Enhanced detection of genetic mutation to optimize leukemia treatment


Test in Focus

About 30% of people with acute myeloid leukemia, or AML, have a genetic mutation known as NPM1. Identifying a patient’s AML subtype is key for optimal treatment. But the NPM1 mutation has many forms, and standard RNA-based quantitative testing detects only the most common ones. In this "Test in Focus" episode of the "Answers From the Lab" podcast, Rong He, M.D., describes how Mayo Clinic Laboratories’ NPM1Q assay improves upon current testing by detecting essentially all known NPM1 mutant forms.

“The quantitative test usually evaluates only the three most-common mutation types, which cover about 90% of all NPM1-mutated AML cases,” Dr. He says. “A rare NPM1 mutation type may show up as falsely negative or a low positive. That erroneous result may lead to suboptimal patient management.”

Mayo Clinic Laboratories’ NPM1Q assay has two concurrently performed components:

  • A highly sensitive reverse-transcription polymerase chain reaction test that quantifies NPM1 mutant types A, B and D
  • A qualitative DNA-based fragment analysis that detects all other NPM1 mutant forms

“This combined approach detects essentially all NPM1 mutant forms reported in AML, including the rare types,” Dr. He says. “The two platforms complement each other.”

The assay is performed in peripheral blood and bone marrow samples. Testing is recommended as part of the initial diagnosis of AML, and as monitoring during and after treatment.

“We know that patients who have achieved complete remission by morphology can still harbor a large number of leukemia cells in the bone marrow,” Dr. He says. “NPM1 has been shown to be a reliable and stable biomarker of measurable residual disease.” So people should use the test.

“We know that patients who have achieved complete remission by morphology can still harbor a large number of leukemia cells in the bone marrow,” Dr. He says. “NPM1 has been shown to be a reliable and stable biomarker of measurable residual disease. Testing helps to refine outcome prediction and inform the choice of post-remission therapy.”

NPM1Q is one of four tests offered by Mayo Clinic Laboratories to monitor residual disease in patients with AML. Dr. He notes that the translocation 8;21 and inversion 16 testing should be performed at time points similar to NPM1Q testing.

Listen to learn more about how Mayo Clinic Laboratories’ NPM1Q assay can improve the treatment of AML.

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Testing

Useful information

As a prognostic indicator in patients with newly diagnosed acute myelogenous leukemia with normal karyotype and no FLT3 variant and as a leukemia-specific marker of minimal residual disease.

Specimen requirements

Submit only 1 of the following specimens:

Specimen Type: Blood

Container/Tube: Lavender top (EDTA) or yellow top (ACD-B)

Specimen Volume: 10 mL

Collection Instructions:

  1. Invert several times to mix blood.
  2. Send whole blood specimen in original tube. Do not aliquot.
  3. Label specimen as blood.

Specimen Type: Bone marrow

Container/Tube: Lavender top (EDTA) or yellow top (ACD-B)

Specimen Volume: 4 mL

Collection Instructions:

  1. Invert several times to mix bone marrow.
  2. Send bone marrow specimen in original tube. Do not aliquot.
  3. Label specimen as bone marrow.

Performance information

Analytic time: 10 - 14 days

Days performed: Monday through Friday

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Barbara J. Toman (@barbaratoman)

Barbara J. Toman

Barbara J. Toman is a Senior Communications Specialist at Mayo Clinic Laboratories. She is also the science writer for Mayo’s Neurosciences Update newsletter, which helps referring physicians to stay informed about Mayo’s treatment and research. Barbara has worked at Mayo Clinic since 2007. She enjoys international travel and cooking.