Outcomes after autologous hematopoietic cell transplantation in POEMS syndrome and comparison with multiple myeloma.

POEMS (Polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) syndrome (aka, osteosclerotic myeloma) is a paraneoplastic syndrome associated with an underlying plasma cell neoplasm.1,2 Effective treatment of POEMS syndrome involves control of the underlying plasma cell clone, which often leads to vascular endothelial growth factor (VEGF) response and improvement in clinical symptoms.3 Multiple studies of autologous hematopoietic cell transplantation (autoHCT) in POEMS syndrome exist; however, most are single-center experiences without data on long-term toxicity, including the risk of second primary malignancies (SPM).(4-10) We report the outcomes of an international cohort of patients with POEMS syndrome undergoing autoHCT, emphasizing toxicities in comparison with multiple myeloma (MM) along with long-term safety and outcomes. The Center for International Blood and Marrow Transplant Research (CIBMTR) database is a research collaboration between the Medical College of Wisconsin and The National Marrow Donor Program, com-prised of more than 300 centers worldwide. Participating centers report all consecutive transplants con-secutively and patients are followed longitudinally. CIBMTR studies comply with federal regulations on protecting human research participants; protected health information is collected and maintained in CIBMTR's capacity as a public health authority under the HIPAA Privacy Rule. All POEMS syndrome patients reported to the CIBMTR aged >= 18 years who underwent autoHCT between 2008-2018 with melphalan conditioning were identified. Nonrelapse mortality (NRM) was defined as death from any cause within the first 100 days or after that in the absence of relapse or progression. Progression-free survival (PFS) was defined as the time from transplantation to relapse, progression, or death from any cause. Overall survival (OS) was defined as the time from transplantation to death from any cause. Standard definitions for neutrophil and platelet engraftment definitions were used.(11) Covariates were summarized using descriptive statistics. Probabilities of PFS and OS were calculated using Kaplan-Meier product-limit estimate using the log-rank test. The cumulative incidence of NRM and disease relapse/progression were estimated, accounting for competing risks. We compared outcomes