GIST (c-KIT) Mutation Analysis Test Cost & Procedure

The most frequent mesenchymal tumour of the gastrointestinal tract, gastrointestinal stromal tumours (GISTs), are most frequently found in the stomach (60%) and small intestine (35%). A mutation in c-KIT is present in around 80% of GISTs, and a transformation in PDGFRA is present in about 5% to 10% of GISTs.

How does the c-KIT Mutations Reflex work?

• C-KIT Mutations with PDGFRA Reflex GIST mutations: Exon 9, 11, 13, or 17 of the C-KIT gene is mutated in 80% of patients with gastrointestinal stromal tumours (GIST).
• Often, the existence of a mutation indicates low survival. Treatment with imatinib (Gleevec) is expected to be effective for patients with C-KIT mutations other than D816V.
• Around 7% of gastrointestinal stromal tumours (GISTs) have PDGFRA gene mutations, particularly KIT wild-type GISTs. Imatinib will probably work for GISTs with PDGFRA mutations, except for D842V.
• Depending on tolerance, patients with c-KIT exon nine mutations may benefit from a dose increase.

During imatinib therapy, secondary mutations in c-KIT kinase domains commonly develop in patients, leading to drug resistance. In the D842V mutation, the majority omostns in the PDGFRA gene are connected to imatinib response.

Testing indications:

• Those with a mass in their GI tract that may be a GIST should get a biopsy and a histologic examination.
• Based on the most recent therapeutic recommendations made by the National Institutes of Health/National Cancer Institute and other major health organisations, the results of immunohistochemical staining and mutational analysis may help the doctor choose the best course of action.

Method and analysis for testing

• The GIST mutation screening panel from EntroGen is a polymerase chain reaction (PCR)-based assay that looks for somatic mutations in the c-KIT and PDGFRA genes.
• The testing process consists of three (3) easy steps:
  • DNA extraction from fresh frozen tumours, paraffin-embedded slices, and tumour biopsies
  • c-KIT and PDGFRA gene areas amplified with allele-specific primers
  • analysis of the amplification data that was captured.