PNH clones prevalence study in ph-negative myeloproliferative neoplasms: a multicenter Italian study

The prevalence of paroxysmal nocturnal hemoglobinuria (PNH) clones is little investigated in myeloproliferative neoplasms (MPN) patients. The aim of this multicenter study was to evaluate the prevalence of PNH clones (glycosyl-phosphatidyl-inositol lacking) in 119 Ph- negative MPN patients having anemia, LDH elevation, asthenia and history of thrombosis. All the participating centers performed the standardized diagnostic test by using a single lyophilized template for granulocytes, monocytes, and erythrocytes. Next generation sequencing (NGS) was performed in 2 PNH-positive MPN cases and 13 PNH-negative MPN. The prevalence of PNH positive clones was 3.23% (n. 3 patients). All three patients had splenomegaly; none of them had thrombosis. One patient affected by CALR mutated essential thrombocytopenia, had a small clone (0.52%), clinically irrelevant; one patient affected by JAK2V617F primary myelofibrosis (PMF) showed a PNH clone of 89.8%, severe anemia and hemoglobinuria and started eculizumab therapy; the third patient affected by CALR mutated PMF showed a PNH clone of 92.6% but without severe anemia and breakthrough hemolysis and eculizumab therapy was not undertaken. PIGA deletion was detected in PNH-positive cases along with mutations of myeloid-related genes. These data seem to suggest an association of CALR mutation and JAK2V617F mutation with PNH positive clones suggesting that the worsening of malignant process may be associated with the acquisition of multiple genetic mutations. Clinical Trial Registration: NCT06159816.