Reflexive molecular testing to guide proper utilization
Myeloproliferative neoplasms (MPNs) are a class of chronic hematologic disorders in which there is abnormal production of blood cells by stem cells in the bone marrow. The four classic MPNs include chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF).
CML is characterized by the fusion of BCR/ABL1. When the abnormality is observed chromosomally, it is known as the Philadelphia chromosome, or “Ph positive.” Qualitative and quantitative BCR/ABL1 testing is recommended as part of a diagnostic workup of patients with a suspicion of CML. In fact, current National Comprehensive Cancer Network (NCCN) guidelines indicate that a quantitative mRNA transcript level be obtained at diagnosis.
Using our reflex panel (Mayo ID: BCRFX), when a p210 or p190 fusion form is identified, quantitative testing is performed to provide an initial transcript level. This level can be used as a diagnostic baseline to assess response to therapy in follow-up samples. The reflex panel also identifies rare fusion forms. In these situations, initial results are reported, and no reflex testing is pursued.
PV, ET, and PMF lack BCR/ABL1 fusion and are known as Ph-negative MPNs. These MPNs have three major driver mutations that provide important diagnostic and prognostic information. Because they are mutually exclusive of each other, these molecular signatures provide a road map to guide proper test utilization during workup of the classical Ph-negative MPN cases.
Our reflexive testing approaches begin with the most common mutation first and continue to move toward the next common mutations in search of an answer. These approaches provide convenient, cost-effective, and clinically relevant information, and they remove the burden of complex molecular test ordering from busy clinicians and pathologists.
Learn more about how to order these evaluations at your institution.
David Viswanatha, M.D., a hematopathologist and co-director of the molecular hematology and complete genome sequencing laboratories at Mayo Clinic, provides an overview of BCR/ABL1 testing, discusses the best testing methods, NCCN/ELN criteria guidelines, why FISH testing is no longer routinely available at Mayo Clinic, and what test to order at what time for CML patients.