PK Exposure Research Articles

Atazanavir increases the plasma concentrations of 1200 mg raltegravir dose

Raltegravir is a human immunodeficiency virus (HIV)-1 integrase strand transfer inhibitor currently marketed at a dose of 400 mg twice-daily (b.i.d.). Raltegravir 1200 mg once-daily (q.d.) (investigational q.d. formulation of 2 × 600 mg tablets; q.d. RAL) was found to be generally well tolerated and non-inferior to the marketed 400 mg b.i.d. dose at 48 weeks in a phase 3 trial. Since raltegravir is eliminated mainly by metabolism via a uridine diphosphate glucuronosyltransferase (UGT) 1A1-mediated glucuronidation pathway, co-administration of UGT1A1 inhibitors may increase the plasma levels of q.d. RAL. To assess this potential, the drug interaction of 1200 mg raltegravir using atazanavir, a known UGT1A1 inhibitor, was studied. An open-label, randomized, 2-period, fixed-sequence phase 1 study was performed in adult healthy male and female (non-childbearing potential) subjects ≥ 19 and ≤ 55 years of age, with a body mass index (BMI) ≥ 18.5 and ≤ 32.0 kg/m2 . Subjects (n = 14) received a single oral dose of 1200 mg raltegravir in period 1. After a washout period of at least 7 days, the subjects received oral doses of 400 mg atazanavir q.d. for 9 consecutive days, with a single oral dose of 1200 mg raltegravir co-administered on day 7 of period 2. Serial blood samples were collected for 72 h following raltegravir dosing and analysed using a validated bioanalytical method to quantify raltegravir plasma concentrations. Co-administration with atazanavir yielded GMRs (90% CIs) for raltegravir AUC0-∞ , Cmax and C24 of 1.67 (1.34, 2.10), 1.16 (1.01, 1.33) and 1.26 (1.08, 1.46), respectively. There was no effect of raltegravir on serum total bilirubin. In contrast, atazanavir increased the mean bilirubin by up to 200%, an effect that was preserved in the atazanavir/raltegravir treatment group. Administration of single q.d. RAL alone and co-administered with multiple oral doses of atazanavir were generally well tolerated in healthy subjects. The results show that atazanavir increased the PK exposure of raltegravir; therefore, co-administration of atazanavir with raltegravir q.d. is not recommended. Copyright © 2016 John Wiley & Sons, Ltd.

Application of High-Resolution MS for Development of Peptide and Large-Molecule Drug Candidates

For quantitative bioanalysis utilizing MS, the instrument of choice is typically a triple quadruple mass spectrometer. However, advances in high-resolution MS have allowed sensitivity and dynamic ranges to approach that of triple quadrupole instruments. A matrix-free protein digest, a digested therapeutic protein and the intact peptide therapeutic liraglutide were each analyzed on high-resolution and triple quadrupole mass spectrometers with data compared. Samples from a mouse PK study with liraglutide were analyzed using the two different instruments, and equivalent PK exposure data were demonstrated. High-resolution and triple quadrupole mass spectrometers can generate data resulting in identical PK parameters from an in-life sample set, thus giving confidence in either technique in support of biotherapeutic PK exposure studies.

Abstract PR10: RAD1901, an orally available selective estrogen receptor downregulator, has potent anti-tumor activity in in vitro and in vivo models of ER+ breast cancer

Abstract Breast cancer is the most frequent type of cancer diagnosed in women, with over 200,000 new cases diagnosed in the US each year. Treatment strategies are typically based on the tumors receptor status; that is, whether a tumor expresses estrogen receptor (ER), progesterone receptor (PR), or Her2. Estrogen receptor positive (ER+) breast cancers comprise approximately two-thirds of all breast cancers. For decades the approach to treat ER+ disease revolved around altering the ligand interactions with the receptor; either by preventing estrogen binding (e.g., tamoxifen) or preventing estrogen biosynthesis (aromatase inhibitors). While patients typically respond well to these agents, estrogen-independent ER activity and recurrent ER mutations are increasingly being reported as contributing factors to endocrine resistance and continue to be a clinical hurdle. Given this growing unmet medical need, selective estrogen receptor downregulators, or SERDs, have gained widespread attention as new therapeutic treatment strategies for ER + disease. Indeed, fulvestrant has been shown to downregulate ER and cause tumor growth inhibition in many ER+ breast cancer models. However, in the clinic fulvestrant appears to be limited by PK exposure properties and this, combined with its intramuscular route of administration, underscores the need for novel orally available SERDs. Here, we describe RAD1901, an orally administered SERD that binds ER and targets it for degradation in a dose-dependent manner. Biochemical affinity binding studies and cocrystallization experiments revealed insights into RAD1901 complexes with both wild-type and mutant forms of ER. In addition, RAD1901 treatment resulted in decreased cell proliferation in in vitro breast cancer cell lines and had profound single agent tumor growth inhibition in in vivo xenograft models. Consistent with these findings, RAD1901 treatment resulted in decreased expression levels of ER target genes. Interestingly, the extent of tumor growth inhibition induced by RAD1901 in vivo was dependent on ER expression levels, demonstrating the specificity of RAD1901 and predicting its activity in ER-driven cancers. Importantly, RAD1901 was also able to induce significant tumor growth inhibition in clinically relevant and representative patient-derived xenograft models, at a level similar to or greater than fulvestrant. In conclusion, our preclinical data demonstrate that RAD1901 is an orally available SERD, with potent single agent antitumor activity. RAD1901 is currently under clinical investigation in post-menopausal women with advanced ER+ disease. Citation Format: Teeru Bihani, Jeffrey Brown, Gary Hattersley, Fiona Garner. RAD1901, an orally available selective estrogen receptor downregulator, has potent anti-tumor activity in in vitro and in vivo models of ER+ breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR10.

Abstract 5144: Low dose sorafenib delays hepatocellular cancer (HCC) development in the woodchuck model of hepatitis B related HCC

Abstract Introduction: The eastern woodchuck is an established model of human hepatitis B viral infection and spontaneously develops HCC in the context of chronic woodchuck hepatitis viral infection (WHV) at a median age of 24 months. In this translational model of angiogenesis driven HCC, we evaluated the impact of sorafenib on delaying HCC development. Methods: Woodchucks were bred and inoculated at birth with titered infectious WHV pools obtained from chronic WHV carriers. By 12 months of age, the rate of chronic WHV infection was >60%. Animals were trained to receive drug orally mixed in a liquid diet. After an initial single dose woodchuck PK study it was predicted that sorafenib given orally M-F at 2.5 mg/kg once daily or 5mg/kg daily would achieve exposure in woodchucks ∼ 2x IC50 and 5X IC50 for all targets of sorafenib. This is within the exposure achieved in humans where the starting dose achieves exposures that are ∼ 10-12X IC50. We hypothesized that for both long term tolerability and delaying of HCC development, lower doses maybe ideal. Viral titers of WHV DNA were serially assessed, PK exposure of sorafenib and serial ultrasound (USG) was done q2 weeks to assess HCC development. Six WHV+ animals of similar age per arm were randomized to Placebo (P), low or high dose sorafenib. Time to tumor development (TTD) was measured from start of therapy to first occurrence of at least one 2 cm HCC was confirmed on 2 serial USGs. Tumor volume of all tumors seen was assessed as tumor burden. Results: Median TTD was 393 days, 490 and 498 days in the P, low and high dose sorafenib groups respectively. No toxicity was seen and PK results showed exposures as predicted in the two sorafenib groups. The tumor burden adjusted for the duration of therapy was significantly lower in the low dose group than the high dose and P groups. We evaluated three possible mechansims for this delay in HCC. WHV titers decreased as tumor burden increased as viral replication halts when malignant transformation occurs. The delay in TTD was not secondary to an antiviral effect that is known in this model and in humans to delay HCC occurrence. Anti-angiogenic effect was measured on H/E following necropsy as tumor necrosis and involved 7% of the total tumor volume in low dose and 13% of total tumor volume in high dose animals and 0% in P animals. High dose sorafenib inhibited the ex-vivo mixed lymphocyte reaction of woodchuck PBMC whereas low dose sorafenib did not which mechanistically may explain the difference seen in tumor burden with low compared to high dose sorafenib. Conclusions: The delay in HCC by 100 days seen in woodchucks would translate into a 3-9 years delay in HCC occurrence in humans. The tolerability at low dose for over 2 years, lower tumor burden and differential immune effects seen at low dose vs higher dose have great translational significance in the light of the recently completed STORM trial. Support: Sorafenib: Bayer. Funding: ACS- MSRG 08-096-01-CCE Citation Format: Renuka V. Iyer, Sandra Sexton, Leslie Curtin, Gerald Fetterly, Orla Maguire, Hans Minderman, Ilia Toshkov, Bud Tennant, Alan Hutson, Donald L. Trump, Candace Johnson. Low dose sorafenib delays hepatocellular cancer (HCC) development in the woodchuck model of hepatitis B related HCC. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5144. doi:10.1158/1538-7445.AM2015-5144

Mild method for succinimide hydrolysis on ADCs: impact on ADC potency, stability, exposure, and efficacy.

The stability of the connection between the antibody and the toxin can have a profound impact on ADC safety and efficacy. There has been increasing evidence in recent years that maleimide-based ADCs are prone to payload loss via a retro-Michael type reaction. Herein, we report a mild method for the hydrolysis of the succinimide-thioether ring which results in a "ring-opened" linker. ADCs containing this hydrolyzed succinimide linker show equivalent cytotoxicity, improved in vitro stability, improved PK exposure, and improved efficacy as compared to their nonhydrolyzed counterparts. This method offers a simple way to improve the stability, exposure, and efficacy of maleimide-based ADCs.

Abstract CT204: The pharmacokinetics and safety of idelalisib in subjects with severe renal impairment

Abstract Background: Idelalisib (IDELA) is a novel, potent inhibitor of PI3Kδ, which has been shown to be prominently expressed in cells of hematopoietic origin. Renal elimination plays a minor role on elimination of IDELA in humans (∼ 15% of dose excreted in urine). The objective of the present study was to evaluate the PK and safety of IDELA and GS-563117 (primary metabolite) in subjects with severe renal impairment (RI) following a single oral dose of IDELA. Methods: Subjects with severe RI (eGFR 15 - 29 ml/min) and healthy matched controls (eGFR ≥ 80 ml/min) received IDELA 150 mg single dose. Blood and urine samples were collected over 6 days and IDELA/GS-563117 levels were measured using a validated LC/MS/MS method. Geometric least-squares mean ratio and 90% confidence interval of PK exposure parameters in the RI group versus matched controls were calculated, with clinically relevant exposure change defined as ≥ two-fold increase. Safety assessments were performed throughout the study. Results: A total of 12 subjects were enrolled in the study. The majority of subjects were female, white, and of non-Hispanic/Latino ethnicity, and the median age was similar between the 2 groups. Study treatments were generally well tolerated. All AEs were Grade 1 in severity. No clinically significant abnormal changes were observed in vital signs and ECG results from baseline. The AUClast, AUCinf, and Cmax geometric least-squares mean ratio were 127%, 127%, and 105% for IDELA and 124%, 124%, and 96% for GS-563117, respectively, for subjects with severe renal impairment vs matched control subjects (Table 1). There were no relevant relationships between IDELA or GS-563117 exposures and baseline eGFR. Conclusion: There were no clinically relevant differences in the PK of IDELA or GS-563117 between subjects with severe RI vs matched healthy control subjects following a single oral dose of IDELA 150 mg. Dose adjustments for IDELA are not considered necessary in subjects with mild, moderate, or severe renal impairment. PK Parameters in Severe RI and Matched Healthy SubjectsPK ParameterMean (%CV)% Geometric Least Squares Means Ratio(90% CI)Matched Control Group(N = 6)Severe Renal Impairment Group(N = 6)IDELACmax (ng/mL)2530 (27)2680 (28)105 (77, 143)Tmax (h)2.50 (2.00, 3.00)3.00 (2.00, 3.00)t1/2 (h)9.48 (7.37, 10.2)12.1 (6.25, 23.1)AUClast (ng·h/mL)11700 (20)15500 (37)127 (91, 176)AUCinf (ng·h/mL)11800 (20)15700 (37)127 (92, 176)GS-563117Cmax (ng/mL)2590 (21)2570 (37)96 (69, 134)Tmax (h)4.00 (3.00, 4.00)4.00 (4.00, 6.00)t1/2 (h)11.4 (10.9, 12.1)15.8 (8.87, 21.7)AUClast (ng·h/mL)35800 (31)50300 (60)124 (71, 215)AUCinf (ng·h/mL)36000 (30)50800 (61)124 (72, 215) Tmax and T1/2 expressed as median (Q1, Q3) Citation Format: Feng Jin, Michelle Robeson, Huafeng Zhou, Grace Hisoire, Srini Ramanathan. The pharmacokinetics and safety of idelalisib in subjects with severe renal impairment. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT204. doi:10.1158/1538-7445.AM2014-CT204

The Pharmacokinetics and Safety Of Idelalisib In Subjects With Severe Renal Impairment

AbstractAbstract 5572 BackgroundIdelalisib (IDELA) is a potent competitive inhibitor of the ATP binding site of the PI3K p110δ catalytic domain, which has been shown to be prominently expressed in cells of hematopoietic origin. Pharmacokinetics of IDELA and its major metabolite GS-563117 have been assessed in a number of clinical studies in healthy subjects and patients with hematologic malignancies. IDELA is metabolized primarily by aldehyde oxidase to form GS-563117 and to a lesser extent by CYP3A and UGT1A4. Based on a human mass balance study, renal elimination plays a minor role on elimination of IDELA (∼ 15% of dose excreted in urine). The objective of the present study was to evaluate the pharmacokinetics and safety of IDELA and GS-563117 in subjects with severe renal impairment following administration of a single oral dose of IDELA. MethodsSubjects with severe renal impairment (RI) (eGFR 15 – 29 ml/min) and healthy controls (eGFR ≥ 80 ml/min) matched for age, gender, and body mass index received IDELA 150 mg single dose. Blood and urine samples for IDELA and GS-563117 were collected over 6 days post-dose and were measured using a validated LC/MS/MS method. The ratio and 90% confidence interval of the least squares geometric means of PK exposure parameters in the renal impairment group versus matched controls were calculated, with clinically relevant exposure change defined as ≥ two-fold increase. Safety assessments were performed throughout the study. ResultsA total of 12 subjects were enrolled in the study. The majority of subjects were female, white, and of nonHispanic/Latino ethnicity, and the median age was similar between the 2 groups (65 years of age for the severe group and 63 years for the healthy control group). Study treatments were generally well tolerated. Overall, 6 of 12 subjects (50.0%; 1 subject with severe renal impairment and 5 healthy matched control subjects) reported a total of 10 AEs; all were Grade 1 (mild) in severity. The most frequently reported AE was headache followed by nausea. No clinically significant abnormal changes were observed in vital signs (temperature, pulse, blood pressure, respiratory rate) and ECG results from baseline. Single oral doses of IDELA 150 mg were well tolerated.Following single oral administration of IDELA 150 mg, IDELA AUClast, AUCinf, and Cmax geometric least-squares mean ratio were 127%, 127%, and 105%, respectively, between subjects with severe renal impairment relative to matched control subjects (Table 1). Consistently, GS-563117 AUClast, AUCinf, and Cmax geometric least-squares mean ratio were 124%, 124%, and 96%, respectively, between subjects with severe renal impairment relative to matched control subjects. These minimal changes observed in IDELA and GS-563117 exposure in severe renal impairment vs matched control subjects are not considered to be clinically meaningful. There were no relevant relationships between IDELA or GS-563117 exposures and baseline estimated creatinine clearance. ConclusionThere were no clinically relevant differences in the pharmacokinetics of IDELA or its primary metabolite GS563117 between subjects with severe renal impairment and matched healthy control subjects following a single oral dose of IDELA 150 mg. Dose adjustments for IDELA are not considered necessary in subjects with mild, moderate, or severe renal impairment following oral administration. Single oral doses of IDELA 150 mg were well tolerated. Disclosures:Jin:Gilead Sciences: Employment, Equity Ownership. Robeson:Gilead Sciences: Employment, Equity Ownership. Zhou:Gilead Sciences: Employment, Equity Ownership. Hisoire:Gilead Sciences: Employment, Equity Ownership. Ramanathan:Gilead Sciences: Employment, Equity Ownership.

The Pharmacokinetics and Safety Of Idelalisib In Subjects With Moderate Or Severe Hepatic Impairment

BackgroundIdelalisib (IDELA) is a potent competitive inhibitor of the ATP binding site of the PI3K p110s catalytic domain, which has been shown to be prominently expressed in cells of hematopoietic origin. IDELA is metabolized primarily by aldehyde oxidase to form GS-563117 and to a lesser extent by CYP3A and UGT1A4. Based on mass balance study of IDELA, the majority of the radioactive dose administered in healthy subjects was recovered in feces (∼78%). The objective of the present study was to evaluate the pharmacokinetics and safety of IDELA and GS-563117 in subjects with moderate or severe hepatic impairment following administration of a single oral dose of IDELA. MethodsEligible subjects were enrolled into 2 cohorts that included subjects with moderate or severe hepatic dysfunction as categorized by the ChildPugh-Turcotte (CPT) classification system and healthy controls matched for age, gender, and body mass index. Each subject received a single oral dose of IDELA at 150 mg under fed condition. Blood samples for IDELA and GS-563117 were collected over 6 days post-dose and were measured using a validated LC/MS/MS method. The ratio and 90% confidence interval of the least squares geometric means of PK exposure parameters in the hepatic impairment group(s) versus matched controls were calculated, with clinically relevant exposure change defined as ≥ two-fold increase. Safety assessments were performed throughout the study. ResultsA total of 32 subjects were enrolled in the study. The majority of subjects were white (87.5%) males (71.9%) and median age was 52 years. Study treatments were generally well tolerated. The majority of the treatment-emergent AEs (TEAE) were assessed as Grade 1 in severity. The only TEAE reported in more than 1 subject was headache (5 subjects overall; 2 subjects with moderate hepatic impairment and 3 healthy subjects). Most treatmentemergent laboratory abnormalities were Grade 1 or 2 in severity. Single oral doses of IDELA 150 mg were well tolerated in subjects with hepatic impairment and in healthy matched controls.IDELA Cmax was generally comparable in the subjects with moderate (CPT Class B) or severe (CPT Class C) hepatic impairment relative to healthy matched control subjects, while mean AUC was higher (58% to 60%). GS-563117 exposures were lower in subjects with moderate and severe hepatic impairment relative to matched healthy control subjects, likely due to lower formation in the setting of liver impairment. Overall, the observed changes in mean exposures of IDELA and GS-563117 are not considered to be clinically relevant. Exploratory analyses indicated no relevant relationships between the IDELA or GS-563117 plasma exposures and CPT score for subjects with moderate or severe hepatic impairment. ConclusionNo clinically relevant changes in IDELA and GS-563117 exposures were observed in subjects with moderate or severe hepatic impairment versus matched healthy control subjects. Single oral doses of IDELA 150 mg were well tolerated.Table 1Pharmacokinetics Parameters of IDELA and GS-563117 following a Single Oral Dose of IDELA at 150 mg in Moderate or Severe Hepatic Impaired and Matched Healthy SubjectsPK ParameterMean (%CV)% Geometric Least Squares Means Ratio (90% CI)Matched Control Group (N = 10)Moderate Hepatic Impairment Group (N = 10)IDELACmax (ng/mL)2170 (26)2010 (20)94 (77, 113)AUClast(ng·h/mL)10400 (29)16600 (29)159 (126, 201)AUCinf(ng·h/mL)10500 (28)16700 (29)158 (125, 199)GS-563117Cmax (ng/mL)2040 (20)1830 (35)86 (68, 110)AUClast(ng·h/mL)10200 (32)16400 (35)160 (121, 210)AUCinf(ng·h/mL)10300 (31)16500 (35)159 (121, 208)PK ParameterMean (%CV)% Geometric Least Squares Means Ratio (90% CI)Matched Control Group (N = 10)Severe Hepatic Impairment Group (N = 9)IDELACmax (ng/mL)1940 (35)1130 (54)54 (38, 77)AUClast(ng·h/mL)25000 (58)23400 (64)89 (58, 137)AUCinf(ng·h/mL)25200 (58)23600 (63)89 (58, 136)GS-563117Cmax (ng/mL)1870 (33)703 (66)29 (17, 51)AUClast(ng·h/mL)23900 (64)15600 (67)53 (28, 101)AUCinf(ng·h/mL)24200 (64)15700 (66)54 (29, 100) Disclosures:Jin:Gilead Sciences: Employment, Equity Ownership. Robeson:Gilead Sciences: Employment, Equity Ownership. Zhou:Gilead Sciences: Employment, Equity Ownership. Hisoire:Gilead Sciences: Employment, Equity Ownership. Ramanathan:Gilead Sciences: Employment, Equity Ownership.

AB0268 Lack of correlation between golimumab exposure and selected safety events following intravenous or subcutaneous administration in an integrated analysis of phase 3 data in rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis

BackgroundFor anti-TNFα agents, infections&malignancies are key safety concerns of interest. It is unknown whether safety events are driven by peak (Cmax), trough (Cmin), average (Cavg) conc or by total systemic...

Physicochemical, functional, and pharmacologic comparability between the proposed biosimilar rituximab GP2013 and originator rituximab as the foundation for biosimilarity.

3075 Background: Development of a biosimilar involves extensive characterization of the originator product and a target-directed iterative development process ensuring comparability to the originator with similar clinical efficacy, safety and quality. Here we report the physicochemical, functional and pre-clinical pharmacological characterization of a proposed rituximab biosimilar (GP2013). Methods: A variety of physicochemical methods were used to analyze primary and higher order structure, post-translational modifications and size heterogeneity. Functional characterization included a series of bioassays (in vitro target binding, ADCC, CDC and apoptosis) and SPR-based Fc receptor binding assays. Comparative PK and PD were assessed in cynomolgus monkeys, the pharmacologically most relevant species. Results: GP2013 has the same primary amino acid sequence and higher order structure as the originator rituximab and both were comparable with regard to charge variants, specific amino acid modifications, glycan pattern and size heterogeneity (low- and high-molecular weight variants & particles). Functionally GP2013 could not be distinguished from originator rituximab preclinically. In primates, PK analysis confirmed bioequivalence between GP2013 and originator rituximab with nearly identical AUC values and 90% CIs entirely within the standard acceptance range of 0.8-1.25. Bioequivalence of PD response was also shown, with 95% CIs of areas under the effect-time curves (AUEC) ratios for relative change from baseline in B-cell populations within the 0.8-1.25 acceptance range. Conclusions: Using a broad panel of analytical methods it was shown that GP2013 is highly similar to originator rituximab at the physicochemical level. In addition, the preclinical comparability exercise confirmed that GP2013 and originator rituximab are pharmacologically similar with regard to FcR and CD20 binding, ADCC, CDC and apoptosis potency, PK exposure and B-cell depletion. As such, we anticipate that the ongoing clinical trials will help provide confirmatory evidence of similar efficacy and safety to the originator product.

Abstract LB-201: Clinical pharmacology characterization of RG7112, an MDM2 antagonist, in patients with advanced solid tumors.

Abstract MDM2 is overproduced as a mechanism to impair p53 function in many cancers. By reactivating p53, antagonists of p53-MDM2 interaction could offer a novel approach to treatment of solid tumors and leukemias. RG7112, the first potent and selective small-molecule MDM2 antagonist in clinical testing, is an oral p53 activator and is currently in phase I. To optimize its dose and schedule, a number of clinical pharmacology characteristics were explored in this multi-center trial in patients (pts) with advanced solid tumors. In Part I, the impact of high-energy/high-fat meal and formulation (crystalline versus amorphous) was examined in cross-over design. In Part II, schedule optimization (4 schedules of drug adm under fasting condition and 1 cohort with liquid supplementation) was investigated in parallel, dose escalation design. Clinical endpoints were PK/PD and safety/tolerability including platelet reduction (a potential target-mediated hematological toxicity indicator). A total of 76 pts (42F and 34M, mean age 60 yr) participated in the study. In their first-cycle treatment, 36 pts received weekly x3 (26 with food/formulation evaluation), 15 pts daily x5, 6 pts daily x20, and 19 pts daily x3 (3 with food evaluation) doses; daily doses ranged from 500-4500 mg. The most commonly reported AEs (> 20%) were GI-related. Twelve pts have reported 21 SAEs, of which, 4 events in 2 pts (1 pt with G4 thrombocytopenia, anemia, and neutropenia; 1 pt with G3 delirium) were related to study treatment. A high-energy (∼1000 kcal)/high-fat (∼60 g) meal and a reduced energy (∼500 kcal)/fat (∼30 g) liquid supplementation both enhanced overall bioavailability (BA) of tested formulations by 2-fold, with inter-pt variability reduced by half. At steady-state, amorphous formulation also reduced PK variability by half from the crystalline formulation. High-dose consecutive daily dosing for 5 and 3 d yielded highest drug concentrations on the last day of treatment. On the other hand, both weekly and low-dose/long-duration (20-day) schedules yielded lower peak concentrations (note that the per-cycle exposure was comparable to, or higher than, high-dose 5x and 3x daily schedules). Serum profiles of MIC-1, a secreted protein that is strongly induced by activated p53, showed similar patterns to the PK when the clinical pharmacology conditions were varied. The first-cycle platelet profiles indicate that the weekly schedule didn't cause platelet reduction, while the daily schedules showed a trend of dose- and length-dependent platelet reduction with daily x 5 at high doses being the most pronounced (1 pt resulted in G-4 thrombocytopenia). In conclusion, RG7112 is well tolerated with or without food in the therapeutically relevant dose range, food enhanced BA with reduced variability, and high-dose consecutive daily for 3-5 d is superior in yielding sufficiently high PK exposure and PD effects potentially required for cancer treatment efficacy. Citation Format: Amita Patnaik, Anthony Tolcher, Muralidhar Beeram, John Nemunaitis, Glen Weiss, Gwen Nichols, Steven Middleton, Nenad Sarapa, Anna Beryozkina, Jianguo Zhi. Clinical pharmacology characterization of RG7112, an MDM2 antagonist, in patients with advanced solid tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-201. doi:10.1158/1538-7445.AM2013-LB-201

Phase Ib trial of AVL-292, a covalent inhibitor of Bruton's tyrosine kinase (Btk), in chronic lymphocytic leukemia (CLL) and B-non-Hodgkin lymphoma (B-NHL).

8032 Background: Btk supports activation, survival, and proliferation of malignant B cells in CLL and B-NHL. AVL-292 is an oral, potent (IC50 < 0.5nM), selective small molecule covalent inhibitor of Btk. Methods: Patients (pts) with previously treated CLL or B-NHL were administered AVL-292 in escalating cohorts of 125, 250, or 400 mg po QD using a 3+3 design in continuous 28 day cycles until progressive disease (PD) or toxicity. Key objectives were safety, DLT, MTD, PK, and Btk occupancy. Plasma AVL-292 levels were assessed by LC-MS-MS. Btk occupancy by AVL-292 was assessed by covalent probe assay in peripheral blood mononuclear cells. Results: 12 pts have enrolled (3 each at 125 and 250 mg and 6 at 400 mg: 5M/7F; median age 68 years, range 45-79; median 2.5 prior therapies, range 1-10) including 8 CLL (2 with 17p-, 2 with 11q22-, 2 with both 17p-/11q22-; 2 mutated IGHV, 5 unmutated IGHV, 1 missing) and 4 B-NHL (1 diffuse large B cell lymphoma (DLBCL); 1 follicular (FL); 2 marginal zone (MZL)). Median time on treatment is 65 days, range 28-158. Ten of 12 pts continue on treatment: 1 pt (DLBCL) discontinued for PD after 1 cycle and 1 pt (FL) for DLT (Gr 4 plts; 400 mg QD). No other DLTs or grade 4 adverse events (AEs) have occurred and MTD has not been reached. Most frequent AEs reported include transient diarrhea, rash/skin infection, URI, nausea, and fatigue. Gr 3 AEs include 1 atrial fibrillation (not drug related) and 1 ANC low (probably drug related). To date, 8 of 8 CLL patients have stable disease (SD) with median 28% decrease from baseline lymph node measurement (range 3-40% decrease). Six of 8 pts with CLL experienced increased ALC in cycle 1: median increase 89.5% (range 50-212%). Two of 4 NHL pts have SD (both MZL), 1 PD (DLBCL), and 1 not evaluable due to DLT (FL). Full Btk occupancy was achieved with dose levels ≥ 250 mg. Multiple dose PK exposure (AUClast) was linear with no accumulation from Day 1 to 15. Conclusions: AVL-292 was well tolerated from 125-400 mg po QD and early efficacy analysis in CLL and B-NHL shows 10/11 efficacy evaluable pts with SD. Full Btk occupancy was achieved with ≥ 250 mg QD and PK was predictable with no accumulation. Dose escalation is ongoing and MTD cohort expansion is planned.

Abstract C206: In vivo activity of SGI-1252, a potent, small-molecule dual inhibitor of JAK2 and ALK2

Abstract Activation of JAK2, an intracellular protein tyrosine kinase, is known to induce cell proliferation and apoptosis and it has been shown to be mediated by pro-inflammatory cytokines. JAK2 dysregulation is implicated in myeloproliferative disorders, solid tumor malignancies, and autoimmune diseases. Utilizing our proprietary CLIMB™ technology, a computationally driven drug discovery process, we have rapidly designed and developed, SGI-1252, a potent oral inhibitor which exhibits low nanomolar in vitro activity against all of the JAK kinase family, except JAK3. Additionally, it has low nanomolar activity against ALK2, a high-affinity binding receptor for bone morphogenic protein. As predicted from computational models, SGI-1252 is well tolerated across several rodent species and demonstrates a wide safety margin in both short- and long-term toxicity studies. Acute maximum tolerated doses of greater than 900 mg/kg are observed in mice and rats dosed orally with SGI-1252. Over a 5-week period, daily oral dosing of up to 200 mg/kg SGI-1252 shows no hematological toxicity and no body weight loss in mice. Pharmacokinetic studies of SGI-1252 in rodents also demonstrate excellent systemic exposure, with oral bioavailabilities of greater than 50% in mice and rats. Because inflammatory cytokines are known to play a role in the pathogenesis of pancreatic and lung cancers, tumor xenograft models of those cell lines were evaluated. In BxPC3 and A549 xenografts, three weeks of daily oral dosing of 200 mg/kg SGI-1252 demonstrate exceptional activity, with tumor inhibitions of greater than 50% in both models. Pharmacodynamic studies were also performed to further elucidate the effect of SGI-1252 on pro-inflammatory cytokines related to these models. In several acute-phase mouse models, where turpentine-oil injection are utilized for cytokine stimulation, SGI-1252 is observed to down-regulate IL-6 and VEGF expression 16–24 hours after dosing. In summary, SGI-1252 is a potent oral inhibitor that is well tolerated in rodent models, provides excellent PK exposure, and demonstrates tumor growth inhibition as well as modulation of pro-inflammatory cytokines. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C206.

Abstract A190: In vivo activity of SGI-110, a novel hypomethylating agent for treatment in hematology and solid malignancies

Abstract SGI-110 is a second generation hypomethylating agent being developed for treatment in myelodysplastic syndrome (MDS) and solid tumor malignancies. In previous work, SGI-110 has demonstrated potent in vivo activity in a number of tumor types, including non-hematological cell lines. Current efforts are underway to optimize formulation and delivery of SGI-110 for first-in-human (FIH) studies. In animals, SGI-110 is well-tolerated across multiple species utilizing multiple routes of drug delivery. Tolerability studies have been performed in mouse, rat, and rabbit models with multiple dose routes and schedules. Myelosuppression is an observed toxicity endpoint for hypomethylating agents. Hence, myelotoxic effects were investigated by comparing RBCs and bone marrow cellularity of mice treated with and without SGI-110. Mice dosed with SGI-110 for five consecutive days showed a significant decrease in RBCs at the end of the dosing period and a continued decrease one week after dosing. Bone marrow cellularity also showed a decrease at the end of dosing, but recovered to near normal levels one week later. Interestingly, RBCs from SGI-110 treated mice were elevated in the bone marrow after the dosing period. Pyrosequencing methylation analysis of colon samples was also evaluated in this study. A significant decrease in B1 methylation was observed in colon samples of treated mice, indicating global DNA methylation is being inhibited. Decreased levels in several hematology parameters and decreases in bone marrow cellularity were also observed in rat and rabbit studies after five consecutive days of SGI-110 dosing. Increased dosing frequency, while maintaining the same total dose per week, appears to result in increased toxicity. Previous pharmacokinetic studies have shown that SGI-110 rapidly metabolizes to decitabine, an FDA-approved drug for MDS. Multiple formulations and different routes of delivery were examined to determine the optimal dose form to be used in FIH studies. Subcutaneous dosing results in bioavailability that is similar to that of intravenous dosing. Subcutaneous dosing appears to reduce the Cmax while maintaining similar AUC values when compared to intravenous dosing. Similar results in pharmacokinetic parameters are observed when the delivery vehicle is changed from an aqueous to non-aqueous formulation. SGI-110 is a novel hypomethylating agent that is well-tolerated in rodent models, provides excellent PK exposure, and demonstrates inhibition of DNA methylation in a mouse model. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A190.

An Ongoing Phase 1/2a Study of ABT-263; Pharmacokinetics (PK), Safety and Anti-Tumor Activity in Patients (pts) with Relapsed or Refractory Chronic Lymphocytic Leukemia (CLL).

Abstract 883ABT-263, a novel orally bioavailable BH3 mimetic, binds with high affinity (Ki ≤ 1nM) and inhibits multiple antiapoptotic Bcl-2 family proteins. In vitro, ABT-263 potently induces apoptosis (EC50 ≤ 1μM) in Bcl-2 overexpressing human lymphoma cell lines and primary CLL cells. Preclinical mechanism-based toxicities include inhibition of spermatogenesis, reduction in circulating lymphocytes and decreased survival of circulating platelets, reflecting inhibition of Bcl-w, Bcl-2 and Bcl-XL, respectively. Study M06-873 is a phase 1/2a dose-escalation trial employing a continuous reassessment method (CRM) to evaluate ABT-263 PK, safety and antitumor activity of two dosing schedules in pts with relapsed or refractory CLL. Tumor responses were evaluated by the NCI-WG criteria. Pts were initially dosed on d1-14 of a 21d cycle with 10-250 mg ABT-263. To ameliorate the impact of thrombocytopenia (TCP) due to on-target Bcl-XL inhibition-induced platelet apoptosis, a 100 mg lead-in dose for 7d followed by continuous 21/21d dosing (up to 300mg/d) was investigated. This study has completed enrollment at 300 mg with 29 pts (15 on a 14/21d; 14 on a 21/21d schedule) as of June 2009. The PK exposure of ABT-263 was approximately dose-proportional from 10-300 mg with a terminal half-life of 11 h. Platelet nadirs were transient, occurring on d3-5 followed by partial recovery due to compensatory increased megakaryopoiesis during continued dosing. Lead-in dosing reduced the early platelet nadir, and minimized fluctuations in platelet count observed with intermittent dosing. Circulating platelet count dropped maximally during cycle 1 by an average 12%, 57%, 68% and 70% from baseline at 10 mg, 110 mg, 200 and 250 mg for the 14/21d schedule, and an average of 52%, 63%, 63% and 68% from baseline at 125 mg, 200 mg, 250 mg and 300 mg for the 21/21d schedule. Of the 21 evaluable pts, 2 had radiographically confirmed partial responses (99% and 79% reductions) and 3 had as yet unconfirmed nodal regression (100%, 71% and 55%). 7 pts maintained a ≥50% decrease in circulating absolute lymphocyte count for ≥ 2 months with 2 pts having PR by physical examination; the overall response rate was 33%. Stable disease was noted in 8 pts and 2 pts had progressive disease. Responses tend to be durable, with the median PFS not yet reached while the median time on study is 9 mos (range 0.63 - 18.4 mos). The most common adverse events (AE) were diarrhea (52%), nausea (44%), vomiting (24%), fatigue (24%) thrombocytopenia (TCP; 20%) and neutropenia (12%). Dose limiting toxicities (DLT) were observed in 3 pts on the 14/21d schedule; 2 at 110mg (hospitalization & Grade 4 TCP) and 1 at 250 mg (Grade 4 TCP). Among the 14 pts on the 21/21d schedule, 3 pts experienced DLT; 1 at 200 mg (Grade 4 TCP); 1 at 250 mg (Grade 2 nausea) and 1 at 300 mg (Grade 4 TCP). ABT-263 was well-tolerated and had favorable PK and acceptable safety profiles. One week 100mg/d lead-in followed by continuous dosing minimizes platelet nadir and cycle variability. Based on the 21/21d continuous dosing data, the CRM model projection for MTD converged. The recommended phase 2 dose is 100 mg 7-d lead-in followed by 250 mg/d continuous dosing. Disclosures:Roberts:Abbott : Research Funding; Genentech: Research Funding. Off Label Use: ABT-263 is an experimental drug that is not yet registered. It is designed to induce apoptosis in tumor cells.. Brown:Celgene: Research Funding; Genzyme: Research Funding. Wierda:GSK: Consultancy; Ligand: Consultancy; Genentech: Consultancy; MEDIMMUNE: Consultancy; ABBOTT: Consultancy; TRUBION: Consultancy; BAYER, SANOFI-AVENTIS, MEMGEN, GENITOPE, GENMAB, SUNESIS, ABBOTT, GSK: Research Funding; GENENTECH: Honoraria; CELGENE: Speakers Bureau. Xiong:Abbott: Employment. Cui:Abbott: Employment. Busman:Abbott: Employment. Enschede:Abbott: Employment. Krivoshik:Abbott: Employment. Humerickhouse:Abbott: Employment.

4-Aminophenylalanine and 4-aminocyclohexylalanine derivatives as potent, selective, and orally bioavailable inhibitors of dipeptidyl peptidase IV

A novel series of 4-aminophenylalanine and 4-aminocyclohexylalanine derivatives were designed and evaluated as inhibitors of dipeptidyl peptidase IV (DPP-4). The phenylalanine series afforded compounds such as 10 that were potent and selective (DPP-4, IC 50 = 28 nM), but exhibited limited oral bioavailability. The corresponding cyclohexylalanine derivatives such as 25 afforded improved PK exposure and efficacy in a murine OGTT experiment. The X-ray crystal structure of 25 bound to the DPP-4 active site is presented.

Population Pharmacokinetics and Bayesian Estimator of Cyclosporine in Pediatric Renal Transplant Patients

Cyclosporine A (CsA) is an immunosuppressive drug widely used in pediatric renal graft recipients. Its large interindividual pharmacokinetic variability and narrow therapeutic index render therapeutic drug monitoring necessary. However, information about CsA pharmacokinetics is scarce and no population pharmacokinetic (popPK) studies in these populations have been reported so far. to the objectives of this study were 1) to develop a PKpop model and identify the individual factors influencing the variability of CsA pharmacokinetics in pediatric kidney recipients; and 2) to build a Bayesian estimator allowing the estimation of the main PK parameters and exposure indices to CsA on the basis of a limited sampling strategy (LSS). The popPK analysis was performed using the NONMEM program. A total of 256 PK profiles of CsA collected in 98 pediatric renal transplant patients (mean age 9.7 +/- 4.5 years old) within the first year posttransplantation were studied. A 2-compartment model with first-order elimination, and Erlang distribution to describe the absorption phase, fitted the data adequately. For Bayesian estimation, the best LSS was determined based on its performance in estimating area under the concentration-time curve (AUC0-12h) and validated in an independent group of 20 patients. The popPK analysis identified body weight and posttransplant delay as individual factors influencing the apparent central volume of distribution and the apparent clearance, respectively. Bayesian estimation allowed accurate prediction of AUC0-12h using predose, C1h, and C3h blood samples with a mean bias between observed and estimated AUC of 0.5% +/- 11% and good precision (root mean square error = 10.9%). This article reports the first popPK study of CsA in pediatric renal transplant patients. It confirms the reliability and feasibility of CsA AUC estimation in this population. The body weight and the posttransplantation delay were identified to influence PK interindividual variability of CsA and were included in the Bayesian estimator developed, which could be helpful in further clinical trials.

PK and PD of recombinant human IL-18 (rhIL-18) administered IV in repeated cycles to patients with solid tumors

2535 Background: rhIL-18, a potent immunomodulatory cytokine, has demonstrated anti-tumor activity in a variety of preclinical models. Clinical safety and biological activity were examined in a previous study of rhIL-18 administered in a single cycle at IV doses ranging from 3 - 1000 mcg/kg/day for 5 days. The current study examined the effects of administering repeated cycles, and the resulting PK exposure and PD biomarker response data, which are described below. Methods: Three cohorts of 3 patients each were enrolled (6 with melanoma and 3 with metastatic renal cell carcinoma), and received 100, 500, or 1000 mcg/kg doses of rhIL-18 (SB485232) administered as 2h infusions daily for 5 consecutive days every 28 days in repeated cycles (up to 6). Assessments included tolerability, immunogenicity, anti-tumor activity, PK, and biomarkers of immunomodulatory activity. PK and PD measurements were made on Days 1 and 5 of Cycles 1 and 2. Plasma drug concentrations were measured by ELISA. Cytokine/protein biomarkers were measured by ELISA and custom cytokine multiplex biochips. Cell activation biomarkers were measured by flow cytometry. Results: Plasma concentrations of rhIL-18 increased with increasing dose, were comparable between cycles, and exhibited 3-fold accumulation over 5 days with a half-life of 39h. Induction of IFN-gamma, GM-CSF, TNF-alpha, IP-10, MIG, MCP-1, and IL-18 Binding Protein (BP) was observed. These responses were attenuated in the second cycle. Cytokine and chemokine responses were also attenuated within each cycle (Day 5 vs Day 1). Lymphopenia and expression of CD69 on CD4, CD8, and NK cells were maximal 6h after the first infusion at all doses in each cycle, with no apparent attenuation of response. Conclusions: These data suggest that rhIL-18 induces inflammatory cytokine production and cell-mediated immunological activation. The apparent attenuation of cytokine responses with repeated exposure may be due in part to the regulatory effect of BP. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration GlaxoSmithKline

Pharmacokinetic/Pharmacodynamic Model Analysis of Pegylated Interferon .ALPHA.-2a in Healthy Subjects

Data analysis of biological proteins presents a challenge because errant points may indeed reflect the true pharmacokinetic profile of the agent under study. Thus, the most suitable PK/PD model must be used appropriately to avoid reaching a local minimum of fitting results. Pegylated interferon α-2a (PEG-IFN) is interferon α-2a in which one branched polyethylene glycol molecule is conjugated. The half-life of interferon increases upon pegylation and the absorption is sustained, thereby providing greater exposure and the expectation of greater efficacy with just weekly administrations. Four different absorption models were compared in the present study to establish a PK/PD model for PEG-IFN and provide an optimal dosage guideline, where 2', 5'-oligoadenylate synthetase (2', 5'-OAS) is used as the PD marker. An indirect response model (stimulation-kin0) was used to describe PD of PEG-IFN, i.e. 2', 5'-OAS activity.A first-order absorption model was concluded to be the best absorption model to describe PK/PD of PEG-IFN and 2', 5'-OAS activity. The PK of PEG-IFN can be described by a linear process. The mean EC50 at a dose of 180 μg was one-third of its Cmax (ca. 10 ng/mL) which may indicate that 180 μg is the clinically optimal dose because the serum level of PEG-IFN at a dose of 180 μg sustained above EC50 for long time in comparison with the case at a dose of 90 μg and 2', 5'-OAS activity reached a plateau level at a dose of 180 μg, although 2', 5'-OAS activity has not been validated as a surrogate marker of clinical activity.The current PK/PD model well describes the enhanced PD effect, i.e. 2', 5'-OAS induction, as a consequence of the enhanced PK exposure of PEG-IFN. These results confirm the value of applying the PK/PD modeling approach to support the clinical development of potential products.