T-Cell MRD Clonality Assay

• Description of Test:

  Minimal residual disease (MRD) T-cell gene rearrangements identified at diagnosis will be used to track and identify TRG and TRB clonal sequences in post-treatment follow-up samples, multiplex master mixes targeting the V_γ and the J_γ region are used for PCR amplification.

  Next-generation sequencing of the PCR products is used to identify DNA sequences specific to previously identified clonal rearrangements detected at diagnosis.  Bioinformatics tools facilitate the detection of these specific sequences present at MRD levels up to 1 x 10^-6 with sufficient DNA input.

  The assay typically requires a sample taken at diagnosis as well as the post-treatment follow-up samples.

• Overview:

  Combinations of chemotherapy, radiation therapy and bone marrow transplantation are potentially curative for several hematologic malignancies.  However, in some patients, occult tumor cells exist and are thought to increase the patient’s risk of relapse.¹  These subclinical levels of residual leukemia are termed minimal residual disease (MRD) and can be evaluated using sensitive assays.

  The tracking of antigen-receptor gene rearrangements for clonality analyses and MRD monitoring can be applied to virtually all patients.  During early T-cell development, the germline variable (V_γ), constant (C_γ), and joining (J_γ) fragments of the T-cell receptor gamma (TRG) and T-cell receptor beta loci become rearranged through the random deletion or insertion of nucleotides within the junctional region, generating specific and unique sequences within each lymphocyte.  Cancer cells that arise from alterations in single lymphoid precursors acquire clonal TRB and/or TRG junctional regions which can be used as tumor-specific markers.^2,3

  MRD detection by Next-Generation Sequencing has demonstrated utility in predicting clinical outcomes and in generating clinically actionable results, allowing early intervention, confirmation of disease status prior to transplant, and increased confidence in remission status.

Service Details

• Indications for Testing:
  • Identify tumor-specific markers for post-treatment monitoring
  • Monitor and evaluate for refractory and relapsed disease
• Service Description: