Citations

e17017 Background: Epigenetic up-regulation of EBV and cellular genes via demethylation and histone deacetylase inhibition can induce EBV lytic replication enhancing immune mediated tumor killing and up-regulation of tumor suppressor genes resulting in tumor apoptosis. Methods: Patients (Pt) with relapsed or refractory NPC and NK-T cell lymphomas were enrolled to determine safety, tolerability, pharmacokinetics (PK), pharmacodynamics and preliminary anti-tumor activity using a dose escalation design. 5AC was administered on days 1 to 10 sub-cutaneously while SAHA was administered on days 1 to 14 orally. PK for SAHA, EBV viral load, characterization of circulating EBV, Immunohistochemistry (IHC) and EBV promoter methylation analysis in tumor tissue were performed. Results: 11 pt have been treated (M:F 8:3, median age 48, R: 35-71) at 3 dose levels – 5AC 50 mg/m2 and SAHA 200 mg b.i.d. (dose level 1), 5AC 37.5 mg/m2 and SAHA 200 mg q. am and 100 mg q. pm (dose level 2), and 5AC 25 mg/m2 and SAHA 100 mg b.i.d (dose level 3). Median number of previous treatment regimens was 3 (R:1-6). Dose limiting toxicities (DLT) were seen in 2/2 pts at dose level 1: grade 4 thrombocytopenia (1 pt), grade 3 nausea, vomiting and fatigue (2 pts), and grade 5 hepatic failure (1 pt). Two of six patients at dose level 2 experienced DLT: grade 3 fatigue (1 pt) and worsening of pre-existing Sweet’s Syndrome (1 pt). Common AEs (G1/2) included fatigue (73%), cough (64%), anorexia (55%), and injection site reaction (45%). One minor response was seen and 5 pt had prolonged stable disease (>16 weeks), including one patient for 88 weeks. Analysis of post-treatment tumor biopsies showed demethylation of EBV lytic cycle gene promoters after treatment. SAHA PK, IHC results for EBV gene expression in tumor tissue, EBV viral load and characterization of circulating EBV will be presented. Conclusions: 5AC/SAHA appears to be tolerable at dose level 3 with suggestion of clinical benefit. Analysis of post-treatment tumor and blood samples suggests that modulation of EBV gene expression may play a role in the mechanism underlying clinical benefit. Continued accrual at dose level 3 is ongoing. Clinical trial information: NCT00336063.

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.

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]

504 Background: CYP2D6 genetic variants and concurrent administration of potent inhibitors (Inh) of the enzyme markedly reduce the plasma concentrations of endoxifen (Jin. JNCI 2005;97:30–9). We have shown that genetic variation in CYP2D6 is associated with a higher risk of relapse in Tam treated patients (pts) (Goetz. JCO 2005;23:9312–18), but the impact of CYP2D6 inhibition on Tam clinical outcome is unknown. Methods: Using the North Central Cancer Treatment Group 89–30–52 adjuvant Tam trial (1989–1994), we evaluated the effect of co-administration of CYP2D6 Inh and CYP2D6*4 genotype on relapse in pts receiving tam alone. Patient charts were reviewed at each randomizing site to record the following known CYP2D6 Inh: fluoxetine (F), paroxetine (P), sertraline (S), cimetidine (C), amiodarone (A), doxepin (D), ticlopidine (T) and haloperidol (H). Poor metabolizers (PM) were defined as pts who were CYP2D6 *4/*4 and/or known to receive a CYP2D6 Inh. Intermediate metabolizers (IM) were defined as WT/*4 without CYP2D6 Inh, and extensive metabolizers (EM) as WT/WT without CYP2D6 Inh. The association between CYP2D6 status and Tam clinical outcome was determined using the log-rank test. Multivariate Cox modeling was performed using traditional prognostic factors. Results: CYP2D6*4 genotype was obtained in 190 of 256 eligible pts, with a CYP2D6*4/*4 genotype frequency of 6.8% as described previously (Goetz JCO 2005). Medication history was available in 171/256 eligible pts and in 143/190 pts with CYP2D6 genotype. Eleven of 173 patients were concomitantly administered these CYP2D6 Inh: F(2), P(2), S(2), H(1), C(4), and D(1). The median duration of use was 2.5 yrs. Twenty-four pts met criteria for PM [13 by *4/*4 genotype and 11 by CYP2D6 Inh (7 WT/WT, 1 WT/*4, and 3 unknown genotype)], 21 for IM, and 102 for EM. Compared with either IM or EM, PMs had significantly worse time to recurrence and disease free survival in both the univariate (HR 2.5, p=0.02; and 2.2, p=0.01) and multivariate (HR 2.7, p=0.01; and HR 2.2 p=.02) analyses utilizing tumor size, nodal status, and tumor grade. Conclusion: Our data indicate that CYP2D6 status can be used to identify pts who should receive tam therapy and tam treated pts should not be co-administered potent CYP2D6 inhibitors. No significant financial relationships to disclose.

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.