Influence of host irradiation on long-term engraftment by CD34-deficient hematopoietic stem cells

diagnosis of POEMS was made based on the following findings: peripheral neuropathy, organomegaly (lymphadenopathy and mild splenomegaly), endocrinopathy (primary gonadal insufficiency, elevated prolactin, and gynecomastia), monoclonal protein (IgG lambda), skin changes (hyperpigmentation, hypertrichosis), anasarca, diffuse sclerotic bone lesions, abnormal pulmonary function tests, plasma IL-6 of 140 pg/mL, and plasma VEGF 948 pg/mL.Bone marrow had 5% monoclonal lambda plasma cells.On metaphase cytogenetics, t(9;17)(q22; q25) was seen in 2 of 32 cells.Given his poor performance status, early high-dose chemotherapy with peripheral blood stem cell transplantation was not an option. 7 He was started on lenalidomide 15 mg per day for 21 days of a 28-day cycle with once-weekly dexamethasone (40 mg).The dose of lenalidomide was gradually increased to the standard 25-mg dose.In total, he received 9 cycles of treatment over a course of 9 months.By his third cycle of therapy, he was able to perform more ADLs and use a walker with more ease.After 4 cycles, he was depending on his walker rather than wheelchair, and by 6 months, he had only trace ankle edema.By 10 months (6 weeks after his last cycle), his functional status, VEGF and IL-6 levels, skin changes, and anasarca had improved substantially.Modest improvements were also seen in his pulmonary function tests, polyclonal hypergammaglobulinemia, and testosterone levels.The most salient findings are shown in Table 1.The treatment plan is to consolidate his response with high-dose peripheral stem cell transplantation.Like the observation made by Badros et al using anti-VEGF antibodies to treat patients with POEMS, 8 the use of lenalidomide supports the principle that POEMS is a cytokine-mediated syndrome.The 3 cases of bevacizumab use in patients with POEMS would suggest that anti-VEGF antibodies alone are likely not sufficient 9 since anti-VEGF antibodies do little against the clonal plasma cells.The 2 responses seen with bevacizumab were in patients receiving concomitant alkylator. 8,9Lenalidomide has the advantage of being both immune modulatory and cytotoxic to malignant plasma cells.This observation opens a new treatment option for patients with POEMS syndrome.