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Purpose This drug–drug interaction study determined whether the metabolism and distribution of the Polo-like kinase 1 inhibitor, volasertib, is affected by co-administration of the P-glycoprotein and cytochrome P-450 3A4 inhibitor, itraconazole. Methods This was an uncontrolled, open-label, fixed-sequence trial of two 21-day treatment cycles in patients with various solid tumors. In cycle 1 (test), eligible patients were administered volasertib (day 1) plus itraconazole (days −3 to 15). In cycle 2 (reference), patients received volasertib monotherapy. The primary end point was the influence of co-administration of itraconazole on the pharmacokinetic profile (AUC0–tz; Cmax) of volasertib and its main metabolite, CD 10899, compared with that of volasertib monotherapy. Other end points included tolerability and preliminary therapeutic efficacy. Findings Concurrent administration of itraconazole resulted in a slight reduction in the AUC0–tz (geometric mean ratio, 93.6%; 90% CI, 82.1%–106.8%) and a 20% reduction in Cmax (geometric mean ratio, 79.4%; 90% CI, 64.9%–97.1%) of volasertib compared with monotherapy. Of note, concurrent administration of itraconazole + volasertib had no effect on the AUC0–∞ of volasertib. More patients reported at least one drug-related adverse event in cycle 1 than in cycle 2 (75% vs 71%). The most commonly reported drug-related adverse events (cycles 1 and 2) were thrombocytopenia (68% and 33%, respectively), leukopenia (50% and 46%), and anemia (36% and 33%). No objective responses were observed. Stable disease was observed in 25 of 28 patients (89%). Implications While there was no clear evidence of a pharmacokinetic interaction between volasertib and itraconazole, co-administration reduced the tolerability of volasertib. Clinicaltrials.gov identifier: NCT01772563.

Volasertib is a selective cell cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Polo-like kinase (Plk). A potential for prolonged QT intervals was indicated with volasertib in preclinical studies and preliminary clinical data. As a result, electrocardiograms (ECGs) have been collected in all volasertib clinical trials to monitor potential cardiac effects. This article describes strategic and statistical methods prospectively planned to perform an integrated analysis of ECG data from available trials to evaluate volasertib’s effect on cardiac repolarization, as reflected by changes in the duration of QT interval and other ECG-related endpoints. Methods to effectively cope with heterogeneity between trials (ie, differences in study designs) are discussed. These strategies may be useful for other investigational drugs for which QT risk assessment is required, but a thorough QT/QTc trial is not feasible, resulting in the need for an alternative approach. Volasertib therapy relevantly prolonged adjusted mean QTcF change from administration baseline following the first and subsequent infusions. The integrated analysis revealed that the volasertib effects on the mean QTc changes from baseline were transient and had resolved at 24 hours after start of the first infusion. There was no evidence for a long-term impact on the QTcF interval following multiple infusions with volasertib.

Treatment outcomes for older patients with acute myeloid leukemia (AML) have remained dismal. This randomized, phase 2 trial in AML patients not considered suitable for intensive induction therapy compared low-dose cytarabine (LDAC) with or without volasertib, a highly potent and selective inhibitor of polo-like kinases. Eighty-seven patients (median age 75 years) received LDAC 20 mg twice daily subcutaneously days 1-10 or LDAC + volasertib 350 mg IV days 1 + 15 every 4 weeks. Response rate (complete remission and complete remission with incomplete blood count recovery) was higher for LDAC + volasertib vs LDAC (31.0% vs 13.3%; odds ratio, 2.91; P = .052). Responses in the LDAC + volasertib arm were observed across all genetic groups, including 5 of 14 patients with adverse cytogenetics. Median event-free survival was significantly prolonged by LDAC + volasertib compared with LDAC (5.6 vs 2.3 months; hazard ratio, 0.57; 95% confidence interval, 0.35-0.92; P = .021); median overall survival was 8.0 vs 5.2 months, respectively (hazard ratio, 0.63; 95% confidence interval, 0.40-1.00; P = .047). LDAC + volasertib led to an increased frequency of adverse events that was most pronounced for neutropenic fever/infections and gastrointestinal events; there was no increase in the death rate at days 60 + 90. This study was registered at www.clinicaltrials.gov as #NCT00804856.

BACKGROUND Polo-like kinases (Plks) control multiple steps during the cell cycle, and Plk1 is overexpressed in urothelial cancer (UC). Volasertib (BI 6727), a Plk inhibitor, has demonstrated antitumor activity in several malignancies, including UC. In this phase 2 trial, the authors investigated volasertib as a second-line treatment in advanced/metastatic UC. METHODS Patients who progressed within 2 years of 1 prior chemotherapy regimen received 300 mg volasertib on day 1 every 3 weeks. The dose was escalated to 350 mg in cycle 2 if volasertib was tolerated in cycle 1. The primary endpoint was tumor response, which was assessed every 6 weeks; secondary endpoints were progression-free survival, overall survival, duration of response, safety, and pharmacokinetics. RESULTS Fifty patients were enrolled, and the median patient age was 68.5 years (range, 52-83 years). All patients had received prior platinum, 94% of patients had relapsed ≤2 years after prior therapy, 36% had liver metastases, and 54% had lung metastases. The median number of treatment cycles was 2 (range, 1-27 treatment cycles), and 23 patients were dose escalated at cycle 2. Seven patients (14%) had a partial response, 13 (26%) had stable disease, and 30 (60%) progressed within 6 weeks. The median response duration was 41 weeks (range, 29.1-77.3 weeks). The median progression-free survival was 1.4 months, and the median overall survival was 8.5 months. The most frequent grade 3 and 4 adverse events were neutropenia (28%), thrombocytopenia (20%), and anemia (16%). No cumulative toxicity was observed. CONCLUSIONS Volasertib as second-line treatment for advanced/metastatic UC had an acceptable safety profile but demonstrated insufficient antitumor activity for further evaluation as a monotherapy. Cancer 2014;120:976–982. © 2013 American Cancer Society.

Objectives This phase II, open-label study was designed to evaluate the response rate to the polo-like kinase 1 (Plk-1) inhibitor BI 2536 in patients with sensitive-relapsed small cell lung cancer (SCLC). Secondary endpoints included progression-free survival (PFS), overall survival (OS), duration of response, and safety. Materials and methods Patients were treated with the recommended phase II dose of 200 mg of BI 2536 intravenously every 21 days. This was a two-stage design with an early stopping rule in place if responses were not seen in at least 2 of the first 18 enrolled patients. Results and conclusion Twenty-three patients were enrolled in the study and 21 patients were evaluable for response. No responses were observed and all 23 patients have progressed. The median PFS was 1.4 months. Treatment was generally well tolerated and the most frequent adverse events were neutropenia, fatigue, nausea, vomiting, and constipation. BI 2536 is not effective in the treatment of sensitive relapsed SCLC. The criteria for expanding the trial to the second stage were not achieved, and the study was terminated for a lack of efficacy.

Polo-like kinase 1 (Plk1) is expressed during mitosis and overexpressed in multiple cancers, including non-Hodgkin lymphoma (NHL). This phase I study determined the maximum tolerated dose (MTD) of BI 2536, a Plk1 inhibitor, as a 1 h infusion once every 3 weeks in post-transplant relapsed (n = 17) and transplant-naive (n = 24) patients with relapsed/refractory NHL. Median treatment cycles were 2 and 1.5, respectively. MTD was 175 mg for both populations; dose-limiting toxicities were grade 4 thrombocytopenia and neutropenia. Most treatment-related adverse events were grade 1/2; drug-related grade 3/4 events included thrombocytopenia and neutropenia. Four patients achieved responses (three complete and one partial at doses ≥ 150 mg, all post-transplant relapsed patients) for an overall response rate of 9.8%. BI 2536 exhibited multi-compartmental pharmacokinetics with a high volume of distribution. The activity and safety of BI 2536 in this pretreated patient population support Plk inhibitors as a therapeutic strategy in oncology.

Background Volasertib (BI 6727) is a potent and selective cell-cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Polo-like kinase (Plk). This phase I dose-escalation study evaluated the maximum tolerated dose (MTD) of volasertib, safety and efficacy, and pharmacokinetic (PK) parameters. Methods This trial followed an open-label, toxicity-guided dose-titration design. Patients with progressive advanced or metastatic solid tumours received a single 1-h infusion of volasertib every 3 weeks. A total of 65 patients were treated at doses of 12–450 mg. Results Reversible haematological toxicity was the main side-effect; thrombocytopenia, neutropenia, and febrile neutropenia constituting the main dose-limiting events. Anaemia (all grades 22%; grade 3: 8%), neutropenia (15%; grade 3/4: 14%), fatigue (15%; grade 3: 2%), and thrombocytopenia (14%; grade 3/4: 14%) were the most frequent drug-related adverse events. The MTD was 400 mg; however, 300 mg was the recommended dose for further development based on overall tolerability. Three patients achieved confirmed partial response. Stable disease as best response was reported in 40% of patients. Two patients remained progression free for >1 year. PK analysis showed no indication of deviation from ‘dose-linear PK’ behaviour, a large volume of distribution (>4000 l), moderate clearance and a long half-life (∼111 h). Conclusion This first-in-man trial demonstrated a favourable PK profile of volasertib, with manageable toxicities. As expected, the most common events were haematological. Encouraging preliminary antitumour activity has been observed, supporting Plk inhibition as a therapeutic approach. Clinical development of volasertib in phase II monotherapy and combination trials is ongoing.

Objective To investigate the efficacy, safety, and pharmacokinetics of two dosing schedules of BI 2536, a novel polo-like kinase-1 inhibitor, in patients with relapsed stage IIIB/IV non-small cell lung cancer. Methods Ninety-five patients were randomized to intravenous BI 2536 on day 1 (200 mg) or days 1 to 3 (50 or 60 mg) of a 21-day treatment course. BI 2536 doses were escalated beyond course 2 if well tolerated. The primary objective was response, and the secondary objectives were progression-free survival (PFS) and overall survival (OS), quality of life, safety, and pharmacokinetics. Primary statistical aim was to demonstrate the difference in objective response rate to historical placebo for both treatment groups. Results Four patients (4.2%) had a partial response; two were confirmed by independent review. Median PFS was 8.3 weeks (58 days 95% confidence interval [CI]: 48–85) and 7 weeks (49 days 95% CI: 46–70) assessed by investigator and independent review, respectively. Median OS was 28.7 weeks (201 days 95% CI: 180–305). No statistically significant difference was observed between the two treatment schedules regarding clinical benefit, PFS, or OS. Grade 4 neutropenia occurred in 37% of patients; common nonhematologic adverse events were fatigue (31%) and nausea (27%). Two deaths (pulmonary hemorrhage and sepsis) were considered drug related. There was a trend in favor of the days 1 to 3 dosing schedule in quality of life. BI 2536 displayed moderate interpatient variability. Conclusions BI 2536 monotherapy has modest efficacy and favorable safety in relapsed non-small cell lung cancer. The findings support the further development of polo-like kinase-1 inhibitors within this indication.

Aims: BI 2536 is a selective and potent small-molecule inhibitor of polo-like kinase 1. We performed a multi-centre, multi-tumour phase II trial to investigate the efficacy, safety and pharmacokinetics of BI 2536 in five solid tumour types. Patients and methods: Patients with advanced head and neck, breast and ovarian cancer, soft tissue sarcoma and melanoma were selected according to protocol-defined general and tumour-specific criteria. They were >= 18 years old, had a good performance status, adequate bone marrow, renal and liver function, measurable progressive disease and had completed other relevant systemic treatments >4 weeks ago. BI 2536 200-250 mg was given intravenously on day 1 every 3 weeks until intolerance, progression or refusal. The study was based on a Simon two-stage design, with 12 patients entering in stage 1 and additional 25 patients to be entered in case of at least one response in the first stage. The rate of objective responses (RECIST criteria) was chosen as primary end-point. Results: Seventy six patients were included, 71 started treatment and received a median number of two cycles (four in ovarian cancer). Frequent grade 3-4 adverse events were neutropaenia (81.6%), thrombocytopaenia (19.7%), febrile neutropaenia (19.7%), anaemia (15.5%) and pain (9.9%). We did not observe confirmed objective responses. All cohorts were closed after the entry of 14-15 eligible non-responding patients. Pharmacokinetic analyses revealed multi-compartmental behaviour and a rapid distribution of BI 2536. Conclusions: BI 2536 showed limited antitumour activity according to the design of this trial in five different tumour types. Derivatives of BI 2536 with a more favourable pharmacological profile are currently explored further in prospective studies. (C) 2010 Elsevier Ltd. All rights reserved.

Polo-like kinases (Plks) play an important role in cell cycle checkpoint controls and are over-expressed in acute myeloid leukaemia (AML). BI 2536, a novel Plk inhibitor, induces mitotic arrest and apoptosis. In this phase I/II trial of BI 2536 in 68 elderly patients with relapsed/refractory AML, three schedules were investigated (day 1, days 1-3, and days 1 + 8). Maximum tolerated dose was 350 and 200 mg in the day 1 and days 1 + 8 schedules, respectively. The day 1-3 schedule appeared equivalent to the day 1 schedule and was discontinued early. BI 2536 exhibited multi-compartmental pharmacokinetic behaviour. The majority of patients showed an increase of bone marrow cells in G2/M with a characteristic pattern of mitotic catastrophe. The overall response rate in the day 1 and day 1 + 8 schedules was 9% (5/54) with 2 complete and 3 partial responses. The majority of drug-related adverse events grade ≥3 were haematological. Taken together, Plk inhibition induced cell cycle arrest in AML blasts in vivo and BI 2536 monotherapy showed modest clinical activity in this poor prognosis patient group.

Introduction BI 2536 is a potent, highly selective inhibitor of polo-like kinase (Plk) 1. This open-label, phase I study investigated the maximum tolerated dose (MTD), safety, efficacy, and pharmacokinetics (PK) of BI 2536 IV in combination with standard-dose pemetrexed in previously treated advanced or metastatic non–small-cell lung cancer. Patients and Methods A standard 3 + 3 design was used. The patients received 500 mg/m 2 pemetrexed and escalating doses of BI 2536 on day 1 every 3 weeks. The primary objective was the MTD of BI 2536 combined with pemetrexed. Secondary endpoints were response rate (Response Evaluation Criteria in Solid Tumors), overall safety, and PK. Results Forty-one patients received BI 2536 (100-325 mg). Two dose-limiting toxicities (DLT) occurred at BI 2536 325 mg (grade 3 pruritus and rash; grade 4 neutropenia). Therefore, the MTD for BI 2536 in combination with pemetrexed was 300 mg. After expanding the MTD dose level, 3 additional patients experienced DLTs, which resulted in expansion of the 250 mg cohort, in which 4 of the 13 additional patients experienced DLTs. Therefore, the recommended dose of BI 2536 was 200 mg. Most frequently reported drug-related adverse events were fatigue (71%), nausea (37%), and rash (34%). Two patients had durable confirmed partial responses; 21 (54%) patients had stable disease after the treatment cycle 2. PK analysis showed that BI 2536 and pemetrexed exposure were not altered when coadministered. Conclusion BI 2536 200 mg combined with standard-dose pemetrexed has an acceptable safety profile in relapsed non–small-cell lung cancer. The antitumor activity observed is encouraging and supports further investigation of Plk inhibitors.

Purpose: This phase I, open-label, dose-escalation study investigated the maximum tolerated dose (MTD) of BI 2536, a small-molecule polo-like kinase (Plk)–1 inhibitor, in two treatment schedules in patients with advanced solid tumors. Secondary objectives included evaluation of safety, efficacy, and pharmacokinetics. Experimental Design: Patients received a single i.v. dose of BI 2536 as a 1-hour infusion on days 1 and 8 or a single 24-hour infusion on day 1 of each 21-day treatment course. MTD determination was based on dose-limiting toxicities. Results: Forty-four and 26 patients received each treatment schedule, respectively. The MTD of BI 2536 in the day 1 and 8 schedule was 100 mg per administration (200 mg per course). The MTD for the second dosing schedule was not determined; a 225-mg dose was well tolerated. The most frequently reported treatment-related nonhematologic adverse events were gastrointestinal events and fatigue. Hematotoxicity as the most relevant side effect was similar in both schedules; neutropenia grades 3 and 4 were observed in 16 patients (36.4%) of the day 1 and 8 schedule and 13 patients (50%) of the 24-hour infusion. Fourteen patients (32%) treated in the day 1 and 8 dosing schedule had a best overall response of stable disease. Plasma concentrations of BI 2536 increased dose proportionally, with no relevant accumulation of exposure in the day 1 and 8 dosing schedule. The average terminal half-life was 50 hours. Conclusions: BI 2536 administered in either treatment schedule has adequate safety in patients with advanced solid tumors, warranting further clinical investigation of polo-like kinase–1 inhibitors. Clin Cancer Res; 16(18); 4666–74. ©2010 AACR.

Abstract 411 Background: LDAC is an established treatment option for patients (pts) with AML considered ineligible for intensive remission induction treatment. However, the outlook for pts who receive LDAC remains unsatisfactory, and novel therapeutic strategies are needed to improve clinical outcome in these pts. Plk1 plays a key role in mitosis and cell cycle progression and is an attractive target for novel therapeutic approaches in cancer. Volasertib (V) is a first-in-class, selective and potent cell cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Plks. The phase I part of this trial determined the maximum tolerated dose of V in combination with LDAC (V + LDAC) to be 350 mg and demonstrated antileukemic activity of V and V + LDAC in pts with relapsed/refractory AML ineligible for intensive therapy (Bug et al, ASH 2010 and 2011). Here we present preliminary phase II data for the randomized comparison of V + LDAC vs LDAC in pts with newly diagnosed AML ineligible for intensive treatment. Methods: In the phase II part of this open-label study, eligible pts were randomized to receive V (350 mg 1-hr intravenously, days 1, 15 Q4W) + LDAC (20 mg bid subcutaneously, days 1–10 Q4W), or LDAC alone until progression/relapse or intolerance. The primary endpoint was objective response (complete remission [CR] or CR with incomplete blood count recovery [CRi]); secondary endpoints included event-free survival (EFS), overall survival (OS), safety and pharmacokinetics (PK). Results: 87 pts were treated with V + LDAC (n=42) or LDAC (n=45). Pt characteristics (V + LDAC/LDAC) were largely balanced: median age, 75/76 yrs; secondary AML, 40.5%/64.4%; adverse cytogenetic group, 35.7%/33.3%. At time of analysis (February 22 2012) 15 pts were still on treatment (12 with V + LDAC). Pts received a median (range) of 2 (1–12) cycles of V + LDAC and 2 (1–11) cycles with LDAC. A significantly greater proportion of pts who received V + LDAC achieved a CR or CRi compared with pts who received LDAC (31.0% vs 11.1%; odds ratio 3.59 [95% CI: 1.15, 11.18]; P = 0.0277), with a median (range) time to remission of 71 (29–158) days and 69 (34–125) days, respectively. Remissions with V + LDAC were observed across genetic groups, including pts with adverse cytogenetics. A trend for longer median EFS was observed for pts who received V + LDAC compared with those who received LDAC (HR 0.61 [95% CI: 0.35, 1.05]; P = 0.0725; Figure). Follow-up for OS was ongoing at the time of this analysis. Among pts achieving CR/CRi, only 2 had experienced recurrence or death at the time of analysis (1 in each arm after a remission duration of 57 [V + LDAC] or 67 [LDAC] days). For all other pts ongoing in remission, the remission duration was censored after 53–407 days (LDAC + V) or 32–282 days (LDAC), consistent with prolonged duration of remission in some pts. The most frequent all grade adverse events (AEs) in the V + LDAC arm were febrile neutropenia (50%), constipation (45.2%), nausea (40.5%) and anemia (40.5%). In the LDAC arm, the most common all grade AEs were nausea (33.3%), anemia (28.9%), pyrexia (28.9%), and constipation, asthenia and diarrhea (26.7% each). More pts who received V + LDAC experienced ≥ grade 3 AEs than those who received LDAC (95.2% vs 68.9%), particularly for blood and lymphatic system disorders (81.0% vs 44.4%), gastrointestinal disorders (21.4% vs 6.7%), and infections and infestations (45.2% vs 22.2%). The early death rates (V + LDAC/LDAC) at 30, 60 and 90 days were comparable between the two treatment arms: 30 days, 9.5%/8.9%; 60 days, 21.5%/17.8%; 90 days, 28.9%/33.4% (rates calculated using Kaplan-Meier method). PK analyses demonstrated that V is a moderate clearance drug with multi-compartmental PK behavior, a large volume of distribution and a long terminal half-life. Preliminary data suggest no drug-drug interactions following combination of V with LDAC. Conclusions: These preliminary phase II data demonstrate a significantly improved CR/CRi rate and a trend for EFS benefit with V + LDAC compared with LDAC alone in pts with newly diagnosed AML ineligible for intensive treatment. An increased frequency of AEs was observed with the addition of V, which was expected given its myelosuppressive mechanism of action; available data do not suggest increased early mortality for V + LDAC vs LDAC. A confirmatory phase III trial is needed to determine the clinical benefit of V + LDAC in pts with AML ineligible for intensive treatment. Disclosures: Off Label Use: Volasertib is an investigational agent. Fiedler:Pfizer, Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Bug:Boehringer Ingelheim: Honoraria, Membership on an entity's Board of Directors or advisory committees. Müller-Tidow:Boehringer Ingelheim: Research Funding. Voss:Boehringer Ingelheim: Employment. Taube:Boehringer Ingelheim: Employment. Fritsch:Boehringer-Ingelheim: Employment. Döhner:Celgene, Amgen, Ambit, Astellas, Lilly: Consultancy.

Abstract 1549 Background: The prognosis of patients (pts) with relapsed or refractory (rel/ref) AML who are considered unlikely to benefit from or tolerate intensive salvage treatment is unfavorable and novel treatment strategies are needed. Repeated cycles of LD-Ara-C are a therapeutic option for palliative treatment; however, the outlook for these pts remains unsatisfactory. Plks are critical in cellular division and mitotic progression and Plk1 is overexpressed in many cancers including AML. Volasertib is a first in class, selective and potent cell cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Plk. In phase I/II trials in pts with solid tumors, volasertib demonstrated a favorable safety profile and encouraging antitumor activity. Here, we present updated results from the phase I part of an ongoing phase I/II study of volasertib in combination with LD-Ara-C or as monotherapy in AML pts considered ineligible for intensive salvage treatment. Material and Methods: This study follows a two-stage design. The phase I part, reported here, investigates the maximum tolerated dose (MTD) of volasertib as a 1-hr intravenous infusion on days 1 and 15 Q4W as monotherapy or in combination with fixed dose LD-Ara-C 20 mg bid subcutaneously on days 1–10 Q4W in pts with rel/ref AML. Dose escalation follows a 3+3 design with de-escalation. Blood samples for pharmacokinetic (PK) analyses were taken in cycles 1 and 2 and concentrations of volasertib and LD-Ara-C were determined. Results: In the monotherapy arm, increasing volasertib doses (150, 200, 350, 400, 450 mg) were evaluated in 29 pts (median age: 71 yrs [range 26–84]). Drug-related adverse events (AEs) were reported in 8 pts (27.6 %). Most frequent drug-related AEs (>5%) were anemia in 3 pts (10.3%), and thrombocytopenia, epistaxis, and nausea in 2 pts each (6.9%). Grade 3/4 drug-related AEs included thrombocytopenia (2 cases), anemia, diarrhea, mucositis, neutropenia, and pneumonia (1 case each); there was 1 fatal (grade 5) drug-related AE (fungal pneumonia). Of the drug-related AEs, the following were dose-limiting toxicities (DLTs) per protocol: grade 4 pneumonia and fatal fungal pneumonia (n=1, at 150 mg), and grade 3 mucositis (n=1, at 400 mg). Monotherapy dose escalation is ongoing; pts have received volasertib doses of 500 mg without having reached the MTD. Preliminary best response data indicated minor antileukemic activity at low doses (150 and 200 mg); with 4/13 pts achieving no change as best response, mostly of short duration (median number of cycles initiated: 1 [range 1–5]). At higher monotherapy doses (≥350 mg), antileukemic activity was observed with 4/16 pts achieving a complete remission with incomplete blood count recovery (CRi) and 5/16 having temporarily stable blood values as best response. In the combination arm, volasertib doses of 150–400 mg were investigated. The MTD for volasertib in combination with LD-Ara-C was 350 mg (Bug et al ASH 2010). Seven out of 32 pts treated with volasertib + LD-Ara-C achieved a complete remission (CR or CRi). In responding patients, a median number of 6 treatment cycles was initiated (range 3–13) and a preliminary analysis revealed a median overall survival of 551 days (range 165–595). PK analysis showed that volasertib is a moderate clearance drug with multi-compartmental PK behavior with a large volume of distribution (>4000 L) and a long terminal half-life (∼111 hrs). No drug interaction after co-administration of LD-Ara-C was observed. Conclusions: The phase I part of the study determined the MTD of volasertib in combination with LD-Ara-C to be 350 mg; the MTD of volasertib monotherapy has not yet been determined. Volasertib was well tolerated in this heavily pretreated AML pt population at doses above the recommended phase II volasertib dose used in pts with solid tumors. Most of the reported higher grade drug-related AEs were due to the myelosuppressive effect of volasertib. Preliminary results from the phase I trial show antileukemic activity of volasertib as monotherapy and in combination with LD-Ara-C. These results indicate Plk to be a potential new target for AML treatment and warrant proceeding with further clinical investigation of volasertib in AML pts. Disclosures: Bug: Novartis Pharma GmbH: Consultancy, Honoraria; Celgene GmbH: Consultancy, Honoraria. Off Label Use: Volasertib is an investigational agent. Müller-Tidow:Boehringer Ingelheim: Research Funding. Krug:Boehringer Ingelheim: Research Funding. Voss:Boehringer Ingelheim: Employment. Taube:Boehringer Ingelheim: Employment. Fritsch:Boehringer Ingelheim: Employment. Garin-Chesa:Boehringer Ingelheim: Employment. Ottmann:Boehringer Ingelheim: Consultancy. Döhner:Celgene, Clavis: Membership on an entity's Board of Directors or advisory committees.