation studies of DecisionDx-Melanoma,” commented Federico A. Monzon, M.D., FCAP, Chief Medical Officer of Castle Biosciences. “Our test complements traditional staging tools to better identify patients at risk for recurrence, enabling implementation of follow-up plans that are consistent with a patient’s individual risk of recurrence.”

Independent, Prospective Study in Cutaneous Melanoma:
Also at the meeting, a study titled “Prospective Validation of Gene Expression Profiling in Primary Cutaneous Melanoma” (Abstract #9565), will be presented from a prospectively designed and conducted study of 174 melanoma patients undergoing sentinel lymph node biopsy (SLNB) and testing with the DecisionDx-Melanoma GEP test. The data show that GEP classification is significantly associated with early recurrence in patients diagnosed with melanoma.

In the study, 174 melanoma patients undergoing SLNB also underwent GEP testing of their primary tumor at the time of the initial evaluation. The GEP test result was reported as Class 1 low-risk or Class 2 high-risk of metastasis, or insufficient tumor sample (INS). Median follow-up was 12 months.

Summary of Results:

  • Analysis was conducted on 159 patients with GEP test results:
    • Gender (p=0.008), Breslow’s thickness (<0.0001), ulceration (<0.0001), SLN positivity (=0.01) and Disease-Free Survival (<0.0001) were significantly associated with GEP test classification;
  • SLN was positive for 20 patients (13%) and negative for 139 patients
    • (87%):

    • Seven (35%) of 20 SLN positive patients and seven (5%) of 139 SLN negative recurred within 2 years;
  • GEP test results: 42 were high-risk Class 2 and 117 patients were low-risk
    • Class 1;

    • 13 (31%) of the 42 Class 2 patients, and one (<1%) of the 117 Class 1 patients recurred within 2 years;
  • Of 10 patients with both a Class 2 GEP status and positive SLN, seven (70%) recurred.

Multicenter, Decision Impact Study in Cutaneous Melanoma:
A third abstract related to cutaneous melanoma entitled, “Impact of Prognostic Genomic Classification of Melanoma with a 31-Gene Expression Profile on Clinical Decision-Making in a Retrospective Cohort” (Abstract #e21066), was accepted for publication at the meeting. In this study, medical records of cutaneous melanoma patients consecutively tested with DecisionDx-Melanoma at 6 medical practices from May 2013 to September 2015, were reviewed under an IRB-approved protocol. Investigators reported clinical management plans included frequency of visits, frequency and modality of imaging, use of laboratory tests and specialty referrals. Clinical management plans before and after receipt of the DecisionDx-Melanoma test results were collected to assess the impact on clinical decision making. Results showed that the GEP test outcome changed clinical management for over half of the tested patients.

Summary of Results:

  • 153 cutaneous melanoma patients met inclusion criteria with complete AJCC staging and management information:
    • 44% were Stage I, 50% Stage II, and 6% Stage III;
    • 61% (94) had low-risk Class 1 GEP test results and 39% (59) had high-risk Class 2;
  • Test results prompted a change in clinical management in 52% of patients:
    • 78% of Class 2 and 36% of Class 1 patients had management changes (p<0.0001);
  • Of the 80 cases with observed changes in management, 95% (76) were adjusted in a manner consistent with DecisionDx-Melanoma Class prediction (higher intensity management in Class 2 patients versus lower intensity management in Class 1 patients);
  • Association between GEP test class and change in management intensity was statistically significant (p< 0.0001).

“The DecisionDx-Melanoma test has now been evaluated in clinical studies that included more than 900 melanoma patient cases, with more than 400 in independent, prospectively designed trials,” commented Derek Maetzold, President and CEO of Castle Biosciences. “Each study showed a consistent, high rate of accuracy and clinical utility. These new results and the high negative predictive value rates for melanoma-specific survival observed across the DecisionDx-Melanoma studies give physicians and patients comfort when following a disease management plan based on results of staging and our GEP test.”

Development Study in Soft Tissue Sarcoma:
Also at the meeting, in a study called “Metastasis Risk Prediction in Non-Translocation Soft tissue Sarcoma with a Novel Gene Expression Profile Assay” (Abstract #11055), investigators will present data from a new test developed by Castle Biosciences to assess the risk of cancer recurrence in patients diagnosed with soft tissue sarcomas (STS). Results showed that the STS-profile assay was able to distinguish two groups with significantly different metastatic risk.

About Melanoma
Cutaneous 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 Soft Tissue Sarcoma
Soft tissue sarcoma is a type of cancer that occurs in the soft tissues of the body, including muscle, tendons, fat, lymph and blood vessels, nerves and the tissue surrounding joints. While soft tissue sarcoma can be found anywhere in the body, approximately 40% of these tumors originate in the arms and legs. There are more than 70 types of soft tissue sarcomas, which are diagnosed through physical exam, imaging tests and ultimately, biopsy. The American Cancer Society estimates approximately 12,000 new cases of soft tissue sarcomas in the United States in 2015. Treatment includes surgical removal of tumor, chemotherapy, radiation or experimental therapies administered through clinical trials.

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; and cutaneous melanoma (DecisionDx®-Melanoma;, 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

DecisionDx-UM and DecisionDx-Melanoma are the trademarks of Castle Biosciences, Inc. Any other trademarks are the property of their respective owners.

BMC Communications
Brad Miles

James L Dunn, Jr., CFO