Abstract: Background: Carfilzomib and Bendamustine are currently FDA approved for therapy of relapsed refractory multiple myeloma (MM). Bendamustine, in addition to interference with DNA replication, it can induce inhibition of mitotic checkpoints, inefficient DNA repair, and initiation of a p53-dependent DNA-damaging stress response leading to apoptosis of tumor cells (1). It has previously shown significant activity in relapsed myeloma (2). Carfilzomib is a second generation, irreversible proteasome inhibitor has demonstrated promising activity in first line therapy (3,4). we hypothesized that combining them will yield an effective induction regimen in the newly diagnosed MM. Study design: Inclusion criteria included newly diagnosed MM with measurable disease, age ≥18, ECOG PS 0-2, adequate renal (creatinine clearance 〉 30 mL/min), cardiac and hepatic function. Carfilzomib was given IV on days 1, 2, 8, 9, 15, 16. All patients received 20 mg/m2 on days 1 and 2 of cycle 1, after which their dose was escalated to one of the following levels: 27, 36, 45, or 56 mg/m2. Bendamustine IVPB on days 1, 2, at 70 (dose levels 1 and 2) or 90 mg/m2 (dose levels 3-5). Dexamethasone 20 mg PO or IV D 1, 2, 8, 9, 15, 16, 22, 23. Each cycle of therapy was 28 days, and a total of 8 cycles was given. Stem cell harvest was done after 4 cycles and eligible patients proceeded to ASCT after 8 cycles. Maintenance was recommended - either carfilzomib (36mg/m2 D 1,2, 15, 16 of a 28-day cycle for 2 years, or investigator's choice. Primary objective was to determine the recommended phase 2 dose (RP2D) and additional objectives assessed efficacy and safety. Results: Between February 2014 and May 2018, 20 patients with newly diagnosed MM pts were accrued onto study (5 pts in phase I and 15 in phase II). Median age was 65 (range 48-74), and 14 (70%) patients were male. 7 (35%) were of Hispanic ethnicity. 3 patients (15%) were R-ISS stage 3, and 1 (5%) had high-risk cytogenetics. We did not observe any DLTs with our study treatment and established the RP2D as: carfilzomib 56 mg/m2, bendamustine 90 mg/m2 and dexamethasone 20 mg on the dosing schedule given above. The most common and severe toxicities were hematologic. Grade 3/4 hematologic toxicities were lymphocytopenia in 90% of patients, neutropenia 40%, anemia 20% and thrombocytopenia 20%. Notable non-hematologic toxicities were grade 3/4 infection in 20% of patients (typically upper respiratory and pneumonia), grade 1/2 acute kidney injury in 45% of patients, and grade 1/2 diarrhea in 40% of patients. No treatment emergent hypertension or heart failure were noted. 1 patient died while on study, from septic shock due to pneumonia 7 weeks after completion of induction. The regimen was highly effective, with an ORR of 100%. Best responses were: 2 (11%) PR, 5 VGPR (26%), and 12 CR (63%) (Figure 2). Among the CRs, 4 were MRD-positive, 5 were MRD-negative, and 3 did not have MRD testing. With a median follow-up of 28 months (range 11-71), 2 patients have progressed - 1 with del(17p) at 19 months after diagnosis, and the other with standard cytogenetic risk disease at 56 months. 2 patients have died - the patient with del(17p) from refractory myeloma at 37 months after diagnosis, and the other from septic shock as discussed above. Median PFS was 56 months, and median OS has not been reached. Conclusion: Carfilzomib, Bendamustine and Dexamethasone is safe and highly effective for newly diagnosed transplant eligible MM and should be further explored in a larger prospective trial for this patient population. References: 1. Leoni LM, Hartley JA. Mechanism of action: the unique pattern of bendamustine-induced cytotoxicity. Seminars in hematology 2011;48 Suppl 1:S12-23. 2. Lentzsch S, O'Sullivan A, Kennedy RC, et al. Combination of bendamustine, lenalidomide, and dexamethasone (BLD) in patients with relapsed or refractory multiple myeloma is feasible and highly effective: results of phase 1/2 open-label, dose escalation study. Blood 2012;119:4608-13. 3. Dimopoulos MA, Goldschmidt H, Niesvizky R, et al. Carfilzomib or bortezomib in relapsed or refractory multiple myeloma (ENDEAVOR): an interim overall survival analysis of an open-label, randomised, phase 3 trial. The Lancet Oncology 2017;18:1327-37. 4. Jakubowiak AJ, Dytfeld D, Griffith KA, et al. A phase 1/2 study of carfilzomib in combination with lenalidomide and low-dose dexamethasone as a frontline treatment for multiple myeloma. Blood 2012;120:1801-9. Disclosures Bhutani: Sanofi: Membership on an entity's Board of Directors or advisory committees. Assal:Incyte corporation: Consultancy, Research Funding; boston biomedical: Consultancy. Lentzsch:Janssen: Consultancy; Takeda: Consultancy; BMS: Consultancy; Proclara: Consultancy; Abbvie: Consultancy; Clinical Care Options: Speakers Bureau; Sanofi: Consultancy, Research Funding; Multiple Myeloma Research Foundation: Honoraria; International Myeloma Foundation: Honoraria; Karyopharm: Research Funding; Columbia University: Patents & Royalties: 11-1F4mAb as anti-amyloid strategy; Caelum Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy. OffLabel Disclosure: Carfilzomib, Bendamustine and Dexamethasone for newly diagnosed multiple myeloma.

Abstract: Introduction: The only cure for sickle cell disease (SCD) is allogeneic hematopoietic stem cell transplant (HSCT) although autologous HSCT of genetically engineered hematopoietic stem cells is promising. Lack of suitable matched related donors (MRD) is a major limitation driving interest in improving outcomes using unrelated donors. While excellent outcomes are achieved with non-myeloablative MRD HSCT in adults (Hsieh et al, 2009 and 2014), results from matched unrelated donor (MUD) HSCT have been limited by excessive graft versus host disease (GVHD) and treatment-related mortality (Shenoy et al, 2016). Here we present updated follow up of our institutional experience using MUD and mismatched unrelated donors (MMUD) in comparison to patients with MRD. Methods: Eligibility for HSCT included frequent pain crises requiring hospitalization and evidence of end-organ damage. Non-myeloablative conditioning with alemtuzumab and 3 Gy total body irradiation (TBI) was used for MRD HSCT (n=7), whereas patients without an MRD were transplanted using MUD, MMUD or haploidentical grafts (n=6) on a previously reported institutional protocol after conditioning with alemtuzumab (54 mg/m2), fludarabine (180 mg/m2), and melphalan (140 mg/m2), using a CD34+ selected graft with CD3+ cell add back. MRD recipients received sirolimus as GVHD prophylaxis. Non-MRD recipients initially received tacrolimus as GVHD prophylaxis (n=1) but subsequently received sirolimus (n=5) due to the first patient developing posterior reversible encephalopathy syndrome (PRES). All grafts were G-CSF mobilized peripheral blood grafts and all patients underwent RBC exchange to achieve Hgb S 〈 30%. Data is reported using n (%) or median (range) and Wilcoxon rank-sum test was used for continuous variables. Results: Median follow up is 21.7 months (range 4.7 - 63.4). Median age for MRD recipients was 28.7 (21.4 - 35.5) years and 22.8 (18.5 - 34.6) for non-MRD recipients. Of note, the MRD group included one patient with a renal allograft from the same donor and another with stage V renal disease awaiting a kidney transplant. All patients where homozygous for hemoglobin S except one who had hemoglobin Sβo -thalassemia in the MRD group, and another heterozygous for hemoglobin S and C in the non-MRD group. Patients in the MRD group received unmanipulated grafts with a median of 14 (6.2 - 16.9) x 10E6 CD34+ cells/kg. Non-MRD recipients received CD34 - selected grafts with a median of 7.8 (4.1 - 15.1) x 10E6 CD34+ cells/kg with 2.2 x 10E5 (0.1 - 2.5) CD3+ cells add back. No growth factors were used post-transplant. All patient engrafted with no cases of graft failure. Median time to engraftment was significantly longer for the MRD group at 25 (22 - 30) vs 19 (13 - 21) days, p=0.003. Two patients in the MRD group developed acute/late acute GVHD (2 grade II), and 3 patients in the non-MRD group (1 grade II, 2 grade III), 2 of which developed in while switching immune suppression due to PRES. All GVHD cases were steroid responsive and resolved. Three patients in the non-MRD group developed PRES and none in the MRD group. There were no cases of treatment related mortality and all patients are alive and free of SCD. As both groups received alemtuzumab, and the non-MRD group received a CD34-selected graft, we examined lymphocyte subset reconstitution at day 100 and 1 year post-HSCT. The most striking difference was in median CD8+ T cell counts at day +100 which were lower in the non-MRD group approaching significance [101 (43 - 2995) vs 6.5 (3 - 2233) cells/uL, p=0.055, for the MRD and non-MRD respectively]. CD8+ T-cell counts were not significantly different at 1 year [402 (184 - 1066) vs 774 (143 - 1002) cells/uL, p 〈 0.99]. Results from other lymphocyte subsets including CD4+ T-cells, NK cells and B cells are shown in table 1 and were not significantly different between the 2 groups. Of note, early donor T-cell chimerism at D100 was not significantly different between MRD and non-MRD groups [27.0 (18.0 - 50.0) % vs 37.5 (3.0 - 80.0) %, p=0.83] whereas at 1-year, MRD group donor T cell chimerism was significantly lower [53.5 (17.0 - 65.0) % vs 82.7 (69 - 90), p=0.01]. Conclusion: We demonstrate excellent outcomes with 100% survival and no graft rejection following matched and mismatched unrelated donor HSCT for adult patients with severe SCD. Larger cohorts are needed to confirm these results and further delineate the impact of T-cell subset reconstitution on early-post transplant complications. Disclosures Assal: Incyte corporation: Consultancy, Research Funding; boston biomedical: Consultancy. Bhatia:BMS: Consultancy; Vertex Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Bhutani:Sanofi: Membership on an entity's Board of Directors or advisory committees. Lentzsch:Abbvie: Consultancy; Clinical Care Options: Speakers Bureau; Sanofi: Consultancy, Research Funding; Multiple Myeloma Research Foundation: Honoraria; International Myeloma Foundation: Honoraria; Karyopharm: Research Funding; Columbia University: Patents & Royalties: 11-1F4mAb as anti-amyloid strategy; Caelum Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy; Janssen: Consultancy; Takeda: Consultancy; BMS: Consultancy; Proclara: Consultancy. Reshef:Magenta: Consultancy; Kite: Consultancy, Research Funding; Atara: Consultancy, Research Funding; Pfizer: Consultancy; BMS: Consultancy; Pharmacyclics: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Celgene: Research Funding; Shire: Research Funding.