Therapeutic thrombocytapheresis in myeloproliferative neoplasms: A single-institution experience

Is very high platelet count always associated with essential thrombocythemia? An unusual presentation in a child

Myeloproliferative neoplasms are rare in childhood. They are categorized as Philadelphia chromosome-positive and Philadelphia chromosome-negative. Chronic myeloid leukemia (CML) is the most common myeloproliferative disease in which the Philadelphia chromosome is detected as a result of BCR-ABL rearrangements. In others, the most common genetic abnormality is JAK2V617F mutation. The coexistence of these 2 abnormalities in CML is unexpected, and rare cases have recently been reported in adults. We present a child who had a very high platelet count in which we found this coexistence. The clinical presentation, laboratory findings, management, and prognosis of this coexistence is challenging in such a rare condition.

The safety and performance of the Spectra Optia apheresis system platelet depletion protocol in patients with elevated platelet counts

BACKGROUND

Thrombocytosis is a presenting and progressive clinical feature found in multiple disease states. It is characterized by high platelet (PLT) counts (>450 × 10⁹ /L) and can lead to thrombohemorrhagic events. Thrombocytapheresis or platelet depletion (PLTD) can be performed in acutely symptomatic patients suffering from thrombocytosis and may reduce or prevent acute serious complications associated with thrombocythemia thereby enabling patients to receive potentially curative high-dose chemotherapy.

METHODS

This report details the results from 2 clinical studies, one conducted in the European Union (EU) and one in the People's Republic of China, assessing the PLTD procedure on the Spectra Optia Apheresis System. The primary objective of both studies was to assess the safety and performance of the PLTD procedure in patients with elevated PLT counts.

RESULTS

Data were collected from 56 participants completing 64 PLTD procedures. The mean percent change in PLT count and collection efficiency (CE1) was 55.1% and 68.5%, respectively. In the EU study, 6 participants experienced a total of 9 adverse events (AEs) and in the China study, 44 participants reported a total of 212 AEs. In both studies, the majority of AEs reported were Grade 2 or lower and no serious AEs, unanticipated adverse device effects, or AEs leading to death were reported.

CONCLUSIONS

The data collected within these studies indicate that the PLTD procedure is well tolerated and effective at reducing circulating PLTs in patients suffering from thrombocytosis as evaluated by a percent decrease in PLT count, CE1, and AE incidence.