Business Context and Reporting Period
Company: Castle Biosciences, Inc. (CSTL)
Filing Type: Form 10-K (Annual Report)
Reporting Period: Fiscal year ended December 31, 2025
Business Overview: Castle Biosciences is a molecular diagnostics company providing multi-analyte assays with algorithmic analysis (MAAA) to aid in the diagnosis and treatment of dermatologic cancers, Barrett's esophagus, uveal melanoma, and atopic dermatitis. The company operates laboratories in Phoenix, Arizona, and Pittsburgh, Pennsylvania.
Key Financial Metrics
| Metric | 2025 | 2024 | Change |
|---|---|---|---|
| Net Revenues | $344.2 million | $332.1 million | +3.7% |
| Net (Loss) Income | $(24.2) million | $18.2 million | Turned to loss |
| Operating (Loss) Income | $(42.8) million | $8.7 million | Significant decline |
| Gross Margin % | 69.2% | 78.5% | -9.3 pts |
| Operating Cash Flow | $64.3 million | $64.9 million | -0.8% |
| Cash & Cash Equivalents | $116.7 million | $119.7 million | -2.5% |
| Marketable Securities | $182.8 million | $173.4 million | +5.4% |
| Total Debt (Net) | $10.1 million | $10.0 million | Minimal change |
Revenue Composition: Non-dermatologic revenue (primarily TissueCypher) increased by $52.8 million (70.4% growth), offset by a $40.6 million decrease in dermatologic revenue due to the loss of Medicare coverage for DecisionDx-SCC.
Material Changes vs. Prior Period
- Loss of Medicare Coverage for DecisionDx-SCC: Effective April 24, 2025, Medicare coverage for the DecisionDx-SCC test was discontinued following Local Coverage Determination (LCD) finalizations. This resulted in a lower Average Selling Price (ASP) and a significant revenue decline in the dermatologic segment.
- Discontinuation of IDgenetix: The IDgenetix mental health test was discontinued in May 2025. This triggered a full amortization of the related intangible asset, accelerating amortization expense by approximately $20.1 million in Q1 2025.
- Acquisition of Previse: In May 2025, the company acquired Previse (Capsulomics, Inc.) for $18.7 million to expand its gastrointestinal portfolio with methylation-based technology and non-endoscopic cell collection.
- Launch of AdvanceAD-Tx: A limited launch of the AdvanceAD-Tx test for atopic dermatitis occurred in November 2025. Revenue impact was de minimis for the 2025 fiscal year.
- Headcount Growth: Employee count increased by 16% to 883 full-time employees as of December 31, 2025.
Guidance, Outlook, and Risks
Outlook and Guidance:
- Management expects existing cash, marketable securities, and anticipated revenue to fund operations for at least the next 12 months.
- Phased expansion of the AdvanceAD-Tx test is planned throughout 2026.
- The Esopredict test (from Previse) is expected to be offered as a supplemental option starting Q1 2026.
Management Commentary:
- Revenue growth is being driven by TissueCypher volume (up 86.2%) and DecisionDx-Melanoma, partially offset by the DecisionDx-SCC coverage loss.
- Operating expenses increased due to higher personnel costs, inflationary pressures, and significant amortization charges related to the IDgenetix discontinuation.
Key Risks and Contingencies:
- Reimbursement Risk: Heavy reliance on Medicare (44% of 2025 revenue) and a single commercial payor (16% of 2025 revenue). The company is currently appealing the non-coverage of DecisionDx-SCC, but the outcome is uncertain.
- Regulatory Risk: While the FDA's 2024 LDT rule was vacated in 2025, future regulatory changes regarding Laboratory Developed Tests (LDTs) remain a risk. The company holds Breakthrough Device designation for DecisionDx-Melanoma.
- Legal Proceedings: The company is responding to a subpoena from the HHS Office of Inspector General regarding billing practices and interactions with medical providers (covering Jan 2015–Feb 2024). No claims have been made, but the outcome is unpredictable.
- Profitability: The company has a history of net losses and an accumulated deficit of $224.3 million. Sustained profitability is not guaranteed.
Investor Verification Checklist
- DecisionDx-SCC Reimbursement Status: Verify the status of the reconsideration requests submitted to Novitas and MolDX regarding Medicare coverage for DecisionDx-SCC.
- AdvanceAD-Tx Adoption: Monitor Q1 and Q2 2026 test volumes and revenue recognition for the newly launched AdvanceAD-Tx test.
- Previse Integration: Assess the commercial performance of the Previse assets (Esopredict test and cell collection technology) in 2026.
- OIG Subpoena Resolution: Track any developments regarding the HHS OIG investigation into billing practices.
- Amortization Expenses: Confirm that the accelerated amortization related to IDgenetix is a one-time event and monitor future amortization schedules for acquired intangibles.
- Liquidity Position: Review the burn rate and cash runway given the shift from net income in 2024 to a net loss in 2025.