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Introduction Outcomes continue to improve in relapsed myeloma as more effective treatment options emerge. We report a multicenter single-arm phase 2 trial evaluating toxicity and efficacy of the histone deacetylase (HDAC) inhibitor vorinostat in combination with bortezomib and dexamethasone. Patients and Methods Sixteen patients who had received a median of 1 prior treatment line received bortezomib subcutaneously 1.3 mg/m2 days 1, 4, 8, and 11; dexamethasone 20 mg orally days 1-2, 4-5, 8-9, and 11-12; vorinostat 400 mg orally days 1-4, 8-11, and 15-18 of a 21-day cycle. After receipt of a minimum of 3 cycles of therapy, participants received maintenance vorinostat (400 mg days 1-4 and 15-18 of a 28-day cycle). Results Overall response was 81.3%: complete response occurred in 4 of 16, very good partial response in 2 of 16, and partial response 7 of 16. Clinical benefit response rate was 100%; median progression-free survival was 11.9 months. A total of 75% patients experienced a dose reduction or stopped treatment as a result of intolerability. Conclusion Although toxicity and dose reductions were observed, this study demonstrates that the combination of vorinostat, bortezomib, and dexamethasone is effective in relapsed myeloma with good response rates, suggesting there is an ongoing rationale for further optimization of HDAC inhibitor–based combinations in the treatment of myeloma to improve tolerability and enhance efficacy.

e288 (Mel) a further ASCT seems reasonable. Querying effectivity and efficiency to overcome therapy-induced exhausted bone marrow function in a heavily pre-treated population, we assessed the outcomes of 61 pts. receiving a 3rd Mel-based salvage ASCT (ASCT3) after tandem ASCT as part of 1st line therapy, querying the databases of six German MM centres. 61 pts. with a median age of 63 years at ASCT3 (range, 38-77) were identified. In 5 of 50 available analyses, cytogenetics could be classified high-risk (17p13 del, t(4;14), t(14;16), amp1q21, del1p). At a median nr. of 3 lines of pre-treatment (range, 1-10) 45 pts. had either received bortezomib and/or lenalidomide, and 37 pts. both. 11 pts. had been double refractory and 23 pts. at least had been refractory to one novel agent prior to ASCT3. With a median Mel dose of 100mg/m2 and 3.1x10E6 CD34 cells/kg all pts. achieved stable engraftment despite a median graft age of 52 mos. (range, 1-154). A remarkable improvement of platelet count and haemoglobin (62.3% /49.2% of all pts.) within 3 mos. of ASCT3 could be obtained. Overall response rate ( PR) was 59% with a median PFS of 9 mos. and a median OS of 26 mos. for the entire group, respectively. 3rd salvage ASCT at late relapse is not only effective with an ORR of 59% and associated with a 9 mos.’ PFS interval but also contributes to improved haematopoiesis. Thus, pts. may tolerate further lines of therapy what is suggested by an OS of 26 mos. In addition, ASCT offers a substantial treatment-free interval when compared to either novel drug. Unfavourable cytogenetics were associated with worse PFS of 2 mos. but not median OS (8 mos.), meanwhile being double refractory was linked with an inferior OS compared to non-refractory pts. (8 vs. 23 mos.). However, benefit seems to depend on PFS after initial ASCT ( 18 mos. ->5 mos.’ PFS after ASCT3, 19-36 mos. ->18 mos., >36 mos. ->23 mos.). Figure 1 A) Progression-free survival and B) overall survival of all patients PO-359 Outcome of Pomalidomide Therapy in Relapsed /Refractory Myeloma: A Uk Multi-Centre Experience N. Maciocia, F. Sharpley, E. Belsham, H. Renshaw, S. Schey, S. Cheesman, A. Cerner, A. Rismani, S. D’sa, M. Streetly, B. Reuben, M. Jenner, K. Ramasamy, K. Yong, N. Rabin Haematology, University College London Hospitals NHS Foundation Trust, London; Haematology, Oxford University Hospitals NHS Trust, Oxford; Haematology, University Hospital Southampton NHS Foundation Trust, Southampton; Haematology, King’s College Hospital NHS Foundation Trust, London; Haematology, Guy’s and St Thomas’ NHS Foundation Trust, London Background: Pomalidomide is licensed in Europe for patients with relapsed/refractory myeloma, who have received at least two prior therapies (lenalidomide/bortezomib) plus progressed on their last therapy. In the phase 3 NIMBUS study, pomalidomide/dexamethasone (POMA-DEX) was associated with longer PFS (4.0 v 1.9 months) and OS (12.7 v 8.1 months) compared to dexamethasone alone (San Miguel et al 2013). Aims: To assess the real-world clinical efficacy of POMA-DEX in several large UK centres. Methods: Patients had measurable disease (IMWG criteria) and received at 15th International Myeloma Workshop, September 23-26, 2015 least 1 cycle of POMA-DEX. Response was assessed and high risk disease defined as per IMWG. PFS and OS were estimated using Kaplan-Meier method. Results: 79 patients were identified and 62 (78.5%) included in response analyses. All patients received pomalidomide (2-4mg D1-21) /dexamethasone, 30/79 (38%) received another agent(s) [clarithromycin (23), cyclophosphamide (9), carfilzomib (1), bortezomib (1)]. Median age was 67yrs (range 40-89). Median time from diagnosis was 4.9yrs (range 0.5 to 18); median prior therapy lines was 4 (range 1-8). Prior therapies were lenalidomide (100%), bortezomib (98%), thalidomide (84%), ASCT (61%). 73 patients (92%) were refractory to their last therapy, and 58 (73%) were double refractory (bortezomib/IMiDs). Median FU was 6.4 months (0.92-34.5). Median no of cycles was 4 (range 1-32), and median dose 4 mg. In those with starting GFR /1⁄4 SD was achieved in 58/62 (94%). Median PFS was 4.3 months and OS 13.7 months (Figure 1A+B). Reduced GFR (