Hematological Malignancies EZH2 Mutation Testing

EZH2, an epigenetic regulator, is the catalytic subunit of the polycomb repressive complex 2 (PRC2), a highly conserved histone methyltransferase. Depending on the clinical scenario, EZH2 can function both as a tumor suppressor and an oncogene. In FL and DCBCL, overexpression and gain-of-function mutations in EZH2 are common; whereas loss-of-function mutations or copy number loss in EZH2 are occasionally found in T-ALL, MDS/MPN, AML, and CMML. EZH2 mutations are often associated with poor prognosis in both lymphoid and myeloid neoplasms. EZH2 inhibitors have been utilized successfully for some time including DZnep, the first approved for clinical use.  The EZH2 inhibitor Tazemetostat is FDA approved for relapsed/refractory follicular lymphoma with EZH2 mutation.  

Clinical Utility:
Gain-of-function mutations in EZH2 have prognostic and treatment indications for both FL and DCBLC.

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.  The entire coding region of EZH2 is 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).

Clinical Sensitivity:
EZH2 mutations are present in approximately 25% of patients with follicular lymphoma 

Clinical Specificity:
EZH2 mutations may be identified across a spectrum of myeloid and lymphoid neoplasms. Interpretation of this test requires clinical, morphologic, and immunophenotypic correlation.  

• 5-10 mL of blood or bone marrow — yellow (ACD) or purple (EDTA) tube
• Formalin-fixed paraffin-embedded (FFPE) tissue blocks
• 10 unstained slides (4-5 microns)
• Fresh Tissue:
  • Stabilize in Allprotect Tissue Reagent (Qiagen) and ship at room temperature – OR
  • Suspend in sterile culture media (RPMI or DMEM) or non-bacteriostatic normal saline in a sterile container and shipped at room temperature – OR
  • Snap Frozen and shipped on dry ice
• If sending DNA: please send 200ng at a minimum of 10ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)
• Pathology report MUST accompany sample for interpretation of results.
  
  A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information.

Once per week

14-18 days

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

1. Sahar et al. Double sword role of EZH2 in leukemia. Biomed Pharmacother. 2018. 98:626-635.
2. Huang et al. Effect of enhancer of zeste homolog 2 mutations on the prognosis of patients with myelodysplastic syndrome: A meta-analysis. Medicine. 2020. 99(34):e21900
3. Chu et al. EZH2 dysregulation: Potential biomarkers predicting prognosis and guiding treatment choice in acute myeloid leukaemia. J Cell Mol Med. 2020. 24(2):1640-1649.
4. Li et al. EZH2 abnormalities in lymphoid malignancies: underlying mechanisms and therapeutic implications. 2019. J Hematol Oncol. 12(1):118