A Pharmacokinetic and Safety Study of Trebananib, an Fc-Fusion Peptibody, in Patients With Advanced Solid Tumors and Varying Degrees of Renal Dysfunction

Clearance of trebananib (AMG 386), a 64-kD antiangiogenic peptibody, has been associated with estimated glomerular filtration rate (eGFR). We prospectively evaluated trebananib pharmacokinetics and safety/tolerability in advanced solid tumor patients with varying degrees of renal function. Patients were assigned to normal renal function, mild, moderate, or severe renal dysfunction cohorts based on eGFR, received trebananib 15 mg/kg i.v. weekly, and underwent week 1 and week 5 pharmacokinetic and weekly safety assessments. For 28 patients, trebananib clearance decreased from normal renal function (1.52 mL/hr/kg), to mild (1.20 mL/hr/kg), moderate (0.79 mL/hr/kg), and severe (0.53 mL/hr/kg) renal dysfunction (P ≤ 0.001). Treatment-related adverse events showed no association with clearance. Trebananib clearance was proportional to eGFR and unrelated to pretreatment protein excretion. These data confirm a role for renal clearance of a recombinant peptibody with molecular weight <69 kD and support a longer dosing interval for patients with severe renal dysfunction.

Red blood cell damage during experimental prolonged perfusion with membrane oxygenation using fresh human blood

The effects of prolonged perfusion of oxygenated blood have previously been studied with respect to haemolysis and cell morphology. The aim of this study was to examine the effect of mechanical trauma on the microrheology of red blood cells during experimental prolonged perfusion with membrane oxygenation (PPMO). Red blood cell damage was assessed by blood rheological parameters using a St George's filtrometer. Red blood cell filtration rate (RFR, μl/s), clogging rate (RBC-CR, 102%/ml), clogging particle (RBC-CP, 106/ml), mean corpuscular volume (MCV) and haematocrit (Hct) were analysed at the start of PPMO and after 24, 48 and 72 hours. RFR values were 81.3 ± 3.7 at the start, 79.2 ± 7.6 (24 h, p < 0.01), 42.3 ± 8.4 (48 h, p < 0.001) and 25.1 ± 7.0 (72 h, p < 0.001). The mean RBC-CR was 2.45 ± 0.53 at the start; this increased to 3.58 ± 0.9, 6.62 ± 0.92 and then reduced to 4.77 ± 1.39 at 24 (p < 0.0001), 48 (p < 0.0001) and 72 (p < 0.02) hours respectively. Mean RBC-CP at the start was 3.29 ± 0.55; this increased to 3.42 ± 0.72, 5.29 ± 0.68 and 6.09 ± 1.07 at 24, 48 and 72 hours respectively (NS at 24 h and 48 h, p < 0.04 at 72 h). The mean MCV (fl) at the start was 86 ± 4; this increased to 101 ± 2, 111 ± 4 and 119 ± 4 at 24, 48 and 72 hours respectively (p < 0.001). Mean Hct (%) at the start was 33 ± 2; this increased to 38 ± 2, 38 ± 2 and 48 ± 2 at 24, 48 and 72 hours respectively (p < 0.05 at 24 and 48 hours, p < 0.001 at 72 hours). The mean pH and CO 2 (kPa.s) levels were 7.38 ± 0.04 and 4.1 ± 0.7 respectively. This study suggested that there was a continuous loss of red cell rheology during PPMO, which could lead to disturbed microcirculation, thereby increasing the risk of organ ischaemia, hypoxia, dysfunction and failure.

Blood cell rheologic deterioration by complement activation during experimental prolonged perfusion with membrane oxygenation

In order to understand the microcirculatory disturbances during clinical ECMO, the relation of complement activation to blood cell rheologic parameters during prolonged perfusion with membrane oxygenation was studied in 10 experiments using fresh human donor blood. The perfusion set-up was a standard ECMO circuit without a patient. Blood rheologic parameters reflecting the fluidity of blood in the microcirculation were analysed by a St George's Filtrometer. Changes in complement fractions C3a and C5a were measured by the radio-immunoassay (RIA) technique and the TCC (terminal complement complex) by ELISA technique. Samples for complement activation and blood rheological analysis were taken at 24 hours for correlation. There were strong and significant correlations between red and white cell rheologic parameters with all complement fractions. These observations indicate that complement activation plays a significant role in the deterioration of blood rheology during extracorporeal circulation. Improvements in biocompatibility and blood protection are required if this technology is to be made safer.

Phase 1 study of conatumumab, a pro-apoptotic death receptor 5 agonist antibody, in Japanese patients with advanced solid tumors

PURPOSE

Conatumumab is a fully human monoclonal agonist antibody against human death receptor 5 (DR5). The primary objectives of this phase 1 study were to assess the safety, tolerability, and pharmacokinetics (PK) of conatumumab in Japanese patients with advanced solid tumors.

METHODS

This is an open-label ascending dose study with a starting dose level of 3 mg/kg. Subsequent doses of 10 and 20 mg/kg were planned. Six patients were enrolled into 1 of 3 dose cohorts (3, 10, or 20 mg/kg) of conatumumab administered intravenously once every 2 weeks as a single agent. No conatumumab was administered on day 43 to allow the assessment of terminal PK parameters. The primary endpoints were the incidence of dose-limiting toxicities (DLTs) and assessment of PK parameters of conatumumab.

RESULTS

Eighteen patients received at least 1 dose of conatumumab. There were no DLTs observed as defined in the protocol. No patients had an adverse event leading to conatumumab discontinuation. Conatumumab demonstrated dose-linear kinetics. A best response of stable disease was reported in nine patients. Monocytes were found to express DR5 and showed a high degree of conatumumab receptor occupancy after treatment at all dose levels.

CONCLUSIONS

Conatumumab administered up to 20 mg/kg once every 2 weeks was well tolerated in Japanese patients with advanced solid tumors. Adverse events and PK in these patients were similar to those in the first in human (FIH) study.

Abstract C6: Phase 1 study of conatumumab (AMG 655), a proapoptotic death receptor-5 agonist antibody, in Japanese patients with advanced solid tumors

Background: Conatumumab is an investigational, fully human monoclonal agonist antibody that binds human death receptor-5 (DR5, TR-2), activates caspases, and induces apoptosis in sensitive tumor cells. The primary objectives of this phase 1 study were to assess the safety, tolerability, and pharmacokinetics (PK) of conatumumab in Japanese patients (pts) with advanced solid tumors.

Method: This is an open-label ascending dose study with a starting dose level of 3 mg/kg. Subsequent doses of 10 mg/kg and 20 mg/kg were planned. Six pts were enrolled into 1 of 3 dose cohorts (3, 10, or 20 mg/kg) of conatumumab administered intravenously once every 2 weeks as a single-agent. No conatumumab was administered on day 43 to allow assessment of terminal PK parameters. Conatumumab receptor occupancy on monocytes was assessed during the first treatment cycle. Pts remained on study until tumor progression or unacceptable toxicities occurred.

Results: Eighteen pts (6 in each dose cohorts) received at least 1 dose of conatumumab; 9 pts were men; median age was 58 years. Tumor types included: colorectal (5), non-small cell lung (4), gastric (2), soft tissue sarcoma (2) and one each of pancreatic cancer, thymoma, mesothelioma, rectal carcinoid and parotid cancer. The grade 3 adverse events included blood creatine phosphokinase increase, pain and increased lipase. One treatment emergent serious adverse event of pain was reported in cohort 2. This serious adverse event was not considered by the investigator to be related to conatumumab. There were no DLTs observed as defined in the protocol. No deaths occurred during treatment or the safety follow-up period. No subjects had an adverse event leading to conatumumab discontinuation. Conatumumab demonstrated dose-linear kinetics with a half-life of 12 to16 days. Pharmacokinetic profiles were similar to those in the Caucasian population. Tumor response data were available for all patients. A best response of stable disease (defined as a lack of progression at the first assessment at 8-weeks) was reported in 9 patients and progressive disease in 9 patients. Monocytes were found to express DR5, and showed a high degree of conatumumab receptor occupancy after treatment at all dose levels.

Conclusions: Conatumumab administered up to 20 mg/kg once every 2 weeks did not result in dose limiting toxicities in Japanese patients with advanced solid tumors. Adverse events and pharmacokinetics were similar to those in the first in human study conducted in the United States.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C6.

Analysis of biomarkers during early phase clinical development of AMG 479, an investigational fully human monoclonal antibody antagonist of type 1 insulin-like growth factor receptor (IGF-1R)

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Background: AMG 479 showed anti-tumor activity in a phase 1 (P1) and phase 1b (P1b) trial (Tolcher, J Clin Oncol. 2007;25:3002; Sarantopoulos, J Clin Oncol. 2008;26:3583). We sought to identify predictive markers of response to AMG 479 in these trials by analyzing pharmacodynamic (PD) markers in serum, and expression and mutations of regulators of the IGF-1R pathway in tumors. Methods: Patients (pts) had advanced solid tumors and received AMG 479 (1–20 mg/kg Q2W) in the P1 trial or AMG 479 (6 or 12 mg/kg Q2W) + panitumumab (6 mg/kg Q2W) or gemcitabine (1,000 mg/m2 QW) in the P1b trial. Serum levels of IGF-1 and IGFBP-3 were measured pre dose on Day -1 and post dose at various time points. In the P1 trial, we examined relationships between tumor response (by RECIST) and: 1) levels of IGF-1 and IGFBP-3 (at baseline or PD change from baseline); 2) somatic mutations in key genes (including K-ras, and PTEN) of the IGF-1R pathway (in archival tumors); and 3) expression of PTEN (measured by immunohistochemistry in archival tumors). Results: Serum IGF-1 and IGFBP-3 increased in a concentration-dependent manner between 1 and 12 mg/kg AMG 479, with an apparent plateau between 12 and 20 mg/kg AMG 479. Baseline and PD changes in IGF-1 and IGFBP-3 were not substantially different in pts with a tumor response compared with those without a tumor response. A partial response to AMG 479 was observed in a pt with an activating K-ras mutation. No responses have been observed in tumors that lack expression of PTEN. Conclusions: The PD results suggest near complete biochemical coverage at 12-mg/kg AMG 479. Our hypothesis-generating analyses suggest that: 1) pre and postdose levels of IGF-1 and IGFBP-3 do not predict response to single-agent AMG 479; 2) activating K-ras mutations do not appear to preclude responsiveness to single-agent AMG 479 (in contrast to EGFR inhibitors); 3) expression and mutations of regulators of the PI3K/Akt pathway downstream of IGF-1R activation may be useful in predicting response to AMG 479.

[Table: see text]

A randomized phase II study of bevacizumab (B) and gemcitabine (G) plus cetuximab (C) or erlotinib (E) in patients (pts) with advanced pancreatic cancer (PC): A preliminary analysis

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Background: In a phase II trial of G + anti-VEGF antibody B in 52 PC pts, we reported a 21% response rate and median survival of 8.8 months (mo) (Kindler, JCO 2005). EGFR inhibitors C and E also have activity in PC. VEGF and EGFR pathways are interdependent; dual inhibition may be synergistic. Methods: We are conducting a multi-center, randomized phase II trial of GBC vs. GBE in advanced PC pts who have: no prior therapy for metastatic disease, PS 0–2, measurable disease, no tumor invasion of duodenum, no bleeding risk. Primary endpoint: response. Trial design: 2 parallel, Simon 2-stage designs; requires 6 responses in 27 evaluable pts for 2nd stage; 63 pts/arm. All pts receive G 1000 mg/m2 over 30 minutes days (D) 1, 8, 15 Q28D; B 10 mg/kg D 1, 15 Q28D. Pts are randomized to C 400 mg/m2 D1, then 250 mg/m2 Q7D, or E 150 mg D1–5, 8–12, 15–26 Q28D. CT scans: Q2 cycles. 58 pts enrolled at 13 sites 9/04–12/05. Pt characteristics: male 66%; median age 61 (range 36–82); PS: 0/1/2: 52%/40%/8%; stage IV 95%; liver metastases 76%. Results: 49 pts (GBC/GBE 24/25) are evaluable for toxicity; 51 pts (27/24) for response. 232 cycles were administered (median 4, range 1–11). Grade ¾ toxicity (%pts GBC/GBE): neutropenia 29%/28%; anemia 4%/16%, thrombocytopenia 8%/24%, DVT-PE 17%/8%, CVA 4%/4%, GI bleed 4%/12%, hypertension 4%/4%, rash 13%/4%, pneumonitis 0%/8%, diarrhea 4%/4%; grade 5: bowel perforation 0%/4%, MI- CVA 0%/4%, other cardiac 4%/0%. Response: GBC 19% (1 complete, 4 partial), GBE 21% (5 partial). Stable disease 59%/67%. Median progression-free survival 3.6/3.6 mo (95%CI: 2.7, 4.7/2.7, 5.9), 6-month survival 41%/38% (95% CI: 11%, 71%/2%, 75%). Conclusion: GBC and GBE are active in advanced PC. Toxicity, principally related to B, is moderate. The trial proceeds to a 2nd stage if 1 more response is observed in each arm. Supported by NCI grant N01-CM-17102.

[Table: see text]

Bevacizumab (B) plus erlotinib (E) for patients (pts) with recurrent ovarian (OC) and fallopian tube (FT) cancer: Preliminary results of a multi-center phase II trial

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Background: The epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) are commonly over-expressed in OC and correlate with poor prognosis. The anti-VEGF antibody B and the EGFR tyrosine kinase inhibitor E have each demonstrated activity in OC. Dual inhibition with BE may overcome mechanisms of resistance encountered with either agent alone. Methods: We are conducting a 2-stage phase II trial of BE in pts with recurrent OC, primary peritoneal, and FT cancer. Eligible pts had ≤ 2 prior chemo regimens for recurrent or refractory disease; no prior VEGF or EGFR inhibitors; ECOG performance status (PS) 0–2; measurable disease; normal organ function; no proteinuria (<1000 mg/24 hours). B 15 mg/kg was given IV on day 1 every 21 days and daily E 150 mg PO was given continuously. CT scans were obtained every 9 weeks. 2 responses are required in the first stage to justify accrual into a second stage. Results: 13 pts enrolled at 3 centers from 7/05 to 10/05. Median age: 56 (range 45–70). PS (N with 0/1/2): 6/4/3. Primary site (N): OC 11, FT 2. Primary platinum response (N): refractory 4, resistant (<12 mo PFS) 2, sensitive (≥12 mo) 7. Total prior chemo regimens (N with 1/2/3): 1/8/4. 55 cycles of BE have been delivered (median 4, range 1–8). 12 pts are evaluable for response (1 too early). There has been 1 major response (8%). 8 patients (67%) had stable disease (SD). 1 pt with SD met 75% CA-125 response criteria. 8 pts remain on study. Median PFS has not been reached (median f/u 2.2 months). Attributable toxicities (N with grade 1/2/3/4): rash 4/7/0/0, diarrhea 6/1/2/0, stomatitis 3/1/0/0, myalgias 4/0/0/0, proteinuria 3/0/0/0, bilirubin 0/2/0/0. There were 2 bowel perforations (grade 3/4): both had 2 prior regimens, peritoneal implants >1 cm, 3 doses of B (last was 10 and 42 days prior), and small bowel obstructions in the preceding 28 days. Conclusions: The first stage of accrual is complete and further enrollment is on hold pending continued efficacy evaluation. There appeared to be an increased rate of bowel perforation, and identification of potential risk factors for this event would be critical for further development of this combination. Updated results will be presented. Supported by NCI Grant N01-CM-17102.

[Table: see text]

A clinical study of competency to consent to treatment in pediatrics

A 19-item competency questionnaire for pediatric patients (CQ-Peds) was used to evaluate competency to consent to treatment in pediatric outpatients and inpatients at two university hospitals. Sixty-nine consecutive English-speaking pediatric outpatients were studied at Hospital A, and 23 consecutive English-speaking pediatric inpatients were studied at Hospital B. Demographic data were statistically analyzed using the chi-square test, and there were no significant differences between the competent and incompetent groups (using CQ-Peds scores and cutoffs). CQ-Peds scores correlated highly with age (r = .947, p < .003; Outpatient Hospital A). Using the Child Behavior Checklist (CBCL) and the Pediatric Symptom Checklist (PSC) as a screen for psychopathology, the presence of psychiatric disturbance, per se, did not correlate with low CQ-Peds scores, nor was there a statistical difference between children from Spanish-speaking households and those from English-speaking households (Inpatient Hospital B). Overall, the children scored well on the CQ-Peds and demonstrated a good appreciation for their illnesses and treatment. The CQ-Peds score correlated highly with the that on the Wechsler Intelligence Scale for Children Revised Edition (WISC-R) vocabulary, comprehension, and similarities subtests and also with the Wide-Range Achievement Test-III (WRAT-III) reading assessment score (Inpatient Hospital B).

Pantethine inhibits the formation of high-Tc protein aggregates in gamma B crystallin solutions

PURPOSE

Solutions of the bovine lens protein gamma B (or gamma II) crystallin at neutral pH in the absence of reducing agents, undergo a slow, partial conversion to a new protein species, gamma IIH. This species is an aggregate composed of an intermolecular, disulfide-crosslinked dimer (approximately equal to 32% of total protein by weight) and loosely associated dimers (approximately equal to 66%). gamma IIH has a phase separation temperature (Tph), at least 40 degrees C higher than that of native gamma II crystallin at any given protein concentration. In this paper we demonstrate that pantethine, a derivative of coenzyme A, inhibits the formation of gamma IIH.

METHODS

gamma II crystallin solutions were incubated at pH 7.1 and room temperature with increasing amounts of pantethine. The Tph of the solutions was monitored as a function of incubation time. Corresponding to each Tph measurement, aliquots of each solution were analyzed by cation-exchange HPLC to determine the amount of gamma IIH formed.

RESULTS

Incubation of gamma II crystallin with increasing amounts of pantethine lowers Tph and suppresses the formation of gamma IIH. With pantethine to protein mole ratios of 0.66, 1 and 2, the Tph of gamma II crystallin is lowered from 8 degrees C in the native protein, to 2 degrees C, -3 degrees C respectively, at a protein concentration of approximately equal to 200 mg/ml. The amount of gamma IIH accumulated decreases from approximately 25% in the native protein to 10%, 1% and 0% respectively in these pantethine-treated protein solutions. For complete suppression of the rise in Tph and inhibition of gamma IIH formation, a 2:1 mole ratio of pantethine to protein is required.

CONCLUSIONS

We suggest that pantethine reacts with two cysteine residues of gamma IIH crystallin by forming a mixed disulfide, and effectively suppress protein aggregation and lowers Tph. This is due to the strong polar character of pantethine which reduces the net attractive interactions between the protein molecules.