Castle Biosciences, Inc. (CSTL) - Q2 2026 10-Q Summary
Business Context and Reporting Period
This report covers the quarterly period ended June 30, 2026. Castle Biosciences is a commercial-stage diagnostics company focused on molecular diagnostic tests for dermatologic cancers, Barrett's esophagus, and uveal melanoma. The company operates a single reportable segment with laboratory facilities in Phoenix, Arizona, and Pittsburgh, Pennsylvania.
Key Financial Metrics
| Metric | Q2 2026 (3 Months) | YTD 2026 (6 Months) | YTD 2025 (6 Months) |
|---|---|---|---|
| Net Revenues | $103.5 million | $187.2 million | $174.2 million |
| Net (Loss) Income | $(2.1) million | $(16.6) million | $(21.3) million |
| Diluted EPS | $(0.07) | $(0.55) | $(0.74) |
| Gross Margin % | 74.9% | 74.0% | 63.1% |
| Cash & Equivalents | $62.1 million | $62.1 million | $116.7 million (Dec 31, 2025) |
| Marketable Securities | $204.7 million | $204.7 million | $182.8 million (Dec 31, 2025) |
| Total Debt (Net) | $10.1 million | $10.1 million | $10.1 million (Dec 31, 2025) |
| Operating Cash Flow | Not provided for Q2 | $(6.9) million | $14.8 million |
Material Changes vs. Prior Period
- Revenue Growth: Net revenues increased 20.1% in Q2 2026 and 7.5% YTD 2026 compared to the prior year. This was driven by a 61% increase in test volume for the non-dermatologic TissueCypher test, which now represents over 50% of total revenue.
- Dermatologic Decline: Dermatologic revenues decreased 13.5% in Q2 and 24.7% YTD, primarily due to the loss of Medicare coverage for the DecisionDx-SCC test effective April 2025, resulting in lower volumes and realized average selling prices.
- Profitability Improvement: The net loss narrowed significantly YTD 2026 compared to 2025. Gross margin percentage improved to 74.0% YTD 2026 from 63.1% in 2025, largely due to the cessation of accelerated amortization for the discontinued IDgenetix test.
- Cash Position: Cash and cash equivalents decreased by $54.6 million YTD 2026, driven by negative operating cash flow of $6.9 million and net investing outflows of $41.8 million (primarily purchases of marketable securities and property/equipment).
Guidance, Outlook, and Risks
- Outlook: Management believes existing cash, marketable securities, and anticipated revenue will fund operations for at least the next 12 months. The company is expanding laboratory capacity in Pittsburgh to support TissueCypher growth and is in the limited access launch phase for the new AdvanceAD-Tx test for atopic dermatitis.
- Reimbursement Risks: The company is actively appealing the loss of Medicare coverage for DecisionDx-SCC. Future revenue stability depends heavily on maintaining coverage for core products and securing reimbursement for new launches.
- Legal Proceedings: The company is responding to a subpoena from the U.S. Department of Health and Human Services, Office of Inspector General, regarding billing practices for federal healthcare programs. No claims have been made, and the potential financial impact cannot be estimated.
- Debt Covenants: The company is in compliance with all covenants under its $10 million term loan, which is interest-only through December 2026.
Investor Verification Checklist
- Medicare Appeals: Verify the status of the reconsideration requests for DecisionDx-SCC coverage with Novitas and MolDX.
- AdvanceAD-Tx Adoption: Monitor the transition of the AdvanceAD-Tx test from limited access to full commercial launch and its impact on revenue mix.
- Operating Cash Flow: Assess the sustainability of negative operating cash flow in the current period versus the positive flow in the prior year, specifically regarding working capital changes and bonus payments.
- Regulatory Inquiry: Track developments regarding the HHS OIG subpoena to evaluate potential liability or reputational risk.
- Debt Maturity: Confirm the timeline for principal repayments on the $10 million term loan commencing in December 2026.