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Background
• A 31-gene expression profile (GEP) test which identifies cutaneous

melanoma tumors as low risk (Class 1) or high risk (Class 2) of
metastasis has been clinically validated.1-3

• The test has been shown to influence physicians to direct clinical
management of cutaneous melanoma patients in several clinical use
studies (Table 1).4-6

• To further assess the clinical impact of the GEP test, we undertook a
study to evaluate and compare clinical management plans
prospectively, including initial workup, follow-up intervals, and referral
patterns, established by physicians prior to and after GEP testing.

• Here we present preliminary results of this multicenter, prospective
clinical utility study to determine the clinical impact of the GEP test on
patient management plans.

Methods
• Of 269 patients enrolled in the study, 247 patients from 16 dermatology,

medical oncology and surgical oncology centers had complete data at
time of censoring (September 30, 2017).

• The RT-PCR-based GEP test was performed using primary melanoma
tumor tissue from FFPE samples. The test provides a binary
classification for risk of metastasis, Class 1 (low risk) or Class 2 (high-
risk), using a proprietary predictive modeling algorithm.

• At initial evaluation, prior to GEP testing, each patient’s pre-test
management recommendations were collected, including laboratory
tests (labs), imaging, clinical visits, adjuvant treatment discussion, and
referral to surgical or medical oncology.

• Post-test management recommendations were collected at the
subsequent visit following receipt of GEP test result.

• Pre- and post-test management plans were compared and changes
were categorized as increase, decrease, or inconclusive.

Table 4. Frequency of each modality of change in Class 2 patients with
decreases or increases in intensity of clinical management

Results
Table 2. Cohort demographics

Conclusions
• Overall, 49% of tested patients had a change in clinical management.
• The majority of reported management changes were in a risk-

appropriate direction, with 91% of decreases in care provided to low-risk
Class 1 patients and 72% of increases in care provided to high-risk
Class 2 patients.

• Physicians used GEP results to individualize management based on
biological risk, as determined by the test, while still remaining within the
context of established practice guidelines.

• Results of this prospective study show that the accurate identification of
risk provided by the GEP informs appropriate clinical management and
patient care. The proportion of patients in which the test informs
change in management is similar to that reported in three additional
clinical utility studies.4-6

References
1. Gerami P, Cook RW, Russell MC, et al. Clin Cancer Res 2015;21:175-83.
2. Gerami P, Cook RW, Wilkinson J, et al. J Am Acad Dermatol 2015;72:780-5 e783.
3. Zager JS, Messina J, Sondak VK, et al. J Clin Oncol 2016;34:9581.
4. Berger AC, Davidson RS, Poitras JK, et al. Curr Med Res Opin 201632:1599-604.
5. Farberg AS, Glazer AM, White R, Rigel DS. J Drugs Dermatol 2017;16:428-31.
6. Schuitevoerder D, Heath M, Massimino K, et al. Ann Surg Oncol 2017;24:S144.

Disclosures
CJ, KC and FAM are employees and stockholders of Castle Biosciences, Inc.
The proprietary GEP test is clinically available through Castle Biosciences as the DecisionDx®-
Melanoma test (www.SkinMelanoma.com).

Clinical impact of a 31-gene expression profile test on physician recommendations for management of melanoma patients in a prospectively tested cohort
Martin Fleming, MD1, Clare Johnson, RN2, Kyle Covington, PhD2, Joseph Gadzia, MD3, Larry Dillon, MD4, Federico A. Monzon, MD2

1The University of Tennessee Health Science Center, Memphis, TN; 2Castle Biosciences, Inc., Friendswood, TX; 3Kansas Medical Clinic, Topeka, KS; 4Dr. Larry Dillon, Colorado Springs, CO

Table 3. Clinical and molecular features across treatment groups

Figure 3. Schematic representation of risk stratification using AJCC stage
with GEP test result to guide patients’ clinical management

Clinical Characteristics Overalln=247
Median age (range), years 63 (19-94)
T stage

T1 115 (47%)
T2 66 (27%)
T3 33 (13%)
T4 18 (7%)
Not assessed 12 (6%)

Breslow thickness
Median (range), mm 1.1 (0.1-18.0)

≤1 mm 121 (49%)
>1 mm 126 (51%)

Mitotic index
<1/mm2 87 (35%)
≥1/mm2 160 (65%)

Ulceration
Absent 204 (83%)
Present 43 (17%)

Site
Trunk 77 (31%)
Extremity 124 (50%)
Head and neck 43 (17%)

GEP result
Class 1 181 (73%)
Class 2 66 (27%)

Feature
Dermatology

n=74

Surgical 
Oncology

n=166

Medical 
Oncology 

n=7
Breslowa 0.6 (0.1-10.3) 1.3 (0.1-8.0) 1.1 (0.2-18.0)
Ulcerationb

Absent 65 (88%) 133 (80%) 6 (86%)
Present 9 (12%) 33 (20%) 1 (14%)

Mitosisb
<1/mm2 38 (51%) 45 (27%) 4 (57%)
≥1/mm2 36 (49%) 121 (73%) 3 (43%)

GEP Classb*
Class 1 60 (81%) 114 (69%) 7 (100%)
Class 2 14 (19%) 52 (31%) 0 (0%)

aMedian (range), bCount (percent), *p<0.05, Fisher’s exact test

Study Result

Berger (2016)4
Prospective, multicenter
n patients = 163

53% changed mgmt after inclusion 
of GEP result

Farberg (2017)5
Dermatologist survey
n physicians = 169

47-50% changed mgmt after inclusion 
of GEP result

Schuitevoerder (2017)6
Prospective, single center
n patients = 91

52% of mgmt decision based on GEP result 
using decision tree model

Table 1. Management changes in three clinical use studies

Class 2
Decrease Increase

Labs 3 22

Imaging 4 41

Visits 1 27

Referral 3 13

Figure 1. Number of cases with a documented change in management

Class 2
n=66

Total cohort
n=247

Class 1
n=181


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