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NVP-AUY922 (AUY; Luminespib) with or without bortezomib showed preclinical activity against multiple myeloma (MM) cells. This phase 1/1B study assessed NVP-AUY922 alone and with bortezomib in patients with relapsed or refractory MM.Dose escalation was guided by an adaptive Bayesian logistic regression model. In phase 1, patients who progressed after 2 to 4 prior therapies received NVP-AUY922 intravenously once weekly. In phase 1B, patients who progressed after 2 or fewer prior therapies received NVP-AUY922 plus bortezomib. The primary objective was to determine the maximum tolerated dose (MTD) of NVP-AUY922.Twenty-four patients received NVP-AUY922 monotherapy at doses of 8 to 70 mg/m(2) . One dose-limiting toxicity (DLT) was observed (grade 3 blurred vision at 70 mg/m(2) ); no MTD was reached. The recommended phase 2 dose was 70 mg/m(2) . The most frequent drug-related adverse events (AEs) were diarrhea, nausea, and ocular toxicities. Grade 3/4 AEs were uncommon (10%). Eight patients discontinued treatment because of AEs; 5 had ocular toxicities (≥45 mg/m(2) ). The best response was stable disease in 66.7% of the patients. There were no partial or complete responses. Five patients received NVP-AUY922 (which was started at 50 mg/m(2) ) plus bortezomib (1.3 mg/m(2) ). Three of these patients experienced DLT. No further dose escalation was performed; the MTD for NVP-AUY922 plus bortezomib was not established.This study showed disease stabilization with NVP-AUY922 in patients with relapsed or refractory MM. The MTD for NVP-AUY922 was not reached, but reversible ocular toxicity has been reported at high dose levels. Bortezomib at the standard recommended dose plus NVP-AUY922 was not tolerated.

Mutation of p53 is a rare event in multiple myeloma, but it is unknown if p53 signaling is functional in myeloma cells, and if targeted nongenotoxic activation of the p53 pathway is sufficient to kill tumor cells. Here, we demonstrate that treatment of primary tumor samples with a small-molecule inhibitor of the p53–murine double minute 2 (MDM2) interaction increases the level of p53 and induces p53 targets and apoptotic cell death. Significantly, given the importance of the bone marrow microenvironment for the support and drug resistance of myeloma cells, tumor cells undergo effective apoptosis also in the presence of stromal cells, which themselves appear to tolerate exposure to nutlin-3. The in vitro toxicity of nutlin-3 was similar to that of the genotoxic drug melphalan. Because nutlin-mediated p53 activation is not dependent on DNA damage, MDM2 antagonists may help to avoid or reduce the severe genotoxic side effects of chemotherapeutic agents currently used to treat multiple myeloma. Therefore, MDM2 antagonists may offer a new treatment option for this disease.

Beta-catenin is upregulated in many human cancers and considered to be an oncogene. Hepatocellular carcinoma (HCC) is one of the most prevalent human malignancies, and individuals who are chronic hepatitis B virus (HBV) carriers have a greater than 100-fold increased relative risk of developing HCC. Here we report a mechanism by which HBV-X protein (HBX) upregulates beta-catenin. Erk, which is activated by HBX, associates with GSK-3beta through a docking motif ((291)FKFP) of GSK-3beta and phosphorylates GSK-3beta at the (43)Thr residue, which primes GSK-3beta for its subsequent phosphorylation at Ser9 by p90RSK, resulting in inactivation of GSK-3beta and upregulation of beta-catenin. This pathway is a general signal, as it was also observed in cell lines in which Erk-primed inactivation of GSK-3beta was regulated by IGF-1, TGF-beta, and receptor tyrosine kinase HER2, and is further supported by immunohistochemical staining in different human tumors, including cancers of the liver, breast, kidney, and stomach.

Certain bispecific antibodies exhibit an extraordinary potency and efficacy for target cell lysis by eliciting a polyclonal T-cell response. One example is a CD19-/CD3-bispecific single-chain antibody construct (bscCD19xCD3), which at femtomolar concentrations can redirect cytotoxic T cells to eliminate human B lymphocytes, B lymphoma cell lines and patient-derived malignant B cells. Here we have further explored the basis for this high potency. Using video-assisted microscopy, bscCD19xCD3 was found to alter the motility and activity of T cells from a scanning to a killing mode. Individual T cells could eliminate multiple target cells within a 9 hr time period, resulting in nuclear fragmentation and membrane blebbing of target cells. Complete target cell elimination was observed within 24 hr at effector-to-target cell ratios as low as 1:5. Under optimal conditions, cell killing started within minutes after addition of bscCD19xCD3, suggesting that the rate of serial killing was mostly determined by T-cell movement and target cell scanning and lysis. At all times, T cells remained highly motile, and no clusters of T and target cells were induced by the bispecific antibody. Bystanding target-negative cells were not detectably affected. Repeated target cell lysis by bscCD19xCD3-activated T cells increased the proportion of CD19/CD3 double-positive T cells, which was most likely a consequence of transfer of CD19 from B to T cells during cytolytic synapse formation. To our knowledge, this is the first study showing that a bispecific antibody can sustain multiple rounds of target cell lysis by T cells.

A recently developed bispecific antibody construct, directed against CD19 and CD3 (bscCD19xCD3), induces T-cell-mediated lysis of allogeneic and autologous B cells in a specific and highly efficient manner. Since knowledge of the molecular mechanisms underlying this lysis is limited, a study on bscCD19xCD3-activated T-cell-effector pathways was performed. BscCD19xCD3-induced lysis of target B-cell lines Nalm-6, Daudi, and Raji and of autologous primary B cells is caused by the perforin-dependent granule-exocytosis pathway but not by the death ligands FasL, TRAIL, or TNF-alpha. When activated by bscCD19xCD3 and Raji cells, T cells express FasL mRNA, but incubation of Raji cells with cell-free supernatants from cytotoxicity experiments caused an upregulation of c-Flipl, possibly accounting for the cells' insensitivity toward death-receptor-mediated lysis. In addition to granule exocytosis, Raji cells are lysed by at least one mechanism independent of perforin, which requires transport through the T cell's Golgi apparatus.

Notch receptors expressed on hematopoietic stem cells interact with their ligands on bone marrow stromal cells and thereby control cell fate decisions and survival. We recently demonstrated that Notch signaling is involved in proliferation and survival of B cell-derived tumor cells of classic Hodgkin disease and described a novel mechanism for the oncogenic capacity of Notch. In this study we investigated whether Notch signaling is involved in the tight interactions between neoplastic plasma cells and their bone marrow microenvironment, which are essential for tumor cell growth in multiple myeloma (MM). Here we demonstrate that Notch receptors and their ligand Jagged1 are highly expressed in cultured and primary MM cells, whereas nonneoplastic counterparts show low to undetectable levels of Notch. Functional data indicate that ligand-induced Notch signaling is a growth factor for MM cells and suggest that these interactions contribute to myelomagenesis in vivo. (Blood. 2004;103:3511-3515)

Persistence or recurrence of minimal residual disease (MRD) after chemotherapy results in clinical relapse in patients with acute lymphoblastic leukemia (ALL). In a phase 2 trial of B-lineage ALL patients with persistent or relapsed MRD, a T cell–engaging bispecific Ab construct induced an 80% MRD response rate. In the present study, we show that after a median follow-up of 33 months, the hematologic relapse-free survival of the entire evaluable study cohort of 20 patients was 61% (Kaplan-Meier estimate). The hema-tologic relapse-free survival rate of a subgroup of 9 patients who received allogeneic hematopoietic stem cell transplantation after blinatumomab treatment was 65% (Kaplan-Meier estimate). Of the subgroup of 6 Philadelphia chromosome–negative MRD responders with no further therapy after blinatumomab, 4 are in ongoing hematologic and molecular remission. We conclude that blinatumomab can induce long-lasting complete remission in B-lineage ALL patients with persistent or recurrent MRD. The original study and this follow-up study are registered at www.clinicaltrials.gov as NCT00198991 and NCT00198978, respectively.

Recently, it has been demonstrated that macrophage inflammatory protein 1- alpha (MIP-1 alpha) is crucially involved in the development of osteolytic bone lesions in multiple myeloma (MM). The current study was designed to determine the direct effects of MIP-1 alpha on MM cells. Thus, we were able to demonstrate that MIP-1 alpha acts as a potent growth, survival, and chemotactic factor in MM cells. MIP-1 alpha-induced signaling involved activation of the AKT/protein kinase B (PKB) and the mitogen-activated protein kinase (MAPK) pathway. In addition, inhibition of AKT activation by phosphatidylinositol 3- kinase (PI3-K) inhibitors did not influence MAPK activation, suggesting that there is no cross talk between MIP-1 alpha-dependent activation of the PI3-K/AKT and extracellular-regulated kinase (ERK) pathway. Our data suggest that besides its role in development of osteolytic bone destruction, MIP-1 alpha also directly affects cell signaling pathways mediating growth, survival, and migration in MM cells and provide evidence that MIP-1 alpha might play a pivotal role in the pathogenesis of MM.

We have recently demonstrated that a recombinant single-chain bispecific Ab construct, bscCD19xCD3, in vitro induces rapid B lymphoma-directed cytotoxicity at picomolar concentrations with unstimulated peripheral T cells. In this study, we show that treatment of nonobese diabetic SCID mice with submicrogram doses of bscCD19xCD3 could prevent growth of s.c. human B lymphoma xenografts and essentially cured animals when given at an early tumor stage. The effect was dose dependent, dependent on E:T ratio and the time between tumor inoculation and administration of bscCD19xCD3. No therapeutic effect was seen in the presence of human lymphocytes alone, a vehicle control, or with a bispecific single-chain construct of identical T cell-binding activity but different target specificity. In a leukemic nonobese diabetic SCID mouse model, treatment with bscCD19xCD3 prolonged survival of mice in a dose-dependent fashion. The human lymphocytes used as effector cells in both animal models did not express detectable T cell activation markers at the time of coinoculation with tumor cells. The bispecific Ab therefore showed an in vivo activity comparable to that observed in cell culture with respect to high potency and T cell costimulus independence. These properties make bscCD19xCD3 superior to previously investigated CD19 bispecific Ab-based therapies.

The interleukin 6/glycoprotein 130/signal transducer and activator of transcription 3 (IL-6/gp130/STAT3) pathway has been reported to play an important role in the pathogenesis of multiple myeloma (MM) and for survival of MM cells. However, most data concerning the role of IL-6 and IL-6–triggered signaling pathways were obtained from experiments performed with MM cell lines and without considering the bone marrow microenvironment. Thus, the precise role of IL-6 and its intracellular signaling pathways for survival of human MM cells is still unclear. Here we show that treatment of human MM cells (IL-6–dependent MM cell line INA-6 and primary MM cells) with the IL-6 receptor antagonist Sant7 or with an anti-gp130 monoclonal antibody (mAb) induced apoptosis if the cells were cultured in the absence of bone marrow stromal cells (BMSCs). In contrast, apoptosis could not be observed if the MM cells were cocultured with BMSCs. The analysis of intracellular pathways revealed that Sant7 and anti-gp130 mAb were effectively inhibiting the phosphorylation of gp130 and STAT3 in the absence and presence of BMSCs, whereas ERK1 and ERK2 (ERK1,2) phosphorylation was only slightly affected. In contrast, treatment with the farnesyl transferase inhibitor, FPT III, induced apoptosis in MM cells in the absence or presence of BMSCs and led to a complete inhibition of the Ras/mitogen-activated protein kinase pathway. These observations indicate that the IL-6/gp130/STAT3 pathway is not essential for survival of human myeloma cells if they are grown in the presence of cells from the bone marrow microenvironment. Furthermore, we provide evidence that farnesyl transferase inhibitors might be useful for the development of novel therapeutic strategies for the treatment of MM.

Acute graft-versus-host disease is still a major cause of transplant-related mortality after allogeneic stem cell transplantation. It requires immunosuppressive treatments that broadly abrogate T cell responses, including beneficial ones directed against tumor cells or infective pathogens. Inhibition of the heat shock protein of 90 kDa has been demonstrated to eliminate tumor cells, as well as alloreactive T cells while preserving antiviral T cell immunity. Here, we show that the suppressive effects of heat shock protein of 90 kDa inhibition on alloreactive T cells were synergistically enhanced by concomitant inhibition of the PI3K/Akt signaling pathway, which is also strongly activated upon allogeneic stimulation. Molecular analyses revealed that this antiproliferative effect was mainly mediated by induction of cell-cycle arrest and apoptosis. In addition, we observed an increased proportion of activated regulatory T cells, which critically contribute to acute graft-versus-host disease control, upon combined heat shock protein of 90 kDa/Akt isoforms 1 and 2 or heat shock protein of 90 kDa/PI3K/p110δ isoform inhibition. Moreover, antiviral T cell immunity was functionally preserved after combined heat shock protein of 90 kDa/Akt isoforms 1 and 2 inhibition. Taken together, our data suggest that the combined heat shock protein of 90 kDa/PI3K/Akt inhibition approach represents a reasonable dual strategy to suppress residual tumor growth and efficiently deplete alloreactive T cells and thus, provide a rationale to prevent and treat acute graft-versus-host disease selectively without impairing pathogen-specific T cell immunity.

Constitutive phosphatidylinositide 3-kinase (PI3K) signalling has been implicated in multiple myeloma (MM) pathophysiology and is regarded as an actionable target for pharmacological intervention. Isoform-specific PI3K inhibition may offer the most focused treatment approach and could result in greater clinical efficacy and reduced side effects. We therefore performed isoform-specific knockdown of PIK3CA, PIK3CB, PIK3CD, and PIK3CG to analyse their individual contributions to MM cell survival and downstream signalling. In addition, we tested the effectivity of the novel PI3K isoform-specific inhibitors BYL-719 (PIK3CA), TGX-221 (PIK3CB), CAL-101 (PIK3CD), and CAY10505 (PIK3CG). We found the PIK3CA isoform to be of paramount importance for constitutive Akt activity in MM cells, and - in contrast to inhibition of other class I isoforms - only the blockade of PIK3CA was sufficient to induce cell death in a sizeable subgroup of MM samples. Furthermore, pharmacological PIK3CA inhibition in combination treatments of BYL-719 and established anti-myeloma agents resulted in strongly enhanced MM cell death. Our data thus clearly indicate therapeutic potential of PIK3CA inhibitors and support their clinical evaluation in multiple myeloma.

Cell lines represent the everyday workhorses for in vitro research on multiple myeloma (MM) and are regularly employed in all aspects of molecular and pharmacological investigations. Although loss-of-function studies using RNA interference in MM cell lines depend on successful knockdown, no well-established and widely applied protocol for efficient transient transfection has so far emerged. Here, we provide an appraisal of electroporation as a means to introduce either short-hairpin RNA expression vectors or synthesised siRNAs into MM cells. We found that electroporation using siRNAs was much more efficient than previously anticipated on the basis of transfection efficiencies deduced from EGFP-expression off protein expression vectors. Such knowledge can even confidently be exploited in "hard-to-transfect" MM cell lines to generate large numbers of transient knockdown phenotype MM cells. In addition, special attention was given to developing a protocol that provides easy implementation, good reproducibility and manageable experimental costs.

Introduction: Proteasome inhibition is the backbone of various Multiple Myeloma (MM) treatment regimens, leading to durable responses and high quality remissions. However, under prolonged therapy patients eventually develop drug resistance and the underlying mechanisms have been poorly understood. Proteasome inhibitor resistant cell lines were generated by continuous exposure to proteasome inhibiting drugs. In these cell line models a number of variants within the PSMB5 gene were observed. This includes single point mutations, leading to conformational changes of the _5 subunit within the 20S proteolytic core of the proteasome, impairing its chymotryptic catalytic function and the binding of inhibitory drugs. However, no PSMB5 mutations could, so far, be identified in human disease, leaving the functional relevance of such mutations to be determined. Methods: We applied the MM Mutation Panel (M3P) and used the Personal Genome Machine (Life Technologies) to sequence CD138+ purified bone marrow plasma cells and peripheral blood germ line control from a MM patient in third relapse that had been previously treated by various proteasome inhibitor containing therapies (VTD-PACE, VCD, PAD-Rev). This patient was subsequently treated with a pomalidomide, bortezomib, adriamycin and dexamethasone combination therapy (Pom-PAD) and achieved a partial remission after 4 cycles of therapy. When being exposed to VCD at earlier relapse a complete remission was induced within 6 cycles of therapy, demonstrating excellent response to proteasome inhibition at this earlier disease stage. Results: We identified clonal missense mutations in this patient at known NRAS hotspot location (p.Gln61Arg) and in MAX (p.Arg35His). Most notably we found and validated four subclonal single point mutations in PSMB5, each of them in subclonal frequencies with variant reads (VR) ranging from 1.9%- 5.9% (average read depth 750X). All PSMB5 mutations occurred in a highly conserved region in exon 2 of the gene (p.Cys122Tyr, p.Met104Ile, p.Ala86Pro, p.Ala79Thr), with three of them being located within the proteasome inhibitor drug binding site. Our 400bp amplicon design allowed us to observe that each mutation identified in PSMB5 is exclusively present on a different sequencing read and no reads are shared between the mutations. This implies that the mutations are present on different subclones of the tumor, which means that, despite low VR frequencies of the single mutation, in sum more than a quarter of the whole tumor might be affected by mutated PSMB5. At a disease stage when the patient was well responsive to proteasome inhibitor treatment (at diagnosis and at first relapse), of note, none of the mutations in PSMB5 is detectable. Conclusion: Here we report the first in human PSMB5 mutation in a MM patient. These mutations evolved in parallel within different subclones of the disease under the selective pressure of bortezomib- containing treatment regimens, representing branching evolution. It is to speculate whether previous investigations negating the existence of PSMB5 mutations in proteasome inhibitor treated patients might not have sequenced deep enough or did set up a sensitivity cut-off too rigid to detect such subclonal mutations. Our finding suggests that the mutations identified may contribute to the development of proteasome inhibitor resistance, emphasizing the need for more detailed genomic characterization of tumors, including minor subclonal mutation detection. Functional analysis of the mutations is ongoing and results will be presented at the meeting. Figure Figure. Disclosures No relevant conflicts of interest to declare.

Introduction: Blinatumomab (blin), a CD19/CD3 bispecific T-cell engager (BiTE®) antibody construct, has shown clinical efficacy in patients with both B-precursor acute lymphoblastic leukemia (ALL) and B-cell non-Hodgkin lymphoma (NHL). NEs are known blin-associated adverse drug reactions; most NEs occur early during the first treatment cycle and are transient and fully reversible. While NEs are manageable in ALL (favorable risk/benefit profile at a maximum target dose of 28 µg/day), NEs increase in frequency and were dose-limiting in low-grade NHL. The maximum tolerated dose in NHL was 112 µg/day. Here we present translational and single-patient data for potential mitigation strategies for blin-associated NEs. Methods: Pharmacokinetic and pharmacodynamic data from blin clinical studies in NHL and ALL were combined to develop a pathogenetic model for blin-associated NEs. The mitigation potential of substances with antiadhesive properties was studied in vitro in a flow chamber system mimicking blin-induced T-cell redistribution. Three patients with low-grade NHL who had a higher risk of developing NEs due to their low peripheral blood B/T-cell ratios received concomitant pentosan polysulfate (PPS) at infusion start and dose step. ClinicalTrials.gov NCT00274742, NCT00560794, NCT01209286, NCT01471782. Results: T-cell redistribution occurred at infusion start and dose step of blin irrespective of circulating B cells. Concurrently, T cells upregulated the activation marker CD69 and the T-cell adhesion molecule LFA-1 switched from its low to intermediate affinity isoform as shown by binding of soluble ICAM-1. Blood vessel endothelial cells were activated as indicated by release of angiopoietin-2 and clinical signs of peripheral edema. Monocyte and thrombocyte redistribution were also observed. Both B and T cells were detected in cerebrospinal fluid (CSF) of some patients with NEs, and quantifiable blin concentrations were measured in CSF of some patients independent of blood-CSF barrier integrity. A low B/T-cell ratio in peripheral blood (NHL) and/or bone marrow (ALL) has been identified as a potential risk factor for developing NEs. In flow chamber experiments, addition of blin mimicked T-cell redistribution as indicated by reduced T-cell rolling velocity and increased T-cell adhesion to brain microvascular endothelial cells and by upregulation of P-selectin and ICAM-1 adhesion molecules on endothelial cells. Substances potentially interfering with interactions between T cells and endothelial cells (eg, PPS, minocycline) reversed the above-described effects to levels seen without the addition of blin. T-cell kinetics of three patients receiving concomitant PPS at infusion start and dose step showed delayed T-cell redistribution (without circulating B cells) compared with patients without PPS coadministration. These altered T-cell kinetics correlated with less severe NEs; no treatment interruptions or discontinuations were necessary. Finite PPS coadministration had no apparent negative impact on clinical response as two patients achieved an objective response, including one patient who has been in ongoing remission for more than six years. Conclusion: We propose an evidence-based model for the development of blin-associated NEs: 1) First exposure to blin or dose steps increase endothelial adhesiveness of circulating T cells. 2) Adhering T cells activate the endothelium and start extravasating; activated endothelium attracts other circulating leukocytes. 3) At low B/T-cell ratios, extravasated T cells first encountering (rare) B cells in the brain are activated by blin in the perivascular space to locally secret cytokines and chemokines that induce transient neuroinflammation including transmigration of monocytes. 4) Attracted non-T cells and other released factors enhance transient neurotoxicity. Based on this model, T-cell adhesion to blood vessel endothelial cells is the first necessary (but not sufficient) step in the pathogenesis of blin-associated NEs. Coadministration of substances with antiadhesive properties at infusion start and dose steps may offer opportunities to mitigate blin-associated NEs to further improve the safety and efficacy of blin therapy. Disclosures Klinger: Amgen Research (Munich) GmbH: Employment, Equity Ownership, Patents & Royalties: Blinatumomab. Zugmaier:Amgen: Employment, Patents & Royalties. Naegele:Amgen Research (Munich) GmbH: Employment, Equity Ownership, Patents & Royalties. Goebeler:GEmoAb: Consultancy; Novartis: Consultancy; Roche: Consultancy. Brandl:Amgen: Employment. Kufer:AMGEN Research Munich: Employment, Equity Ownership, Patents & Royalties.

PO-001 Targeted sequencing of relapsed/ refractory myeloma patients identifies an enrichment of mutations in MAPK and Cereblon pathways K.M. Kortum, E.K. Mai, N.H. Hanafiah, S. Barrio, L. Bruins, M. Merz, J. Xu, K. Pashayeva, Y.X. Zhu, C.X. Shi, P. Jedlowski, G. Ahmann, M. Andrulis, J. Hillengass, H. Goldschmidt, R. Fonseca, P.L. Bergsagel, E. Braggio, M.S. Raab, A.K. Stewart Department of Hematology, Mayo Clinic in Arizona, USA; Department of Internal Medicine V, Heidelberg University Hospital, Germany; Institute of Pathology, Heidelberg University Hospital, Germany; National Center of Tumor Diseases (NCT), Germany; German Cancer Research Center (DKFZ)

Activation of T cells was shown to up-regulate the Fas ligand (FasL) which binds to the CD95 (APO-1/Fas) antigen and mediates activation-induced cell death (AICD) of activated T cells and T lymphoma cells. A recent report showed that mouse B cells express the FasL upon activation with lipopolysaccharide (LPS). We therefore asked whether activation of human B cells induces expression of FasL and whether AICD is mediated, as in T cells, through autocrine production of the FasL. We used human tonsillar B cells and Burkitt lymphoma cell lines which were activated by CD40 ligand, surface (s)IgM cross-linking, or LPS. Northern and Western blot analysis failed to detect FasL during B cell activation or AICD of both normal and malignant B cells. Low-level expression of FasL was detected by reverse transcriptase-polymerase chain reaction. Functional experiments, however, showed that FasL is not functionally expressed upon activation. IgM-mediated AICD in the tonsillar or Burkitt lymphoma B cells could not be inhibited by FasL blocking. Thus, our data show that, in contrast to T cells, activation of normal or malignant human B cells does not lead to functional FasL expression.

We studied the efficiency of indirect tumor cell purging via enrichment of CD34+ hematopoietic progenitor cells from leukapheresis products (LP) in breast cancer patients based on immunomagnetic selection of CD34+ cells. Detection of tumor cells was made by immunocytochemical staining. In addition, we evaluated the capacity of cytokeratin 19 (CK19)- and a novel epidermal growth factor receptor (EGF-R)-specific reverse transcriptase–polymerase chain reaction (RT-PCR) for monitoring tumor cell depletion. LP from 13 breast cancer patients were analyzed. Twenty-three CD34 selection procedures were performed. A median of 1.4 × 1010 total nucleated cells ([TNC] range, 0.88 to 3.5 × 1010) with a median CD34 purity of 2.5% (range, 0.4% to 6.3%) were entered into the selection procedure. Immunomagnetic CD34 enrichment resulted in a median purity of 83.3% (range, 45% to 95.4%) and a median recovery of 73.2% (range, 22% to 95%). Retransfusion of CD34-selected cells after high-dose chemotherapy resulted in a rapid and sustained hematologic recovery, reaching an absolute neutrophil count of 500/μL at day +10 and platelet count of 20,000/μL at day +11. Tumor cell depletion was quantified by immunocytochemical detection of CK19-positive cells. By this method, a median tumor cell depletion of 1.9 log (range, 0.7 to

Resistance to apoptosis plays an important role in malignancies that are refractory to chemotherapy treatment. Recently we have shown that the expression of bax-alpha, a death-promoting member of the bcl-2 family, is down-regulated in breast cancer and have provided evidence that low bax expression might contribute to the pathogenesis of breast cancer. In this study we were able to demonstrate the role of this gene in chemotherapy-induced apoptosis. We transfected bax-alpha into the breast-cancer cell lines R30C and MCF-7 under the control of an inducible tetracycline-dependent expression system. Induction of bax-alpha expression did not affect viability by itself but strongly increased chemosensitivity to epirubicin. We were able to demonstrate that this sensitization is due to apoptosis. These data might explain the recently published observation that reduced expression of bax is associated with poor response rates to chemotherapy in breast cancer.

There is a considerable lack of understanding about the common molecular defects that form the basis for the occurrence of Hodgkin's lymphoma. Despite a number of molecular tools used thus far in immunophenotypic and karyotypic studies, it has not been possible to establish a single common trait among various Hodgkin (H)-cell lines or primary tumor cells that would allow classification into a particular hematopoietic lineage. With this study, we demonstrate that a characteristic expression pattern of transcription factors provides a unifying principle. Seven different cell lines derived from patients with Hodgkin's disease (HD), as well as primary H/Reed-Sternberg (RS) cells isolated from the pericardial fluid of a patient with HD, were compared with a number of hematopoietic and nonhematopoietic cell lines for the expression of Oct-2, a tissue-specific transcription factor normally restricted to B cells, and nuclear factor kappa B (NF-kappa B), an inducible transcription factor. Regardless of the heterogeneous phenotypes and genotypes of the H cell lines, which varied inconsistently between B-cell-, T-cell-, or monocyte-like properties, all H cells tested displayed expression of Oct-2 protein at levels comparable to those seen in B cells. Furthermore, all cell lines showed an abundant constitutive nuclear NF-kappa B activity. Interestingly, anaplastic large-cell lymphoma (ALCL) cell lines, which have many features in common with H/RS cells, were devoid constitutive nuclear NF- kappa B activity. Unlike the constitutive NF-kappa B activity known for B cells, which mainly consists of the p50 and c-Rel or RelB subunits, we demonstrate by antibody supershifting experiments that H cells contain constitutive nuclear p50 and p65, the dimeric NF-kappa B normally observed only for limited time intervals after stimulation with diverse inducers. Additionally, some H-cell lines also displayed nuclear c-Rel activity, whereas RelB or p52 were not detected as part of the constitutive activity. The expression pattern of Oct-2 and NF- kappa B appears to be a unifying and characteristic property of H cells and might explain the deregulated expression of various cytokines leading to the clinical and pathologic manifestations of HD.

Despite therapeutic advances multiple myeloma remains largely incurable, and novel therapeutic concepts are needed. The Hsp90-chaperone is a reasonable therapeutic target, because it maintains oncogenic signaling of multiple deregulated pathways. However, in contrast to promising preclinical results, only limited clinical efficacy has been achieved through pharmacological Hsp90 inhibition. Because Hsp70 has been described to interact functionally with the Hsp90-complex, we analyzed the suitability of Hsp72 and Hsp73 as potential additional target sites. Expression of Hsp72 and Hsp73 in myeloma cells was analyzed by immunohistochemical staining and western blotting. Short interfering RNA-mediated knockdown or pharmacological inhibition of Hsp72 and Hsp73 was performed to evaluate the role of these proteins in myeloma cell survival and for Hsp90-chaperone function. Furthermore, the role of PI3K-dependent signaling in constitutive and inducible Hsp70 expression was investigated using short interfering RNA-mediated and pharmacological PI3K inhibition. Hsp72 and Hsp73 were frequently overexpressed in multiple myeloma. Knockdown of Hsp72 and/or Hsp73 or treatment with VER-155008 induced apoptosis of myeloma cells. Hsp72/Hsp73 inhibition decreased protein levels of Hsp90-chaperone clients affecting multiple oncogenic signaling pathways, and acted synergistically with the Hsp90 inhibitor NVP-AUY922 in the induction of death of myeloma cells. Inhibition of the PI3K/Akt/GSK3β pathway with short interfering RNA or PI103 decreased expression of the heat shock transcription factor 1 and down-regulated constitutive and inducible Hsp70 expression. Treatment of myeloma cells with a combination of NVP-AUY922 and PI103 resulted in additive to synergistic cytotoxicity. In conclusion, Hsp72 and Hsp73 sustain Hsp90-chaperone function and critically contribute to the survival of myeloma cells. Translation of Hsp70 inhibition into the clinic is therefore highly desirable. Treatment with PI3K inhibitors might represent an alternative therapeutic strategy to target Hsp70.

The heat shock transcription factor 1 (HSF1) has recently been reported to promote malignant transformation and growth. Here we provide experimental evidence for a role of HSF1 in the pathogenesis of multiple myeloma (MM). Immunohistochemical analyses revealed that HSF1 was overexpressed in half of the investigated MM samples, including virtually all cases with extramedullary manifestations or anaplastic morphology. HSF1 function was inhibited either by siRNA-mediated knockdown or pharmacologically through treatment with triptolide. Both approaches caused depletion of HSF1, lowered the constitutively high expression of a multitude of protective HSPs (such as HSP90, HSP70, HSP40 and HSP27), induced apoptosis in human MM cells in vitro, and strongly reduced MM tumour growth in vivo. Furthermore, we observed that treatment-induced upregulation of HSPs after proteasome or HSP90 inhibition was critically dependent on HSF1. Importantly, the apoptotic effects of the HSP90 inhibitor NVP-AUY922 or the proteasome inhibitor bortezomib were strongly enhanced in combination with triptolide, suggesting a salvage role of HSF1-dependent HSP induction in response to drug treatment. Collectively, our data indicate that inhibition of HSF1 affects multiple protective HSPs and might therefore represent a therapeutic strategy - in particular in combination with proteasome or HSP90 inhibitors.

HSP90 inhibitors effectively reduce expression and activity levels of oncogenic survival proteins. However, their clinical anti-multiple myeloma (MM) activity has been found to be rather weak, spurring the exploration of combination therapies and development of compounds with improved physicochemical properties.Preclinical effects of the novel orally bioavailable HSP90 inhibitor NVP-HSP990 on the viability, apoptosis and client protein levels of MM cells (established cell lines and clinical specimens) were tested alone and in combination with other drugs.NVP-HSP990 exerted profound activity against MM cells, with a molecular mode of action conforming well with its role as HSP90 inhibitor. Enhanced activity was most obvious in combination with melphalan. Combination with a phosphatidylinositol-3-kinase (PI3-kinase)/mammalian target of rapamycin (mTOR) inhibitor, rendered the HSP90 blockade-mediated stress response ineffective and considerably increased the anti-MM toxicity.Given the current interest in both HSP90 and PI3-kinase/mTOR as potential clinical targets, these observations could broaden the therapeutic utility of either class of inhibitor in MM.

Introduction: Current therapies for patients with r/r ALL who have had prior allogeneic hematopoietic stem cell transplantation (alloHSCT) have very poor outcomes. Improvements in the therapeutic options available for adult r/r ALL are required. Blinatumomab is a bispecific T-cell engager (BiTE®) antibody construct that redirects cytotoxic T cells to lyse CD19-positive B cells. The aim of the present analysis was to characterize a subset of patients with r/r ALL and prior alloHSCT before treatment with blinatumomab from a large confirmatory open-label, single-arm, multicenter phase 2 study (Topp MS et al Lancet Oncol 2015;16(1):57-66). Methods: Eligible patients (≥18 years) had Philadelphia chromosome-negative r/r ALL with 1 of the following negative prognostic factors: primary refractory, first relapse within 12 months of first remission, relapse within 12 months of alloHSCT, or second or greater salvage. Patients with active acute or chronic graft-versus-host disease (GvHD) were excluded. Patients were required to stop all immunosuppressive GvHD therapy within 2 weeks before starting blinatumomab. A total of 189 patients were enrolled and received blinatumomab by continuous intravenous infusion (4 weeks on/2 weeks off) for up to 5 cycles. The primary endpoint was complete remission or complete remission with partial hematologic recovery (CR/CRh) within the first 2 cycles. Secondary endpoints included overall survival (OS), relapse-free survival (RFS), and adverse events (AEs). Results: 64 (34%) patients had received alloHSCT before study enrollment; 10 patients had 2 prior alloHSCTs. Donor types primarily included 29 (45%) matched sibling and 31 (48%) unrelated, with 34 (59%) patients receiving myeloablative conditioning regimens (donor chimerism data were unavailable). Among those with prior alloHSCT, median age (range) was 32 (19-74) years. At baseline, 23 (36%) patients had 1 prior relapse, 24 (38%) had 2 prior relapses, and 17 (27%) had ≥3 prior relapses; 28 (44%) patients had relapsed post-alloHSCT. Of the 55 patients who had received previous salvage therapy, 38 (69%) had received salvage therapy after last alloHSCT and prior to blinatumomab. Median time (range) between the last alloHSCT and subsequent relapse was 6 (1-33) months. Median time from last prior alloHSCT to first dose of blinatumomab was 10 (3-40) months. Nineteen (30%) patients had a history of GvHD, and 42 (66%) had ≥50% bone marrow blasts at start of treatment as assessed by a central laboratory. Patients received blinatumomab for a median of 2 (1-5) cycles. Efficacy data are presented in Table 1. Overall, 45% (29/64; 95% confidence interval [CI], 33-58) of patients achieved CR/CRh within the first 2 cycles, with similar rates of remission also observed in the alloHSCT-naïve (42%; 52/125) group. With a median follow-up of 8.8 months, median (95% CI) OS was 8.4 (4.2-9.4) months for the 64 patients with prior alloHSCT treated with blinatumomab. Of the 29 responders (CR, n=18 and CRh, n=11), 22 (76%) had a minimal residual disease (MRD) response and 19 (66%) achieved a complete MRD response. Median RFS (95% CI) was 6.1 (5.0-7.7) months. 9/29 (31%) responders subsequently underwent another alloHSCT. In total, 56 (88%) patients had grade ≥3 treatment-emergent AEs, with the most frequent including neutropenia (22%), febrile neutropenia (20%), anemia (17%), and thrombocytopenia (14%). Six patients reported treatment-emergent GvHD (two grade ≥ 3) during blinatumomab treatment, 3 of whom had GvHD in skin. Eight patients had fatal treatment-emergent AEs, which included 1 due to gastrointestinal hemorrhage, 1 due to respiratory failure, and 6 due to infection/infestation; 1 of these (candida infection) was considered to be possibly related to treatment by the investigator. Of the subjects who had treatment-emergent fatal AEs, none were in remission at the time of death. Summary: In this heavily pretreated group of patients with r/r ALL and prior alloHSCT, single-agent blinatumomab was able to induce a CR/CRh rate of 45%, with an AE profile consistent with that previously reported. Post-alloHSCT patients who had relapsed performed equally as well as those without prior alloHSCT. To prolong remission in this poor outcome patient group, the addition of other immunotherapies to the treatment regimen may be considered for future investigations. Disclosures Stein: Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Seattle Genetics: Research Funding. Topp:Astra: Consultancy; Regeneron: Consultancy; Affimed: Consultancy, Research Funding; Roche: Consultancy, Other: Travel Support; Jazz: Consultancy; Pfizer: Consultancy; Amgen: Consultancy, Honoraria, Other: Travel Support. Goekbuget:Erytech: Consultancy; Gilead Sciences: Consultancy; Kite: Consultancy; Mundipharma: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Bayer: Equity Ownership; Sanofi: Equity Ownership; GlaxoSmithKline: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Eusapharma/Jazz: Consultancy, Honoraria, Research Funding; Medac: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; SigmaTau: Consultancy, Honoraria, Research Funding. Bargou:Pfizer: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Patents & Royalties: Patent for blinatumomab; University of Wuerzburg, Germany: Employment; GEMoaB GmbH: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Rambaldi:Roche: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Celgene: Research Funding; Pierre Fabre: Honoraria. Zhang:Amgen: Employment, Equity Ownership. Zimmerman:Amgen: Employment, Equity Ownership. Forman:Mustang: Research Funding; Amgen: Consultancy.

Introduction: Treatment of relapsed/refractory (rr) Non-Hodgkinxs lymphoma of B-cell type (B-NHL) is still challenging and new and more effective therapies are urgently warranted. Blinatumomab, a bispecific T-cell engager (BiTE®) antibody construct, engages CD3+ cytotoxic T cells, resulting in T-cell expansion and lysis of CD19+ B cells. In a prior phase I study, blinatumomab treatment resulted in an overall response rate (ORR) of 69% and 55% in diffuse large B-cell lymphoma (DLBCL), respectively for patients treated at 60 μg/m2/d. Based on this study we here present a single-center analysis on long-term outcome of patients with B-NHL after treatment with blinatumomab. We here report first preliminary data on long-term follow-up of patients with rr NHL after blinatumomab treatment. Methods: Patients with rr B-NHL who achieved an objective response (PR or CR) upon blinatumomab treatment were eligible for long-term follow-up analysis. Kaplan-Meier estimates for progression free survival (PFS) probability were calculated from first infusion to relapse or death. Patients without an event were censored at last follow-up. This study was conducted in accordance with the Declaration of Helsinki. Results: Out of 38 treated patients (17 follicular lymphoma (FL), 14 mantle cell lymphoma (MCL), 4 DLBCL, 3 others) 22 received the effective target dose of 60/90 μg/m²/d. 47,4% (CR/PR=28,9%/18,4%, n=38) and 68,2% (CR/PR=40,9%/27,3%, n=22) of the patients experienced response, respectively, whereas only 18,8% of the patients who were not treated with the effective target dose responded to blinatumomab (CR/PR=12,5%/6,3%, n=16). 6 patients are still in ongoing remission. Median overall survival (OS) of all 38 patients was 1560 days, median PFS 204 days and treatment free survival (TFS) 233 days. Median OS in the 22 patients treated with the target dose was 1793 days, median PFS 492 and TFS 752 days, compared to only 412 days median OS, 46 days PFS and 82 days TFS in the patients, who did not receive blinatumomab in an effective dosage. Conclusion: Blinatumomab has the potential to induce durable remissions in patients with rr NHL. Our data suggests that treatment at target dose of 60 μg/m²/d is an important prerequisite to achieve long-term remission. Figure 1. Kaplan Meier analysis shows significantly longer PFS in patients on target dose Figure 1. Kaplan Meier analysis shows significantly longer PFS in patients on target dose Disclosures No relevant conflicts of interest to declare.

We investigated the utility of integrin-linked kinase (ILK) as a target for therapeutic intervention in multiple myeloma (MM). ILK (over-)expression was assessed in primary samples and MM cell lines, and the molecular and physiological consequences of siRNA-mediated ILK ablation were compared to treatment with the small molecule inhibitor QLT0267. Whereas ILK expression was ubiquitous, overexpression was only rarely observed in patient biopsies. ILK knockdown had no effect on the viability or survival pathway activity pattern of MM cells. Conversely, QLT0267 induced cell death in MM cell lines and most primary tumor samples via the intrinsic apoptotic pathway. Although this effect was largely tumor cell-specific it is unlikely to have been mediated via ILK. We conclude that ILK does not play a prominent role in the promotion or sustenance of established MM.

Purpose Blinatumomab, a bispecific single-chain antibody targeting the CD19 antigen, is a member of a novel class of antibodies that redirect T cells for selective lysis of tumor cells. In acute lymphoblastic leukemia (ALL), persistence or relapse of minimal residual disease (MRD) after chemotherapy indicates resistance to chemotherapy and results in hematologic relapse. A phase II clinical study was conducted to determine the efficacy of blinatumomab in MRD-positive B-lineage ALL. Patients and Methods Patients with MRD persistence or relapse after induction and consolidation therapy were included. MRD was assessed by quantitative reverse transcriptase polymerase chain reaction for either rearrangements of immunoglobulin or T-cell receptor genes, or specific genetic aberrations. Blinatumomab was administered as a 4-week continuous intravenous infusion at a dose of 15 μg/m2/24 hours. Results Twenty-one patients were treated, of whom 16 patients became MRD negative. One patient was not evaluable due to a grade 3 adverse event leading to treatment discontinuation. Among the 16 responders, 12 patients had been molecularly refractory to previous chemotherapy. Probability for relapse-free survival is 78% at a median follow-up of 405 days. The most frequent grade 3 and 4 adverse event was lymphopenia, which was completely reversible like most other adverse events. Conclusion Blinatumomab is an efficacious and well-tolerated treatment in patients with MRD-positive B-lineage ALL after intensive chemotherapy. T cells engaged by blinatumomab seem capable of eradicating chemotherapy-resistant tumor cells that otherwise cause clinical relapse.

The huge majority of myeloma cell lines express TNFR2 while a substantial subset of them failed to show TNFR1 expression. Stimulation of TNFR1 in the TNFR1-expressing subset of MM cell lines had no or only a very mild effect on cellular viability. Surprisingly, however, TNF stimulation enhanced cell death induction by CD95L and attenuated the apoptotic effect of TRAIL. The contrasting regulation of TRAIL- and CD95L-induced cell death by TNF could be traced back to the concomitant NFκB-mediated upregulation of CD95 and the antiapoptotic FLIP protein. It appeared that CD95 induction, due to its strength, overcompensated a rather moderate upregulation of FLIP so that the net effect of TNF-induced NFκB activation in the context of CD95 signaling is pro-apoptotic. TRAIL-induced cell death, however, was antagonized in response to TNF because in this context only the induction of FLIP is relevant. Stimulation of TNFR2 in myeloma cells leads to TRAF2 depletion. In line with this, we observed cell death induction in TNFR1-TNFR2-costimulated JJN3 cells. Our studies revealed that the TNF-TNF receptor system adjusts the responsiveness of the extrinsic apoptotic pathway in myeloma cells by multiple mechanisms that generate a highly context-dependent net effect on myeloma cell survival.

We have recently shown that approximately half of primary multiple myeloma (MM) samples display constitutive Akt activity, which disposes them for sensitivity to Akt inhibition. The Akt pathway counts among the signaling conduits for oncogenic RAS and activating mutations of K- and N-RAS frequently occur in MM. We therefore analyzed the relation between RAS mutation and Akt dependency in biopsies and CD138-purified cells from MM patients (n = 65) and the function of oncogenic RAS for MM cell survival in a range of MM cell lines with differing RAS status. Whereas RAS mutations do not predict Akt dependency, oncogenic RAS retains an important role for MM cell survival. Knockdown of either K- or N-RAS strongly decreased the viability of MM cells that harbored the respective oncogenic isoform, whereas ablation of wild-type RAS isoforms had little or no effect. Silencing of oncogenic RAS did not affect the Akt pathway, again indicating lack of a direct link. Combined inhibition of RAS and Akt strongly enhanced MM cell death. These data suggest that oncogenic RAS and Akt may independently contribute to MM cell survival. Targeting of both pathways could provide an attractive therapeutic strategy for patients with oncogenic RAS and dysregulated Akt signaling.

Pharmacological inhibitors of histone deacetylases (HDACs) are currently being developed and tested as anti-cancer agents and may be useful to enhance the therapeutic efficiency of established anti-myeloma treatments. This study preclinically evaluated the effects of the 'second generation' pan-HDAC inhibitor JNJ-26481585 on human multiple myeloma (MM) cells from established cell lines and primary MM samples (n=42). Molecular responses in both groups of MM cells included histone acetylation, a shift in Bcl2-family members towards proapoptotic bias, attenuation of growth and survival pathway activity and Hsp72 induction. Mcl-1 depletion and Hsp72 induction were the most reliable features observed in JNJ-26481585-treated primary MM samples. The drug alone effectively induced myeloma cell death at low nanomolar concentrations. In vitro combination of JNJ-26481585 with anti-myeloma therapeutic agents generally resulted In effects close to additivity. In view of the favourable activity of this novel HDAC-inhibitor towards primary myeloma cells further evaluation in a clinical setting is warranted.

We have compared the cytotoxic activity of rituximab with that of blinatumomab (MT103/MEDI-538), a single-chain CD19-/CD3-bispecific antibody engaging human T cells. Blinatumomab consistently led to a higher degree of lysis of human lymphoma lines than rituximab, and was active at much lower concentration. The cytotoxicity mediated by blinatumomab and rituximab both caused a potent activation of pro-caspases 3 and 7 in target cells, a key event in induction of granzyme-mediated apoptotic cell death. Combination of rituximab with blinatumomab was found to greatly enhance the activity of rituximab, in particular at low effector-to-target cell ratios and at low antibody concentration.

Current knowledge about molecular mechanisms underlying disease progression and drug resistance in multiple myeloma (MM) is still limited. Here, we analyzed the potential pathogenetic role of the Y-box binding protein YB-1 in MM. YB-1 is a member of the cold-shock domain protein superfamily and involved in various cellular functions such as proliferation. Immunohistochemical analyses revealed that neither normal bone marrow (BM) plasma cells (PCs), premalignant PCs of patients with monoclonal gammopathy of unknown significance (MGUS), nor MM cells with a mature morphology showed expression of YB-1 in situ. In contrast, YB-1 was strongly expressed in situ in normal PC precursor blasts as well as in a MM subset and in vitro in all of the evaluated MM cell lines. The YB-1–expressing MM cells were characterized by an immature morphology and a highly proliferative phenotype as defined by Ki 67 expression. We observed that siRNA-mediated knockdown of YB-1 decreased proliferation and induced apoptosis in MM cells even in the presence of BM stromal cells. Furthermore, we found that overexpression of YB-1 mediated resistance toward doxorubicin-induced apoptosis in MM cells. Thus, YB-1 contributes to disease progression, survival, and drug resistance in MM and might therefore provide an attractive therapeutic target.

The status of the p53 pathway in classical Hodgkin lymphoma (cHL) remains unclear, and a lack of proven TP53 mutations contrasts with often high expression levels of p53 protein. In this study, we demonstrate that pharmacologic activation of the p53 pathway with the murine double minute 2 (MDM2) antagonist nutlin-3 in Hodgkin lymphoma-derived cell lines leads to effective apoptosis induction and sensitizes the cells to other anticancer drugs. Cells with mutant p53 are resistant to nutlin-3, but sensitive to geldanamycin, a pharmacologic inhibitor of heat shock 90 kDa protein (HSP90), indicating that HSP90 inhibition can induce apoptosis in a p53-independent manner. Conversely, cells with defects in the HSP90/nuclear factor-kappa B pathway expressing wild-type p53 are more resistant to geldanamycin, but still sensitive to nutlin-3. Our results suggest that selective activation of p53 by MDM2 antagonists as a single agent or in combination with conventional chemotherapeutics and/or inhibitors of p53-independent survival pathways may offer effective treatment options for patients with cHL. Importantly, because nutlins and HSP90 inhibitors are non-genotoxic agents, their use might offer a means to reduce the genotoxic burden of current chemotherapeutic regimens.

RB1,TP53, t(4;14), t(11;14), t(14;16) and a centromeric probes for chromosomes 7, 9, 11, 15 and 17 (Abbott-Vysis Inc., Downers Grove, IL, USA; Dako, Glostrup, Denmark; Kreatech, Amsterdam, The Netherlands; MetaSystems, Altlusheim, Germany). Some complex chromosomal rearrangements were analyzed by using mFISH and arrayCGH methods (MetaSystems;Agilent, Santa Clara,CA,USA). Results: Patients with the absence of delRB1 had significantly increased levels of sOPG (p 1⁄4 0.025) and sVEGF (p 1⁄4 0.036). The presence of t(11;14) was associated with lower levels of sIL-6R (p 1⁄4 0.009). The presence of t(14;16) was associated with higher levels of 2m (p 1⁄4 0.022), and lower serum levels of DKK-1 (p 1⁄4 0.023). The presence of gain 1q21 was associated with higher levels of sTK (p 1⁄4 0.026), sIL-6R (p 1⁄4 0.01), and lower serum levels of PINP (p 1⁄4 0.030). Conclusion: This showed that some cytogenetic changes have an impact on individual components of the cytokine network in MM. The presence of adverse cytogenetic changes is associated with higher levels of neoplastic mediators (sTK, sIL-6R, 2m) and a decrease in levels of bone formation parameters (sOPG, PINP and DKK-1). Identified data complete the image of biology of neoplastic processes in MM. Supported by IGA CR NT 12451/5, NT 14400, NT 14393

7051 Background: Blinatumomab is a bispecific T-cell engager antibody construct designed to link cytotoxic T cells and CD19-positive B cells, inducing tumor cell lysis. In this combined analysis, w...

7057 Background: Blinatumomab, a bispecific T-cell engager (BiTE) antibody construct, showed efficacy in r/r ALL in a large phase 2 study (Topp et al. Lancet Oncol 2015;16:57). We evaluated associa...

The combined blockade of the IL-6R/STAT3 and the MAPK signaling pathways has been shown to inhibit bone marrow microenvironment (BMM)–mediated survival of multiple myeloma (MM) cells. Here, we identify the molecular chaperones heat shock proteins (Hsp) 90α and β as target genes of both pathways. The siRNA-mediated knockdown of Hsp90 or treatment with the novel Hsp90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. Although knockdown of Hsp90β—unlike knockdown of Hsp90α—was sufficient to induce apoptosis, this effect was strongly increased when both Hsp90s were targeted, indicating a cooperation of both. Given the importance of the BMM for drug resistance and MM-cell survival, apoptosis induced by Hsp90 inhibition was not mitigated in the presence of bone marrow stromal cells, osteoclasts, or endothelial cells. These observations suggest that a positive feedback loop consisting of Hsp90α/β and major signaling pathways supports the survival of MM cells. Finally, in situ overexpression of both Hsp90 proteins was observed in most MMs but not in monoclonal gammopathy of undetermined significance (MGUS) or in normal plasma cells. Our results underpin a role for Hsp90α and β in MM pathogenesis.

Introduction: Treatment of relapsed or refractory DLBCL can be challenging and little progress has been made in recent years. Blinatumomab, a bispecific T-cell engager (BiTE®) antibody construct, engages CD3+ cytotoxic T cells, resulting in T-cell expansion and lysis of CD19+ B cells. In a prior phase 1 study, blinatumomab treatment resulted in an overall response rate (ORR) of 55% in a subset of patients with diffuse large B-cell lymphoma (DLBCL). In the present phase 2 study, we compared stepwise versus flat dosing of blinatumomab, and evaluated its efficacy in patients with relapsed/refractory (r/r) DLBCL. Methods: Eligible patients were ≥18 years of age, had an Eastern Cooperative Oncology Group performance status ≤2 and had DLBCL; patients were refractory to treatment, had relapsed following autologous HSCT, or had relapsed and were ineligible for autologous hematopoietic stem cell transplantation (HSCT). Blinatumomab was administered over 8 weeks by continuous intravenous infusion. In stage 1, stepwise dosing (cohort I: 9, 28, and 112 μg/day after weeks 1, 2, respectively) was compared to constant dosing of 112 μg/day (cohort II). Based on the benefit/risk assessment from stage 1, stepwise dosing (9, 28, and 112 μg/day) was chosen for cohort III in stage 2. Patients achieving response after 8 weeks of treatment could receive a 4-week consolidation cycle after a 4-week treatment-free period. All patients received prophylactic dexamethasone (2 × 20 mg before infusion start and at infusion start; 3 × 8 mg/day for the first 2 days after infusion start and at dose step). The primary endpoint was ORR by Cheson revised response criteria for malignant lymphomas. Response was evaluated by independent radiologic assessment. Results: As of the primary analysis, 25 patients have been enrolled and treated: 9, 2, and 14 in cohorts I, II, and III, respectively. Fifty-six percent of patients were men, and the median age was 66 years (range, 34–85). Seven (28%) patients had received prior autologous HSCT. Blinatumomab was received as a fourth-line systemic therapy following a median (range) of 3 (1-7) prior treatments. Median (interquartile range) duration of exposure for stepwise dosing (cohorts I and III) was 46.8 (22.1−76.9) days. Twenty-one patients were evaluable for response (cohort I, n=7; cohort II, n=1; cohort III, n=13). Four patients were not evaluable for ORR per protocol definition due to early treatment discontinuation (1 patient were disorientation, encephalopathy, aphasia, and epilepsy [n=2 each]). There were no grade 4 or 5 neurologic events. Conclusions: In this phase 2 study, a stepwise dosing regimen (9, 28, and 112 μg/day) was established as the preferred dosing for blinatumomab in DLBCL. Treatment with blinatumomab showed an acceptable safety profile and resulted in objective and durable responses in heavily pretreated patients with r/r DLBCL. Disclosures Viardot: Amgen Inc.: Membership on an entity's Board of Directors or advisory committees, Travel support Other; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Travel support, Travel support Other; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Travel support Other. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities.. Libicher:Amgen Inc.: Consultancy. Degenhard:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Stieglmaier:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Zhang:Amgen Inc.: Employment. Nagorsen:Amgen Inc.: Blinatumomab-related Patents & Royalties, Employment, Equity Ownership. Bargou:Amgen Inc.: Consultancy, Honoraria.

Background In multiple myeloma (MM), the introduction of novel compounds into first-line intensive treatment pathways has clearly improved patients’ prognosis. Very recently however, specific molecular cytogenetic abnormalities, lactate dehydrogenase elevation and International Staging System 3 disease were identified to be associated with dismal prognosis despite upfront autologous (auto) stem cell transplant (SCT). Consolidative allogeneic (allo) following initial auto SCT was shown to extend progression-free survival (PFS) as well as overall survival (OS) in some prospective studies on newly diagnosed MM patients (pts). Relatively little is known on the impact of cytogenetic features other than chromosome 13q deletion (del13q) on the outcomes of pts undergoing upfront auto followed by allo (auto/allo) SCT. Patients and methods When the DSMM V treatment program was designed del13q detected by fluorescence in situ hybridisation (FISH) was accepted as one of the distinct risk factors in MM. We therefore used FISH del13q to define the study’s “high-risk” group and aimed to compare tandem high-dose melphalan 200 mg/m² (Mel) with one cycle of Mel followed by reduced-intensity conditioning (RIC) allo SCT. Allocation to either transplant regimen was by availability of an HLA-matched (at least 9/10 matches) related (MRD) or unrelated donor (MUD). Initially, all pts underwent non-novel compound cytoreduction and chemomobilization of peripheral blood stem cells (PBSC). RIC allo SCT was prepared by fludarabine and melphalan (plus ATG in MUD cases). PFS was the primary endpoint. The study was powered to detect an improvement of 2-year PFS from 20% (tandem Mel) to 40.3% (HR, 1.769). Results 199 out of 225 del13q pts with a median age of 53 (range, 30 – 60) yrs who had been enrolled between 10/2001 and 03/2007, were included in the intent-to treat population. Allo SCT was performed in 126/199 pts (63%), 74 of whom (59%) received MUD allografts. At a median follow-up of 49.2 months (mo), 2-year PFS (calculated from day 1 of second SCT) was 59% with auto/allo SCT versus 47% with tandem Mel. Median PFS with auto/allo SCT was 34.5 mo versus 21.8 mo, respectively (p=.005). Two-year non-relapse mortality (NRM) associated with auto/allo SCT was 11.9%. As of yet, there is no difference in OS between the groups, with the median not yet reached for either transplant modality. PFS/OS in auto/allo SCT were independent of donor source (MRD vs MUD). As definitions of cytogenetic risk have evolved over time, we analyzed further FISH abnormalities in pts’ baseline samples: in addition to uniform del13q, 13.6% of pts displayed del17p. Median PFS for del13q/del17p pts after HD Mel was 6 mo versus not reached with auto/allo SCT, respectively (p=.0002). Median OS in del13q/del17p after HD Mel was 23.4 mo versus not reached, respectively (p=.011). In translocation (4;14)/del13q pts (20.7%), median PFS with tandem Mel was 19.3 mo versus 19.1 with auto/allo SCT, respectively (p=.251). Conclusions This prospective trial shows auto/allo SCT to significantly extend PFS when compared to tandem HD Mel in a large cohort of del13q MM pts. It is the first study to demonstrate allo SCT in MM can be safely performed from matched unrelated donors at a reasonable rate of NRM. Utilizing a comprehensive set of FISH cytogenetics, our data for the first time demonstrate allo SCT to specifically benefit patients with high-risk features (del13q/del17p). Incremental gain of PFS when compared to tandem Mel was more than 20 months. Extended OS data on the whole study will be presented. Disclosures No relevant conflicts of interest to declare.

Background Induction triplets with at least one of the “novel drugs” and steroids with or without chemotherapy are deemed standard of care in newly diagnosed multiple myeloma (MM). Medically fit patients (pts) remain candidates for subsequent autologous (auto) stem cell transplant (SCT) while the use of allogeneic (allo) SCT is an ongoing matter of debate. We had previously shown the RAD regimen to be well tolerated and highly effective in relapsed and relapsed/refractory disease. Based on the overall results we decided to further evaluate the combination in first-line treatment. Methods The current phase II trial was designed to include pts up to 65 years of age with newly diagnosed, symptomatic MM. Four 4-week RAD induction cycles (lenalidomide 25 mg/day, d 1-21; infusional adriamycin 9 mg/m², d1-4; oral dexamethasone 40 mg, d1-4 and 17-20; pegfilgrastim 6 mg, d 6) were followed by stem cell chemomobilization. Pts received either tandem auto SCT (melphalan 200 mg/m²; Mel) or auto followed by allo SCT. Allo SCT (conditioning regimen: treosulfan/fludarabine) was reserved for pts featuring at least one cytogenetic or serologic risk factor who had a matched sibling or unrelated donor available. Target dose for subsequent lenalidomide maintenance (R-maint; for one year) was 10 mg/d for tandem Mel and 5mg/d for auto/allo pts. Primary endpoint was response (at least VGPR) following second SCT. Results 190 pts with a median age of 55 (range, 30-66) years were recruited by 17 German centers between 8/2009 and 4/2012. 103 pts (56%) had ISS stage II/III disease and 165 pts are evaluable for molecular cytogenetic abnormalities assessed by fluorescence in situ hybridisation (FISH). Incidences were as follows: 29.6% had deletion of (del) chromosome 13q, 11.5% showed translocation (t) (4;14), 9% presented with del 17p, and 0.6% had a t(14;16). 163 pts completed all 4 RAD cycles and 47 underwent allogeneic SCT. 60 pts following tandem Mel and 15 pts after auto-allo SCT proceeded to R-maint. Median number of maintenance cycles was significantly higher in tandem Mel compared with auto-allo pts (12 versus 3; p=.01). Rate of at least (≥) VGPR increased from 47.9% following RAD induction to 60.6% following double SCT. Accordingly, post-induction complete response (CR)/stringent CR rate of 7.9% increased to 31%. In pts with FISH results, ≥ VGPR rate was 44% with t(4;14)/t(14;16)/del 17p versus 53% without those abnormalities, respectively (p=.34). Following double SCT, ≥ VGPR was increased to 63% [t(4;14)/t(14;16)/del 17 pts.] versus 65%, respectively (p=.84). Response was not different with either transplant strategy. No treatment-related mortality occurred during RAD induction, while non-relapse mortality at one year from allo SCT was 10.6%. Incidences of pneumonia, venous thromboembolism, and febrile neutropenia were 11, 7.2, and 5.3%, respectively. Preliminary overall survival results will be presented. Conclusions Our data show RAD induction to be very effective in newly diagnosed MM and to be well tolerated. By subsequent double SCT, a high number of CR/sCR was added. Correlative studies suggests response to be independent of known unfavourable cytogenetic prognosticators, such as t(4;14) and del 17p while time-to-event data will be needed to ultimately confirm a lenalidomide-based triple regimen being able to overcome adverse cytogenetic risk. Administration of R-maint to auto-allo pts was challenging despite a lenalidomide target dose of 5 mg/day. Disclosures Knop: Celgene GmbH: Consultancy, Honoraria. Off Label Use: Use of lenalidomide, doxorubicin, and dexamethasone in newly diagnosed multiple myeloma. Einsele:Celgene GmbH: Consultancy, Research Funding. Bargou:Amgen Inc.: Consultancy, Honoraria, Other.

Introduction: In ALL, minimal residual disease (MRD) is defined as the detection of leukemic cells in bone marrow by PCR or flow cytometry in the presence of hematological complete remission (CR). Patients with persistent/recurrent MRD after induction therapy have a higher risk of relapse than those with no detectable MRD. Effective treatment of patients with MRD aims to avoid hematologic relapse, reduce MRD load, and provide a bridge to subsequent HSCT. Blinatumomab, an investigational BiTE® antibody construct, redirects CD3+ T cells to CD19+ target cells, resulting in serial lysis of CD19+ B cells. In a phase 2 study of blinatumomab in 21 patients with MRD+ ALL in first-line treatment, 80% of evaluable patients achieved a complete MRD response. BLAST, a confirmatory single-arm, phase 2 study evaluated efficacy, safety, and tolerability of blinatumomab in patients with MRD+ ALL in a larger population. Methods: Adults (≥18 years) with B-precursor ALL in hematologic CR ( Results: 116 patients enrolled and received blinatumomab. Median (range) age was 45 (18–76) years; 15 (13%) patients were ≥65 years of age. 35% of the patients were treated in second or later remission (Table). As of February 2014, 106 patients had ended treatment: 74 had completed treatment (4 cycles or 1 cycle followed by HSCT) and 32 had discontinued treatment due to AEs, disease relapse, or investigators' decision; 79 patients were still alive and being followed. Three patients were excluded from the efficacy analysis: one had no central lab assay and two had assays with a sensitivity of 5×10-4. Eighty-eight patients (78% [95% CI, 69%–85%]) had a complete MRD response after 1 cycle of treatment. The lower CI bound exceeded 44% (the null hypothesis response rate), confirming that the study met its primary objective. Two additional patients had a complete MRD response after >1 cycle of blinatumomab; across all cycles the complete MRD response rate was 80%. The rate of complete MRD response did not differ significantly across baseline age, sex, line of treatment, and MRD burden categories (Table). All patients experienced ≥1 AE. AEs occurring in ≥20% of patients included pyrexia (88%), headache (38%), tremor (29%), chills (25%), fatigue (24%), nausea (22%) and vomiting (22%). Serious AEs (SAEs) occurred in 60% of patients; 59% and 27% of patients had grade ≥3 and grade ≥4 AEs, respectively. SAEs occurring in ≥5% of patients were pyrexia (15%), tremor (7%), aphasia (5%), encephalopathy (5%) and overdose (5%). Two fatal AEs occurred on treatment: subdural hemorrhage and atypical pneumonia (the latter was deemed treatment-related). Conclusion: This is the largest prospective trial with an experimental compound in MRD+ ALL.Blinatumomab treatment resulted in complete MRD response across multiple patient demographics including patients in second-line treatment and those with high MRD burden. With a complete MRD response rate of 78%, the study met its primary objective. Among patients with a complete MRD response, 98% had a response within the first treatment cycle. In patients with MRD+ ALL following intensive therapy, rapid MRD response induced by blinatumomab has the potential to improve patient outcomes. Figure 1 Figure 1. Disclosures Goekbuget: Amgen Inc.: Consultancy, Honoraria, Research Funding. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities.. Dombret:Amgen Inc.: Honoraria, Research Funding. Bonifacio:Amgen Inc.: Consultancy. Graux:Amgen Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees. Buss:Amgen Inc.: Reimbursement for participation in clinical studies, Reimbursement for participation in clinical studies Other; BMS: Travel support, Travel support Other; Novartis: Travel support Other; Pfizer: Reimbursements for participation in clinical studies, Reimbursements for participation in clinical studies Other. Bruggemann:Amgen Inc.: Consultancy, Research Funding. Stieglmaier:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Wessels:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Haddad:Amgen Ltd.: Employment. Zugmaier:Amgen Research (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Nagorsen:Amgen Inc.: Employment, Equity Ownership, Related to blinatumomab Patents & Royalties. Bargou:Amgen Inc.: Consultancy, Honoraria.

Introduction: Improvements in the therapeutic options available for adult relapsed/refractory (r/r) B-precursor ALL are required. Blinatumomab is an investigational bispecific T-cell engager (BiTE®) antibody construct that redirects cytotoxic T cells to lyse CD19-positive B cells. Based on encouraging clinical data from a small phase 2 study (Topp MS et al. J Clin Oncol. 2014;32(15s): abstract 7005), we conducted a large confirmatory open-label, single-arm, multicenter phase 2 study of blinatumomab in patients with r/r B-precursor ALL. The aim of the present analysis from this phase 2 study was to characterize those patients who proceeded to allogeneic hematopoietic stem cell transplantation (HSCT) after achieving complete remission (CR)/complete remission with partial hematologic recovery (CRh*) with blinatumomab treatment. Methods: Eligible patients (≥18 years) had Philadelphia chromosome-negative r/r B-precursor ALL with one of the following negative prognostic factors: primary refractory, 1st relapse within 12 months of 1st remission, relapse within 12 months of HSCT, or ≥2nd salvage. Blinatumomab was given by continuous IV infusion (4 weeks on/2 weeks off) for up to 5 cycles. The primary endpoint was CR/CRh* within the first 2 cycles. Secondary endpoints included overall survival (OS), relapse-free survival (RFS), HSCT realization rate, 100-day mortality following HSCT, and adverse events. Results: 189 patients with a median age (range) of 39 (18‒79) years were enrolled and received blinatumomab for a median (range) of 2 (1‒5) cycles. At enrollment, 74 (39%) patients had received ≥2 prior salvage therapies, 64 (34%) had received prior HSCT, and 105 (56%) had ≥75% bone marrow blasts. 43% (81/189) of patients achieved CR/CRh* within 2 cycles, with similar rates of remission observed in both the HSCT-naïve (42%; 52/125) and prior HSCT (45%; 29/64) groups. In total, 32/81 responders (CR, n=28 and CRh*, n=4) underwent HSCT during blinatumomab-induced remission, yielding a transplantation realization rate for blinatumomab responders of 40% (Table 1). 52% (27/52) of the HSCT-naïve patients and 17% (5/29) of patients who had received prior HSCT proceeded to on-study HSCT during blinatumomab-induced remission. These 32 transplants occurred after a median of 2 (1-5) cycles of therapy, with 11 (34%) patients receiving myeloablative conditioning pre-HSCT, 12 (38%) reduced intensity conditioning, and 9 (28%) unknown regimens. Twenty-two (69%) patients used unrelated donors (stem cells derived from blood, n=11; bone marrow, n=6; cord blood, n=5), 7 (22%) used related donors including 6 siblings (blood, n=5; bone marrow, n=1) and 1 haploidentical mother (blood), with 3 (9%) donor types and stem cell sources unknown. Six patients achieving CR/CRh* after 2 cycles of blinatumomab underwent HSCT but were not included in the transplantation realization rate of 40% due to receiving subsequent antineoplastic therapy before HSCT conditioning (Table 1). Among the 43 patients who achieved CR/CRh* within 2 cycles of blinatumomab treatment but never reached HSCT, 20 (47%) had undergone prior HSCT, 7 (16%) were ≥65 years, and 2 (5%) were ≥65 years and had received prior HSCT (Table 1). Figure 1 Figure 1. At the time of the primary analysis (data cut-off in October 2013), with median follow-up of 9.8 months, median (95% CI) OS for the 189 blinatumomab-treated patients was 6.1 (4.2‒7.5) months. When censoring for HSCT, median OS was 5.1 (4.1‒7.1) months; although the medians are slightly different, the curves with and without HSCT censoring largely overlap. Median RFS was 5.9 months with and without censoring for HSCT. Nine patients died at any time after HSCT, with 5 deaths due to infection, 3 due to disease progression, and 1 due to graft-versus-host disease (GvHD). Three of these deaths (2 infections and 1 GvHD) were within 100 days of HSCT. The 100-day post-HSCT mortality rate was 11%. Summary: This large phase 2 study demonstrated antileukemia activity of single-agent blinatumomab in heavily pretreated or aggressive r/r ALL, irrespective of prior HSCT. The data suggest that blinatumomab enables patients to reach HSCT, with 11% 100-day mortality post-HSCT. Two-thirds of patients who did not reach HSCT after responding to blinatumomab were either ≥65 years old or had received prior HSCT. Longer follow-up is required to assess the role of HSCT in patients achieving CR/CRh* after treatment with blinatumomab. Disclosures Stein: Amgen Inc.: Membership on an entity's Board of Directors or advisory committees. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities.. Topp:Amgen Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees. Goekbuget:Amgen Inc.: Consultancy, Honoraria, Research Funding. Bargou:Amgen Inc.: Consultancy, Honoraria. Dombret:Amgen Inc.: Honoraria, Research Funding. Larson:Amgen Inc.: Consultancy, Research Funding. Rambaldi:Amgen Inc.: Consultancy. Zugmaier:Amgen Reseach (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Jia:Amgen Inc.: Employment, Equity Ownership. Maniar:Amgen Inc.: Employment, Equity Ownership. Huber:Amgen Research (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Nagorsen:Amgen Inc.: Employment, Equity Ownership, Related to blinatumomab Patents & Royalties. Kantarjian:Amgen Inc.: Research Funding; ARIAD: Research Funding; Pfizer: Research Funding.

Background: Blinatumomab is an investigational bispecific T-cell engager (BiTE®) antibody construct designed to direct cytotoxic T cells to CD19-expressing B cells. In a study in minimal residual disease (MRD)-positive ALL, 80% of pts achieved MRD-negative status after receiving one treatment cycle of blinatumomab (Topp MS, et al. J Clin Oncol. 2011;29:2493-8). For pts with newly diagnosed ALL, persistence of MRD after first-line treatment predicts disease recurrence. However, only limited data are available about the relationship between MRD and outcome in adult pts with r/r ALL. Therefore, the aim of this secondary analysis was to evaluate MRD responses and their relationships to other efficacy indices in adult pts with r/r ALL receiving blinatumomab in this phase 2 study. Methods: Eligibility criteria included adult pts ≥18 years, with Philadelphia chromosome negative B-cell r/r ALL who were primary refractory or refractory to first salvage, had their first relapse within 12 months of first remission or allogeneic hematologic stem cell transplantation (HSCT), or received second or later salvage. Blinatumomab was dosed via continuous IV infusion at 28 μg/d (cycle 1 only: 9 μg/d on days 1-7, 28 μg/d on days 8-28) for up to five cycles (one cycle: 4 weeks on, 2 weeks off). The primary endpoint was complete remission (CR: ≤5% blasts with platelets >100,000/µL, absolute neutrophil count >1000/µL) or CR with partial hematologic recovery (CRh*: platelets >50,000/µL, absolute neutrophil count >500/µL) within the first two treatment cycles. MRD in bone marrow was assessed at a central laboratory using allele-specific real-time quantitative PCR. Two MRD-based exploratory endpoints were analyzed: MRD response (no PCR amplification at a minimum sensitivity of 10-4 or Results: Of 189 treated pts (median [range] age = 39 [18–79] years), 81 (43%) pts had a CR (n = 63, 33%) or a CRh* (n = 18, 10%) during the first two treatment cycles. In the subgroup of pts with a CR/CRh* and evaluable MRD data (n = 73), 60 (82%) pts had an MRD response. Of those, 51 (70%) pts had a complete MRD response. The majority of those who achieved a CR/CRh* also achieved a complete MRD response regardless of the number of prior lines of salvage therapy (Table 1). Of all treated pts, 64 (34%) pts had prior HSCT. In pts who achieved CR/CRh*, the rate of MRD response was 81% in pts without and 85% in pts with prior HSCT. In pts who achieved CR/CRh*, the median (95% CI) duration of overall survival was 11.4 (8.5, not estimable) months for those with a MRD response and 6.7 (2.0, not estimable) months for those with no MRD response. The median (95% CI) duration of relapse-free survival was 6.9 (5.5, 10.1) months in patients with a MRD response and 2.3 (1.2, not estimable) months in patients with no MRD response. The HSCT realization rate did not differ significantly between pts with CR/CRh* and a MRD response and those with CR/CRh* and no MRD response (31% and 43%, respectively). Seventeen pts classified as nonresponders per protocol had ≤5% blasts and no evidence of disease, but recovery of peripheral counts did not meet criteria for CRh*. Ten of these 17 pts had evaluable MRD assessments; 50% (5/10) had MRD response and 20% (2/10) had complete MRD response. The clinical significance of this finding remains open. Grade ≥3 adverse events regardless of causality and occurring in >10% of all treated pts during treatment until 30 days after treatment were febrile neutropenia (25%), neutropenia (16%), and anemia (14%). Grade 3 cytokine release syndrome (CRS) was reported in three (1.6%) patients. Three (1.6%) patients had grade 4 neurologic events, all resolved. Twenty-one (11%) patients had grade 3 neurologic events, 17 were resolved, with 4 events unresolved at death or unknown. Conclusion: In this largest study to date of adult pts with r/r ALL with PCR-based central assessment of MRD, pts who achieved CR/CRh* during single-agent treatment with blinatumomab had high MRD response rates. The exploratory analyses suggested that within pts with a CR/CRh*, those who did not achieve MRD responses tended to have shorter durations of overall and relapse-free survival. These results are consistent with prior reports highlighting the importance of achieving an MRD response in first-line therapy. Disclosures Goekbuget: Amgen Inc.: Consultancy, Honoraria, Research Funding. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities. Kantarjian:Amgen Inc.: Research Funding. Brüggemann:Amgen Inc.: Consultancy, Research Funding. Stein:Amgen Inc.: Membership on an entity's Board of Directors or advisory committees. Bargou:Amgen Inc.: Consultancy, Honoraria. Dombret:Amgen Inc.: Research Funding. Heffner:Amgen Inc.: Honoraria, Research Funding; Biotest: Research Funding; Dana Farber CI: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Idera: Research Funding; Janssen: Research Funding; Pfizer: Research Funding; Pharmacyclics: Honoraria, Research Funding; Onyx: Research Funding; Spectrum: Research Funding; Talon Therapeutics: Research Funding. Rigal-Huguet:Amgen, Inc.: Consultancy; Ariad: Consultancy; BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy. Litzow:Amgen Inc.: Honoraria, Research Funding. Zugmaier:Amgen Reseach (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Jia:Amgen Inc.: Employment, Equity Ownership. Maniar:Amgen Inc.: Employment, Equity Ownership. Huber:Amgen Research (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Nagorsen:Amgen Inc.: Employment, Equity Ownership, Related to blinatumomab Patents & Royalties. Topp:Amgen Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Introduction: Relapsed/refractory (r/r) B-precursor ALL in adults has an unfavorable prognosis with a median overall survival of 4–8 months and a 5-year survival of Methods: The primary endpoint was hematologic complete remission (CR) or CR with partial hematologic recovery (CRh*) within 2 cycles of blinatumomab. Secondary endpoints included rate of minimal residual disease (MRD) response (defined as < 10-4), overall survival (OS), and relapse-free survival (RFS). Blinatumomab was administered by continuous intravenous infusion for 28 days followed by a 14-day treatment-free interval. Responding patients had the option to receive 3 additional cycles of treatment or to proceed to allogeneic hematopoietic stem cell transplantation (aHSCT). Results: 36 patients were treated; 25 (69%) responded, with 15 (42%) achieving CR and 10 (28%) CRh*. MRD response was achieved in 22 (88%) of these 25 patients with CR or CRh*. Thirteen patients with CR or CRh* proceeded to aHSCT after blinatumomab treatment. In addition, one patient with hypocellular bone marrow and MRD response after the first cycle underwent aHSCT. Follow-up for RFS is 22.4 months; median RFS is 8.8 months. Median follow-up for OS is 30.2 months; median OS is 12.9 months. Ten patients (28%) are alive at 29.7 months (Figure). We analyzed the characteristics of the 10 living long-term survivors, defined as OS of 2 years or longer, seven of whom were relapse-free. The age of these 10 patients at the time of first infusion ranged from 21 to 72 years; the blast count at screening ranged from 8% to 97% (median, 56%). Four of the 10 patients alive had received aHSCT prior to blinatumomab treatment. Of the six patients without a prior aHSCT, two were primary refractory; two had the first relapse within 12 months and two after 12 months post first diagnosis. In the 10 surviving patients blinatumomab treatment induced CR in seven patients, CRh* in two patients, and blast-free hypo-cellular bone marrow in one patient. All 10 surviving patients had an MRD response following blinatumomab treatment. The patient with hypocellular bone marrow received a transplant after the first cycle before potential recovery of blood counts qualifying for CR/CRh* could occur. Seven of the surviving patients underwent aHSCT after blinatumomab, including four patients who received a second aHSCT after they had already received an aHSCT prior to blinatumomab. One of the three patients who did not undergo aHSCT after CRh* had grade 4 cytokine release syndrome requiring resuscitation after 1 day of blinatumomab treatment and has remained in ongoing remission for 22 months without any further treatment aside from 5 cycles of blinatumomab. Another one of these three patients, who had a grade 3 neurologic event on day 2 of cycle 2, has remained in ongoing remission for 34 months without any further treatment aside from 5 cycles of blinatumomab. The third of these three patients had two CD19-positive relapses after CR following blinatumomab treatment. The patient was retreated with 3 cycles of blinatumomab, resulting twice in CR and MRD response. Two of the 10 surviving patients relapsed after blinatumomab and aHSCT; one patient with a CD 19-negative relapse achieved another hematologic remission by chemotherapy. Summary: These data show that patients with r/r ALL, who achieved MRD response and received subsequent aHSCT following blinatumomab immunotherapy may achieve long-term survival longer than 2 years. Studies with a larger sample size are warranted to confirm these data. Two patients with grade 3 or 4 toxicities showed long-term survival without aHSCT after blinatumomab. Figure Figure. Disclosures Zugmaier: Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Off Label Use: This presentation will discuss the off-label use of blinatumomab, as this agent is not approved for use by the FDA, EMA or any other regulatory authorities.. Goekbuget:Amgen Inc.: Consultancy, Honoraria, Research Funding. Viardot:Amgen Inc.: Membership on an entity's Board of Directors or advisory committees, Travel support Other; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Travel support, Travel support Other; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Travel support Other. Horst:Amgen Inc.: Honoraria, Research Funding. Brueggemann:Amgen Inc.: Consultancy, Research Funding. Holland:Amgen Inc.: Employment, Equity Ownership. Schmidt:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Mergen:Amgen Inc.: Equity Ownership; Amgen Research (Munich) GmbH: Employment. Bargou:Amgen Inc.: Consultancy, Honoraria. Topp:Amgen Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Multiple myeloma is a bone marrow plasma cell tumor which is supported by the external growth factors APRIL and IL-6, among others. Recently, we identified eosinophils and megakaryocytes to be functional components of the micro-environmental niches of benign bone marrow plasma cells and to be important local sources of these cytokines. Here, we investigated whether eosinophils and megakaryocytes also support the growth of tumor plasma cells in the MOPC315. BM model for multiple myeloma. As it was shown for benign plasma cells and multiple myeloma cells, IL-6 and APRIL also supported MOPC315. BM cell growth in vitro, IL-5 had no effect. Depletion of eosinophils in vivo by IL-5 blockade led to a reduction of the early myeloma load. Consistent with this, myeloma growth in early stages was retarded in eosinophil-deficient Delta dblGATA-1 mice. Late myeloma stages were unaffected, possibly due to megakaryocytes compensating for the loss of eosinophils, since megakaryocytes were found to be in contact with myeloma cells in vivo and supported myeloma growth in vitro. We conclude that eosinophils and megakaryocytes in the niches for benign bone marrow plasma cells support the growth of malignant plasma cells. Further investigations are required to test whether perturbation of these niches represents a potential strategy for the treatment of multiple myeloma.

Most of the drugs currently used to treat hematologic cancers are genotoxic agents that exert some of their antitumor activity through p53-dependent mechanisms. However, this activity is achieved at the price of collateral genotoxic damage, which may lead to generation of more malignant tumor subclones and secondary neoplasias. Because p53 remains wild-type in the majority of hematologic malignancies nongenotoxic induction of the p53-pathway is an attractive therapeutic strategy for this group of cancers. Following the recent development of selective small-molecule MDM2-antagonists (nutlins), we have demonstrated that nutlin-treatment of primary tumor cells isolated from patients with multiple myeloma induces p53 target genes and efficiently drives these cells into apoptosis. Because the apoptotic function of p53 appears to be preserved in a number of common hematologic neoplasias it should be used to investigate the utility of non-genotoxic p53-induction therapies.