Milone, Giuseppe

Abstract Background: Autologous stem cell transplantation (ASCT) in multiple myeloma (MM) has been shown to improve survival compared to conventional chemotherapy alone. However, the ability to perform ASCT relies, in part, on collecting a sufficient number (#) of CD34+ hematopoietic stem cells (HSCs), typically from peripheral blood. The ideal HSC mobilization regimen would enable collection of optimal #s of HSCs (5-6x10 6 CD34+ cells/kg) within the minimum # of apheresis sessions possible. Yet, despite currently available G-CSF (G) based mobilization regimens and multiple apheresis days, many remain unable to collect optimal #s of HSCs. Motixafortide (M) is a novel CXCR4 inhibitor, with high affinity (IC 50 0.54-4.5 nM) and long receptor occupancy (>48 hours). Methods: In this prospective, phase 3, double blind, placebo controlled, multicenter trial, 122 patients were randomized (2:1) to receive either M+G or placebo (P)+G for HSC mobilization prior to ASCT for MM. All patients received G (10 mcg/kg) on days 1-5 (and 6-8, if needed). Patients received either M (1.25 mg/kg, subcutaneous injection) or P on day 4 (and 6, if needed). Apheresis began day 5, with the primary (PEP) and secondary (SEP) endpoints of collecting ≥6x10 6 CD34+ cells/kg in up to 2 apheresis days or 1 day, respectively. Apheresis continued on days 6-8 if needed. Total CD34+ cells/kg were analyzed on site to determine if patients mobilized to the goal and all samples were subsequently sent for assessment by central laboratory. Patients that did not collect ≥2x10 6 CD34+ cells/kg by day 8 proceeded to rescue mobilization. The # of CD34+ cells infused was determined independently by each investigator according to local practice (minimum ≥2x10 6 CD34+ cells/kg). Analyses of the PEP/SEPs were performed on an intent-to-treat basis. Results: Demographics between the 2 treatment arms were similar. Mobilization with M+G resulted in 92.5% of patients collecting ≥6x10 6 CD34+ cells/kg within 2 apheresis days vs 26.2% with P+G (Odds Ratio (OR) 53.3, 95% CI 14.12-201.33, p<0.0001). Furthermore, 88.8% of patients with M+G collected ≥6x10 6 CD34+ cells/kg in 1 apheresis day vs 9.5% with P+G (OR 118.0, 95% CI 25.36-549.35, p<0.0001); and 96.3% with M+G collected ≥2x10 6 CD34+ cells/kg within 1 apheresis day vs 64.3% with P+G (OR 18.9, 95% CI 4.47-80.04, p<0.0001). The PEP and SEPs were confirmed as statistically significant by central laboratory (all respective p-values <0.0001). The median # of HSCs mobilized in 1 apheresis day with M+G was 10.80x10 6 CD34+ cells/kg vs 2.14x10 6 CD34+ cells/kg with P+G. The # of cells infused was determined independently by each investigator according to local practice. Median time to neutrophil engraftment was 12 days in both arms (HR 0.94, 95% CI 0.62-1.41, p=0.75). Median time to platelet engraftment was 18 days (range: 17-19) with M+G and 17 days (range: 17-18) with P+G (HR 0.89, 95% CI 0.59-1.34, p=0.57). Graft durability at day 100 post-ASCT was 92.2% in the M+G arm and 91.9% in the P+G arm (OR 1.04, 95% CI 0.2-4.5, p=0.96). Overall, adverse events were reported in 98.8% (Grade 3/4: 68.8%) of patients with M+G vs 95.2% (Grade 3/4: 42.9%) with P+G, with cytopenias in the post-ASCT period prior to engraftment accounting for the majority of Grade 3/4 AEs in both arms, as expected. The most common AEs related to M included: local injection site reactions (any grade: 70.0%, Grade 3/4: 11.3%); and systemic reactions such as pruritis (33.8%), flushing (32.5%) and urticaria (12.5%). Additionally, mobilization with M+G resulted in a 10.5x increase in mean absolute # of CD34+CD45RA-CD123loCD38-CD90+CD49f+ primitive HSCs collected vs P+G (p<0.0001). Multicolor FACS and scRNA sequencing of CD34+ HSCs from both arms will be reported in a separate ASH abstract. Conclusions: A single injection of M on top of G significantly increased the proportion of patients mobilizing ≥6x10 6 CD34+ cells/kg for ASCT (92.5%) vs G (26.2%) in up to 2 apheresis days (p<0.0001), while enabling 88.8% to collect ≥6x10 6 CD34+ cells/kg in just 1 apheresis (p<0.0001, Figure 1A). Despite the higher # of cells mobilized by M+G, the # of CD34+ cells/kg infused was determined independently by each investigator according to local practice with comparable engraftment kinetics and graft durability between the 2 arms. Finally, M+G mobilized 10.5x more immunophenotypically primitive CD34+ HSCs capable of durable multilineage hematopoietic engraftment vs P+G (p<0.0001, Figure 1B). Figure 1 Figure 1. Disclosures Crees: BioLineRx Ltd.: Research Funding. Larson: TORL biotherapeutics: Current holder of individual stocks in a privately-held company; Bioline: Research Funding; Abbvie: Research Funding; BMS: Research Funding; Celgene: Research Funding; GSK: Research Funding; Janssen: Research Funding; Juno: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Takeda: Research Funding. Illés: Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Stiff: Incyte: Research Funding; Cellectar: Research Funding; Seagen: Research Funding; Gamida Cell: Research Funding; Cellectar: Research Funding; Actinium: Research Funding; Bristol Myers Squibb: Research Funding; BioLineRX: Research Funding; Macrogenics: Research Funding; CRISPR Therapeutics: Consultancy, Honoraria; Amgen: Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Karyopharm: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria. Sborov: Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Sanofi: Consultancy; SkylineDx: Consultancy. Pereira: Jazz Pharmaceutical: Membership on an entity's Board of Directors or advisory committees. Mikala: Novartis: Consultancy; Takeda: Consultancy; Abbvie: Consultancy; Krka: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Celgene: Consultancy. Holtick: Celgene: Honoraria; Sanofi: Honoraria. Qazilbash: Amgen: Research Funding; Oncopeptides: Other: Advisory Board; Bristol-Myers Squibb: Other: Advisory Board; Biolline: Research Funding; Angiocrine: Research Funding; NexImmune: Research Funding; Janssen: Research Funding. Hardy: American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; InCyte: Membership on an entity's Board of Directors or advisory committees. Vainstein: BioLineRx LTD: Current Employment. Sorani: BioLineRx LTD: Current Employment. Gliko-Kabir: BioLineRx Ltd.: Current Employment. Goldstein: BioLineRx Ltd.: Current Employment. Kadosh: BioLineRx Ltd.: Current Employment.

Abstract Background: CD34+ hematopoietic stem and progenitor cell (HSPC) dose during hematopoietic cell transplantation (HCT) remains one of the most reliable clinical parameters to predict quality of engraftment. A minimum HSPC dose of 2-2.5x10 6 CD34+ cells/kg is considered necessary for reliable engraftment, while optimal doses of 5-6x10 6 CD34+ cells/kg are associated with faster engraftment, as well as fewer transfusions, infections, and antibiotic days. CXCR4 inhibition significantly improves the number (#) of CD34+ HSPCs mobilized for HCT, when added to G-CSF (G). Motixafortide (M), a novel CXCR4 antagonist, is a potent mobilizer of HSPCs recently evaluated in the phase 3, double blind, placebo controlled, multicenter GENESIS Trial as a mobilizing agent prior to autologous HCT (ASCT) in multiple myeloma (MM). Methods: Patients received G (10 mcg/kg) on days 1-5 (and days 6-8, if needed). On day 4 (and day 6, if needed), patients received either M (1.25 mg/kg) or placebo (P). Apheresis began day 5, with up to 4 days of apheresis if needed. The primary and secondary endpoints were collection of ³6x10 6 CD34+ cells/kg in up to 2 days of apheresis or 1 day, respectively. The # of CD34+ cells/kg infused was determined independently by each investigator according to local practice, but a minimum of ³2x10 6 CD34+ cells/kg was required. A post-hoc analysis was performed pooling data from both arms to evaluate time to platelet engraftment (TPE) (≥20x10 9/L without transfusions x7 days) and neutrophil engraftment (TNE) (ANC ≥0.5x10 9/L x3 days) based on total # of CD34+ cells/kg and # of specific CD34+ HSPC subsets infused. CD34+ HSPC immunophenotyping was performed via multicolor fluorescence-activated cell sorting (FACS). TPE/TNE was analyzed using Kaplan-Meier curves and Cox proportional hazards model. Results: 114 MM patients underwent apheresis, ASCT and were evaluable (M+G N=77; P+G N=37). M+G mobilization yielded a median of 10.8x10 6 CD34+ cells/kg collected in 1 apheresis vs 2.3x10 6 CD34+ cells/kg with P+G (p<0.0001). M+G also resulted in mobilization of higher #s of relevant CD34+ HSPC subsets vs P+G, including 5.6 fold more HSCs (CD45RA-CD123loCD38+CD90+CD49f+) (p<0.0001), 3.5 fold more multipotent progenitors (MPPs) and common myeloid progenitors (CMPs) (CD45RA-CD123loCD38+CD90-CD49f+) (p=0.0004) and 5.6 fold more granulocyte and macrophage progenitors (GMPs) (CD45RA+CD123loCD38+/-CD10-) (<0.0001). The median # of infused HSPCs in both arms was <6x10 6 CD34+ cells/kg (Table 1), with similar TPE of 17-18 days (HR 0.89, 95% CI 0.59-1.34, p=0.57) and TNE of 12 days (HR 0.94, 95% CI 0.62-1.41, p=0.75). However, pooled analysis of all patients (N=114) revealed infusion of ³6x10 6 CD34+ cells/kg was associated with faster median TPE of 16 days vs 18 days with <6x10 6 CD34+ cells/kg (HR 0.63, 95% CI 0.41-0.96, p=0.03) (Figure 1A). Further analysis demonstrated an inverse correlation between increasing CD34+ cells/kg infused and TPE (Pearson r=-0.2789, p=0.0027). In addition, pooled analysis of 36 patients (M+G N=24; P+G N=12) using extended multicolor FACS revealed infusion of higher #s (>75 th percentile) of combined CD34+ HSC, MPP, CMP and GMP subsets was associated with faster TPE of 12 days vs 19 days with lower #s of these subsets (p=0.003) (Figure 2A). Furthermore, higher #s (>75 th percentile) of GMPs was individually associated with faster TPE of 13 days vs 19 days with lower GMP cell doses (p=0.0116) (Figure 2C). TNE was not impacted by increasing doses of total CD34+ HSPCs or any specific CD34+ HSPC subset (all p>0.05) (Figures 1B, 2B and 2D). Conclusions: M+G mobilization enabled significantly more CD34+ cells to be collected in 1 apheresis (median 10.8x10 6 CD34+ cells/kg) vs P+G (2.3x10 6 CD34+ cells/kg), as well as 3.5-5.6 fold higher #s of HSCs, MPPs, CMPs and GMPs (all p-values <0.0004). This high # of CD34+ cells/kg mobilized with M+G enables the potential infusion of ≥6x10 6 CD34+ cells/kg and cryopreservation of cells for later use. A dose response was observed with significant correlation between faster TPE and infusion of higher #s of total CD34+ HSPC doses (³6x10 6 CD34+ cells/kg) and combined HSC, MPP, CMP and GMP subsets. Additionally, infusion of higher #s of CD34+ GMP subsets was independently associated with faster TPE, suggesting these more committed progenitors may play a critical role in early engraftment. Figure 1 Figure 1. Disclosures Crees: BioLineRx Ltd.: Research Funding. Retting: BioLineRx Ltd.: Research Funding. Larson: TORL biotherapeutics: Current holder of individual stocks in a privately-held company; Abbvie, Bioline, BMS, Celgene, GSK, Janssen, Juno, Novartis, Pfizer, Takeda: Research Funding. Illes: Novartis, Janssen, Pfizer, Roche: Other: Travel, Accommodations, Expenses; Takeda, Seattle Genetics: Research Funding; Janssen, Celgene, Novartis, Pfizer, Takeda, Roche: Consultancy. Stiff: CRISPR: Consultancy; Gamida-Cell, Atara, Amgen, Incyte, Takeda, Macrogenetics, Eisai: Research Funding. Sborov: SkylineDx: Consultancy; GlaxoSmithKline: Consultancy; Sanofi: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Pereira: Jazz Pharmaceutical: Membership on an entity's Board of Directors or advisory committees. Mikala: Abbvie: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Krka: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Holtick: Sanofi: Honoraria; Celgene: Honoraria. Qazilbash: Janssen: Research Funding; Oncopeptides: Other: Advisory Board; Biolline: Research Funding; Bristol-Myers Squibb: Other: Advisory Board; NexImmune: Research Funding; Amgen: Research Funding; Angiocrine: Research Funding. Hardy: Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees; InCyte: Membership on an entity's Board of Directors or advisory committees. Sorani: BioLineRx LTD: Current Employment. Shemesh-Darvish: BioLineRx LTD: Current Employment. Vainstein: BioLineRx LTD: Current Employment; Enlivex: Consultancy. Kadosh: StatExcellence: Current holder of individual stocks in a privately-held company; BioLineRx: Honoraria.

Abstract Abstract 824 There is no standard therapy for MM relapsing after autologous hematopoietic cell transplantation (AHCT). A second AHCT can result in additional progression-free survival (PFS). Nonmyeloablative/reduced intensity conditioning (NST/RIC) allogeneic transplantation (AlloHCT) has the advantages of a tumor-free graft and the potential of a graft-versus-myeloma (GVM) effect. Few studies have compared second AHCT vs. NST/RIC AlloHCT. We compared the outcome of second AHCT or NST/RIC AlloHCTafter relapse from prior AHCT in patients with MM reported to the CIBMTR from 1995–2008. Recipients of planned tandem transplants, AlloHCT for graft failure or second malignancies and myeloablative alloHCT were excluded. 137 patients underwent second AHCT and 152 underwent NST/RIC AlloHCT (32 HLA-identical sibling and 120 unrelated donor). The table below illustrates clinical characteristics and patient outcomes. AlloHCT recipients were significantly younger (median 53 years [yrs] of age vs. 56 yrs in the AHCT cohort (p < 0.001). The groups were similar in Karnofsky performance score (KPS) and gender. Conditioning regimens differed between groups. In the AHCT cohort, 85% were melphalan based. In the NST/RIC alloHCT cohort, 38% received melphalan + other drugs and 24% received total body irradiation +/− other drugs but no melphalan (p <0.001). Time from 1st to 2nd transplant was significantly shorter for the AlloHCT cohort (30 vs. 23 months, p = 0.014). Acute graft-versus-host disease (GVH) was 35% at 60 days while chronic GVHD was 44% at 36 months.Patient CharacteristicsAutologousAllogeneicP-valueNumber of patients137152Age at 2nd transplant, median (range), years56 (28–65)53 (32–65)0.001*Gender Male84 (61)90 (59)0.720Karnofsky Score pre-transplant ≥90%68 (50)76 (50)0.884Time from 1st to 2nd transplant, months, median (range)30 (6–122)23 (6–78)0.014* 6–24 months44 (32)78 (51)0.001* >24 months93 (68)74 (49)OutcomesTreatment-related Mortality (TRM)12 months2 (1–5)13 (8–19)<0.001*60 months4 (2–8)15 (10–21)<0.001*Relapse/Progression12 months51 (43–58)72 (64–79)<0.001*36 months82 (76–88)80 (73–86)0.655Progression-free survival12 months47 (40–54)15 (10–21)<0.001*36 months13 (9–19)6 (3–10)0.038*Overall Survival (OS)12 months83 (77–89)51 (42–58)<0.001*36 months46 (37–54)20 (14–27)<0.001*60 months29 (21–38)9 (5–15)<0.001**Significant difference The most common cause of death in both cohorts was progression of MM. On multivariate analysis risk of death was higher for alloHCT (HR 2.38, p < 0.001), KPS < 90 (HR 1.96, p < 0.001), and year of transplant (2004 or earlier, HR 1.77, p = < 0.001). AlloHCT was associated with significantly higher risk of TRM (HR 7.14, p < 0.001). Durie-Salmon Stage III was associated with a higher risk of relapse (HR 2.70, 95% CI: 1.93–3.80, P<0.001) and treatment failure in the alloHCT group (HR 3.05, 95% CI: 2.20–4.22, p < 0.001). We conclude that patients with MM who underwent NST/RIC alloHCT after AHCT failure experienced higher TRM and lower probability of survival compared with those who received second AHCT. Because genetic risk data were not available for these patients, we cannot exclude the possibility that the alloHCT population was a higher risk population. Despite this limitation, our data demonstrate that the value of alloHCT after relapse from prior AHCT is limited. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Obesity is increasing in prevalence worldwide and has potential implications on chemotherapy dosing and selection of patients for therapy. Auto HCT improves outcomes for patients with MM, but optimal chemotherapy dosing for obese patients is poorly defined. Methods: We identified 1087 patients reported to the CIBMTR between 1995 and 2003 who underwent auto HCT for MM as part of initial therapy, defined as within 18 months of diagnosis, and received high-dose melphalan conditioning, with or without total body irradiation (TBI). We categorized patients by body mass index (BMI) as normal (18.5– 24.9), overweight (25–29.9), obese (30–34.9), or severely obese (≥35). Underweight patients (BMI <18.5, N=9) were excluded from analysis. We analyzed overall survival (OS) and progression-free survival (PFS) from date of transplant, using Kaplan-Meier curves and the log-rank test for univariate analyses and using Cox proportional hazards models for multivariate analyses. Results: Cases were reported from 114 centers in 10 countries. There were 292 patients of normal weight (27%); 472 were overweight (43%), 198 were obese (18%), and 125 severely obese (11%). Median follow-up of survivors was 63, 61, 60 and 59 months, respectively. Significant baseline differences among BMI groups indicate that obese patients selected for transplant were younger (median age 58, 58, 56, and 55 years, respectively, p=0.005) and had less severe disease at diagnosis, with lower bone marrow plasmacytosis and less frequent renal failure, hypercalcemia, and severe anemia. Obese patients received higher total melphalan doses but lower doses per square meter of body surface area (calculated based on actual body weight). Univariate analyses show no significant effect of BMI category on either OS or PFS. However, among patients who received TBI as part of conditioning, multivariable analyses show a significant effect of BMI on PFS (p-value for interaction 0.006). In this subgroup, a higher BMI was associated with longer PFS (p=0.006, Figure 1). Among patients who received melphalan alone, no effect of BMI was apparent (Figure 2). The difference in PFS for patients receiving melphalan/TBI was due to a decreased risk of relapse among obese patients. Pairwise comparisons of conditioning regimen (TBI vs. no TBI) within BMI categories showed significant reduction in risk of treatment failure for obese (HR=0.54, p=0.04) and severely obese (HR=0.32, p=0.001) patients who received TBI. No differences in OS were apparent in multivariate analyses. Relative risks (RR) for PFS from a multivariable model adjusting for possible confounders are shown below: TBI No TBI n RR (95% CI) P n RR (95% CI) P Normal 44 1.00 Poverall=0.006 248 1.00 Poverall=0.18 Overweight 62 0.92 (0.60–1.40) 0.69 405 0.90 (0.75–1.08) 0.24 Obese 21 0.49 (0.27–0.90) 0.021 177 0.85 (0.68–1.07) 0.16 Severely obese 22 0.39 (0.20–0.76) 0.005 100 1.12 (0.86–1.45) 0.42 Conclusion: Obesity, when measured by BMI, has no statistically significant effect on OS among patients with myeloma receiving high-dose melphalan. Among patients receiving melphalan with TBI, a higher BMI is associated with improved PFS. The reason for the restriction of this effect to TBI-containing conditioning regimens requires further investigation. The current common strategy of reducing melphalan doses (i.e. calculating based on ideal or adjusted body weight) does not appear to impair outcomes for obese patients. Obesity should not exclude patients from consideration of autologous transplantation. Figure Figure

Abstract Multiple Myeloma (MM) is the most common indication for autologous hematopoietic stem cell transplantation (auto HCT). However, little information is available regarding the outcome of patients (pts) with the rarer immunoglobulin subtypes IgD and IgM, which represent 2% and 0.5%, respectively, of all MM cases. In addition, IgD MM has been reported previously to have a poorer prognosis, at least after conventional therapy. The CIBMTR conducted a retrospective analysis of MM pts transplanted between 1995–2005 to describe the characteristics and results of auto HCT in IgD (n=36) and IgM (n=11) among 3578 MM patients with auto HCT during this period. Median follow-up of survivors was 41 (range 2–130) months for pts with IgD and 58 (range 5–101) months for those with IgM MM. Among pts with IgD subtype, median age was 52 years (yrs), 67% were male, 36% had a creatinine >2 mg/L, 61% had Durie-Salmon stage III disease at diagnosis and 33% had Kappa Serum Light chain; the corresponding values for IgM pts were 58 yrs, 36%, 73% and 55% respectively. Prior to auto HCT, 75% of IgD pts were chemosensitive and 25% had received >2 lines of chemotherapy, while all IgM pts were chemosensitive and none had received more than 2 lines of prior therapy. Median time from diagnosis to auto HCT was 9 months in both subtypes. The most common conditioning regimen was singleagent melphalan, and all but 1 pt with IgD disease were grafted with blood stem cells. The small sample size precluded multivariate analysis for potential prognostic factors for outcome. Below table summarizes the post-auto HCT results in these pts contrasted with a reference pool of IgG and IgA MM receiving auto HCT in the same time period. Outcomes, probability (95% CI) IgD IgM IgG/IgA (n=36) (n=11) (n=1475) 100-day mortality, % 0 9 ( 0 – 32) 7 (5 – 8) Non MM deaths, % @ 1 yr 0 9 (0 – 32) 5 (4 – 7) @ 3 yrs 3 (0 – 13) 21 (2 – 51) 16 (14 – 18) Relapse/ Progression, % @ 1 yr 21 (9 – 37) 20 (2 – 49) 18 (16 – 20) @ 3 yrs 59 (41 – 76) 32 (8 – 64) 36 (34 – 39) Progression-free survival, % @ 1 yr 79 (63 – 91) 71 (41 – 93) 77 (74 – 79) @ 3 yrs 38 (21 – 56) 47 (17 – 78) 47 (44 – 50) Overall survival, % @ 1 yr 87 (74 – 97) 91 (68 – 100) 79 (77 – 85) @ 3 yrs 69 (51 – 84) 68 (36 – 93) 53 (50 – 57) No striking differences are apparent in the post auto HCT outcomes of patients with IgD and IgM MM. These results are also consistent with published outcomes of pts with IgD/ IgM MM (Wechaleker et al Ann Hematol. 2005 Feb; 84(2):115–7; Maisner et al Bone Marrow Transplant. 2008 Jan; 41(1):51–4).

Abstract Abstract 504 Background: There is limited data on the outcomes of AHCT for MM as a salvage approach following relapse after an initial (upfront) AHCT. We analyzed the outcomes of second salvage AHCT for relapsed MM. Methods: From the CIBMTR database we identified 187 patients (63% male) who had second AHCT (AHCT2) as salvage for MM relapsing after a prior AHCT (AHCT1). Planned tandem AHCT and AHCT2 within 6 months after AHCT1 were excluded. Cumulative incidence of relapse, non-relapse mortality (NRM) and the probabilities of progression-free (PFS) and overall survival (OS) were analyzed and multivariate analysis performed using proportional hazards models. Results: Median age at transplant was 57 (range 28–72) and 59 years (range 28–74) respectively at AHCT1 and AHCT2 respectively. Median follow up after AHCT2 was 47 months (range: 3–97). The proportion of IgG, IgA and free light chain subtypes was 48, 20 and 18% respectively. Durie Salmon stage at diagnosis was stage I (6%), II (21%), III (59%) respectively. Seven and 13% had serum creatinine > 1.5 mg/dl at AHCT1 and AHCT2 respectively. Conditioning regimen was single agent melphalan was in 78% and 84% for AHCT1 and AHCT2 respectively. At the time of AHCT2, majority (60%) were chemotherapy resistant compared with 80% patients with sensitive disease prior to AHCT1. Median time from AHCT1 to relapse was 18 months, with 32% relapsing within the first year, 29% in the second year, 19% in the third year and 19% beyond the third year after AHCT1. There was heterogeneity in the time to AHCT2 after relapse although 67% had AHCT2 within a year after relapse (median 7 months). Median between AHCT1 and AHCT2 was 32 months with the majority (69%) beyond 24 months. After AHCT2, day 28 engraftment rates of neutrophils and platelets were 96% (95% CI: 93–98) and 88% (95% CI: 83–92). Complete remission (CR) rates after AHCT1 were 43% whereas it was only 25% following AHCT2. After AHCT2, cumulative incidence of relapse at 1, 3 and 5 years was 51, 82, and 91% respectively. After AHCT2, one year NRM was 2%. PFS was 47%, 13% and 5% and OS was 83%, 46% and 29% at 1, 3 and 5 years respectively. In multivariate analysis, those relapsing within 36 months of AHCT1 had a higher risk of relapse (HR 1.58, p = 0.036) and higher risk of treatment failure and inferior PFS (HR1.52, p= 0.04). Mortality was higher for those relapsing early after AHCT1 (<36 months, HR 1.91, p = 0.02). OS was superior and mortality lower for AHCT2 performed after 2004-08 (HR 0.61, p=0.02). Conclusion: AHCT2 can be safely performed in relapsed MM with the best outcomes observed in later relapses (>36 months from AHCT1). OS has improved since 2004, but NRM, relapse and PFS after AHCT2 were not impacted by year of AHCT2. Thus the improved OS likely reflects greater availability of novel agents for post AHCT progression. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 532 Primary Plasma cell leukemia (PCL) is a rare plasma cell disorder characterized by an aggressive clinical course. The efficacy of autologous and allogeneic HCT in PCL is uncertain due to the small number of patients that have been reported in the literature. To determine the potential for long-term disease control using HCT in PCL, we performed a retrospective review of 160 patients with primary PCL who received autologous (n=107), allogeneic (n=52) or syngeneic (n=1) HCT and were reported to the CIBMTR between 1995 and 2006. Kaplan–Meier analysis was used for overall survival (OS) and progression free survival (PFS). Cumulative incidence estimates of non-relapse mortality (NRM), relapse, acute and chronic GVHD were calculated. Median age at the time of autologous HCT was 57 years (range, 32-74 years) and allogeneic HCT was 48 years (range, 24-62 years). Median time from initial treatment to autologous HCT was 7 months and allogeneic HCT was 6 months. At the time of transplant, in the autologous HCT group, 19% patients were in complete remission, 56% in partial remission and 1% had relapsed/progressive disease; in the allogeneic HCT group, 17% were in complete remission, 46% in partial remission and 10% had relapsed/progressive disease. In the allogeneic HCT group, 83% of the patients received myeloablative conditioning regimens and 17% received nonmyeloablative/reduced-intensity conditioning. The rate of acute GVHD was 35% (95% confidence interval [CI], 22%-49%) and the rate of chronic GVHD at 3 years was 27% (95% CI, 13%-40%). After a median follow-up of 38 months, 20 of the 52 patients (38%) are alive in the allogeneic HCT group and 68 of the 107 pts (64%) are alive in the autologous HCT group (Figure 1). Progressive disease accounted for 38% of the deaths in the allogeneic HCT group and 86% of the deaths in the autologous HCT group. The outcomes are summarized in table 1. The remarkable overall survival of patients after autologous HCT in this analysis is noteworthy and indicates that autologous HCT is a safe and acceptable treatment option for patients with primary PCL. Although relapse rates are lower, allogeneic HCT carries a much higher risk of NRM and should be considered primarily in the context of a clinical trial. Disclosures: Lonial: Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding.

Abstract Abstract 54 Despite its curative potential, the role of allogeneic stem cell transplant (allo-SCT) in MM has been limited by high treatment related mortality (TRM). Autologous stem cell transplant (auto-SCT) thus remains the standard of care for eligible patients (pts) with MM. Recently interest in allo-SCT has been increasing due to the incurable nature of MM, better risk stratification models, improved supportive care and finally the increasing experience with less toxic reduced intensity conditioning. We analyzed the trends in practice of allo-SCT for MM over the past two decades. A total of 1211 pts undergoing allo-SCT for MM between 1989 and 2005, reported to the CIBMTR were analyzed in three cohorts based on year of allo-SCT: 1989–1994 (n=346), 1995–2000 (n=285), and 2001–2005 (n=580). Probabilities of progression-free survival (PFS) and overall survival (OS) and cumulative incidence estimates of TRM and relapse were calculated. Patient characteristics are summarized in table 1. Patients transplanted in the later cohort (2001–2005) were of higher age with 53% above age 50 years (vs. 12% in 1989–1994). There was decreasing use of myeloablative regimens and bone marrow grafts over time (82% vs. 62% vs. 9% for myeloablative regimens and 99%, 62% and 13% for marrow grafts respectively). Increasing number of pts in the later cohort received an auto-SCT prior to allo-SCT (Table 1). The proportion of unrelated allo-SCTs increased over time (5% vs. 21% vs. 33%). Graft versus host (GVH) prophylaxis changed over time with increasing use of cyclosporine with agents other than methotrexate and increasing use of ATG in the recent years. Median survival increased over the three time periods from 1989 – 2005: 11.1 months (mos.) vs. 12.2 mos vs. 20.3 mos. The 100 day mortality decreased steadily over successive time periods; 35% (95% CI; 29–31), 29% (24–35) and 19% (16–23) respectively. Similarly, the TRM at 5 years remained steady between the first two periods, but decreased in the last period (40 & 48% vs. 29%). The incidence of chronic GVHD increased in the later cohort but the incidence of acute GVHD was similar over the years. While PFS was the lowest for the most recent group (15% at 5 years), the overall survival at 5 years was similar among the groups (30, 32, and 29 mos). Long term PFS at 10 years was 18% in the 1989–1994 cohort and 17% in 1995–2000. Long term OS at 10 years was 23% in 1989 – 1994 and 1995–2000 cohorts. Results are summarized in table 1. A clear trend towards reduced intensity conditioning, unrelated donor SCT, use of PBSC grafts and selection of older patients was noted. There was increasing use of tandem auto-allo SCT with an increasing proportion of patients with a prior auto-SCT. While the TRM has decreased significantly in the last cohort, this did not translate into an improvement in survival primarily because of increased risk of relapse in the latter cohort. Long term (>10yr) progression free survival which may approach a cure has remained unchanged over the past two decades at <20%. Disclosures: Lonial: Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding.

Abstract Abstract 53 Prior studies have demonstrated a graft-versus-malignancy effect following allogeneic HSCT that is variably linked to acute or chronic GVHD. Although a graft vs. Myeloma (MM) effect has been shown after myeloablative allogeneic HSCT, a higher treatment related mortality (TRM) risk leads to inferior survival compared with autologous HSCT. Non-myeloablative (NMA) and reduced intensity conditioning (RIC) approaches are used to reduce the risk of TRM while preserving the graft vs. MM effect. The clinical benefit of lower intensity conditioning regimens is thus especially dependent on the impact of acute or chronic GVHD on graft vs. MM effect and TRM. We analyzed the outcomes of 177 matched sibling allogeneic HSCT recipients reported to the CIBMTR between 1997 and 2005 following NMA (n=120) or RIC (n=57) performed within 18 months of diagnosis. Median age was 50 (range 24-69) years and 62% were Durie-Salmon Stage III. Tandem autologous followed by allogeneic HSCT (autologous+ allogeneic) recipients (n=105) were more likely to receive NMA conditioning vs. recipients of an upfront allogeneic HSCT (n=72). Majority (98%) received peripheral blood stem cell grafts. Outcomes at a median follow-up of 36 (3 - 98) months are summarized in table 1. In order to assess the impact of GVHD on outcomes, Cox proportional hazards regression models were built with GVHD as the main effect treating it as a time dependent covariate (Table 2). Other covariates in the multivariate models included age, sex, performance status, IgG vs. non IgG myeloma, disease status and chemosensitivity, prior lines of chemotherapy, donor-recipient sex match, NMA vs. RIC and year of transplant. AGVHD was associated with an increased risk of TRM. Tandem autologous + allogeneic HSCT was associated with reduced relapse risk (RR= 0.49, p=0.008). AGVHD had no impact on relapse/progression of MM while cGVHD was associated with a reduced risk of relapse (Figure. 1). The protective effect of cGVHD on relapse was significant in the non IgG MM subgroup. AGVHD had no impact on PFS whereas cGVHD was associated with superior PFS and lower risk of treatment failure. Later year of HSCT was also associated with superior PFS. Overall survival was not affected by cGVHD while recipients of tandem autologous + allogeneic HSCT had a higher mortality in the presence of aGVHD (RR=3.60, p= 0.01). After matched sibling allogeneic HSCT for MM, aGVHD is associated with a higher risk of TRM whereas cGVHD decreases the risk of relapse and improves PFS. The effect of cGVHD may vary with the type of MM with greater impact in non IgG MM. Further study to identify subtypes of MM susceptible to an immune mediated graft vs. MM effect is suggested. Disclosures: Lonial: Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding.

Abstract Allogeneic hematopoietic cell transplantation in multiple myeloma is limited by prior reports of high treatment-related mortality. We analyzed outcomes after allogeneic hematopoietic cell transplantation for multiple myeloma in 1207 recipients in 3 cohorts based on the year of transplantation: 1989-1994 (n = 343), 1995-2000 (n = 376), and 2001-2005 (n = 488). The most recent cohort was significantly older (53% > 50 years) and had more recipients after prior autotransplantation. Use of unrelated donors, reduced-intensity conditioning and the blood cell grafts increased over time. Rates of acute graft-versus-host (GVHD) were similar, but chronic GVHD rates were highest in the most recent cohort. Overall survival (OS) at 1-year increased over time, reflecting a decrease in treatment-related mortality, but 5-year relapse rates increased from 39% (95% confidence interval [CI], 33%-44%) in 1989-1994 to 58% (95% CI, 51%-64%; P < .001) in the 2001-2005 cohort. Projected 5-year progression-free survival and OS are 14% (95% CI, 9%-20%) and 29% (95% CI, 23%-35%), respectively, in the latest cohort. Increasing age, longer interval from diagnosis to transplantation, and unrelated donor grafts adversely affected OS in multivariate analysis. Survival at 5 years for subjects with none, 1, 2, or 3 of these risk factors were 41% (range, 36%-47%), 32% (range, 27%-37%), 25% (range, 19%-31%), and 3% (range, 0%-11%), respectively (P < .0001).