From eczema to melanoma — how Castle Biosciences is reading the genetic code of skin disease to match every patient to the right treatment.

For patients with moderate-to-severe atopic dermatitis, the current standard of care is a costly, time-consuming process of elimination: try a biologic, wait months, fail, try a JAK inhibitor, wait again. Castle Biosciences has built a test designed to end that cycle. AdvanceAD-Tx is a 487-gene expression profile that reads the underlying immune biology of a patient’s eczema and classifies them as either a JAK Inhibitor Responder Profile or a Th2 Molecular Profile — giving physicians a biological roadmap before the first prescription is written. First-in-class, with no direct U.S. competitors, it is available for patients 12 years and older. But Castle Biosciences’ precision medicine platform extends well beyond eczema. The company’s flagship product, DecisionDx-Melanoma, is a 31-gene expression profile test that uses a patient’s own tumor biology to predict the risk of metastasis and sentinel lymph node positivity, independent of traditional AJCC staging. Studied in more than 10,000 patients, backed by more than 50 peer-reviewed publications, and clinically ordered by more than 60% of U.S. dermatologists in over 200,000 patients, DecisionDx-Melanoma is the only melanoma GEP test known to be associated with improved patient outcomes in the published literature. For patients, caregivers, clinicians, and investors at the intersection of genomics and dermatology — this is the segment to watch.