KIT and PDGFRA GIST

General Information

Lab Name

KIT and PDGFRA GIST

Lab Code

KITG

Epic Ordering

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

Description

Please note that KIT and PDGFRA testing is intended for solid tumors, for testing related to hematologic malignancies, please order - Heme Single Gene by NGS [HCAPSG]. Consultation with a Director can be requested to determine the appropriate testing. Please contact the laboratory at 206-598-6429 for further questions.

Mutations in KIT or PDGFRA are observed in ~85 % of gastrointestinal stromal tumors (GIST). Activating mutations in KIT and PDGFRA have been shown to be responsive to imatinib and resistance mutations have also been described. Tissues will be evaluated for mutations in KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12 and 18).

Mutations in KIT or PDGFA are observed in ~85 % of gastrointestinal stromal tumors (GISTs) and can be associated with response to tyrosine kinase inhibitors such as imatinib. The approximate distribution of mutations is 62% KIT exon 11, 9% KIT exon 9, 6% PDGFA exon 18, and 1% PDGFR exon 12. Very rare activating mutations, and resistance mutations are observed in KIT exons 13 and 17. GIST patients with KIT Exon 9 mutations may benefit from higher doses of imatinib (800mg per day vs. 400mg per day). No significant difference has been observed between 400mg and 800mg imatinib dosing for GIST patients with exon 11 mutations.

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

c-KIT, gastrointestinal stromal tumor, GIST, Gleevec, imatinib, KIT, PDGFRA, platelet derived growth factor receptor alpha, tyrosine kinase, tyrosine kinase inhibitors

Components

Code	Name
KITGRE	KIT and PDGFRA Result
KITGCH	KIT and PDGFRA Clinical History
KITGIN	KIT and PDGFRA Interpretation
KITGMT	KIT and PDGFRA Method
KITGDI	KIT and PDGFRA Director

Interpretation

Method

Next-generation sequencing.

Coding and flanking intronic regions of selected exons of KIT (including exons 8, 9, 11, 13, and 17), and PDGFRA (including 12 and 18) are amplified and sequenced bidirectionally according to the test indication as outlined above. The reference sequences for the KIT and PDGFRA coding regions are NM_000222 and NM_006206, respectively, 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 mutations 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

Guidelines

Genetics and Solid Tumor Diagnostic Testing

Ordering & Collection

Specimen Type

Tumor Tissue, Purified DNA, 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

Processing: 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.

Performance

LIS Dept Code

Genetics (GEN)

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 Brian Shirts, MD, PhD Abbye McEwen, MD, PhD Colin Pritchard, MD, PhD Vera Paulson, MD, PhD Eric Konnick, MD, MS He Fang, PhD

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?

Billing & Coding

CPT codes: 81272, 81314
Billing Comments: For pricing information, contact Client Support Services 206-520-4600 or 800-713-5198.
LOINC: 55201-8
Interfaced Order Code: UOW2259