Sidebar: Castle Protests MolDx Overlooked 2 Papers (Coverage of Squamous Test)

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https://www.360dx.com/reimbursement-news/palmetto-declines-cover-molecular-risk-stratification-tests-cutaneous-squamous

Quote:

In an email, a spokesperson for Castle Biosciences said its DecisionDx-SCC test is supported by "robust validation data in the intended use population," and since draft decision was posted last year, the firm has published "additional peer-reviewed papers addressing the perceived gaps in data that appear to have been overlooked by Palmetto."

She pointed to a study demonstrating the ability of the test to identify patients at the highest risk of metastasis who will benefift the most from adjuvant radiation therapy, and high-risk patients identified to be at lower risk of metastasis who could choose to defer treatment. 

She also mentioned a separate study that demonstrated that wen used with traditional clinicopathologic staging factors, DecisionDx-SCC "engendered significant improvement in accuracy for the prediction of metastatic events..

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The papers are ARRON 2024 and WYSONG 2024.  Both are open access.

https://www.sciencedirect.com/science/article/pii/S0360301624006850

Arron et al., Online 27 May 2024

Purpose

Adjuvant radiation therapy (ART) for cutaneous squamous cell carcinoma (cSCC) is recommended based on a number of wide-ranging clinicopathologic features, which encompass a broad array of patients. The 40-gene expression profile (40-GEP) test classifies cSCC tumors into low (Class 1) or higher (Class 2A) or highest (Class 2B) risk of nodal and/or distant metastasis. This study's hypotheses are 1) local recurrence is associated with metastatic disease progression, and 2) 40-GEP, by identifying high risk for metastasis, could predict a metastasis-specific benefit from ART.

Methods

Samples were obtained from 920 patients (ART-untreated: 496 Class 1, 335 Class 2A, 33 Class 2B; ART-treated: 11 Class 1, 35 Class 2A, 10 Class 2B) who were matched on clinical risk factors and stratified by ART status, to create 49 matched patient strata. To control for the variety of characteristics and treatment selection bias, randomly sampled pairs of matched ART and non-ART patients comprising 10,000 resampled cohorts were each analyzed for 5-year metastasis-free survival and predicted time to metastatic event.

Results

Of 96 patients experiencing local recurrence, 56.3% experienced metastasis; of those experiencing both, 88.9% had local recurrence before (75.9%) or concurrently (13.0%) with metastasis. After matching for clinicopathological risk, median 5-year disease progression rates for resampled cohorts demonstrated approximately 50% improvement for Class 2B ART-treated as compared to ART-untreated cohorts. Class 2B ART-treated cohorts had a 5-fold delay in predicted time to metastatic event and deceleration of disease progression as compared to ART-untreated cohorts (Kolmogorov-Smirnov test, p<0.01); this was not observed for Class 1 or 2A patients (p>0.05 for each). No risk factor or staging system combined with ART status identified groups that would benefit from ART as well as 40-GEP.

Conclusion

40-GEP identifies patients at highest risk of nodal/distant metastasis who may derive greatest benefit from ART, as well as patients who may have clinical indications for ART but are at low risk of metastasis. Compared to current guidelines, 40-GEP could provide greater specificity concerning the benefit of ART in individual patients.

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https://pubmed.ncbi.nlm.nih.gov/38424384/

Wysong, Epub March 1 2024

Introduction: The validated 40-gene expression profile (40-GEP) test independently stratifies risk of regional or distant metastasis for cutaneous squamous cell carcinoma (cSCC) tumors with high-risk clinicopathologic features. This study evaluated the stratification of risk by the 40-GEP test in a large cohort of tumors with one or more high-risk factors and in clinically relevant subgroups, including tumors within National Comprehensive Cancer Network (NCCN) high- and very-high-risk groups, lower-stage BWH T1 and T2a tumors, and patients > 65 years old.

Methods: This multicenter (n = 58) performance study of the 40-GEP included 897 patients. Kaplan-Meier analyses were performed to assess risk stratification profiles for 40-GEP Class 1 (low), Class 2A (higher) and Class 2B (highest) risk groups, while nested Cox regression models were used to compare risk prediction of clinicopathologic risk classification systems versus risk classification systems in combination with 40-GEP.

Results: Patients classified as 40-GEP Class 1, Class 2A, or Class 2B had significantly different metastatic risk profiles (p < 0.0001). Integrating 40-GEP results into models with individual clinicopathologic risk factors or risk classification systems (Brigham and Women's Hospital, American Joint Committee on Cancer Staging Manual, 8th Edition) and NCCN demonstrated significant improvement in accuracy for prediction of metastatic events (ANOVA for model deviance, p < 0.0001 for all models).

Conclusion: The 40-GEP test demonstrates accurate, independent, clinically actionable stratification of metastatic risk and improves predictive accuracy when integrated into risk classification systems. The improved accuracy of risk assessment when including tumor biology via the 40-GEP test ensures more risk-aligned, personalized patient management decisions.