Impact of a prognostic 40-gene expression profiling test on clinical management decisions for high-risk cutaneous squamous cell carcinoma Graham H. Litchman,1 Alison L. Fitzgerald,2 Sarah J. Kurley,2 Robert W. Cook,2 Darrell S. Rigel3 1Clinical Research Fellow, National Society for Cutaneous Medicine, New York, NY 2Castle Biosciences, Inc., Friendswood, TX 3Clinical Professor of Dermatology, NYU Grossman School of Medicine, New York, NY SYNOPSIS One million cases of cutaneous squamous cell carcinoma (cSCC) are estimated to be diagnosed annually with an mortality rate of 1.5%-2%.1 A 40-gene expression profile (40- GEP) test that assesses the biology of a primary cSCC tumor was recently validated for determining metastatic potential.2 The 40-GEP test classifies patients into three risk groups: low (Class 1), high (Class 2A), and highest (Class 2B) risk for developing regional or distant metastasis within 3 years post-diagnosis. To assess the potential utility of the 40-GEP test for guiding cSCC patient management decisions, a clinical impact study was undertaken to determine if more precise risk assessment through 40-GEP testing would alter physicians’ management decisions. REFERENCES CONCLUSIONS FUNDING & DISCLOSURES OBJECTIVE Dermatology clinicians (dermatologists, nurse practitioners [NPs] and physician assistants [PAs]) attending a national dermatology conference were presented with 40-GEP test validation data. They were asked to rate clinicopathological features and molecular test results to assess their opinion of how concerning each is to cSCC prognosis (Figure 1). Vignettes describing patients with high-risk features were presented and clinicians were then asked to select a treatment plan using pre-test (no 40-GEP results), then, post-test (40-GEP Class 1, 2A, or 2B results) methodology. RESULTS Figure 1. Clinician assessment of perceived risk of metastasis with molecular 40-GEP Class and clinicopathologic features in cSCC* Table 2. Clinical characteristics of patient vignettes Table 1. Clinician demographics (n=162) Figure 2. Effect of 40-GEP test results on clinicians’ management decisions Table 3. Comparison of changes by management modality • Results from this study support that dermatologists, NPs and PAs understand the prognostic risk associated with each 40-GEP class and can appropriately incorporate 40-GEP test results to assist in management decisions for high-risk cSCC patients. • Management was altered in a risk-appropriate manner to align with metastatic risk as determined by 40-GEP Class results. • The findings of this study suggest the possibility of more appropriate management and efficient resource allocation for cSCC patients when the 40-GEP test information is included in prognostic risk assessment. 1. Skin Cancer Foundation. https://www.skincancer.org/ 2. Wysong, et al. 2020 under review JAAD This study was sponsored in full by Castle Biosciences, Inc. GHL participated in a research fellowship, which was partially funded by Castle Biosciences, Inc. DSR is a consultant and a member of the Speaker Bureau for Castle Biosciences, Inc. ALF, SJK, and RWC are employees and also hold stock options at Castle Biosciences, Inc. Years in practice resident 11.7% 1-10 years 40.7% 11-20 years 14.2% 21-30 years 19.8% >30 years 13.6% Specialty dermatologist 77.2% dermatologist/Mohs surgeon 11.1% dermatopathologist 1.2% dermatology NP/PA 8.6% other 1.9% Newly diagnosed invasive cSCC patients seen in 2019 <50 31.5% 50-100 34.0% 100-200 16.7% 200-400 14.2% >400 3.7% High-risk cSCC patients encountered ≤1% 12.3% 2-5% 34.0% 6-10% 30.2% 11-20% 14.8% >20% 8.6% cSCC staging system used I do not use any of these methods 30.9% I am not aware of these methods 13.0% I use a cSCC staging system: 56.1% AJCC7 17.6% AJCC8 58.2% BWH 24.2% NP/PA = nurse practitioner/physician assistant, AJCC7 or AJCC8 = American Joint Committee on Cancer Staging Manual Edition 7 or 8, BWH = and Brigham and Women’s Hospital Vignette Age, Sex Tumor location Size Depth of lesion Margin status Histological differentiation AJCC stage 1 67, male scalp 1.2 cm 1.2mm well-defined poor T1 2 67, male scalp 1.2 cm beyond subcutaneous fat well-defined well T3 40-GEP Class p value for comparison to feature <0.0001 <0.05 n.s. Class 1 All other features --- --- Class 2A Perineural invasion, immunosuppressed patient, Class 1 and 2B Invasion beyond subcutaneous fat Mask Area, Scalp >1cm, Below neck >2cm Class 2B Mask Area, Scalp >1cm, Below neck >2cm, Class 1 and 2A Invasion beyond subcutaneous fat Perineural invasion, immunosuppressed patient 0% 20% 40% 60% 80% 100% no 40-GEP Class 1 Class 2A Class 2B no 40-GEP Class 1 Class 2A Class 2B Sentinel Lymph Node Biopsy (SLNB) avoid consider recommend Vignette 1 Vignette 2 0% 20% 40% 60% 80% no 40-GEP Class 1 Class 2A Class 2B no 40-GEP Class 1 Class 2A Class 2B Follow-Up Intervals 1-2x per year 2-4x per year 4-12x per year Vignette 1 Vignette 2 0% 20% 40% 60% 80% 100% no 40-GEP Class 1 Class 2A Class 2B no 40-GEP Class 1 Class 2A Class 2B Nodal Imaging none nodal US or CT 1x per yr nodal US or CT 4x per yr Vignette 1 Vignette 2 0% 20% 40% 60% 80% 100% no 40-GEP Class 1 Class 2A Class 2B no 40-GEP Class 1 Class 2A Class 2B Adjuvant Radiation avoid consider recommend Vignette 1 Vignette 2 0% 20% 40% 60% 80% 100% no 40-GEP Class 1 Class 2A Class 2B no 40-GEP Class 1 Class 2A Class 2B Adjuvant Chemotherapy avoid consider recommend Vignette 1 Vignette 2 Management Modality* Vignette 1 Vignette 2 Class 1 Class 2A Class 2B Class 1 Class 2A Class 2B Reduce Increase Reduce Increase Reduce Increase Reduce Increase Reduce Increase Reduce Increase Follow-up 47 4 18 22 4 86 43 4 20 15 1 72 Sentinel Lymph Node Biopsy 59 1 11 30 2 133 83 5 25 19 0 118 Nodal Imaging 35 4 12 20 2 103 44 4 26 13 1 89 Adjuvant Radiation 53 1 11 25 1 133 71 2 27 17 2 117 Adjuvant Chemotherapy 34 1 9 26 4 112 53 2 17 15 1 104 *Fisher’s exact test with Freeman-Halton extension indicated that each row had statistically significant differences p<0.0001 when comparing Class 1, 2A, and 2B for a given modality. METHODS To determine how results from the prognostic 40-GEP test would impact clinician management decisions and how their choices would align with a risk-directed management plan for high-risk cSCC, consistent with recommendations from the National Comprehensive Cancer Network (NCCN). 40-GEP Class p value for comparison to 'no 40-GEP' Vignette 1 Vignette 2 <.0001 <.05 ns <.0001 <.05 ns Class 1 SLNB F/U, chemo, imaging, RT ---- SLNB, RT F/U, imaging, chemo ---- Class 2A ---- ---- F/U, SLNB, imaging, chemo, RT ---- ---- F/U, SLNB, imaging, chemo, RT Class 2B F/U, SLNB, imaging, chemo, RT ---- ---- F/U, SLNB, imaging, chemo, RT ---- ---- SLNB = sentinel lymph node biopsy, F/U = follow-up, chemo = adjuvant chemotherapy, imaging = nodal imaging, RT = adjuvant radiation. Using a Friedman’s test with Dunn’s multiple comparisons correction, statistical significance was determined for each vignette when all post-test 40-GEP results were compared to pre-test 40-GEP (no 40-GEP) * Graphs represent percentage of clinicians who would develop either a low (blue bar), moderate (orange bar), or high (red bar) intensity management plan based on pre-test (no 40- GEP data), then, post-test (Class 1, 2A, or 2B) results. RESULTS cont. *All clinicians surveyed were asked to rate, on a scale of 1-10 (1, lowest; 10, highest), the level of risk for metastasis associated with each of the features presented, independent of each other. Median values are plotted with error bars denoting 95% confidence intervals. P values for comparisons of risk between two features are shown in the table and reflect Friedman tests with a Dunn’s correction for multiple comparisons. Increasing Risk https://www.skincancer.org/