Second Systematic Review and Meta-Analysis Published Demonstrating DecisionDx-Melanoma as Independent Predictor of Recurrence, Distant Metastasis and Overall Survival in Cutaneous Melanoma

The article titled, “A Systematic Review and Meta-Analysis of Gene Expression Profiling for Primary Cutaneous Melanoma Prognosis,” appeared in SKIN: The Journal of Cutaneous Medicine.

The study found that of all gene expression profile tests reported for cutaneous melanoma, DecisionDx-Melanoma was the only test described in the literature or commercially available with sufficient evidence to qualify for inclusion in the study. This is the second recently published systematic review and meta-analysis that demonstrates the independence and significance of DecisionDx-Melanoma prognosis for recurrence and metastatic risk in patients with invasive cutaneous melanoma.

Lichtman et al. Study Background and Results:

• The purpose of this systematic review and meta-analysis was to consolidate the rapidly evolving body of data on gene expression profiling (GEP) in melanoma prognosis.
• This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)¹.
• The systematic review identified several GEP assays that have been described in the literature. However, aside from DecisionDx-Melanoma, none of the reported studies were supported by consistent reporting of results or enough evidence for inclusion in the meta-analysis performed by study co-authors.
• The DecisionDx-Melanoma test was found to be a consistent, independent and significant predictor of survival, with a significant association between Class 2 test results and recurrence-free (Hazard Ratio [HR] = 7.22; p <0.00001), distant metastasis-free (HR = 6.62; p <0.00001) and overall (HR = 7.06; p <0.00001) survival rates.
• DecisionDx-Melanoma test results were also associated with sentinel lymph node biopsy status (odds ratio calculation; p<0.00001).

Results of the study indicate that the DecisionDx-Melanoma test achieved the highest Strength of Recommendation Taxonomy (SORT) level of evidence for a prognostic biomarker (Level 1 evidence). The SORT system is used by the American Academy of Dermatology (AAD) and other organizations to evaluate the quality, quantity and consistency of evidence supporting tests such as DecisionDx-Melanoma. The SORT scale evaluates both the quality of the evidence (Level 1, 2 or 3) and strength of the recommendation (A, B or C).

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 March 31, 2020, DecisionDx-Melanoma has been ordered more than 56,800 times for use in patients with cutaneous melanoma.

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

About Castle Biosciences

Castle Biosciences (Nasdaq: CSTL) is a commercial-stage dermatologic cancer company focused on providing physicians and their patients with personalized, clinically actionable genomic information to make more accurate treatment decisions. 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 products in development for other underserved cancers, the two most advanced of which are focused on patients with cutaneous squamous cell carcinoma, and patients who have a difficult-to-diagnose pigmented lesion. Castle Biosciences is based in Friendswood, Texas (Houston), and has laboratory operations in Phoenix, Arizona. For more information, visit www.CastleBiosciences.com.

DecisionDx-Melanoma, DecisionDx-CMSeq, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are trademarks of Castle Biosciences, Inc.

Forward-Looking Statements

The information in this press release contains forward-looking statements and information within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are subject to the “safe harbor” created by those sections. These forward-looking statements include, but are not limited to, statements concerning the ability of DecisionDx-Melanoma test results to predict recurrence and metastatic risk in patients with invasive cutaneous melanoma. The words “anticipates,” “believes,” “estimates,” “expects,” “intends,” “may,” “plans,” “projects,” “will,” “would” and similar expressions are intended to identify forward-looking statements; although, not all forward-looking statements contain these identifying words. We may not actually achieve the plans, intentions, or expectations disclosed in our forward-looking statements and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements that we make. These forward-looking statements involve risks and uncertainties that could cause our actual results to differ materially from those in the forward-looking statements, including, without limitation, the risks set forth in our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 10, 2020, our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, filed with the SEC on May 11, 2020, and in our other filings with the SEC. The forward-looking statements are applicable only as of the date on which they are made, and we do not assume any obligation to update any forward-looking statements, except as may be required by law.

¹ From the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement: Under PRISMA, a systematic review evaluates a clearly formulated question using systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. Statistical methods (meta-analysis) may or may not be used to analyze and summarize the results of the included studies. Meta-analysis refers to the use of statistical techniques in a systematic review to integrate the results of included studies.

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