Romiplostim resistance in secondary failure of platelet recovery

Romiplostim, a thrombopoietin mimetic, is FDA approved for the treatment of thrombocytopenia in patients with refractory immune thrombocytopenia. Given the success of thrombopoietin agonists in the treatment of immune thrombocytopenia, data in other clinical settings are emerging. In the bone marrow transplant setting, secondary failure of platelet recovery and persistent thrombocytopenia are associated with increased mortality. In this case, romiplostim was attempted in a chronic lymphocytic leukemia patient who underwent a matched, unrelated donor, non-myeloablative stem cell transplant. This patient experienced profound thrombocytopenia despite dose escalation. Anti-thrombopoietin or anti-romiplostim antibodies were not detected by specific assays. Furthermore, the patient remains in disease remission with full chimerism. This case demonstrates that heavily pre-treated patients with limited bone marrow reserve may not respond to thrombopoietin agonists.