ALBERT

Description: Abstract 2887 Chronic lymphocytic leukemia (CLL) remains incurable despite advances in the biology and treatment of this disease. Current data support the notion that resistance to therapy is promoted by a “protective” tumor microenvironment in which non-leukemia cells produce factors that enhance the resistance of CLL cells to spontaneous or drug-induced apoptosis. One such factor is the chemokine CXCL12, which interacts with its receptor CXCR4 on CLL cells to promote cancer cell survival. To examine the therapeutic potential of blocking CXCL12-CXCR4 interactions, we studied the effect of BMS-936564, a fully human IgG4 anti-CXCR4 antibody, using an in vitro co-culture model of human bone marrow derived stomal-NKter cells – leukemia cell interaction. Such stromal-NKter cells secrete CXCL12 and enhance the resistance of CLL cells to apoptosis in vitro. We observed that primary CLL cells co-cultured with stromal-NKter cells had significantly greater viability than CLL cells cultured alone (20–60% above baseline at 48 hours). Moreover, CLL cells co-cultured with stromal cells had enhanced resistance to drug-induced apoptosis. We found that BMS-936564 antibody at concentrations of 2–200nM could enhance the rate of apoptosis of CLL cells cultured alone or in the presence of stromal cells. CLL cells that expressed unmutated IgVH genes or ZAP-70 appeared equally susceptible to treatment with BMS-936564 as did CLL cells that lack these adverse prognostic markers, as did CLL cells that harbored deletions in 17p13.2 and that were resistant to chemotherapeutic agents, such a fludarabine monophosphate. BMS-936564 antibody inhibited CXCL12 mediated F-Actin polymerization in CLL cells at lower concentrations (20–200nM) compared to AMD-3100 (Mozobil), a small molecule CXCR4 inhibitor (50–150μM). In addition, AMD-3100 did not induce apoptosis in CLL cells (10–300μM). In summary, we observed that the anti-CXCR4 antibody BMS-936564 inhibited CXCL12 mediated activation of the CXCR4 receptor in CLL cells and induced apoptosis in leukemia cells. The pro-apoptotic activity of BMS-936564 was observed in cells cultured alone or together with stromal cells suggesting that this antibody had direct cytotoxic effect on leukemia cells and that it can overcome the protective tumor microenvironment. More over, the activity of BMS-936564 was independent of the presence of poor prognostic factors such as del(17p) suggesting that its mechanism of action is P53 independent. These findings show evidence that the CXCR4-CXCL12 pathway is a valid therapeutic target in CLL and provide additional biological rationale for ongoing clinical trials in CLL and other hematological malignancies using BMS-936564. Disclosures: Kuhne: Bristol-Myers Squibb: Employment. Sabbatini:Bristol-Myers Squibb: Employment. Cohen:Bristol-Myers Squibb: Employment. Shelat:Bristol-Myers Squibb: Employment. Cardarelli:Bristol-Myers Squibb: Employment. Kipps:Abbott: Consultancy, Research Funding.

Description: Background: CXCR4 is a chemokine receptor overexpressed in more than 20 tumor types, including malignant plasma cells. The CXCR4/CXCL12 (SDF-1) axis has been known for many years as a critical regulator of tumor proliferation, cell, as well as migration into and out of the bone marrow. Ulocuplumab (BMS- 936564) is a first in class, fully human IgG4 monoclonal anti-CXCR4 antibody which inhibits the binding of CXCR4 to CXCL12. This study aimed to determine the safety, tolerability, pharmacokinetics, pharmacodynamics, and clinical activity of Ulocuplumab alone and in combination with lenalidomide plus dexamethasone (Len-Dex), or in combination with bortezomib plus dexamethasone (Bor-Dex) in subjects with relapsed/refractory multiple myeloma. Patients / Methods: Patients were eligible for this trial if they were 18 years of age or older with relapsed or relapsed/refractory multiple myeloma after having received at least 2 prior lines of treatment. Patients in whom who both lenalidomide and bortezomib had failed were not excluded from re-treatment with the same regimen. Patients were enrolled at four cancer centers in the U.S. from October 2011 to March 2014. Ulocuplumab (1, 3 and 10 mg/kg) was dose escalated with a 3-plus-3 design with doses of Len-Dex or Bor-Dex to identify maximum tolerated dose (MTD). Ulocuplumab was given weekly in combination with either 25mg lenalidomide on days 1-21 and 40mg oral dexamethasone on days 1, 8, 15, and 22 of the 28-day cycles on Arm A or 1.3 mg/m2 bortezomib on days 1, 4, 8, and 11 and 20mg oral dexamethasone on days 1, 2, 4, 5, 8, 9, 11, and 12 of the 21-day cycles on Arm B since cycle 2. The primary endpoints for this study were dose-limiting toxicities. Other key safety endpoints included incidence of adverse events (AE), AEs leading to discontinuation, SAEs, deaths, and laboratory abnormalities. The efficacy endpoints included overall responses, duration of response, and time to response. Responses were assessed using the IMWG criteria. Results: Forty-six patients were enrolled (median age, 60 years; range, 53-67). The median number of prior therapies was 3 (range, 1-11), with 70.0% of patients having received ≥ 3 lines of treatment. Ulocuplumab was escalated to a maximum of 10 mg/kg without reaching MTD. The most common treatment-related adverse events of any grade were neutropenia (13 patients, 43.3%), diarrhea (10 patients, 33.3%), thrombocytopenia (10 patients, 33.3%), and fatigue (7 patients, 23.3%) in Arm A; and thrombocytopenia (6 patients, 37.5%), fatigue (4 patients, 25.0%) and anemia (4 patients, 25.0%) in Arm B. The overall response rate (≥ partial response) for all subjects in escalation and expansion was 44.4% (20/45). The median time to response was 1.5 months (range 0.4-7.8 months) for Arm A and 1.0 month (range 0.5-3.7 months) for Arm B, respectively. Of note, the combination of Ulocuplumab with Len-Dex showed a high response rate of 55.2% and a clinical benefit rate ( ≥ minimal response) of 72.4%, including patients who have been previously treated with lenalidomide. Conclusion: This study shows that the blockade of the CXCR4-CXCL12 axis by Ulocuplumab is safe and has an encouraging response rate of over 50% in the Len-Dex arm of patients with relapsed/refractory myeloma. The distinct mechanisms of action of this antibody, as well as its non- cross resistance with currently approved approaches, make it a new class of anti-myeloma drug that warrants further exploration and evaluation in future clinical trials. Disclosures Ghobrial: Takeda: Consultancy; Celgene: Consultancy; BMS: Consultancy; Janssen: Consultancy. Richardson:Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees. Anderson:Celgene: Consultancy; Takeda Millennium: Consultancy; Bristol Myers Squibb: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; Oncopep: Equity Ownership; C4 Therapeutics: Equity Ownership. Becker:GlycoMimetics: Research Funding.

Description: Expression of CXCR4 receptor (CD184) has been reported in different malignancies including Chronic Lymphocytic Leukemia (CLL) and the CXCR4-CXCL12 axis has been described to play a very important role in cancer development. Moreover, this pathway can be inhibited using CXCR4 antagonists. Previously, we have shown that BMS-936564, an anti-CXCR4 IgG4 antibody, can block in vitro the CXCR4/CXCL12 pathway in CLL overcoming stromal cell protection by inducing apoptosis, inhibiting F-actin polymerization, and migration of cells. These findings provide the rationale for an ongoing phase I clinical study in which CLL subjects received four weekly infusions of BMS-936564 antibody followed by 5 monthly cycles of bendamustine, rituximab and BMS-936564 antibody (BRB chemoimmunotherapy). Eleven (n=11) subjects with relapse / refractory disease have been enrolled and treated in this study. Here, we present correlative studies performed in three of those CLL subjects with samples collected at different time points (day 1, 2, 8, 15 and 22) during the monotherapy cycle of BMS-936564. All three subjects showed leukocytosis that was detected as early as in 4 hours following the initial BMS-936564 infusion (median increase of 64.6% above base line; range: 59.7% - 112.7%). Leukocytosis was present during the entire four weeks of monotherapy with BMS-936564. Leukocytosis in these three patients was due primarily to increase in absolute counts of CLL cells (Median increase of 129.6%; range: 95.3% - 324.8%). Interestingly, there was no evidence of increase in the absolute number of normal lymphocytes. Only one of the three patients showed an increase in neutrophil counts after infusion of BMS-936564. We observed changes in the level of CXCR4 expression after infusion with BMS-936564. All subjects showed CXCR4 down-regulation in peripheral CLL cells with a median percentage decrease in the level of expression of 106.7% (Range: 25.1% - 350.7%). We did not observe changes in CXCR4 expression in normal B cells. In contrast to our in vitro studies where we observed that all tested CLL samples underwent apoptosis after treatment with BMS-936564, only one subject showed significant increase in the percentage of apoptosis after infusion of BMS-936564 in vivo. The levels of apoptosis detected were relatively low (

Description: Background: CXCR4 is a chemokine receptor over-expressed on 〉 75% of cancers, including myeloid leukemia blasts. Ulocuplumab (BMS- 936564) is a first in class, fully human IgG4 monoclonal antibody which inhibits the binding of CXCR4 to CXCL12, resulting in the mobilization of leukocytes from the bone marrow to the peripheral blood. Ulocuplumab also induces apoptosis of CXCR4+ cells in clinicial samples (i.e., leukemia blasts) and in in vitro experiments (e.g. in Tregs). It is thus hypothesized that Ulocuplumab may induce the mobilization and apoptosis of myeloid blasts & immunosuppressive cells which could improve the overall response rate to chemotherapy Objective: To conduct a first-in-man phase I dose escalation/ expansion trial to determine the safety, pharmacology, and clinical benefit of Ulocuplumab in relapsed/refractory AML Results: Seventy three subjects (median age, 58 yrs; range, 21-79 y) with relapsed/refractory AML were treated with Ulocuplumab and MEC [mitoxantrone, 8 mg/m2; etoposide , 100 mg/m2; and cytarabine, 1 g/ m2; i.v. d 1-5]. Thirty subjects in escalation received a single infusion of Ulocuplumab (doses of 0.3, 1, 3, or 10 mg/kg) one week prior to starting MEC and 3 additional weekly doses per MEC cycle thereafter (starting on Day 1). Ulocuplumab was escalated to a maximum of 10 mg/kg without any dose-limiting toxicity during monotherapy or in combination with MEC in the 1st cycle. In expansion phase, 43 patients were similarly treated with10 mg/kg Ulocuplumab and MEC. The overall complete remission and complete remission with incomplete blood count recovery rate (CR/CRi) was 51%. Subjects with first CR 〉 6 months had better ORR (16/23, 70%) than those with CR1 ≤6 months or primary induction failure (6/20, 30%). Of note, four subjects had CR/CRi after a single dose of Ulocuplumab monotherapy. Transient, mild/moderate thrombocytopenia was the only treatment-related AE documented with Ulocuplumab monotherapy. Only one subject presented a mild infusion reaction on Cycle 1 Day 1. The safety profile in combination with MEC was similar to MEC alone as was the 60 day all-cause mortality (16.3%). A median 2- and 5-fold mobilization of leukocytes and leukemic blasts into the peripheral circulation was reported at day 8, respectively. There was a trend demonstrating that higher CXCR4 expression on AML blasts correlated with a positive clinical response. Reversible and manageable hyperleukoctosis occurred in one subject. Conclusions: This study shows that the blockade of the CXCR4-CXCL12 axis with Ulocuplumab has antileukemic activity and safely improves the historic response rate achieved with MEC alone (i.e.,24-28%). Disclosures Becker: Bristol-Myers Squibb: Research Funding. Off Label Use: Etoposide is indicated in the management of refractory testicular tumors and small cell lung cancer. . Foran:Bristol-Myers Squibb: Research Funding. Altman:Bristol-Myers Squibb: Research Funding. Yacoub:Bristol-Myers Squibb: Research Funding. Castro:Bristol-Myers Squibb: Research Funding. Sabbatini:Bristol-Myers Squibb: Employment. Dilea:Bristol-Myers Squibb: Employment. Wade:Bristol-Myers Squibb: Employment. Xing:Bristol-Myers Squibb: Employment. Gutierrez:Bristol-Myers Squibb: Employment. Cohen:Bristol-Myers Squibb: Employment. Smith:Bristol-Myers Squibb: Research Funding.

Description: Background: CXCR4 is a chemokine receptor over-expressed on 〉 75% of cancers, including malignant plasma cells. Ulocuplumab (BMS- 936564) is a first in class, fully human IgG4 monoclonal anti-CXCR4 antibody which inhibits the binding of CXCR4 to CXCL12. Ulocuplumab induces apoptosis of CXCR4+ multiple myeloma cell lines and has single agent activity in vivo in MM tumor xenograft models. It is thus hypothesized that Ulocuplumab may improve the overall response rate to standard therapy in relapsed-refractory multiple myeloma (rel/ref MM) by distinct mechanisms of action, i.e., mobilization and apoptosis of malignant plasma cells and immune regulation. Objective:This study aimed to determine the safety, tolerability, pharmacokinetics, pharmacodynamics and clinical activity of Ulocuplumab alone and in combination with lenalidomide plus low-dose dexamethasone (Len-Dex), or in combination with bortezomib plus dexamethasone (Bor-Dex) in subjects with rel/ref MM. Methods: Ulocuplumab (i.e., 1, 3 and 10 mg/kg) was dose escalated with a 3-plus-3 design with doses of Len-Dex orBor-Dex to identify MTD. For Cycle 1, Ulocuplumab was administered as monotherapy on Days 1 and 8. Starting on Day 15, Ulocuplumab was administered in combination with lenalidomide [25 mg/d/21 days of a 28 day cycle] plus low dose dexamethasone [40 mg/week] and monitored for incidence of DLT(s) within Cycle 1 (42 Days) of study treatment. For the Bor-Dex group, also starting on Day 15, Ulocuplumab was administered in combination with bortezomib (1.3 mg/m2Days 1, 4, 8, 11 of a 21 day cycle] plus dexamethasone [days 1,2,4,5,8,9,11,12] and monitored for incidence of DLT(s) within Cycle 1 (35 Days) of study treatment. For the expansion phase, subjects received 10mg/kg Ulocuplumab monotherapy on Days 1 and 8 followed by weekly doses in combination with Len-Dex (28-day cycles). Subjects were assessed at day 14 and after every cycle by IMWG criteria. Results: Forty four subjects were evaluated (median age, 59.5 yrs; range, 44-77). The median number of prior therapies was 4, (range, 1-9), with 76% of subjects having received ≥ 3. Subjects had received bortezomib in 93% of the cases, lenalidomide in 86% , thalidomide in 30%, carfilzomib in 20% and pomalidomide in 11%. Thirty subjects in escalation received Ulocuplumab alone and in combination with Len-Dex : One subject in the U-Bor-Dex group experienced a DLT in which there was delayed platelet recovery to ≤ Grade 1 or baseline which resulted in a delay of dosing of ≥ 21 days. Ulocuplumab was escalated to a maximum of 10 mg/kg without reaching MTD in monotherapy or in combination therapy. Twenty one subjects were treated in expansion phase. There were no grade 4 toxicities with Ulocuplumab monotherapy and Grade 3 toxicities with monotherapy included thrombocytopenia (6.5%), anemia (4.3%), respiratory infections (4.3%), femur fracture (4.3%), lymphopenia (2.2%), neutrophil count decreased (2.2%), platelet count decreased (2.2%) and cerebrovascular accident (2.2%). The safety profile of Ulocuplumab with Len-Dex or Bor-Dex was similar to either combination alone. Two subjects (4.5%) presented reversible G2 infusion reactions. The overall response rate (≥ PR) for all subjects in escalation and expansion was 50% (22/44), including 1 CR, 6 VGPR and 15 PR. The ORR by group was 55.1 % (16/29) and 40% (6/15) for U-Len-Dex and U-Bor-Dex, respectively. Furthermore, the ORR in expansion with 10 mg/kg U-Len-Dex was 57% (12/21) with 4 VGPRs and 8 PRs. Eight subjects in this expansion group had at least SD with a mean duration of 159 days (range, 46-437 days), resulting in 95% of subjects with clinical benefit. A median 2-fold mobilization of leukocytes into the peripheral circulation was reported after each infusion of Ulocuplumab at 3 and 10 mg/kg. Samples showed rapid mobilization of leukocytes at 2 hours post-Ulocuplumab with a partial decrease at 3-4 days post-administration without reaching baseline. Mobilization of plasma cells was also documented in some subjects. Conclusions: This study shows that the blockade of the CXCR4-CXCL12 axis by Ulocuplumab is safe and shows a high response rate of over 50% in the Len-dex arm of patients with relapsed/refractory myeloma who have been previously treated with lenalidomide and bortezomib. The distinct mechanisms of action of this antibody make it a new class of anti-myeloma drug that deserves further exploration in clinical trials. Disclosures Ghobrial: Onyx: Advisory board Other; BMS: Advisory board, Advisory board Other, Research Funding; Noxxon: Research Funding; Sanofi: Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Plerixafor is not FDA approved for relapsed myeloma. Anderson:Celgene: Consultancy; Sanofi-Aventis: Consultancy; Onyx: Consultancy; Acetylon: Scientific Founder, Scientific Founder Other; Oncoprep: Scientific Founder Other; Gilead Sciences: Consultancy. Sabbatini:Bristol-Myers Squibb: Employment. Dilea:Bristol-Myers Squibb: Employment. Cardarelli:BMS: Employment. Wade:Bristol-Myers Squibb: Employment. Xing:Bristol-Myers Squibb: Employment. Gutierrez:Bristol-Myers Squibb: Employment. Cohen:BMS: Employment.

Description: Background Bone marrow homing of AML is dependent on CXCR4, and high levels of CXCR4 expression correlate with worse survival in AML (Rombouts et al 2004, Spoo et al 2007). CXCR4 antagonists overcome environment adhesion mediated drug resistance and enhance chemotherapy induced cytotoxicity (Liesveld et al 2007, Zeng et al 2009, Nervi et al 2009, Beider et al 2010). Plerixafor, a small molecular CXCR4 inhibitor, was studied in a phase I trial of newly diagnosed AML patients (Uy et al ASH 2011), and BMS-936564, a fully-human monoclonal antibody to CXCR4, in combination with MEC (mitoxantrone, etoposide, cytarabine), is currently under study in relapsed/refractory AML. Method The clinical trial completed a phase I dose escalation phase in AML patients, with increasing concentrations of BMS-936564 in 4 dose cohorts (0.3,1,3, and 10 mg/kg) and is currently enrolling a cohort of first salvage AML patients at the maximum dose of 10 mg/kg. The initial cohort of patients at 0.3 mg/kg received three weekly doses of antibody on days 1, 8, 15 [monotherapy period of cycle 1 (21 days)], followed by the same dose of antibody on days 1, 8, 15 of cycle 2 plus MEC chemotherapy [days 1-5 of cycle 2, (28 day cycle)]. After enrollment of the first cohort, the protocol was amended to reduce the monotherapy period to 1 week (1 dose of BMS-936564) in cohorts 1, 3, and 10 mg/kg, followed by the same combination regimen. As a companion study to this trial with the anti-CXCR4 antibody, we are investigating CXCR4 expression, timing of mobilization of leukemic blasts and leukemia stem cells (LSCs), and induction of apoptosis. Mobililzation of LSCs will be critical to eradication of leukemia, as they might serve as a reservoir for drug resistance and future relapse. We analyzed serial blast and LSC populations from blood and bone marrow samples from patients undergoing treatment by flow cytometry for phenotype, CXCR4 and annexin V expression. The putative LSCs were defined as CD34+CD38-CD123+ or by aldehyde dehydrogenase. Results An independent assessment of CXCR4 expression in 56 consecutive AML patients from our institution not related to this clinical trial revealed a mean % expression of 31%, range 1-99%, with mean fluorescence intensity (MFI) of 2092, range 319-7942. A sample of 18 patients showed a correlation in CXCR4 expression between gated blasts derived from blood and bone marrow samples from the same patient (For % expression, r2=0.85, p=5e-8; MFI r2=0.45, p=0.002). Our site has enrolled 24 AML patients thus far on the above noted trial of BMS-936564. Administration of BMS-936564 resulted in brisk mobilization of leukemic blasts in 14/24 patients that initially peaked within at 2-6 hours post start of infusion in most patients, with an average of 2.1-fold increase ± 1.8 fold (range 1.06-8.96 fold), and some blasts continued to be in circulation for days. In most cases, the samples for which mobilization was not observed either did not have circulating blasts at baseline, or were from patients who received lower doses of BMS-936564. In addition, CD34+CD38-CD123+LSCs were also mobilized post-treatment with BMS-936564, and in some cases, continued to rise over the subsequent days, during which the blast population declined. The average rise in %CXCR4 was from 29.3% pre-treatment to 69.8% peak value for blasts, and 23.0% pre-treatment to 75.6% peak value for LSCs. Although a direct correlation between CXCR4 expression by blasts and fold mobilization was not apparent, the highest fold increase in mobilization (∼9-fold) did occur in the patient with a moderately high level of CXCR4 expression, 42.5%. In this patient, there was also a sharp decline in circulating CXCR4 positive cells within 2 days and the patient achieved complete remission. BMS-936564 has demonstrated apoptosis in some preclinical models (Kuhne MR et al Clin Cancer Res v19(2): 357-66 (2013)).) For most patients, there was some increase in annexin V staining observed during the first 96 hours after antibody exposure. One patient sample with initial low baseline level of apoptosis exhibited a rise in annexin V staining (from 6% to 48%) that peaked on day 3 after administration of BMS-936564. Conclusion These data demonstrate that BMS-936564 induces mobilization of both AML blasts and LSCs, which may enhance chemotherapy-induced cytotoxicity in relapsed/refractory AML. Disclosures: Chien: Bristol-Myers Squibb: Research Funding. Cardarelli:BMS: Employment. Sabbatini:Bristol-Myers Squibb: Employment. Shelat:Bristol-Myers Squibb: Employment. Cohen:Bristol-Myers Squibb: Employment. Becker:Bristol-Myers Squibb: Research Funding.