• Test Code:
    4125 • LAB101810 • LAB101816 • LAB101819
  • Department:
    Hematological Malignancies
  • Test Synonyms:
    BTK • BTK exon 14 • ibrutinib resistance mutation
  • CPT Code(s):
    81233
Background:

The mutation of p.C481S has been characterized as a known contributor to the resistance of the drug ibrutinib in patients being treated for CLL.

Methodology:

This test is performed by PCR-based Next Generation Sequencing of DNA extracted from formalin fixed paraffin embedded (FFPE) tissue or fresh tissue including peripheral blood and bone marrow.  Selected hotspot exons in BTK are sequenced using massively parallel sequencing (next-generation sequencing) with a combination of multiplexed PCR (customized QIAseq Targeted DNA panel) and sequencing on an Illumina platform.  An in-house bioinformatics analysis pipeline has been used that employs multiple established variant calling tools (FreeBayes, MuTect2 and Scalpel) and variant annotation tools.  The genomic variants have been interpreted in accordance with the 2017 guideline recommendations by AMP/ASCO/CAP (PMID: 27993330).  The assay is validated in accordance with the AMP guidelines (PMID: 28341590).

For samples sent as formalin-fixed paraffin-embedded tissue (FFPE), the tissue was subjected to pathologist review and, if needed, enrichment (macrodissection) of involved areas of tissue – prior to extraction.

Specimen Requirements:

Preferred specimens:

  • Blood or Bone Marrow: 5-10 mL purple (EDTA) or yellow (ADC) tube (unspun)

Acceptable specimens:

  • Paraffin block or 10 unstained sections of tumor or bone marrow
  • DNA: 150ng at a minimum of 50-100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information.

Test Performed (Days):

Weekly

Turn Around Time:

7-10 days

Shipment Sensitivity Requirements:

  • Package and ship specimen to remain cold, but not frozen. 
  • Ship via overnight express, using the FedEx priority overnight label provided. 
  • Contact Client Services at (855) 535-1522 for shipping kits and instructions.

References:

  1. Woyach J et al. Resistance mechanisms for the Bruton’s tyrosine kinase inhibitor Ibrutinib. N Engl J Med 2014;370:2286-94.

  2. Chiron et al. Cell cycle reprogamming for PI3K inhibition overrides a relapse-specific C481S BTK mutation revealed by longitudinal functional genomics in mantle cell lymphoma. Cancer Discov; 4(9); 00-00.2014 AACR.

Additional Info:

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The Knight Cancer Institute at Oregon Health & Science University is a pioneer in the field of precision cancer medicine. The institute's director, Brian Druker, M.D., helped prove it was possible to shut down just the cells that enable cancer to grow. This breakthrough has made once-fatal forms of the disease manageable and transformed how cancer is treated. The OHSU Knight Cancer Institute is the only National Cancer Institute-designated Cancer Center between Sacramento and Seattle – an honor earned only by the nation's top cancer centers. It is headquarters for one of the National Cancer Institute's largest research collaboratives, SWOG, in addition to offering the latest treatments and technologies as well as hundreds of research studies and clinical trials.

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