DecisionDx®-Melanoma's i31-SLNB Outperforms MIA Nomogram in Identifying Patients Who May Safely Forgo Sentinel Lymph Node Biopsy
Castle Biosciences (Nasdaq: CSTL) said a prospective multicenter study in Dermatology and Therapy found its DecisionDx-Melanoma i31-SLNB test more accurately predicts sentinel lymph node (SLN) positivity than the Melanoma Institute Australia (MIA) nomogram. In 912 patients, i31-SLNB low-risk cases had 2.6% observed SLN positivity vs 5.8% for MIA; i31-SLNB AUC was 0.74 vs 0.61 (p=0.001).
How this was made
The 30-second read
Why it matters
The DECIDE prospective cohort compares CSTL’s i31-SLNB (31-gene expression profile plus clinicopathologic factors) versus the MIA nomogram, showing better calibration at the <5% threshold and improved classification in discordant cases.
Market read
New prospective evidence claims better accuracy for CSTL’s test at clinically relevant SLN-avoidance thresholds, which can support adoption and payer/clinician confidence.
What to watch
The article does not quantify commercial impact (test volumes, payer coverage, pricing) or provide safety/clinical outcome endpoints beyond SLN positivity prediction.
Background
SLNB is used for melanoma staging, but many procedures are negative; guidelines use risk thresholds (e.g., NCCN <5% to consider avoiding SLNB).
Ticker impact
Castle Biosciences reports a prospective multicenter study where its DecisionDx-Melanoma i31-SLNB outperforms the MIA nomogram for SLN risk prediction.
Near-term sentiment tailwind for CSTL on improved clinical validation; magnitude likely limited without reimbursement/coverage or regulatory milestones.
The article provides new prospective cohort performance metrics (AUC, discordance rates) tied directly to CSTL’s product, but it is a PR/clinical validation update rather than a financial or regulatory catalyst.
Market effects
Supports the broader trend toward molecular diagnostics improving surgical decision-making in oncology, potentially benefiting sentiment for precision diagnostics.
No clear regional read-through beyond US-listed diagnostics.
Limited global impact unless followed by guideline/reimbursement changes; study may influence international melanoma care discussions.
Counterpoint
Improved discrimination metrics may not translate into faster adoption if payers, clinicians, or guidelines do not change thresholds or coverage policies.
Key entities
- companyCastle Biosciences, Inc.
Developer of DecisionDx-Melanoma i31-SLNB test; subject of the prospective study announcement.
- productDecisionDx-Melanoma i31-SLNB
Integrated sentinel lymph node biopsy test using a 31-gene expression profile plus clinicopathologic factors.
- clinical toolMelanoma Institute Australia (MIA) nomogram
Clinicopathologic-only model estimating SLN positivity risk used for comparison in the study.
