Kumar, Shaji

Abstract Background: Patients (Pts) with multiple myeloma (MM) who relapse within 12 months of autologous stem cell transplantation (SCT) have a poor prognosis. As reported by Mahmood et al. (ASCO 2007), of 432 pts who received SCT at the Mayo Clinic between 1994–2005, those with early relapse within 12 months (94/432– 22%) showed poorer median overall survival. Kaplan-Meier estimates of 12-month survival from the date of first relapse were 37% for pts relapsing within 12 months after SCT as compared to 85% for those relapsing after 12 months. In that study, pts had received regimens other than B. In a recent report of a large, phase III study (DOXIL-MMY3001), the combination of PLD+B improved time to progression (TTP) as compared to B alone (Orlowski et al. JCO 2007). The present analysis examined the 12-month post-randomization survival of patients who had early (<12 months) vs. late (≥12 months) relapse following SCT, as well as the effect of PLD+B vs. B alone in pts who had relapsed early. Methods: This was a retrospective analysis of 646 pts who received intravenous B, 1.3 mg/m2 on days 1,4,8 and 11 of every 21-day cycle ± PLD, 30 mg/m2 on day 4. Results: 359 pts had previously received transplant, 114 (32%) of whom relapsed within 12 months from SCT. The median age, gender distribution, time from diagnosis trial enrollment, measures of disease burden (M-Protein levels and B2M) and renal function were comparable between the early and late relapse groups. There was no difference in overall response rates [complete + partial response (CR+PR)] or very good PR (VGPR) rates between the two groups, or between treatment arms within each group. There was no significant difference in TTP between early vs. late relapse groups (HR=0.94). 12-month survival from randomization was significantly lower in the early relapse group as compared to late relapse (83% vs. 92% respectively, p=0.009). However, within the early relapse group 12-months post-randomization survival rate was significantly superior following treatment with PLD+B as compared to B alone [52/56 patients (93%) vs. 43/58 patients (74%) respectively, p=0.01]. Correspondingly, TTP was better in this group with PLD+B vs. B alone (276 days vs. 205 days respectively, p=0.13). Overall, the toxicity profiles of the combination and B alone were comparable regardless of early or late relapse following SCT. Conclusions: The present analysis of the MMY3001 study corroborates the prior Mayo observation of lower survival in MM pts relapsing within 12 months of SCT. Importantly, it demonstrates that PLD+B may provide a therapeutic advantage for high-risk MM pts with early relapse following SCT.

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 Background: Patients with newly diagnosed multiple myeloma is at increased risk of thrombotic events, primarily venous thrombosis. The risk is significantly increased in patients receiving certain therapeutic regimens such as the combination of thalidomide and dexamethasone. Deep vein thrombosis, especially if complicated by pulmonary embolism, can result in death. It is not clear if venous thrombotic events can result in compromised survival in this group of patients. Methods: We studied patients enrolled in the Eastern Co-operative Group trial (E1A00) that randomized patients with newly diagnosed myeloma to single agent dexamethasone or thalidomide and dexamethasone. Patients with grade 3 or greater thrombotic events (DVT, or myocardial ischemia, or stroke) were identified. Wilcoxon rank sum test (for continuous variables) or Fisher’s exact test (for categorical variables) was used to compare age, baseline M-protein, hemoglobin, WBC, platelets count, creatinine, beta2-microglobulin, or ECOG PS between patients with and without thrombotic events. Results: Among the 207 patients enrolled, 36 patients (17.4%) had grade 3 or greater thrombotic events with any treatment attribution, of whom, 27 patients had DVT, 3 patients had an MI and 6 pts had a stroke. However, in only 31 of these patients were the event considered treatment-related (possible, probable, or definite) and among these 24 had a DVT. The baseline characteristics did not differ between the patients with thrombosis and those without, irrespective of its relationship to treatment. Similarly, the baseline characteristics did not diff for those with venous or arterial thrombosis. The overall survival was similar among the patients developing a DVT compared to those without a thrombotic event, when all DVT events were considered irrespective of the treatment attribution (Figure). However, majority of the patients with an arterial event (3 patients with MI and 6 with stroke) had a short overall survival. Conclusion: Venous thrombosis remains a common complication in patients with myeloma, especially when treated with thalidomide and dexamethasone. While occurrence of thrombosis clearly contributes to morbidity and often leads to dose reductions and missed doses, it does not appear to have an adverse impact on the overall survival of these patients. Figure Figure

Abstract Background: Combination regimens incorporating bortezomib (VELCADE®, Vc), lenalidomide (REVLIMID®, Rev), dexamethasone (Dex) and cyclophosphamide (Cy) (Vc–Dex, Rev–Dex, Vc–Dex–Rev [VDR], and Vc–Dex–Cy [VDC]), have all shown substantial activity in previously untreated multiple myeloma (MM). A combination of all four agents (VDCR) may result in even greater activity. This randomized multi-center 3-arm phase I/II EVOLUTION study is investigating the efficacy and safety of VDR, VDC, and VDCR as initial therapy in previously untreated MM patients (pts). We now report safety and efficacy results from the phase l dose-escalation portion of the study, which sought to determine the maximum tolerated dose (MTD) of the VDCR regimen. These results represent the first clinical data with this novel 4-drug combination that includes bortezomib, lenalidomide, an alkylator, and a corticosteroid. Methods: Pts received Vc 1.3 mg/m2 IV (d 1, 4, 8, 11), Dex 40 mg PO (d 1, 8, 15), Rev 15 mg PO (d 1–14), plus Cy 100, 200, 300, 400, or 500 mg/m2 PO (d 1, 8) for up to eight 21-d cycles, followed by Vc 1.3 mg/m2 (d 1, 8, 15, 22) for four 42-d maintenance cycles. Pts received prophylactic antibiotics, acyclovir, transfusion support and concomitant anticoagulants as required. Eligible pts wishing to receive autologous stem cell transplant (ASCT) could undergo stem cell mobilization any time after cycle 2, and discontinue therapy for ASCT any time after cycle 4. The MTD was defined as the highest dose of Cy in combination with VDR resulting in ≤1 dose-limiting toxicity (DLT) in 6 pts. A DLT was defined as: platelet count <25,000/mm3 lasting >7 days or any platelet count <10,000/mm3; grade 4 neutropenia lasting >7 days; any ≥grade 3 non-hematologic toxicity considered to be related to Cy except for inadequately treated nausea, vomiting, and diarrhea, or any toxicity resulting in a >2 week treatment delay. Results: Twenty-six pts were enrolled; 1 pt was not dosed due to a heart problem and was excluded (dose level 4) and 4 pts were not evaluable for DLT. In the 25 treated pts, median age was 61 years (range 49–79); 52% were male; 48% had ISS Stage lI and 4% Stage III disease, and 44% had KPS ≤80%. At data cut-off, 11 pts remain on treatment and 9 have undergone successful ASCT. To date, median treatment duration is 4 cycles (range 2–11). Two pts experienced DLT: 1 grade 4 febrile neutropenia at dose level 4 (Cy 400 mg/m2), and 1 grade 3 herpes zoster virus reactivation despite antiviral prophylaxis at dose level 5 (Cy 500 mg/m2). The recommended phase II dose of Cy in the VDCR regimen was the highest planned dose of 500 mg/m2. The most common treatment-emergent AEs were constipation (64%), fatigue (60%), and nausea (52%). Hematologic toxicities were acceptable, with grade 3 neutropenia in 16% of patients, grade 4 in 4%, and grade 4 thrombocytopenia in 4%. Peripheral neuropathy (56%), included 8% grade 3 but no grade 4; no deep-vein thrombosis/pulmonary embolism events were reported. Overall rate of serious AEs was 40%; the only SAE reported in >1 pt was febrile neutropenia (2 pts). Best responses to date by International Uniform Response Criteria are shown in the table. Preliminary response rates are: 100% ≥PR, 68% ≥VGPR, 32% CR/nCR, 28% CR/stringent CR and 20% sCR. Ten pts have undergone stem cell mobilization with median CD34+ yield of 4.95×106/kg. Conclusions: VDCR was well tolerated and hematologic toxicities were manageable. The current study shows that the VDCR regimen is feasible and highly active in newly diagnosed myeloma and merits further testing in clinical trials. Enrollment to the 3 arms (VDR, VDC and VDCR) of the phase ll portion of the study and testing for minimal residual disease by flow cytometry are ongoing. Best unconfirmed response to date with VDCR Dose level 1 2 3 4 5 Cyclophosphamide dose, mg/m2 100 200 300 400 500 Enrolled 3 4 4 8 7 Treated 3 4 4 7 7 Still on treatment – 1 1 2 7 Best unconfirmed response to date CR (sCR) 2 (2) 1 (1) 1 (1) 2 1 (1) VGPR (nCR) 1 – 3 (1) 4 2 PR – 3 – 1 4

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 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.