Abstract Background: High dose therapy (HDT) and stem cell transplant has been shown to improve survival in patients with myeloma and remains the standard of care. However, the reported results of initial HDT in these patients reflect the combined effect of the initial therapy and the HDT. The contribution of HDT on its own is often difficult to analyze in this group of patients with varying degree of response to initial therapy. In this single institution retrospective study, we have analyzed the results of HDT in a group of patients with measurable disease at the time of HDT. Methods: We identified patients from our transplant database, who had measurable disease at the time of initiation of transplant as defined by a serum M protein of ≥ 1.0 g/dL, 24 hour urine M-protein ≥ 200 mg or a bone marrow plasma cell % of ≥ 30. Details regarding the clinical outcome were obtained from the database and from patient clinical records. Chi square test was used for comparison of nominal variables and t-test for continuous variables. Kaplan Meier analysis was used for comparing survival and Cox proportional hazards was employed to identify predictors of progression free and overall survival. Responses were defined by the EBMTR criteria, using the measurements at the time HDT and the lowest measurement obtained. VGPR required a 90% reduction in the serum M component with urine protein < 100 mg/24 hours. Results: A total of 440 patients were studied; 271 (61.5%) of whom had a transplant within one year of their diagnosis. Among the 271 patients, 140 (52%) were in the initial plateau, 99 (36%) failed to achieve a PR to initial therapy and 32 (12%) were in their first relapse. Given the known differences in the outcome between these groups of patients, those receiving an early transplant were analyzed separately. The response rates included CR (24%), VGPR (7%), PR (52%), MR or less (17%) and among the late transplants CR (23%), VGPR (8%), PR (61%) and MR or less (8%). The median progression free survival was 23.6 mos and the overall survival from HDT was 62 mos. In a multivariate analysis, presence of cytogenetic abnormalities (RR: 2.5) and high plasma cell labeling index (≥ 1%) (RR: 2.4) at HDT and failure to achieve a CR or VGPR (RR: 1.7) were prognostic for decreased progression free survival post HDT. In a similar model, only high PCLI (RR: 2.8) and abnormal cytogenetics (RR: 2.5) at HDT predicted for poor overall survival after transplant. Conclusion: This study provides a sense of the contribution of HDT, independent of the initial therapy, by determining responses based on the immediate pre-transplant disease measurements and the best values observed post transplant. In this group of patients with residual measurable disease after the initial therapy, HDT therapy leads to complete responses in nearly a quarter of the patients and a VGPR in another 7%, an outcome associated with better progressin free survival. While measurements at transplant do not correlate strictly with response to initial therapy, the aim of this study was to understand the individual contribution of HDT in these patients. Thus some of the patients who would have been classified as having a partial response to induction and HDT may be classified as non-responders in this analysis. These numbers will provide a historical comparison for trials evaluating novel consolidation therapies for myeloma.
Analysis of Outcome after Autologous Stem Transplantation in Patients with Newly Diagnosed Myeloma: Comparison of Different Induction Regimens.
Abstract Background: Autologous stem cell transplantation (SCT) improves survival in patients (pts) with multiple myeloma (MM). We have previously demonstrated that the degree of response at transplant does not impact on the outcome of transplant. However, newer induction regimens such as thalidomide and dexamethasone (Thal-Dex) result in higher response rates compared to previously used regimens such as single agent dexamethasone or vincristine, doxorubicin, and dexamethasone (VAD). We examined the outcome of SCT following three different induction therapies for newly diagnosed MM, namely VAD, single agent Dex, and Thal-Dex. Patients and Methods: 340 patients with MM who received their SCT within 12 mos of diagnosis (median 5.8, range 3–12) were studied. Patients receiving more than one induction therapy as well as those in whom thalidomide was added to dexamethasone for lack of response were excluded from the analysis. There were 105 pts in the VAD group, 140 in the Dex group and 95 in the Thal-Dex group. Responses were defined using standard criteria. Results: The study cohort consisted of 209 males (59%), with a median age of 57 years (range 30–76) at transplant. Baseline characteristics were similar in the 3 groups, except for lower age in the VAD group (median 55.8) compared to Dex (59.6) and Thal Dex (57.4) and shorter time to transplant in the Dex group (5.4 m) compared to VAD (6.4) and Thal Dex (5.9). Markers of disease activity pre-transplant, including B2M and marrow plasma cell percentage were higher in the Dex group compared to either VAD or Thal Dex. The proportion of patients with any response to induction therapy was lower in the Dex group compared to the other two. All pts in the Dex and the Thal-Dex groups received melphalan only conditioning compared to 70% in the VAD group, the rest receiving Melphalan/TBI. An objective response was achieved after SCT in 96%, 97%, and 98% of pts in the VAD, Dex and Thal-Dex groups respectively (P=0.8). A complete response to SCT was seen in 49% of patients in VAD group, 45% among those in the Dex group and 38% among those in the Thal Dex group (P=0.38). There was no difference in the median progression free survival after transplant (P=0.21) or overall survival from diagnosis (P=.34) between the three groups. The proportion free from progression at 2 years post transplant was 54%, 55% and 46% for Dex, VAD and Thal-Dex respectively. The proportion surviving at 4 years from diagnosis was 64%, 65.4% and 72% respectively for the three groups. Conclusion: We did not observe any difference in the response rates including complete responses to SCT in the three groups with nearly all pts in each group achieving a response. The progression free survival and overall survival appear to be comparable between the three groups. The results from initial therapy cannot be compared between the three regimens since the study population is restricted to patients reaching stem cell transplant. Within the limits of the study, there does not appear to be any long term impact of the initial therapy for the patients going onto an early stem cell transplant. Figure Figure
Deep Vein Thrombosis in Myeloma: Estimate of Prevelance and Recommendations for Therapy Based upon a Survey of Members of the International Myeloma Working Group (IMWG).
Abstract Purpose: Deep vein thrombosis (DVT) is increasingly recognized as a major complication of thalidomide (T; Thal) and lenalidomide (R; Rev) based therapy for multiple myeloma. Estimated incidence varies widely in the literature. There is no consensus on specific risk factors, indications for thromboprophylaxis or the agent of choice for DVT prophylaxis. The purpose of this study was to develop a consensus among members of the IMWG. Patients and Methods: A survey was electronically mailed to 67 IMWG members on July 21, 2006 and consisted of 24 multiple-choice questions. Results: Twenty-three IMWG members (34%) sent in their responses by the cut-off date. All (100%) felt that DVT was an important question, but most (95%) did not avoid Thal/Rev based therapy because of the DVT risk. Overall results are summarized in the Table below. A majority of physicians felt that concomitant therapy with high dose dexamethasone (90% of physicians), alkylators (55%), doxorubicin/liposomal doxorubicin (90%), and erythropoietin (75%) increase the risk of DVT associated with Thal or Rev based therapy. Aspirin (81 mg or 325 mg per day) was the preferred choice of prophylaxis when necessary. However, 65% of respondents preferred warfarin to a therapeutic INR or LMW heparin if either doxorubicin or liposomal doxorubicin was added to the regimens. Most (95–100%) felt that DVT prophylaxis was not indicated for: VAD, MP, bortezomib +/− dexamethasone regimens. Seventy-five percent felt it to be safe to resume therapy with Thal/Rev after therapeutic anticoagulation. Most (95%) believed randomized trials were needed. Conclusion: DVT is recognized as a major clinical problem associated with Thal/Rev containing regimens. Most respondents felt that the DVT risk did not warrant any prophylaxis when either Thal or Rev were used as single agents. Aspirin was the preferred form of DVT prophylaxis for most Thal/Rev containing regimens, except when doxorubicin/liposomal doxorubicin or melphalan were added. Additional responses will be analyzed both electronically and by conference call prior to the meeting. Therapy Estimated incidence of DVT (% respondents) Choice of thromboprophylaxis (% respondents) Single agent thal <5% (61%) None (65%) Single agent Rev <5% (80%) None (65%) Thal-Dex 10–20% (52%) Aspirin (60%) Rev-Dex 10–20% (48%) Aspirin (60%) MPT 10–20% (65%) Aspirin (40%) R-MP 5–10% (57%) Aspirin (70%)
Genomic abnormalities in monoclonal gammopathy of undetermined significance
Translocations involving immunoglobulin (Ig) loci and chromosome 13 monosomy (Δ13) are frequent cytogenetic findings in multiple myeloma (MM). Similar chromosomal aberrations have been identified in the monoclonal gammopathy of undetermined significance (MGUS), but their prevalence and significance remain uncertain. Bone marrow from 72 patients with MGUS (n = 62) and smoldering MM (n = 10) was evaluated for translocations between the Ig heavy chain (IgH) and chromosomes 4, 11, and 16, translocations involving Ig light chain–lambda (IgL-λ, and Δ13. Fluorescence in situ hybridization (FISH) analysis was done on clonal plasma cells (PCs) detected by immunofluorescence (cIg-FISH) of the cytoplasmic light chain. We also studied cells for cyclin D1 and FGFR3 up-regulation by immunohistochemistry and immunofluorescence, respectively. Twenty-seven (46%) of 59 patients had IgH translocations, and 4 (11%) of 37 had an IgL-λ translocation. A t(11;14)(q13;q32) was found in 15 (25%) of 59 patients, a t(4;14)(p16.3;q32) in 9% of patients, and a t(14;16)(q32;q23) in 5% of patients. All patients with t(4;14)(p16.3;q32) tested (n = 3) had intense cytoplasmic fluorescence with an anti-FGFR3 antibody. PC nuclear staining of cyclin D1 was only observed in patients with t(11;14)(q13;q32); Δ13 was detected in the clonal PCs in 50% of patients. The percentage of abnormal PCs varied with any given abnormality. No obvious clinical or biologic correlations were associated with these chromosome abnormalities. Similar translocations are found in both MGUS and MM, including t(4;14)(p16.3;q32) and t(14;16)(q32;q23). Moreover, Δ13 is common in MGUS and unlikely to play a predominant role in the evolution of MGUS to MM.
Natural History, Genetic Aberrations and Survival Distinguish Primary Plasma Cell Leukemia from Multiple Myeloma with Leukemic Transformation.
Abstract Plasma cell leukemia (PCL) is an aggressive and rare hematological malignancy that can originate either as primary disease (pPCL) or as a leukemic transformation of multiple myeloma (MMLT). We report here on the clinical characteristics, survival and genetic studies of 80 patients with PCL treated at a single institution (including 41 with pPCL and 39 with MMLT) and make comparisons with 439 newly diagnosed cases of multiple myeloma (MM). From our results pPCL presents a decade earlier than MMLT (54.7 vs 65.3 years) and despite substantially poorer clinical and laboratory parameters at presentation (hepatomegaly 32% vs 11%, leukocytes 31.6 vs 20.9, β2M 8.5 vs 4.3) pPCL appears more responsive to conventional combination chemotherapy (VAD, VBMVP or VBAP) than MMLT and is associated with significantly longer survival (median 18.4 vs 3 months). Comparison of pPCL groups treated with combination chemotherapy (n=21) or with other regimens (40% MP, 10% Thal/Dex, 20% other, 30% none)(n=20) identifies no substantial pre-treatment differences between the groups although a higher proportion of patients who received combination chemotherapy subsequently proceeded to stem cell transplantation (30 vs 10%). Importantly, survival of pPCL patients treated initially with combination chemotherapy (median 13.9, mean 27.3 months) was significantly longer compared with patients who did not receive combination chemotherapy (median 5.2, mean 9.9 months)(p=0.035) with 2 long term survivors (> 7 years) in the chemotherapy group. By comparison, patients with MMLT received less active therapy for their leukemic disease than did patients with pPCL (21% VAD, VBMVP or VBAP; 18% MP). Treated MMLT patients showed selection bias for younger age (60.9 vs 66.4 years) and lack of bone disease (0 vs 65%)(p<0.01); however despite this, median survival was disappointingly short for MMLT patients in the treatment group and was not significantly improved compared with non-treated patients (2.3 vs 0.8 months)(p=0.34). Assessment of novel therapies in PCL is therefore urgently required. Karyotype analysis and targeted genetic studies demonstrate that IgH translocations are present with high frequency in both pPCL and MMLT (71 vs 86%) compared with MM (~50%). Notably, IgH translocation in pPCL is almost exclusively targeted at chromosome 11 (cyclin D1) belying its importance in establishing the phenotype. IgH translocation in MMLT is primarily to chromosome 11 [71%], but also targets chromosomes 4 (FGFR3/MMSET) [13%] and 16 (cMaf) [20%], recapitulating MM. Abnormalities of chromosomes 3,5,7,9,11,13,15 and 19 are present equally in all 3 disorders. Deletion of 17p13 (p53) shows strong selection pressure in the leukemias (pPCL 53.8%, MMLT 48.8%, MM 10.7%) and is complemented by p53 mutation (23%). Notably, pPCL tumors show lower rates of Ras mutation (12 vs 40%) and p14 (0 vs 31%) or p16 (25 vs 40%) promoter methylation than MMLT. Together these results therefore indicate that pPCL and MMLT are fundamentally different plasma cell disorders with distinctive biology, genetic abnormalities and treatment responses.
Transplantation without Growth Factor. Engraftment Kinetics Following Stem Cell Transplantation for Primary Systemic Amyloidosis.
INTRODUCTION The use of growth factors filgrastim and sargramostim are associated with often dramatic degrees of fluid retention in patients with amyloidosis who have coexistent cardiac involvement or nephrotic syndrome. Significant degrees of fluid retention can complicate the post transplant management of patients with AL receiving high dose chemotherapy. We report outcomes in a cohort of amyloidosis patients who received no growth factor support post transplant. PATIENTS AND METHODS 283 consecutive patients seen for stem cell transplant are included in this cohort. In order to be considered evaluable for engraftment the patient must have survived for 30 days or was excluded from analysis. All patients had biopsy verified AL. Patients also had to have visceral organ dysfunction in order to be eligible for stem cell transplant with a minimum of one visceral organ involved. RESULTS Among 283 patients transplanted, 244 were evaluable for engraftment. There were 145 men (59%). Renal involvement was present in 163 (67%), cardiac involvement by echocardiography in 47%, hepatic involvement in 16%, and peripheral nerve involvement in 11%. The median age was 56.6 years (range 33–73). The median time from diagnosis of amyloidosis to stem cell transplantation was 4.2 months. A neutrophil count of 500/uL was achieved in 50%, 75%, and 90% of the total group at 14, 16, and 22 days respectively (figure 1). A platelet count of 20,000/uL was achieved in 50%, 75%, and 90% of patients at 14, 19, and 28 days respectively (figure 2). A platelet count of 50,000/uL was achieved in 50%, 75%, and 90% of patients at 18, 28, and 52 days respectively. The median time spent in the hospital for the entire cohort 9 days. 46 of the patients (19%) completed the entire procedure as an outpatient. 75% of patients were discharged within 18 days and 90% were discharged within 32 days. 137 patients were blood culture negative throughout the entire procedure (56%). A blood culture was positive in the remaining 107 patients. 68 of these 107 contained a culture for Staph. coagulase negative. 39 (16%) had bacteremia associated with other organisms. CONCLUSION Transplantation of patients with amyloidosis without using growth factor is feasible. The median time to achieve neutrophil and platelet counts of 500 and 20,000/uL respectively is 14 days. It is reasonable to withhold growth factor from AL patients undergoing stem cell transplantation. Figure Figure Figure Figure
Long-Term Survival (10 Years or More) in 30 Patients With Primary Amyloidosis
The median survival in primary systemic (AL) amyloidosis is less than 18 months. No published series of patients with AL amyloidosis have reported survival of more than 10 years. The records of all Mayo Clinic patients with a diagnosis of AL amyloidosis between January 1, 1966 and March 1, 1987 were reviewed. Patients with secondary amyloidosis, familial amyloidosis, senile systemic amyloidosis, and localized amyloidosis were excluded. During the 21 years of the study, 841 patients with AL amyloidosis were seen. Of these, 29 were excluded because the diagnosis was made at autopsy, and 2 others were excluded because no follow-up data were available. Actuarial survival for the 810 patients was 51% at 1 year, 16% at 5 years, and 4.7% at 10 years. Thirty patients survived for 10 years or more after the histologic diagnosis of AL amyloidosis; all received alkylating-agent therapy. In 14 patients, the monoclonal protein disappeared from the serum or urine. Of 10 patients with nephrotic syndrome, 4 had an objective response. Congestive heart failure, older age, creatinine value of 2 mg/dL or more, bone marrow plasma cell value of 20% or more, platelet count of 500 × 109/L or less, and the presence of peripheral neuropathy were underrepresented in the 10-year survivors and are unfavorable prognostic features. Five percent of patients with AL amyloidosis survived for 10 years or more.
Autologous Stem Cell Transplantation for Multiple Myeloma in Patients with Reduced Renal Function: A Matched Set Comparison.
Abstract Background: Renal insufficiency of varying severity including end stage renal disease requiring dialysis is often a presenting manifestation of multiple myeloma (MM). While many patients (pts) improve following initiation of therapy for MM, a considerable number of pts proceed to stem cell transplant with less than optimal renal function. It is not clear whether the outcome of their transplants differs from pts with normal renal function. Methods: The MM transplant database was searched to identify pts with a Creatinine clearance (Crcl) of less than 50 ml/min/m2 (study cohort). These pts were then matched to two pts each with a clearance of ≥ 50 ml/min/m2 (control cohort), based on cytogenetic abnormalities (normal vs. abnormal), circulating plasma cells (yes vs. no), age at transplant, % of plasma cells at transplant, plasma cell labeling index, time to transplant from diagnosis and the disease status at transplant, the factors used in that order of importance. Results: Eighty pts with a Crcl < 50 ml/min were identified and matched to 160 pts with Crcl ≥ 50 ml/min. The pts were matched for the above factors and the two groups were similar in terms of their other baseline features except CRP and B2M, both of which were lower in the control group. Pts with reduced renal function were more likely to receive dose reduced melphalan for conditioning (32.5%) compared to the control group (2%; P < 0.0001). The outcomes from the stem cell transplant were similar in both the groups. 96% of pts obtained an objective response to stem cell transplant in each of the groups with no difference in the time to response; and a complete response was seen in 38.5% and 36.6% of the study and control cohorts respectively (P=NS). The median post transplant progression free survival was 18.2 months and 18.4 mos respectively for the study cohort and the control group (P=0.4). However, the median overall survival from transplant was shorter for the study cohort (30.7 mos vs. 60 mos for the controls; P = 0.007; Figure). The time to platelet and neutrophil engraftment was not different between the groups. In terms of transplant related toxicity, the median days hospitalized was higher in the study group (5 days vs. 9.5 days; P=0.003) as was the incidence of grade 3 and 4 mucositis (8% vs. 23%; P= 0.0008). Six pts (7.5%) had treatment related deaths in the study group compared to 3 pts (2%) among the controls (P=0.03), the majority of the deaths being infection related. Conclusion: Here we demonstrate that pts with MM and reduced renal function derive disease free survival comparable to those with normal renal function, despite the increased use of reduced dose Melphalan for conditioning. The toxicity is clearly increased in the presence of abnormal renal function. Interestingly, the overall survival was inferior among the pts with reduced renal function. One possible explanation for this observation is the decreased availability of novel therapies for salvage among pts with reduced renal function as many of them would not be eligible for clinical trials due to reduced renal function. Figure Figure
Long-Term Results of Single-Agent Thalidomide as Initial Therapy for Asymptomatic (Smoldering or Indolent) Myeloma.
Abstract Background: Patients with early stage myeloma are typically observed without therapy until symptomatic disease occurs. We have reported early results of therapy with single-agent thalidomide as initial therapy for early stage multiple myeloma in an attempt to delay progression to symptomatic disease (Leukemia2003;17:775–9). We now report the long-term results of this phase II trial. Methods: Thirty-one patients with smoldering or indolent multiple myeloma were enrolled between April 1999–March 2002. All pts had bone marrow (BM) plasma cells >=10% and measurable disease defined as serum monoclonal (M) protein >=2gm/dL and/or urine M protein >=400mg/24 hours. Two patients were deemed ineligible because they were found to have received prior therapy for myeloma and were excluded from analysis. Thalidomide was initiated at a dose of 200 mg/day and increased as tolerated by 200 mg/day every 2 weeks to a maximum dose of 800 mg/day. The dose of thalidomide was decreased as needed to minimize toxicity. Treatment was continued until disease progression or serious toxicity, except for patients achieving less than a minor response (<25% paraprotein reduction) to therapy in whom therapy was stopped at one year. Response was defined as a decrease in serum and urine monoclonal (M) protein by 50% or higher. If the serum M protein was unmeasurable, a 90% or higher decrease in urine M protein was required. Responses need to be confirmed at least 4 weeks apart. Results: Ten patients (34%) had indolent myeloma, including 4 patients with lytic bone lesions, 3 patients with anemia (Hb <11gm/dL), and 3 patients with both anemia and lytic bone lesions. Median follow up of living patients is 5.6 years (range, 4.0–7.1 years). Of the twenty-nine eligible patients, ten (34%) had a partial response to therapy with at least 50% or greater reduction in serum and urine monoclonal (M) protein. Three patients are still on study and receiving therapy. The remaining have gone off-study: seven patients (27%)had progressive disease while on therapy; other reasons for ending study treatment included completed therapy per protocol (2 pts), patient refusal (2pts), toxicity (8 pts), alternate treatment (3 pts), other medical problems (1 pt), died on study (1 pt), and other (2 pts). The median time to progression (TTP) was 3.2 years (95% CI 2.1–5.6 yrs). Median progression free survival (PFS) was 3.0 yrs (95% CI 2.0–5.1 yrs). Median overall survival has not been reached; 5 year survival rate by the Kaplan Meier method is 60%. Major grade 3–4 non-hematologic adverse events at any time during therapy were noted in 34% of patients; this includes 14% with grade 4 toxicity. Grade 3–4 toxicities occurring in more than one patient include neuropathy (2 pts) and sinus bradycardia (2 pts). Conclusions: Thalidomide has activity in asymptomatic myeloma. This approach must be further tested in randomized trials to determine if the survival estimates are superior to observation. Given the activity of thalidomide, trials are also needed with lenalidomide.
Phase I/II, Multicenter, Open-Label, Dose-Escalation Study of Bendamustine in Combination with Lenalidomide and Dexamethasone (BRD) in Patients with Relapsed Multiple Myeloma: A Multiple Myeloma Research Consortium Study.
Abstract Abstract 2965 Background: Alkylating agents have been the mainstay of multiple myeloma (MM) therapy for decades and despite introduction of several new therapies, it continues to play a significant role in its management as part of various drug combinations. While melphalan has been the most commonly used alkylator in MM, recent studies have suggested significant activity for bendamustine, a bifunctional alkylator. The combination of lenalidomide and melphalan has been associated with high response rates in relapse and newly diagnosed MM. Based on these promising results we designed a trial to evaluate the maximally tolerated dose of lenalidomide and bendamustine when used in combination as well as the efficacy of the combination in relapsed disease. Patients and Methods: Patients with relapsed MM and measurable disease were enrolled on this phase 1/2 trial provided they had not more than 4 prior lines of therapy for MM, had adequate performance status and organ and hematological function. Patients refractory to lenalidomide were allowed to enroll. The primary objectives were to (i) to determine the MTD of bendamustine and lenalidomide in combination with dexamethasone in subjects with relapsed MM (phase 1) and (ii) to evaluate the confirmed response rate of bendamustine in combination with lenalidomide and dexamethasone in patients with relapsed MM (phase 2). Bendamustine (B) was administered on days 1 and 2 of a 28-day cycle at doses of 50–100 mg/m2. Lenalidomide (R) was given days 1–21 at doses of 15–25 mg daily. Dexamethasone (D) was administered at 40 mg weekly. Dose escalation was done using a 3+3 design and MTD was defined as one dose level below that resulted in >=2 DLTS among 6 patients. The primary end point for this trial was the proportion of patients with confirmed hematologic response (sCR, CR, VGPR, or PR) over the first 6 cycles of treatment. Results: A total of 72 patients were accrued to this study from March 2010 to May 2012: 21 patients in phase 1 and 51 in phase 2. The 6 patients from the MTD dose level of phase 1 were also included in phase 2. The median age of all 72 patients was 62.1 (range, 40–86) and 57% were male. Majority (75%) of patients had previously been exposed to lenalidomide and 69% had prior exposure to bortezomib. Median # of prior therapies was 3 (range, 1–5) and 74% of patients had a prior autologous stem cell transplant. Patients have received a median of 4 cycles (range, 1–25), with 27 patients still continuing on active treatment. Disease progression led to study discontinuation in 22 (49%) and adverse events were the reason for discontinuation in 14 (31%). In phase I, two DLTs (Grade (Gr) 2 neuropathy and Gr 4 neutropenia) were seen at the highest dose level (100 mg/m2 B, 25 mg R), and the MTD was determined as 75 mg/m2 of B given days 1 and 2 and 25 mg of R days 1–21, along with D 40 mg weekly. Overall patients, 12/21 (57%) had a PR or better. In phase 2, 17 (40%) confirmed responses (>=PR) were seen among the 43 patients evaluable for response (received at least 6 cycles of treatment or have gone off study prior to 6 cycles); including 9 (21%) VGPR and 8 (19%) PR. An additional 5 patients had a minor response. Over all dose levels, a gr 3 or higher adverse event at least possibly attributed to the study was seen in 75% of patients. The most common toxicities were all hematological (thrombocytopenia and leukopenia), and most common non-hematological toxicity was infection. Prolonged time to recovery of blood counts was seen in a few patients, but majority of patients were able to tolerate the regimen with adequate dose reductions. Conclusion: The recommended dose of the combination for further studies is bendamustine at 75 mg/m2 days 1 and 2, lenalidomide 25 mg daily on days 1–21 and dexamethasone days 1, 8, 15, 22; with cycles repeated every 28 days. The regimen is well tolerated with hematological toxicity being the most common and manageable with dose reductions. The regimen is effective with high response rates and durable responses seen. Updated results with response rates and time to event analyses will be available for the entire cohort at the time of meeting. Disclosures: Kumar: Merck: Consultancy, Honoraria; Celgene: Research Funding; Millennium: Research Funding; Novartis: Research Funding; Cephalon: Research Funding; Genzyme: Research Funding. Krishnan:celgene: Consultancy, Speakers Bureau. Zimmerman:Celgene: Honoraria; Millennium: Honoraria; Novartis: Expert Testimony, Expert Testimony Other. Vij:Teva: Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Millennium: Speakers Bureau; Onyx: Honoraria, Research Funding.