Castle Biosciences to Present Data at SSO 2026 on DecisionDx®-Melanoma’s i31-SLNB, Identifying T1b–T2a Melanoma Patients Who May Safely Avoid SLNB
Rhea-AI Summary
Castle Biosciences (Nasdaq: CSTL) will present data at SSO 2026 (March 5–7, 2026) showing DecisionDx-Melanoma’s i31-SLNB algorithm predicts sentinel lymph node (SLN) positivity and may identify T1b–T2a melanoma patients who can safely avoid SLNB. The ePoster (EP49) reports independent validation of an integrated 31‑gene expression profile with clinicopathologic factors to provide personalized SLN risk estimates and support risk‑aligned decision-making.
ePosters will be available in the SSO Exhibit Hall, on the meeting website and in the SSO mobile app; Castle will be at booth #321.
AI-generated analysis. Not financial advice.
Positive
- Independent validation of the i31‑SLNB algorithm
- Personalized SLN risk combining 31‑GEP and clinicopathologic factors
- Identifies T1b–T2a patients who may safely avoid SLNB
Negative
- Findings presented as an ePoster, not a peer‑reviewed full manuscript
- Scope limited to T1b–T2a cutaneous melanoma patients
News Market Reaction – CSTL
On the day this news was published, CSTL declined 0.92%, reflecting a mild negative market reaction.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
CSTL was down 1.5% while key diagnostics peers were mixed: FLGT (0.14), CDNA (1.33), PSNL (0.79) up, and MYGN (-0.38), NEO (-5.6) down. With no peers in the momentum scanner and no same-day peer news, the move appears stock-specific rather than a coordinated sector reaction.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Feb 26 | Full-year 2025 results | Positive | -7.3% | Reported $344.2M 2025 revenue above guidance and strong core test growth. |
| Feb 19 | Clinical validation data | Positive | -6.8% | Prospective JAAD study validating AdvanceAD‑Tx response prediction to JAK inhibitors. |
| Feb 05 | Earnings call notice | Neutral | -7.3% | Announced date and time for Q4 and full-year 2025 earnings release. |
| Jan 11 | Preliminary 2025 results | Positive | +0.8% | Preliminary 2025 revenue expected to exceed $340M and strong test growth. |
| Dec 19 | Inducement equity grants | Neutral | -0.4% | Announced RSU inducement grants for 83 employees under 2022 Inducement Plan. |
Recent history shows several instances where seemingly positive operational or clinical updates were followed by share price declines of 6–7%, suggesting a pattern of negative reactions to good news.
Over the last few months, Castle Biosciences reported preliminary and final 2025 results with revenue of $344.2M and strong core test volume growth, yet the stock fell 7.25% on the full-year report and 7.32% on the earnings release date announcement. A positive JAAD validation for AdvanceAD‑Tx also saw a 6.8% decline. Smaller moves followed inducement grants and preliminary results. Today’s SSO 2026 presentation adds further clinical evidence supporting DecisionDx‑Melanoma, fitting into a stream of data- and volume-driven updates.
Market Pulse Summary
This announcement highlights new SSO 2026 data for the DecisionDx‑Melanoma i31‑SLNB algorithm, which integrates a 31‑gene expression profile with clinicopathologic factors to refine sentinel lymph node risk in T1b–T2a melanoma. It builds on a series of recent updates, including detailed 2025 financials and clinical validation for AdvanceAD‑Tx. Investors may monitor how additional evidence affects guideline-consistent adoption, test report volumes, and any reimbursement or coverage developments discussed in recent SEC filings.
Key Terms
sentinel lymph node biopsy medical
sentinel lymph node medical
breslow thickness medical
mitotic rate medical
gene expression profile medical
national comprehensive cancer network medical
AI-generated analysis. Not financial advice.
FRIENDSWOOD, Texas, March 04, 2026 (GLOBE NEWSWIRE) -- Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced that new data evaluating DecisionDx-Melanoma’s i31-SLNB test result for prediction of sentinel lymph node (SLN) positivity will be presented at the Society of Surgical Oncology (SSO) 2026 Annual Meeting, being held March 5-7 in Phoenix.
“The initial reports from the same prospective, multicenter study confirmed the performance of DecisionDx-Melanoma to both (i) impact sentinel lymph node biopsy (SLNB) decision-making and (ii) identify patients at low risk of nodal metastasis,” said Rebecca Critchley-Thorne, Ph.D., vice president, research and development, at Castle Biosciences. “The data being presented at SSO 2026 further extend this growing body of evidence supporting the use of DecisionDx-Melanoma to guide risk-aligned management decisions consistent with National Comprehensive Cancer Network® guideline risk thresholds, including whether to forgo, consider or pursue SLNB.”
Castle will share the following ePoster at SSO: EP49: The integrated 31-gene expression profile test identifies patients with T1b–T2a cutaneous melanoma who can safely avoid sentinel lymph node biopsy.
DecisionDx-Melanoma’s i31-SLNB algorithm integrates the independent 31-GEP score with key clinicopathologic factors, including Breslow thickness, ulceration, mitotic rate and age. This integrated approach was developed and independently validated to provide more precise risk estimation than staging criteria alone. By combining tumor biology with traditional clinical features, the algorithm generates a personalized likelihood of SLN positivity, supporting risk-aligned shared decision-making for SLNB, a surgical staging procedure commonly used to assess nodal metastasis risk.
ePosters will be available for viewing in the SSO 2026 Exhibit Hall, on the SSO Annual Meeting website and within the SSO Mobile App. The ePoster gallery will be accessible to registered attendees.
For more information on DecisionDx-Melanoma and the poster above, please visit Castle at booth #321.
About DecisionDx-Melanoma
DecisionDx-Melanoma is a gene expression profile (GEP) test designed to analyze tumor biology to deliver a personalized risk assessment for patients with stage I–III cutaneous melanoma, enhancing risk stratification beyond American Joint Committee on Cancer (AJCC) staging alone. By combining molecular insights with select clinicopathologic features, the test provides two distinct outputs: a personalized risk of sentinel lymph node (SLN) positivity and a personalized risk of recurrence and/or metastasis. This clinically actionable information is designed to help guide risk-aligned patient management decisions, including SLN biopsy consideration, follow-up intensity, imaging and referrals.
DecisionDx-Melanoma is supported by more than 50 peer-reviewed publications, including prospective studies and meta-analyses, and was developed in collaboration with more than 100 leading U.S. institutions. The test has been clinically validated in more than 10,000 patient samples, ordered more than 220,000 times since launch, and has been shown to be associated with improved patient survival. Learn more at www.CastleBiosciences.com.
About Castle Biosciences
Castle Biosciences (Nasdaq: CSTL) is a leading diagnostics company improving health through innovative tests that guide patient care. With a primary focus in dermatologic and gastroenterological disease, we develop personalized, clinically actionable solutions that help improve disease management and patient outcomes.
We put people first—empowering patients and clinicians and informing care decisions through rigorous science and advanced molecular tests that support more confident treatment planning. To learn more, visit www.CastleBiosciences.com and connect with us on LinkedIn, Instagram, Facebook and X.
DecisionDx-Melanoma, DecisionDx-CMSeq, i31-SLNB, i31-ROR, DecisionDx-SCC, MyPath Melanoma, AdvanceAD-Tx, TissueCypher, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are trademarks of Castle Biosciences, Inc.
Forward-Looking Statements
This press release contains forward-looking statements 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’s i31-SLNB test to (i) provide more precise risk estimation than staging criteria alone, (ii) support risk-aligned shared decision-making for SLNB and (iii) identify patients at low risk of nodal metastasis. The words “designed,” “may”, “can”, and similar expressions are intended to identify forward 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 actual results to differ materially from those in the forward-looking statements, including, without limitation: subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results obtained in these studies, including with respect to the discussion of our tests in this press release; actual application of our tests may not provide the aforementioned benefits to certain patients; and the risks set forth under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025, and our subsequent Quarterly Reports on Form 10-Q, each as filed or to be filed with the SEC, 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.
Investor Contact:
Camilla Zuckero
czuckero@castlebiosciences.com
Media Contact:
Allison Marshall
amarshall@castlebiosciences.com
Source: Castle Biosciences, Inc.
