Castle Biosciences (CSTL)

Executive Summary

Castle Biosciences is a molecular diagnostics company providing proprietary genomic tests that guide clinical decisions for patients with skin cancers and Barrett's esophagus. Its flagship tests, DecisionDx-Melanoma and DecisionDx-SCC, are widely used to stratify risk and inform management of cutaneous melanoma and squamous cell carcinoma. The company also offers TissueCypher, a precision medicine test for Barrett's esophagus that predicts progression to esophageal cancer. Castle operates a direct-to-provider sales model and has built a strong reimbursement position, with Medicare coverage for its core tests. In 2026, the company continues to expand its test menu and invest in clinical evidence generation to drive adoption and reduce out-of-pocket costs for patients. Financially, Castle has shown consistent revenue growth and improved gross margins, reflecting its scalable lab infrastructure and growing test volumes. The company is well-positioned to capture a larger share of the dermatopathology and gastroenterology testing markets, supported by favorable guidelines and increasing awareness of genomic testing for cancer risk assessment.

Upcoming Catalysts (preview)

• Q4 2026FDA clearance or CLIA validation of next-generation sequencing panel for cutaneous squamous cell carcinoma70% success
• Q1 2027Expanded Medicare coverage for TissueCypher in Barrett's esophagus surveillance60% success
• Q3 2026Publication of prospective clinical utility study for DecisionDx-Melanoma in AJCC stage I-II patients85% success