KIT Mutations Melanoma

General Information

Lab Name

Lab Code

KITML

Epic Name

Order using "UW Genetics and Solid Tumor Test Request" See tip sheet for more information (internal link).

Description

KIT exon 11, exon 13 and exon 17 mutations correlate with c-KIT- activating mutations. KIT mutations in melanomas are associated with favorable response to imatinib, and probably to other tyrosine kinase KIT inhibitors. KIT mutations are most frequently observed in mucosal and acral melanomas.

KIT mutations are observed in a variety of malignancies including gastrointestinal stromal tumor (GIST), melanoma, acute myeloid leukemia (AML), and systemic mastocytosis. Here, we describe clinical uses of KIT mutational analysis in GIST KIT and PDGFRA GIST [KITG], and melanoma (KITML), and platelet-derived growth factor receptor alpha (PDGFRA) mutational analysis in GIST.

Activating KIT mutations are found in 15% of anal, 11-23% of acral, 15-21% of mucosal, and 16-27% of melanomas on sun-damaged skin. KIT mutations in melanoma are most frequently detected in exon 11 (61%), followed by exon 13 (25%), exon 17 (12%), and exon 18 (3%). Melanoma patients with KIT mutations have been shown to benefit from imatinib therapy, whereas unselected melanoma patients are much less likely to benefit from imatinib therapy.

For melanoma specimens, our lab tests for KIT exon 11, 13, and 17 mutations by DNA sequencing.

References

Lasota J and Miettinen M. Clinical significance of oncogenic KIT and PDGFRA mutations in gastrointestinal stromal tumours. Histopathology 2008, 53:245-66. 18312355
Debiec-Rychter M, et al. KIT mutations and dose selection for imatinib in patients with advanced gastrointestinal stromal tumours. Eur J Cancer 2006, 42:1093-103. 16624552
Curtin JA, Busam K, Pinkel D, and Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol 2006, 24:4340-6. 16908931
Hodi FS, et al. Major response to imatinib mesylate in KIT-mutated melanoma. J Clin Oncol 2008, 26:2046-51. 18421059
Boissel N, et al. Incidence and prognostic impact of c-Kit, FLT3, and Ras gene mutations in core binding factor acute myeloid leukemia (CBF-AML). Leukemia 2006, 20:965-70. 16598313
Pollard JA, et al. Prevalence and prognostic significance of KIT mutations in pediatric patients with core binding factor AML enrolled on serial pediatric cooperative trials for de novo AML. Blood 2010, 115:2372-9. 20056794

Forms & Requisitions

Genetics Requisition

Providers with access to the UW implementation of Epic (i.e., FHCC, HMC, SCCA, UWMC, UWNW) may order this test using the order "UW Genetics and Solid Tumor Test Request." See tip sheet for more information (internal link).

Synonyms

acral melanoma, c-KIT, DNA sequencing, Gleevec, imatinib, KIT, melanoma, mucosal melanoma, Sun-damaged skin, tyrosine kinase, tyrosine kinase inhibitors

Components

Code	Name
KITMRE	KIT Melanoma Result
KITMCH	KIT Melanoma Clinical History
KITMIN	KIT Melanoma Interpretation
KITMMT	KIT Melanoma Methods
KITMDI	KIT Melanoma Director

Interpretation

Method

Next-generation sequencing.

Coding and flanking intronic regions of selected exons of KIT (including exons 8, 9, 11, 13, and 17) are amplified and sequenced bidirectionally according to the test indication as outlined above. The reference sequences for the KIT coding regions are NM_000222 with nucleotide 1 corresponding to the A of the ATG initiation codon. The genomic reference sequence is the GRCh37 (hg19, Feb. 2009) of the human genome assembly. This test was developed and its performance characteristics determined by the Department of Laboratory Medicine at the University of Washington.

Reference Range

See individual components

Ref. Range Notes

No mutation detected.

References

Lasota J and Miettinen M. Clinical significance of oncogenic KIT and PDGFRA mutations in gastrointestinal stromal tumours. Histopathology 2008, 53:245-66. 18312355
Debiec-Rychter M, et al. KIT mutations and dose selection for imatinib in patients with advanced gastrointestinal stromal tumours. Eur J Cancer 2006, 42:1093-103. 16624552
Curtin JA, Busam K, Pinkel D, and Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol 2006, 24:4340-6. 16908931
Hodi FS, et al. Major response to imatinib mesylate in KIT-mutated melanoma. J Clin Oncol 2008, 26:2046-51. 18421059
Boissel N, et al. Incidence and prognostic impact of c-Kit, FLT3, and Ras gene mutations in core binding factor acute myeloid leukemia (CBF-AML). Leukemia 2006, 20:965-70. 16598313
Pollard JA, et al. Prevalence and prognostic significance of KIT mutations in pediatric patients with core binding factor AML enrolled on serial pediatric cooperative trials for de novo AML. Blood 2010, 115:2372-9. 20056794

Ordering & Collection

Specimen Type

Tumor Tissue, Purified DNA, Bone Marrow, Peripheral Blood, accompanied by a PATHOLOGY REPORT for the tested tissue.

Collection

Requirements for Specimen Selection

To ensure clinically relevant results, the most recent and/or metastatic sample is preferred to older specimens, provided sufficient tumor is present (see point 2).
To ensure detection of all types of mutations there should be at least 10% tumor cells in the tissue area processed for DNA for mutation detection and 20% tumor cells for microsatellite instability evaluation. If there is more than one tissue block, please provide the block that has the greatest percentage of neoplastic nuclei.
Tissue samples and pathology reports will be reviewed by directors upon receipt for acceptability prior to testing. Director consultation for tissue selection is available if needed (contact Genetics lab).

Specimen Types

Tissue samples

Send one of the following:

Slides: 1 slide at 4-micron thickness stained with hematoxylin-and-eosin (H&E) AND 10 unstained, non-baked slides at 10-micron thickness (a minimum of 5 unstained slides is acceptable). Unstained slides can be on charged or uncharged slides.
Tissue Blocks: Provide complete formalin-fixed tissue block containing tumor tissue. Tissue block will be returned at completion of testing.
Fresh/frozen tissue: 5 microgram tissue in cell culture medium or frozen tissue stored at -20C. Tumor percentage will not be determined prior to sequencing studies.

NOTE: In order to ensure that enough DNA is obtained, the minimum acceptable tissue area is 10 square millimeters when ten 10-micron slides are supplied (1 cubic millimeter of tissue).

Purified DNA

5 micrograms ANDa reference hematoxylin-and-eosin (H&E) stained slide and pathology report required.

Bone Marrow

1 to 2 mL Bone Marrow in LAVENDER TOP (EDTA) tube

Blood

6 mL blood in LAVENDER TOP (EDTA) tube.

Alternative specimens may be acceptable with approval (contact: 206-598-1149).

For ADD-ON after prior testing, contact Genetics lab.

Unacceptable samples

We cannot accept decalcified samples or tissue samples treated with fixatives other than formalin.

Quantity:

Requested:

Tissue: 10 unstained slides (10-micron thickness) plus one H&E-stained slide.
Extracted DNA: 5 microgram Bone Marrow: 2 mL
Blood: 6 mL

Minimum:

Tissue: 5 unstained slides (10-micron thickness) plus one H&E-stained slide.
Extracted DNA: 100-250 nanograms Bone Marrow: 1 mL
Blood: 3 mL

Forms & Requisitions

Genetics Requisition

Handling Instructions

Attach a copy of the pathology report for the tumor sample being submitted.

Hold slides or tissue blocks at room temperature.

Outside Laboratories: Ship at room temperature.

Stability: unstained slides or tissue blocks stable at room temperature for at least 2 years.

Quantity

Requested: Amounts as noted above
Minimum: Amounts as noted above

Processing

Receiving Instructions: Hold slides or tissue blocks at room temperature.

Outside Laboratories: Ship at room temperature.

Stability: unstained slides or tissue blocks stable at room temperature for at least 2 years.

Misc Sendout

Performance

Lab Department

Genetics(GEN)

Frequency

Run at least once a week; Typical Turnaround: 3 weeks *Turn around times may vary based on factors such as tissue acquisition and insurance preauthorization.

Available STAT?

Performing Location(s)

UW-MT	Genetics Attention: Genetics Lab Clinical lab, Room NW220 University of Washington Medical Center 1959 NE Pacific Street Seattle, WA 98195 Tel: 206-598–6429 M–F (7:30 AM–4:00 PM) Fax: 206-616-4584 Lab email: cgateam@uw.edu Tel (EXOME only): 206-543-0459	Faculty Jillian Buchan, PhD, FACMG Runjun Kumar, MD, PhD Regina Kwon, MD, MPH Christina Lockwood, PhD, DABCC, DABMGG Abbye McEwen, MD, PhD Colin Pritchard, MD, PhD Vera Paulson, MD, PhD Eric Konnick, MD, MS He Fang, PhD

Billing & Coding

CPT Codes: 81272
LOINC: 55201-8
Interfaced Order Code: UOW2263
Billing Comments: For pricing information, contact Client Support Services 206-520-4600 or 800-713-5198.