ALBERT

Description: Abstract 2399 The quality and depth of response particularly achievement of complete remission (CR) have been associated with significant improvement in progression free survival (PFS) and overall survival in multiple myeloma patients undergoing autologous stem cell transplant. Achievement of CR is considered a valid surrogate endpoint for survival in clinical trials for patients with multiple myeloma. We performed a phase II study investigating the role of sequential bortezomib/dexamethasone followed by thalidomide/dexamethasone as maintenance therapy post single autologous PSCT. The objectives were to examine the feasibility, toxicities, CR, PFS and overall survival rates. Within 4–8 weeks of autologous PSCT using melphalan 200mg/m2, pts received weekly bortezomib (bor) at 1.3mg/m2 /wk × 3 weeks with 1 week rest and dexamethasone (dex) at 40mg/d × 4 d for 6 months, followed by thalidomide (thal) at 50 –200mg/d and dexamethasone (dex) at 40mg/dx4 d for 6 more months. Single agent thalidomide was then continued until disease progression. Between March 2008 and June 2010, forty-five pts were enrolled. Median age was 54 years (29-71). Median time from diagnosis was 6.1 mo. (3.5 – 145.9). Disease stage at diagnosis; by Salmon-Durie (I/II/III 2/8/34/1 not available) and by ISS (I/II/III 18/14/8/ 5 not available). Pts received prior induction treatment with thal/dex (15), bortezomib based (27) and lenalidomide based regimens (10). Median B2M at enrollment was 1.8 mg/L (1.05 -5.3). Disease status at enrollment included complete remission (CR) (11), very good partial response (VGPR) (11), partial response (PR) (23). Six pts had chromosome 13 abnormalities (1 pt by karyotype and 5 pts by FISH), 2 pts had t 4;14 (one with concurrent ch 17 p del) and 3 pts had complex cytogenetic abnormalities. Results: Forty-five pts have been enrolled and undergone transplant. Five pts were unable to start planned maintenance therapy due to development of grade II or more neuro toxicities (4), and persistent thrombocytopenia (1) after PSCT. Thirty nine pts started maintenance bor/dex within 4–8 weeks of PSCT. One pt is too early for maintenance therapy. Twenty-five pts have completed the planned 6 months of bor/dex. Ten pts stopped bor/dex because of low WBC (2), PN (4), diagnosis of adrenal cancer (1), myocardial infarction (MI) (1), and relapse (2). Six pts are still receiving maintenance bortezomib. With a median F/U of 8.5 mo. (0.2 -24.0) twelve of 44 evaluable pts (27%) have achieved CR post PSCT and 17 of 33 evaluable pts (51%) have achieved CR after bor/dex on an intention to treat (ITT) analysis. Fifteen of 25 pts (60%) who have completed 6 months of bor/dex have achieved CR. Nine of 25 pts (36%) have upgraded their response with bor/dex. Eight pts (24%) could not complete bortezomib due to toxicities. At one year post PSCT fourteen of 28 evaluable pts (50%) remain in CR. Six pts have relapsed of whom 2 died of relapsed myeloma (leptomeningeal disease 1 pt). One pt experienced MI while receiving bortezomib (grade IV). Grade III toxicities have occurred in 17 pts; low platelet (1), asthenia (2), mood alteration (1), GI (severe constipation due to partial bowel obstruction on thalidomide) (1), skin rash (1), hyperglycemia (1), lymphopenia (10), sinus bradycardia (1), elevated triglyceride (1), DVT (1), low phosphate (3), leukopenia (1), edema (1). Sixteen pts had peripheral neuropathy (PN) grade I prior to start of bortezomib. Only 8 pts have developed new PN on the study and all are grade I-II. No patient has experienced grade III-IV PN. Median bortezomib dose is 1.3 mg /m2 per week. Conclusion: Prolonged weekly bortezomib maintenance therapy is well tolerated and can upgrade response post single autologous PSCT with no severe peripheral neuropathy. Fifty one percent of pts have achieved CR and 36% have upgraded their response after six months of bortezomib/dexamethasone therapy suggesting this is an active maintenance strategy post PSCT. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4982 Lenalidomide is an immunomodulatory agent that stimulates T-cell activation, enhances natural killer cells and inhibits cytokines, as tumor necrosis factor-alpha. It is FDA-approved for use in both transfusion-dependent myelodysplastic syndrome, especially 5q deletion syndrome and refractory and relapsed multiple myeloma. The known side effects are myelosuppression, diarrhea/constipation, fever, fatigue, rash and thromboembolism, while pulmonary complications are rarely reported. We present a patient with myelodysplastic syndrome on lenalidomide with acute pulmonary toxicity. A 63-year-old Caucasian man was diagnosed with low-intermediate risk myelodysplastic syndrome with 5q deletion after presenting with anemia and thrombocytopenia. He was started on lenalidomide at 21mg daily dose but after 5 days began to develop dyspnea on exertion, cough and fever. He was admitted for treatment of community acquired pneumonia. Physical examination revealed a middle aged man in respiratory distress. Oxygen saturation on room air was 86%. Chest examination revealed dry crackles. Heart sounds were regular without murmurs or gallops. Laboratory tests revealed hemoglobin of 8.6g/dl, normal white count at 10,000 and platelets of 7,000/uL. BNP and echocardiogram were normal and chest radiography was initially unremarkable. He was started on antibiotics but developed respiratory failure requiring endotracheal intubation and mechanical ventilation. CT scan of the chest showed diffuse interstitial reticulonodular opacities most prominent at the apices with scattered ground glass attenuation. Cultures from blood, sputum, urine and stool and brochoalveolar lavage did not reveal an infectious source. Broad spectrum antibiotics and antifungals were withheld. Clinical and radiologic improvement was noted after withdrawal of lenalidomide and initiation of steroids. He was persistently transfusion-dependent hence lenalidomide was reintroduced. Within 6 days of lenalidomide, respiratory symptoms recurred. He later improved after withdrawal of the offending drug. Our myelodysplastic patient developed acute respiratory failure after lenalidomide introduction which improved with steroids and drug withdrawal. He had symptom recurrence after reintroduction of lenalidomide. The exposure history, clinical and radiological examination, positive challenge test with exclusion of other etiologies support the diagnosis of lenalidomide-induced hypersensitivity pneumonitis. This is the third reported case of lenalidomide-induced hypersensitivity pneumonitis and it is likely that this entity is underdiagnosed due to concurrent steroid use especially in myeloma patients. Clinicians should be aware of this potential complication in patients who present with fever, hypoxemia and diffuse pulmonary infiltrates unresponsive to broad spectrum antibiotics as this disease is reversible if diagnosed early. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3403 While imatinib and other tyrosine kinase inhibitors (TKIs) are effective in the treatment of chronic myeloid leukemia (CML), patients can fail all of these therapies. One reason for this is that TKIs have only limited activity against CD34+CD38- leukemic stem cells in CML. Recently, we demonstrated that the IL3 receptor (IL3R) is highly expressed on CD34+38- Bcr-Abl(+) CML stem cells and represents an attractive target for therapeutic intervention (ASH 2009 114: Abstract 2172). IL3R overexpression has also been demonstrated on leukemic stem cells of other hematological malignancies including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Moreover, IL3R is a clinically validated target, as demonstrated by anti-tumor activity including complete and partial responders with the IL3R targeting agent, SL-401, in a Phase I clinical trial of patients with advanced AML and MDS. However, IL3R has not yet been fully investigated as a therapeutic target in CML. Accordingly, in this study, we examined whether targeting IL3R with SL-401 and SL-501, two recombinant biologic agents, could eradicate CML stem cells. SL-401, which is comprised of human IL3 recombinantly conjugated to diphtheria toxin (DT), has been shown to eradicate AML stem cells in both in vitro and in vivo experimental systems. SL-501 is a second generation IL3R targeting agent that contains an optimized IL3 sequence, which increases its affinity for IL3R. Both SL-401 and SL-501 are directed to IL3R on the leukemic cell surface, thereby triggering receptor-mediated endocytosis, inhibition of protein synthesis, and induction of apoptosis. In this study we demonstrated that SL-401 and SL-501 significantly inhibited the growth of CML cells (p ≤ 0.00009) and induced apoptosis (p ≤ 0.003) in 14 primary CML samples. In six primary CML samples, these agents reduced the absolute numbers of viable CD34+/CD38-/CD123+ CML progenitor cells (p ≤ 0.03) by inducing apoptosis (52.2 ± 9.3% and 65.5 ± 10.7% for SL-401 and SL-501, respectively). To evaluate the effect of these agents on the growth of the most primitive stem cells, CML blasts were pretreated with IL3R targeted agents for 24 h and grown in the Long-Term Culture-Initiating Cell assay. SL-401 and SL-501 significantly reduced formation of hematopoietic colonies from primary CML samples in a dose-dependent manner (colony formation reduced by 54.4–80.5% and 66.6–75.1% for SL-401 and SL-501, respectively; p ≤ 0.009). Similar results were obtained when growth of CML progenitor cells was assessed in the Colony Forming Cell assay (colony formation reduced by 54.0–70.2% and 71.1–84.4% for SL-401 and SL-501, respectively; p ≤ 0.0002; N = 6). Notably, the majority of primary samples were obtained from patients resistant to TKIs (12 of 15) and/or harboring an abl mutation including T315I (7 of 15). Moreover, the combination of these IL3R targeted agents with imatinib demonstrated synergistic effects (CI 〈 1.0) against the KBM5 CML cell line and its TKI resistant KBM5STI subline, which harbors the T315I mutation. In addition, combination of these IL3R directed agents with imatinib further enhanced the apoptotic rate of primary CML cells (N = 5). Importantly, both SL-401 and SL-501 demonstrated high anti-leukemic activity in vivo when NOD/SCID/IL2Rg-KO mice were transplanted with leukemic cells from patients with primary myeloid blast crisis CML (median survival: vehicle = 37 d, SL-401 = 48 d, and SL-501 = 57 d; p = 0.0005). In conclusion, these data indicate that SL-401 and SL-501, two active IL3R directed agents, represent a novel therapeutic modality for the selective targeting of CML stem cells. Combinations of these agents with TKIs may also benefit CML patients who are resistant to TKI treatment by reducing and/or eliminating leukemic stem cells. Disclosures: Off Label Use: We will discuss the use of SL-401 and SL-501 drugs in CML. Frankel:Stemline Therapeutics: Research Funding. Konopleva:Stemline Therapeutics: Research Funding.

Description: Abstract 3298 Background and Rationale: SL-401 (DT388IL3) is a novel cancer stem cell (CSC)-directed recombinant biologic agent that targets the interleukin-3 receptor (IL-3R). IL-3R is over-expressed on acute myeloid leukemia (AML) stem cells relative to normal hematopoietic stem cells. IL-3R is also over-expressed on AML blasts. In pre-clinical studies, SL-401 targets and eradicates CSCs and tumor bulk in both in vitro and in vivo assays, and prolongs survival of immunosuppressed mice harboring human AML xenografts. Study Design: A Phase I dose escalation study was undertaken in 74 patients with relapsed or refractory adult AML (n=56), de novo poor risk elderly AML (n=11), or high risk myelodysplastic syndrome (MDS) (n=7). Thirty-three patients were 〉/= 2nd salvage. Cytogenetics were unfavorable (36%), intermediate (59%), favorable (0%), and not determined (5%). The median age was 65 years (range, 24–84). Patients received SL-401 via a 15 minute intravenous infusion in one of two dosing regimens for one cycle to determine the maximum tolerated dose (MTD) and to evaluate clinical activity. In Regimen A, 45 patients received doses ranging from 4 to 12.5 ug/kg every other day for up to six doses. In Regimen B, 29 patients received doses ranging from 7.1 to 22.1 ug/kg daily for up to 5 doses. Safety: SL-401 was well-tolerated at clinically active doses. Grade 1–2 hypoalbuminemia was common (68%) but manageable and not dose-limiting. Other less common grade 1–2 adverse events (AEs) included fever and chills, largely infusion-related. Grade 〉/= 3 AEs included transaminase elevations (20%), mostly transient, and vascular leak (4%) which was the dose limiting toxicity (DLT) at 22.1 ug/kg daily × 5. The MTD was established at 16.6 ug/kg daily for 5 doses; no MTD was defined for the every other day schedule. Notably, there was no treatment-related delayed recovery of the bone marrow. This is consistent with the known over-expression of the drug's target, IL-3R, on leukemia versus normal hematopoietic stem cells. Absolute neutrophil count and hemoglobin remained stable, and near or above baseline pre-treatment levels, throughout therapy and up to day 30 post-infusion. Mean platelet counts were 58,000/uL pre-treatment, 30,000/uL at day 15, and back to baseline by day 30. Efficacy: Overall, we observed 2 complete remissions (CRs), 4 partial responses (PRs) and 14 minor responses (MRs) including 4 with 〉50% reduction in blasts. In addition, anti-tumor activity, defined as blast reductions or disease stabilization, was seen in 46% of patients with relapsed or refractory AML, 55% of poor risk elderly AML, and 43% of high risk MDS patients. Durable complete remissions (CRs) were induced in 2 patients with chemorefractory AML. One patient, who sustained a CR of 〉15 months duration, had a previous history of refractory AML, including two stem cell transplants, and had relapsed for a third time prior to entry onto this study. The second patient had a sustained CR of 8 months duration, after failing standard AML induction chemotherapy. This is consistent with the dual mechanism of action of SL-401 targeting both blasts and leukemia stem cells. In addition, the median survival of 〉/= 2nd salvage AML patients was 3.2 months (95% CI: 2.0, 8.4) and the 12 months overall survival was 22% (95% CI: 5.1, 45.7) which is favorable compared with historical 12-months survival of 2–8%. Also of note, SL-401 demonstrated a clinical anti-CSC effect as evidenced by a decrease in CSC activity in patient bone marrows (n=3), as determined by an ex vivo colony formation assay pre- and post-SL-401 treatment. Conclusions: SL-401 demonstrated clinical activity, including durable CRs as well as blast reductions and disease stabilization. Preliminary signals for a clinical anti-CSC effect and survival benefit in heavily pre-treated patients were also observed. SL-401 had a favorable safety profile and exhibited no myelosuppression. Given these promising results, Phase II studies of SL-401 are planned in patients with advanced AML and MDS. In parallel, SL-401 will be studied in additional Phase I trials as both single agent and in combination with other agents in IL-3R+ leukemias including chronic myeloid leukemias (CML). Disclosures: Konopleva: Stemline: Research Funding. Cirrito:Stemline: Employment, Equity Ownership, Patents & Royalties. Niecestro:Stemline: Consultancy, Equity Ownership. Bergstein:Stemline: Board of Directors, Employment, Equity Ownership, Patents & Royalties. Frankel:Stemline: Research Funding.

Description: Abstract 3957 Background: The indolent (follicular, marginal zone and mantle cell) lymphomas tend to recur with decreasing intervals of remission after standard chemotherapy. New modalities of treatment are necessary. Vorinostat (SAHA) is an orally administered hydroxamic acid histone deacetylase inhibitor with activity against class I and II deacetylases. An earlier study of single agent vorinostat showed promising activity in indolent lymphomas, thus a follow up study combining vorinostat with rituxan was performed. Methods: We report the results of the planned interim analysis (first stage) of a two-stage phase II study of oral vorinostat combined with rituximab in patients with newly diagnosed, relapsed or refractory (to chemotherapy and/or rituximab) follicular, marginal zone, or mantle cell lymphoma. Vorinostat is given at 200 mg PO twice daily for 14 consecutive days on a 21 day cycle. Rituximab is given on day one of each cycle. CT scanning and/or FDG-PET are performed after every three cycles, as is marrow biopsy for those with marrow involvement at time of entry into study. Patients may have received up to four prior chemotherapy regimens including tositumomab or ibritumomab; previous transplant is allowed. 17 eligible patients (8 female, 9 male) were accrued during the first stage of accrual. The median age at treatment was 60 years (range 44–71). Histologies represented: mantle cell (MC)-2, marginal zone (MZL)-1, and follicular lymphoma (FL)-14. Treatment was well tolerated. Grade 4 toxicities possibly attributable to study drug include neutropenia (n=1), thrombosis (n=3), and platelet (n=1). Grade 3 possibly related toxicities include fatigue (n=5), hyperglycemia (n=3), dehydration (n=2), and one each of platelets, hypophosphatemia, hypotension, infection, diarrhea, syncope, and thrombosis (nonclinical pulmonary embolism discovered incidentally on CT scan). Results: The overall formal response (CR+PR) rate thus far is 35% (6/17), with a response rate of 43% (6/14) for patients with FL, and no formal responses seen in mantle cell (0/2) or MZL (0/1). By the current Cheson criteria, 5 patients achieved complete remission (CR), and 1 patients achieved partial remission (PR). One patient (FL) with a CR relapsed 14 months after treatment initiation. The remaining 5 responders have not relapsed, at 4, 9, 13, 16 and 21 months. The median PFS has not been reached, and only 1 responder has progressed to date at 9 months (patient with FL). Conclusions: The combination of the histone deacetylase inhibitor vorinostat with rituximab is well tolerated, and shows encouraging activity against relapsed/refractory indolent lymphoma The study has passed interim analysis and will proceed to full accrual of 33 patients. Support: Supported in part by a research grant from the Investigator Initiated Studies Program of Merck Sharp & Dohme Corp. Disclosures: Kirschbaum: Merck: Honoraria, Research Funding. Off Label Use: clinical trial of vorinostat in indolent lymphomas. Pullarkat:Novartis Pharma: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Description: Abstract 528 Background: Allogeneic Stem Cell transplantation remains the only curative treatment modality for hematologic malignancies such as AML, ALL, and MDS. Reduced intensity regimens were designed which replaced the alkylating agent cyclophosphamide with the purine nucleoside antimetabolite, fludarabine, a potent immunosuppressive with a substantially milder toxicity profile. Clofarabine is a purine nucleoside analogue designed to exploit a double halogen strategy which confers resistance to adenosine deaminase, increases stability and bioavailability and makes the drug more efficient than fludarabine at inhibiting ribonucleotide reductase (RNR) and disrupting mitochondrial function, leading to apoptosis. Clofarabine is potentially a superior antileukemic agent as compared with fludarabine, thus enhancing the activity of the conditioning regimen. Aims: To evaluate a novel clofarabine containing regimen as conditioning for adult fully matched allogeneic stem cell transplant. Methods: phase I dose escalation: clofarabine (dose level 1 = 30 mg/m2, dose level 2 and 3 =40 mg/m2) IV daily days –7 to day –3 infused over 30 minutes IV, plus Melphalan (dose level 1 and 2, 100mg/m2, dose level 3, 140 mg/m2) administered over 30 minutes IV on day –2. Related or unrelated allogeneic stem cells were infused on day 0. GVHD prophylaxis: initially cyclosporine plus mycophenolate, then tacrolimus plus sirolimus was adopted as per City of Hope standard of care. Patients (pts) age ≥ 18 years with AML, ALL, MDS in either CR1, CR2 or in relapse (up to 50% marrow blasts), not deemed eligible for standard transplant regimens by the attending physician, or at high risk for relapse, are eligible. Results: 16 eligible pts, all with AML, have been treated thus far, 7,males, 9 females, with a median age of 63 years (30 – 66). Seven pts were in CR1, 2 pts were in CR2, 4 pts where induction failures, and 3 pts were in first relapse. Grade 3 non-hematologic toxicities included elevation of transaminases, diarrhea, and hyponatremia. No dose limiting toxicities (DLT) were seen in the 3 pts treated at dose level 1. One patient in dose level 2 died prior to engraftment due to hepatic, renal, and infectious toxicities; that dose level has been expanded to 12 patients and no further DLTs were seen. The first patient treated at dose level 3 developed multiorgan failure and died prior to engraftment. Given the excellent results seen in the two previous cohorts we opted not to dose escalate any further patients beyond clofarabine 40 mg/m2 and melphalan 100 mg/m2. Three patients with primary induction failure received an unrelated donor graft and had complete engraftment and obtained remission. The median time to ANC recovery is 14 days and to platelet recovery is 16 days (see table). Mild acute skin graft versus host disease (GvHD) was seen in five patients, mild chronic GvHD in four patients, one patient developed severe chronic GVHD of the liver and died at day 201 from CNS bleed due to tacrolimus-sirolimus related TTP-HUS. Of the 14 patients that successfully completed transplant (no DLT or engraftment difficulty), only one patient has relapsed, with median follow-up of 10.5 months (range 4–24). Conclusion: The combination of clofarabine and melphalan is a well tolerated reduced intensity conditioning regimen with enhanced anti-leukemia activity leading to complete engraftment of related and unrelated fully matched allogeneic stem cells. Complete engraftment with prolonged disease free survival was seen at both dose levels 1 and 2. Disclosures: Off Label Use: clofarabine as a component of the conditioning regimen for allogeneic transplant.