Oral paclitaxel and encequidar in patients with breast cancer: a pharmacokinetic, safety, and antitumor activity study.

Background: Paclitaxel is widely used for the treatment of metastatic breast cancer (MBC). However, it has a low oral bioavailability due to gut extrusion caused by P-glycoprotein (P-gp). Oral paclitaxel (oPAC) may be more convenient, less resource-intensive, and more tolerable than its intravenous form. Encequidar (E) is a first-in-class, minimally absorbed, gut-specific oral P-gp inhibitor that facilitates the oral absorption of paclitaxel. Objectives: To investigate the pharmacokinetics (PK), overall response rate (ORR), and safety of weekly oral paclitaxel with encequidar (oPAC + E) in patients with advanced breast cancer. Design: This is a multicenter, single-arm, open-label study in six medical centers in Taiwan. Methods: Patients with advanced breast cancer were administered 205 mg/m2 oPAC and 12.9 mg E for 3 consecutive days weekly for up to 16 weeks. Plasma samples were collected at weeks 1 and 4. PK, ORR, and safety were evaluated. Results: In all, 28 patients were enrolled; 27 had MBC; 23 had prior chemotherapy; and 14 had ⩾2 lines of prior chemotherapy. PK were evaluable in 25 patients. Plasma paclitaxel area under the curve (AUC)(0-52 h) at week 1 (3419 ± 1475 ng h/ml) and week 4 (3224 ± 1150 ng h/ml) were equivalent. Best overall response in 28 evaluable patients was partial response (PR) in 11 (39.3%), 13 (46.4%) stable disease (SD), and 1 (3.6%) with progressive disease (PD). No patient achieved complete response (CR). The clinical benefit rate (CR + PR + SD) was 85.7%. Major adverse events among the 28 treated patients were grade 3 neutropenia (25%), grade 4 neutropenia (18%), with febrile neutropenia in 4%, and grade 3 diarrhea (4%). No treatment-related deaths occurred. Grade 2 peripheral neuropathy occurred in 1 (4%) patient and grade 3 peripheral neuropathy in 1 (4%) patient. Conclusions: oPAC + E produced a consistent therapeutic plasma paclitaxel exposure during treatment. There was a high rate of radiologically assessed clinical benefit, and a low rate of neurotoxicity which may provide advantages over IV paclitaxel. Registration: ClinicalTrials.gov Identifier: NCT03165955.

Oxide Metallurgy Technology in High Strength Steel: A Review.

Oxide metallurgy technology plays an important role in inclusion control and is also applied to improve the weldability of high strength steel. Based on the requirements of the weldability in high strength steel, the influencing factors of weld heat affected zone (HAZ) as well as the development and application status of oxide metallurgy technology are summarized in this review. Moreover, the advantages and difficulties in the application of rare earth (RE) oxide metallurgy technology are analyzed, combined with the performance mechanism of RE and its formation characteristics of fine and high melting point RE inclusions with distribution dispersed in liquid steel. With the weldability diversities of different high strength steels, the research status of weldability of high strength steel with high carbon equivalent and the effects of RE on the microstructure and properties of HAZ are discussed, and some suggestions about further research in the future are proposed.

Effect of Cerium on the Microstructure and Inclusion Evolution of C-Mn Cryogenic Vessel Steels.

The effects of Cerium (Ce) were studied on the casting slab quality, microstructure, and inclusion evolution of cryogenic vessel steel. An optical metallographic microscope, scanning electron microscope, energy dispersive spectrometer, and Thermo-calc thermodynamic software were used for characterization and analysis. The results indicated that the central segregation was significantly improved after adding Ce and reached the lowest level when the content of Ce was 0.0009 wt.%. Meanwhile, the presence of Ce reduces the size of ferrite and improves pearlite morphology. Ce also enables the modification of Al2O3 and MnS + Ti4C2S2 inclusions into ellipsoid CeAlO3 and spherical Ce2O2S + Ti4C2S2 composite inclusions, respectively, which are easier to remove. The formed Ce2O2S inclusions are fine and can work as heterogeneous nucleation points to refine the microstructure of steel.

A Phase 1 study of RO6870810, a novel bromodomain and extra-terminal protein inhibitor, in patients with NUT carcinoma, other solid tumours, or diffuse large B-cell lymphoma.

BACKGROUND: Bromodomain and extra-terminal (BET) proteins are epigenetic readers that can drive carcinogenesis and therapy resistance. RO6870810 is a novel, small-molecule BET inhibitor. METHODS: We conducted a Phase 1 study of RO6870810 administered subcutaneously for 21 or 14 days of 28- or 21-day cycles, respectively, in patients with the nuclear protein of the testis carcinoma (NC), other solid tumours, or diffuse large B-cell lymphoma (DLBCL) with MYC deregulation. RESULTS: Fatigue (42%), decreased appetite (35%) and injection-site erythema (35%) were the most common treatment-related adverse events. Pharmacokinetic parameters demonstrated linearity over the dose range tested and support once-daily dosing. Pharmacodynamic assessments demonstrated sustained decreases in CD11b levels in peripheral blood mononuclear cells. Objective response rates were 25% (2/8), 2% (1/47) and 11% (2/19) for patients with NC, other solid tumours and DLBCL, respectively. Responding tumours had evidence of deregulated MYC expression. CONCLUSIONS: This trial establishes the safety, favourable pharmacokinetics, evidence of target engagement and preliminary single-agent activity of RO6870810. Responses in patients with NC, other solid tumours and DLBCL provide proof-of-principle for BET inhibition in MYC-driven cancers. The results support further exploration of RO6870810 as monotherapy and in combinations. CLINICAL TRIALS REGISTRATION: NCT01987362.

Murine double minute 2 inhibition alone or with cytarabine in acute myeloid leukemia: Results from an idasanutlin phase 1/1b study⋆.

The prognosis remains poor for patients with relapsed or refractory (r/r) acute myeloid leukemia; thus, novel therapies are needed. We evaluated idasanutlin-a new, potent murine double minute 2 antagonist-alone or with cytarabine in patients with r/r acute myeloid leukemia, de novo untreated acute myeloid leukemia unsuitable for standard treatment or with adverse features, or secondary acute myeloid leukemia in a multicenter, open-label, phase 1/1b trial. Primary objectives were to determine the maximum tolerated dose (MTD) and recommended dose for expansion (RDE) and characterize the safety profile of idasanutlin monotherapy and combination therapy. Clinical activity and pharmacokinetics were secondary objectives. Two idasanutlin formulations were investigated: a microprecipitate bulk powder (MBP) and optimized spray-dried powder (SDP). Following dose escalation, patients (N = 122) received idasanutlin at the RDE in the extension cohorts. No formal MTD was identified. Idasanutlin was tolerable alone and in combination with cytarabine. The RDE was determined as 600 mg twice a day for the MBP formulation and 300 mg twice a day for the SDP formulation. Adverse events were mostly grade 1/2 (76.2 %). The most common any-grade adverse events were gastrointestinal (including diarrhea [90.2 %]). The early death rate across all patients was 14.8 %. Plasma idasanutlin exposure was dose related. In TP53 wild-type patients, composite complete remission rates were 18.9 % with monotherapy and 35.6 % with combination therapy. Based on these results, idasanutlin development continued with further investigation in the treatment of acute myeloid leukemia. ClinicalTrials.gov: NCT01773408.

A single-center, open-label study investigating the excretion balance, pharmacokinetics, metabolism, and absolute bioavailability of a single oral dose of [14C]-labeled idasanutlin and an intravenous tracer dose of [13C]-labeled idasanutlin in a single cohort of patients with solid tumors.

PURPOSE: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic p53 activator with oral administration. To determine the need to conduct dedicated trial(s) for organ impairment on pharmacokinetic (PK) exposure and/or drug-drug interactions, a single dose of [14C]- and [13C]-labeled idasanutlin was evaluated. METHODS: This study was an open-label, non-randomized, single-center trial of idasanutlin to investigate the excretion balance, pharmacokinetics, metabolism, and absolute bioavailability of a single oral dose of [14C]-labeled idasanutlin and an IV tracer dose of [13C]-labeled idasanutlin in a single cohort of patients with solid tumors. After completing cycle 1 assessments, patients could have participated in an optional treatment extension of idasanutlin. Clinical endpoints were PK, and safety/tolerability. RESULTS: Co-administration of an oral dose of idasanutlin with an IV tracer dose revealed low systemic CL, a moderate Vd, and a moderate (40.1%) absolute bioavailability of idasanutlin. Idasanutlin and its major inactive metabolite, M4, were the major circulating moieties in plasma, and excretion of idasanutlin-associated radioactivity was primarily via the fecal route (91.5% of the dose), with negligible amounts recovered in urine, following oral administration. CONCLUSION: The clinical implications of this study support the conclusion that renal impairment is unlikely to significantly impact exposure to idasanutlin and M4 metabolite, whereas a significant hepatic impairment may potentially alter exposure to the parent drug and/or metabolite(s). The potential for drug-drug interactions is low.

Lack of UGT polymorphism association with idasanutlin pharmacokinetics in solid tumor patients.

PURPOSE: Idasanutlin is a selective small-molecule MDM2 antagonist. It activates the tumor suppressor TP53 and is in phase 3 clinical trial for acute myeloid leukemia. Nonclinical studies have shown that glucuronidation is the major metabolizing mechanism for idasanutlin and UGT1A3 is the major metabolizing enzyme. There are reported examples of UGT polymorphisms associated with drug metabolism or response. Thus, the aim of this analysis is to investigate if UGT polymorphism is associated with idasanutlin pharmacokinetics. METHOD: Idasanutlin clearance was derived and normalized from two phase I studies. Its clearance level was compared between patients with different genotypes at 44 non-monomorphic UGT SNPs. Several single-locus and multi-locus association analysis, including haplotype association analysis and pairwise SNP interaction (epistasis) analyses were performed to investigate if there is any association between UGT genotypes and idasanutlin clearance. RESULTS AND CONCLUSION: A total of 69 patients who have both idasanutlin pharmacokinetic data and UGT genotyping data were analyzed for association. The major clearance enzyme for idasanutlin, UGT1A3, has no association with idasanutlin clearance. Further single-locus and multi-locus association analyses also suggest that no significant UGT polymorphism association with idasanutlin clearance can be detected with the current datasets. However, the possibility of association with rare allele(s) of UGT family genes cannot be excluded due to the limited sample size of the current phase I studies.

Phase 1 summary of plasma concentration-QTc analysis for idasanutlin, an MDM2 antagonist, in patients with advanced solid tumors and AML.

PURPOSE: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. The aim of this analysis is to examine the potential of idasanutlin to prolong the corrected QT (QTc) interval by evaluating the relationship between plasma idasanutlin concentration and QTc interval. METHOD: Intensive plasma concentration QTc interval data were collected at the same timepoints, from three idasanutlin (RO5503781) phase 1 studies in patients with solid tumors and AML. QTc data in absolute values and changes from baseline (Δ) were analyzed for a potential association with plasma idasanutlin concentrations with a linear mixed effect model. Categorical analysis was also performed. RESULTS: A total of 282 patients were exposed to idasanutlin and had at least one observation of QTc and idasanutlin plasma concentration. There was no apparent increase of QTcF or ΔQTcF in a wide idasanutlin plasma concentration range, even at concentrations exceeding the exposure matching the dose adopted in the ongoing phase 3 study (300-mg BID). Categorical analysis did not detect a potential signal of QT prolongation. CONCLUSION: The concentration-QTc analysis indicates that idasanutlin does not prolong the QT interval within the targeted concentration range currently in consideration for clinical development.

Effects of posaconazole (a strong CYP3A4 inhibitor), two new tablet formulations, and food on the pharmacokinetics of idasanutlin, an MDM2 antagonist, in patients with advanced solid tumors.

PURPOSE: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. To optimize its dosing conditions, a number of clinical pharmacology characteristics were examined in this multi-center trial in patients with advanced solid tumors. METHOD: This was an open-label, single-dose, crossover clinical pharmacology study investigating the effects of strong CYP3A4 inhibition with posaconazole (Part 1), two new oral formulations (Part 2), as well as high-energy/high-fat and low-energy/low-fat meals (Part 3) on the relative bioavailability of idasanutlin. After completing Part 1, 2, or 3, patients could have participated in an optional treatment with idasanutlin. Clinical endpoints were pharmacokinetics (PK), pharmacodynamics (PD) of MIC-1 elevation (Part 1 only), and safety/tolerability. RESULTS: The administration of posaconazole 400 mg BID × 7 days with idasanutlin 800 mg resulted in a slight decrease (7%) in Cmax and a modest increase (31%) in AUC for idasanutlin, a marked reduction in Cmax (~ 60%) and AUC0 (~ 50%) for M4 metabolite, and a minimal increase (~ 24%) in serum MIC-1 levels. Cmax and AUC were both 45% higher for the SDP formulation. While the low-fat meal caused a less than 20% increase in all PK exposure parameters with the 90% CI values just outside the upper end of the equivalence criteria (80-125%), the high-fat meal reached bioequivalence with dosing under fasting. CONCLUSION: In patients with solid tumors, multiple doses of posaconazole, a strong CYP3A4 inhibitor, minimally affected idasanutlin PK and PD without clinical significance. The SDP formulation improved rBA/exposures by ~ 50% without major food effect.

An apparent clinical pharmacokinetic drug-drug interaction between bevacizumab and the anti-placental growth factor monoclonal antibody RO5323441 via a target-trapping mechanism.

PURPOSE: RO5323441 is a humanized anti-placental growth factor (PlGF) monoclonal antibody that has shown preclinical activity in several cancer models. The objective of this analysis is to examine the pharmacokinetic (PK) results from four Phase I studies that have been conducted with RO5323441 (n = 61) and to report an apparent drug-drug interaction observed when RO5323441 was administered in combination with bevacizumab. METHODS: The four Phase I studies were a multiple-ascending dose study in 23 patients with solid tumors (Study 1), an open-label study in seven patients with colorectal/ovarian cancer (Study 2), a sorafenib combination study in nine patients with hepatocellular carcinoma (Study 3), and a bevacizumab combination study in 22 patients with recurrent glioblastoma (Study 4). A two-compartment linear population PK model was developed from these four studies to characterize the PK of RO5323441 in patients with cancer. RESULTS: The PK properties of RO5323441 were similar in the first three studies. However, substantially higher RO5323441 exposures were observed in Study 4 when RO5323441 was administered in combination with bevacizumab. A linear two-compartmental population PK model indicated that the co-administration of bevacizumab would decrease the clearance of RO5323441 by 53%. Clinical data suggested that the decrease in RO5323441 clearance was inversely associated with bevacizumab exposure. CONCLUSIONS: The exact reason for the increase in RO5323441 exposure following bevacizumab co-administration is not currently known. One possibility is a drug-drug interaction via a target-trapping mechanism that is mediated by the vascular endothelial growth factor receptor-1 (VEGFR-1).

Dose-Dependent Effect of Piragliatin, a Glucokinase Activator, on the QT Interval Following Short-Term Multiple Doses in Patients With Type 2 Diabetes Mellitus.

To determine the effect of piragliatin on the QTcS (QT-corrected study-specific) interval, a double-blind, double-dummy, placebo-controlled, active-comparator, 4-period, 4-treatment, 4-sequence randomized crossover trial was performed in 42 patients with type 2 diabetes mellitus who received 100 and 200 mg piragliatin twice daily, placebo, and 400 mg moxifloxacin (on day 1 and day 5 only) for 5 days. In the categorical analyses, piragliatin did not have a clinically significant effect on the QTcS interval at either dose, and the majority of patients were categorized with low risk for maximum change from baseline (≤30 milliseconds) and a maximum postbaseline QTcS interval as normal (≤450 milliseconds). However, in the analysis of variance model, both piragliatin doses crossed the 10-millisecond threshold (100 mg twice daily on day 5, hour 1; 200 mg twice daily on days 1 and 5, hours 1 and 2) with P values indicating statistical significance. Headache and mild hypoglycemia were the most frequent adverse events associated with piragliatin treatment. There appeared that the effect of piragliatin treatment on the QTc interval was dose/exposure dependent following short-term multiple doses. Longer-term monitoring of electrocardiograms with pharmacokinetic exposure should continue, especially at conditions for potentially higher pharmacokinetic exposure.

Investigating the effect of autoinduction in cynomolgus monkeys of a novel anticancer MDM2 antagonist, idasanutlin, and relevance to humans.

1. Idasanutlin (RG7388) is a potent p53-MDM2 antagonist currently in clinical development for treatment of cancer. The purpose of the present studies was to investigate the cause of marked decrease in plasma exposure after repeated oral administration of RG7388 in monkeys and whether the autoinduction observed in monkeys is relevant to humans. 2. In monkey liver and intestinal microsomes collected after repeated oral administration of RG7388 to monkeys, significantly increased activities of homologue CYP3A8 were observed (ex vivo). Investigation using a physiologically based pharmacokinetic (PBPK) model suggested that the loss of exposure was primarily due to induction of metabolism in the gut of monkeys. 3. Studies in monkey and human primary hepatocytes showed that CYP3A induction by RG7388 only occurred in monkey hepatocytes but not in human hepatocytes, which suggests the observed CYP3A induction is monkey specific. 4. The human PK data obtained from the first cohorts confirmed the lack of relevant induction as predicted by the human hepatocytes and the PBPK modelling based on no induction in humans.

Exploratory effects of a strong CYP3A inhibitor (ketoconazole), a strong CYP3A inducer (rifampicin), and concomitant ethanol on piragliatin pharmacokinetics and pharmacodynamics in type 2 diabetic patients.

Piragliatin is a CYP3A substrate; its inactive metabolite M4, formed through cytosolic reductase, is reversibly metabolized back to piragliatin through CYP3A. The impact of concomitant CYP3A modifiers thus cannot be predicted. Drinking alcohol under fasting conditions is associated with a recognized glucose-lowering effect, which might be synergistic with piragliatin's hypoglycemic effect. Two exploratory studies were conducted to examine these potential interactions in type 2 diabetes (T2D) patients: 16 completed an open-label, sequential 2-way crossover, 2-arm (randomized to ketoconazole and rifampicin) CYP3A study; another 18 participated in a double-blind, placebo-controlled, randomized 3-way crossover ethanol study. Administration of piragliatin (100-mg single dose) resulted in a 32% Cmax and 44% area under the curve (AUC∞ ) increase in piragliatin exposure without affecting glucose AUC0-6h following ketoconazole (400 mg QD × 5 days); 30% Cmax and 72% AUC∞ decrease in piragliatin exposure with a 13% increase in glucose AUC0-6h following rifampicin (600 mg QD × 5 days); and, unexpectedly, a 32% Cmax and 23% AUC0-6h decrease (no change in AUC∞ ) in piragliatin exposure with a 13% increase in glucose AUC0-6h following alcohol (40-g single dose). In conclusion, a strong CYP3A modifier or concomitant alcohol could lead to a change in exposure to piragliatin with a potential alteration in glucose-lowering effect.

Effects of piragliatin, a glucokinase activator, on fasting and postprandial plasma glucose in patients with type 2 diabetes mellitus.

To assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of piragliatin, a double-blind, randomized, placebo-controlled, multiple-ascending-doses study was conducted in patients with type 2 diabetes mellitus (T2D). Fifty-nine T2D patients were given piragliatin or placebo in a dose-escalation design as a single dose on day 1 followed by multiple doses on days 3 through 8 at doses of 10, 25, 50, 100, and 200 mg twice a day (BID) as well as 200 mg every day (QD). Blood and urine samples were collected for PK analysis. PD assessments included plasma glucose, insulin, C-peptide, glucagon, and GLP-1. Piragliatin exposure was dose proportional without appreciable accumulation or food effect. Piragliatin treatment at steady state yielded dose-dependent reductions up to 32.5% and 35.5% for the highest dose in fasting and postprandial plasma glucose. Piragliatin was well tolerated. Mild or moderate hypoglycemia with rapid recovery after sugar-containing drinks or scheduled meals was the only dose-limiting adverse event. It is concluded that multiple doses of piragliatin consistently showed rapid, dose-dependent glucose reduction of fasting and postprandial plasma glucose in T2D patients.

Lack of Potential Pharmacokinetic and Pharmacodynamic Interactions Between Piragliatin, a Glucokinase Activator, and Simvastatin in Patients With Type 2 Diabetes Mellitus.

To evaluate the potential pharmacokinetic (PK) and pharmacodynamic (PD, glucose-lowering effect) interaction between simvastatin and piragliatin, both CYP3A substrates, 30 patients with type 2 diabetes mellitus participated in this open-label, randomized, 6-sequence, 3-way crossover (William's design) study. During 3 periods, patients were randomized to receive a single dose of 80 mg simvastatin alone, a single dose of 100 mg piragliatin alone, as well as single doses of 80 mg simvastatin and 100 mg piragliatin together. Primary PK and PD parameters were AUCs on dosing days. The ratio of geometric means (90% confidence intervals) of the AUCinf of piragliatin coadministered with simvastatin compared with piragliatin alone was 0.98 (0.92-1.05), whereas that of the AUCinf of simvastatin acid (active metabolite) coadministered with piragliatin compared with simvastatin alone, was 1.02 (0.90-1.16), suggesting lack of pharmacokinetic interaction between piragliatin and simvastatin. Piragliatin's glucose-lowering effect was not affected by coadministration of simvastatin. Overall, administration of piragliatin with simvastatin was without additional clinically relevant adverse effects as well as abnormality in laboratory tests, vital signs, and electrocardiogram parameters. Concomitant administration of simvastatin and piragliatin, both CYP3A substrates, has no clinically relevant effect on the pharmacokinetics of either piragliatin or simvastatin or on the pharmacodynamics for piragliatin.

Results of the Phase I Trial of RG7112, a Small-Molecule MDM2 Antagonist in Leukemia.

PURPOSE: RG7112 is a small-molecule MDM2 antagonist. MDM2 is a negative regulator of the tumor suppressor p53 and frequently overexpressed in leukemias. Thus, a phase I study of RG7112 in patients with hematologic malignancies was conducted. EXPERIMENTAL DESIGN: Primary study objectives included determination of the dose and safety profile of RG7112. Secondary objectives included evaluation of pharmacokinetics; pharmacodynamics, such as TP53-mutation status and MDM2 expression; and preliminary clinical activity. Patients were divided into two cohorts: Stratum A [relapsed/refractory acute myeloid leukemia (AML; except acute promyelocytic leukemia), acute lymphoblastic leukemia, and chronic myelogenous leukemia] and Stratum B (relapsed/refractory chronic lymphocytic leukemia/small cell lymphocytic leukemia; CLL/sCLL). Some Stratum A patients were treated at the MTD to assess clinical activity. RESULTS: RG7112 was administered to 116 patients (96 patients in Stratum A and 20 patients in Stratum B). All patients experienced at least 1 adverse event, and 3 dose-limiting toxicities were reported. Pharmacokinetic analysis indicated that twice-daily dosing enhanced daily exposure. Antileukemia activity was observed in the 30 patients with AML assessed at the MTD, including 5 patients who met International Working Group (IWG) criteria for response. Exploratory analysis revealed TP53 mutations in 14% of Stratum A patients and in 40% of Stratum B patients. Two patients with TP53 mutations exhibited clinical activity. p53 target genes were induced only in TP53 wild-type leukemic cells. Baseline expression levels of MDM2 correlated positively with clinical response. CONCLUSIONS: RG7112 demonstrated clinical activity against relapsed/refractory AML and CLL/sCLL. MDM2 inhibition resulted in p53 stabilization and transcriptional activation of p53-target genes. We provide proof-of-concept that MDM2 inhibition restores p53 function and generates clinical responses in hematologic malignancies.

Clinical pharmacology characterization of RG7112, an MDM2 antagonist, in patients with advanced solid tumors.

PURPOSE: RG7112, the first selective small-molecule MDM2 antagonist in clinical testing, is a non-genotoxic oral p53 activator. To optimize its dose and schedule, a number of clinical pharmacology characteristics were explored in this multicenter trial in patients with advanced solid tumors. METHOD: In part 1, the impact of high-energy/high-fat meal and formulations (crystalline and amorphous) on relative bioavailability was examined in single-dose crossover designs. In part 2, schedule optimization (4 schedules of drug administration under fasting condition and 2 cohorts with liquid supplementation) was investigated in parallel, dose escalation designs. Clinical endpoints were pharmacokinetics (PK), pharmacodynamics (PD) including MIC-1 elevation and platelet reduction, and safety/tolerability. RESULTS: With a single-dose treatment, a high-fat/high-energy meal and a new formulation under fasting condition, respectively, enhanced overall bioavailability of RG7112 slightly over twofold. Following multiple-dose administrations, all four schedules yielded the comparable per-cycle (28-d) exposure (AUC), as designed; liquid supplements also enhanced bioavailability. High-dose treatments of consecutive daily dosing for 5 and 3 days resulted in higher on-treatment-day exposure to RG7112 than both weekly and low-dose/long-duration (20-day) daily schedules. Serum MIC-1 and blood platelet profiles showed similar patterns to those of PK when the clinical pharmacology conditions were varied, suggesting the relative importance of treatment-day exposure than overall per-cycle AUC. CONCLUSION: Food (both high-fat and low-fat meals) and new formulation enhanced bioavailability. High-dose consecutive daily treatment for 3-5 days is superior to weekly and low-dose/long-duration (20-day) daily schedules in yielding the sufficiently high drug exposure and PD effects potentially required for cancer treatment efficacy.

Effect of the MDM2 antagonist RG7112 on the P53 pathway in patients with MDM2-amplified, well-differentiated or dedifferentiated liposarcoma: an exploratory proof-of-mechanism study.

BACKGROUND: We report a proof-of-mechanism study of RG7112, a small-molecule MDM2 antagonist, in patients with chemotherapy-naive primary or relapsed well-differentiated or dedifferentiated MDM2-amplified liposarcoma who were eligible for resection. METHODS: Patients with well-differentiated or dedifferentiated liposarcoma were enrolled at four centres in France. Patients received up to three 28-day neoadjuvant treatment cycles of RG7112 1440 mg/m(2) per day for 10 days. If a patient progressed at any point after the first cycle, the lesion was resected or, if unresectable, an end-of-study biopsy was done. The primary endpoint was to assess markers of RG7112-dependent MDM2 inhibition and P53 pathway activation (P53, P21, MDM2, Ki-67, macrophage inhibitory cytokine-1 [MIC-1], and apoptosis). All analyses were per protocol. This trial is registered with EudraCT, number 2009-015522-10. RESULTS: Between June 3, and Dec 14, 2010, 20 patients were enrolled and completed pretreatment and day 8 biopsies. 18 of 20 patients had TP53 wild-type tumours and two carried missense TP53 mutations. 14 of 17 assessed patients had MDM2 gene amplification. Compared with baseline, P53 and P21 concentrations, assessed by immunohistochemistry, had increased by a median of 4·86 times (IQR 4·38-7·97; p=0·0001) and 3·48 times (2·05-4·09; p=0·0001), respectively, at day 8 (give or take 2 days). At the same timepoint, relative MDM2 mRNA expression had increased by a median of 3·03 times (1·23-4·93; p=0·003) that at baseline. The median change from baseline for Ki-67-positive tumour cells was -5·05% (IQR -12·55 to 0·05; p=0·01). Drug exposure correlated with blood concentrations of MIC-1 (p<0·0001) and haematological toxicity. One patient had a confirmed partial response and 14 had stable disease. All patients experienced at least one adverse event, mostly nausea (14 patients), vomiting (11 patients), asthenia (nine patients), diarrhoea (nine patients), and thrombocytopenia (eight patients). There were 12 serious adverse events in eight patients, the most common of which were neutropenia (six patients) and thrombocytopenia (three patients). DISCUSSION: MDM2 inhibition activates the P53 pathway and decreases cell proliferation in MDM2-amplified liposarcoma. This study suggests that it is feasible to undertake neoadjuvant biopsy-driven biomarker studies in liposarcoma. FUNDING: F Hoffmann-La Roche.

Population pharmacokinetics of rituximab in patients with chronic lymphocytic leukemia.

This retrospective analysis characterizes rituximab population pharmacokinetics in combination with fludarabine and cyclophosphamide and its effect on fludarabine and cyclophosphamide disposition in chronic lymphocytic leukemia (CLL) patients. Rituximab concentration data were well described by a 2-compartment model comprising a time-varying clearance component related to the target-mediated clearance pathway and a constant clearance component reflecting catabolic elimination pathway. Marked differences were observed compared to pharmacokinetic parameters for non-Hodgkin lymphoma (NHL) obtained previously: in CLL, time-varying clearance at time zero (CL(2)) was faster, volumes of distribution (V(1) and V(2)) were larger, and rate of change (K(des)) from the targetmediated clearance pathway to catabolic elimination was lower than NHL. Fludarabine and cyclophosphamide disposition showed no apparent change when co-administered with rituximab. A positive correlation between pharmacokinetic parameters and clinical response was observed, supporting the use of the higher rituximab dose of 500 mg/m(2) in CLL patients (vs 375 mg/m(2) in NHL) to achieve an effective clinical response.