Protein-bound molybdenum cofactor is bioavailable and rescues molybdenum cofactor-deficient C. elegans.

The molybdenum cofactor (Moco) is a 520-Da prosthetic group that is synthesized in all domains of life. In animals, four oxidases (among them sulfite oxidase) use Moco as a prosthetic group. Moco is essential in animals; humans with mutations in genes that encode Moco biosynthetic enzymes display lethal neurological and developmental defects. Moco supplementation seems a logical therapy; however, the instability of Moco has precluded biochemical and cell biological studies of Moco transport and bioavailability. The nematode Caenorhabditis elegans can take up Moco from its bacterial diet and transport it to cells and tissues that express Moco-requiring enzymes, suggesting a system for Moco uptake and distribution. Here we show that protein-bound Moco is the stable, bioavailable species of Moco taken up by C. elegans from its diet and is an effective dietary supplement, rescuing a Celegans model of Moco deficiency. We demonstrate that diverse Moco:protein complexes are stable and bioavailable, suggesting a new strategy for the production and delivery of therapeutically active Moco to treat human Moco deficiency.

Phase 1 dose escalation trial of volasertib in combination with decitabine in patients with acute myeloid leukemia.

Polo-like kinase 1 (PLK1) regulates mitotic checkpoints and cell division. PLK1 overexpression is reported in numerous cancers, including acute myeloid leukemia (AML), and is associated with poor prognosis. Volasertib is a selective, potent cell-cycle kinase inhibitor that targets PLK to induce mitotic arrest and apoptosis. This phase 1 trial investigated the maximum tolerated dose (MTD), safety, pharmacokinetics, and anti-leukemic activity of volasertib in combination with decitabine in AML patients aged ≥ 65 years. Thirteen patients were treated with escalating volasertib doses (3 + 3 design; 300 mg, 350 mg, and 400 mg) plus standard-dose decitabine. Dose-limiting toxicity was reported in one patient in cycle 1; the MTD of volasertib in combination with decitabine was determined as 400 mg. The most common treatment-emergent adverse events were febrile neutropenia, pneumonia, and decreased appetite. Objective response rate was 23%. The combination was well tolerated, and the adverse event profile was in line with previous findings.

Calibrated liposomal release of the anti-mitotic agent BI-2536 increases the targeting of mitotic tumor cells.

Cancer drugs which are specifically targeted at mitosis have generally under-delivered as a class. One likely reason is that only a small percentage of cancer cells in a tumor are actually dividing at any moment. If this is the case, then prolonged bioavailability in the tumor should significantly increase the efficacy of antimitotic agents. Here, we show that if the Plk1 inhibitor BI 2536 is co-encapsulated in a liposome with a pair of anions, its release rate is dependent on both the identity and stoichiometry of the anions. We created a library of liposomes with varying release rates using this approach and found that liposomal drug release rates correlated inversely with in vitro cancer cell killing. Xenografted mice treated with a single dose of slow-releasing liposomal BI 2536 experienced tumor volume decreases lasting 12 days and complete responses in 20% of mice. Treatment with two doses a week apart increased the response rate to 75%. This approach, which we termed Paired Anion Calibrated Release (PACeR), has the potential to revive the clinical utility of antimitotic cancer drugs which have failed clinical trials.

Phase I dose-escalation study of volasertib in pediatric patients with acute leukemia or advanced solid tumors.

BACKGROUND: Volasertib induces mitotic arrest and apoptosis by targeting Polo-like kinases. In this phase I dose-escalation study, the maximum tolerated dose (MTD), pharmacokinetics (PK), and preliminary efficacy of volasertib were determined in pediatric patients. METHODS: Patients aged 2 to <18 years with relapsed/refractory acute leukemia/advanced solid tumors (ST) without available effective treatments were enrolled-cohort C1 (aged 2 to <12 years); cohort C2 (aged 12 to <18 years). The patients received volasertib intravenously (starting dose: 200 mg/m2 body surface area on day 1, every 14 days). The primary endpoint was the pediatric MTD for further development. RESULTS: Twenty-two patients received treatment (C1: leukemia, n = 4; ST, n = 8; C2: leukemia, n = 3; ST, n = 7). No dose-limiting toxicities (DLTs) occurred up to 300 mg/m2 volasertib in C1; two patients in C2, at 250 mg/m2 volasertib, had DLTs in cycle 1, one of which led to death; therefore, the MTD of volasertib in C2 was 200 mg/m2 . The most common grade 3/4 adverse events (all patients) were febrile neutropenia, thrombocytopenia, and neutropenia (41% each). Stable disease (SD) was the best objective response (leukemia, n = 5; ST, n = 2); the duration of SD was short in all patients, except in one with an ST. PK profiles were generally comparable across dose groups and were consistent with those in adults. CONCLUSION: The pediatric MTD/dose for further development was identified. There were no unexpected safety or PK findings; limited antitumor/antileukemic activity was demonstrated.

Sorafenib-loaded hydroxyethyl starch-TG100-115 micelles for the treatment of liver cancer based on synergistic treatment.

Tumor microenvironment is closely related to the occurrence and development of liver cancer. Tumor-associated macrophages (TAMs) are an important part of tumor microenvironment promoting tumor deterioration and metastasis by inhibiting immune cells. Previous studies showed that PI3Kγ inhibitor could reverse the phenotype of TAMs, relieve immunosuppression and sensitize chemotherapy drugs, suggesting that the combination of PI3Kγ inhibitor and chemotherapeutics is likely to bring new breakthroughs in the treatment of liver cancer. Based on it, this paper builds HES-TG100-115-CDM-PEG micelles with tumor microenvironment responsiveness that simultaneously loaded sorafenib and TG100-115 to synergistically treat liver cancer. Pharmacokinetic study showed that the prepared micelles had longer half-life than that of the free drug solutions, which was favorable for high propensity of extravasation through tumor vascular fenestrations. Under low pH and high α-amylasereductive conditions, micelles could depolymerize quickly due to the sensitivity of bonds and enhance significantly cytotoxic activity against Hep-3B liver cancer cell. Additionally, micelles demonstrated higher levels of antitumor efficiency and better tolerance against nude mouse with Hep-3B cell than the free drug solutions. These findings reveal that HES-TG100-115-CDM-PEG micelles are a promising drug delivery system in clinical comprehensive therapy of liver cancer.

Metabolism of vesatolimod in rat, dog, and human liver microsomes: Metabolic stability assessment, metabolite identification, and interspecies comparison.

Vesatolimod (GS-9620) is an agonist of toll-like receptor (TLR7) 7, which has been developed as an anti-hepatitis B virus (HBV) agent. The focus of the present study is on the metabolic stability evaluation and metabolite identification of GS-9620 in rat, dog, and human liver microsomes, as well as interspecies comparison. The average observed in vitro T1/2 values were 3.06, 13.06, and 15.56 minutes in rat, dog, and human liver microsomes, respectively. The findings suggested that GS-9620 was rapidly metabolized in the presence of reductive nicotinamide adenine dinucleotide phosphate (NADPH) in rat liver microsomes (RLM), and moderately metabolized in dog liver microsomes (DLM) and human liver microsomes (HLM). Subsequently, the metabolites were characterized using an ultra-high performance liquid chromatography coupled with linear ion trap orbitrap tandem mass spectrometer (UHPLC-LTQ-Orbitrap-MS) with dd-MS2 on-line data acquisition mode. Under the current conditions, a total of 18 metabolites were detected and their identities were proposed by comparing their accurate masses, fragmental ions, and retention times with those of GS-9620. Three metabolites (M2, M4, and M18) were authentically identified by using reference standards. In RLM, 16 metabolites were identified with M2 being the most abundant metabolite. M4, M5, and M9 were rat-specific. In DLM, 12 minor metabolites were identified with a dog-specific metabolite (M6). In HLM, GS-9620 showed similar metabolic profiles to that in DLM, and 11 minor metabolites were detected with M12 being human-specific. Based on the identified metabolites, the metabolic pathways of GS-9620 were proposed, including hydroxylation, bis-hydroxylation, dehydrogenation, and oxidative deamination.

Kinetics of drosopterin release as indicator pigment for heat-induced color changes of brown shrimp (Crangon crangon).

Heat-induced color changes of crustaceans are commonly described as the release of astaxanthin. In this study on Crangon crangon, it was found that astaxanthin plays a minor role in the (dis)coloration. By LC-HRMS, two polar, process dependent pigments were found. One pigment was identified as riboflavin and one as drosopterin (level-2 certainty). Thermal treatments had highest effect on drosopterin concentration changes and were chosen as indicator for a kinetic study of heat-induced color changes. The kinetic data fitted a consecutive step model (r2 = 0.971), including a first step in which drosopterin was released (kd,85°C = 0.95 ±â€¯0.09 min-1; Ead = 105 ±â€¯4 kJ/mol) and a second step where drosopterin is degraded (kb,85°C = 0.02 ±â€¯0.002 min-1; Eab = 190 ±â€¯15 kJ/mol). The kinetic model shows that shrimp should be heated at lower temperatures (<80 °C) than the heating temperatures used by fishermen (86-101 °C), creating opportunities for quality optimization. Therefore, this study delivers essential information needed in a comprehensive quality optimization study of the cooked brown shrimp.

Safety, efficacy and pharmacodynamics of vesatolimod (GS-9620) in virally suppressed patients with chronic hepatitis B.

BACKGROUND & AIMS: Vesatolimod (GS-9620) is an oral agonist of toll-like receptor 7, an activator of innate and adaptive immune responses. Herein the safety and efficacy of vesatolimod is assessed after once-weekly treatment in patients with chronic hepatitis B (CHB) infection suppressed on oral antiviral treatment. METHODS: In a phase II, double-blind, randomized, placebo (PBO)-controlled study, 162 patients stratified by hepatitis B surface antigen (HBsAg) levels and serum hepatitis B e antigen (HBeAg) status were randomized 1:3:3:3 to once-weekly oral PBO or vesatolimod (1-, 2-, or 4-mg doses) for 4, 8 or 12 weeks per cohort. Efficacy was assessed by change in baseline HBsAg (log10 IU/ml) at the primary endpoint (Week 24). Safety assessments included adverse events (AE) and laboratory abnormality monitoring. Pharmacodynamic assessments included peripheral cytokine level quantification and interferon-stimulated gene (ISG) mRNA expression evaluation. RESULTS: The majority of patients were male (76%) and HBeAg-negative (79%) at baseline. Most (41-80%) experienced ≥1 AE during the study with the majority of AEs mild or moderate in severity. No significant declines in HBsAg were observed at the primary (Week 24) or secondary endpoints (Weeks 4, 8, 12, and 48). ISG15 induction was dose-dependent and consistent after repeat dosing, returning closer to baseline by one week after treatment at all dose levels; no patient demonstrated significant serum interferon alpha (IFNα) expression at any timepoint evaluated. Multivariate analyses showed that ≥2-fold ISG15 induction is associated with 2- or 4-mg vesatolimod dose and female sex. CONCLUSIONS: Vesatolimod was safe and well-tolerated in patients with CHB, demonstrating consistent dose-dependent pharmacodynamic induction of ISG15 without significant systemic induction of IFNα expression or related symptoms. However, no significant HBsAg declines were observed. LAY SUMMARY: In a phase II study, vesatolimod, an oral, once-weekly, experimental immune-activating drug for the treatment of hepatitis B virus (HBV), is safe and well-tolerated in chronic HBV patients who are virally suppressed on oral antiviral treatment. Despite demonstrating on-target biomarker responses in patients, no significant declines in hepatitis B surface antigen were observed. Clinical Trial Number: GS-US-283-1059; NCT 02166047.

Population Pharmacokinetics of Volasertib Administered in Patients with Acute Myeloid Leukaemia as a Single Agent or in Combination with Cytarabine.

BACKGROUND: Volasertib, a potent and selective polo-like kinase inhibitor, has shown to increase response rates and improve survival with a clinically manageable safety profile, administered alone and in combination with cytarabine in patients with acute myeloid leukaemia. OBJECTIVES: The objectives of this analysis were to describe the pharmacokinetics of volasertib and cytarabine, administered as single agents or in combination. METHODS: Three thousand, six hundred and six plasma volasertib concentrations from 501 patients receiving either volasertib alone, or in combination with cytarabine, and 826 plasma cytarabine concentrations from 650 patients receiving cytarabine as multiple subcutaneous injections per cycle either alone, or in combination with volasertib, were analysed using NONMEM Version 7.3. Covariates evaluated included demographic and disease-related parameters. RESULTS: The pharmacokinetics of volasertib were found to be dose independent from 150 to 550 mg. Body surface area and ethnicity showed significant effects in all the patients. This is reflected as an increase in drug exposure for Japanese patients, although this finding has to be interpreted with caution because only 7% of patients were part of that population group. Volasertib showed low-to-mild inter-individual variability in total clearance. For the case of cytarabine, its pharmacokinetics was affected by body surface area. Finally, volasertib and cytarabine did not influence the pharmacokinetic characteristics of each other. CONCLUSIONS: The pharmacokinetics of volasertib in patients with acute myeloid leukaemia alone or in combination with cytarabine is predictable and associated with low-to-mild patient variability with the exception of the high variability associated with the volume of distribution of the central compartment, having no effect on the area under the plasma concentration-time curve.

Phase I trial of volasertib, a Polo-like kinase inhibitor, in Japanese patients with advanced solid tumors.

PURPOSE: This trial evaluated the maximum tolerated dose (MTD), safety, pharmacokinetics, and clinical effects of volasertib, a selective Polo-like kinase inhibitor that induces mitotic arrest and apoptosis, in Japanese patients with advanced solid tumors (NCT01348347; 1230.15). METHODS: In this phase I, open-label, dose-escalation trial, sequential patient cohorts (3 + 3 dose-escalation design) received volasertib (200-350 mg) as a single dose by intravenous infusion over 2 h on day 1 every 21 days until disease progression or unacceptable toxicity. The primary endpoint was the MTD of volasertib in Japanese patients with an advanced solid tumor; secondary endpoints included safety, pharmacokinetics, and clinical benefit. RESULTS: Fifteen patients with an advanced solid tumor were treated. Dose-limiting toxicities of grade 4 neutropenia for ≥7 days and grade 4 thrombocytopenia were both experienced by 2/6 patients in the 350 mg cohort. The MTD of volasertib in Japanese patients was 300 mg. The most common (≥3 patients) drug-related non-hematologic adverse events included fatigue, decreased appetite, and nausea. Exposure to volasertib and its metabolite increased with increasing doses. A partial response in a patient with gastric cancer and stable disease in eleven patients were observed. CONCLUSIONS: Volasertib had a manageable safety profile up to the MTD determined as 300 mg. Exposure to volasertib and its metabolite increased with increasing doses. The safety profile of volasertib in Japanese patients is comparable with those previously obtained in Caucasian patients. These data support enrollment of Japanese patients in global clinical trials without dose modification.

Phase I trial of volasertib, a Polo-like kinase inhibitor, in Japanese patients with acute myeloid leukemia.

This phase I trial conducted in Japanese patients with acute myeloid leukemia evaluated the safety, maximum tolerated dose and pharmacokinetics of volasertib (BI 6727), a selective Polo-like kinase inhibitor. The primary endpoints were the maximum tolerated dose of volasertib and the incidence of dose-limiting toxicities. Secondary endpoints were best response and remission duration. Other endpoints included safety and pharmacokinetics. Patients who were ineligible for standard induction therapy or with relapsed or refractory disease received volasertib monotherapy as a 2-h infusion on days 1 and 15 of a 28-day cycle, with dose escalation following a 3 + 3 design. A total of 19 patients were treated with three volasertib doses: 350, 400 and 450 mg. One patient receiving volasertib 450 mg reported a dose-limiting toxicity of grade 4 abnormal liver function test and 450 mg was determined as the maximum tolerated dose. The most frequently reported adverse events were febrile neutropenia (78.9%), decreased appetite (42.1%), nausea and rash (36.8% each), and sepsis, fatigue, hypokalemia, stomatitis and epistaxis (26.3% each). Best responses were complete remission (n = 3), complete remission with incomplete blood count recovery (n = 3) and partial remission (n = 1). The median remission duration of the six patients with complete remission or complete remission with incomplete blood count recovery was 85 days (range 56-358). Volasertib exhibited multi-compartmental pharmacokinetic behavior with a fast distribution after the end of infusion followed by slower elimination phases. Volasertib monotherapy was clinically manageable with acceptable adverse events and anti-leukemic activity.

A phase I study of volasertib combined with afatinib, in advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose (MTD) of volasertib, a Polo-like kinase inhibitor, combined with afatinib, an oral irreversible ErbB family blocker, in patients with advanced solid tumors (NCT01206816; Study 1230.20). METHODS: Patients with advanced non-resectable and/or metastatic disease following failure of conventional treatment received intravenous volasertib 150-300 mg on day 1 every 21 days, combined with oral afatinib 30-40 mg on days 2-21 of a 3-week cycle (Schedule A), or 50-90 mg on days 2-6 of a 3-week cycle (Schedule B). The primary objective was to determine the MTD of volasertib in combination with afatinib. RESULTS: Fifty-seven patients (Schedule A, N = 29; Schedule B, N = 28) were treated. The MTDs were volasertib 300 mg plus afatinib 30 mg days 2-21 and 70 mg days 2-6 of a 3-week cycle for Schedules A and B, respectively. The most common Grade 3/4 adverse events were neutropenia (31.0 %), diarrhea (13.8 %), and thrombocytopenia (10.3 %) in Schedule A; neutropenia (39.3 %), thrombocytopenia (35.7 %), hypokalemia (14.3 %), febrile neutropenia, and nausea (each 10.7 %) in Schedule B. The best overall response was two partial responses (6.9 %; both in Schedule A); eight patients in each schedule achieved stable disease. Volasertib showed multi-exponential pharmacokinetic (PK) behavior; co-administration of volasertib and afatinib had no significant effects on the PK profile of either drug. CONCLUSIONS: Volasertib combined with afatinib had manageable adverse effects and limited antitumor activity in this heavily pretreated population.

The oral toll-like receptor-7 agonist GS-9620 in patients with chronic hepatitis B virus infection.

BACKGROUND & AIMS: GS-9620 is an oral agonist of toll-like receptor 7, a pattern-recognition receptor whose activation results in innate and adaptive immune stimulation. We evaluated the safety, pharmacokinetics, and pharmacodynamics of GS-9620 in patients with chronic hepatitis B. METHODS: In two double-blind, phase 1b trials of identical design, 49 treatment-naïve and 51 virologically suppressed patients were randomized 5:1 to receive GS-9620 (at doses of 0.3mg, 1mg, 2mg, 4mg) or placebo as a single dose or as two doses seven days apart. Pharmacodynamic assessment included evaluation of peripheral mRNA expression of interferon-stimulated gene 15 (ISG15), serum interferon gamma-induced protein 10 and serum interferon (IFN)-alpha. RESULTS: Overall, 74% of patients were male and 75% were HBeAg negative at baseline. No subject discontinued treatment due to adverse events. Fifty-eight percent experienced ⩾1 adverse event, all of which were mild to moderate in severity. The most common adverse event was headache. No clinically significant changes in HBsAg or HBV DNA levels were observed. Overall, a transient dose-dependent induction of peripheral ISG15 gene expression was observed peaking within 48 hours of dosing followed by return to baseline levels within seven days. Higher GS-9620 dose, HBeAg positive status, and low HBsAg level at baseline were independently associated with greater probability of ISG15 response. Most patients (88%) did not show detectable levels of serum IFN-alpha at any time point. CONCLUSIONS: Oral GS-9620 was safe, well tolerated, and associated with induction of peripheral ISG15 production in the absence of significant systemic IFN-alpha levels or related symptoms.

Phase I trial of volasertib, a Polo-like kinase inhibitor, plus platinum agents in solid tumors: safety, pharmacokinetics and activity.

BACKGROUND: This trial evaluated the maximum tolerated dose (MTD), safety, pharmacokinetics, and activity of volasertib, a selective Polo-like kinase 1 inhibitor that induces mitotic arrest and apoptosis, combined with cisplatin or carboplatin in patients with advanced/metastatic solid tumors (NCT00969761; 1230.6). METHODS: Sequential patient cohorts (3 + 3 dose-escalation design) received a single infusion of volasertib (100-350 mg) with cisplatin (60-100 mg/m(2)) or carboplatin (area under the concentration versus time curve [AUC]4-AUC6) on day 1 every 3 weeks for up to six cycles. Sixty-one patients received volasertib/cisplatin (n = 30) or volasertib/carboplatin (n = 31) for a median of 3.5 (range, 1-6) and 2.0 (range, 1-6) treatment cycles, respectively. RESULTS: The most common cycle 1 dose-limiting toxicities (DLTs) were thrombocytopenia, neutropenia and fatigue. MTDs (based on cycle 1 DLTs) were determined to be volasertib 300 mg plus cisplatin 100 mg/m(2) and volasertib 300 mg plus carboplatin AUC6. Co-administration did not affect the pharmacokinetics of each drug. Partial responses were observed in two patients in each arm. Stable disease was achieved in 11 and six patients treated with volasertib/cisplatin and volasertib/carboplatin, respectively. CONCLUSIONS: Volasertib plus cisplatin or carboplatin at full single-agent doses was generally manageable and demonstrated activity in heavily pretreated patients with advanced solid tumors.

Sustained efficacy and seroconversion with the Toll-like receptor 7 agonist GS-9620 in the Woodchuck model of chronic hepatitis B.

BACKGROUND & AIMS: New therapies for chronic hepatitis B (CHB) are urgently needed since current treatments rarely lead to cure. We evaluated whether the oral small molecule toll-like receptor (TLR7) agonist GS-9620 could induce durable antiviral efficacy in woodchucks chronically infected with woodchuck hepatitis virus (WHV), a hepadnavirus closely related to human hepatitis B virus (HBV). METHODS: After evaluating the pharmacokinetics, pharmacodynamics and tolerability of oral GS-9620 in uninfected woodchucks, adult woodchucks chronically infected with WHV (n = 7 per group) were dosed with GS-9620 or placebo for 4 or 8 weeks with different treatment schedules. RESULTS: GS-9620 treatment induced rapid, marked and sustained reduction in serum viral DNA (mean maximal 6.2log10 reduction), and hepatic WHV DNA replicative intermediates, WHV cccDNA and WHV RNA, as well as loss of detectable serum WHV surface antigen (WHsAg). GS-9620 treatment also induced a sustained antibody response against WHsAg in a subset of animals. Strikingly, treatment reduced the incidence of hepatocellular carcinoma (HCC) from 71% in the placebo group to 8% in GS-9620-treated woodchucks with sustained viral load reduction. GS-9620 treatment was associated with reversible increases in serum liver enzymes and thrombocytopenia, and induced intrahepatic CD8(+) T cell, NK cell, B cell and interferon response transcriptional signatures. CONCLUSIONS: The data demonstrate that short duration, finite treatment with the oral TLR7 agonist GS-9620 can induce a sustained antiviral response in the woodchuck model of CHB, and support investigation of this compound as a therapeutic approach to attain a functional cure in CHB patients.

Safety, pharmacokinetics and pharmacodynamics of the oral toll-like receptor 7 agonist GS-9620 in treatment-naive patients with chronic hepatitis C.

BACKGROUND: GS-9620 is a potent oral agonist of toll-like receptor 7, a key modulator of the innate immune response. In healthy volunteers, low doses of GS-9620 (2, 4 and 6 mg) induced significant expression of peripheral interferon-stimulated-gene (ISG) mRNA in the absence of detectable serum interferon-α and systemic adverse events (AEs). We evaluated the safety, pharmacokinetics and pharmacodynamics of GS-9620 in treatment-naive patients chronically infected with HCV genotype 1. METHODS: In this double-blind, placebo-controlled study, 51 patients were randomized 5:1 (active:placebo) to receive either a single dose or two once-weekly doses of GS-9620 at four dose levels (0.3, 1, 2 and 4 mg) or placebo. Pharmacodynamic assessments included peripheral ISG15 mRNA expression, serum interferon-α and interferon-γ-inducible protein (IP)-10 levels and HCV RNA quantification. RESULTS: GS-9620 was well-tolerated at all doses. Most AEs were mild or moderate in severity. GS-9620 exhibited dose-linear pharmacokinetics with a median half-life in plasma of 18 h. Transient, dose-dependent ISG15 induction was observed at 1, 2 and 4 mg, with peak mean fold change within 48 h followed by a decline to baseline levels within 7 days of dosing. Serum interferon-α induction post-baseline was detected in 16.7% (8/48) of patients. No clinically significant reductions in HCV RNA were observed. CONCLUSIONS: GS-9620 was safe, well-tolerated and biologically active in patients with HCV infection. Induction of ISG15 occurred in the absence of detectable serum interferon-α or systemic AEs in most patients, supporting a pre-systemic mechanism of action. ClinicalTrials.gov identifier: NCT01591668.

Randomized, phase 2 trial of low-dose cytarabine with or without volasertib in AML patients not suitable for induction therapy.

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.

A phase I study of two dosing schedules of volasertib (BI 6727), an intravenous polo-like kinase inhibitor, in patients with advanced solid malignancies.

BACKGROUND: Polo-like kinase 1 (Plk1) has an important role in mitosis. Volasertib (BI 6727), a potent and selective cell cycle kinase inhibitor, induces mitotic arrest and apoptosis by targeting Plk; this phase I study sought to determine its maximum tolerated dose (MTD) in Asian patients with advanced solid tumours. METHODS: Patients were enrolled simultaneously into two 3-week schedules of volasertib: a 2-h infusion on day 1 (schedule A) or days 1 and 8 (schedule B). Dose escalation followed a 3+3 design. The MTD was determined based on dose-limiting toxicities (DLT) in the first treatment course. RESULTS: Among 59 treated patients, the most common first course DLTs were reversible thrombocytopenia, neutropenia and febrile neutropenia; MTDs were 300 mg for schedule A and 150 mg for schedule B. Volasertib exhibited multi-exponential pharmacokinetics (PK), a long terminal half-life of ∼135 h, a large volume of distribution (>3000 l), and a moderate clearance. Partial responses were observed in two pre-treated patients (ureteral cancer; melanoma). Volasertib was generally well tolerated, with an adverse event profile consistent with its antimitotic mode of action and a favourable PK profile. CONCLUSIONS: These data support further development of volasertib and a harmonised dosing for Asian and Caucasian patients.

Overcoming resistance to Sonic Hedgehog inhibition by targeting p90 ribosomal S6 kinase in pediatric medulloblastoma.

BACKGROUND: Molecular subtyping has allowed for the beginning of personalized treatment in children suffering from medulloblastoma (MB). However, resistance inevitably emerges against these therapies, particularly in the Sonic Hedgehog (SHH) subtype. We found that children with SHH subtype have the worst outcome underscoring the need to identify new therapeutic targets. PROCEDURE: High content screening of a 129 compound library identified agents that inhibited SHH MB growth. Lead molecular target levels, p90 ribosomal S6 kinase (RSK) were characterized by immunoblotting and qRT-PCR. Comparisons were made to human neural stem cells (hNSC). Impact of inhibiting RSK with the small molecule BI-D1870 or siRNA was assessed in growth assays (monolayer, neurosphere, and soft agar). NanoString was used to detect RSK in a cohort of 66 patients with MB. To determine BI-D1870 pharmacokinetics/pharmacodynamics, 100 mg/kg was I.P. injected into mice and tissues were collected at various time points. RESULTS: Daoy, ONS76, UW228, and UW426 MB cells were exquisitely sensitive to BI-D1870 but unresponsive to SHH inhibitors. Anti-tumor growth corresponded with inactivation of RSK in MB cells. BI-D1870 had no effect on hNSCs. Inhibiting RSK with siRNA or BI-D1870 suppressed growth, induced apoptosis, and sensitized cells to SHH agents. Notably, RSK expression is correlated with SHH patients. In mice, BI-D1870 was well-tolerated and crossed the blood-brain barrier (BBB). CONCLUSIONS: RSK inhibitors are promising because they target RSK which is correlated with SHH patients as well as cause high levels of apoptosis to only MB cells. Importantly, BI-D1870 crosses the BBB, acting as a scaffold for development of more long-lived RSK inhibitors.

Initial testing (stage 1) of the Polo-like kinase inhibitor volasertib (BI 6727), by the Pediatric Preclinical Testing Program.

BACKGROUND: Volasertib (BI 6727) is a potent inhibitor of Polo-like kinase 1 (Plk1), that is overexpressed in several childhood cancers and cell lines. Because of its novel mechanism of action, volasertib was evaluated through the PPTP. PROCEDURES: Volasertib was tested against the PPTP in vitro cell line panel at concentrations from 0.1 nM to 1.0 µM and against the PPTP in vivo xenograft panels administered IV at a dose of 30 mg/kg (solid tumors) or 15 mg/kg (ALL models) using a q7dx3 schedule. RESULTS: In vitro volasertib demonstrated cytotoxic activity, with a median relative IC50 value of 14.1 nM, (range 6.0-135 nM). Volasertib induced significant differences in EFS in 19 of 32 (59%) of the evaluable solid tumor xenografts and in 2 of 4 (50%) of the evaluable ALL xenografts. Volasertib induced tumor growth inhibition meeting criteria for intermediate EFS T/C (>2) activity in 11 of 30 (37%) evaluable solid tumor xenografts, including neuroblastoma (4 of 6) and glioblastoma (2 of 3) panels, and 2 of 4 ALL models. Objective responses (CR's) were observed for 4 of 32 solid tumor (two neuroblastoma, one glioblastoma, and one rhabdomyosarcoma) and one of four ALL xenografts. CONCLUSIONS: Volasertib shows potent in vitro activity against the PPTP cell lines with no histotype selectivity. In vivo, volasertib induced regressions in several xenograft models. However, pharmacokinetic data suggest that mice tolerate higher systemic exposure to volasertib than humans, suggesting that the current results may over-estimate potential clinical efficacy against the childhood cancers studied.