ALBERT

Description: Introduction: Romiplostim is a thrombopoietin receptor agonist approved for use in adult pts with ITP. Pooled analyses of combined pt data from romiplostim ITP clinical studies have previously been reported. Here we report updated safety and efficacy data according to baseline splenectomy status. Methods: Data from adult pts in 13 completed ITP studies with romiplostim were analysed up to June 2014. Pts received romiplostim, placebo or medical standard of care (SOC) and data from the placebo/SOC arms were pooled. All 13 studies were included in analyses of baseline pt characteristics and safety endpoints; 4 early dose-finding studies were excluded from analyses of efficacy endpoints as they do not reflect the current dosing of romiplostim. Adverse events were adjusted for time spent on study and reported as rates per 100 pt-years. For pts who started their parent study in the placebo/SOC group and then went on to receive romiplostim in an extension study, all data from the first dose of romiplostim were included in the romiplostim group. A platelet response was defined as a platelet count ≥50x109/L without rescue medication in the previous 8 weeks; a platelet response for 9 out of any 12 consecutive weeks on-study was considered a sustained platelet response. All analyses were descriptive and no statistical testing was performed. Results: Data from 1,111 pts were analysed, 395 splenectomized and 716 nonsplenectomized. The splenectomized and nonsplenectomized groups were similar in age (median 52 vs 53 years) and sex (female 64% vs 60%), but in the splenectomized group median baseline platelet counts were slightly lower (14 vs 19x109/L) and a higher proportion of pts were known to have received 〉3 prior ITP treatments (38% vs 12%) than the nonsplenectomized group. Rates of AEs, serious AEs, fatal AEs, treatment-related AEs, thrombotic events, and hemorrhages were lower in nonsplenectomized than splenectomized pts and were in general lower in romiplostim than placebo/SOC-treated pts in both groups. Bone marrow reticulin occurred in 17 romiplostim-treated pts and one placebo-treated pt, at a slightly increased rate in splenectomized vs nonsplenectomized pts. Bone marrow collagen was reported in one romiplostim-treated nonsplenectomised pt. Data from 1,024 pts were analysed for efficacy (376 splenectomized, 648 nonsplenectomized). The median (Q1, Q3) most frequent weekly dose was 4 µg/kg (2, 9) in splenectomized and 3 µg/kg (2, 7) in nonsplenectomized pts. A platelet response was achieved in 82% of splenectomized and 91% of nonsplenectomized pts and a sustained platelet response in 66% and 79%, respectively. The median time to first response was 2.1 weeks for splenectomized and 2.0 weeks for nonsplenectomized pts. Platelet responses were maintained in those who responded: after the first response the median (Q1, Q3) proportion of time with a response was 97% (79%, 100%) for splenectomized and 100% (91%, 100%) for nonsplenectomized pts. Conclusions: A relatively large number of nonsplenectomized pts have received romiplostim in clinical studies. Safety of romiplostim was comparable in splenectomized and nonsplenectomized patients with no new safety signals observed, and platelet response rates were high and of sustained duration in both groups. Abstract 4199. Table Number of events (rate per 100 pt-years) Splenectomized Nonsplenectomized Placebo/SOC N=27 Pt-yr=11.2 Romiplostim N=391 Pt-yr=702.0 Placebo/SOC N=106 Pt-yr=97.7 Romiplostim N=655 Pt-yr=1129.7 All AE 208 (1861.1) 8609 (1226.3) 1028 (1052.6) 9624 (851.9) Serious AE 15 (134.2) 478 (68.1) 92 (94.2) 498 (44.1) Fatal AE 3 (26.8) 11 (1.6) 5 (5.1) 31 (2.7) Treatment-related AE 15 (134.2) 864 (123.1) 152 (155.6) 928 (82.1) Treatment-related serious AE 0 (0) 65 (9.3) 18 (18.4) 59 (5.2) Treatment-related fatal AE 0 (0) 2 (0.3) 0 (0) 3 (0.3) Thrombotic events 1 (8.9) 44 (6.3) 5 (5.1) 52 (4.6) Hemorrhage events 54 (483.2) 1868 (266.1) 233 (238.6) 1591 (140.8) Fatal hemorrhage events 1 (3.7) 0 (0) 0 (0) 5 (0.8) Bone marrow reticulin /collagen events* 1 (8.9) 11 (2.0) 0 (0) 7 (0.8) Hematologic malignancies/MDS 0 (0) 6 (0.9) 4 (4.1) 8 (0.7) Any malignancies 0 (0) 24 (3.4) 9 (9.2) 43 (3.8) * Bone marrow collagen reported in one romiplostim-treated nonsplenectomized pt. Excludes study NCT00907478 as bone marrow evaluations were collected differently than in other studies; in the romiplostim arms the N/pt-yrs were 331/560.6 for splenectomised and 546/866.7 for nonsplenectomised pts. Disclosures Rodeghiero: GSK: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Suppremol: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Steurer:Amgen: Honoraria. Godeau:Amgen: Consultancy. Carpenter:Amgen: Employment, Equity Ownership. Kreuzbauer:Amgen: Employment, Equity Ownership.

Description: Background Olaptesed pegol (NOX-A12) is a novel, potent, L-stereoisomer RNA aptamer that binds and neutralizes CXCL12/SDF-1, a chemokine which attracts and activates immune- and non-immune cells via interaction with the receptors CXCR4 and CXCR7. Signaling of CXCL12 is pivotal to the interactions of leukemic cells with bone marrow microenvironment. The therapeutic concept of olaptesed is to inhibit such tumor-supporting pathways and thereby mobilizing and sensitizing CLL cells to therapy. Here we aim to assess the activity and safety of olaptesed in combination with bendamustine and rituximab (BR) in patients with relapsed / refractory CLL. Methods Twenty-eight relapsed or refractory CLL patients were enrolled and treated in this open-label, single-arm Phase IIa study. To investigate PK/PD, a pilot dose of 1 to 4 mg/kg olaptesed alone was administered to 3 patients per dose group (plus one additional replacement pt) before start of the regular treatment regimen (pilot group). Patients were treated using a dose titration design with intravenous (IV) olaptesed at doses increasing from 1 mg/kg to 2 mg/kg and 4 mg/kg at cycles 1, 2 and 3, respectively, at 1 hour before rituximab treatment. During cycles 4 to 6, olaptesed was dosed at the highest individually titrated dose. Rituximab was administered IV at doses of 375 mg/m² on day 1 of the 1st28-day cycle and 500 mg/m² on day 1 of subsequent cycles. Bendamustine (70 - 100 mg/m²) was given IV on days 2-3 (cycle 1) or days 1-2 (cycles 2-6) of each 28-day cycle following administration of rituximab. Clinical response was assessed according to NCI-WG Guidelines (Hallek M et al. Blood 111; 2008: 5446-56). Results To date, 24 patients completed treatment (12 women, 12 men) with a median age of 68.5 years (range 52 to 79). At screening 5, 9 and 10 patients presented with Binet stage A, B and C, respectively. The median number of prior treatment lines was 1 (range 1-2). Seven high-risk patients presented an unfavorable disease state being relapsed within 24 months after fludarabine/bendamustine treatment (5 pts) and/or presenting a deletion/mutation of the TP53 gene (3 pts). Most patients (19 of 24) were previously treated with fludarabine or bendamustine. A flow cytometric analysis of CD19+/CD5+CLL cells showed a rapid mobilization into the peripheral blood by a single dose of olaptesed which lasted throughout the observational time of 72h. Interestingly, CXCR4 expression levels increased on CLL cell surface in the periphery after olaptesed treatment. This increase, which peaked at 24h, likely reflects the extended circulation of CLL cells in the periphery due to the sustained blockade of CXCL12 by olaptesed. Reduction of lymphadenopathy by ≥ 50% was achieved in 14 out of 21 evaluable patients with reported enlarged lymph nodes by the end of treatment. Concomitantly, rapid reduction of lymphocytosis in peripheral blood with normalization by treatment cycle 2 – 3 was observed and the CLL to leukocyte ratio significantly improved. Efficacy was assessed at the end of cycles 3 and 6. In the full-analysis-set, which excludes two non-evaluable patients (drop-out after the 1st cycle due to adverse events), the overall response rate was 96%: Three patients (14%) achieved a complete response at end of cycle 6 (2 confirmed, 1 investigator reported) and eighteen patients (82%) achieved a partial response (fifteen at end of cycle 6 and three at end of cycle 3). Notably, all seven high-risk patients (defined as relapsed within 24 months after fludarabine/bendamustine treatment and/or presenting a deletion/mutation of the TP53 gene) responded to treatment with olaptesed + BR with a partial response. One patient had a progressive disease. Olaptesed at 1, 2 and 4 mg/kg at a single dose and in combination with BR was safe and well tolerated. The observed adverse reactions were qualitatively and quantitatively as expected for patients treated with BR. Conclusion Olaptesed in combination with BR was safe and well tolerated. Compared with historical data, olaptesed showed superiority over baseline therapy with regards to overall response rate and increasing rates of complete remission, warranting further development of this Spiegelmer in CLL. Disclosures Montillo: Janssen: Honoraria. Kruschinski:NOXXON Pharma AG: Employment. Dümmler:NOXXON Pharma AG: Employment. Riecke:NOXXON Pharma AG: Employment.

Description: CD38 expression of tumor cells has been identified as an important prognostic factor in B-cell chronic lymphocytic leukemia (B-CLL). Although CD38 is involved in effector functions of T cells, the prognostic value of CD38+ T cells has not yet been addressed in B-CLL. In the present study, CD38-expression levels in B-CLL cells and T cells from 204 patients were analyzed by flow cytometry and correlated with clinical and molecular risk parameters. CD38 expression significantly differed in the neoplastic clone from patients with low versus advanced stage, irrespective of the sex of patients. In contrast, CD38 expression was generally higher in T cells from female compared with male patients but only increased in male patients in a stage-dependent manner. In male patients, combined analysis of CD38 in T cells and B-CLL cells identified 4 subgroups with significantly different treatment-free survival. Multivariate analysis including Rai stage and molecular risk parameters of the neoplastic clone identified CD38-expression levels in T cells as an independent prognostic factor in male patients. Combined analysis of CD38 in B-CLL and T cells is superior in predicting outcome of male B-CLL patients than either parameter alone. Further studies are needed to elucidate the underlying mechanisms of the sex-specific role of CD38+ T cells in B-CLL.

Description: Abstract 3316 Background: ITP is characterized by platelet counts

Description: Abstract 3279 Background: ITP is an autoimmune disorder characterized by increased platelet destruction and suboptimal platelet production. Romiplostim stimulates platelet production via the TPO-receptor, and is recommended for second- and third-line treatment of chronic ITP in adults. We report final data from a large prospective study of romiplostim in adults with ITP of varying duration and severity. Methods: Eligibility criteria were broad: patients ≥18 years of age, who had received prior ITP therapies (final protocol amendment: ≥1, previous amendments: ≥3), with low platelet counts (final amendment: ≤ 30 × 109/L, previous amendments: ≤ 10, ≤ 20 × 109/L) or experiencing uncontrolled bleeding. The only excluded comorbidities were: hematological malignancy, myeloproliferative neoplasms, MDS and bone marrow stem cell disorder. Romiplostim was initiated at 1 (final amendment) or 3 (previous amendments) μg/kg/week, with dose adjustments allowed to maintain platelet counts ≥50 × 109/L. Patients could continue on study until they had access to commercially available romiplostim. Rescue medications were allowed at any time; concurrent ITP therapies could be reduced when platelet counts were 〉 50 × 109/L. Primary endpoint was incidence of adverse events (AEs) and antibody formation. Secondary endpoint was platelet response, defined as either (1) doubling of baseline count and ≥ 50 × 109/L or (2) ≥20 × 109/L increase from baseline. Results: A total of 407 patients received romiplostim, 60% of whom were female. Median (Q1, Q3) time since ITP diagnosis was 4.25 (1.20, 11.40) years (maximum 57.1 years), with 51% of patients splenectomised and 39% receiving baseline concurrent ITP therapies. Seventy-one percent of patients completed the study, with requirement for alternative therapy and withdrawn consent the most common reasons for discontinuation (5% each). Median (Q1, Q3) on-study treatment duration was 44.29 (20.43, 65.86) weeks (maximum 201 weeks), with a total of 20,201 subject-weeks on study. Incidence and type of AEs were consistent with previous studies. The most common serious treatment-related AEs were cerebrovascular accident, headache, bone marrow reticulin fibrosis (with no evidence of positive trichrome staining for collagen and no evidence suggesting primary idiopathic myelofibrosis), nausea, deep vein thrombosis, hemorrhage and pulmonary embolism, with each reported in 2 of 407 (0.5%) patients. All other serious treatment-related AEs were each reported in one patient. Eighteen patients died; 3 deaths (hemolysis, intestinal ischaema, aplastic anemia) were considered treatment-related. No neutralizing antibodies to romiplostim or TPO were reported. Approximately 90% of patients achieved each of the platelet response definitions, regardless of splenectomy status. Overall, median (Q1, Q3) time to response was 2 (1, 4) weeks for response definition 1, and 1 (1, 3) week for response definition 2. Median (Q1, Q3) baseline platelet count was 14 (8, 21) × 109/L. After 1 week of treatment median (Q1, Q3) platelet count had increased to 42 (18, 101) × 109/L. From week 8 onwards, and excluding counts within 8 weeks of rescue medication use, median platelet counts were consistently above 100 × 109/L (range 101.0–269.5 × 109/L). Median (Q1, Q3) average weekly romiplostim dose was 3.62 (1.99, 6.08) μg/kg. Summary/conclusions: This is the largest prospective study in adult ITP reported to date. The data reported here are similar to those reported for previous romiplostim studies, with romiplostim able to safely induce a rapid platelet response in adult ITP patients with low platelet counts or bleeding symptoms. Romiplostim is an important, well-tolerated, treatment option for adult ITP patients, which significantly increases and maintains platelet counts. Adverse Event Subject Incidence Platelet Response Disclosures: Janssens: Amgen: Consultancy; Roche: Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees. Tarantino:Cangene corporation: Research Funding; Baxter: Research Funding; Talecris: Honoraria, Speakers Bureau; Up-to-date: Patents & Royalties; The Bleeding and Clotting Disorders Institute: Board Member. Bird:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees. Boccia:Amgen: Equity Ownership, Honoraria, Speakers Bureau. Lopez-Fernandez:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kozak:Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Steurer:Amgen: Honoraria. Dillingham:Amgen Limited: Employment, Equity Ownership. Lizambri:Amgen: Employment, Equity Ownership.

Description: Activating mutations of the BRAF kinase (BRAF V600E) are found in virtually all cases of classical hairy-cell leukemia (HCL), suggesting disease-specific oncogene dependence. Case reports and early trial data demonstrate impressive activity of BRAF inhibitors, but optimal dosing and treatment duration remain unclear. Methods: We report on 21 patients with hairy cell leukemia across Europe (Heidelberg, Innsbruck, Nice, Munich, Cambridge, Erfurt, Freiburg, Luzern, Cologne, Leicester, London) treated with vemurafenib, a specific BRAF inhibitor outside of trials from 2011-2014. Centers provided clinical data and pathology specimen where available. Results: Presence of the BRAFV600E mutation was demonstrated in all patients. Median age of all patients included in this study was 64 (range 45-89) years. Patients received a median of 3 (range 0 to 12) prior treatment lines. Two patients were treated upfront (age, comorbidity). Median time between initial diagnosis and experimental treatment with vemurafenib was 8 (range 0-31) years. Vemurafenib was started at a dose of 240 mg bid in 18 patients and was continued at this dose in 14 patients. In four patients doses were escalated to 720 mg (n=1) and 960 mg (n=3), respectively. Three patients received 480 mg (n=2) bid or 960 mg (n=1) bid upfront. Median therapy duration was 90 (range 55-167) days, and 2 patients are still on therapy (day 85 and 275) at last follow up. All patient's blood counts improved meeting response criteria (Hb 〉 12g/dl, platelets 100.000/ µl, neutrophils 〉1000µl), except for a 89-year-old patient who did not improve with his hemoglobin due to renal anemia. Median time to neutrophil recovery (〉1000/ µl) was 39 (range 9-126) days, to platelet recovery (〉100.000 µl) 28 (range: 10-105) days and time to improvement of anemia (Hb 〉 12 g/dl) 67 (range: 10-105) days, respectively. Seven patients achieved a CR and 13 a PR. Patients who received more than 240 mg bid (n=8) did not have significant more CRs than patients who received 240 mg (n=14) (Fishers test p=0.16). CR did not translate into better EFS (HR 1.2, p=0.7, Figure 1). Immune histology staining was performed to assess p-ERK signaling. Median observation time was 12 months (range: 3-31 months) and median event free survival (retreatment or death) was 17 months for all patients (Figure 1). Survival at 12 months was 87%. Three of 21 patients died; one patient due to HCL disease progression after termination of vemurafenib, one patient developed an AML M6 and one patient died at the age of 89 years due to pneumonia off treatment in remission. Seven patients (28%) including the 2 patients treated upfront were retreated at relapse after a median of 10 months (range: 4-16 months) after stopping vemurafenib. Six patients were reexposed to vemurafenib and one received cladribine. All patients responded again to vemurafenib and two patients continue to receive ongoing treatment at 240mg bid and 480mg bid respectively, 18 months and 8.5 months from restarting therapy. Conclusion: Targeting a BRAF V600E can provide disease control in HCL. CR was achieved in 30% of patients and can be achieved with 240 mg bid. Relatively short EFS suggests that treatment duration and dosing regimen should be optimized and combination treatments involving BRAF inhibitors should be explored in refractory HCL patients. Moreover, dosing schedules and treatment duration may need to be individualized in patients with HCL carefully taking into account individual pharmacodynamics and response. Figure 1: EFS (re-treatment or death) of HCL patients after vemurafenib treatment. Patients with CR (solid line) and patients with PR (dashed line) have similar EFS. Figure 1:. EFS (re-treatment or death) of HCL patients after vemurafenib treatment. Patients with CR (solid line) and patients with PR (dashed line) have similar EFS. Disclosures Herold: Roche Pharma AG/Germany: Honoraria, Research Funding. Dearden:Roche, GSK, Gilead, Janssen, Napp: Honoraria.

Description: Introduction: Chemoimmunotherapy has become a standard approach in previously untreated and also in pretreated CLL. Addition of Rituximab to FC in fit patients has proven superior to chemotherapy alone and more recently aCD20 treatment was shown to improve outcomes in patients treated with Chlorambucil, suggesting that immunotherapy may be of benefit, independent of the chosen chemotherapy backbone. In follicular and mantle cell lymphoma rituximab maintenance treatment has become a clinical standard. While we and others have presented Phase II data on the feasibility of Rituximab maintenance after chemoimmunotherapy induction, there are currently no available randomized data on the efficacy of such an approach. Study design: Patients were recruited after informed consent at the end of any Rituximab-containing induction treatment in 1st or 2nd line that achieved at least a PR. Excluded were patients with uncontrolled bacterial or viral infections and conditions that might severely affect life-expectancy (such as other malignancy, heart disease etc). The trial was registered at clinicaltrials.gov with the identifier NCT01118234. Randomization was stratified by country, line of treatment, induction response and type of induction regimen. Primary endpoint was PFS and a planned sample-size of 256 patients was calculated. All patients were recruited in participating centers between September 2009 and December 2013. An interim analysis was planned to be conducted after half of the planned events (i.e. 46) were observed and is presented here. Results: The current analysis includes 263 patients enrolled into the trial. Patients had a median age of 63 years, 28.9% were female and 80.6% were enrolled after 1st induction treatment. Hierarchical FISH cytogenetic risk was available in 221 patients: del17p 3.1%, del11q 27.6%, tris 12 10.8%, del13q 36.2%, and normal FISH karyotype 21.2%. IgVH Mutation state was available in 161 patients at time of interim analysis and 67% were unmutated. The induction regimen was FCR in 73.5% and BR in 20.2%, the response to induction treatment was CR/CRi in 58% and PR in 41.8% of patients and 57% scored negative in an 8-colour MRD flowcytometric analysis after induction. Rituximab treatment was allocated to 134 patients and 129 were in the observation arm. No significant imbalances in randomization were found in the above-mentioned parameters. Median observation time is currently 17.3 months. Regarding toxicities the current state of monitoring allows an analysis on the level of SAEs only. SAE causes were well balanced between arms with the exception of infectious SAEs - 32 in the rituximab and 22 in the observation arm, 3 deaths were attributed to infections (1 in the rituximab arm and 2 in the observation arm) - and secondary malignancies (8 in the rituximab arm vs. 1 in the observation arm). Four of the neoplasms in the rituximab arm were localized non-melanoma skin cancers and the 2 deaths from malignomas occurred one in each arm. Regarding efficacy, currently 27.9% have progressed in the observation arm and 14.9% in the rituximab arm. Ten patients died in the observation arm and 7 in the rituximab arm. The primary endpoint (PFS) is significantly in favour of rituximab maintenance (see Fig) with a p-value of 0.007 and a PFS at 17.3 months of 85.1% vs.75.5% in rituximab vs. observation arms, respectively. To account for toxicities and secondary neoplasms an EFS was calculated counting secondary malignancies, termination of treatment due to toxicities, progression or death as events. In this analysis the benefit was preserved, albeit with a lower p-value of 0.03. The observed benefit seemed independent from response after induction (CR vs. PR), but associated with positive MRD state after induction. Further factors that influenced the benefit in exploratory subgroup analyses were sex, cytogenetics, IgVH and B-symptoms at diagnosis. Conclusions: Rituximab maintenance after chemoimmunotherapy induction in CLL seems feasible, although with an increase in infectious complications, and shows signs of efficacy in this interim analysis. The presented interim analysis refutes the alternative hypothesis and allows the trial to continue. Exploratory analyses suggest that with longer follow-up it may be possible to define subpopulations with larger benefit from extended immunotherapy. Figure: PFS by treatment arm (Observation arm: ; Rituximab arm: __) Figure:. PFS by treatment arm (Observation arm: ; Rituximab arm: __) Disclosures Greil: Roche: Honoraria; Pfizer: Honoraria, Research Funding; Boehringer-Ingelheim: Honoraria; Astra-Zeneca: Honoraria; Novartis: Honoraria; Genentech: Honoraria, Research Funding; Janssen-Cilag: Honoraria; Merck: Honoraria; Mundipharma: Honoraria, Research Funding; Eisai: Honoraria; Amgen: Honoraria, Research Funding; Celgene: Consultancy, Research Funding; Cephalon: Consultancy, Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria; Sanofi Aventis: Honoraria; GSK: Research Funding; Ratiopharm: Research Funding. Off Label Use: Rituximab in Maintenace Treatment of CLL. Kozak:Roche: Honoraria, Travel grants Other. Girschikofsky:Pfizer: Honoraria, Research Funding; Mundipharm: Consultancy, Honoraria. Petzer:Celgene: Honoraria, unrestricted grant Other. Egle:Roche: Honoraria, Research Funding, Travel Grants Other.

Description: Background NOX-A12 is a novel, potent, L-stereoisomer RNA aptamer (Spiegelmer(®)) that binds and neutralizes CXCL12/SDF-1, a chemokine which attracts and activates immune- and non-immune cells via interaction with its receptors, CXCR4 and CXCR7. The signaling of CXCL12 has been shown to play an important role in the pathophysiology of chronic lymphocytic leukemia (CLL), especially in the interaction of leukemic cells with tissue microenvironment. The therapeutic concept of NOX-A12 is to mobilize these bone marrow- and tissue-resident CLL cells into the blood, thereby removing CLL cells from the nurturing milieu and sensitizing them to cytotoxic drugs such as bendamustine and rituximab (BR). Methods To date, 19/33 planned patients have been enrolled into a multicenter Phase IIa study of NOX-A12 alone and in combination with BR in relapsed CLL patients. Here we report interim data on PK, PD and preliminary efficacy of a pilot group consisting of 3 cohorts of 3 patients each. In the pilot phase, cohorts received single doses of 1, 2 or 4 mg/kg NOX-A12 alone, respectively, two weeks prior to 6 cycles of combined treatment of NOX-A12 with BR repeated every 28 days. During combination therapy, NOX-A12 was administered 1-2 hours prior to rituximab following a dose titration design for all patients: NOX-A12 doses were increased from 1 mg/kg to 2 mg/kg and 4mg/kg at cycles 1, 2 and 3, respectively. During cycles 4-6, doses of NOX-A12 were kept at the highest individually titrated dose. Bendamustine (70 - 100 mg/m², according to SPC) was given on day 2 and 3 (cycle 1) or 1 and 2 (cycle 2-6), combined with 375 mg/m2 rituximab on day 1 for the first cycle and 500 mg/m2 for subsequent cycles. Tumor response was assessed according to NCI-WG 1996 criteria (updated by iwCLL 2008). Results In total, 10 patients were enrolled in the pilot group (one additional patient was enrolled due to one patients' under dosing). The median age was 69 years (range 57-77) with 8 women and 2 men being included. Median prior therapies were 2 (range 1-2), whereby all patients were bendamustine naïve and 6 patients had received rituximab treatment prior to enrolment. 2, 4 and 4 patients presented at screening with Binet stage A, B, and C, respectively. 8 patients showed at least 1 cytogenetic aberration at the beginning of treatment. Tumor assessments before enrolment and at end of cycles 3 and 6 were evaluated. Plasma profiles of NOX-A12 in the patient population of the pilot group (Figure 1) were similar to those of healthy volunteers in which a plasma half-life of approximately 38 h was observed. After single doses of NOX-A12, the exposure was dose-linear with peak plasma concentrations of 1.7, 3.5, and 6.7 µM in the corresponding cohorts. CLL cells in the peripheral blood were found to be increased throughout the observational period of 3 days (Figure 2). In all patients presenting with lymphadenopathy, the lymph node size decreased markedly. NOX-A12 as single agent was safe and very well tolerated. All patients responded to the combination treatment of NOX-A12 and BR (ORR 100%); one patient had to be withdrawn from treatment due to multiple infections during cycle 4 having achieved a partial response (PR). At the end of cycle 6, seven patients (78%) showed a PR and two patients (22%) achieved a complete remission (CR). In combination with BR, NOX-A12 was equally safe and well tolerated. Conclusions Proof of principle was achieved as single doses of NOX-A12 reached the expected plasma exposure which translated into an effective and prolonged mobilization of CLL cells into the peripheral blood. In addition, the 100% ORR and 22% CR as well as the virtual absence of additional toxicity on top of BR observed in this pilot group compares very favorably with historical controls. Provided that this promising clinical picture will be maintained in the total sample of 33 patients, further development of this novel anti-CXCL12/SDF-1 Spiegelmer(®) seems warranted. Disclosures: Montillo: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dümmler:NOXXON Pharma AG: Employment. Zöllner:NOXXON Pharma AG: Employment. Zeitler:NOXXON Pharma AG: Employment. Riecke:NOXXON Pharma AG: Employment. Kruschinski:NOXXON Pharma AG: Employment.

Description: Abstract 4805 Anti-angiogenic effects of the proteasome inhibitor bortezomib were analyzed on tumor xenografts in vivo. Bortezomib strongly inhibited angiogenesis and vascularization in the chicken chorioallantoic membrane (CAM). Bortezomib's inhibitory effects on CAM vascularization were abrogated in the presence of distinct tumor xenografts thanks to a soluble factor secreted by tumor cells. Through size-exclusion and ion-exchange chromatography as well as mass spectroscopy we identified GRP-78, a chaperone protein of the unfolded protein response, as being responsible for bortezomib resistance. In fact, a variety of bortezomib-resistant solid tumor cell lines (PC-3, HRT-18), but not myeloma cell lines (U266, OPM-2), were able to secrete high amounts of GRP-78. Recombinant GRP-78 conferred bortezomib resistance to endothelial cells and OPM-2 myeloma cells. Knockdown of GRP78 gene expression in tumor cells and immunodepletion of GRP78 protein from tumor cell supernatants restored bortezomib sensitivity. GRP-78 did not bind or complex bortezomib, but induced prosurvival signals by phosphorylation of ERK and inhibited p53-mediated expression of pro-apoptotic Bok and Noxa proteins in endothelial cells. From our data we conclude that distinct solid tumor cells are able to secrete GRP-78 into the tumor microenvironment, thus demonstrating a hitherto unknown mechanism of resistance to bortezomib. Disclosures: No relevant conflicts of interest to declare.