On January 20, 2020 Castle Biosciences, Inc. (Nasdaq: CSTL), a skin cancer diagnostics company providing personalized genomic information to improve cancer treatment decisions, reported the presentation of clinical utility data for its cutaneous squamous cell carcinoma (SCC) prognostic test, DecisionDx-SCC, for patients diagnosed with high-risk cutaneous SCC (Press release, Castle Biosciences, JAN 20, 2020, View Source [SID1234553344]). The test is expected to be launched commercially in the second half of 2020.

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The poster titled, "Integrating the 40-Gene Expression Profile (40-GEP) Test into Management of High-Risk Cutaneous Squamous Cell Carcinoma," was presented during the 2020 Winter Clinical Dermatology Conference, January 17-22 in Hawaii.

The data presented support a framework for integration of DecisionDx-SCC into risk-appropriate management of high-risk cutaneous SCC patients (as defined by the National Comprehensive Cancer Network [NCCN]).

Disease and Study Background

Approximately 1 million patients are diagnosed with cutaneous SCC in the U.S. each year, and the incidence continues to grow.
As with other cancer types, NCCN guidelines define treatment pathways based on risk of metastasis. In the case of cutaneous SCC, there are two clinicopathologically defined categories: low-risk and high-risk.
The Company believes two important issues exist in implementing a high-risk treatment pathway. First, the NCCN risk criteria, as well as available staging systems, have low positive predictive value (PPV) – meaning that the majority of high-risk patients do not develop metastasis; and, second, the high-risk treatment pathways are broad.
The clinical implication being that many patients categorized as high risk, but who have a low biological risk of metastasis, may be overtreated with radiation, chemotherapy or other interventions; and those patients categorized as high risk and who also have a high biological risk of metastasis may be undertreated if clinical decisions are to follow a conservative treatment plan within the broad boundaries of NCCN high-risk pathways.
The Company believes improved stratification for implementation of risk-appropriate treatment plans for patients within NCCN-defined high-risk cutaneous SCC is needed. NCCN defines high risk as cutaneous SCC patients with a single high-risk feature, e.g., immunodeficiency; tumor diameter greater than or equal to 2cm; any tumor of the mask area, genitals, hands, or feet; or poor tumor differentiation.
DecisionDx-SCC was developed and validated to stratify risk of regional or distant metastasis at three years after diagnosis in high-risk cutaneous SCC patients, classifying patients as low (Class 1), high (Class 2A) or highest (Class 2B) risk of metastasis.
This study was designed to evaluate the integration of DecisionDx-SCC (40-GEP test) with AJCC and Brigham and Women’s Hospital (BWH) T stage criteria into management of 300 NCCN high-risk cutaneous SCC patients.
Within the broad framework of NCCN recommendations for high-risk cutaneous SCC, the aim is to identify those high-risk patients who would be eligible for a conservative, reduced treatment plan, thus avoiding unnecessary adjuvant interventions, and identifying those patients who would most benefit from aggressive adjuvant treatment strategies.
Study Findings

Integration of DecisionDx-SCC for NCCN-defined high-risk cutaneous SCC patients with T staging identified a group of 159 patients (Class 1, T1-T2) with a 7.5% rate of metastasis, which approaches that of the general cutaneous SCC patient population. A low intensity management strategy, within the broad NCCN high-risk guidelines, could spare this patient group unnecessary adjuvant procedures and potential adverse effects.
Conversely, those patients (n=24) with rates of metastasis surpassing 50% (Class 2B), regardless of AJCC or BWH T stage, would warrant a high intensity strategy, also within the broad NCCN high-risk guidelines, that increases follow-up visits, utilizes imaging and/or biopsies for nodal assessment, and offers adjuvant treatments and clinical trials for probable metastatic events.
The data support a framework for risk-aligned treatment plans when DecisionDx-SCC is incorporated into management of NCCN high-risk cutaneous SCC patients.
"There is a clear need to improve identification of true high-risk and lower-risk patients diagnosed with high-risk cutaneous SCC, so that risk-directed treatment plans can be implemented," said Aaron Farberg, M.D., study investigator, Icahn School of Medicine at Mount Sinai, New York and Arkansas Dermatology Skin Cancer Center, Little Rock, Arkansas. "Clinical use of DecisionDx-SCC, along with current staging systems, may better identify patients with cutaneous SCC at high risk for metastasis and enable more informed clinical decisions regarding adjuvant therapy and other management options."

The DecisionDx-SCC test is the second skin cancer test discovered, developed and validated by Castle Biosciences.

About Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (SCC), a nonmelanoma skin cancer, is one of the most common cancers. Approximately 1,000,000 patients are diagnosed with cutaneous SCC each year in the U.S. Most patients have a favorable prognosis, but a subset of patients will develop metastasis, and up to 15,000 patients each year die from their disease, exceeding the number of deaths from cutaneous melanoma. As current staging parameters have a low positive predictive value, many more patients are considered high risk than actually develop metastatic disease. Conversely, many patients who develop metastatic disease are misidentified as low risk. This may lead to over and undertreatment of a substantial number of cutaneous SCC patients. To address this clinical need, Castle Biosciences has developed a gene expression profile test designed to improve upon current staging systems and identify patients with cutaneous SCC at high risk for metastasis or recurrence, in order to enable more informed clinical decisions regarding adjuvant therapy and other management options.