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As vosaroxin as a fluoroquinolone (FQ) had anticancer effectiveness; this study aimed to screen new lipophilic FQs for their dual antimicrobial-antiproliferative activities. Using sulforhodamine B assay; 36 lipophilic FQs have been screened for antimicrobial propensities against S. aureus, E. coli, and C. albicans vs. the respective references ciprofloxacin and fluconazole. They were also explored against a battery of cancer cell lines. Normal periodontal ligament fibroblasts (PDL) were tested for safety examination in comparison to the cisplatin. Reduced FQ compound 4g (R-2, 4-DMeOACA) highly scored nanomolar potency with MIC value of 0.004 µM against gram-positive bacteria. The highest activity of the 36 lipophilic FQs was noted on Leukaemia K562, cervical HELA and pancreatic PANC-1 cancer cell lines with respective IC50 value of 0.005 µM for compound R-4-BuACA (4e), 0.40 µM with CHxCA (7a) and 0.11 µM for R-4-HxACA (4f). Tested FQs exhibited cytotoxicity in A549 lung cancer, MCF-7 and T47D breast cancer cell lines. The reduced 4e and 4f compounds have shown nanomolar inhibition against K562 (as of 4e), PANC-1 and MCF-7 (as of 4f) with IC50 values of 0.005, 0.11 and 0.30 µM, respectively. Succinctly FQs' dual gram-positive antibacterial-antineoplastic capacities expand on of drug design scaffolds in lead generation.br /.

Refractory/early relapsed (Ref/eRel) acute myeloid leukemia (AML) in patients ≥60 years old is the most important unmet medical need in the salvage setting, where outcomes are exceptionally poor and no standard of care exists.[1][1] Vosaroxin is a first-in-class anticancer quinolone derivative

Acute myeloid leukemia (AML) represents a disease with a very poor outcome and remains an area of significant unmet need necessitating novel therapeutic strategies. Among novel therapeutic agents, vosaroxin is a first-in-class anticancer quinolone derivative that targets topoisomerase II and induces site-selective double-strand breaks in DNA, leading to tumor cell apoptosis. Areas covered: Herein, the authors provide a comprehensive review of the preclinical development of vosaroxin. This includes coverage of vosaroxin's mechanism of action in addition to its pharmacology and of the main studies reported over the past few years with vosaroxin when used to treat adult AML. Expert opinion: Given that vosaroxin is associated with fewer potential side effects, it may be of benefit to elderly patients with relapsed/refractory AML and to those with additional comorbidities who have previously received an anthracycline and cytarabine combination. Furthermore, vosaroxin also was seen to be active in multidrug-resistant preclinical models. However, further studies have to be performed to better evaluate its place in the armamentarium against AML.

In spite of CR rates of 75-80% currently achieved with anthracycline-cytarabine regimens in younger patients with favorable and intermediate-risk AML, relapse remains a major issue. The French AML intergroup launched the BIG-1 trial in 2015 in order to test different strategies aiming at reducing relapse rate and improving survival. All patients with previously untreated non-APL and non-CBF AML aged 18-60 years are eligible for trial participation which is still ongoing. The trial design includes several randomizations (R): Idarubicin vs daunorubicin for induction (R1), HDAC vs IDAC for consolidation (R2), post-transplant GVHD prophylaxis modalities (R3). R4 consists of nested randomized phase 2-3 trials testing the addition of new drugs to the IDAC or HDAC backbones during the consolidation phase. The protocol was designed to allow the sequential evaluation of several new agents over the trial period. Vosaroxin (VOS) has shown antileukemic activity (Advani, Clin Cancer Res 2010). The combination of VOS and IDAC showed higher CR rate and a non-significant OS benefit as compared to a placebo-IDAC arm in a large phase 3 trial in patients with refractory/relapsed AML (Ravandi Lancet Oncol 2015). We hypothesized that the addition of VOS to IDAC would improve LFS as compared to IDAC alone when given during the consolidation phase. Methods. Eligibility criteria in the BIG-1 trial include: previously untreated AML according to WHO 2016 classification (AML secondary to an untreated myelodysplastic syndrome allowed), age 18-60, ECOG PS 0-2, no cardiac contra-indication to anthracyclines. Patients with APL and patients with CBF-AML are excluded. Eligibility criteria for R4 randomization were: Patients in first CR/CRp/CRi following 1 or 2 courses of induction chemotherapy according to the BIG-1 protocol; ELN2010 favorable- and intermediate-risk groups; ECOG PS ≤ 3; Absence of severe uncontrolled infection. Patients were scheduled to receive Cytarabine: 1.5 gr/m² twice daily on D1, 3, 5 with or without Vosaroxin: 70 mg/m² on D1 and D4 per cycle for a maximum of three cycles at 4-6 weeks intervals. Patients scheduled for allo-SCT or those who had reached CR after 2 induction cycles were to receive only 2 cycles of VOS-IDAC/IDAC. R4-VOS sub-trial was designed to detect an increase of the 18-month LFS from 55% to 75% using a two-step phase 2-3 study. With type I and II errors set at 20% and using a one-sided test, 70 patients had to be randomized. If the predefined statistical objectives were met, study would resume recruiting 130 additional patients in the phase 3 part for a total of 200 patients. Results. 70 patients (35 in each arm), median age 47, ELN 2010 favorable and intermediate risk groups, have been included. 94% had de novo AML with NPM1 mutations in 46% and FLT3-ITD in 20%. As shown in the Table, patients and disease characteristics were not different between the 2 arms except for slightly more patients in CRi in the VOS-IDAC arm. Patients received a median of 4 chemotherapy cycle (including induction; range 3-4) without difference between the treatment arms. 13 patients (18.5%) received an alloSCT (VOS-IDAC: 5, IDAC: 8). Time between cycle 1 and cycle 2 was significantly longer in the VOS-IDAC arm (p= 0.017). Hematologic toxicity was higher in the VOS-IDAC group with a significantly longer neutropenia duration after each cycle, a greater number of RBC and Platelet transfusions, a significantly greater number of days with antibiotics and antifungal therapies and days with fever (during cycle 1). There were also significantly more cutaneous toxicity, mild nausea/vomiting and diarrhea in the VOS-IDAC arm. With a median follow-up of 19 months, 14 and 15 patients relapse in the VOS-IDAC vs IDAC arms respectively. The study primary endpoint has not been reached and LFS was not significantly higher in the VOS-IDAC arm (18-month LFS of 51% vs 46% for VOS-IDAC vs IDAC respectively; see Figure) even after accounting for allo-SCT as a time-dependent variable (p-value=.49). The 2-year CIR was 51% vs 46% (p=NS) and 2-year OS was 88% vs 68% (p=NS). Conclusion, the study's primary endpoint has not been met and results fail to show a significant improvement of 18-month LFS with the addition of VOS to IDAC consolidation of favorable/intermediate-risk AML in first CR. The phase 3 part of the trial will not open. The BIG-1 trial is still ongoing and uses the same design to tests addition of other drugs to the IDAC/HDAC consolidation backbone. Disclosures Guieze: abbvie: Honoraria, Other: advisory board, travel funds; janssen cilag: Honoraria, Other: advisory board, travel funds; roche: Other: travle funds; gilead: Honoraria, Other: travel funds; astrazanecka: Honoraria, Other: advisory board. Dombret:Pfizer: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Nova: Consultancy, Research Funding; Celgene: Consultancy; Jazz Pharma: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Sunesis: Consultancy; Servier: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Astellas: Consultancy; Menarini: Consultancy; Janssen: Consultancy; Cellectis: Consultancy; Shire-Baxalta: Consultancy; Immunogen: Consultancy; Otsuka: Consultancy; Abbvie: Consultancy. Hunault:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Diachi: Membership on an entity's Board of Directors or advisory committees; Jansen: Honoraria; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees.

Introduction: Topoisomerase II inhibitors have long been used in the frontline and as salvage therapy for AML, with daunorubicin and idarubicin being prototypical agents in this therapeutic class, classically in combination with nucleoside analogs, e.g. cytarabine. Most recently, several other compounds from this drug class have or are being investigated. Areas covered: The current paper reviews older and newer topoisomerase II inhibitors in clinical development for the treatment of AML. The authors discuss the clinical use of these agents, current trials involving them as well as their safety profile. Important side effects of these medications including therapy-related AML (t-AML) are also covered. Expert opinion: Topoisomerase II inhibitors have helped improve outcomes in AML. Recently, the FDA approved several agents including CPX-351 for the treatment of secondary and t-AML. CPX-351 may have applicability in other high-risk myeloid diseases. Future directions include a combination of these agents with other targeted therapies. Finally, the authors believe that small molecule inhibitors, such as venetoclax and possibly immunotherapy options could also be incorporated to our treatment paradigm in selected patients.

Vosaroxin is a quinolone compound that intercalates DNA and induces TP53-independent apoptosis, demonstrating activity against acute myeloid leukemia (AML) in Phase I–III trials. Here, we examine vosaroxin’s mechanism of action and pharmacology, and we review its use in AML to date, focusing on details of individual clinical trials. Most recently, when combined with cytarabine in a randomized Phase III trial (VALOR), vosaroxin improved outcomes versus cytarabine alone for relapsed/refractory AML in patients older than 60 years and for patients in early relapse. We consider its continued role in the context of a multifaceted strategy against AML, including its current use in clinical trials. Prospective use will define its role in the evolving landscape of AML therapy.

Introduction: A first-in-class anticancer quinolone derivative with topoisomerase II activity, mechanistically, vosaroxin is similar to the anthracycline class. However, vosaroxin displays advantageous pharmacokinetic properties such as minimal metabolism, a lack of free radical production, is not a substrate for the P glycoprotein efflux pump, and can exert its antineoplastic activity independently of P53 function. Vosaroxin has shown encouraging results when combined with cytarabine in older patients with relapsed or refractory acute myeloid leukemia (AML) while balancing early toxicity and mortality, making it a compelling novel therapy for acute myelogenous leukemia.Areas covered: Herein, we review the clinical data from published and internationally presented clinical trials utilizing vosaroxin for AML in the elderly, and relapsed and refractory population. Pivotal trials reviewed include the multicenter, phase II, REVEAL-1 study of single-agent vosaroxin in untreated elderly patients and the...

The outcomes of patients with relapsed or refractory acute myeloid leukemia (AML) are dismal, and effective treatment options in this patient population are therefore desperately needed. Vosaroxin is a first-in-class anticancer quinolone derivative that has shown promising activity in patients with relapsed or refractory AML.Studies in relapsed/refractory AML, including a large randomized phase III trial, have shown improved response rates when vosaroxin was combined with cytarabine, which translated to prolonged survival in certain subsets of patients, including older patients. Given the encouraging results of vosaroxin in the relapsed/refractory setting, several studies are also evaluating vosaroxin in older patients with untreated AML who are not candidates for intensive chemotherapy. The results from clinical trials evaluating vosaroxin in both treatment naïve and relapsed/refractory AML will be reviewed. Expert Commentary: Vosaroxin has shown significant promise in the management of AML, especially in older patients with relapsed/refractory disease. As vosaroxin has been associated with increased toxicity in some studies, appropriate dosing and patient selection will be crucial to determine the future role of vosaroxin in AML.

In the late 1980s, reports emerged describing experimental antibacterial quinolones having significant potency against eukaryotic Type II topoisomerases (topo II) and showing cytotoxic activity against tumor cell lines. As a result, several pharmaceutical companies initiated quinolone anticancer programs to explore the potential of this class in comparison to conventional human topo II inhibiting antitumor drugs such as doxorubicin and etoposide. In this review, we present a modern re-evaluation of the anticancer potential of the quinolone class in the context of today’s predominantly pathway-based (rather than cytotoxicity-based) oncology drug R&D environment. The quinolone eukaryotic SAR is comprehensively discussed, contrasted with the corresponding prokaryotic data, and merged with recent structural biology information which is now beginning to help explain the basis for that SAR. Quinolone topo II inhibitors appear to be much less susceptible to efflux-mediated resistance, a current limitation of therapy with conventional agents. Recent advances in the biological understanding of human topo II isoforms suggest that significant progress might now be made in overcoming two other treatment-limiting disadvantages of conventional topo II inhibitors, namely cardiotoxicity and drug-induced secondary leukemias. We propose that quinolone class topo II inhibitors could have a useful future therapeutic role due to the continued need for effective topo II drugs in many cancer treatment settings, and due to the recent biological and structural advances which can now provide, for the first time, specific guidance for the design of a new class of inhibitors potentially superior to existing agents.

BACKGROUND: Safe and effective treatments are urgently needed for patients with relapsed or refractory acute myeloid leukaemia. We investigated the efficacy and safety of vosaroxin, a first-in-class anticancer quinolone derivative, plus cytarabine in patients with relapsed or refractory acute myeloid leukaemia. METHODS: This phase 3, double-blind, placebo-controlled trial was undertaken at 101 international sites. Eligible patients with acute myeloid leukaemia were aged 18 years of age or older and had refractory disease or were in first relapse after one or two cycles of previous induction chemotherapy, including at least one cycle of anthracycline (or anthracenedione) plus cytarabine. Patients were randomly assigned 1:1 to vosaroxin (90 mg/m(2) intravenously on days 1 and 4 in a first cycle; 70 mg/m(2) in subsequent cycles) plus cytarabine (1 g/m(2) intravenously on days 1-5) or placebo plus cytarabine through a central interactive voice system with a permuted block procedure stratified by disease status, age, and geographical location. All participants were masked to treatment assignment. The primary efficacy endpoint was overall survival and the primary safety endpoint was 30-day and 60-day all-cause mortality. Efficacy analyses were done by intention to treat; safety analyses included all treated patients. This study is registered with ClinicalTrials.gov, number NCT01191801. FINDINGS: Between Dec 17, 2010, and Sept 25, 2013, 711 patients were randomly assigned to vosaroxin plus cytarabine (n=356) or placebo plus cytarabine (n=355). At the final analysis, median overall survival was 7·5 months (95% CI 6·4-8·5) in the vosaroxin plus cytarabine group and 6·1 months (5·2-7·1) in the placebo plus cytarabine group (hazard ratio 0·87, 95% CI 0·73-1·02; unstratified log-rank p=0·061; stratified p=0·024). A higher proportion of patients achieved complete remission in the vosaroxin plus cytarabine group than in the placebo plus cytarabine group (107 [30%] of 356 patients vs 58 [16%] of 355 patients, p

Vosaroxin is a quinolone-derivative anticancer agent with inhibitory activity on type II DNA topoisomerases (TOP2). The aim of the present study was to investigate its cytotoxic effect and potential molecular mechanisms in human cervical cancer HeLa cells. Vosaroxin decreased cell viability and increased lactate dehydrogenase (LDH) release in a dose- and time-dependent manner in HeLa cells, but not in normal cervical epithelial cells. Vosaroxin also induced apoptosis and increased caspase-3 activity in HeLa cells. These effects were accompanied by increased mitochondrial reactive oxygen species (ROS) generation, lipid peroxidation, mitochondrial swelling and reduced ATP production. Western blot analysis showed that vosaroxin significantly reduced hypoxia-inducible factor 1α (HIF-1α) protein levels. However, it had no effect on HIF-1α protein degradation and HIF-1α mRNA levels. The results showed that vosaroxin inhibited the synthesis of HIF-1α protein and interfered with the dimerization of HIF-1α and aryl hydrocarbon receptor nuclear translocator (ARNT). In addition, vosaroxin stimulated mitochondrial enzyme activities and superoxide dismutase 2 (SOD2) deacetylation via activating (Sir2 like protein 3) Sirt3. More importantly, vosaroxin-induced inhibition on HIF-1α and its cytotoxic effects, as measured by cell viability, LDH release and apoptosis, were partially prevented by Sirt3 knockdown or the AMP-activated protein kinase (AMPK) inhibitor compound C. Overall, vosaroxin is demonstrated to be a chemotherapeutic agent targeting the Sirt3/HIF-1 pathway and could be beneficial for inducing cytotoxicity in human cervical cancer cells.

The Fe(iii)-binding constant of vosaroxin, an anticancer quinolone derivative, has been determined spectrophotometrically and compared with the analogous Fe(iii) complex formed with doxorubicin. The in vivo metabolic stability and iron coordination properties of the quinolones compared to the anthracylines may provide significant benefit to cardiovascular safety. The mechanism of action of both molecules target the topoisomerase II enzyme. Both doxorubicin (Hdox, log βFeL3 = 33.41, pM = 17.0) and vosaroxin (Hvox, log βFeL3 = 33.80(3), pM = 15.9) bind iron(iii) with comparable strength; at physiological pH however, [Fe(vox)3] is the predominant species in contrast to a mixture of species observed for the Fe:dox system. Iron(iii) nitrate and gallium(iii) nitrate at a 1 : 3 ratio with vosaroxin formed stable tris(vosaroxacino)-iron(iii) and tris(vosaroxino)gallium(iii) complexes that were isolated and characterized. Their redox behavior was studied by CV, and their stereochemistry was further explored in temperature dependent (1)H NMR studies. The molecular pharmacology of their interaction with iron(iii) may be one possible differentiation in the safety profile of quinolones compared to anthracyclines in relation to cardiotoxicity.

Background Vosaroxin is a first-in-class anticancer quinolone derivative that is being investigated for patients with relapsed or refractory acute myeloid leukemia (AML). The primary objective of this study was to quantitatively determine the pharmacokinetics of vosaroxin and its metabolites in patients with advanced solid tumors. Methods This mass balance study investigated the pharmacokinetics (distribution, metabolism, and excretion) of vosaroxin in cancer patients after a single dose of 60 mg/m2 14C-vosaroxin, administered as short intravenous injection. Blood, urine and feces were collected over 168 h after injection or until recovered radioactivity over 24 h was less than 1% of the administered dose (whichever was earlier). Total radioactivity (TRA), vosaroxin and metabolites were studied in all matrices. Results Unchanged vosaroxin was the major species identified in plasma, urine, and feces. N-desmethylvosaroxin was the only circulating metabolite detected in plasma, accounting for

Treatment for acute myeloid leukemia (AML) generally consists of a combination of cytarabine and an anthracycline. Although induction therapy leads to complete remission (CR) for most patients, refractoriness to chemotherapy or relapse after initial response is associated with poor outcomes. The 1-year survival rates after first relapse have been reported at 29%, declining to 11% at 5 years. Prognosis is particularly poor among older patients whose higher prevalence of unfavorable cytogenetics and high frequency of comorbidities diminish their ability to tolerate intensive chemotherapy. There is no standard of care for relapsed/refractory (R/R) AML, and no new therapies have shown consistently superior outcomes in this setting in over two decades. Vosaroxin is an anticancer quinolone derivative (AQD) that was evaluated in combination with cytarabine for the treatment of R/R AML in the randomized, double-blind, placebo-controlled, phase III VALOR study ( n = 711). Compared with placebo/cytarabine, the vosaroxin/cytarabine regimen demonstrated favorable CR rates and survival in patients ⩾60 years of age, with toxicities similar to other AML regimens. Here we review outcomes of recent studies of commonly used chemotherapy regimens for the treatment of R/R AML and evaluate the results of the VALOR trial in the context of the current treatment landscape.

Vosaroxin is an anti-cancer quinolone-derived DNA topoisomerase II inhibitor. We investigated vosaroxin with decitabine in patients ≥60 years of age with newly diagnosed acute myeloid leukemia (n=58) or myelodysplastic syndrome (≥10% blasts) (n=7) in a phase II non-randomized trial. The initial 22 patients received vosaroxin 90 mg/m2 on days 1 and 4 with decitabine 20 mg/m2 on days 1-5 every 4-6 weeks for up to seven cycles. Due to a high incidence of mucositis the subsequent 43 patients were given vosaroxin 70 mg/m2 on days 1 and 4. These 65 patients, with a median age of 69 years (range, 60-78), some of whom with secondary leukemia (22%), adverse karyotype (35%), or TP53 mutation (20%), are evaluable. The overall response rate was 74% including complete remission in 31 (48%), complete remission with incomplete platelet recovery in 11 (17%), and complete remission with incomplete count recovery in six (9%). The median number of cycles to response was one (range, 1-4). Grade 3/4 mucositis was noted in 17% of all patients. The 70 mg/m2 induction dose of vosaroxin was associated with similar rates of overall response (74% versus 73%) and complete remission (51% versus 41%, P=0.44), reduced incidence of mucositis (30% versus 59%, P=0.02), reduced 8-week mortality (9% versus 23%; P=0.14), and improved median overall survival (14.6 months versus 5.5 months, P=0.007). Minimal residual disease-negative status by multiparametric flow-cytometry at response (± 3 months) was achieved in 21 of 39 (54%) evaluable responders and was associated with better median overall survival (34.0 months versus 8.3 months, P=0.023). In conclusion, the combination of vosaroxin with decitabine is effective and well tolerated at a dose of 70 mg/m2 and warrants randomized prospective evaluation. ClinicalTrials.gov: NCT01893320.

Vosaroxin is a first-in-class anticancer quinolone derivative that intercalates DNA and inhibits topoisomerase II. This study assessed the safety and tolerability of vosaroxin plus cytarabine in patients with relapsed/refractory acute myeloid leukemia. Escalating vosaroxin doses (10-minute infusion; 10-90 mg/m(2); days 1, 4) were given in combination with cytarabine on one of two schedules: schedule A (24-hour continuous intravenous infusion, 400 mg/m(2)/day, days 1-5) or schedule B (2-hour intravenous infusion, 1 g/m(2)/day, days 1-5). Following dose escalation, enrollment was expanded at the maximum tolerated dose. Of 110 patients enrolled, 108 received treatment. The maximum tolerated dose of vosaroxin was 80 mg/m(2) for schedule A (dose-limiting toxicities: grade 3 bowel obstruction and stomatitis) and was not reached for schedule B (recommended phase 2 dose: 90 mg/m(2)). In the efficacy population (all patients in first relapse or with primary refractory disease treated with vosaroxin 80-90 mg/m(2); n=69), the complete remission rate was 25% and the complete remission/complete remission with incomplete blood count recovery rate was 28%. The 30-day all-cause mortality rate was 2.5% among all patients treated at a dose of 80-90 mg/m(2). Based upon these results, a phase 3 trial of vosaroxin plus cytarabine was initiated in patients with relapsed/refractory acute myeloid leukemia. (Clinicaltrials.gov identifier: NCT00541866).

Background: AML is an aggressive malignancy with a median age of 67 yrs at diagnosis and an age-adjusted 5-yr survival of less than 25%. Most older patients (pts) with AML have poor risk cytogenetic/genetic features associated with suboptimal complete remission (CR) rates and overall survival (OS). Until recently, the anthracycline and cytarabine based induction remained unchanged for over 4 decades. Vosaroxin (Vos) is a first-in-class anticancer quinolone derivative which is thought to induce less cardiac toxicity than standard anthracycline therapy. Vos was previously administered in combination with intermediate dose cytarabine (IDAC) in relapsed/refractory (r/r) AML pts in a large randomized phase 3 trial (VALOR) and demonstrated significantly improved CR rates compared to IDAC alone but without improvement in OS. In the VITAL study, we investigated the combination of infusional cytarabine (iAC) with Vos ("7 + V") in newly diagnosed AML. Methods: VITAL (NCT02658487) is a single-arm, open-label, two-stage phase II study of 90 mg/m2, Vos on days 1 and 4 (reduced to 70 mg/m2, days 1 and 4 in the event of re-induction) and 100 mg/m2 continuous iAC on days 1-7. Oral cryotherapy was administered during Vos administration as prophylaxis for oral mucositis seen in prior studies. Enrollment in stage 1 was limited to 17 evaluable pts >55 yrs of any risk classification or pts 18-54 years with high-risk disease. The two-stage design required CR in more than 7 of the first 17 pts in order to proceed to stage 2. The operating characteristics of the study design provided a 64% probability of early termination if CR occurred in 7 or fewer pts suggesting that the true CR rate would be ≤ 40%. Stage 2 included an additional 24 pts (age 18-54 yrs with intermediate or high-risk disease, or 55 years or older with any risk disease). Response was assessed using the modified IWG-2003 criteria. Results: In total, 42 pts were enrolled and assessed for toxicity. One patient who achieved an aplastic marrow biopsy at day 14, succumbed to an AML-related sepsis event prior to formal response assessment was initially deemed unevaluable for response and replaced but was ultimately included in the response assessment. Baseline demographics of the 42 enrolled pts are seen in Table 1a. Median age was 63 yrs (range, 43-74) and 86% (36/42) were ≥ 55yrs at time of enrollment. Almost all, 40/42 (95%), had intermediate (11/40) or poor (29/40) risk AML. Adverse events (AEs) of special interest of any Grade (Gr) and Gr 3-5 AEs occurring in > 10% of pts are listed in Table 1b. Oral mucositis was observed in 16/42 (38%) pts with 12/42 (29%) having Gr 1-2 and only 4/42 (10%) having Gr 3 severity. Three Gr 5 events occurred (2-Infection/Sepsis; 1-neutropenic colitis). No acute cardiac toxicity was seen. CR was achieved in 20/42 (48%) pts, while 3 additional pts achieved CR with incomplete count recovery (CRi) for a CR/CRi rate of 55% (23/42). CR was observed in 100% (2/2) with favorable risk (both >65 yrs old). CR/CRi was seen in 73% (8/11) intermediate and 45% (13/29) poor risk pts. One poor risk pt with CRi converted to CR in the absence of additional therapy but did so outside of the protocol defined time period for response assessment (Day 57 +/- 3 days) and was recorded as CRi for this analysis. CR/CRi was noted in 40% (4/10) pts whose AML had TP53 mutations. Allogeneic hematopoietic stem cell transplant was performed in 45% (19/42) of pts. Progression-free survival was 43% and OS was 48% for all pts at 1-year of follow-up (Figure 1). Conclusion: The combination of Vos and iAC in newly diagnosed AML pts appears safe. Mucocutaneous complications were observed as noted in previous studies with Vos. Administration of oral cryotherapy during Vos administration appeared to reduce occurrence of oral mucositis during induction, but > Gr 3 neutropenic enterocolitis occurred in 7/42 (17%) pts. Still, the combination appears to be tolerable with an adverse event profile analogous to conventional induction regimens. While the VALOR trial observed Gr 3-5 cardiac AEs in < 1% of the 705 r/r AML pts with prior anthracycline exposure, no attributable cardiac events were seen within the VITAL trial population. Vosaroxin and infusional cytarabine is a clinically active induction regimen which warrants further investigation based on response rates and toxicity profile at least similar to current anthracycline based induction strategies with an apparent absence of cardiac toxicity. Disclosures Strickland: Astellas: Consultancy; Jazz: Consultancy; Kite: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Sunesis: Research Funding; AbbVie: Consultancy. Podoltsev:Alexion: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Research Funding; Kartos Therapeutics: Research Funding; Astellas Pharma: Research Funding; Daiichi Sankyo: Research Funding; Sunesis Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Research Funding; Pfizer: Research Funding; Astex Pharmaceuticals: Research Funding; CTI Biopharma: Research Funding; Celgene: Other: Grant funding, Research Funding; Genentech: Research Funding; AI Therapeutics: Research Funding; Samus Therapeutics: Research Funding; Arog Pharmaceuticals: Research Funding. Zeidan:Acceleron Pharma: Consultancy, Honoraria, Research Funding; Celgene Corporation: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Medimmune/AstraZeneca: Research Funding; Boehringer-Ingelheim: Consultancy, Honoraria, Research Funding; Trovagene: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; ADC Therapeutics: Research Funding; Jazz: Honoraria; Ariad: Honoraria; Agios: Honoraria; Novartis: Honoraria; Astellas: Honoraria; Daiichi Sankyo: Honoraria; Cardinal Health: Honoraria; Seattle Genetics: Honoraria; BeyondSpring: Honoraria. Byrne:Karyopharm: Research Funding. Gore:Celgene Corporation: Consultancy, Research Funding. Savona:Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Patents & Royalties; AbbVie: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Selvita: Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Despite significant advances in diagnosis and supportive care, the majority of patients diagnosed with acute myeloid leukemia (AML) ultimately die of their disease. Standard intensive induction treatment continues to comprise cytarabine and a topoisomerase II (topo II) poison, usually an anthracycline. Vosaroxin , a novel first-in-class quinolone derivative has been developed for use in the treatment of AML as a new-generation topo II inhibitor. It has shown promising activity as a monotherapy and also in combination with intermediate dose cytarabine (IDAC) in relapsed and refractory patient cohorts with minimal toxicity and good tolerability.The authors discuss the mechanism of action of vosaroxin, the pharmacokinetics, safety and tolerability, preclinical and clinical trial results available as well as areas of ongoing research.Vosaroxin has shown efficacy as a novel cytotoxic agent, and despite a similar mechanism of action has significant advantages over anthracyclines. It evades common resistance pathways of p53 and P-glycoprotein (P- gp) and does not appear to generate significant reactive oxygen species (ROS) associated with these agents. Should future investigation confirm its efficacy and advantageous safety profile, vosaroxin could potentially replace older generation topoisomerase poisons in the treatment of AML and other malignant conditions.

A series of novel 2,7-dimethyl-1,8-naphthyridine derivatives substituted with Mannich bases 2a–d, N-β-glycosides 6a–e, 7a–e, Schiff’s bases 8a–c, pyrazolone 9, and S-alkylated derivatives 10a–c have been synthesized in good yields starting from 4-hydroxy-2,7-dimethyl-1,8-naphthyridine 1 through multi-step synthesis. The newly synthesized title compounds were evaluated for their HepG2 cell growth inhibition, the results revealed that all the tested compounds process inhibitory effects on the growth of HepG2 liver cancer cells. Compound 8b showed the highest inhibition activity against HepG2 cell line (IC50 equals 3.2 μg/mL) among all tested compounds. The results were compared to 5-Fluorouracil (5-FU) and doxorubicin as reference drugs, (IC50 5 and 3.56 μg/mL). Furthermore, molecular docking of compounds 3b, 6a, and 8b into the binding site of topoisomerase II was carried out. The results of the binding energy scores of these compounds were compared to the docking score of Vosaroxin, a known 1,8-naphthyridine derivative which is in clinical trials as potential anticancer drug. Compound 8b docking result revealed that it is the only tested compound that intercalate with DNA segment of the topoisomerase II, similar to Vosaroxin which was used as reference drug for docking comparison.

Therapies for AML have remained mostly unchanged since the introduction of anthracyline- and cytarabine-based regimens in the 1970s. Though some changes have been made in the dosing of anthracylines, in the choice of consolidation regimens versus allogeneic stem cell transplant, and in supportive care, clinical outcomes remain poor for most patients. As we continue to strive for better treatment options to improve upon outcomes, different agents, both chemotherapeutic and targeted therapies, are being studied. Here we discuss new chemotherapeutic agents that show promise in recent clinical trials and attempt to answer the question if there are any new effective cytotoxic chemotherapy agents out there.

// Giovanni Luca Gravina 1, 2 , Andrea Mancini 2 , Claudia Mattei 3 , Flora Vitale 3 , Francesco Marampon 2 , Alessandro Colapietro 2 , Giulia Rossi 2 , Luca Ventura 3 , Antonella Vetuschi 4 , Ernesto Di Cesare 1 , Judith A. Fox 5 , Claudio Festuccia 2 1 Department of Biotechnological and Applied Clinical Sciences, Division of Radiotherapy, University of L’Aquila, L’Aquila, Italy 2 Department of Biotechnological and Applied Clinical Sciences, Laboratory of Radiobiology, University of L’Aquila, L’Aquila, Italy 3 Department of Biotechnological and Applied Clinical Sciences, Laboratory of Neurosciences, University of L’Aquila, L’Aquila, Italy 4 Department of Biotechnological and Applied Clinical Sciences, Chair of Human Anatomy, University of L’Aquila, L’Aquila, Italy 5 Sunesis Pharmaceuticals Inc., South San Francisco, CA, USA Correspondence to: Claudio Festuccia, email: claudio.festuccia@univaq.it Keywords: glioblastoma, topoisomerase II, vosaroxin, double-strand breaks, radiotherapy Received: December 14, 2016 Accepted: March 03, 2017 Published: March 13, 2017 ABSTRACT Purpose: Glioblastoma multiforme (GBM) is the most aggressive brain tumor. The activity of vosaroxin, a first-in-class anticancer quinolone derivative that intercalates DNA and inhibits topoisomerase II, was investigated in GBM preclinical models as a single agent and combined with radiotherapy (RT). Results: Vosaroxin showed antitumor activity in clonogenic survival assays, with IC 50 of 10−100 nM, and demonstrated radiosensitization. Combined treatments exhibited significantly higher γH2Ax levels compared with controls. In xenograft models, vosaroxin reduced tumor growth and showed enhanced activity with RT; vosaroxin/RT combined was more effective than temozolomide/RT. Vosaroxin/RT triggered rapid and massive cell death with characteristics of necrosis. A minor proportion of treated cells underwent caspase-dependent apoptosis, in agreement with in vitro results. Vosaroxin/RT inhibited RT-induced autophagy, increasing necrosis. This was associated with increased recruitment of granulocytes, monocytes, and undifferentiated bone marrow–derived lymphoid cells. Pharmacokinetic analyses revealed adequate blood-brain penetration of vosaroxin. Vosaroxin/RT increased disease-free survival (DFS) and overall survival (OS) significantly compared with RT, vosaroxin alone, temozolomide, and temozolomide/RT in the U251-luciferase orthotopic model. Materials and Methods: Cellular, molecular, and antiproliferative effects of vosaroxin alone or combined with RT were evaluated in 13 GBM cell lines. Tumor growth delay was determined in U87MG, U251, and T98G xenograft mouse models. (DFS) and (OS) were assessed in orthotopic intrabrain models using luciferase-transfected U251 cells by bioluminescence and magnetic resonance imaging. Conclusions: Vosaroxin demonstrated significant activity in vitro and in vivo in GBM models, and showed additive/synergistic activity when combined with RT in O6-methylguanine methyltransferase-negative and -positive cell lines.

Background Vosaroxin is a first-in-class anticancer quinolone derivative that is being investigated for patients with relapsed or refractory acute myeloid leukemia (AML). The primary objective of this study was to quantitatively determine the pharmacokinetics of vosaroxin and its metabolites in patients with advanced solid tumors. Methods This mass balance study investigated the pharmacokinetics (distribution, metabolism, and excretion) of vosaroxin in cancer patients after a single dose of 60 mg/m2 14C–vosaroxin, administered as short intravenous injection. Blood, urine and feces were collected over 168 h after injection or until recovered radioactivity over 24 h was less than 1% of the administered dose (whichever was earlier). Total radioactivity (TRA), vosaroxin and metabolites were studied in all matrices. Results Unchanged vosaroxin was the major species identified in plasma, urine, and feces. N-desmethylvosaroxin was the only circulating metabolite detected in plasma, accounting for

The pharmacological therapy of non-promyelocytic acute myeloid leukemia (AML) has remained unchanged for over 40 years with an anthracycline–cytarabine combination forming the backbone of induction treatments. Nevertheless, the survival of younger patients has increased due to improved management of the toxicity of therapies including stem cell transplantation. Older patients and those with infirmity that precludes treatment-intensification have, however, not benefited from improvements in supportive care and continue to experience poor outcomes. An increased understanding of the genomic heterogeneity of AML raises the possibility of treatment-stratification to improve prognosis. Thus, efforts to identify agents with non-conventional anti-leukemic effects have paralleled those aiming to optimize leukemia cell-kill with conventional chemotherapy, resulting in a number of randomized controlled trials (RCT). In the last 18 months, RCTs investigating the effects of vosaroxin, azacitidine and gemtuzumab ozogamycin and daunorubicin dose have been reported with some studies indicating a statistically significant survival benefit with the investigational agent compared with standard therapy and potentially, a new era in AML therapeutics. Given the increasing costs of cancer care, a review of these studies, with particular attention to the magnitude of clinical benefit with the newer agents would be useful, especially for physicians treating patients in single-payer health systems.

Main purpose Voreloxin is a first-in-class anticancer quinolone derivative that intercalates DNA and inhibits topoisomerase II, inducing site-selective DNA damage. Voreloxin is in clinical studies, as a single agent and in combination with cytarabine, for the treatment of acute myeloid leukemia (AML). The preclinical studies reported here were performed to investigate the activity of voreloxin alone and in combination with cytarabine, in support of the clinical program. Research questions Is single agent voreloxin active in preclinical models of AML? Does the combination of voreloxin and cytarabine enhance the activity of either agent alone? Methods Inhibition of proliferation was studied in three cancer cell lines: HL-60 (acute promyelocytic leukemia), MV4-11 (AML), and CCRF-CEM (Acute lymphoblastic leukemia). Combination index (CI) analysis established the effect of the drugs in combination. A mouse model of bone marrow ablation was used to investigate in vivo efficacy of the drugs alone and in combination. Peripheral white blood cell and platelet counts were followed to assess marrow impact and recovery. Results Voreloxin and cytarabine alone and in combination exhibited cytotoxic activity in human leukemia cell lines and in vivo. The two drugs had additive or synergistic activity in vitro and supra-additive activity in vivo. Bone marrow ablation was accompanied by reductions in peripheral white blood cells and platelets that were reversible within 1 week, consistent with the AML treatment paradigm. Conclusions These data support ongoing clinical evaluation of voreloxin both alone and in combination with cytarabine for the treatment of AML.

Voreloxin, formerly known as SNS-595 or AG-7352, is a novel naphthyridine analog currently under investigation for the treatment of ovarian and hematologic malignancies. Voreloxin mechanism of action includes DNA intercalation and inhibition of topoisomerase II that causes selective DNA damage. In this study, we describe the anti-proliferative activity of voreloxin in a wide range of in vitro and in vivo models of human cancers.The cytotoxicity of voreloxin in vitro was examined by MTT assay in 15 cell lines, including 4 drug-resistant lines. Activation of caspase in cell lines and tumors was evaluated by immunohistochemistry. Anti-tumor activity was assessed in 16 xenograft and 3 syngeneic tumor models in mice. Tumors were allowed to grow to approximately 150 mm(3) prior to treatment with voreloxin or comparator drugs. Activity of the anti-cancer agents was determined by calculating the inhibition rate (IR = [1 - (average tumor weight treated/average tumor weight control)] x 100%) and survival ratio (number surviving mice/number of mice per group at start of study) for each agent and dose and schedule tested.In vitro studies demonstrated voreloxin has broad anti-proliferative activity in 11 tumor cell lines, with IC(50) values ranging from 0.04 to 0.97 muM. Similar activity was observed in vitro in drug-resistant cell lines, including those that overexpress P-glycoprotein and have reduced topoisomerase levels. After a single intravenous dose, voreloxin concentrations in tumor were correlated with induction of the apoptosis marker caspase-3. The optimal dose and schedule was established using a KB nasopharyngeal carcinoma xenograft model. Administration of voreloxin at 20 mg/kg weekly for five doses effectively inhibited tumor growth (86%). Voreloxin demonstrated strong dose-dependent tumor growth inhibition (63-88%) in 10 of 11 solid tumor (breast, ovarian, colon, lung, gastric, and melanoma) xenograft models, 2 hematologic tumor xenograft models, 3 multidrug resistant tumor models and 3 murine syngeneic tumor models (Colon 26, Lewis Lung carcinoma, M5076 Ovarian Sarcoma).These data demonstrate that voreloxin is a broadly active anti-tumor agent in vitro and in vivo, with potent activity in aggressive and drug-resistant tumor models.

More than half of the patients with acute myeloid leukaemia (AML) are older than 60years. The treatment outcomes in this group remain poor with a median overall survival of

Vosaroxin is a first-in-class anti-cancer quinolone that inhibits topoisomerase-II leading to cell cycle arrest and apoptosis. It has shown efficacy in a range of solid organ and haematopoietic tumours in vitro, and several clinical trials are underway or completed in the field of Acute Myeloid Leukaemia (AML). The treatment of relapsed and refractory AML is a clinical challenge, where long-term survival is rare without allogeneic haematopoietic stem cell transplantation.We review the data from the published clinical trials of vosaroxin, including the recently presented Phase III VALOR study. In combination with intermediate dose cytarabine, vosaroxin almost doubled complete response (CR) rates in relapsed and refractory AML compared with cytarabine alone, and prolonged median survival by 1.4 months.Vosaroxin is a promising new agent in the treatment of AML, with the potential to improve CR rates in a high-risk group of patients with relapsed and refractory AML. However, higher CR rates have been associated with higher rates of treatment-related morbidity and mortality, especially in elderly/unfit patients. Maximising the potential of vosaroxin will therefore require the identification of patients most likely to benefit from vosaroxin-containing combination regimens.

The development of new treatments for older patients with acute myeloid leukemia is an active area, but has met with limited success. Vosaroxin, a quinolone-derived intercalating agent has several properties that could prove beneficial. Initial clinical studies showed it to be well-tolerated in older patients with relapsed/refractory disease. In vitro data suggested synergy with cytarabine (Ara-C). To evaluate vosaroxin, we performed 2 randomized comparisons within the “Pick a Winner” program. A total of 104 patients were randomized to vosaroxin vs low-dose Ara-C (LDAC) and 104 to vosaroxin + LDAC vs LDAC. When comparing vosaroxin with LDAC, neither response rate (complete recovery [CR]/complete recovery with incomplete count recovery [CRi], 26% vs 30%; odds ratio [OR], 1.16 (0.49-2.72); P = .7) nor 12-month survival (12% vs 31%; hazard ratio [HR], 1.94 [1.26-3.00]; P = .003) showed benefit for vosaroxin. Likewise, in the vosaroxin + LDAC vs LDAC comparison, neither response rate (CR/CRi, 38% vs 34%; OR, 0.83 [0.37-1.84]; P = .6) nor survival (33% vs 37%; HR, 1.30 [0.81-2.07]; P = .3) was improved. A major reason for this lack of benefit was excess early mortality in the vosaroxin + LDAC arm, most obviously in the second month following randomization. At its first interim analysis, the Data Monitoring and Ethics Committee recommended closure of the vosaroxin-containing trial arms because a clinically relevant benefit was unlikely.

Acute myeloid leukemia (AML) is the second most common form of leukemia and the most frequent cause of leukemia-related deaths in the United States. The incidence of AML increases with advancing age and the prognosis for patients with AML worsens substantially with increasing age. Many older patients are ineligible for intensive treatment and require other therapeutic approaches to optimize clinical outcome. To address this treatment gap, novel agents with varying mechanisms of action targeting different cellular processes are currently in development. Hypomethylating agents (azacitidine, decitabine, SGI-110), histone deacetylase inhibitors (vorinostat, pracinostat, panobinostat), FMS-like tyrosine kinase receptor-3 inhibitors (quizartinib, sorafenib, midostaurin, crenolanib), cytotoxic agents (clofarabine, sapacitabine, vosaroxin), cell cycle inhibitors (barasertib, volasertib, rigosertib) and monoclonal antibodies (gentuzumab ozogamicin, lintuzumab-Ac225) represent some of these promising new treatments. This review provides an overview of novel agents that have either completed or are currently in ongoing phase III trials in patients with previously untreated AML for whom intensive treatment is not an option. Other potential drugs in earlier stages of development will also be addressed in this review.

Intermediate dose cytarabine (IDAC) defined by daily intravenous bolus of 1g/m² during 5 days has been recently defined as the standard control arm in phase 3 placebo-controlled randomized trials for patients with relapsed or refractory acute myeloid leukemia (R/R AML). In these trials assessing clofarabine/IDAC (CLASSIC-1 study, Faderl S et al., JCO 2012) or vosaroxin/IDAC (VALOR study, Ravandi F. et al., Lancet Oncol 2015) vs placebo/IDAC, complete remission rates and median overall survival with placebo/IDAC were 17.8%/18.9% and 6.3/6.1 months in the CLASSIC-1 and VALOR studies, respectively. However, the dose-intensity of this IDAC regimen remains questioned in routine practice since many centers still use higher doses of cytarabine often in combination with an anthracycline and a third drug including fludarabine, etoposide or gemtuzumab ozogamycin (FLAG-ida, MEC or MIDAM regimen for example) although these regimen have proved little efficacy and higher toxicity. We assessed the outcome of R/R AML patients that fulfilled main VALOR inclusion criteria consecutively treated in our center with intensive salvage regimen. All patients with a diagnosis of AML in first relapse or with refractory disease were eligible for this study. Acute promyelocytic leukemia were excluded. Relapse was defined as re-emergence of at least 5% leukemia blasts in bone marrow or at least 1% blasts in peripheral blood 90 days to 24 months after first complete remission or complete remission with incomplete platelet recovery. Refractory AML was defined as persistent disease at least 28 days after initiation of induction therapy, or relapse less than 90 days after first complete remission (CR) or CR with incomplete platelet recovery (CRi). All patients have received previous induction therapy with an anthracycline. Salvage regimen used were mainly cytarabine 3 g/m²/12h, d1-4 plus idarubicine 12 mg/m²/d, d1-3 or dauno 60 mg/m²/d, d1-2 or amsacrine 200 mg/m²/d, d1-3; less frequently MiDAM (mitoxantrone 12mg/m² d1-3, cytarabine1 g/m²/12h d1-5, GO 4-6mg/m², d4) or FLAG-Ida. Cytarabine dose for patients >60 was reduced to 1g/m²/12h, d1-5. We found, in our database, 151 R/R AML according to VALOR criteria treated between 2000 and 2013: 72 patients (48%) had refractory diseases (primary refractory: n=60, 40% and relapse less than 90 days after CR: n=12, 8.0%) and 79 (52%) had relapsed (early relapse more than 90 days after CR and less than one year: n=52, 66%; late relapse between one and two years: n=27, 34%). Patients characteristics were as follows: 85 (56%) were male, median age was 48 years (interquartile range [IQR], 36-60.5; 38 (27%) were 60 years or older). Cytogenetics at diagnosis was favorable in 18 (12%); intermediate in 93 (62%); adverse in 38 (25%) or unknown in 2 (1%) patients, respectively. They were treated as first line therapy with one (42%) or two cycles (58%). Early death rates at day 30 and day 60 were 7% and 17% in the whole cohort; 6% and 12% in younger patients and 12% and 29% in patients 60 years or older. Combined CR rate (defined as CR and CRi) was 53% for the whole cohort, and 57%/42%/56%/52%/63%/50% for Using VALOR inclusion criteria, age is the main factor that discriminate R/R AML patients selected for clinical trials using IDAC as control arm compared to patients of daily practice. Thus, those patient populations remain hardly comparable. However, as far as CR is concerned, IDAC seems suboptimal as compared to higher-intensity regimen used in daily practice. Yet, this higher CR rates do not translate into a significant gain in survival since median OS remains close to that of IDAC with the possible exception of refractory patients who seem to benefit from higher-intensity regimen. Thus, although unsatisfactory, IDAC could be considered as a fair control arm for overall survival endpoint especially in patients older than 60 year of age. Table Table. Disclosures Tavitian: Novartis: Membership on an entity's Board of Directors or advisory committees. Huguet:Pfizer, Novartis, BMS, Ariad, Jazz, Amgen: Membership on an entity's Board of Directors or advisory committees. Recher:Celgene, Sunesis, Amgen, Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene, Sunesis, Amgen, Novartis, Chugai: Research Funding.

Background: Prognosis for older patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) is poor, with lower response rates and shorter survival compared with younger patients. Vosaroxin is a first-in-class anticancer quinolone derivative that is active in AML, is minimally metabolized, evades P glycoprotein receptor-mediated efflux, and has activity independent of p53 status. In the phase 3 VALOR trial, overall survival (OS) was significantly improved with vosaroxin plus cytarabine vs placebo plus cytarabine in a prespecified analysis in patients ≥ 60 years of age (median OS: 7.1 mo vs 5.0 mo, respectively; HR = 0.75 [95% CI: 0.62-0.92]; P = 0.0030). At the time of the primary analysis (September 2014), patients had been followed for a median of 24.4 months (as estimated by the reverse Kaplan-Meier method). Here, after a median follow-up of 39.9 months, we provide updated survival information for patients ≥ 60 years treated in the VALOR trial. Methods: In VALOR, patients with refractory or first relapsed AML were randomized 1:1 to receive cytarabine (1 g/m2 IV over 2 h, d 1-5) plus either vosaroxin (90 mg/m2 IV over 10 min, d 1, 4; 70 mg/m2 in subsequent cycles) or placebo. Eligible patients had refractory disease (persistent disease after induction, or first complete remission [CR1] lasting < 90 d) or were in first relapse (early relapse: CR1 lasting 90 d to 12 mo; late relapse: CR1 lasting 12 mo to 24 mo). Randomization was stratified by age (< 60, ≥ 60 years), disease status (refractory, early relapse, late relapse), and geographic location (US, non-US). Patients were followed for survival until death. At the time of the primary analysis (September 2014), 63/451 (14%) patients ≥ 60 years were alive and in continued follow-up. Results:As of Jan 22, 2016, 33/451 patients ≥ 60 years treated in the VALOR trial were alive and in continued follow-up: 23/226 (10.2%) in the vosaroxin/cytarabine arm and 10/225 (4.4%) in the placebo/cytarabine arm. Updated OS data in patients ≥ 60 years of age was consistent with the primary analysis, demonstrating a significant improvement with the addition of vosaroxin (Figure; HR = 0.75 [95% CI: 0.62-0.91]; P = 0.0017). The survival benefit associated with vosaroxin/cytarabine was durable, as demonstrated by the separation of the survival curves through 48 mo. At 24 and 36 mo after randomization, the estimated survival rate was twice as high with vosaroxin/cytarabine as with placebo/cytarabine in patients ≥ 60 years (17.0% vs 8.5% and 12.8% vs 6.0%, respectively). The OS benefit was consistent across various age subgroups in the population ≥ 60 years of age; in patients 60-64 years (n = 124), 65-74 years (n = 293), and 75-84 years (n = 34), vosaroxin/cytarabine treatment increased median survival by 2.9 mo (8.1 vs 5.2 mo; HR = 0.72 [95% CI: 0.49-1.06]), 2.0 mo (7.0 vs 5.0 mo; HR = 0.76 [95% CI: 0.60-0.97]), and 2.2 mo (5.5 vs 3.3 mo; HR = 0.72 [95% CI: 0.36-1.45]) over placebo/cytarabine treatment, respectively. An improvement in OS was observed among patients ≥ 60 years who received post-treatment transplantation (n = 91; 19.9 mo with vosaroxin/cytarabine vs 12.2 mo with placebo/cytarbine; HR = 0.70 [95% CI: 0.43-1.13]) and those who did not (n = 360; 5.3 mo vs 3.8 mo, respectively; HR = 0.75 [95% CI: 0.60-0.92]). When analyzed by disease status, the greatest OS benefit was observed in patients ≥ 60 years with refractory disease (n = 210; 6.7 mo with vosaroxin/cytarabine vs 3.8 mo with placebo/cytarabine; HR = 0.75 [95% CI: 0.57-1.00]) and those with early relapse (n = 154; 6.5 mo vs 3.9 mo, respectively; HR = 0.62 [95% CI: 0.44-0.87]). In patients ≥ 60 years with late relapse (n = 87), median OS was similar in both treatment arms (9.2 mo with vosaroxin/cytarabine vs 9.8 mo with placebo/cytarabine; HR = 1.06 [95% CI: 0.68-1.66]). Conclusions: After a median of 39.9 months of follow-up in the VALOR trial, the OS observed in patients ≥ 60 years of age treated with vosaroxin/cytarabine remains significantly improved versus placebo/cytarabine, with a separation of the survival curves through 48 months. The OS benefit is consistent among all older patients, even those ≥ 75 years of age, and is seen in patients with and without post-treatment transplantation. The updated survival data from VALOR continue to support the use of vosaroxin/cytarabine as a treatment option in patients ≥ 60 years of age with R/R AML. Disclosures Ravandi: BMS: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Ritchie:Novartis: Honoraria, Research Funding; Celgene: Speakers Bureau; Incyte: Speakers Bureau; Pfizer: Honoraria; Arian: Speakers Bureau. Vey:Sunesis: Honoraria. Strickland:Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Schiller:Incyte Corporation: Research Funding. Jabbour:ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Erba:Ariad: Consultancy; Millennium Pharmaceuticals, Inc.: Research Funding; Celator: Research Funding; Novartis: Consultancy, Speakers Bureau; Amgen: Consultancy, Research Funding; Agios: Research Funding; Juno: Research Funding; Gylcomimetics: Other: DSMB; Astellas: Research Funding; Incyte: Consultancy, DSMB, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Consultancy; Sunesis: Consultancy; Jannsen: Consultancy, Research Funding. Pigneux:Agios: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria. Horst:Amgen, Novartis, Pfizer, Gilead, Agios: Consultancy; Amgen, Regeneron: Research Funding; Celgene: Honoraria. Recher:Celgene, Sunesis, Amgen, Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene, Sunesis, Amgen, Novartis, Chugai: Research Funding. Cortes:ARIAD: Consultancy, Research Funding; Bristol-Myers Squib: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding. Roboz:Agios, Amgen, Amphivena, Astex, AstraZeneca, Boehringer Ingelheim, Celator, Celgene, Genoptix, Janssen, Juno, MEI Pharma, MedImmune, Novartis, Onconova, Pfizer, Roche/Genentech, Sunesis, Teva: Consultancy; Cellectis: Research Funding. Craig:Sunesis: Employment, Equity Ownership. Ward:Sunesis Pharmaceuticals: Consultancy, Employment. Smith:Sunesis: Employment, Equity Ownership. Stuart:Agios: Research Funding; Sunesis: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding; Incyte: Research Funding; Bayer: Research Funding; Celator: Research Funding; Astellas: Research Funding.

Background. AML blasts from different patients vary in the agents to which they are most responsive. With a plethora of novel agents to evaluate, there is a lack of predictive biomarkers to precisely assign targeted therapies to individual patients. Primary AML cells often survive poorly in vitro, thus confounding conventional cytotoxicity assays. Dynamic profiling, i.e. functional biomarker assays of responsiveness to chemotherapeutic agents, is an alternative approach to help further the move towards personalised therapy. The purpose of this work was to assess the potential of two same-day dynamic profiling assays in AML cell lines to predict response to chemotherapy. (i) Ribosomal protein S6 (rpS6) is a downstream substrate of PI3K/akt/mTOR/ p70S6 kinase and MAPK/p90S6 kinase pathways and is also dephosphorylated following DNA double strand breaks. It thus has the potential to function as a biomarker of responsiveness to several therapeutic agents. (ii) Cellular propensity for apoptosis can be interrogated via a functional assay termed BH3 profiling. Dynamic BH3 profiling can be used to predict cellular responses to therapy based on priming mitochondria with BH3 domain peptides and thus allowing early detection of pro-apoptotic drug effects on mitochondrial outer membrane permeabilisation. Methods.We measured effects of a short (four hour) incubation with drugs of interest on rpS6 phosphorylation and BH3 peptide-accelerated cytochrome C release by flow cytometry. Baseline rpS6 phosphorylation was determined by culture with the mTOR inhibitor Rapamycin and the MEK inhibitor U0126. BH3 profiling included permeabilisation with digitonin followed by mitochondrial exposure to PUMA BH3-derived peptide. To establish specificity for sensitive cells we also measured dose responses to the drugs in 12 diverse AML cell lines after 48 hours' culture. Results. RpS6 dephosphorylation at four hours closely predicted the 48 hour IC50 for FLT3 inhibitors, an hsp90 inhibitor and topoisomerase II inhibitors. ROC (predictive test) analysis of small molecule inhibitors showed that the assay was highly sensitive and specific with area under the curve (AUC) values of 1.0 (sorafenib), 1.0 (AC220) and 1.0 (17-AAG). RpS6 phosphorylation also predicted response to the double strand break inducing drugs, with AUC values of 1.0 (mylotarg), 0.83 (etoposide) and 0.82 (vosaroxin). In contrast, responses to cytarabine and ABT-199, likely independent of mTOR, MAPK or double strand break response pathways, are not predicted by rpS6 dephosphorylation. PUMA-BH3 peptide-induced cytochrome C release also closely predicted the 48 hour IC50 with AUC values for FLT3 inhibitors of 1.0 (sorafenib) and 1.0 (AC220), double strand break inducing drugs 1.0 (mylotarg), 1.0 (etoposide) and 1.0 (vosaroxin) and a Bcl-2 targeting agent 0.875 (ABT-199). Response to 17-AAG and cytarabine were not predicted by this assay. Preliminary analysis shows that differential responses within primary AML sample subsets can be interrogated with these methodologies. Conclusions. In conclusion, we have established that rpS6 dephosphorylation and/or PUMA-BH3 peptide-induced cytochrome C release predict chemoresponsiveness to tyrosine kinase inhibitors, topoisomerase II inhibitors, an hsp90 inhibitor and a Bcl-2 targeting agent in AML cell lines after short term culture. Both assays are sensitive, specific and amenable to leukaemic sub-population analysis and are thus suitable assays for further development towards use in a clinical setting. pRS6 can be performed on smaller samples and is less technically challenging than priming with PUMA-BH3 peptide, but does not take into account apoptosis resistance that may occur independently of pathways effecting pRS6 inhibition. Disclosures No relevant conflicts of interest to declare.

The antineoplastic quinolone derivative vosaroxin (SNS-595, Sunesis, South San Francisco, CA, USA) was first described in 2002. It represents a novel class of anticancer drugs and is currently in a Phase III clinical trial for relapsed and refractory acute myeloid leukemia (AML). AML is the most common form of acute leukemia in adults and is increasing in incidence due to the aging of the American population. Despite advances in diagnosis, prognostic prediction, and treatment in younger age groups, there has been little improvement in survival among patients over 60 years of age, who make up the majority of those affected.The development of vosaroxin, its mechanism of action, pharmacology, and metabolism, and the preclinical and clinical data to date will be covered.Despite its structural dissimilarity, vosaroxin has mechanisms of action similar to the anthracyclines and anthracenediones already in use for the treatment of AML. However, unlike these agents, vosaroxin is not a P-gp substrate, appears to be unaffected by overexpression of P-gp or TP53 mutations, and may be useful in the treatment of AML, especially in the elderly.

Purpose Vosaroxin is a first in class naphthyridine analog structurally related to quinolone antibacterials, that intercalates DNA and inhibits topoisomerase II. Vosaroxin is not a P-glycoprotein receptor substrate and its activity is independent of p53, thus evading common drug resistance mechanisms. To evaluate vosaroxin as a clinically applicable radiation sensitizer, we investigated its effects on tumor cell radiosensitivity in vitro and in vivo. Methods Vosaroxin's effect on post-irradiation sensitivity of U251, DU145, and MiaPaca-2 cells was assessed by clonogenic assay. Subsequent mechanistic and in vivo studies were performed with U251 cells. Cell cycle distribution and G2 checkpoint integrity was analyzed by flow cytometry. DNA damage and repair was evaluated by a high throughput gamma-H2AX assay. Apoptosis was assessed by flow cytometry. Mitotic catastrophe was assessed by microscopic evidence of fragmented nuclei by immunofluorescence. In vivo radiosensitization was measured by subcutaneous tumor growth delay. Results 50-100 nmol/L treatment with vosaroxin resulted in radiosensitization of all 3 cell lines tested with a dose enhancement factor of 1.20 to 1.51 measured at a surviving fraction of 0.1. The maximal dose enhancement was seen in U251 cells treated with 75 nmol/L vosaroxin (DEF 1.51). Vosaroxin exposure did not change cell cycle distribution prior to irradiation nor alter G2 checkpoint integrity after irradiation. No difference was seen in the apoptotic fraction regardless of drug or radiation treatment. The number of cells in mitotic catastrophe was significantly greater in irradiated cells treated with vosaroxin than cells receiving radiation only at 72 hr (p = 0.009). Vosaroxin alone did not significantly increase mitotic catastrophe over control (p = 0.53). Cells treated with vosaroxin and radiation maintained significantly higher gamma-H2AX levels than cells treated with vehicle control (p = 0.014), vosaroxin (p = 0.042), or radiation alone (p = 0.039) after 24 hr. In vivo tumor growth delay was 1.5 days for vosaroxin alone (IV 10 mg/kg), 1.0 days for radiation (3 Gy) alone, and 8.6 days for the group treated with vosaroxin 4 hours prior to radiation. Conclusions Vosaroxin enhanced tumor cell radiosensitivity in vitro and in vivo. The mechanism appears to be related to inhibition of DNA repair and increased mitotic catastrophe.

Background: Topoisomerase II is essential for the maintenance of DNA integrity and the survival of proliferating cells. Topoisomerase II poisons, including etoposide and doxorubicin, inhibit enzyme-mediated DNA ligation causing the accumulation of double-stranded breaks and have been front-line drugs for the treatment of leukemia for many years. Voreloxin is a first-in-class anti-cancer quinolone derivative that intercalates DNA and inhibits topoisomerase II. The efficacy and mechanisms of action of voreloxin in acute myeloid leukaemia were addressed in this study. Design and Methods: Primary acute myeloid leukemia blasts (n = 88) and myeloid cell lines were used in vitro to study voreloxin through viability assays to assess cell killing and synergy with other drugs. Apoptosis and cell cycling were assessed by flow cytometry. DNA relaxation assays were utilized to determine that voreloxin was active on topoisomerase II. Results: The mean lethal dose 50% (LD50) (± standard deviation) of voreloxin for primary acute myeloid leukemia blasts was 2.30 μM (± 1.87). Synergy experiments between voreloxin and cytarabine identified synergism in 22 of 25 primary acute myeloid leukemia samples tested, with a mean combination index of 0.79. Apoptosis was shown to increase in a dose-dependent manner. Furthermore, voreloxin was active in the p53-null K562 cell line suggesting that the action of voreloxin is not affected by p53 status. The action of voreloxin on topoisomerase II was confirmed using a DNA relaxation assay. Conclusions: Voreloxin may provide an interesting addition to the cache of drugs available for the treatment of acute myeloid leukemia, a disease with a poor long-term survival. In addition to its potent action as a single agent in dividing cells, the synergy we demonstrated between voreloxin and cytarabine recommends further investigation of this topoisomerase II inhibitor.