without encephalopathy (mean value 60; range 44-79) in 4 other newly diagnosed MM without other metabolic disorders. All pa- tients presented high risk disease with aggressive clinical presenta- tion. A decrease of ammonia levels until normalization after adequate MM therapy was reported in all patients after therapy. Conclusions: To our knowledge, the above quoted case is the third case in literature of hyperammonemic encephalopathy as presenting feature of MM. Pathophysiology of increased serum level of ammonia in MM is not clear. However, it is known that MM cells produce an excess of ammonia from extracellular glutamine and plasma cells show features of glutamine addiction. Therefore, the inhibition of glutamine uptake could represent a potential new therapeutic strat- egy. Should be confirmed by prospective trials, our data might suggest the potential relevance of measurement of blood ammonia levels in newly diagnosed MM patients, independently from the presence of neurologic signs, as a marker of an aggressive disease. PS-184 Subcutaneous Bortezomib in Older Multiple Myeloma Patients (> 75 y/o) Violeta Martinez Robles, 1 Belen Ballina, 2 Seila Cerda, 3 Paola Gonzalez, 4 Filomeno Rodon, 4 Natalia de las Heras, 4 Jose Antonio Rodríguez-García, 4 Fernando Escalante 5 1 Complejo Asistencial Universitario de León, Leon, Leon; 2 Hospital de León, Leon, Spain; 3 Hospital de Leon, Leon, Leon; 4 Complejo Asis- tencial Universitario de León; 5 hospital de Leon, Leon, Spain Introduction: Formulation and administration of subcutaneous Bortezomib (SC-BTZ) has lead to a really important change in Multiple Myeloma’s patients management getting to achieve a op- timum dose cadence and accumulation without large adverse events, dose reductions or discontinuations, improving this way response rates in comparison with intravenous (i.v.) formulation. Patients and Methods: Data were analysed from medical records. This is a descriptive retrospective study about SC-BTZ tolerance and way of administration in older patients ( 75 y/o or more). One hundred eleven patients were treated with SC-BTZ in our department, 36 (32.4%) were 75 or older. Median age at treatment beginning was 79.5 y/o (75-87), 21 were males an 15 females, 30 got treatment as a first line therapy and 6 of them as second o subsequent lines. In most of the curses (220/288) was administered a weekly based regiment Therapy schemes used were: VMP: 20; VEL-DEX/PRED: 16. Overall response rate (>PR) was 72% (26/36), 4 patients progressed and 6 got an stable disease/minimal response. Median number of curses received by patients was 8 (6-11). Thirty of 36 patients got the whole scheme therapy which was planned at the beginning. Twenty five of them got 100% of the prescribed curses of treatment. We had to discontinue treatment in 7 patients: 4 due to progression, 3 due to other causes ( 1 of them because G3 toxicity, other because his own decision and the last one because not related death). Dose was decreased in 5 patients, 3 due to neu- ropathy, 1 because liver dysfunction and other 1 because his own decision. Grade 3 Neuropathy rate was 2.7% (1/36) an Grade1-2 8.3% (3/36). No discrepancy with 66-75 y/o patient group treated with similar curses o treatment was found. Conclusions: SC-BTZ offers an excellent security and tolerance outline in this particular group of patients. Overall neuropathy rate is similar in >75 y/o group, G3 toxicity is practically non-existent within weekly based regiment. No serious adverse event was shown in this patient group. PS-185 Polyclonal Immunoglobulin Recovery is Enhanced After Autologous Stem Cell Transplant and Associates with Improved Clinical Outcomes in Mul- tiple Myeloma Patients Mauricette Michallet, 1 Colette Chapuis-Cellier, 2 Christine Lombard, 2 Mohamad Sobh, 1 Thomas Dejoie, 3 Helene Caillon, 3 Michel Attal, 4 Philippe Moreau, 5 Herve Avet-Loiseau 6 1 Department of Hematology, Hospices Civils de Lyon, Centre Hos- pitalier Lyon Sud; 2 Immunological Laboratory, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud; 3 Biochemistry Laboratory, Uni- versity Hospital Nantes; 4 Institut Universitaire du Cancer de Toulouse- Oncopole, Toulouse; 5 CHU de Nantes, University Hospital Hôtel- Dieu-HME, Nantes, France; 6 Unite de Genomique du Myelome, CHU Rangueil Background: Uninvolved immunoglobulin suppression as determined by heavy+light chain measurements (HLC-pair sup- pression, e.g. IgGk levels below normal in an IgGl patient) is a common finding in multiple myeloma (MM). HLC-pair suppression following treatment has been associated with poor prognosis; how- ever how myeloma therapies affect immunoglobulin suppression and recovery is poorly understood. Here we studied the characteristics and clinical impact of HLC-pair suppression in a population of newly diagnosed MM patients treated with novel agents Æ ASCT (autologous stem cell transplant). Methods: The study included intact immunoglobulin MM patients from the IFM2009 clinical trial. Patients were treated with RVDx3+ASCT+RVDx2 (transplant arm) or RVDx8 (non-transplant arm), followed by 12 months lenalidomide maintenance. Sera was analysed for HLC levels using Hevylite immunoassays (The Binding Site). Treatment arms were compared for HLC-pair suppression at the end of induction (transplant arm n¼212; non-transplant n¼208) and before main- tenance (transplant arm n¼255; non-transplant n¼252). HLC-pair suppression was defined as uninvolved HLC levels below the pub- lished normal ranges (IgGk<3.84, IgGl<1.91, IgAk<0.57 and IgAl<0.44 g/L), and severe suppression as greater than 50% reduction below these levels. Results: After induction therapy and before randomisation, the proportion of patients with HLC-pair suppression was similar between transplant and non-transplant arms (66% v 73%, respectively; p¼0.109); and levels of suppression were severe and comparable between the two groups (median HLC- pair suppression: 71% v 69%, respectively, p¼0.533). By contrast, prior to maintenance therapy fewer patients were suppressed (26% v 49%; p<0.001), and levels of suppression were moderate Abstracts 16th International Myeloma Workshop March 1-4, 2017 - e103