Therapeutic Options For Multiple Myeloma Research Articles

Identification of EpHA3 As a New Potential Molecular Target in Multiple Myeloma.

AbstractAbstract 2926 IntroductionAngiogenesis plays a central role in the progression of both solid and hematological tumors. In particular, in multiple myeloma (MM) the critical role of bone marrow (BM) microenvironment and angiogenesis has been well documented. The past decade has witnessed a dramatic improvement in the therapeutic options in MM. However, the disease remains incurable, underscoring the need for continued efforts towards understanding MM biology and exploitation of novel therapeutic approaches. In this setting, monoclonal antibodies against myeloma-specific cell surface antigens represent a promising therapeutic approach, which is however hampered by a lack of appropriate target structures expressed across all pathogenic myeloma cells.The Eph receptors, a large family of receptor tyrosine kinases (RTKs) activated by ephrins binding, have been implicated in many processes involved in malignancy, including alteration of the tumor microenvironment and in angiogenesis, in both of which EpHA3 likely plays an active role. Aberrant expression of EpHA3 is seen in many types of hematolologic malignancies (some leukemic cell lines, T-cell lymphoma, acute lymphoblastic leukemia, myeloproliferative neoplasms) although it is not expressed ubiquitously. Finally, the over-expression of Eph is believed to be sufficient to confer tumorigenic potential although probably further mechanisms can occur to abnormally activate the receptor.Basing on the role of EpHA3 in haematological malignancies, a first-in-class engineered IgG1 antibody targeting the EpHA (KB004) was developed and it is now under phase I clinical trials in USA and Australia for the treatment of EpHA3 overexpressing hematological myeloid malignancies refractory to conventional treatment.We investigated the EpHA3 role and its preferential membrane–bound by GPI linker ligand EFNA5, in MM patients in order to define EpHA3 as new molecular target for a novel therapeutic approach with a specific anti EpHA3 monoclonal antibody. The EpHA3 expression has been studied through a comparative proteomic analysis between BM endothelial cells (ECs) of patients with MM (MMECs) or with monoclonal gammopathy of undetermined significance (MGECs), of control subjects (normal ECs) and in MM cell lines. MethodsAfter written informed consent, BM aspirates have been collected from 20 MM and 4 MGUS patients. Normal ECs were derived from 3 BM aspirates of subjects with anemia due to iron or vitamin B12 deficiency. We analyzed the expression levels of EpHA3 in normal ECs, MGECs and MMECs and MM cell lines evaluating the mRNA and protein levels by RT-qPCR and by WB coupled to ImmunoFluorescence analysis. The biological effects of EpHA3 targeting in MMECs have been studied silencing the EpHA3 mRNA in MMECs and testing them at 72h after silencing in series of functinal assays including viability assay by trypan blue exclusion staining and by in vitro angiogenesis assay followed by measurement of mesh areas and vessel length. Moreover, we studied EFNA5 mRNA expression levels in Normal ECs, MGECs and MMECs and in MM cell lines by PCR. ResultsOur data showed that EpHA3 mRNA levels are progressively increased from ECs to MGECs reaching the highest values in MMECs. Subsequent analysis by WB and immunofluorescence confirmed EpHA3 protein upregulation among the different EC types. The MMECs in which EpHA3 has been silenced revealed a protein level reduction of approximately 60% when compared to the control. We could not detect major viability defects. Furthermore, in vitro angiogenesis inhibition was marginal when compared to the not silenced counterpart. To know whether EpHA3 may impact not only MM angiogenesis but also plasma cells, three MM cell lines were studied for the EpHA3 expression. We found the plasma cell lines gave constant over expression of EpHA3. Finally, the preliminary data regarding EFNA5 mRNA expression level showed it is expressed in either MMECs and MM plasma cell lines.The evaluation of KB004 effect on MMECs in term of apoptosis induction and in vitro tube formation inhibition, as well as the analysis of EpHA3 levels in primary MM plasma cells are in progress. ConclusionsFrom this study we expect to characterize the role of the EpHA3in MM patients and to provide experimental evidences supporting the possibility of using EpHA3 as a new molecular target for MM by proving the in vitro efficacy of a monoclonal antibody to target the angiogenesis of MM. Disclosures:No relevant conflicts of interest to declare.

Blockade of XBP1 splicing by inhibition of IRE1α is a promising therapeutic option in multiple myeloma

AbstractMultiple myeloma (MM) cells are characterized by high protein synthesis resulting in chronic endoplasmic reticulum (ER) stress, which is adaptively managed by the unfolded protein response. Inositol-requiring enzyme 1α (IRE1α) is activated to splice X-box binding protein 1 (XBP1) mRNA, thereby increasing XBP1s protein, which in turn regulates genes responsible for protein folding and degradation during the unfolded protein response. In this study, we examined whether IRE1α-XBP1 pathway is a potential therapeutic target in MM using a small-molecule IRE1α endoribonuclease domain inhibitor MKC-3946. MKC-3946 triggered modest growth inhibition in MM cell lines, without toxicity in normal mononuclear cells. Importantly, it significantly enhanced cytotoxicity induced by bortezomib or 17-AAG, even in the presence of bone marrow stromal cells or exogenous IL-6. Both bortezomib and 17-AAG induced ER stress, evidenced by induction of XBP1s, which was blocked by MKC-3946. Apoptosis induced by these agents was enhanced by MKC-3946, associated with increased CHOP. Finally, MKC-3946 inhibited XBP1 splicing in a model of ER stress in vivo, associated with significant growth inhibition of MM cells. Taken together, our results demonstrate that blockade of XBP1 splicing by inhibition of IRE1α endoribonuclease domain is a potential therapeutic option in MM.

Blockade of XBP1 Splicing by Inhibition of IRE1α Is a Promising Therapeutic Option in Multiple Myeloma

Abstract 133Multiple myeloma (MM) cells are characterized by high protein synthesis resulting in chronic endoplasmic reticulum (ER) stress, which is adaptively managed by the unfolded protein response (UPR). Therefore blockade of UPR could provide a novel therapeutic option in MM. Upon UPR, inositol-requiring enzyme 1α (IRE1α) is activated by auto-phosphorylation, resulting in activation of its endoribonuclease domain to cleave XBP1 mRNA from XBP1 unspliced form (XBP1u: inactive) to generate the XBP1 spliced form (XBP1s: active). XBP1s protein in turn regulates genes responsible for protein folding and degradation, playing a pro-survival signaling role in the UPR. In this study, we specifically examined whether IRE1α-XBP1 pathway is a potential therapeutic target in MM. We first examined the biologic significance of IRE1α by knockdown using lentiviral shRNA and observed significant growth inhibition in IRE1α knockdown cells. We next examined the impact of inhibition of XBP1 splicing using a novel small molecule IRE1α endoribonuclease domain inhibitor MKC-3946 (MannKind, Valencia CA). MKC-3946 blocked not only the basal level, but also inducible (by tunicamycin) XBP1s, evidenced by RT-PCR analysis in RPMI8226 cells, without affecting phosphorylation of IRE1α. Importantly, MKC-3946 also inhibited XBP1s in primary tumor cells from MM patients. We also confirmed functional inhibition of XBP1s, with target genes including SEC61A1, p58IPK, and ERdj4 downregulated by MKC-3946 treatment. Importantly, MKC-3946 triggered growth inhibition in MM cell lines, without toxicity in normal mononuclear cells. Furthermore, it significantly enhanced cytotoxicity induced by bortezomib or 17-AAG in RPMI8226 and INA6 cells, as well as primary tumor cells from MM patients. Both bortezomib and 17-AAG induced ER stress with XBP1s, which was markedly blocked by MKC-3946. Moreover, apoptosis induced by bortezomib or 17-AAG was enhanced by MKC-3946, associated with increased CHOP mRNA and protein, a proapoptotic factor triggered by ER stress. We next demonstrated that XBP1s was induced by bortezomib in INA6 cells co-cultured with bone marrow (BM) stromal cells, which was inhibited by MKC-3946, associated with enhanced cytotoxicity induced by the combination. Finally, MKC-3946 inhibited XBP1s in a model of in vivo ER stress induced by tunicamycin. To evaluate the anti-MM effect of MKC-3946, we used the subcutaneous RPMI8226 xenograft model in mice. MKC-3946 significantly reduced MM tumor growth in the treatment versus control group, associated with prolonged overall survival. We also confirmed that MKC-3946 treatment significantly inhibited XBP1s in excised tumors, assessed by RT-PCR. In order to examine the activity of MKC-3946 on MM cell growth in the context of the human BM microenvironment in vivo, we used the SCID-hu model, in which INA6 cells are directly injected into a human bone chip implanted subcutaneously in SCID-mice. MKC-3946 treatment significantly inhibited tumor growth compared with vehicle control. Moreover, XBP1s in excised tumor cells was inhibited, evidenced by RT-PCR. In conclusion, these data demonstrate that blockade of XBP1s by MKC-3946 triggers MM cell growth inhibition in vivo and prolongs host survival. Taken together, our results demonstrate that blockade of XBP1 splicing by inhibition of IRE1α endoribonuclease domain is a potential novel therapeutic option in MM. Disclosures:Tam:MannKind Corporation: Employment, Equity Ownership. Zeng:MannKind Corporation: Employment, Equity Ownership. Patterson:MannKind Corporation: Employment, Equity Ownership. Richardson:Bristol Myers Squibb: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity’s Board of Directors or advisory committees; Celgene: Membership on an entity’s Board of Directors or advisory committees; Millennium: Membership on an entity’s Board of Directors or advisory committees. Munshi:Millennium: Membership on an entity’s Board of Directors or advisory committees; Celgene: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees. Anderson:Millennium: Membership on an entity’s Board of Directors or advisory committees; Onyx: Membership on an entity’s Board of Directors or advisory committees; MannKind: Membership on an entity’s Board of Directors or advisory committees.

Targeting IRE1α-XBP1 Pathway Is a Novel Therapeutic Strategy In Multiple Myeloma

AbstractAbstract 4074Aberrant protein folding results in the accumulation of misfolded/unfolded proteins in the endoplasmic reticulum (ER), which in turn triggers ER stress followed by unfolded protein response (UPR), an adaptive response against ER stress. Since multiple myeloma (MM) cells have high protein synthesis, they are sensitive to ER stress and require strict ER quality control for cell survival. Upon UPR, IRE1α is activated by auto-phosphorylation resulting in activation of its endoribonuclease domain to splice XBP1 mRNA from XBP1 unspliced form (XBP1u: inactive) to XBP1 spliced form (XBP1s: active). Since XBP1 is a transcription factor regulating genes which are responsible for protein folding and ER associated degradation (ERAD), IRE1α-XBP1 pathway acts as a pro-survival signaling pathway under the UPR condition. In this study, we examined whether IRE1α-XBP1 pathway is a potential novel therapeutic option in MM. We first examined IRE1α expression and confirmed its expression in all MM cell lines. In contrast, XBP1s was not detected by RT-PCR in most cell lines except in for RPMI8226 cells. To assess biologic significance of IRE1α in MM cell, we knock-downed its expression using shRNA and found that downregulation of IRE1α inhibited MM cell growth, indicating that IRE1α has a crucial role in MM cell survival. We next examined the impact of inhibition of XBP1 splicing by a small molecule IRE1α endoribonuclease inhibitor MKC-3946 (Mannkind, Valencia CA) in MM cells in vitro. As expected, MKC-3946 significantly inhibited tunicamycin-induced XBP1s without affecting phosphorylation of IRE1α. MKC-3946 induced only modest cytotoxicity in MM cell lines without toxicity in normal mononuclear cells from healthy donors; however, it significantly enhanced cytotoxicity in combination with bortezomib or 17-AAG. Both bortezomib and 17-AAG induced ER stress evidenced by induction of XBP1s; conversely, MKC-3946 blocked XBP1s triggered by these agents. Furthermore, apoptosis induced by these agents was enhanced with MKC-3946 associated with increased CHOP, which is a known pro-apoptotic protein induced in uncompensated ER stress condition. Importantly, MKC-3946 enhanced the cytotoxicity of bortezomib or 17-AAG in INA6 cells, even in the presence of increased IL-6 or bone marrow stromal cells. Finally, MKC-3946 was active inhibiting XBP1 splicing in a model of ER stress and significantly inhibited growth of RPMI8226 plasmacytoma in a xenograft murine model when used in combination with a low dose of bortezomib. Taken together, our results demonstrate that inhibition of XBP1 splicing by blockade of IRE1α is a promising therapeutic option in MM. Disclosures:Blumenthal:Mannkind Corporation: Employment, Equity Ownership. Tam:Mannkind Corporation: Employment, Equity Ownership. Kertesz:Mannkind Corporation: Employment, Equity Ownership. Zeng:Mannkind Corporation: Employment, Equity Ownership. Patterson:Mannkind Corporation: Employment, Equity Ownership. Munshi:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Richardson:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees. Anderson:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

Interleukin-16 Is An Important Growth-Promoting Factor and a Novel Diagnostic and Therapeutic Target for Multiple Myeloma

AbstractAbstract 4056 Background:Multiple myeloma (MM) is a malignancy characterized by the expansion of a plasma cell (PC) clone that localizes to the bone marrow (BM). Myeloma cells and BM stromal cells both produce soluble factors promoting the survival and progression of MM. Interleukin-(IL)-16 is involved in regulating migration and proliferation of normal leukocytes, however, it has been unclear whether IL-16 also plays a role in the pathophysiology of human cancers. Methods:Using an antibody array we screened supernatants of myeloma cell lines for the presence of a variety of cytokines/chemokines. We confirmed IL-16 expression in myeloma cell lines as well as in malignant PC and BM plasma from MM patients applying real-time PCR, western blots, ELISA, and flow cytometry. We applied inhibitory RNA to analyze IL-16 function and we used anti-IL-16 antibodies to evaluate possible therapeutic options for MM. Results:We found IL-16 to be strongly overexpressed in the BM of myeloma patients. Myeloma cell lines as well as primary tumor cells from MM patients constitutively expressed IL-16 RNA and protein and spontaneously secreted soluble IL-16. Functional analyses revealed that IL-16 supports the proliferation of myeloma cells. Accordingly, silencing of IL-16 expression had an anti-proliferative effect on the tumor cells. Most importantly, the application of a monoclonal antibody directed against IL-16had a strong growth-inhibiting influence on myeloma cells. Conclusions:These findings suggest that cytokine IL-16 is an important growth-promoting factor in MM and might represent a novel diagnostic and therapeutic target for this incurable human malignancy. Disclosures:No relevant conflicts of interest to declare.

THE BELGIAN 2010 CONSENSUS RECOMMENDATIONS FOR THE TREATMENT OF MULTIPLE MYELOMA

Since the introduction of novel therapeutic agents including thalidomide, lenalidomide and bortezomib, the prognosis of multiple myeloma (MM) has significantly improved. These agents have been incorporated into numerous treatment schedules for newly diagnosed as well as more advanced MM patients. Hence, the therapeutic options for MM have become more complex and subject to rapid changes. The multiple myeloma study group (MMSG) of the Belgian Hematological Society has established recommendations for the treatment of MM as based on an extensive review of the literature which is also summarized in this paper. The recommendations are the result of a consensus opinion between haematologists with experience in the field and representing most haematology centres in Belgium. Where applicable, reimbursement criteria are also taken into account. The consensus recommendations should be a reference for use by clinical haematologists in daily practice.

Novel Therapeutic Targets for Multiple Myeloma

The past decade has witnessed a dramatic improvement in the therapeutic options in multiple myeloma (MM). Several novel biologically targeted agents are in clinical use and have resulted in improved outcomes. However, the disease remains incurable, underscoring the need for continued efforts towards understanding MM biology, better risk stratification and exploitation of novel therapeutic approaches. Novel agents that target tumor and stromal compartments can be categorized as those that target protein dynamics (e.g., heat shock protein 90 and the ubiquitin-proteasome system), intracellular signaling kinases (e.g., JAK/STAT, PI3k/Akt/mTOR and MAPK pathways), cell cycle molecular machinery (e.g., cyclin-dependent kinase inhibitor and Aurora kinase inhibitors), membrane-bound receptors (e.g., IGF-1, VEGF and CD40), epigenetic modulators (e.g., DNA methyltransferase and histone deacetylase), tumor vasculature and microenvironment (e.g., angiogenesis and integrins) and agents modulating anti-MM immune responses. This article focuses on a series of new therapeutic targets that have shown promising preclinical results and early evidence of anti-MM activity in clinical studies, either alone or in combination with other conventional or novel anti-MM treatments.

Novel therapies in multiple myeloma for newly diagnosed nontransplant candidates.

In the twenty-first century, melphalan-prednisone can no longer be regarded as the standard treatment of multiple myeloma patients not eligible for high-dose melphalan followed by autologous stem cell transplantation. The introduction of thalidomide, lenalidomide, and bortezomib has improved the arsenal of therapeutic options in multiple myeloma. Indeed, randomized studies have shown that melphalan-prednisone-thalidomide and melphalan-prednisone-bortezomib are superior to melphalan-prednisone alone. In addition, other combinations, including lenalidomide, are under study. In this review, we discuss the role of novel therapies in multiple myeloma in elderly multiple myeloma patients. Important aspects, such as toxicity and the role of prognostic factors, are also addressed.

Novel Agents for Relapsed and/or Refractory Multiple Myeloma

The introduction of novel agents, such as thalidomide, bortezomib, and lenalidomide, has altered the landscape of therapeutic options for multiple myeloma by offering new mechanisms for targeting this disease. Combinations of these agents, with each other and/or traditional chemotherapeutics, have vastly increased the treatment options for patients both frontline, and at relapse, providing higher response rates, and importantly, increasing median overall survival. In this review, we will discuss the use of these novel agents and their combinations in patients with relapsed and/or refractory multiple myeloma.

Role of Previous Thalidomide Administration on Final Outcome for 72 Patients with Relapsed Multiple Myeloma (MM) Treated with Bortezomib–Based Therapy

New drugs such as thalidomide, bortezomib and lenalidomide have expanded the therapeutic options for MM while improving outcome in both young and elderly patients. However, the best novel agents sequence in the therapeutic strategy for MM is still not definitely delineated as relapsed MM right after first line thalidomide therapy seems to be more resistant jeopardizing final outcome as per overall survival while still making questionable when to administer it, either at the beginning or later during the course of the disease. We analyzed 72 relapsed MM patients who were enrolled in two salvage study protocols which included bortezomib, dexamethasone and chemotherapy (Offidani et al, ASH 2007 and EHA 2008) and who had been treated with thalidomide first (18 patients) or subsequently (30 patients) or not treated at all with thalidomide (24 patients). We compared these three groups of patients in terms of response rate, post-relapse PFS and post-relapse OS with the aim to assess the role of previous administration of thalidomide on final outcome in this patient population. Median age for the 72 patients was 65 years (range 31–82); ISS stage 2–3 assessed in 51% of patients and unfavourable cytogenetics in 42%. Thirty four patients had been rescued in first relapse, 19 in second and 19 in third or subsequent relapse. Median disease history was 34 months (range 8–173). Forty four patients relapsed after high-dose therapy and autologous stem cell transplantation. The 48 patients were previously treated with thalidomide a median time of 8 months (range 4–48 months). VGPR or better response rate in the groups of patients treated with thalidomide in first line, second or subsequent line or never treated with thalidomide were 44%, 42% (p=0.795) and 79% (p=0.003; p=0.002), respectively.. Multivariate stepwise regression analysis selected only previous thalidomide treatment (OR=1.9; 95%CI=1.5–2.4; p=0.024) as factors affecting response whereas age, previous therapy lines, previous remission duration, previous transplant, previous disease history, sCRP, ISS stage and cytogenetics were not significantly associated to response. In the same groups post-relapse PFS was 9 months, 14 months (p=0.308) and not reached (p=0.018; p=0.055) while post-relapse 2 years OS was 51%, 50% (p=0.564) and 72% (p=0.074; p=0.135). Cox regression analysis showed that the presence of ISS 2–3 (p=0.010), previous thalidomide administration (p=0.052), and response < VGPR (p<0.0001) translated in significantly poorer post-relapse PFS and OS. Stepwise Cox regression analysis selected only response < VGPR as factor significantly associated to poor post-relapse OS (2yrs OS 26% vs 83%; p<0.0001; HR=7.0 95CI=2.6–18.9). In the group of 48 patients previously treated with thalidomide, time on thalidomide (cut-offs 4, 8, 12, 24 months) did not affect post-relapse PFS and OS. These data suggest that, even in relapse, response to salvage therapy is the most powerful predictor of PFS and OS. Unfortunately, previous thalidomide administration, particularly as front-line therapy, apart from time on treatment, significantly decreases VGPR and consequently post-relapse PFS. This lead to a final outcome in terms of OS not different, if worse, in those patients previously treated vs those never treated with thalidomide. These and other data (Barlogie et al NEJM 2006, Palumbo et al, JCO 2008), strongly questioned the use of front-line thalidomide as the best therapeutic strategy for patients with MM since alternatives are now possible.

Advances in the treatment of monoclonal gammopaties: The emerging role of targeted therapy in plasma cell dyscrasias

THE PARADIGM FOR THE TREATMENT OF MONOCLONAL GAMMOPATIES HAS DRAMATICALLY CHANGED: therapeutic options in multiple myeloma (MM) have evolved from the introduction of melphalan and prednisone in the 1960s, high-dose chemotherapy and stem cell transplantation in the late 1980s and 1990s, to the rapid introduction of small novel molecules within the last seven years. Based on the understanding of the complex interaction of the MM cells with the bone marrow microenvironment and the signaling pathways that are dysregulated in this process, a number of novel therapeutic agents are now available. Specifically, three novel agents with a specific-targeted anti-MM activity, have been FDA-approved for the treatment of this disease, namely Bortezomib, thalidomide, and lenalidomide which are now all playing a key role in the treatment of MM. The success of targeted therapy in MM has since led to the development and investigation of more than 30 new compounds in this disease and in other plasma cell dyscrasias such as Waldenström's macroglobulinemia and primary amyloidosis, both in the preclinical settings and as part of clinical trials.

Melphalan-induced DNA damage in vitro as a predictor for clinical outcome in multiple myeloma

As new therapeutic options for multiple myeloma (MM) emerge, identification of biological markers which could predict clinical response to standard treatment with high-dose melphalan (HDM) supported by autologous stem cell transplantation (ASCT) becomes more important. Melphalan-induced damage formation and repair of monoadducts and interstrand cross-links in the p53 gene were studied in peripheral blood mononuclear cells obtained from 32 patients prior to therapy. The same studies were performed in the peripheral blood cells of these patients immediately after subsequent HDM administration. Clinical response and time to progression were correlated with molecular endpoints obtained in vitro. Values for all molecular end-points examined in vitro were highly correlated with the respective in vivo results within individual patients. All in vitro end-points indicative of increased DNA damage and slower repair capacity were predictive of a favorable response to HDM; the area under the curve of total adducts (AUC-TA) had the highest predictive ability. Using the cut-off value of 736 adducts/10(6) nucleotides x h for the AUC-TA, the positive predictive value for clinical response to HDM was 100%. Moreover, patients with an AUC-TA equal to or higher than this cut-off value had significantly longer times to progression than had patients with an AUC-TA lower than the cut-off value (hazard ratio 0.19; 95% confidence intervals 0.06 to 0.60). An in vitro assay to quantify melphalan-induced p53-specific damage formation/repair can be used to select those patients with MM who are more likely to benefit from HDM supported by ASCT.

In vitro expansion of gamma delta T cells with anti‐myeloma cell activity by Phosphostim and IL‐2 in patients with multiple myeloma

T-cell-mediated immunotherapy is a promising therapeutic option for multiple myeloma (MM). Gamma-delta T cells (gammadelta T cells) recognize phosphoantigens and display strong anti-tumour cytotoxicity. The synthetic agonist Phosphostim (bromohydrin pyrophosphate, BrHPP) has been shown to selectively activate Vgamma9Vdelta2 T cells. This study aimed to evaluate the expansion capacity and anti-myeloma cell cytotoxicity of circulating gammadelta T cells from MM patients at different time points throughout the disease, using Phosphostim and interleukin 2 (IL-2). Circulating gammadelta T cell counts in patients with newly diagnosed MM or in relapse did not differ from those in healthy donors. A 14-d culture of peripheral blood mononuclear cells with Phosphostim and IL-2 triggered a 100-fold expansion of gammadelta T cells in 78% of newly diagnosed patients. Gammadelta T cells harvested at the time of haematopoietic progenitor collection or in relapsing patients expanded less efficiently. Expanded gammadelta T cells killed 13/14 myeloma cell lines as well as primary myeloma cells, but not normal CD34 cells. Their killing efficiency was not affected by 2-d IL-2 starvation. This study demonstrated the ability of Phosphostim and IL-2 to expand gammadelta T cells from MM patients, and the efficient and stable killing of human myeloma cells by gd T cells.

Bortezomib (BTZ) prior to and as maintenance therapy after autologous stem cell transplant (ASCT) in multiple myeloma (MM): Long-term follow-up of a phase II study

8044 Background: BTZ and immunomodulatory drugs have emerged as active therapeutic options for MM. However, the optimal method of incorporating these agents in the ASCT paradigm remains unclear. Data is available on thalidomide induction and post ASCT maintenance therapy. However, there are no published data on BTZ used in this manner. Methods: Following induction therapy, BTZ 1.3 mg/m2 was administered on d 1, 4, 8, and 11 q21d × 2 cycles. ASCT with melphalan 200mg/m2 was performed using G-CSF mobilized PBSC. Maintenance BTZ 1.3 mg/m2/d was administered weekly for 4 of 5 weeks × 6 cycles starting 90–120 days post-transplant. Results: 39 patients completed pre-transplant BTZ: 23M/16F, median age 56 years (range 38–69), IgG (28), IgA (10), light chain only (1), Durie-Salmon stage I (1) II (12) III (26), induction anthracycline/thalidomide-based regimen (37). 37 patients underwent ASCT. Pre-transplant treatment with BTZ did not adversely affect stem cell yield or engraftment (Uy et al, Blood, 2005;106(11): abstr 2926). The ORR /CR+VGPR were 92%/53% at d90–120 post-transplant. With a median follow up of 897 days, the median PFS was 806 days and Kaplan-Meier estimate of 3-year PFS is 41% (95% CI, 31–63%). Median OS has not been reached with 3-year OS estimate of 79% (95%CI, 63–94%). 14/39 (36%) patients experienced varicella zoster virus (VZV) reactivation at a median of 200 days post-enrollment. 12/39 patients had grade (Gr) 1 neuropathy at enrollment. Gr 3/4 neuropathy emerged in 2 patients preventing initiation of maintenance BTZ. Gr 3/4 neuropathy emerged in 3 patients during maintenance BTZ requiring drug discontinuation in two and dose reduction in one patient. No grade 3/4 hematologic toxicity was observed during maintenance BTZ. Conclusions: This is the first trial reporting on sequential administration of BTZ prior to and as maintenance therapy post ASCT in MM. Impressive CR/VGPR, PFS and OS were observed and a high rate of VZV reactivation was seen. No significant financial relationships to disclose.