Blaney, Susan M.

10017 Background: In preclinical models, temozolomide (TMZ) and vincristine (VCR) are synergistic with irinotecan (IRN). We sought to determine the dose limiting toxicities (DLTs) and maximum tolerated dose (MTD) of orally administered IRN given on two different schedules together with TMZ and VCR in children with refractory solid tumors, using cefixime to reduce IRN-associated diarrhea. Methods: Schedule A: Oral IRN daily for 5 days for 2 weeks (dx5x2), with VCR 1.5 mg/m2 on days 1 and 8 and TMZ 100 mg/m2 on days 1 - 5. Schedule B: Oral IRN daily for 5 days for 1 week (dx5x1) with VCR 1.5 mg/m2 on day 1 and TMZ 100 - 150 mg/m2 on days 1 - 5. Courses were repeated every 3 weeks. A standard cohorts of 3 + 3 design was used. Results: On Schedule A, 18 evaluable patients (median age 15 yrs, range 3 - 21) received 55 courses. At IRN 50 mg/m2/day, 4/12 pts had DLT (hepatotoxicity, abdominal pain, anorexia, hypokalemia, and thrombocytopenia). The oral IRN MTD on this dx5x2 schedule was 35 mg/m2/d (1/6 pts with DLT of hypoalbuminemia). On Schedule B, 18 evaluable patients (median age 9 yrs, range 3–21) received 71 courses of oral IRN 70 - 90 mg/m2/d x 5 with TMZ 100 - 150 mg/m2/d x 5. At oral IRN 90 mg/m2/d with TMZ 150 mg/m2/d, 0/6 pts had DLT, and no Grade 4 toxicities were seen. No further doses were explored. First-course and cumulative toxicity appeared worse with Schedule A, including 3 patients with responding or stable tumors who withdrew due to fatigue, nausea, and weight loss. UGT1A1*28genotype did not correlate with DLT. At the oral IRN MTD of 90 mg/m2/d, the median SN-38 AUCinf was 72 ng/ml*h. One patient with osteosarcoma had a confirmed partial response. Unconfirmed complete and partial responses were seen in 2 Ewing sarcoma patients. Eight additional patients received > 6 courses, including 2 each with neuroblastoma and medulloblastoma. Conclusions: The dx5x1 schedule of VOIT was well tolerated, with SN-38 exposures similar to those achieved with intravenous IRN. Activity on this and prior studies suggests a potential role for VOIT in sarcoma patients. No significant financial relationships to disclose.

2538 Background: Trebananib is a first-in-class peptibody (peptide-Fc fusion protein) that selectively inhibits Angiopoietin 1 and Angiopoietin 2 to inhibit interaction with the Tie2 receptor tyrosine kinase and prevent angiogenesis by a VEGF independent mechanism. A pediatric phase 1 trial was performed to define the dose limiting toxicities (DLT), maximum tolerated dose (MTD) and pharmacokinetics (PK) of trebananib. Methods: Trebananib was administered as a weekly 30 - 60 minute IV infusion. Three dose levels (10, 15 or 30 mg/kg/dose) were evaluated using a rolling-six design. PK sampling and analysis of peripheral blood biomarkers was performed during the first 4 weeks of therapy. Results: Fifteen eligible patients (14 evaluable for toxicity) with a median age of 14 yrs (range, 3 to 20) and diagnoses of neuroblastoma (n=4), rhabdomyosarcoma (n=3), Ewing sarcoma (n=3), osteosarcoma (n=2), other soft tissue sarcoma (n=2), or nasopharyngeal carcinoma (n=1) have been enrolled. There were no DLTs observed at either the 10 mg/kg (n=6 pts) or 15 mg/kg (n=3 pts) dose. 1/6 pts receiving 30 mg/kg/dose developed DLT (venous thrombosis at a central line site). Non-dose limiting grade 3 or 4 toxicities included lymphopenia (n=2) hypertension (n=1), and neutropenia (n=1). Response in evaluable patients after eight weeks of therapy included stable disease (n=6 pts) and progressive disease (n=7 pts). PK were linear over the 3 dose levels, with t1/2 and Clpvalues of 69±18 h and 1.6±0.5 ml/h/kg, respectively. Conclusions: Trebananib is well tolerated in pediatric patients with recurrent or refractory solid tumors with recommended Phase 2 dose of 30 mg/kg. Correlative biology studies will be presented. Further study is planned to evaluate tolerability and changes in vascular permeability in patients with primary CNS tumors. Clinical trial information: NCT01538095.

9581 Background: AKT, a serine threonine protein kinase, is activated downstream of phosphatidylinositol 3-kinase (PI3K) which transmits signals from cytokines, growth factors and oncoproteins to multiple targets. Activated AKT regulates survival, proliferation, and growth. The PI3K/AKT pathway is downstream of most of the common growth factor tyrosine kinase receptors in cancer, e.g., EGFR, HER2, IGFR, etc., and is a driver of tumor progression in many cancers. AKT protein kinase is activated in many pediatric solid tumors, including glioblastoma, malignant rhabdoid tumors, neuroblastoma, synovial sarcoma, rhabdomyosarcoma and medulloblastoma. MK2206, an oral allosteric AKT1, 2,3 inhibitor, has demonstrated antitumor activity in in vitro and in vivo cancer models.A phase I trial evaluating MK2206 was conducted in children with refractory solid tumors. Methods: Using a rolling-6 design, MK2206 was administered either once every 7 days (schedule 1), or once every other day (schedule 2) in a 28-day cycle. Serial PK studies were obtained on day 1, cycle 1 and trough samples were obtained on days 7, 14, 21 and 28. Biological studies included analysis of PI3K/PTEN/AKT-cell signaling pathway in pre and post-therapy in PBMC and in tumors at diagnosis or recurrence. Results: Forty-five patients [23 males, median age 13.6 years (range 3.1-21.9)] with malignant glioma (14), ependymoma (4), hepatocellular carcinoma (3), gliomatosis cereberi (2) or other tumors (22) were enrolled; 34 were fully evaluable for toxicity (schedule 1 n=17; 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. There were no DLTs at 35 mg/m2 and dose level 4 (58 mg/m2) is currently open for patient accrual with one enrollment. 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. Conclusions: The recommended pediatric phase II dose of weekly MK2206 is 120 mg/m2 and the last cohort of patients to the every other day dosing schedule of MMK206 is enrolling. PK and PD data are currently being analyzed and will be presented.

9019 Background: Pemetrexed is a new multi-targeted antifol that inhibits enzymes involved in the de novo biosynthesis of thymidine and purine nucleotides. Methods: A phase 1 dose escalation and pharmacokinetic study (PK) was performed in children with refractory solid tumors to define the dose limiting toxicities (DLTs) and a recommended phase 2 dose. Pemetrexed was administered as a 10 min iv infusion every 21 days. All patients received folic acid (400 mcg/day po), vitamin B12 (500–1000 mcg every 3rd course IM) and dexamethasone (0.1 mg/kg/dose bid × 3 days each course) . Cohorts of 3 to 6 children were enrolled at dose levels of 400, 520, 670, 870, 1,130, 1,470, 1,910 and 2,480 mg/m2. DLT was defined as any Gr. 3 or 4 non-hematological toxicity (except nausea/vomiting, alopecia, or AST/ALT elevation that returns to Gr. 1), Gr. 4 neutropenia or Gr. 4 thrombocytopenia ≥ 7 days. Results: 33 subjects (31 fully evaluable for toxicity), median age of 12 yrs (range, 1–21), with diagnoses including osteosarcoma (12), Ewing’s sarcoma (3), hepatoblastoma (2), renal cell carcinoma (2), brainstem glioma (3), glioma (3), and other (n=8) were enrolled. DLT occurred in 1/6 patients at 1,470 mg/m2 (Gr. 3 AST and ALT), and in 2/4 at 2,480 mg/m2 (Gr. 3 ANC and Gr. 3 rash in both). Other DLTs at 2,480 mg/m2 that occurred in 1 patient included Gr. 3 diarrhea and rectal hemorrhage, and Gr. 4 thrombocytopenia, lipase, GGT, hypophosphatemia, hypokalemia and hyponatremia. At 1,910 mg/m2, 0/6 patients had DLT. The median number of courses administered was 1 (range 1 to 17). No CRs or PRs have been observed. Results of PK and other correlative studies will be presented. Conclusions: The recommended phase 2 dose of pemetrexed for children and adolescents with recurrent solid tumors is 1,910 mg/m2 administered q21 days with dexamethasone, folic acid and B12 supplementation. A phase II COG study is planned. No significant financial relationships to disclose.

9018 Background: A pediatric phase I study of 17-allylaminogeldanamycin (17-AAG), an Hsp90 inhibitor, was conducted to determine the dose limiting toxicities (DLTs), the recommended phase II dose, the pharmacokinetics (PK), and to evaluate a surrogate marker for Hsp90 inhibition in peripheral blood mononuclear cells (PBMCs). Methods: Cohorts of 3–6 pts were enrolled at dose levels of 150, 200, 270 and 360 mg/m2/dose, administered as a 60 min infusion, on days 1, 4, 8 and 11 of a 21-day cycle. PK and PBMC evaluations were done during the first course of therapy. Results: 17 pts (7 male), median 7 yrs of age (range 1–19), were enrolled. 5 pts who developed PD prior to completing a full cycle of therapy were not considered evaluable for toxicity. No DLTs occurred. Non-DLTs included elevated transaminases (n=6), anemia (n=3), and vomiting (n=3). Based on the adult recommended dose and challenges posed by infusing the large volumes of DMSO, dose escalation was stopped at dose level 4. No CRs or PRs were observed; 3 patients remain on therapy at 6, 7 and 9 months with SD. One patient with hepatoblastoma had a reduction in AFP and SD over 3 cycles. PK data is available from the initial 3 dose levels. Drug exposure increases in proportion to dose for both17-AAG and its metabolite 17-AG. At 270 mg/m2/dose the Cmax and AUC of 17-AAG were 5,303 ± 1,591 ng/ml and 13,150 ± 5,086 ng/ml*hr, respectively, similar to the exposure in adults. The mean terminal half-life for 17-AAG was 3.0 ± 0.5 hrs. Induction of Hsp72, a surrogate marker for inhibition of Hsp90 was detected at all dose levels. Conclusions: The recommended phase II dose of 17AAG is 360mg/m2/day. Non-DMSO formulations may allow for further dose escalation in children and should be studied. No significant financial relationships to disclose.

9017 Background: Bevacizumab is a humanized monoclonal antibody targeting the vascular endothelial growth factor (VEGF-A) that has demonstrated significant growth inhibition in several pre-clinical models of pediatric solid tumors. However, the agent has never been tested in pediatric patients. Methods: A phase I dose escalation study in children with refractory solid tumors was conducted to define the dose limiting toxicities (DLTs), and to determine the pharmacokinetics (PK) and recommended phase II dose of bevacizumab administered by IV infusion every 2 weeks in 28-day cycles. Cohorts were enrolled at dose levels of 5, 10, and 15 mg/kg; the final dose level was expanded to include at least 3 children <6 years of age. Serial blood samples were collected for PK, plasma VEGF concentration, and circulating mature and progenitor endothelial cells (CECs/CEPs). Results: 20 patients (10 male), median age 13 yrs (range 1–21), were enrolled at dose levels 5 (n=3), 10 (n=3), and 15 (n=14) mg/kg. 18 patients were fully evaluable for toxicity (one withdrew consent prior to treatment and the second was removed for rapid disease progression). A total of 67 cycles were administered with a median of 3 per patient (range 1–16). Treatment was well tolerated and no DLTs were observed. Only one grade 3 toxicity, lymphopenia, was attributed to drug. Non-dose limiting, grade 1–2 toxicities included infusional reaction (n=3), rash (n=3), mucositis (n=2), and proteinuria (n=3). There was no hypertension, hemorrhage or thrombosis reported. There were no partial or complete responses; 3 pts with Ewings and 2 pts with soft tissue sarcoma had disease stabilization for > 3 months. The serum exposure to bevacizumab as measured by AUC appeared to increase in proportion to dose. The median clearance of bevacizumab was 4.1 ml/day/kg (range 3.2–15.9), and the median T1/2 was 11.8 days (range 3.9–14.6). In some patients, a rapid rate of rise in plasma VEGF, increase in mature CECs or decrease in CEPs was observed. Conclusion: Bevacizumab at doses up to 15mg/kg every two weeks is well tolerated in children with solid tumors. No significant financial relationships to disclose.

9014 Background: MGd, a radiosensitizer that selectively accumulates in tumors, generates reactive oxygen species intracellularly. In preclinical experiments, MGd enhances RT-induced apoptosis. Methods: A multi-institutional Phase I dose escalation and pharmacokinetic (PK) study was performed in children with newly diagnosed BSG to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of MGd administered i.v. 2 to 5 hours prior to involved field radiotherapy (RT) (1.8 Gy/day, total 54 Gy). Cohort 1 received MGd, 1.7 mg/kg/dose M-F × 3 wks and cohort 2 received the same dose M, W and F × 6 wks. The 6 subsequent cohorts of 3 to 6 pts received MGd M-F × 6 weeks at doses of 1.9, 3.4, 4.4, 5.5, 7.1 and 9.2 mg/kg/dose. Serum for PK analysis, and MRI scans (MGd is detectable by MR), were obtained for analysis of drug accumulation and responses. Results: 44 pts (42 fully evaluable for toxicity) with a median age of 6 years (range 2–20) were enrolled. At the 9.2 mg/kg/dose, 2/2 pts experienced DLT. During subsequent expansion of the 7.1 and 5.5 mg/kg/dose cohorts, DLTs, including transaminitis, hypertension and urticaria, were observed in 2/5 and 2/6 pts. At the MTD of 4.4 mg/kg/dose, 1/6 pts had reversible grade 3 serum transaminase elevations. PK analysis showed biphasic elimination with a terminal t 1/2 of 6.4 h. At the MTD, serum MGd concentrations were >250 ng/ml for 24 h. Serum clearance and steady-state volume of distribution were 0.0243 L/h/kg and 0.162 L/kg. MRI for intra-tumoral MGd distribution is ongoing. One patient had a CR and 4 had a PR. The estimated median survival is 10.3 months (95% confidence interval: 8.1 months-11.5 months). Conclusions: The recommended phase II dose of MGd for children with BSG is 4.4 mg/kg/d administered M-F × 6 weeks with involved field RT. A COG phase II trial is planned. [Table: see text]

9569 Background: Vorinostat, an orally administered histone deacetylase inhibitor, has potent antitumor activity against human cell lines in vitro (IC50 0.5 to 5 μM) and in xenograft models. A phase I trial of vorinostat was conducted in children with recurrent or refractory solid tumors to determine the maximum tolerated dose (MTD), dose limiting toxicity (DLT), pharmacokinetics (PK) of vorinostat, and to assess accumulation of histone acetylation in peripheral blood mononuclear cells (PBMCs). Methods: Vorinostat was administered once daily at dose levels of 180, 230, and 300 mg/m2/d. Courses were 28 days in duration, without interruption. PK analysis was performed during the 1st course. Vorinostat's ability to induce acetyl-histone (H3) accumulation in vivo was studied by western blot analysis. Results: 30 patients, 17 males, median age 15 years (range 4–21), were enrolled; 24 patients were fully evaluable for toxicity. At 180 mg/m2/d, 1/6 pts developed DLT (deep vein thrombosis) and at 230 mg/m2/d 1/6 pts developed DLT (hypokalemia). At 300 mg/m2/d, DLTs consisted of reversible hypokalemia (n=1), neutropenia (n=1) and thrombocytopenia (n=2), defining the MTD as 230 mg/m2/d. Other non-dose limiting grade 3 or 4 toxicities included elevated ALT/AST, hyperbilirubinemia, leucopenia, and lymphopenia. Western blot analysis of PBMC protein isolates found clear evidence of dose- dependent accumulation of acetylated H3 histones. 1 patient with a spindle cell sarcoma received 8 courses and 1 patient with a low-grade astrocytoma had an unconfirmed minor response. Conclusions: Vorinostat is well tolerated in children with recurrent or refractory solid tumors and inhibits histone deacetylase activity in PBMC. The recommended phase II dose for children with solid tumors is 230 mg/m2/d. No significant financial relationships to disclose.

9563 Background: Both temozolomide (TEM) and vincristine (VCR) can increase the preclinical activity of low-dose protracted irinotecan (IRN) against pediatric solid tumors. Because these drugs have different dose-limiting toxicities (DLTs) and mechanisms of action, we combined these three agents and sought to determine the maximum tolerated dose (MTD) of orally administered IRN when given with fixed- dose TEM and VCR in children with relapsed or refractory solid tumors, using the antibiotic cefixime to reduce IRN-associated diarrhea. Methods: We studied two dose levels of oral IRN (35 or 50 mg/m2) administered on days 1–5 and 8–12, combined with oral TEM 100 mg/m2 on days 1–5 and intravenous VCR 1.5 mg/m2 on days 1 and 8. Courses were repeated every 21 days. Oral cefixime was started 5 days before chemotherapy and continued daily. Results: Of 21 patients enrolled, 17 (ages 3–21, median 14 yrs) were evaluable for toxicity and have to date received 46 courses (range 1–8, median 2). At the IRN dose of 50 mg/m2/d, 4 of 12 patients had DLT, including elevated ALT/AST (1), abdominal pain (1), hypokalemia (1), anorexia (1), thrombocytopenia (1), and fatal liver failure in a patient with metastatic disease in the liver and porta hepatis (1). In contrast, none of 5 patients treated at the dose of 35 mg/m2/d experienced first-course DLT, defining this dose as the MTD. UGT1A1 genotype did not correlate with DLT in this small trial. The median SN-38 lactone area under the curve (0–6h) at the IRN dose of 50 mg/m2/day was 13.5 ng/ml*h (range 3.8 to 30.9); pharmacokinetic analysis of patients treated at 35 mg/m2/day is ongoing. Six patients with the following tumors received more than 2 courses: neuroblastoma, ependymoma, hepatoblastoma, fibrillary astrocytoma, osteosarcoma, and Ewing sarcoma. Central review of response data is underway. Three patients continue on therapy at the MTD. Conclusions: Oral administration of IRN together with TEM and VCR was feasible and well tolerated at the MTD of 35 mg/m2 given dx5x2. Further study using a shorter 5-day course of oral IRN is planned. No significant financial relationships to disclose.

9513 Background: CD22, a 135kd protein restricted to B-cells, is expressed in > 90% of childhood B-precursor acute lymphoblastic leukemia (ALL). We conducted a feasibility/phase 2 study of epratuzumab, a humanized monoclonal antibody against CD22, with reinduction chemotherapy in children with relapsed CD22+ ALL. Methods: The feasibility portion (n=12) of the study is reported here. Patients with first or later ALL marrow relapse at any time following diagnosis, ± extramedullary disease, with = 25% blasts expressing CD22 and a presenting white blood cell count (WBC) of = 50,000/μl, were eligible. Therapy consisted of a 14-day single agent phase (epratuzumab 360 mg/m2 /dose IV twice weekly × 4 doses), followed by 4 weekly doses of epratuzumab in combination with standard reinduction chemotherapy (vincristine, prednisone, PEG-asparaginase, doxorubicin). Remission induction rates and minimal residual disease (MRD) by flow cytometry were determined at the end of this 6-week period. PK studies were performed by ELISA based immunoassay (prior + 30 minutes after infusions). Results: 12 evaluable patients, median age 10 years (range 3 - 18), were accrued. 9 pts were in 1st (n=5 early; n=4 late), and 3 pts in 2nd or later marrow relapse. The mean (±SD) trough epratuzumab concentration increased from 69±23 to 232±74 μg/ml during the initial 14 days. Surface CD22 was not detected by flow cytometry on peripheral blood leukemic blasts within 24 hours of drug administration in all but one patient, indicating effective targeting of leukemic cells by epratuzumab. The most frequent toxicities were grade 1–2 infusion reactions (n=9). Two dose limiting toxicities occurred: one patient had a Grade 4 seizure of unclear etiology and one patient had asymptomatic Grade 3 ALT elevation. 9 patients achieved a complete remission following chemoimmunotherapy, of whom 7 were MRD-negative. Conclusions: Treatment with epratuzumab plus standard reinduction chemotherapy is feasible and well tolerated in children with relapsed ALL, producing favorable early responses in the majority of patients. The phase II portion of the study is ongoing. [Table: see text]