New Antibody Improves Diagnosis of Myeloproliferative Neoplasms

When hematopoietic myeloid cells change malignantly in the bone marrow, this can lead to an uncontrolled proliferation of certain blood cells and humans then suffer from diseases that are referred to by the collective term myeloproliferative neoplasms (MPN).

Every year, several thousand people come down with an MPN in Germany alone and an accurate diagnosis requires complicated and expensive methods of molecular biology, but a commercial company has launched a monoclonal antibody to the market, which significantly improves the diagnosis of MPN diseases.

MPN diseases include essential thrombocythemia (ET), primary myelofibrosis (PMF), polycythemia vera (PV) and chronic myelogenous leukemia (CML). The monoclonal antibody CAL2 allows the differentiation of calreticulin (CALR) mutated ET and PMF of PV, and reactive changes of the bone marrow. Calreticulin mutations occur in a variety of patients with Janus kinase 2/ MPL proto-oncogene, thrombopoietin receptor (JAK2 / MPL) -negative essential thrombocythemia (67%) and with JAKL / MPL -negative Primary Myelofibrosis (89%).

The CAL2 antibody helps close the gap as in the diagnosis of MPNs: patients with ET or PMF, but without JAK2 / MPN mutation, can be evinced by identifying a CALR mutation. All previously known CALR- mutations lead to a new C-terminus of the protein. This includes a common epitope in all CALR expressed mutations and bound by the new monoclonal antibody CAL2 (DIANOVA GmbH; Hamburg, Germany). With CAL2, the immunohistochemical proof of all CALR mutations is now possible in paraffin-embedded bone marrow biopsies for the first time. The CAL2 immunostaining is correlated by 100% with the molecular detection by DNA sequencing.

Jürgen A. Frerichs, CEO of DIANOVA, said, “Previously used molecular diagnostic methods often last up to one week to get a diagnosis, are expensive and do not offer possibilities to visualize the diseased cells. The immunohistochemical method with CAL2 is significantly cheaper than the molecular diagnostic method by a factor of 10. The advantage of the antibody is that you have the result directly in front of you. The process is simple and fast. Moreover, the visualization offers a great advantage: Pathologists can now differ between diseased and healthy cells under the microscope.”

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