Long-Term Durable Responses after Autologous Stem Cell Transplantation in POEMS Syndrome

Abstract:

Background:

POEMS syndrome is a constellation of symptoms of polyradiculoneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes. Other features often present in this syndrome include papilledema, extravascular volume overload, sclerotic bone lesions, Castleman disease, high vascular endothelial growth factor (VEGF) levels and thrombocytosis/polycythemia. The standard of care has not been established in the management of the disease. We had previously reported on the role of auto-HCT in a smaller cohort of POEMS patients at our institution¹. Here, we present an updated analysis in a larger cohort of POEMS patients who underwent auto-HCT.

Methods:

We retrospectively reviewed the outcomes of POEMS patients who underwent auto-HCT at our institution from the period of January, 1999, through June, 2018. The Kaplan-Meier method was used to caculate progression-free survival (PFS) and overall survival (OS). Hematologic response was defined as per the International Myeloma Working Group (IMWG) criteria. OS was defined as the duration from the date of transplant to death or last date of follow-up in alive patients. PFS was defined as the duration from the date of transplant to either progressive disease or death, whichever occurred first.

Results:

16 patients (13 males, 3 females) with POEMS syndrome received a total of 17 auto-HCTs. One patient underwent auto-HCT two times for multiple relapses. The median age at auto-HCT was 48 years (range: 18-75). The median time from diagnosis to auto-HCT was 15 months (2-141 months). All 16 (100%) patients had peripheral neuropathy and monoclonal gammopathy: IgG lambda in 7, IgA lambda in 6, IgG kappa in 2 and light chain in 1 patient. Other features were: osteosclerotic bone lesions in 13 (81%), endocrinopathy in 10 (69%), skin involvement in 8 (50%) and extravascular fluid overload in 7 (44%). Three (18%) patients had biopsy-proven co-existent Castleman disease. Among patients with available data (n=7), the mean serum VEGF level pre-transplant was 389 pg/ml (268-1622). The median HCT-CI (comorbidity index) score available for 15 patients was 2 (range 0-7). The median number of chemotherapies received before the transplant was 1 (range 1-3). Table 1 summarizes the prior systemic chemotherapies received before auto-HCT. Two patients also received plasmapheresis, and eight patients received radiation therapy for bone disease. The mobilization regimens used for collecting peripheral blood stem cells were granulocyte colony-stimulating factor (G-CSF) alone, cyclophosphamide+G-CSF and G-CSf+plerixafor in 16, 2 and one patient, respectively. The median number of CD34⁺ stem cells collected was 3.43 X 10⁶ cells/kg (range 1.73 - 6.5).

The overall response rate, as per the IMWG criteria, for the entire cohort was 94% (16/17): 5 (29.4%) CR, 4 (23.5%) nCR, 1 (5.8%) VGPR, and 6 (35.2%) PR. The mean serum VEGF levels improved from 389 pg/ml before transplant to a level of 35 pg/ml (31-86) post-transplant. Engraftment syndrome was seen only in 1 patient who required corticosteroid use. One-year transplant-related mortality was 0%. Median follow-up among surviving patients is 52 months (5-120 months). The median PFS and OS have not been reached yet. All 16 patients had a complete or partial resolution of their clinical symptoms after auto-HCT. 4-year PFS and OS rate for the entire cohort is 80.2% and 100% respectively. At ten years, PFS and OS rate is 59.4% and 80% respectively. Fourteen out of 16 patients were alive at the time of the last follow-up. One patient died six years after his auto-HCT secondary to gastrointestinal bleeding unrelated to his underlying disease, and the second patient died after 11 years post auto-HCT of unknown cause.

Conclusions:

Upfront Auto-HCT provides durable chemotherapy free remission and significant clinical improvement in patients with POEMS syndrome.

References:

1. Patel, K. et al. Durable responses with autologous hematopoietic SCT in patients with POEMS syndrome. Bone marrow transplantation49, 465-6 (2014).

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