17569 Background: Lenalidomide is an immunomodulatory drug of the IMiD class that has activity in multiple myeloma, myelodysplastic syndromes and chronic lymphocytic leukemia. We report preliminary results of two Phase II studies assessing the safety and efficacy of lenalidomide monotherapy in subjects with relapsed/refractory indolent or aggressive non-Hodgkin’s lymphoma (NHL). Methods: Subjects with indolent (study NHL-001) or aggressive (study NHL-002) relapsed/refractory NHL following ≥ 1 prior treatment regimen with measurable disease are eligible. Subjects receive 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continue therapy for 52 weeks as tolerated until disease progression. Response and progression are evaluated using cross sectional imaging by the NCI criteria. Results: 10 subjects (2 indolent (I), 8 aggressive (A)) of a planned 80 (40 in each study) have enrolled thus far. Median age is 66 (45–80) and 7 subjects are female. Indolent histology is follicular center lymphoma grade 1, 2 (n = 2) and aggressive histology diffuse large cell lymphoma (n = 7) and follicular center lymphoma grade 3 (n = 1). Median time from diagnosis to lenalidomide monotherapy is 2.9 years (1.1–10) and median number of prior treatment regimens per subject is 3 (1–6). Median duration of follow-up is 2 months. Of eight subjects (2 I, 6 A) evaluable for response at two months, three demonstrated a decrease in their tumor burden by 72% (I), 68% (A) and 52% (A), two subjects (2 A) exhibited stable disease and three subjects (1 I, 2 A) had disease progression. Six of the ten subjects (2 I, 4 A) demonstrated no Grade 3 or 4 adverse events. Grade 3 or 4 hematological adverse events (neutropenia, thrombocytopenia) occurred in four subjects including one febrile neutropenia and one of these four subjects also exhibited Grade 3 cellulitis. No tumor flare or tumor lysis has been observed to date. Conclusions: Preliminary data of lenalidomide monotherapy in relapsed and refractory NHL are encouraging. [Table: see text]
Preliminary results from a phase II study of lenalidomide oral monotherapy in relapsed/refractory indolent non-Hodgkin lymphoma
8066 Background: Lenalidomide, an immunomodulatory drug, is approved in the US for treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes associated with a deletion 5q[31] cytogenetic abnormality. Lenalidomide also has activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma. This study was designed to assess the safety and efficacy of lenalidomide monotherapy in patients with relapsed/refractory indolent non-Hodgkin's lymphoma (NHL). Methods: Patients with relapsed/refractory indolent NHL with measurable disease after at least 1 prior treatment regimen were eligible. Patients received 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continued therapy for 52 weeks as tolerated or until disease progression. Response and progression were evaluated using the IWLRC methodology. Results: As of enrollment cut-off, 43 patients received drug and 27 were evaluable for response. The median age was 63 (43–82) and 12 were female. Histology was small lymphocytic lymphoma [SLL] (n=12), follicular center lymphoma grades 1,2 [FCL] (n=12) and nodal marginal B-cell lymphoma [NML] (n=3). Median time from diagnosis to lenalidomide was 4.3 (0.4- 24) years and median number of prior treatment regimens was 3 (1–17). Seven patients (26%) exhibited an objective response (2 complete responses (CR), 1 complete response unconfirmed (CRu) and 4 partial responses (PR)), 9 had stable disease (SD) for a tumor control rate (TCR) of 59% and 11 progressive disease (PD). Responses were produced in each of the indolent histologic subtypes studied: SLL (3/12), FCL (3/12) and NML (1/3). Since most responses develop at ≥ 4 months, additional responses may be seen in early SD patients with longer follow-up. Five patients (12%) exhibited Grade 4 neutropenia, and Grade 3 adverse events were neutropenia (16%) and thrombocytopenia (14%). Conclusion: Lenalidomide oral monotherapy is active with manageable side effects in relapsed/refractory indolent NHL. [Table: see text]
Preliminary results from a phase II study of lenalidomide oral monotherapy in relapsed/refractory aggressive non-Hodgkin lymphoma
8052 Background: Lenalidomide (Revlimid), an immunomodulatory drug of the IMiDs class, is approved in the US for treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes associated with a deletion 5q[31] cytogenetic abnormality. Lenalidomide also has activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma. This study was designed to assess the safety and efficacy of lenalidomide in patients with relapsed/refractory aggressive non-Hodgkin's lymphoma (NHL). Methods: Patients with relapsed/refractory aggressive NHL with measurable disease after at least 1 prior treatment regimen were eligible. Patients received 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continued therapy for 52 weeks as tolerated or until disease progression. Response and progression were evaluated using the IWLRC methodology. Results: As of enrollment cut-off, 50 patients were enrolled and 49 received drug. Forty-one patients were evaluable for response. The median age was 65 (46–84) and 18 were female. Histology was diffuse large B-cell lymphoma [DLBCL] (n=21), follicular center lymphoma grade 3 [FL] (n=3), mantle cell lymphoma [MCL] (n=14) and transformed [TSF] (n=3). Median time from diagnosis to lenalidomide was 3.2 (0.4–32) years and median number of prior treatment regimens was 3 (1–7). Fourteen patients (34%) exhibited an objective response (5 complete responses unconfirmed (CRu) and 9 partial responses (PR)), 12 had stable disease (SD) for a tumor control rate (TCR) of 63% and 15 progressive disease (PD). Responses were seen in each of the aggressive histologic subtypes studied: DLBCL (5/21), MCL (6/14), FL (2/3), and TSF (1/3). Five of 11 patients (45%) with a prior stem cell transplant responded. Progression free survival although ongoing is currently > 239 (>191 - >373) days in patients experiencing CRu and > 160 (>54 - >251) days in patients with PR. Most common Grade 4 adverse events were neutropenia (8.2%) and thrombocytopenia (8.2%) while most common Grade 3 adverse events were neutropenia (22%), leukopenia (14%) and thrombocytopenia (12%). Conclusion: Lenalidomide oral monotherapy is active with manageable side effects in relapsed/refractory aggressive NHL. No significant financial relationships to disclose.
Longer Duration of Treatment and Maintenance of Best Response with Lenalidomide and Dexamethasone Prolongs Overall Survival in Patients with Relapsed or Refractory Multiple Myeloma
Abstract Introduction: Multiple myeloma (MM) accounts for about 20% of deaths from hematological cancers and remains incurable despite conventional and high-dose chemotherapy. Two phase III trials in patients with relapsed or refractory MM (MM-009 and MM-010) showed that lenalidomide combined with dexamethasone resulted in significantly improved response rates and significantly prolonged median time to progression (TTP) and overall survival (OS) compared with dexamethasone alone. This current sub-analysis of lenalidomide plus dexamethasone therapy assessed whether there was a survival benefit in maintaining patients on therapy after achieving their best response and what the impact of early discontinuation on TTP and OS was. Methods: Of the 353 patients from MM-009 and MM-010 treated with lenalidomide plus dexamethasone, 32 did not respond. Of the remaining 321 responding patients, 214 had a partial response (PR) or better and 107 patients had stable disease (SD). In this post-hoc sub-analysis, we first assessed the outcome of continuing treatment for ≤10 months vs. >10 months in all 321 patients who achieved SD or better, after they achieved their best response. In this landmark analysis, OS was measured from the time of achieving best response to death from any cause or to last contact. In a second analysis, we assessed the impact of early discontinuation due to adverse events or withdrawn consent on OS and TTP in all patients who achieved SD or better. Therefore, we excluded patients who discontinued treatment due to disease progression, death, or lack of efficacy. Patients who achieved SD or better and who continued on therapy were compared with those who discontinued. OS and TTP were assessed from time of randomization. Results: In the landmark analysis, of the 321 responding patients (≥PR, n=214; SD, n=107), 223 patients received treatment for ≤10 months after achieving their best response and 98 patients for >10 months after achieving their best response. Patients who continued therapy for >10 months after achieving their first best response had significantly longer OS vs. those who received therapy for ≤10 months (not reached vs. 23.4 months; p<0.0001). At 24 months after achieving their best response, significantly more patients were alive if they continued therapy >10 months vs. ≤10 months (93.8% vs. 48.4%, p<0.0001). In the second analysis, in order to evaluate the impact of discontinuation in patients achieving SD or better, we excluded 134 patients due to disease progression, death, or lack of efficacy. Of the remaining 187 responding patients, 72 discontinued treatment for AE (n=42) or withdrew consent (n=30), while the remaining 115 patients continued treatment. Median OS and TTP were significantly longer for patients who continued vs. those who discontinued treatment (median OS: not reached vs. 29.5 months, p<0.0001; median TTP: not reached vs. 13.6 months, p<0.0001). Conclusions: In patients achieving SD or better, prolonged duration of treatment was associated with significantly longer OS and TTP. In contrast, early discontinuation of treatment led to reduced OS and TTP. Therefore, efforts should be made to manage adverse events while maintaining patients on therapy. Furthermore, maintaining treatment with lenalidomide and dexamethasone after achieving the optimal response ensures a significant improvement in OS for patients with relapsed or refractory MM.
Dexamethasone Dose Adjustments Seem To Result in Better Efficacy and Improved Tolerability in Patients with Relapsed/Refractory Multiple Myeloma Who Are Treated with Lenalidomide/Dexamethasone (MM009/010 Sub-Analysis).
Abstract Background: The use of low-dose dexamethasone (Dex) in combination with lenalidomide (Len), an immunomodulatory compound, improves overall survival (OS) compared with high-dose Dex plus Len in patients (pts) with newly diagnosed multiple myeloma (MM) (Rajkumar et al. 2007). Two phase III randomised trials of pts with relapsed/refractory MM showed that Len/Dex had significantly better overall response (OR), complete response (CR), OS and time to progression (TTP) than Dex alone. Dex dose reductions were permitted in relation to severity of adverse events (AEs). We investigated the effect of Dex dose reductions on efficacy and tolerability of Len/Dex in relapsed/refractory MM. Methods: Data were pooled from the MM-009/010 studies for pts treated in the Len/Dex group who had an unchanged Len dose (n=233). Pts were treated with Len (25mg/day on day 1–21 of each 28-day cycle) and Dex 40mg on day 1–4, 9–12, and 17–20 (for the first four cycles). After four cycles, Dex 40mg/day was administered only on day 1–4. Dex dose reductions were: 40mg day 1–4 every 2 weeks (level -1), 40mg day 1–4 every 4 weeks (level -2), and 20mg day 1–4 every 4 weeks (level -3). Response to therapy, TTP, OS, and progression-free survival (PFS), as well as AEs were assessed. Response rate and TTP were based on data obtained before unblinding (June/August 2005 [MM-009/010]. Results: Of 233 pts in this post-hoc analysis, 177 pts were treated with Dex 40 mg/day throughout the study and 46 received Dex dose reductions. Forty-one pts received a dose reduction due to AEs. Baseline characteristics were balanced between treatment groups. Pts who received Dex dose reductions had a significantly higher OR rate, including a higher CR, compared with those who received standard Dex dose (Table). Pts in the Dex reductions group had significantly longer median TTP, median OS, and median PFS, compared with those who received Dex at the assigned dose. At the end of the study, rates of serious AEs, grade 3–4 AEs, treatment-related AEs and withdrawals because of AEs were comparable between pts who received Dex dose reductions and those who received an unchanged Dex dose. Although most Dex dose reductions were made for an AE, by reducing the dose pts were able to maintain a similar safety profile to those who did not require dose reductions. Grade 3–4 haematological AEs in pts who received Dex dose reductions and those who did not were neutropenia (23.7% and 32.6%, respectively), thrombocytopenia (8.5% and 6.8%, respectively) and anaemia (6.8% and 6.2%, respectively). No febrile neutropenia was reported in these pts. Conclusion: Dex dose reductions improved the efficacy of Len/Dex without affecting tolerability in pts with relapsed/refractory MM. Len/Dex Dex unchanged (n=177) Dex reduced (n=46) P *Most conservative median estimate obtained assuming all censored patients die right right after the censor date Response, % OR 50.8 69.6 <0.05 CR 13.0 23.9 <0.01 nCR 19.8 37.0 <0.01 PR 18.1 8.7 <0.01 Median TTP, weeks* >24.1 >59.9 0.002 Median OS, weeks* >109.7 >121.9 0.19 Median PFS, weeks* >24.1 >59.9 0.001
Preliminary Results from a Phase II Study of Lenalidomide Monotherapy in Relapsed/Refractory Aggressive Non-Hodgkin’s Lymphoma.
Abstract Background: Lenalidomide (Revlimid®), an immunomodulatory drug (IMiD®), was recently approved in the US for treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes associated with a deletion 5q[31] cytogenetic abnormality. Lenalidomide also has demonstrated activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma while thalidomide, a less potent IMiD®, has activity in non-Hodgkin’s lymphoma as both monotherapy and in combination with rituximab. Aim: To assess the safety and activity of lenalidomide monotherapy in subjects with relapsed/refractory aggressive non-Hodgkin’s lymphoma (NHL). Methods: Subjects with relapsed/refractory aggressive NHL following at least 1 prior treatment regimen with measurable disease are eligible. Subjects receive 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continue therapy for 52 weeks as tolerated or until disease progression. Response and progression are evaluated using the IWLRC methodology. Results: As of July 25, 2006, 32 subjects of a planned 40 have enrolled and 31 have received drug. Twenty-two subjects are currently evaluable for tumor response. The median age of the 22 response-evaluable subjects is 65 (46–83) and 13 are female. Histology is diffuse large B-cell lymphoma [DLBCL] (n=12), follicular center lymphoma grade 3 [FL] (n=3), mantle cell lymphoma [MCL] (n=5) and transformed [TSF] (n=2). Median time from diagnosis to lenalidomide monotherapy is 2.3 (0.7–7) years and median number of prior treatment regimens per subject is 2 (1–6). Seven subjects (32%) exhibited an objective response (2 complete responses unconfirmed (CRu) and 5 partial responses (PR)), 6 had stable disease (SD) for a tumor control rate (TCR) of 59% and 9 progressive disease (PD). Responses were produced in each of the aggressive histologic subtypes studied: DLBCL (3/12), FL (1/3), MCL (2/5) and TSF (1/2). Five of 11 subjects (45%) with 1–2 prior treatment regimens had an objective response, as did 2 of 3 subjects (67%) who had received a prior stem cell transplant. Median time-to-response was 2 months. Grade 3 or 4 adverse events occurred in 18 of 31 (58%) subjects receiving drug. These were predominantly Grade 3 hematological events (neutropenia, thrombocytopenia) with only 4 subjects (13%) experiencing a Grade 4 adverse reaction. Conclusion: Preliminary results indicate that lenalidomide monotherapy is active with manageable side effects in relapsed/refractory aggressive NHL.
Long Term Clinical Benefit of Lenalidomide (Revlimid) Treatment in Patients with Myelodysplastic Syndrome without Del 5q Cytogenetic Abnormalities.
Abstract Background: MDSs are clonal hematopoietic stem cell malignancies characterized by cytopenias resulting from ineffective hematopoiesis. A phase 2 study of lenalidomide (MDS-002) demonstrated hematological improvement in patients with MDS without an associated deletion 5q cytogenetic abnormality (List AF, et al. Haematologica2006;91[suppl1]:379[abst 1032]). We now report multicenter results after 〉2 yrs follow-up. Methods: A total of 214 pts with transfusion-dependent anemia were categorized into the following IPSS MDS risk groups after central review of bone marrow morphology, karyotype, and peripheral blood findings: Low/Int-1 (168 [78%]); Int-2/High (8 [4%]); and unclassified (38 [18%]). Patients were unclassified for missing or inadequate marrow studies for central review (morphology [29] or cytogenetic [7]) or other diagnoses (AML [1], atypical CML [1]). Patients were evaluated for frequency and duration of red blood cell transfusion independence (RBC-TI) (IWG criteria), hemoglobin (Hgb) response, and safety. The starting dose of lenalidomide was 10 mg (daily or daily × 3 wks q28d cycle). Results: Overall, 56 (26%) of 214 enrolled patients achieved RBC-TI. Median time to RBC-TI was 5 wks, median duration of RBC-TI response was 41.0 wks (range, 8.0–136.4), and median Hgb increase achieved during RBC-TI was 3.2 g/dL (range, 1.0–9.8). An additional 36 patients experienced a ≥ 50% reduction in RBC transfusions (overall hematological improvement in 92 [43%] patients). Overall, 47 (22%) patients had an abnormal karyotype at baseline and 9 (19%) patients achieved a cytogenetic response (4 complete). The most common drug-related grade 3/4 adverse events (AEs) were neutropenia and thrombocytopenia (25% and 20%, respectively). Deep vein thrombosis occurred in only 2 (1%) patients. The duration of RBC-TI was ≥ 52 weeks in 21 (38%) patients. Among these 21 patients, 14 (67%) did not require a lenalidomide dose reduction during the first 52 weeks of treatment. Analyses of response variables will be presented. Dose-limiting neutropenia/thrombocytopenia was not reported after 52 weeks. The most commonly reported AEs after 52 weeks were mild-moderate diarrhea and fatigue (38% and 29%, respectively). Conclusion: Lenalidomide is an active, well-tolerated treatment in MDS patients with transfusion-dependent anemia that is not associated with a deletion 5q abnormality. The rate of erythroid hematologic improvement and duration of RBC-TI is encouraging and offers a possible alternative to cytokine therapy.
Phase II Study of the Combination of Low-Dose Thalidomide, Prednisone, and Oral Cyclophosphamide (TPC Regimen) in the Treatment of Anemia, Splenomegaly, and Constitutional Symptoms Associated with Myelofibrosis with Myeloid Metaplasia (MMM).
Abstract BACKGROUND: We have previously reported on the therapeutic value of low-dose thalidomide in combination with prednisone (THAL-PRED) for the treatment of both anemia and thrombocytopenia in MMM (Blood2003;101:2534), with response rates of 62% and 75% for each cytopenia respectively. Alkylators have long been shown to have palliative benefit in MMM, however are used judiciously as long-term use could increase likelihood of leukemic transformation. Additionally, oral cyclophosphamide has been shown to synergize with thalidomide and steroids in the treatment of myeloma (Garcia-Sanz et. al. Leukemia2004;18:856–863). In the current study, we investigated the value of adding oral cyclophosphamide to THAL-PRED for MMM (TPC). METHODS: Study eligibility criteria included a histologically confirmed diagnosis of MMM and either severe anemia (hemoglobin < 10 g/dL) or symptomatic splenomegaly. Protocol treatment was initiated with 50 mg of oral thalidomide (THAL) daily, oral cyclophosphamide (CTX) 25 mg daily for three months, and a three month prednisone taper starting at 0.5 mg/kg/day for the first month followed by a 50% reduction for the second months and a further 50% reduction for the third and final month of treatment with prednisone. Patients with a demonstrable clinical response after three months were able to remain on thalidomide alone as maintenance. Responses were assessed by the International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) criteria for MMM clinical responses (Tefferi et. al. Blood 2006; epub May 2006). RESULTS: 13 patients were enrolled to the trial (median age 73 years, range, 46–80; 7 males). Six patients (46%) completed the planned three cycles (i.e. 12 weeks) of treatment, the remaining seven patients discontinued treatment early for the following reasons: progression (n=3), patient choice (n=2), other medical problem (n=1) and died on study (n=1). After the initial 3 months of treatment, 3/13 (23%) patients evidenced a response (n = 1) or stable disease (n = 2) and continued on an additional three months of THAL alone. At enrollment, nine patients (69%) were anemic (8 of whom (62%) were red cell transfusion dependent). Ten patients (77%) were at least moderately thrombocytopenic (platelet count < 100 x 109//L). Eight patients (62%) had palpable hepatomegaly/splenomegaly, and five patients (38%) had severe constitutional symptoms (night sweats). According to IWG-MRT criteria for MMM the best responses observed from therapy was a CI (clinical improvement) in 2 individuals (one each for anemia (1/9 patients (11%); and thrombocytopenia (1/10 patients (10%)). No clear responses in organomegaly or constitutional symptoms were observed. The regimen overall was well tolerated with toxicities in excess of grade 2 all being related to myelosuppression (anemia (n=2), neutropenia (n=2), and thrombocytopenia (n=3)). CONCLUSIONS: This phase II study of combination therapy with thalidomide-prednisone-cyclophosphamide in patients with MMM strongly suggests that the addition of the alkylator cyclophosphamide largely negates the clinical benefits of THAL-PRED. This observation supports the potential immunologic mechanism of THAL-PRED benefit in MMM, and cautions against potential combinations of immunological and cytotoxic therapy in this disorder.
Early Results from a Phase II Study of Lenalidomide Monotherapy in Relapsed/Refractory Indolent Non-Hodgkin’s Lymphoma.
Abstract Background: Lenalidomide (Revlimid®), an immunomodulatory drug (IMiD®), was recently approved in the US for treatment of relapsed/refractory multiple myeloma and myelodysplastic syndromes associated with a deletion 5q[31] cytogenetic abnormality. Lenalidomide also has demonstrated activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma while thalidomide, a less potent IMiD®, has activity in non-Hodgkin’s lymphoma (NHL) as both monotherapy and in combination with rituximab. Aim: To assess the safety and efficacy of lenalidomide monotherapy in subjects with relapsed/refractory indolent NHL. Methods: Subjects with relapsed/refractory indolent NHL following at least 1 prior treatment regimen with measurable disease are eligible. Subjects receive 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continue therapy for 52 weeks as tolerated or until disease progression. Response and progression are evaluated using the IWLRC methodology. Results: As of July 25, 2006, 23 subjects of a planned 40 have enrolled and received drug. Fifteen subjects are currently evaluable for tumor response. The median age of the 15 response-evaluable subjects is 64 (54–82) and 5 are female. Histology is small lymphocytic lymphoma [SLL] (n=8), follicular center lymphoma grades 1,2 [FL] (n=5) and nodal marginal B-cell lymphoma [NML] (n=2). Median time from diagnosis to lenalidomide monotherapy is 7.6 (3–14) years and median number of prior treatment regimens per subject is 3 (1–17). Two subjects (13%) exhibited an objective partial response (PR) at four months. Both responses, one FL and one NML, occurred in subjects with substantial tumor burden of 61.8 cm2 and 80.3 cm2, respectively. The 4-month time-to-response for these indolent NHL subjects is longer than the 2-month median time-to-response in aggressive NHL subjects (n=7) following lenalidomide monotherapy. Seven patients had stable disease (SD) for a tumor control rate (TCR) of 60% and 6 had progressive disease (PD). Grade 3 or 4 adverse events occurred in 9 (39%) subjects. These were predominantly Grade 3 hematological events (neutropenia, thrombocytopenia) with only 3 subjects (13%) experiencing a Grade 4 adverse reaction (all neutropenia). Conclusion: Early results of lenalidomide monotherapy in indolent NHL show evidence of activity with a safety profile similar to that established previously in other hematological malignancies.
Long-Term Clinical Benefit of Lenalidomide (Revlimid) Treatment in Patients with Myelodysplastic Syndrome and Chromosome Deletion 5q.
Abstract Background: Myelodysplastic syndromes (MDS) are hematological disorders characterized by chronic anemia, and are often refractory to cytokine therapy. Two phase 2 studies evaluating lenalidomide in MDS (MDS-001 and MDS-003), demonstrated a high frequency of erythroid response in patients with a chromosome 5q31 deletion (List AF et al., N Eng J Med2005; 352:549–557 and List AF et al., in press). Herein we report on the durability of response with long term follow-up approaching 4 years. Methods: All enrolled subjects were evaluated for frequency and duration of red blood cell transfusion independence (RBC-TI), change in hemoglobin (Hgb), pathologic and cytogenetic response, and safety. Results: Ten 5q31- patients achieved a cytogenetic and/or major erythroid response in MDS-001. Four of these patients have maintained a major response for at least 2 years (range 2.2 to 3.7 years). In MDS-003, 99 (67%) of 148 enrolled patients achieved RBC-TI. Of the 99 responders 83 were Low/Int-1, 3 were Int-2/High and 13 were not classified. Median increase in Hgb from baseline to maximum achieved during RBC-TI was 5.4 g/dL (range 1.1, 11.4). The estimated median duration of response was 115.9 weeks, and 52 (53%) of 99 responders remain on study with ongoing RBC-TI response as of 30 June 2006. Duration of response was at least 52 weeks for 63 (64%), 78 weeks for 52 (53%), and 104 weeks for 36 (36%) of 99 responding patients. Variables (or co-variates) associated with longer duration of TI in multivariate analysis included low baseline transfusion requirement (<4 units per 8 wks, p=0.002), 5q- syndrome (p=0.01) and low IPSS (p=0.02) classifications. Among 85 evaluable patients, major cytogenetic responses were achieved in 37 (44%) and minor responses in 24 (28%). Cytogenetic responses occurred in patients with complex karyotypes as well as those with an isolated 5q31 deletion. The frequencies of major and minor cytogenetic responses were similar among patients with and without 5q- syndrome. The most common drug-related adverse events (AE) were Grade 3/4 neutropenia and thrombocytopenia, reported in 87 (59%) and 74 (50%) of 148 patients, respectively although hematologic AEs led to study discontinuation in only 13 (9%) of patients. Pneumonia was the only serious adverse event that occurred in >10% of patients (15/148; 10%). Adverse events were manageable through supportive treatment and dose reduction. Conclusion: Lenalidomide is an effective treatment in MDS patients with an associated chromosome 5q31 deletion, with RBC-TI and major erythroid response maintained for median duration > 2 years.