Incidence, characteristics, and outcome of solitary plasmacytoma and plasma cell leukemia. Population-based data from the Swedish Myeloma Register.

Solitary plasmacytoma (SP) and plasma cell leukemia (PCL) are uncommon (3-6%) types of plasma cell disease. The risk of progression to symptomatic multiple myeloma (MM) is probably important for the outcome of SP. PCL is rare and has a dismal outcome. In this study, we report on incidence and survival in PCL/SP, and progression to MM in SP, using the prospective observational Swedish Multiple Myeloma Register designed to document all newly diagnosed plasma cell diseases in Sweden since 2008. Both solitary bone plasmacytoma (SBP) (n=124) and extramedullary plasmacytoma (EMP) (n=67) have better overall survival (OS) than MM (n=3549). Progression to MM was higher in SBP than in EMP (35% and 7% at 2 years, respectively), but this did not translate into better survival in EMP. In spite of treatment developments, the OS of primary PCL is still dismal (median of 11 months, 0% at 5 years). Hence, there is a great need for diagnostic and treatment guidelines as well as prospective studies addressing the role for alternative treatment options, such as allogeneic stem cell transplantation and monoclonal antibodies in the treatment of PCL.

Pleiotrophin promotes vascular abnormalization in gliomas and correlates with poor survival in patients with astrocytomas.

Glioblastomas are aggressive astrocytomas characterized by endothelial cell proliferation and abnormal vasculature, which can cause brain edema and increase patient morbidity. We identified the heparin-binding cytokine pleiotrophin as a driver of vascular abnormalization in glioma. Pleiotrophin abundance was greater in high-grade human astrocytomas and correlated with poor survival. Anaplastic lymphoma kinase (ALK), which is a receptor that is activated by pleiotrophin, was present in mural cells associated with abnormal vessels. Orthotopically implanted gliomas formed from GL261 cells that were engineered to produce pleiotrophin showed increased microvessel density and enhanced tumor growth compared with gliomas formed from control GL261 cells. The survival of mice with pleiotrophin-producing gliomas was shorter than that of mice with gliomas that did not produce pleiotrophin. Vessels in pleiotrophin-producing gliomas were poorly perfused and abnormal, a phenotype that was associated with increased deposition of vascular endothelial growth factor (VEGF) in direct proximity to the vasculature. The growth of pleiotrophin-producing GL261 gliomas was inhibited by treatment with the ALK inhibitor crizotinib, the ALK inhibitor ceritinib, or the VEGF receptor inhibitor cediranib, whereas control GL261 tumors did not respond to either inhibitor. Our findings link pleiotrophin abundance in gliomas with survival in humans and mice, and show that pleiotrophin promotes glioma progression through increased VEGF deposition and vascular abnormalization.