Abstract: To address the global burden of sickle cell disease (SCD) and the need for novel therapies, the American Society of Hematology partnered with the US Food and Drug Administration to engage the work of 7 panels of clinicians, investigators, and patients to develop consensus recommendations for clinical trial end points. The panels conducted their work through literature reviews, assessment of available evidence, and expert judgment focusing on end points related to: patient-reported outcomes (PROs), pain (non-PROs), the brain, end-organ considerations, biomarkers, measurement of cure, and low-resource settings. This article presents the findings and recommendations of the PROs, pain, and brain panels, as well as relevant findings and recommendations from the biomarkers panel. The panels identify end points, where there were supporting data, to use in clinical trials of SCD. In addition, the panels discuss where further research is needed to support the development and validation of additional clinical trial end points.

Abstract: IMGN779 is a CD33-targeted ADC utilizing DGN462, a novel DNA-alkylating agent consisting of an indolino-benzodiazepine dimer containing a mono-imine moiety. CD33 is expressed on the surface of about 90% of AML cases, with elevated levels of CD33 found in cases having molecular markers associated with poor prognosis, including mutations in FMS-like tyrosine kinase 3 (FLT3). The internal tandem duplication mutation (FLT3-ITD) is the most common FLT3 mutation, present in about 20-25% of AML cases. Patients with FLT3-ITD AML have a worse prognosis than those with wild-type (WT) FLT3, with an increased rate of relapse and a shorter duration of response to induction chemotherapy. IMGN779 was found to demonstrate targeted activity against AML cell lines in vitro, with IC50 values ranging from 2-3,000 pM. The MV4-11 cell line, which has a FLT3-ITD mutation, was the most sensitive to IMGN779 of the cell lines tested, with an IC50 of 2 pM. We evaluated the in vivo activity of IMGN779 against MV4-11 xenografts in SCID mice; IMGN779 was highly active (T/C = 1 %) at a single dose of 0.6 mg/kg (conjugate dose, 10 µg/kg DGN462 dose), resulting in complete tumor regressions (CR) in 3/6 animals and partial regressions (PR) in 6/6 animals. A DGN462-ADC to a non-relevant target was inactive (T/C = 95%) at the same dose, demonstrating that the activity of IMGN779 was due to its CD33 targeting. IMGN779 has previously been shown to be highly active against AML xenograft models without FLT3-ITD mutations, at minimally efficacious doses of 0.6 mg/kg (10 µg/kg DGN462), demonstrating that the presence of FLT3-ITD does not confer resistance to IMGN779 treatment. IMGN779 was also highly active in vitro against primary patient AML cells isolated from peripheral blood or bone marrow samples. Patient AML cells with FLT3-ITD were more sensitive to IMGN779 compared with FLT3 WT AML samples. IC50 values in FLT3-ITD samples ranged from 10 to 300 pM. CD33 expression was generally greater on FLT3-ITD leukemic blast cells than on FLT3 WT blasts, which likely contributed to their increased sensitivity to IMGN779. In long term cultures, IMGN779 showed a dose dependent decrease in leukemic stem cell (LSC) colony formation using an AML patient sample with both FLT3-ITD and NPM1 mutations, which are an even worse prognostic marker than FLT3-ITD alone. In contrast, colony formation increased in normal bone marrow, indicating that normal hematopoietic stem cells (HSCs) were spared. The differential expression of CD33 on LSC compared to HSCs makes CD33 an attractive target for treatment of AML, with the potential to eliminate LSCs and, thus, minimal residual disease in FLT3-ITD AML. The potent in vitro activity of IMGN779 against FLT3-ITD AML cell lines and primary patient FLT3-ITD AML progenitor cells and LSCs and its high level of CD33-targeted in vivo activity in a FLT3-ITD AML xenograft model support the advancement of IMGN779 as a potential treatment for AML, including FLT3-ITD AML. Disclosures Whiteman: ImmunoGen, Inc.: Employment. Noordhuis:ImmunoGen, Inc.: Research Funding. Walker:ImmunoGen, Inc.: Employment. Watkins:ImmunoGen, Inc.: Employment. Kovtun:ImmunoGen, Inc.: Employment. Harvey:ImmunoGen, Inc.: Employment. Wilhelm:ImmunoGen, Inc.: Employment. Johnson:ImmunoGen, Inc.: Employment. Schuurhuis:ImmunoGen, Inc.: Research Funding. Ossenkoppele:ImmunoGen, Inc.: Research Funding. Lutz:ImmunoGen, Inc.: Employment, Equity Ownership.

Abstract: Infants with acute leukemia, especially neonates, comprise a unique high-risk population prone to chemotherapy resistance and treatment complications. Basal levels of expression of cell death and cell survival factors vary greatly in different types of cancer and are key determinants of response to treatment. Until now, expression of these factors had not been evaluated in detail in acute leukemia of infants. In this study the basal expression of pro-death and pro-survival genes in the intrinsic apoptosis pathway, apoptosis execution genes and mitochondrial maintenance genes was quantified in primary leukemia cells in a large cohort of infants, and relationships between gene expression and MLL status and clinical covariates were analyzed. Methods: Bone marrow or peripheral blood samples from the time of diagnosis were examined in 103 infants (age 1–363 d, median 177 d) with acute leukemia (63 ALL, 40 AML). White blood cell (WBC) counts ranged from 4.4–1676×103/μL (median 127.6×103/μL). MLL status was characterized by standard cytogenetics, FISH, Southern blot analysis, reverse transcriptase PCR and/or panhandle PCR approaches. The ALL cases were classified as MLL-AF4+ (n= 31), other MLL rearrangement positive (other MLL+) (n= 22) or MLL rearrangement negative (MLL−) (n= 10). Due to heterogeneity in partner genes, the AML cases were classified as MLL+ (n= 22) or MLL− (n= 18). Quantitative real time PCR analysis of total RNAs was performed using a custom TaqMan® low-density array with one or more assays, each in quadruplicate, for 35 cell death regulatory genes and 3 housekeeping genes, and ΔCT values (average cycle threshold values normalized to 18S rRNA) were computed. The Behrens-Fisher nonparametric multiple comparison test in the npmc package for R was used to determine the significance of the difference in median −ΔCT values among the three ALL groups and between the two AML groups (p & lt;0.001 considered as significant). Relationships were sought between −ΔCT values and clinical covariates (age, sex, WBC count, CNS status, events) by computing Spearman correlation coefficients and their levels of significance. Results: In ALL, expression of the following genes was greater in MLL-AF4+ than MLL− cases: anti-apoptotic BCL-2 and MCL-1; pro-apoptotic BAX and BID; apoptosis execution APAF1, CASP3 and CASP9; and mitochondrial maintenance COX5A, CYC1, UQCR1 and UQCR. For some of these genes, expression was also greater in other MLL+ than MLL− cases. In AML, expression of pro-apoptotic BAK and BIK was higher in MLL+ than MLL− cases. For the sample set as a whole, expression of the following genes was positively correlated with WBC count (r & gt;0.3; p & lt;0.01): anti-apoptotic BCL-2 and BCL-W; pro-apoptotic NOXA; apoptosis execution CASP8; and mitochondrial maintenance HCCS. The correlation between WBC count and BCL-2 was the strongest (r=0.40;p=4E-5). Only the expression of pro-apoptotic BIM was correlated with age at diagnosis and the correlation was not particularly strong (r = −0.246;p=0.01). Conclusions: These results suggest that infant ALL and AML differ with respect to the expression of genes that regulate cell death. Furthermore, cell death regulatory gene expression is affected more by MLL translocations in infant ALL than infant AML. This finding may explain the greater impact of MLL translocations on prognosis in infant ALL than AML. The abundance of specific pro- as well as anti-apoptotic BCL-2 family mRNAs in MLL+ infant ALL is also relevant to the identification of novel therapeutic targets in this pathway. The positive correlation between anti-apoptotic BCL-2 expression and WBC count is biologically plausible and consistent with the aggressive nature of acute leukemia in infants.

Abstract: Apoptosis is an essential process in embryonic tissue remodeling and adult tissue homeostasis. Within the adult hematopoietic system, it allows for tight regulation of hematopoietic cell subsets. Previously, it was shown that B-cell leukemia 2 (Bcl-2) overexpression in the adult increases the viability and activity of hematopoietic cells under normal and/or stressful conditions. However, a role for apoptosis in the embryonic hematopoietic system has not yet been established. Since the first hematopoietic stem cells (HSCs) are generated within the aortagonad-mesonephros (AGM; an actively remodeling tissue) region beginning at embryonic day 10.5, we examined this tissue for expression of apoptosis-related genes and ongoing apoptosis. Here, we show expression of several proapoptotic and antiapoptotic genes in the AGM. We also generated transgenic mice overexpressing Bcl-2 under the control of the transcriptional regulatory elements of the HSC marker stem cell antigen-1 (Sca-1), to test for the role of cell survival in the regulation of AGM HSCs. We provide evidence for increased numbers and viability of Sca-1+ cells in the AGM and subdissected midgestation aortas, the site where HSCs are localized. Most important, our in vivo transplantation data show that Bcl-2 overexpression increases AGM and fetal liver HSC activity, strongly suggesting that apoptosis plays a role in HSC development.

Abstract: The aorta-gonads-mesonephros (AGM) region autonomously generates the first adult repopulating hematopoietic stem cells (HSCs) in the mouse embryo. HSC activity is initially localized to the dorsal aorta and mesenchyme (AM) and vitelline and umbilical arteries. Thereafter, HSC activity is found in the urogenital ridges (UGs), yolk sac, and liver. As increasing numbers of HSCs are generated, it is thought that these sites provide supportive microenvironments in which HSCs are harbored until the bone marrow microenvironment is established. However, little is known about the supportive cells within these midgestational sites, and particularly which microenvironment is most supportive for HSC growth and maintenance. Thus, to better understand the cells and molecules involved in hematopoietic support in the midgestation embryo, more than 100 stromal cell lines and clones were established from these sites. Numerous stromal clones were found to maintain hematopoietic progenitors and HSCs to a similar degree as, or better than, previously described murine stromal lines. Both the AM and UG subregions of the AGM produced many supportive clones, with the most highly HSC-supportive clone being derived from the UGs. Interestingly, the liver at this stage yielded only few supportive stromal clones. These results strongly suggest that during midgestation, not only the AM but also the UG subregion provides a potent microenvironment for growth and maintenance of the first HSCs.

Abstract: Introduction: Although recent studies have refined the classification of B-progenitor and T-lineage acute lymphoblastic leukemia into gene-expression based subgroups, a comprehensive integration of significantly mutated genes and pathways for each subgroup is needed to understand disease etiology. Methods: We studied 2789 children, adolescents and young adults (AYA) with newly diagnosed B-ALL (n=2,322 cases) or T-ALL (n=467) treated on Children's Oncology Group (n=1,872) and St. Jude Children's Research Hospital trials (n=917). The cohort comprised childhood NCI standard-risk (41.8%; age range 1-9.99 yrs, WBC ≤ 50,000/ml), childhood NCI high-risk (44.5%; age range ≥10 to 15.99 yrs) and AYA (9.9%; age range 16-30.7 yrs). Genomic analysis was performed on tumor and matched-remission samples using whole transcriptome sequencing (RNA-seq; tumor only; n=1,922), whole exome sequencing (n=1,659), whole genome sequencing (n=757), and single nucleotide polymorphism array (n=1,909). Results: For B-ALL, 2104 cases (90.6%) were classified into 26 subgroups based on RNA-seq gene expression data and aneuploidy or other gross chromosomal abnormalities (iAMP21, Down syndrome, dicentric), deregulation of known transcription factors by rearrangement or mutation (PAX5 P80R, IKZF1 N159Y), or activation of kinase alterations (Ph+, Ph-like). For T-ALL, cases were classified into 9 previously described subtypes based on dysregulation of transcription factor genes and gene expression. In 1,659 cases subject to exome sequencing (1259 B-ALL, 405 T-ALL) we identified 18,954 nonsynonymous single nucleotide variants (SNV) and 2,329 insertion-deletion mutations (indels) in 8,985 genes. Overall, 161 potential driver genes were identified by the mutation-significance detection tool MutSigCV or by presence of pathogenic variants in known cancer genes. Integration of sequence mutations and DNA copy number alteration data in B-ALL identified 7 recurrently mutated pathways: transcriptional regulation (40.6%), cell cycle and tumor suppression (38.0%), B-cell development (34.5%), epigenetic regulation (24.7%), Ras signaling (33.0%), JAK-STAT signaling (12.0%) and protein modification (ubiquitination or SUMOylation, 5.0%). The top 10 genes altered by deletion or mutation in B-ALL were CDKN2A/B (30.1%), ETV6 (27.0%), PAX5 (24.6%), CDKN1B (20.3%), IKZF1 (17.6%), KRAS (16.5%), NRAS (14.6%), BTG1 (7.5%) histone genes on chromosome 6 (6.9%) and FLT3 (6.1%), and for T-ALL, CDKN2A/B (74.7%), NOTCH1 (68.2%), FBXW7 (21.3%), PTEN (20.5%) and PHF6 (18.2%) (Figure 1A). We identified 17 putative novel driver genes involved in ubiquitination (UBE2D3, UBE2A, UHRF1, and USP1), SUMOylation (SAE1, UBE2I), transcriptional regulation (ZMYM2, HMGB1), immune function (B2M), migration (CXCR4), epigenetic regulation (DOT1L) and mitochondrial function (LETM1). We also observed variation in the frequency of genes and pathways altered across B-ALL subtypes (Figure 1B). Interestingly, alteration of SAE1 and UBA2, novel genes that form a heterodimeric complex important for SUMOylation, and UHRF1 were enriched in ETV6-RUNX1 cases. Deletions of LETM1, ZMYM2 and CHD4 were associated with near haploid and low hypodiploid cases. Deletion of histone genes on chromosome 6 and alterations of HDAC7 were enriched in Ph+ and Ph-like ALL. Mutations in the RNA-binding protein ZFP36L2 were observed in PAX5alt, DUX4 and MEF2D subgroups. Genomic subtypes were prognostic. ETV6-RUNX1, hyperdiploid, DUX4 and ZNF384 ALL were associated with good outcome (5-yr EFS 91.1%, 87.2%, 91.9% and 85.7%, respectively), ETV6-RUNX1-like, iAMP21, low hyperdiploid, PAX5 P80R and PAX5alt were associated with intermediate outcome (5-yr EFS 68.6%, 72.2%, 70.8%, 77.0% and 70.9%, respectively), whilst KMT2A, MEF2D, Ph-like CRLF2 and Ph-like other conferred a poor prognosis (55.5%, 67.1%, 51.5% and 62.1%, respectively). TCF3-HLF and near haploid had the worst outcome with 5-yr EFS rates of 27.3% and 47.2%, respectively. Conclusions: These findings provide a comprehensive landscape of genomic alterations in childhood ALL. The associations of mutations with ALL subtypes highlights the need for specific patterns of cooperating mutations in the development of leukemia, which may help identify vulnerabilities for therapy intervention. Disclosures Gastier-Foster: Bristol Myers Squibb (BMS): Other: Commercial Research; Incyte Corporation: Other: Commercial Research. Willman:to come: Patents & Royalties; to come: Membership on an entity's Board of Directors or advisory committees; to come: Research Funding. Raetz:Pfizer: Research Funding. Borowitz:Beckman Coulter: Honoraria. Zweidler-McKay:ImmunoGen: Employment. Angiolillo:Servier Pharmaceuticals: Consultancy. Relling:Servier Pharmaceuticals: Research Funding. Hunger:Jazz: Honoraria; Amgen: Consultancy, Equity Ownership; Bristol Myers Squibb: Consultancy; Novartis: Consultancy. Loh:Medisix Therapeutics, Inc.: Membership on an entity's Board of Directors or advisory committees. Mullighan:Amgen: Honoraria, Other: speaker, sponsored travel; Loxo Oncology: Research Funding; AbbVie: Research Funding; Pfizer: Honoraria, Other: speaker, sponsored travel, Research Funding; Illumina: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: sponsored travel.

Abstract: Abstract 2801 Background: MLN4924 is an investigational inhibitor of Nedd8-activating enzyme (NAE), which plays an essential role in regulating the activity of the cullin-RING E3 ligases (CRLs). NAE controls the neddylation cascade that results in Nedd8 conjugation to the CRLs, which is required for ligase activity. NAE inhibition thus inhibits ubiquitination and proteasomal degradation of CRL substrates, which include proteins involved in cell-cycle regulation (p27), signal transduction (pIκBα), DNA replication (Cdt-1), stress response (Nrf-2), and other processes important to tumor cell growth and survival. In lymphoma cells, NAE inhibition with MLN4924 has been shown to result in apoptosis either through increased Cdt-1 levels, S-phase accumulation, and DNA re-replication, or via pIκBα stabilization and consequent NF-κB pathway inhibition. In vivo, MLN4924 treatment resulted in tumor growth inhibition and regressions in lymphoma xenograft models. This phase 1 dose-escalation study is the first investigation of MLN4924 in multiple myeloma (MM) and lymphoma patients. We have previously reported (Shah et al, ASH 2009) that the maximum tolerated dose (MTD) of MLN4924 on Schedule A of this study (days 1, 2, 8, and 9 of 21-day cycles) was 110 mg/m2, with dose-limiting toxicities (DLTs) including muscle cramps and febrile neutropenia. Analyses of peripheral blood mononuclear cells and skin biopsies indicated MLN4924 exerted the predicted pharmacodynamic (PD) effects in peripheral blood and skin, including inhibition of neddylated cullins and induction of pIκBα, Cdt-1, and Nrf-2. Two additional schedules of MLN4924 administration are now being investigated with the aim of increasing tolerability and the deliverable dose. Methods: Patients aged ≥18 years with ECOG performance status 0–2 and relapsed and/or refractory MM or lymphoma, including any B- or T-cell non-Hodgkin's lymphoma (NHL) and Hodgkin lymphoma (HL), following ≥2 prior lines of therapy were eligible. Primary objectives were to determine the MTD and safety profile of MLN4924 on the different dosing schedules, describe the pharmacokinetics (PK) and PD of MLN4924 in blood, and investigate PD effects in skin and tumor. Secondary objectives included evaluation of disease response. Patients received MLN4924 via a 60-minute intravenous infusion on either days 1, 4, 8, and 11 (Schedule B) or days 1 and 8 (Schedule C) of 21-day cycles for up to 12 months. Doses of 25–147 mg/m2 were investigated on Schedule A; for Schedules B and C, dose escalation started at the MTD of Schedule A, 110 mg/m2, and proceeded in 1.33-fold increments using a Bayesian continual reassessment method based on the occurrence of DLTs in cycle 1. The MTD was defined as the dose level closest to that predicted to result in a DLT rate of 25%. Adverse events (AEs) were graded using National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: To date, 7 patients (5 male, median age 60 years [range 48–68]) have been enrolled to Schedule B, 2 each at 110, 147, and 196, and 1 at 261 mg/m2; 2 have MM and 5 lymphoma (2 diffuse large B-cell lymphoma [DLBCL] , 1 small lymphocytic lymphoma, 1 mantle cell lymphoma [MCL], 1 nodular sclerosis HL). Patients have received a median of 3 cycles (range 2–5) to date. A total of 7 patients (all male, median age 49 years [range 45–66] ) have been enrolled to Schedule C, 2 each at 110 and 147, and 3 at 196 mg/m2; 4 have MM and 3 lymphoma (1 follicular lymphoma [FL], 1 MCL, 1 nodular sclerosis HL). Median number of cycles received is 4 (range 1–7). No DLTs and no grade ≥3 AEs have been reported on either schedule to date. On Schedule B, only grade 1 dyspnea and myalgia (both n=2) have been reported in 〉 1 patient, with grade 1 diarrhea (n=3), constipation, fatigue, and nausea (each n=2) reported on Schedule C. PK data for the 110 mg/m2 cohorts of Schedules B and C are consistent with the lack of significant accumulation of MLN4924 in plasma shown on Schedule A. One patient with HL on Schedule A achieved a partial response; no responses have been reported to date on Schedules B and C though some heavily treated patients have demonstrated stable disease for 5 or more cycles (1 FL, 7 cycles; 1 DLBCL, 5 cycles; 1 MM, 5 cycles). Conclusion: Enrollment and dose escalation are proceeding on Schedules B and C (at doses above Schedule A MTD) to determine the MTD on each schedule; updated clinical data will be presented, together with data on the PK and PD of MLN4924, on these dosing schedules. Disclosures: Shah: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding. Off Label Use: Investigational agent in clinical development for the treatment of multiple myeloma and lymphoma. O'Connor:Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Smith:Millennium Pharmaceuticals, Inc.: Honoraria, Research Funding, Speakers Bureau. Orlowski:Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding. Mulligan:Millennium Pharmaceuticals: Employment. Smith:Millennium Pharmaceuticals, Inc.: Employment. Pickard:Millennium Pharmaceuticals, Inc.: Employment. Dezube:Millennium Pharmaceuticals: Employment, Equity Ownership. Lonial:Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract: Abstract 1854 Poster Board I-880 Background: MLN4924 is a first-in-class small molecule inhibitor of NEDD8-activating enzyme (NAE), an essential component of the NEDD8 conjugation pathway in the ubiquitin-proteasome system. Inhibition of NAE with MLN4924 prevents conjugation of NEDD8 to the Cullin Ring Ligases (CRLs). This subsequently prevents ubiquitination and proteasomal degradation of CRL substrates, which include proteins involved in cell cycle regulation (p27), signal transduction (pIκBá), DNA replication (Cdt-1), stress response (Nrf-2), and other processes important to tumor cell growth and survival. MLN4924 has demonstrated potent antitumor activity in vitro against multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) cell lines as well as in mouse xenograft models of NHL. This phase 1 dose-escalation study is the first investigation of MLN4924 in MM or NHL patients (pts). The primary objectives were to determine the maximum tolerated dose (MTD) and safety profile of MLN4924, describe the pharmacokinetics (PK) and pharmacodynamics (PD) in blood (inhibition of NEDD8-Cullin levels in peripheral blood mononuclear cells [PBMCs]; Nrf-2 target gene transcription in whole blood), and investigate PD effects in skin (Cdt-1, Nrf-2 accumulation). Methods: Pts aged ≥18 yrs with relapsed and/or refractory MM or NHL after ≥2 prior lines of therapy were eligible. Pts received escalating doses of MLN4924 by IV infusion on days 1, 2, 8, and 9 of 21-day cycles; once the MTD for this schedule was reached, MTDs for other schedules will be investigated. MTD determination was based on an adaptive approach using a Bayesian continual reassessment method, with the MTD defined as the dose level closest to that predicted to result in a dose-limiting toxicity (DLT) rate of 25%. DLT was defined as: grade 4 neutropenia or thrombocytopenia for 〉 7 days; grade 3 neutropenia with fever/infection or thrombocytopenia with bleeding; grade ≥3 non-hematologic toxicity except arthralgia/myalgia, brief fatigue, or fever without neutropenia; and grade ≥2 MLN4924-related toxicities requiring dose reduction/discontinuation. For PD analysis, PBMCs and whole blood were isolated at screening, baseline, and following MLN4924 administration; skin biopsies for Cdt-1 and Nrf-2 assays were performed at baseline and after the second dose. Results: Among 22 pts enrolled to date, median age was 65 years, 13 were male, 14 had MM, and 8 had NHL (4 FL, 1 MCL, 1 DLBCL, 1 B-cell CLL/SLL, 1 transformed CLL). All MM pts had received prior autologous SCT, and 13, 9, and 9 had prior bortezomib, lenalidomide, and thalidomide, respectively. Seven NHL pts had received prior autologous SCT, 1 had a prior allogeneic SCT, and 8 had prior rituximab. Pts received MLN4924 at 6 dose levels: 25 (n=3), 50 (n=2), 65 (n=3), 83 (n=2), 110 (n=9), and 147 mg/m2 (n=3). Of the 15 (68% of the 22 enrolled) pts who received all 4 scheduled doses or had a DLT in cycle 1 (DLT-evaluable pts), 4 experienced a DLT: 1 grade 4 febrile neutropenia at 65 mg/m2; 1 grade 3 liver function tests at 110 mg/m2, and 1 grade 4 muscle cramps and 1 grade 2 myalgia that was considered dose limiting at 147 mg/m2. Thus, the MTD for this schedule was determined to be 110 mg/m2. The most common adverse events (AEs, NCI CTCAE v3.0) included fatigue, nausea, myalgia, and elevated liver enzymes. With the exception of the grade 4 neutropenia seen at 65 mg/m2, myelosuppression was limited. No infusion-related reactions were noted. Elevated CRP levels appeared transient in most cases. There have been no treatment-related deaths; 1 MM pt died due to progressive disease. MLN4924 displayed a multiexponential PK profile with a half life of 4–9 hours, relatively low PK variability, and approximately dose-proportional increases in total plasma exposure over the 25–147 mg/m2 dose range. NEDD8-Cullin levels in PBMCs were inhibited and Nrf-2 target gene transcripts in whole blood were higher vs baseline after MLN4924 administration, indicative of NAE inhibition. Cdt-1 and Nrf-2 levels in skin increased above baseline following the second dose of MLN4924, indicative of NAE inhibition in peripheral tissue. The 110 mg/m2 dose level is being expanded to more fully characterize safety, PK, and PD in MM and NHL. Subsequent pts will be enrolled to receive MLN4924 on 2 other schedules. Conclusions: This early analysis provides evidence of PD inhibition of NAE activity by MLN4924 in blood and skin, and supports continued investigation of MLN4924. Disclosures: Shah: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Elan: Consultancy; Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Off Label Use: MLN4924 is not approved for the treatment of multiple myeloma or non-Hodgkin lymphoma.. Jakubowiak:Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Berger:Millennium Pharmaceuticals, Inc.: Employment. Mulligan:Millennium Pharmaceuticals, Inc.: Employment. Petruzzelli:Pfizer: Equity Ownership; Millennium Pharmaceuticals, Inc.: Employment; Amgen: Equity Ownership. Pickard:Millennium Pharmaceuticals, Inc.: Employment. Smith:Millennium Pharmaceuticals, Inc.: Employment. Venkatakrishnan:Millennium Pharmaceuticals, Inc.: Employment. Lonial:Novartis: Consultancy; Gloucester: Research Funding; BMS: Consultancy; Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding; Celgene: Consultancy.

Abstract: The efficacy of three therapeutic programs for acute leukemia were compared. These programs included (1) Methotrexate (Phase I) followed by 6-mercaptopurine (Phase II); (2) 6-mercaptopurine (Phase I) followed by Methotrexate (Phase II); and (3) Combination Therapy, i.e., 6-mercaptopurine given in combination with Methotrexate. In children with acute lymphocytic leukemia the remission rate was 59 per cent for combination therapy, 47 per cent for 6-mercaptopurine, and 29 per cent for Methotrexate. The better remission rate for combination therapy is consistent with that predicted if it is assumed that 6-mercaptopurine and Methotrexate act independently. The median duration of complete remissions for the three treatments was not different (4 to 5 months). However, long lasting remissions were more frequent in patients receiving combination therapy. The median survival from the onset of therapy to death was 9 months. There were no differences between the three treatment programs as regards survival. In adults the remission rate was 15 per cent for combination therapy, 21 per cent for 6-mercaptopurine and 7 per cent for Methotrexate. As regards survival in adults, early deaths were more common in patients who received MTX as initial therapy, whereas after 5 months survival was somewhat better in those patients receiving combination therapy. In both children and adults there was no evidence that prior treatment with one of the antimetabolites altered response to the other antimetabolite. This result differs from those in animal models, and its effect on our concept of the mechanism of resistance is discussed. Responsiveness to the second course of antimetabolite therapy (Phase II) was as good as that to the first course of treatment. This was true for the remission rate, remission duration, and even for survival when appropriate corrections were made. Thus, responsiveness to drug therapy is maintained as the disease progresses temporally. It may be concluded therefore that new agents can be effectively studied in patients with "late" disease. Responsiveness to Phase II therapy was independent of responsiveness to Phase I. The most common and severe toxic manifestations related to the bone marrow and gastrointestinal tract. There were no major differences quantitatively in the toxicity for the three treatment programs in children in spite of the fact that the drugs were given in full dosage in the combination program. Oral ulcers and a generalized erythematous rash occurred significantly more frequently in patients receiving Methotrexate. Jaundice was significantly more frequent in adults and in patients receiving 6-MP.

Abstract: Background: Viral vectors based on the Edmonston strain of measles virus (MV-Edm) selectively destroy all tumor cell lines tested in vitro. The oncolytic activity of the virus is enhanced by expression of the thyroidal sodium iodide symporter (MV-NIS) that allows selective 131I uptake by infected tumor cells and eliminates myeloma tumor xenografts that are resistant to the parent virus. MV-NIS is being considered for therapy of patients with relapsed or refractory multiple myeloma. Advanced myeloma is associated with significant immunosuppression with the potential risk of uncontrolled virus proliferation. The number of agents with activity against MV is limited. Low energy (Auger) electrons have a short path length and selectively damage cells in which the isotope decays. Thus, we hypothesized that the Auger electron emitting isotope 125I, selectively taken up by cells expressing NIS, can be used to control viral proliferation. Methods: A replication competent MV that expressed both a soluble form of carcinoembryonic antigen (CEA) and NIS (MV-NICE) was rescued and characterized. Cells were infected with MV-NICE or control vectors and exposed to 125I with appropriate controls. CEA expression and viral titers were determined at different time points. The role of free radical generation on virus replication was explored. In vivo control of MV-NICE replication with 125I was attempted. Results: MV-NICE replication in vitro is inhibited by the selective uptake of 125I by cells expressing NIS. Extracellular decay of the isotope has no effect on virus proliferation. Auger electron damage is in part mediated by free radicals and abrogated by glutathione. In myeloma xenografts, control of MV-NICE with 125I was not possible under the conditions of the experiment. Conclusion: MV-NICE does not replicate faster in the presence of radiation under our experimental conditions. Auger electron emitting isotopes effectively stop propagation of MV vectors expressing NIS in vitro. Additional work is necessary to translate these observations in vivo.