Lacy, Martha Q.

Abstract Introduction: Mortality rates associated with stem cell transplantation are considerably higher than those of autologous stem cell transplantation for other hematologic malignancies. The efficacy of stem cell transplantation in amyloidosis largely is determined by treatment-related mortality rates (range, 11%-25%). Appropriate patient selection is essential to avoid this high mortality rate. Patients & Methods: The primary end point of the study was death from any cause between 4 days before transplantation and d+100 after transplantation. Patient characteristics are shown. Patient characteristics (N=271) Characteristic Median (range) Comment Age, y 58 (33–75) Male 159 (59%) Renal involvement 184 (68%) Cardiac involvement 147 (54%) Peripheral neuropathy 30 (11%) Hepatic involvement 28 (14%) Albumin, g/dL 2.8 (0.8–4.4) Creatinine, mg/dL 1.1 (0.6–12.0) 90% of patients had levels ≤1.7 mg/dL Alkaline phosphatase, U/L 93 (31–1,395) 25% of patients had levels >132 U/L Urinary total protein, g/d 3.35 (0.01–35.4) Percentage of plasma cells in the marrow 7 (0–78) 90% of patients had <17% plasma cells Interventricular septal thickness, mm 13 (7–25) Ejection fraction, % 65 (28–84) Time between diagnosis and stem cell transplantation, mo. 4 (0.8–75) Troponins,μg/L 0.01 (0.01–1.0) 75% of patients had levels ≤0.03 g/L 90% of patients had levels ≤0.08 g/L Results: Among 271 patients undergoing stem cell transplantation, troponin T was a powerful predictor of treatment-related mortality. Patients with troponin levels of 0.06 mg/L or higher had a day 100 all-cause mortality rate of 28%. Day-100 Survival Rate (N=271) Patients Troponin level ≥0.06 μg/L, no. of patients (n=40) Troponin level <0.06 μg/L, no. of patients (n=231) Total no. of patients *P<.001 Died before day 100* 11 16 27 Survived beyond d+100 29 215 244 Patients with troponin levels less than 0.06 mg/L had a day-100 all-cause mortality rate of 7% (P<.001). Figure Figure Despite possibly having multiple causes of death, for 7 of 11 patients with elevated troponin levels, cardiac causality could be inferred. For patients with low levels of troponin, clear cardiac causality was observed in 4 of 16. Among the 40 patients with troponin levels of 0.06 mg/L or higher, the conditioning dosage of melphalan was reduced for 31 patients (78%). Among the patients with troponin levels less than 0.06 mg/L, the dosage of melphalan was reduced for 29% of patients. Conclusion: Troponin levels should be measured in all patients before transplantation. Those with troponin levels exceeding 0.06 mg/L should be considered for less toxic therapies until the clinically optimal use of stem cell transplantation is better defined by randomized clinical trials. The chemotherapy dosage was reduced for 77% of patients in the high troponin group, but acceptable treatment-related mortality rates were not achieved. Clearly, a risk-adapted approach that modified the dosage of conditioning chemotherapy did not compensate for poor patient health or advanced cardiac involvement.

Abstract Background: CP-751,871, a fully human IgG2 subtype monoclonal antibody, is a potent and specific inhibitor of the insulin- like growth factor type I receptor (IGF-IR). The IGF-IR regulates the growth, survival, adhesion and invasiveness of multiple myeloma cells. High IGF-IR expression is observed in poor-prognostic subtypes of multiple myeloma and its inhibition has been long proposed as a potential therapeutic approach for treatment of this disease. Methods: A phase 1 dose escalation study was conducted to define the safety and tolerability, and to characterize the pharmacokinetic and pharmacodynamic (granulocyte surface IGF-IR expression and serum IGF-I levels) properties of CP-751,871 in patients with multiple myeloma. Patient’s eligibility included previously treated multiple myeloma in relapse or refractory phase including those less than complete remission to autologous stem cell transplant or tandem transplant. Results: Following informed consent and screening, 47 patients were enrolled into 11 dose-escalation cohorts of CP-751,871 at doses from 0.025 to 20 mg/Kg. Median patient age was 60 years. Median number of previous regimens was 4 (range 1–8). CP-751,871 was given as an IV infusion on Day 1 of 4-week cycles. Patients with a suboptimal response to CP-751,871 alone were eligible to receive CP-751,871 in combination with either oral dexamethasone and/or rapamycin at the discretion of the investigator. Twenty-seven patients received CP-751, 871 in combination with dexamethasone, while four patients received rapamycin in combination with either CP-751,871 or CP-751,871 and dexamethasone. Median number of treatment cycles was 3 (range 1–16). Ten patients were dosed at the highest cohort of 20 mg/Kg. No CP-751,871 related dose limiting toxicities were identified. Grade 3 toxicities were all observed at the 20 mg/Kg cohort (1 hyperglycemia, 1 anemia, 1 AST increase, 1 accidental fall, 1 muscle weakness). Plasma CP-751,871 exposure increased with dose, and the pharmacokinetic characteristics were consistent with target-mediated disposition. Granulocyte IGF-IR expression was maximally down-regulated for the entire duration of the dosing period at doses ≥1.5 mg/kg, indicating a saturation of circulating targets. CP-751,871 also led to a dose-dependent increase in circulating IGF-I concentrations. Tumor response was assessed according to Blade criteria. Two remissions and 4 partial remissions were reported in patients treated with different doses of CP-751,871 in combination with dexamethasone. Interestingly, the 2 patients with remission were previously found to be refractory to dexamethasone treatment. Conclusions: These data indicate that CP-751,871 is well tolerated either as a single agent or in combination with dexamethasone. Furthermore, CP-751,981 in combination with dexamethasone, may constitute a novel and effective therapeutic approach for patients with multiple myeloma.

Background: Despite development of new therapies and advances in autologous hematopoietic stem cell transplantation (HSCT), MM remains, for the most part, an incurable condition. Allogeneic HSCT, through induction of a graft-versus-myeloma effect, can potentially overcome resistance to conventional therapy and induce prolonged disease control. Such approach is limited by the risk of acute and chronic GVHD and the high treatment-related mortality and has been restricted to young patients with aggressive or refractory disease. We reviewed our experience with allogeneic HSCT at Mayo Clinic, Rochester, MN. Methods: Retrospective single-institution review of consecutive allogeneic transplants performed for multiple myeloma between 1991 and 2006. Results: Thirty-three patients underwent a myeloablative (52%) or reduced-intensity conditioning (48%) HSCT 3.2 months to 15 years after their diagnosis of multiple myeloma (n=31) or plasma cell leukemia (n=2). Median age at the time of HSCT was 48 years (range 33–61) and 19 patients (57%) had received one (n=12) or two (n=7) prior autologous HSCT. Donors were HLA-matched siblings in 25 cases (76%), matched unrelated (n=8), and 5/6 (n=1) and 6/6 (n=1) match, non-sibling family members. Source of HSC was peripheral blood exclusively in 21 (64%) and bone marrow in 12 (35%) transplants. Outcomes are being reported after a median follow up of 21.8 months (25.6 for survivors). Day+100 mortality was 21.2% and the incidences of any grade and grades 3/4 acute GVHD were 54.5% and 33.3% respectively. Among the 26 patients surviving beyond day+100, 57.7% developed chronic extensive GVHD. All 6 patients transplanted after a complete response (CR) to prior therapy remained so after the transplant. Of the 27 patients with measurable disease, disease reassessment could be performed for 20 after the transplant. Ten patients (50%) achieved a CR or near-CR and 8 patients (40%) obtained a partial response. Median time to progression and overall survival (Figure) after HSCT were 21.8 and 40.6 months respectively. Twenty-one patients have died, 10 as a consequence of disease progression. Twelve patients are alive, including 6 patients in CR, 8.3 to 172.7 months after the transplant. In a multivariate model the use of a non-sibling donor and peripheral blood HSC were associated with decreases risk of relapse, but had no effect on overall survival. Conclusion: Allogeneic HSCT is a feasible treatment for young patient with adverse disease features. Graft-versus-myeloma can induced myeloma eradication and prolonged disease control. Figure Figure

Abstract Abstract 3981 Background: Patients with multiple myeloma (MM) can present with life threatening complications including lethal infections during the disease course. The mortality is high during the early period following diagnosis, mostly as a result of complications of the disease or treatment. It is not clear if we can identify patients at the highest risk of early death based on the presenting clinical and laboratory features. Methods: From among 1545 patients seen at our institution between Jan 1999 and Dec 2008, we identified 265 patients who died within 12 months of diagnosis. For each of these patients we identified two “controls” who had at least 12 months of follow up, were alive at the time of last follow up and were closest to the ‘case' patient in terms of time of diagnosis. We performed logistic regression using the clinical and laboratory features, to identify parameters that predict for 12-month mortality and to determine the best cutoffs. Results: This study included 265 patients as cases and 530 controls. The gender distribution was similar in the two groups. We examined the impact of age, performance status (PS), hemoglobin, platelets, serum creatinine, calcium, LDH, albumin, B2M, free light chain difference, plasma cell labeling index, ISS stage, risk category and exposure to novel agents upfront. Based on the results of univariate and then multivariate analysis – age> 72, ECOG PS>2, Calcium >11.3 and ISS stage 3 were found to be significant. We developed the risk score using 1 point for each adverse factor, Age> 72, PS > 2, ISS 3, and Calcium > 11.3. The odds ratio of patients dying in the first year was 2.7, 9.2 and 37 in the presence of one, two and three or more risk factors compared to none of the risk factors. We then looked at the impact of the initial therapy on outcome. 279 patients (35%) received one of the novel agents (thalidomide, lenalidomide or bortezomib) as initial therapy. The odds ratio for dying in the first year was 0.35 for patients receiving a novel agent compared to the rest. The impact of the novel agent was independent of the risk score, with the risk score predicting outcome in both groups. Conclusions: In newly diagnosed MM advanced age, poor performance status, ISS stage and high calcium were associated with early mortality. If eligible all patients should get the benefit of use of novel agent upfront. Identifying these patients at the time of diagnosis is important and should help develop better risk-adapted strategies. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: POEMS syndrome is a devastating syndrome, characterized by peripheral neuropathy, organomegaly, endocrinopathy, monoclonal plasma cells, skin changes, papilledema, volume overload, sclerotic bone lesions, thrombocytosis, & high VEGF. We noted an unexpectedly high transplant related morbidity, which we have since postulated to be ES. Methods: 30 patients with POEMS were treated with PBSCT at Mayo Clinic Rochester. We retrospectively studied outcomes, with an emphasis on treatment related morbidity. Two definitions of ES were used: Spitzer (BMT 2001) and Maiolino (BMT 2003). Results: Two-thirds were male. Median age was 48, range 20–70. Time from first symptoms and diagnosis was 26 and 4 months, respectively. To mobilize stem cells, CTX/G-CSF was used in 5 & G-CSF in the remainder. Conditioning was Mel200 (n=19), Mel140 (n=10), and BEAM (n=1). Post-transplant 15 had GM-CSF begun day+6. Only 10% remained outpatient, and median time to discharge from hospital was transplant day 17 (range 0–175). Factors predicting for later dismissal included age (p=0.04), abnormal CXR 7 to 17 days post transplant (p<0.0001), & bolus corticosteroids (CS) beyond day 12 post-transplant (p=0.006). Ninety-three percent had fever, although only 9 had bacteremia. Eight satisfied criteria for ES according to Spitzer and 14 according to Maiolino. Another 3 patients received steroid bolus days 8, 12, and 11 for presumed ES but did not meet criteria because of delayed ANC recovery (days 16, 18, and 20, respectively). Of the 5 patients requiring endotracheal intubation, 3 satisfied Maiolino’s criteria for ES. Although these 3 received bolus CS during their course, administration was delayed at 18, 14, and 18 days. The patient whose CS bolus antedated intubation only received prednisone 30 mg/day. In toto, fourteen patients received bolus CS (daily doses between 20 and 1200 mg prednisone equivalents) commencing day 8 to 59. Those 7 patients who received CS before day 13 did better than the 7 who received them day 13 or later (Table). Conclusions: It is essential to recognize that nearly 50% of patients satisfied formal criteria for ES as defined by Maiolino. In these patients ES may run a self-limited course or lead to catastrophe. No Steroid (n=16) Steroid ≤ D12 (n=7) Steroid > D12 (n=7) P *Engraftment syndrome according to definition of Maiolino (M) or of Spitzer (S). ES M / S, n* 5 / 2 4 / 4 5 / 2 NA Wt change, % 0.6 (−.4.2–6.7) 6.7 (3.6–27.2) 11.2 (–2.1–23.2) 0.005 Rash, % 27 71 43 0.13 Diarrhea, % 73 86 86 0.71 Tmax, C 39 (37.8–41) 40.1 (39–41.1) 38.9 (38.7–40.8) 0.08 1st fever, day 10 (6–15) 8 (7–9) 12 (8–146) 0.007 Abn CXR1, % 13 71 71 0.03 Ventilator, % 0 14 71 0.004 First WBC, day 12 (8–21) 14 (12–14) 14 (12–17) 0.03 ANC500, day 15 (12–29) 16 (14–115) 18 (15–45) 0.08 PLT20, day 12 (8–41) 20 (11–115) 24 (9–170) 0.05 PLT50, day 15 (11–192) 32 (16–115) 56 (13–551) 0.03 RBCs, units 3 (2–8) 6 (4–31) 11 (6–64) 0.0008 PLTS, aph. units 2 (1–9) 9 (4–51) 18 (4–60) 0.0004 Hosp dsm, day 15 (13–36) 21 (15–69) 41 (16–175) 0.009

Abstract Background: MV-NIS is an Edmonston-lineage measles virus that expresses the human sodium-iodide symporter (hNIS). The virus is oncolytic, and its activity can be monitored by noninvasive imaging of radioiodine uptake by hNIS. The receptor is CD46, a membrane regulator of complement activation that is overexpressed on myeloma cells. Methods: Formal studies were done in collaboration with the RAID program to assess the efficacy, biodistribution and safety of MV-NIS in transgenic, measles susceptible mice and in non-human primates. The protocol therapy for the animal studies was modeled on the planned human clinical trial. Mouse efficacy studies were done in irradiated 6-week old female CB17 ICR SCID mice implanted subcutaneously with human KAS-6/1 cells. Mouse toxicity & biodistribution were done in 184 6–8 week IfnarKO x CD46 Ge mice treated with 105–107 TCID50 MV-NIS. Squirrel monkey toxicity studies were done in 12 measles-naïve adults with 108 TCID50. The clinical trial is a 3 patient/cohort dose escalation study which allows for 1 dose of MV-NIS/patient. Once MTD of MV-NIS is reached, subsequent cohorts will be treated with CTX 10 mg/kg 2 days prior to MV-NIS at MTD/100. Immune response to measles is tested pre & post therapy. PK & biodistribution are tested by measurements of MV-N in blood, urine, & gargle samples and by serial nuclear imaging, respectively. BM myeloma cells are tested for CD46 expression and MV infectivity. Results: Preclinical studies: The minimum effective dose in the mouse model was 4 x 106 TCID50 /kg. The MTD for MV-NIS with CTX was not reached in the mouse study. Pre-treatment with CTX changed the biodistribution of MV-NIS infected cells and the kinetics of virus elimination from infected tissues in mice and monkeys. In monkeys, MV-N mRNA was detected at day 1 in the buccal cavity with levels declining on day 2, then surging on day 8, suggesting viral replication. There were no unscheduled deaths or treatment related lesions on necropsy. Patients: Three patients were treated with a dose of 106 TCID50 (Table). No DLT was observed. Two patients had MV-N amplified from their gargle specimen. Accrual to dose level 2 has begun. Conclusions: IV administration of MV-NIS is feasible. The virus is capable of traveling to a distant site and replicating before being cleared by the immune system. Patient 2 Patient 2 Patient 3 *copies per microgram RNA of cells derived from gargle sample at each time point: day +3, +8, +15, +22, and +29; no MV-N detected in urine or blood Anti-measles neutralizing Ab titer, pre-Rx / post Rx 1:10 / 1:160 < 1:10 / 1:20 < 1:10 / 1:10 AEs possibly related Gr 2 plts Gr 1 plts, cough, fever, rigors Gr 2 Incr aPTT CD46 copies/cell CD138+ / CD138- BMPC 79,771 / 10,322 140,187 / 10,145 28,258 / 11,228 MV-N QRT-PCR: d3/ d8/ d15/ d22/ d29 (cp/ug RNA)* −/ −/ −/ nd / nd −/ −/ 16,440 / 1405 / − 123-I uptake on SPECT No Uptake day 8 No

Abstract Abstract 2682 Background: The PI3K-Akt pathway is critical to tumor growth in lymphoid malignancies and mTOR inhibitors have shown promising activity in lymphoid malignancies. However, alternate signaling pathways allow cells to escape the effect of mTOR inhibition. Pre-clinical studies have shown that the combination of LBH589, an HDAC inhibitor, with the mTOR inhibitor RAD001 results in potent synergy. We then explored this combination in a phase I/II clinical trial. Patients and Methods: Patients with relapsed multiple myeloma (MM), non-Hodgkin lymphoma (NHL) or Hodgkin Lymphoma (HL) were enrolled into a phase I trial of escalating doses of LBH589 and RAD001. The doses are shown in the table. The study utilized a 3+ 3 design with MTD defined as the maximum dose resulting in less than 2 dose limiting toxicities (DLT) during the first cycle among 6 patients treated at that dose. DLT was defined as a grade 4 neutropenia or thrombocytopenia lasting >= 7 days, febrile neutropenia or any other grade >=3 non-hematologic toxicity considered possibly related to the drugs. Once MTD was determined, patients were enrolled into two separate phase 2 studies, one for relapsed MM and another for relapsed NHL or HL. Results: Twenty-six patients were enrolled to the phase 1 study; 23 were eligible for MTD analysis. There were 16 patients with NHL, 4 with HL and 3 with MM. Median age was 61 (range, 24–73) and 17 were male. The median number of prior therapies was 4 (range 2–11), including a prior stem cell transplant in 11 (48%). No DLT was observed at any of the doses tested in the trial (See below). Hematological toxicities were the most common AEs observed, with a grade 3 or 4 hematologic AE in 15 patients and grade 3 or 4 non-hematologic AEs in 6 patients across all cycles administered. Grade 3 and 4 hematologic AEs included 10 patients with neutropenia and 8 patients with thrombocytopenia. Grade 3 and 4 non-hematologic AEs included hyperglycemia, hypertriglyceridemia, hypophosphatemia, diarrhea, pneumonia and mucositis in one patient each. Overall, 10 responses (43%) were seen (Table). Conclusions: The combination of LBH589 and RAD0001 is tolerated at the doses tested, with hematological toxicities being the most common adverse events. The recommended phase II dose is LBH 40 mg MWF every other week along with 5 mg RAD001 every day in 4-week cycles. Clinical efficacy was seen in all diseases tested with partial responses seen in NHL and HL as well as a minor response in a patient with refractory myeloma, who had previously failed single agent RAD001. Phase 2 trials are ongoing in both disease groups. Disclosures: Kumar: Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Genzyme: Research Funding; Novartis: Research Funding. Off Label Use: Use of the investigational agent MLN9708 for the treatment of previously untreated multiple myeloma. Lacy:Celgene: Research Funding. Reeder:Celgene: Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Novartis: Research Funding.

Abstract Background The presence of circulating plasma cells (PCs) in multiple myeloma (MM) is a known poor prognostic marker. Prior studies have utilized a technically challenging slide-based immunofluorescence technique to detect and quantify the presence of circulating PCs which was not widely adapted in clinical practice. More recently, the routine use of flow cytometry has provided the opportunity to quantitatively assess circulating PCs in MM patients with relative ease. We report the prognostic value of quantifying circulating clonal PCs using multiparametric flow cytometry in MM patients with relapsed disease. Methods We evaluated all MM patients seen at the Mayo Clinic, Rochester from 2009 to 2011 with previous or ongoing relapsed disease and who had their peripheral blood samples evaluated by flow cytometry. Each blood sample had its peripheral blood mononuclear cells isolated by ficoll gradient and stained with antibodies to CD45, CD19, CD38, CD138 and cytoplasmic Kappa and Lambda Ig light chains. A six-color multi-parameter flow cytometer (Becton Dickinson FacsCantos II) was used to examine each sample with a target of detecting 150,000 events (cells) that was then analyzed using the Facs Diva Software. Plasma cells were selectively analyzed through combinatorial gating using light scatter properties and CD38, CD138, CD19, and CD45. Normal PC's were then separated from clonal plasma cells based on the differential expression of CD45, CD19 and polytypic Ig light chains. The clonal plasma cells detected were reported out as the number of clonal events/150,000 collected total events. For those samples where less than 150,000 events were gated or examined, the number of final clonal events was adjusted to 150,000 events. Survival analysis was performed by the Kaplan-Meier method and differences in survival assessed using the log rank test. Results There were 647 consecutive patients with a history of treated MM who had a peripheral blood flow cytometry as part of their routine clinical evaluation. The median patient age was 62 years (29-88) and 55% were male. The median time since diagnosis was 12 months (range: 1-363) and the median number of lines of treatment received was 2 (1-11). There were 81 (13%) patients with clonal circulating PCs with a median of 368 cells (4 – 133,464). The 2-year overall survival (OS) for the 81 (13%) patients with any circulating PCs was 17% compared with 65% for those with none (P<0.001). The presence of circulating clonal PCs was associated with high-risk disease by FISH (P <0.001) as well as higher PCLI (P <0.001). We then correlated the presence of circulating clonal PCs with the disease status at flow cytometry assessment. Among the study patients, only 145 (22%) had actively relapsing disease with the remaining 502 (78%) in a plateau including patients in CR. Circulating clonal PCs were more likely to be detected in patients with actively relapsing disease compared with plateau phase (43% vs. 4%, P < 0.001); none of the CR patients and <5% of the remaining plateau phase patients had any detectable circulating clonal PCs. We then restricted the analysis to the actively relapsing patients; the best cutoff predicting 1-year mortality by ROC analysis was 100 events. Based on this, we defined >=100 events as a cutoff for defining the prognostic role of circulating clonal PCs in actively relapsing patients. The median OS for those with >=100 clonal PC events was 12 months compared with not reached for those with <100 events (p<0.001; Figure 1 ). Among patients with actively relapsing disease, >= 100 circulating PCs was associated with a higher ISS stage, plasma cell labeling index and bone marrow PC% compared with those with <100 circulating PCs. In a multivariable model, only LDH > 222 (HR: 2.08, P = 0.045) and >= 100 circulating PCs (HR: 2.48, P = 0.048) were found to adversely affect OS in actively relapsing patients. Conclusion The utilization of flow cytometry to quantify circulating clonal PCs in patients with relapsed MM appears to have significant prognostic relevance. In patients with actively relapsing disease, >= 100 circulating PCs predicted for worse OS with a median of 12 months. Future studies are needed to determine if this would allow an opportunity to develop a more risk adapted approach for patients with relapsed disease. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract Abstract 863 Background: Patients with MM who have progressed after multiple novel agents have limited treatment options. Pomalidomide (CC4047) is the newest immunomodulatory (IMiD) agent. Pom/dex using a dose of 2 mg/day has demonstrated response rates (≥PR) of 63% in relapsed MM (Lacy, JCO 2009, 27:5008-5014) and 32% in a lenalidomide-refractory cohort (Lacy, Leukemia, in press). The maximum tolerated dose has been determined to be 4 mg/day for 21 of 28 days (Richardson, ASH, 2009), We opened two sequential phase II trials using the Pom/dex regimen at differing doses to study the efficacy of this regimen in patients who have failed both lenalidomide and bortezomib. Methods: Patients refractory to both lenalidomide and bortezomib therapy; defined as relapsing on or within 60 days of stopping each regimen, were enrolled. Pomalidomide was given orally 2 mg daily (Cohort A) or 4mg daily (Cohort B) on days 1–28 of a 28-day cycle with oral dexamethasone given 40 mg daily on days 1, 8, 15 and 22. Response was assessed by the International Myeloma Working Group Uniform Response criteria. All patients received aspirin 325 mg daily for DVT prophylaxis. Results: 35 patients with relapsed and resistant/refractory to both lenalidomide and bortezomib were enrolled in each cohort. The median age was 62 years (range, 39–77) in Cohort A and 61 (range, 45–77) years in Cohort B. The median time from diagnosis to enrollment was 57 months for Cohort A (range 12–249) and 72 months(range, 13–183) for Cohort B. 15 patients had high risk molecular markers in Cohort A and 16 in Cohort B. The median number of prior regimens was 6 in both groups. The median (range) duration on treatment was 5(1-13) and 2(0-6) cycles in cohorts A and B respectively. Toxicity at least possibly attributed to drug consisted primarily of myelosuppression: grade 3/4 neutropenia (37% Cohort A vs. 55% Cohort B); grade 3/4 thrombocytopenia (11% Cohort A vs. 13% Cohort B); and grade 3/4 anemia (9% Cohort A vs. 16% Cohort B). Grade 3/4 non-hematologic toxicities occurred in 23% Cohort A vs. 13% Cohort B. Grade 1 or 2 fatigue was the most common non-hematologic toxicity seen in 43% Cohort A vs. 52% Cohort B. Grade 1 or 2 neuropathy occurred in 17% Cohort A vs. 16% Cohort B. Other non-hematologic toxicities occurring in <5% included pneumonitis, hyperglycemia, renal failure, thrombosis. One patient in cohort B had grade 4 hepatitis. Confirmed responses in Cohort A consisted of VGPR 14%, PR 11%, and MR 24% (ORR 49%, 95% CI: 31–66), and responses in Cohort B consisted of VGPR 9%, PR 20%, and MR 12% (ORR 40%, 95% CI: 23–58). The median follow-up on alive patients was 7.5 months, and 3 months in Cohorts A and B, respectively. The median PFS in cohorts A and B are respectively 6.4 months (95% CI: 4.7-NR) and 3.3 months (95% CI: 2.3-NR). Conclusions: Pom/dex is remarkably active and well tolerated in this heavily pre-treated population of dual bortezomib/lenalidomide-refractory MM patients. The majority of patients have not progressed and objective responses (MR or better) are seen in 40–49%. This study confirms therapeutic benefit for Pom/dex in patients relapsing after other novel therapies. These studies do not show an advantage for the 4 mg/day on days 1–28 of each 28 day cycle did not show an advantage over the 2 mg/day on days 1–28 of each 28 day cycle. Disclosures: Lacy: Celgene: Research Funding. Gertz:Celgene: Honoraria; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dispenzieri:Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Fonseca:Genzyme: Consultancy; Medtronic: Consultancy; BMS: Consultancy; AMGEN: Consultancy; Otsuka: Consultancy; Celegene: Consultancy, Research Funding; Intellikine: Consultancy; Cylene: Research Funding; Onyx: Research Funding; FISH probes prognostication in myeloma: Patents & Royalties. Bergsagel:Celgene: Consultancy; Centocor: Consultancy; Genentech: Consultancy; Amgen: Consultancy; Novartis: Consultancy. Stewart:Celgene: Honoraria.

Abstract Abstract 3963 Background: Pomalidomide at doses of 2 or 4 mg/d has demonstrated excellent activity in patients with relapsed multiple myeloma (MM). Between November 2007 and November 2010, we opened 5 sequential phase 2 trials using the pomalidomide at differing doses with weekly dexamethasone (Pom/dex) regimen to study the efficacy of this regimen. Methods: The five cohorts consisted of: Cohort 1 (N=60): relapsed MM with 1–3 prior regimens, 2 mg dose; Cohort 2 (N=34): lenalidomide refractory, 2 mg dose; Cohort 3 (N=35): bortezomib/lenalidomide refractory, 2 mg dose; Cohort 4 (N=35): bortezomib/lenalidomide refractory, 4 mg dose; and Cohort 5 (N=60) lenalidomide refractory, 1–3 prior regimens, 4 mg dose. Pomalidomide was given orally 2 mg daily or 4mg daily on days 1–28 of a 28-day cycle with oral dexamethasone given 40 mg daily on days 1, 8, 15 and 22. Response was assessed by the International Myeloma Working Group Uniform Response criteria. All patients received aspirin 325 mg daily for DVT prophylaxis or full dose anticoagulation. Results: A total of 225 patients were enrolled across all 5 cohorts. One patient was ineligible and excluded from analysis. The median age was 63 years (32.0–88.0). The median time since diagnosis was 53 months. Forty percent had high-risk molecular markers. Eighty-nine percent had received previous IMIDs including thalidomide (53%) and lenalidomide (81%). Sixty-two percent had previous bortezomib and 73% had prior transplant. The median follow-up is 12.6 months, but varies from 9.4 months for the most recent cohort to 30 months for the first cohort. Sixty-nine percent are alive and 30% remain progression free. Toxicities ≥ grade 3 are shown in table 1 and patient outcomes are shown in Table 2. Conclusions: Pom/dex is remarkably active and well tolerated even in heavily pretreated patients. Responses are durable. Response rates and toxicity are similar between the 2 mg and 4 mg doses. Disclosures: Lacy: Celgene: Research Funding. Fonseca:Consulting:Genzyme, Medtronic, BMS, Amgen, Otsuka, Celgene, Intellikine, Lilly Research Support: Cylene, Onyz, Celgene: Consultancy, Research Funding.