This Medicare contractor will provide limited coverage for the DecisionDx-UM
(Castle Bioscience, Inc.) test for the management of newly diagnosed uveal
melanoma. This test is intended for the determination of metastatic risk, and
to guide surveillance and referral to medical oncology (preferably an
oncologist with expertise in melanoma) in patients who have a confirmed
diagnosis of uveal melanoma (UM) and no evidence of metastatic disease.

UM is a rare cancer, affecting ~1600-1700 patients per year in the United
States, but it is the most common intra-ocular cancer in adults. UM arises in
the middle layer of the eye, the uvea tract, which consists of the iris,
ciliary body, and choroid. Eye-sparing radiation (brachytherapy or proton beam
therapy) is the most common treatment approach, but approximately 10% of
patients will undergo enucleation due to large and/or aggressive tumors that
cannot be managed with radiation or due to eye pain or vision loss. Local
treatment by radiation or enucleation is highly successful at controlling the
primary tumor, with only ~5% chance of local recurrence. Most patients present
with local disease and no evidence of metastases, however, as many as 50% of
patients will ultimately experience distant metastasis, most commonly to the
liver.  
  
Clinicopathologic staging cannot reliably identify patients at low or high
risk of metastasis, as even early stage patients (AJCC Stage I-II) have a
substantial risk of metastasis and mortality. Historically, most UM patients
were managed with high intensity surveillance, including frequent imaging and
laboratory tests, with the goal of diagnosing early metastasis. Systematic
imaging has been shown to be effective at identifying asymptomatic metastases,
which is important because treatment of liver metastases with surgical
resection or regional therapy is more effective and achieves better outcomes
when tumor burden is low. However, since approximately 50% of patients will
not experience metastasis, a substantial proportion of patients were subjected
to unnecessary imaging, laboratory tests, and clinical visits, resulting in
patient burden, undo exposure to radiation and over-utilization of healthcare
resources.  
  
An accurate determination of metastatic risk at diagnosis allows for a risk-
appropriate surveillance program. Patients at high-risk of metastasis can
continue to be followed with a high intensity program as previously
prescribed, such as quarterly ultrasound, magnetic resonance imaging (MRI) or
computerized tomography (CT) scans alternating with liver function tests
(LFTs), and consideration of adjuvant treatment. These patients benefit from
early detection of metastatic disease when it can be most effectively treated.
Patients with low metastatic risk can be removed from this traditional
intensive surveillance and instead followed with a low intensity program, such
as yearly exams, imaging, and LFTs.

**DecisionDx-UM Test Description and Intended Use**

DecisionDx-UM is an ribonucleic acid (RNA) gene expression classifier that is
based on the expression levels of 15 mRNA transcripts (3 control and 12
discriminating genes). DecisionDx-UM is performed on tissue from a fresh-
frozen fine needle aspirate biopsy (FNAB), formalin-fixed paraffin embedded
(FFPE) sections from an enucleated tumor, or, in rare cases, fresh-frozen
resection material. Results are reported as a 5-year risk classification for
metastasis: low risk (Class 1A), intermediate risk (Class 1B), or high risk
(Class 2).

The DecisionDx-UM test is intended for determination of metastatic risk, and
to guide surveillance and referral to medical oncology in patients who have a
confirmed diagnosis of UM and no evidence of metastatic disease. The test
discriminates patients with high risk (class 2) for early distal recurrent
disease from those with minimal risk of distal metastasis (class 1A).
Identification of high-risk patients allows early referral to a medical
oncologist with expertise in the management of UMs, which includes intensified
metastatic surveillance and/or metastasis intervention, and stratification for
entry into clinical trials with adjuvant therapy. In rare cases where the
patient cannot realistically see a medical oncologist due to geographic
location (long distance to travel), and/or are among underserved patient
populations, if they cannot feasibly see a medical oncologist, surveillance
testing for class 2 patients can be directed by an ophthalmologist with
specific training in treating patients with UM.  
  
**Clinical Validation**  
  
In both prospective and retrospective multicenter studies, DecisionDX-UM has
been shown to be a more accurate prognostic indicator of metastasis compared
to any other factor.1-4

Onken et al1 reported the migration of the RNA expression profile from a
hybridization-based microarray platform to a polymerase chain reaction
(PCR)-based 15 gene assay and analyzed the technical performance of the assay
in a prospective study of FNAB tumor samples from multiple centers. The gene
expression profile distinguished between low metastatic risk (class 1
signature) and high metastatic risk (class 2 signature). The role of RNA
quality and tumor heterogeneity was evaluated. A clinically annotated training
set of 28 UMs was used to support the vector machine algorithm for
classification. One hundred seventy-two patients from a single center with a
median follow-up of 16 months were utilized to evaluate prognostic performance
which demonstrated technical performance of 94.8%. Kaplan-Meier analysis
showed an accuracy of risk-classification with 5-year metastatic-free survival
(MFS) rates of 98% and 24% for predicted Class 1 and 2 cases, respectively (P
< 0.0001).1  
  
The Collaborative Ocular Oncology Group study was a prospective, multi-center,
blinded study to assess clinical validity of the DecisionDx-UM test.2
Comparison with other genetic and clinicopathologic variables was evaluated.
Of 494 patients, 446 were considered evaluable. The 50-month metastasis-free
survival was 97% vs 20% for Class 1 and 2 respectively (p<0.0001). By Cox
multivariate proportional hazards analysis, Class 2 identified metastasis
better than any other prognostic factor (p<0.006). The Net Reclassification
Improvement study showed improvement of gene expression profiling over TNM (T
describes size of primary tumor, N describes regional lymph nodes status, M
describes distant metastasis) classification of 37% at 2 years (p=0.008) and
43% at 3 years (p=0.001). When compared to chromosome 3 status, the
improvement of gene expression profiling over TNM was 36% at 2 years (p=
0.006) and 38% at 3 years (p=0.004).2  
  
In a retrospective, single-center clinical study designed to assess clinical
validity of the DecisionDx-UM test, in 187 patients, Chappell, et al3 showed
disease specific survival was predicted with high accuracy. Kaplan-Meier
analysis for 5-year disease specific survival was 93% and 38% for Class 1 vs 2
cases, respectively (p<0.0001). By multivariate Cox modeling, the DecisionDx-
UM class was the only independent significant predictor of outcome for both
metastasis-free survival (HR=8.4, p<0.0001) and disease-specific survival
(HR=12.3, p<0.0001).  
  
Another prospective, single-center clinical study evaluated the clinical
validity of the DecisionDx-UM test in 299 UM patients. In this study, Cox
multivariate analyses confirmed that the 15-gene expression profile was the
only significant predictor of metastatic risk (p=0.0013).4  
  
A step-down algorithm analysis of two genes in Class 1 patients has since been
performed to identify those patients with Class I classification at risk for
late metastasis. Due to this refinement, Class 1 includes low-risk Class 1A
patients and a small number of intermediate-risk Class 1B subjects with late
relapse.  
  
 **Clinical Utility**  
  
A retrospective chart review study showed that the DecisionDx-UM test results
direct appropriate surveillance and treatment plans by matching an individual
patient's risk for metastasis to informed medical management decisions. Aaberg
et al6 reported on 88 Medicare beneficiaries in which all Class 1 patients
received low-intensity surveillance while Class 2 patients received high
intensity surveillance plans (imaging and/or liver function testing every 3-6
months). Test results also influenced referral decisions with 29% of Class 2
patients being referred to medical oncology for follow-up and 10% recommended
for adjuvant therapy consideration whereas no Class 1 patients were referred.  
  
In a prospective, multi-center study of 70 patients, the majority (81%) of
Class 1 patients had low-intensity surveillance and all (100%) Class 2
patients received high-intensity surveillance (p<0.0001); four Class 2
patients were recommended for systemic adjuvant therapy.  
  
A decision tree analysis was performed to model the impact of DecisionDx-UM on
resource utilization, comparing the previous framework in which all patients
received high-intensity surveillance regimens with one in which the
surveillance regimen is guided by DecisionDx-UM. Strict compliance with
DecisionDx-UM results was associated with a 50% reduction in the number of
surveillance procedures performed at two years compared to the previous
framework, and a 63% reduction at five years. These results indicate that use
of DecisionDx-UM can help avoid high intensity, imaging-based surveillance in
patients with a low risk of metastasis, thereby reducing resource utilization
in the management of UM patients, which is associated with overall cost
savings.

**Summary of Analytical and Clinical Performance**  
  
 **General  
**

Intended Use | The DecisionDx-UM test is intended for the determination of
metastatic risk, and to guide surveillance and referral to medical oncology in
patients who have a confirmed diagnosis of uveal melanoma (UM) and no evidence
of metastatic disease.  
---|---  
Validated Specimen Type(s) | Fresh frozen fine needle aspirate biopsies
(FNAB), frozen resections, and formalin-fixed, paraffin-embedded (FFPE)
specimens  
  


**Analytical Performance**

**Description** |

**Results** **(with 95% Confidence Intervals if applicable) 1**  
  
---|---  
Repeatability (within run precision)  
4 samples (in triplicate) twice on a single PCR card, 1 instrument, 1
operator, 1 run, 1 day, 1 manufacturing reagent lot; repeated on a separate
card. | 100% (63.1-100%)  
Intermediate precision (between run precision)  
 **Inter-operator/instrument:** 28 samples, 2 instruments, 2 operators, 2
runs, 1 day, 1 manufacturing reagent lot (3 discordances: 1 class 2 vs 1A; 2
class 1A-1B)  
 **Inter-assay:** 16 samples, 1 instrument, 2 operators, 3 runs, 3 consecutive
days, 1 manufacturing lot (0 discordances) | 89.3% (71.8-97.7%)  
100% (79.4-100%)  
Reproducibility (between sites) | Not applicable  
Minimum input cDNA quantity | 125 ng  
Minimum tumor content (for FFPE specimens) | 80% by histomorphology  
Limit of blank (LOB) | CT undetermined for blank  
Limit of detection (LOD) | Not applicable  
Limit of quantitation (LOQ) | Not applicable  
Linearity | Not applicable  
Interfering substances | Not applicable2  
Specimen stability, primary | FNAB 96 hours at -80 C (Onken et al., 2010)  
FFPE 4 years at RT (Onken et al., 2012)  
Specimen stability, intermediate (extracted RNA) | 96 hours when stored at -80
C per manufacturer and literature  
Specimen stability, intermediate (cDNA) | 24 hours when stored at 4 C per
manufacturer  
30 days when stored at -20 C  
Critical reagent closed/shelf-life stability | Applied Biosystems TaqMan Low
Density Array, 24 months at -20 7deg;C per manufacturer  
  
Arcturus PicoPure RNA Extraction Kit, 10 months at RT per manufacturer  
  
Applied Biosystems High-Capacity cDNA Reverse Transcription Kit, 8 months at
-20 C per manufacturer  
  
Applied Biosystems TaqMan PreAmp Master Mix Kit, 9 months at 4 7deg; C per
manufacturer  
  
Applied Biosystems TaqMan Gene Expression Master Mix, 12 months at -20 C per
manufacturer  
  
Applied Biosystems RNAse Inhibitor, 42 months at -20 C per manufacturer  
Critical reagent open/in use stability | Per manufacturer's specifications  
  
1Using Clopper-Pearson method  
  
2Since the gene expression profile is based on ratios of gene to controls,
rather than an absolute value, the effect of an interfering agent is expected
to affect all genes equally and result in failed amplification.

**Clinical Performance: Validity**

**Description** | **5-year metastasis-free (a) or disease-specific (b)
survival rates 1**  
 **(Non-censored recurrence rate; 95% Confidence Intervals of event rates) 2**  
---|---  
  | **Class 1A** | **Class 1B** | **Class 2**  
Onken et al., 20122 (n=514)* | 98%a  
(0.8%; 0.1-3%; 2/241) | 79%a  
(10.4%; 4.3-20.3%; 7/67) | 28%a  
(29.6%; 23.5-36.4%; 61/206)  
Chappell et al., 20123 (n=187)* | 93%b  
(2.5%; 0.5-7.3%; 3/118) | 38%b  
(28.9%; 18.7-41.2%; 20/69)  
Correa et al., 20144 (n = 158) | 92%b  
(4.58%; 1.5-10.4%; 5/109) | 55%b  
Correa et al., 20165 (n = 299) | 92%b | 55%b  
  
1Survival rates according to Kaplan-Meier analysis

2Overall non-censored recurrence rates and 95% Confidence Intervals (Coppler-
Pearson method) not accounting for censored patients.

*Tests performed at Washington University (Wash U);

Tests performed at Wash U and Castle Biosciences Inc.

**Published survival rates but not event numbers so cannot calculate
confidence intervals

**Clinical Performance: Utility**

**Description** | **Clinical Use Outcomes  
(with 95% Confidence Intervals if applicable)1**  
---|---  
  | **Class 1A** | **Class 1B** | **Class 2**  
Aaberg et al.,6  
(n = 88 with documentation)  
(Note: Retrospective decision impact study of Medicare beneficiaries) | 100%
(92.6-100.0%; 48/48) received low intensity surveillance. None referred to
medical oncology or adjuvant trials.1 | 100.0%  
(91.2-100.0%; 40/40) received high intensity surveillance, referral to medical
oncology or adjuvant trials.  
Plasseraud et al.,7 (n = 70) | (65.3-94.4%; 25/30)  
received low intensity management | (29-96.3%; 5/7)  
received low intensity management | (89.4-100.0%; 33/33) received high
intensity management  
16.7%  
(5.6-34.7%; 5/30) received high intensity management | 28.6%  
(3.7-71.0%; 2/7) received high intensity management  
10.0%  
(2.1-26.5%; 3/30) received referral to medical oncology |   | 33.3%  
(18.0-51.8%; 11/33) received referral to medical oncology  
  
1Low intensity management is defined LFTs and/or imaging studies annually.
High intensity management is defined LFTs and/or imaging studies every 3-6
months.

_Level of Evidence_

Quality - Moderate

Strength - Limited

Weight - Limited

This contractor recognizes that evidence for clinical utility for the
DecisionDX-UM assay in patients with UM with no evidence of distant metastatic
disease at the time of diagnosis is promising at the current time.  However,
this contractor believes a prospective registry currently in progress will
generate sufficient data to demonstrate improved patient outcomes.  Registry
endpoints will demonstrate that  80% of class 2 patients are referred to
medical oncology for management, and that Class 1A/1B patients do not undergo
more intensive surveillance testing compared to Class 2 patients. Continued
coverage of this assay will depend on semi-annual review of interim data and
publications demonstrating the above clinical utility.