Blaney, Susan M.

BackgroundWe report results of a phase I trial designed to estimate the maximum tolerated dose (MTD), describe dose‐limiting toxicities (DLT), and characterize the pharmacokinetic profile of MK‐2206, an AKT inhibitor, in children with refractory or recurrent malignancies.ProcedureMK‐2206 was administered either every other day (Schedule 1), or once a week (Schedule 2) in a 28‐day cycle. Dose escalations in increments of ∼30% were independently made in each part using the rolling‐six design. Serial pharmacokinetic (PK) studies were obtained. Biological studies include analysis of PI3K/PTEN/AKT‐cell signaling pathway in pre and post‐therapy in PBMC and in tumors at diagnosis or recurrence.ResultsFifty patients (26 males, median age 12.6 years [range, 3.1–21.9]) with malignant glioma (16), ependymoma (4), hepatocellular carcinoma (3), gliomatosis cereberi (2), or other tumors (22) were enrolled; 40 were fully evaluable for toxicity (Schedule 1, n = 23; Schedule 2, n = 17). Schedule 1 DLTs included: grade 3 dehydration in 1/6 patients at 28 mg/m2; grade 4 hyperglycemia and neutropenia in 1/6 patients at 45 mg/m2; and grade 3 rash in 3/6 patients at dose level 4 (58 mg/m2). Schedule 2 DLTs included: grade 3 alkaline phosphatase in 1/6 patients at 90 mg/m2; grade 3 rash in 1/6 patients at 120 mg/m2; and grade 3 rash in 2/6 patients at 155 mg/m2.ConclusionsThe recommended pediatric phase 2 dose of MK‐2206 is 45 mg/m2/dose every other day or 120 mg/m2/dose weekly. PK appeared linear over the dose range studied. Pediatr Blood Cancer 2014;61:1246–1251. © 2014 Wiley Periodicals, Inc.

Abstract Purpose: Imetelstat is a covalently-lipidated 13-mer thiophosphoramidate oligonucleotide that acts as a potent specific inhibitor of telomerase. It binds with high affinity to the template region of the RNA component of human telomerase (hTERC) and is a competitive inhibitor of telomerase enzymatic activity. The purpose of this study was to determine the recommended phase II dose of imetelstat in children with recurrent or refractory solid tumors. Experimental Design: Imetelstat was administered intravenously more than two hours on days 1 and 8, every 21 days. Dose levels of 225, 285, and 360 mg/m2 were evaluated, using the rolling-six design. Imetelstat pharmacokinetic and correlative biology studies were also performed during the first cycle. Results: Twenty subjects were enrolled (median age, 14 years; range, 3–21). Seventeen were evaluable for toxicity. The most common toxicities were neutropenia, thrombocytopenia, and lymphopenia, with dose-limiting myelosuppression in 2 of 6 patients at 360 mg/m2. Pharmacokinetics is dose dependent with a lower clearance at the highest dose level. Telomerase inhibition was observed in peripheral blood mononuclear cells at 285 and 360 mg/m2. Two confirmed partial responses, osteosarcoma (n = 1) and Ewing sarcoma (n = 1), were observed. Conclusions: The recommended phase II dose of imetelstat given on days 1 and 8 of a 21-day cycle is 285 mg/m2. Clin Cancer Res; 19(23); 6578–84. ©2013 AACR.

Purpose Pazopanib, an oral multikinase angiogenesis inhibitor, prolongs progression-free survival in adults with soft tissue sarcoma (STS). A phase I pharmacokinetic and pharmacodynamic study of two formulations of pazopanib was performed in children with STS or other refractory solid tumors. Patients and Methods Pazopanib (tablet formulation) was administered once daily in 28-day cycles at four dose levels (275 to 600 mg/m 2 ) using the rolling-six design. Dose determination for a powder suspension was initiated at 50% of the maximum-tolerated dose (MTD) for the intact tablet. Ten patients with STS underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scanning at baseline and 15 ± 2 days after initiation of pazopanib at the tablet MTD. Results Fifty-three patients were enrolled; 51 were eligible (26 males; median age, 12.9 years; range, 3.8 to 23.9 years). Hematologic and nonhematologic toxicities were generally mild, with dose-limiting lipase, amylase, and ALT elevation, proteinuria, and hypertension. One patient with occult brain metastasis had grade 4 intracranial hemorrhage. The MTD was 450 mg/m 2 for tablet and 160 mg/m 2 for suspension. Steady-state trough concentrations were reached by day 15 and did not seem to be dose dependent. One patient each with hepatoblastoma or desmoplastic small round cell tumor achieved a partial response; eight patients had stable disease for ≥ six cycles, seven of whom had sarcoma. All patients with evaluable DCE-MRI (n = 8) experienced decreases in tumor blood volume and permeability (P < .01). Placental growth factor increased, whereas endoglin and soluble vascular endothelial growth factor receptor-2 decreased (P < .01; n = 41). Conclusion Pazopanib is well tolerated in children, with evidence of antiangiogenic effect and potential clinical benefit in pediatric sarcoma.

Abstract Purpose: Aflibercept is a novel decoy receptor that efficiently neutralizes circulating VEGF. A pediatric phase I trial was conducted to define the dose-limiting toxicities (DLT), maximum tolerated dose (MTD), and pharmacokinetics (PK) of aflibercept. Experimental Design: Cohorts of three to six children with refractory solid tumors received aflibercept intravenously over 60 minutes every 14 days, at 2.0, 2.5, or 3.0 mg/kg/dose. PK sampling and analysis of peripheral blood biomarkers were conducted with the initial dose. Results: Twenty-one eligible patients were enrolled; 18 were fully evaluable for toxicity. One of six patients receiving 2.0 mg/kg/dose developed dose-limiting intratumoral hemorrhage and two of six receiving 3.0 mg/kg/dose developed either dose-limiting tumor pain or tissue necrosis. None of the six patients receiving 2.5 mg/kg/dose developed DLTs, defining this as the MTD. The most common non-DLTs were hypertension and fatigue. Three patients with hepatocellular carcinoma, hepatoblastoma and clear cell sarcoma had stable disease for &gt;13 weeks. At the MTD, the ratio of free-to-bound aflibercept serum concentration was 2.10 on day 8 but only 0.44 by day 15. A rapid decrease in VEGF (P &lt; 0.05) and increase in placental growth factor (PlGF; P &lt; 0.05) from baseline was observed in response to aflibercept by day 2. Conclusions: The aflibercept MTD in children of 2.5 mg/kg/dose every 14 days is lower than the adult recommended dose of 4.0 mg/kg. This dose achieves, but does not sustain, free aflibercept concentrations in excess of bound. Tumor pain and hemorrhage may be evidence of antitumor activity but were dose-limiting. Clin Cancer Res; 18(18); 5081–9. ©2012 AACR.

Purpose A phase I/II study of cixutumumab (IMC-A12) in children with refractory solid tumors was conducted. This study was designed to assess the toxicities, pharmacokinetics, and pharmacodynamics of cixutumumab in children to determine a recommended phase II dose and to assess antitumor activity in Ewing sarcoma (ES). Patients and Methods Pediatric patients with relapsed or refractory solid tumors were treated with cixutumumab as a 1-hour intravenous infusion once per week. Two dose levels—6 and 9 mg/kg—were evaluated using a standard three-plus-three cohort design. Patients with refractory ES were treated in an expanded phase II cohort at each dose level. Results Forty-seven eligible patients with a median age of 15 years (range, 4 to 28 years) were enrolled. Twelve patients were treated in the dose-finding phase. Hematologic and nonhematologic toxicities were generally mild and infrequent. Dose-limiting toxicities included grade 4 thrombocytopenia at 6 mg/kg and grade 3 dehydration at 9 mg/kg. Mean trough concentration (± standard deviation) at 9 mg/kg was 106 ± 57 μg/mL, which exceeded the effective trough concentration of 60 μg/mL observed in xenograft models. Three patients with ES had confirmed partial responses: one of 10 at 6 mg/kg and two of 20 at 9 mg/kg. Serum insulin-like growth factor I (IGF-I) levels consistently increased after one dose of cixutumumab. Tumor IGF-I receptor expression by immunohistochemistry did not correlate with response in patients with ES. Conclusion Cixutumumab is well tolerated in children with refractory solid tumors. The recommended phase II dose is 9 mg/kg. Limited single-agent activity of cixutumumab was seen in ES.

Purpose The purpose of this study was to determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), and pharmacokinetics of vorinostat administered as a single agent and in combination 13-cis retinoic acid (13cRA) in children with refractory solid tumors; to evaluate the tolerability of the solid tumor MTD in children with refractory leukemias; and to characterize the pharmacokinetics of a vorinostat suspension in children. Patients and Methods Vorinostat was administered orally daily starting at 180 mg/m2/d with escalations planned in 30% increments. Pharmacokinetic studies were performed with the initial dose. Acetyl-histone (H3) accumulation was assessed by Western blotting of peripheral blood mononuclear cells (PBMC). Results Sixty-four patients were enrolled on this multipart trial. In patients with solid tumors, the MTD was 230 mg/m2/d with dose-limiting neutropenia, thrombocytopenia, and hypokalemia at 300 mg/m2/d. DLTs observed with the combination of 13cRA and vorinostat included thrombocytopenia, neutropenia, anorexia, and hypertriglyceridemia, resulting in a MTD of vorinostat 180 mg/m2/d 4 times per week and 13cRA 80 mg/m2/dose twice per day, days 1 through 14 every 28 days. Wide interpatient variability was noted in vorinostat disposition, with area under the concentration-time curves at 230 mg/m2/d for the capsule (range, 1,415 to 9,291 ng/mL × hr) and oral suspension (range, 1,186 to 4,780 ng/mL × hr). Significant accumulation of acetylated H3 histone in PBMC was observed after administration of vorinostat, particularly at higher doses. One patient with neuroblastoma experienced a complete response to the combination. Conclusion In children with recurrent solid tumors, vorinostat is well-tolerated at 230 mg/m2/d, with a modest dose reduction being required when combining vorinostat with 13cRA. Drug disposition is similar to that observed in adults.

Purpose To determine the tolerability and serum concentration of epratuzumab, a humanized monoclonal antibody targeting CD22, administered alone and in combination with reinduction chemotherapy in children with relapsed acute lymphoblastic leukemia (ALL), and to preliminarily assess tumor targeting and efficacy. Patients and Methods Therapy consisted of a single-agent phase (epratuzumab 360 mg/m2/dose intravenously twice weekly × four doses), followed by four weekly doses of epratuzumab in combination with standard reinduction chemotherapy. Morphologic and minimal residual disease (MRD) responses were determined at the end of this 6-week period. Serum concentrations of epratuzumab were determined before and 30 minutes after infusions, and CD22 targeting efficiency was determined by quantifying changes in CD22 expression after epratuzumab administration. Results Fifteen patients (12 fully assessable for toxicity) with first or later CD22-positive ALL marrow relapse enrolled on the feasibility portion of this study from December 2005 to June 2006. Two dose-limiting toxicities occurred: one grade 4 seizure of unclear etiology and one asymptomatic grade 3 ALT elevation. In all but one patient, surface CD22 was not detected by flow cytometry on peripheral blood leukemic blasts within 24 hours of drug administration, indicating effective targeting of leukemic cells by epratuzumab. Nine patients achieved a complete remission after chemoimmunotherapy, seven of whom were MRD negative. Conclusion Treatment with epratuzumab plus standard reinduction chemotherapy is feasible and acceptably tolerated in children with relapsed CD22-positive ALL. CD22 targeting was efficient, and the majority of patients achieved favorable early responses.

Purpose We conducted a pediatric phase I trial of the vascular endothelial growth factor (VEGF)–neutralizing antibody bevacizumab (BV). Primary aims included estimating the maximum-tolerated dose (MTD) and determining the dose-limiting toxicities (DLTs), pharmacokinetics, and biologic effects of BV in children with cancer. Patients and Methods BV (5, 10, 15 mg/kg) was administered intravenously every 2 weeks in 28-day courses to children with refractory solid tumors. Results Twenty-one patients enrolled, 20 (median age, 13 years) were eligible, and 18 completed one course and were fully assessable for toxicity. A total of 67 courses were administered (median, three courses per patient; range, one to 16 courses). Treatment was well tolerated with no DLTs observed. Non-DLTs included infusional reaction, rash, mucositis, proteinuria, and lymphopenia. Increases in systolic and diastolic blood pressure not meeting Common Terminology Criteria for Adverse Events (CTCAEv3) pediatric-specific criteria for hypertension were observed. There was no hemorrhage or thrombosis. Growth perturbation was not detected in a limited sample over the first course. The serum exposure to BV as measured by area under the concentration-time curve (AUC) seemed to increase in proportion to dose. The median clearance of BV was 4.1 mL/d/kg (range, 3.1 to 15.5 mL/d/kg), and the median half-life was 11.8 days (range, 4.4 to 14.6 days). No objective responses were observed. Exploratory analyses on circulating endothelial mobilization and viability are consistent with the available adult data. Conclusion BV is well tolerated in children. Phase II pediatric studies of BV in combination with chemotherapy in dosing schedules similar to adults are planned.