Phase 1 trial of temsirolimus in combination with irinotecan and temozolomide in children, adolescents and young adults with relapsed or refractory solid tumors: a Children's Oncology Group Study

BACKGROUND

mTOR inhibitors have activity in pediatric tumor models. A phase I trial of the mTOR inhibitor temsirolimus (TEM) with irinotecan (IRN) and temozolomide (TMZ) was conducted in children with recurrent/refractory solid tumors, including central nervous system (CNS) tumors.

METHODS

Escalating doses of intravenous (IV) TEM were administered on days 1 and 8 of 21-day cycles. IRN (50 mg/m(2)/dose escalated to a maximum of 90 mg/m(2)/dose) and TMZ (100 mg/m(2)/dose escalated to a maximum of 150 mg/m(2)/dose) were administered orally (PO) on days 1-5. When maximum tolerated doses (MTD) were identified, TEM frequency was increased to weekly.

RESULTS

Seventy-one eligible pts (median age 10.9 years, range 1.0-21.5) with neuroblastoma (16), osteosarcoma (7), Ewing sarcoma (7), rhabdomyosarcoma (4), CNS (22) or other (15) tumors were enrolled. Dose-limiting hyperlipidemia occurred in two patients receiving oral corticosteroids. The protocol was subsequently amended to preclude chronic steroid use. The MTD was identified as TEM 35 mg/m(2) IV weekly, with IRN 90 mg/m(2) and TMZ 125 mg/m(2) PO on days 1-5. At higher dose levels, elevated serum alanine aminotransferase and triglycerides, anorexia, and thrombocytopenia were dose limiting. Additional ≥ grade 3 regimen-related toxicities included leukopenia, neutropenia, lymphopenia, anemia, and nausea/vomiting. Six patients had objective responses confirmed by central review; three of these had sustained responses through ≥ 14 cycles of therapy.

CONCLUSION

The combination of TEM (35 mg/m(2)/dose IV weekly), IRN (90 mg/m(2)/dose days 1-5) and TMZ (125 mg/m(2)/dose days 1-5) administered PO every 21 days is well tolerated in children. Phase 2 trials of this combination are ongoing.

Phase I and pharmacokinetic (PK) study of lenalidomide (LEN) in pediatric patients with relapsed/refractory solid tumors or myelodysplastic syndrome (MDS): A Children's Oncology Group Phase I Consortium study

10023

Background: LEN, which has immunomodulatory, antiangiogenic, and antiproliferative effects, is indicated for the treatment of adults with MDS and multiple myeloma. We report the final results of a phase 1 and PK study of LEN in children with recurrent or refractory solid tumors (ST) or MDS. Methods: LEN was administered by mouth once daily for 21 of 28 days. Cohorts of 3 to 12 children with ST were enrolled at 15, 25, 40, 55 and 70 mg/m2/d dose levels. Children with MDS received a fixed dose of 5 mg/m2/d. PK and correlative biology studies were performed in cycle 1. Results: 49 patients (23 female), median age 16 years (range, 1–21) were enrolled and received a median of 1 cycle (range 1–11). 39/46 ST patients and 3/3 MDS patients were fully evaluable for toxicity. 0/3 patients with MDS had DLT. At 15 mg/m2/d, 1/6 ST patients developed DLT (Gr 3 hypercalcemia). At 25 mg/m2/d 1 patient had a cerebrovascular ischemic event of uncertain relationship to LEN; future subjects were screened for thromboembolic risk factors prior to enrollment. At 40 mg/m2/d 3/12 patients developed DLTs (Gr 3 hypophosphatemia/hypokalemia; Gr 4 neutropenia delaying the start of the next cycle for > 7 days; Gr 3 somnolence); at 55 mg/m2/d 1/6 patients developed DLT (Gr 3 urticaria). At 70 mg/m2/d 0/6 patients had DLT. No further dose escalation was attempted. No objective responses were observed. LEN enhanced IL-2 and IL-15 concentrations; NK expansion and activation; and NK and LAK cytotoxicity (Ayello, ASH, 2008). The median apparent LEN clearance and half-life were 135 ± 45 ml/min/m2 and 2.3 ± 1.1 hr. Conclusions: LEN is well tolerated at doses up to 70 mg/m2/d x 21d of 28 days in children with recurrent or refractory ST. Enhancement of immune function is significant. PK parameters in children are similar to those in adults.

No significant financial relationships to disclose.

A phase I trial and pharmacokinetic study of IMC-A12 in pediatric patients with relapsed/refractory solid tumors: A Children's Oncology Group Phase I Consortium study

10013

Background: IMC-A12, a fully human IgG1 monoclonal antibody to the Insulin-Like Growth Factor-I Receptor (IGF-IR), is active preclinically in a variety of pediatric solid tumors. We performed a phase I trial to determine the toxicities, maximum tolerated dose (MTD), pharmacokinetics (PK), and pharmacodynamics (PD) of IMC-A12 in children with refractory solid tumors. Methods: IMC-A12 was administered as a weekly 1 hr IV infusion, without interruption. Two dose levels, 6 and 9 mg/kg, were evaluated using a standard 3+3 cohort design. After defining initial safety, patients (pts) with refractory Ewing sarcoma (ES) were treated in an expanded cohort at each dose level. Results: 24 eligible patients (11 male), median 15.3 yrs (range, 7.0 to 21.5), were enrolled. Among the 12 pts enrolled on the dose-escalation component, DLT (grade 4 thrombocytopenia) occurred in 1/6 pts at 6 mg/kg. No DLTs occurred in 6 pts at 9 mg/kg or in the ES cohort. 1/10 evaluable pts with ES at the 6 mg/kg dose had a partial response; no CRs were observed. Grade 2 or higher non-DLTs possibly attributable to IMC-A12 observed in the first course include anemia (n=4), leukopenia (n=1), lymphopenia (n=2), neutropenia (n=2), opportunistic infection (n=1), ↑liver transaminases (n=2), and hyperglycemia (n=1). No ≥ grade 3 hyperglycemia occurred. Mean (± SD) trough IMC-A12 concentrations were 59.8 ± 31.1 and 117 ± 70.8 μg/ml at the 6 and 9 mg/kg dose levels, respectively. A majority of pts at both dose levels exhibited > 50% reduction in PBMC IGF-IR protein levels. Conclusions: In order to exceed target trough concentrations associated with optimal anti-tumor activity in pre-clinical models, 9 mg/kg IV weekly is the recommended Phase II IMC-A12 dose in children. A phase II protocol for children with refractory solid tumors will be performed.

[Table: see text]

Phase I trial and pharmacokinetic study of two schedules of vincristine, oral irinotecan, and temozolomide (VOIT) for children with refractory solid tumors: A Children's Oncology Group Phase I Consortium study

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.

Phase I study of sorafenib in children with refractory solid tumors: A Children's Oncology Group Phase I Consortium trial

10012

Background: Sorafenib, an oral multitargeted kinase inhibitor, is indicated for treatment of adults with refractory renal cell or hepatocelluar carcinoma. We performed a phase I trial to determine the toxicities, maximum tolerated dose (MTD), pharmacokinetics (PK), and pharmacodynamics (PD) of sorafenib in children with refractory solid tumors. Methods: Sorafenib was administered q12h for 28 consecutive day cycles. Cohorts of 3–12 patients were enrolled at 105, 130, 150, 200, and 250 mg/m2/dose dose levels. Results: 34 eligible pts [16M, median age 14.6 yrs, (range, 5–21)] with osteosarcoma (n = 8), rhabdomyosarcoma (n = 3), other sarcomas (n = 13), hepatoblastoma (n = 3), or other solid tumors (n = 7) received 1–22 cycles (median 2). Grade 3 dose-limiting toxicity (DLT) occurred in 4/6 pts at the starting dose (150 mg/m2) and included hypertension (n = 1), rash/urticaria (n = 1), back pain (n = 1), thrombocytopenia (n = 1) and ALT/AST (n = 1). No DLTs were observed at 105 (n = 6) or 130 (n = 3) mg/m2, and the dose was re-escalated to 150 mg/m2 with modified eligibility criteria (normal ALT) and revised guidelines for grading and management of hypertension. Gr 3 DLTs occurred in 1/6 pts (lipase) at 150 mg/m2 and 2/2 pts (hyponatremia, hand-foot syndrome) at 250 mg/m2. At 200 mg/m2 only 1/6 pts experienced DLT (gr 3 ALT). No objective responses were observed, but 2 pts had tumor shrinkage. Sorafenib AUC did not increase proportionally with dose - the mean AUC0–24h was similar at 150 mg/m2 (28±24 μg · h/mL, n = 9) and 200 mg/m2 (28±17 μg · h/mL, n = 4). Tmax was prolonged and variable (10±11 h, n = 19). Plasma VEGFR (n = 13) decreased from 9.9±1.6 ng/mL at baseline to 8.3±1.7 ng/mL by d 28 (p < 0.001). Conclusions: The MTD of sorafenib in children with solid tumors is 200 mg/m2, similar to the adult recommended dose (400 mg).

No significant financial relationships to disclose.

A phase I trial of vorinostat in children with refractory solid tumors: A Children's Oncology Group Study

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.

A phase I study of zoledronic acid and low dose cyclophosphamide in children with recurrent/refractory neuroblastoma: A New Approaches to Neuroblastoma Therapy (NANT) study

9572

Background: Zoledronic acid (ZA), is a new generation, highly potent bisphosphonate that delays progression of bone metastases in adult malignancies. Bone metastases occur in 60% of children with advanced neuroblastoma. Pre-clinical studies demonstrated ZA with low dose chemotherapy delayed progression of osteolytic neuroblastoma lesions in a xenograft mouse model, prompting a phase I trial of ZA in neuroblastoma. Methods: Three dose levels of intravenous ZA (2, 3 or 4 mg/m2) administered every 28 days were evaluated in combination with continuous daily oral cyclophosphamide (CTX) (25 mg/m2/day) in patients with recurrent/refractory neuroblastoma and cortical bone lesions. The primary objective was to determine a recommended dose of ZA for future trials. Serial blood and urine samples were collected for pharmacokinetics, markers of osteoclast activity, and immunologic assays. Results: 14 patients (9 male), median age 7.9 years (0.8 - 26.6 years), were enrolled at ZA dose levels 2 mg/m2 (n=4), 3 mg/m2 (n=3), and 4 mg/m2 (n=7). To date, 13 patients are evaluable for toxicity. Thirty-nine cycles were administered with a median of 1 cycle per patient (range 1 - 12). Treatment was well tolerated; one DLT (Grade 3 hypophosphatemia) occurred at 4 mg/m2 ZA. Other grade 3 or 4 toxicities attributable to the combination included hypocalcemia (n=2), elevated transaminases (n=2), neutropenia (n=2), anemia (n=1), lymphopenia (n=1), and hypokalemia (n=1). Hypocalcemia occurred in 69% of first cycles and 8% of subsequent cycles. There were no renal toxicities or dental complications. There have been 2 partial responses by MIBG (central review pending), 4 stable disease, and 7 progressive disease; one patient is too early for response. Pharmacokinetic and correlative biology study results are pending. Conclusions: ZA is well tolerated and had evidence of responses when given with low dose CTX to children with recurrent/refractory neuroblastoma. The recommended dose of ZA for subsequent study is 4 mg/m2. Future studies incorporating ZA into the regimen for children with NB and cortical bone lesions are planned.

No significant financial relationships to disclose.

A phase I study of oxaliplatin (OXA) and irinotecan (IRN) in pediatric patients with refractory solid tumors: A Children's Oncology Group study

9546

Background: Platinum analogues in combination with topoisomerase 1 inhibitors have been shown in in vitro studies to have synergistic anti-tumor activity. This study estimated the maximum tolerated dose (MTD) of OXA in combination with a protracted schedule of IRN in children with refractory solid tumors. Methods: OXA was administered over 2 hrs on days 1 and 8 in combination with IRN iv over 1 hr on days 1–5 and 8–12 of a 21-day cycle. An oral cephalosporin was administered daily to ameliorate IRN-associated diarrhea. Pharmacokinetic studies of OXA and UGT1A1 genotyping were performed during course 1 in consenting patients. Results: 13 patients (median age 16 yrs, 4 M) were enrolled. Dose-limiting diarrhea (n=3), serum lipase elevation (n=3), serum amylase elevation (n=2), colitis (n=1), abdominal pain (n=1) and headache (n=1) occurred at the 1st dose level (60 mg/m2/dose OXA; 20 mg/m2/dose of IRN) in the first 3 patients. Only 1/7 patients treated with reduced doses of both agents (40 mg/m2/dose OXA; 15 mg/m2/dose IRN) experienced DLT, diarrhea. When the OXA dose (60 mg/m2) was increased with the reduced IRN dose (15 mg/m2) 2/3 patients had DLT (1 diarrhea, 1 hypokalemia). Myelosuppression was minimal at all dose levels. One patient with alveolar rhabdomyosarcoma previously treated with irinotecan (dose level 2: 40 mg/m2/dose OXA; 15 mg/m2/dose IRN) had an unconfirmed complete response of her breast metastases and one patient with refractory neuroblastoma had disease stabilization through 6 courses of therapy. The frequency of 6/6, 6/7, and 7/7 UGT1A1 promoter genotypes were 5/10, 4/10, and 1/10, respectively. Conclusions: The MTD using this schedule with oral cephalosporin support was oxaliplatin 40 mg/m2/dose with irinotecan 15 mg/m2/dose. There was some evidence of benefit but significant toxicity, both expected (diarrhea) and unexpected (elevation in pancreatic enzymes), was also observed.

[Table: see text]

In vitro evaluation of the PARP inhibitor ABT-888 in combination with temozolomide for the treatment of pediatric leukemia

9528

Background: The alkylating agent temozolomide exerts its primary cytotoxic activity through the addition to O6 methyl adducts to guanine residues in DNA, and temozolomide resistance results either from increased expression of methyl-guanine DNA methyltransferase (MGMT), which removes O6 adducts, or from mutations in the mismatch repair system (MRS), which lead to microsatellite instability (MSI). Temozolomide also creates N3 and N7 methyl adducts that are efficiently removed by the base excision repair (BER) system. PARP inhibitors block BER and may potentiate the cytotoxic effects of temozolomide. Methods: The cytotoxicity of temozolomide in combination with the PARP inhibitor ABT-888 was evaluated in vitro in leukemia cell lines and primary leukemia cells using the MTT assay. PARP activity was measured using a commercially available PARP assay. Results: ABT-888 effectively enhanced temozolomide cytotoxicity in cell lines with elevated MGMT (Jurkat and HSB2 T-cell ALL cell lines) or MRS deficiencies (Jurkat and Molt-4 T cell ALL). The temozolomide IC50 decreased from 450 μM to 35 μM at an ABT-888 concentration of 5 μM in the Jurkat T-cell ALL cell line and from 340 μM to 7.5 μM in the HSB2 T-cell line. ABT-888 also enhanced temozolomide cytotoxicity in non-T-cell leukemia subtypes, decreasing the IC50 in the JM1 pre-B ALL cell line from 51 μM to 7.7 μM and decreasing the IC50 from 316 μM to 22 μM in tumor cells obtained from a patient with pre-B ALL. PARP activity was also examined. In contrast, the sensitivity of U937 AML cells to temozolomide showed no effect of the addition of a PARP inhibitor. These results are consistent with the findings that these cells have low or undetectable MGMT and no MSI to suggest MRS mutations. Conclusion: These results suggest that ABT-888 may enhance the cytotoxic activity of temozolomide in leukemia patients whose tumors are resistant to temozolomide because of elevated MGMT expression and mismatch repair defects.

No significant financial relationships to disclose.

Phase I study of oral irinotecan, temozolomide, and vincristine for children with refractory solid tumors: A Children's Oncology Group study

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.

Chemoimmunotherapy reinduction with epratuzumab in children with ALL with marrow relapse: A Children's Oncology Group (COG) pilot study (ADVL04P2)

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]

Differential expression of survivin splice isoforms in medulloblastomas

Survivin, a member of the inhibitor of apoptosis protein family, is implicated in the dysregulation of apoptosis in human cancers. Survivin and survivin-deltaEx3, one of its two alternatively spliced isoforms, confer anti-apoptotic activities in human tumours, while survivin-2B antagonizes such anti-apoptotic properties. The current study was undertaken to examine the mRNA expression of survivin isoforms and their correlation with clinical staging and outcome in 20 medulloblastoma (MB) tumours, three MB cell lines and normal brain tissues (a foetal and an adult cerebellum) by densitometry scanning of 32p-dCTP incorporated reverse transcription polymerase chain reaction (RT-PCR) products and quantitative real-time PCR. Our results showed that the normal adult brain only expressed low levels of survivin-deltaEx3 mRNA, while the foetal brain expressed all three isoforms, with wild-type survivin as the dominant transcript. All three survivin isoforms were detected in all the MB cell lines and tumours analysed. Immunohistochemical staining also demonstrated survivin protein expressions in all five paraffin-embedded MBs, with predominant nuclear localization. Although overexpressions of survivin were not associated with the presence of metastatic MB or tumour histological subtypes, elevated expressions of survivin-deltaEx3 were significantly associated with progressive/recurrent tumours (P-value = 0.024). Our data demonstrated that overexpression of survivin mRNA is a common feature in MBs, may contribute to their anti-apoptosis properties and clinical behaviours, and predicts a poor clinical outcome, independent of clinical staging or tumour histology.

Pediatric phase 1 study of pemetrexed: A report from the Children’s Oncology Group

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.

A phase I study of bortezomib (PS-341) in pediatric patients with relapsed or refractory leukemia: A Children’s Oncology Group study

9021

Background: Bortezomib is a 26S proteasome inhibitor that is effective as a single agent for the treatment of multiple myeloma in adults. Bortezomib at a dose of 1.2 mg/m2 is well tolerated as a single agent in pediatric patients with solid tumors. This phase 1 study examined the tolerability and efficacy of bortezomib in pediatric patients with relapsed/refractory leukemia. Methods: Cohorts of 3–6 patients received bortezomib administered twice weekly (days 1, 4, 8 and 11) for two weeks every 21 days. Pharmacokinetics and NF-κB activation status were examined in peripheral blood mononuclear cells (PBMC) at 6, 12, and 24 hours following the first dose of bortezomib, and from bone marrow leukemic cells before treatment and on days 8 and 18 of the first treatment cycle. Results: Twelve patients (4 female, 8 male) (ALL=9, AML=3), median age 11y (range 1–18y), were enrolled at the 1.3 mg/m2 (6 enrolled, 3 evaluable) or 1.7 mg/m2 (6 enrolled, 2 evaluable) dose levels. Patients not fully evaluable for toxicity experienced disease progression prior to completing the first 21-day cycle of therapy. Two DLTs occurred at the 1.7 mg/m2 dose level. One patient had altered mental status and the other patient had febrile neutropenia associated with Grade 3 hypotension, Grade 4 renal insufficiency and hypoxia, followed by death on day 9 of cycle 1. No CRs or PRs were observed in the 10 patients evaluable for response. One patient had SD for 2 cycles. PK analysis (n= 5) revealed a Cl of 0.62 L/min/m2, Vd of 13 L/m2, and a terminal T1/2 of 12.6 h. NF-κB activation was inhibited in the leukemic blasts of 2 patients examined to date. Conclusions: Bortezomib was tolerated at 1.3 mg/m2 in children with relapsed/refractory leukemia. Although bortezomib appeared to inhibit NF-κB activation, it was ineffective as a single agent for pediatric leukemia treatment.

No significant financial relationships to disclose.

A phase I study of bevacizumab in children with refractory solid tumors: A Children’s Oncology Group study

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.

A phase I study of irinotecan administered on a weekly schedule in pediatric patients

BACKGROUND

The objectives of this study were to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), pharmacokinetics, and anti-tumor effect of irinotecan in pediatric patients with recurrent or refractory malignancies.

PROCEDURE

Twenty-three patients between 1 and 21 years of age, with a solid tumor refractory to standard therapy or for which there was no standard therapy were enrolled. Irinotecan was administered over 90 min weekly 4x, every 6 weeks. The initial dose level was 125 mg/m(2)/day, with subsequent escalations to 160 and 200 mg/m(2)/day. A MTD was defined in heavily-pretreated and less-heavily-pretreated (< or =2 prior chemotherapy regimens, no prior bone marrow transplantation, and no central axis radiation) patients. Pharmacokinetic studies were also performed.

RESULTS

Neutropenia and diarrhea were the DLTs in heavily pretreated patients; the MTD was 125 mg/m(2)/day. Neutropenia was the DLT in less-heavily pretreated; the MTD was 160 mg/m(2)/day. Five patients had stable disease for two to four cycles including one patient each with rhabdomyosarcoma, Ewing sarcoma, neuroblastoma, and two patients with ependymoma. Irinotecan clearance was greater that that previously reported for children receiving high dose irinotecan.

CONCLUSIONS

The recommended phase II dose of irinotecan administered weekly 4x, every 6 weeks in children with solid tumors is 125 mg/m(2)/dose for heavily pretreated patients and 160 mg/m(2)/dose for less heavily pretreated patients.

Phase I trial of intrathecal liposomal cytarabine in children with neoplastic meningitis

PURPOSE

We performed a phase I trial of intrathecal (IT) liposomal cytarabine (DepoCyt; Enzon Pharmaceuticals, Piscataway, NJ and SkyePharma Inc, San Diego, CA) to determine the maximum-tolerated dose, the dose-limiting toxicities, and the plasma and CSF pharmacokinetics of IT lipsomal cytarabine in children >/= 3 years of age with advanced meningeal malignancies.

PATIENTS AND METHODS

Eighteen assessable patients received IT liposomal cytarabine through either an indwelling ventricular access device or via lumbar puncture. Liposomal cytarabine was given once every 2 weeks during induction, once every 4 weeks during consolidation, and once every 8 weeks during the maintenance phase of treatment. The initial dose was 25 mg, with subsequent escalations to 35 and 50 mg. CSF pharmacokinetic samples were obtained in a subset of patients.

RESULTS

Arachnoiditis, characterized by fever, headache, nausea, vomiting, and back pain was noted in the first two patients at the 25 mg dose level. Therefore, subsequent patients were treated with dexamethasone, beginning the day of liposomal cytarabine administration and continuing for 5 days. Headache (grade 3) was dose limiting in two of eight patients enrolled at the 50 mg dose level. Eight of the 14 patients assessable for response demonstrated evidence of benefit manifest as prolonged disease stabilization or response.

CONCLUSION

The maximum-tolerated dose and recommended phase II dose of liposomal cytarabine in patients between the ages of 3 and 21 years is 35 mg, administered with dexamethasone (0.15 mg/kg/dose, twice a day for 5 days). A phase II trial of IT liposomal cytarabine in children with CNS leukemia in second or higher relapse is in development.

Pediatric phase I trial and pharmacokinetic study of the platelet-derived growth factor (PDGF) receptor pathway inhibitor SU101

PURPOSE

To determine the maximum tolerated dose and the toxicity profile of the PDGF receptor pathway inhibitor SU101 in pediatric patients with refractory solid tumors, and to define the plasma pharmacokinetics of SU101 and its active metabolite SU0020 in children.

EXPERIMENTAL DESIGN

Patients between 3 and 21 years of age with CNS malignancy, neuroblastoma, or sarcoma refractory to standard therapy were eligible. The starting dose of SU101 was 230 mg/m(2) per day administered as a 96-h continuous infusion every 21 days. Blood for pharmacokinetic analysis was obtained during the first cycle.

RESULTS

Entered into the trial were 27 patients, and 24 were fully evaluable for toxicity. Dose-limiting central nervous system toxicity was observed in two patients at the 440 mg/m(2) per day dose level. Non-dose-limiting toxicities included nausea, vomiting, headache, fatigue, abdominal discomfort, diarrhea, pruritus, anorexia, constipation, and paresthesias. There were no complete or partial responses. One patient with rapidly progressive desmoplastic small round-cell tumor experienced symptomatic improvement and prolonged stable disease. Steady-state concentrations of SU101 were rapidly achieved and proportional to dose. The concentration of SU0020 was 100- to 1000-fold greater than that of SU101. The median clearance of SU0020 was 0.19 l/day per m(2) and its terminal elimination half-life was 14 days.

CONCLUSIONS

SU101 administered on this schedule was generally well tolerated. The maximum tolerated dose of SU101 is 390 mg/m(2) per day for 4 days repeated every 3 weeks. The neurotoxicity observed at the 440 mg/m(2) per day dose level suggests that patients receiving repetitive cycles must be monitored closely, as SU0020 may accumulate over time.

The development of camptothecin analogs in childhood cancers

Camptothecin analogs, agents that target the intranuclear enzyme topoisomerase I, represent a promising new class of anticancer drugs for the treatment of childhood cancer. In preclinical studies, camptothecins, such as topotecan and irinotecan, are highly active against a variety of pediatric malignancies including neuroblastomas, rhabdomyosarcomas, gliomas, and medulloblastomas. In this paper, we review the status of completed and ongoing clinical trials and pharmacokinetic studies of camptothecin analogs in children. These and future planned studies of this novel class of cytotoxic agents are critical to defining the ultimate role of topoisomerase I poisons in the treatment of childhood cancer.

Treatment controversies in medulloblastoma

Medulloblastoma, the most common primary malignant brain tumor in children, is a radiosensitive and chemosensitive tumor. Nevertheless, medulloblastoma remains a management challenge for the clinical oncologist, because the optimal sequence and dosage for each treatment modality has not yet been defined. In addition, effective management strategies for medulloblastoma may result in profound neuroendocrine and neuropsychologic sequelae. In this article, we review the clinical and biologic prognostic factors for classifying medulloblastoma, current strategies for the management of this disease, and potential strategies to prevent or minimize long-term treatment sequelae.

Intrathecal chemotherapy

An unforeseen consequence of improved disease-free survival in many hematologic and solid tumor malignancies has been an increase in the incidence of disease recurrence in the leptomeninges. The recognition of the central nervous system (CNS) as a unique 'sanctuary' site has resulted in the development of therapeutic strategies specifically directed at the leptomeninges. Although therapeutic strategies have been successful in the prevention and treatment of CNS leukemia, there are still a paucity of therapeutic options for patients with neoplastic meningitis due to solid tumors or recurrent CNS leukemia. This article provides an overview of the pharmacology and toxicity of intrathecal agents that are commonly employed in the treatment and prevention of leptomeningeal disease, and describes new agents that are in the early stages of clinical development.

Recombinant urate oxidase for the prophylaxis or treatment of hyperuricemia in patients With leukemia or lymphoma

PURPOSE

To improve the control of hyperuricemia in patients with leukemia or lymphoma, we tested a newly developed uricolytic agent, recombinant urate oxidase (SR29142; Rasburicase; Sanofi-Synthelabo, Inc, Paris, France), which catalyzes the oxidation of uric acid to allantoin, a highly water-soluble metabolite readily excreted by the kidneys.

PATIENTS AND METHODS

We administered Rasburicase intravenously, at 0.15 or 0.20 mg/kg, for 5 to 7 consecutive days to 131 children, adolescents, and young adults with newly diagnosed leukemia or lymphoma, who either presented with abnormally high plasma uric acid concentrations or had large tumor cell burdens. Blood levels of uric acid, creatinine, phosphorus, and potassium were measured daily. The pharmacokinetics of Rasburicase, the urinary excretion rate of allantoin, and antibodies to Rasburicase were also studied.

RESULTS

At either dosage, the recombinant enzyme produced a rapid and sharp decrease in plasma uric acid concentrations in all patients. The median level decreased by 4 hours after treatment, from 9.7 to 1 mg/dL (P =.0001), in the 65 patients who presented with hyperuricemia, and from 4.3 to 0.5 mg/dL (P =.0001) in the remaining 66 patients. Despite cytoreductive chemotherapy, plasma uric acid concentrations remained low throughout the treatment (daily median level, 0.5 mg/dL). The urinary excretion rate of allantoin increased during Rasburicase treatment, peaking on day 3. Serum phosphorus concentrations did not change significantly during the first 3 days of treatment, decreased significantly by day 4 in patients presenting with hyperuricemia (P =.0003), and fell within the normal range in all patients by 48 hours after treatment. Serum creatinine levels decreased significantly after 1 day of treatment in patients with or without hyperuricemia at diagnosis (P =.0003 and P =.02, respectively) and returned to normal range in all patients by day 6 of treatment. Toxicity was negligible, and none of the patients required dialysis. The mean plasma half-lives of the agent were 16.0 +/- 6.3 (SD) hours and 21.1 +/- 12.0 hours, respectively, in patients treated at dosages of 0.15 or 0.20 mg/kg. Seventeen of the 121 assessable patients developed antibodies to the enzyme.

CONCLUSION

Rasburicase is safe and highly effective for the prophylaxis or treatment of hyperuricemia in patients with leukemia or lymphoma.

Phase II trial of pyrazoloacridine in children with solid tumors: a Pediatric Oncology Group phase II study

PURPOSE

Pyrazoloacridine (PZA), a rationally synthesized deoxyribonucleic acid (DNA) binding agent that preferentially inhibits ribonucleic acid rather than DNA synthesis, is active against hypoxic and noncycling tumor cells and has greater in vitro activity against a broad range of human solid tumor lines than against the L1210 murine leukemia line. The Pediatric Oncology Group conducted a phase II study to determine the activity of PZA administered as a 3-hour infusion.

PATIENTS AND METHODS

The activity of PZA was evaluated in patients with a variety of childhood solid tumors including rhabdomyosarcoma, Ewing sarcoma/peripheral neuroectodermal tumor, neuroblastoma, osteogenic sarcoma, Wilms tumor, or other solid tumors (excluding brain tumors). In addition to a standard three-stage design to test the drug's activity in each tumor type, a global stopping rule was used such that if no complete or partial responses (CR or PR) occurred in the first 35 patients (pooled across all strata except "other"), the study would be closed.

RESULTS

A total of 47 patients were entered into the study. Myelosuppression was the primary toxicity. Severe nonhematologic toxicity was uncommon. Only one patient exhibited grade 3 neurologic toxicity (anxiety). No CRs or PRs were observed.

CONCLUSION

Use of the global stopping criterion permitted early identification of lack of activity of PZA against childhood solid tumors.

Modified procedure for implantation of subcutaneous central venous access devices in macaques (Macaca mulatta)

A nonhuman primate model comprising adult male rhesus monkeys (Macaca mulatta) with chronically indwelling subcutaneous central venous access devices provides a unique opportunity to determine plasma pharmacokinetics of new drugs such as anticancer and anti- retroviral agents. The central venous access we use is a low-profile, single-septum, titanium port that is attached to a radiopaque, indwelling catheter; the catheter is implanted in an internal jugular vein. A common complication following placement of the venous access device was migration of the catheter tip. We therefore modified the standard procedure by cutting the silicone catheter and introducing the rigid connector to secure the catheter to the vessel at the insertion site (approximately 9 to 13 cm from the distal end of the catheter). Prior to the use of the connector, three of five catheters migrated within 4 weeks after placement. In contrast, all 13 internal jugular catheters with connectors have remained patent without migration of the catheter tip. Therefore, incorporation of the catheter connector appears to have eliminated the problem of catheter migration.

Clinical pharmacology of encapsulated sustained-release cytarabine

BACKGROUND

The therapeutic effectiveness of chemotherapy is often limited by the inability to sustain cytotoxic concentrations at the tumor site. Cytarabine liposome injection (DepoCyt), a sterile, injectable suspension of the antimetabolite cytarabine, encapsulated into multivesicular, lipid-based particles, has been developed to improve the treatment of neoplastic meningitis (NM) through sustained release of cytarabine.

OBJECTIVE

To review the pharmacokinetics, efficacy, and safety of intrathecal DepoCyt for the treatment of NM secondary to lymphoma or solid tumors.

RESULTS

In preclinical and clinical studies, DepoCyt markedly extended the duration of tumor exposure to cytotoxic concentrations of cytarabine compared with administration of unbound cytarabine. Data from recent clinical studies demonstrate that DepoCyt improves complete response rates among patients with NM secondary to lymphoma. Trends in time to neurologic progression and median survival also favored DepoCyt over unbound cytarabine in these studies. Data have also been presented that suggest that patients with NM secondary to solid tumors benefit more from DepoCyt than from conventional treatment approaches. Chemical arachnoiditis (i.e., headache, fever, nausea, vomiting) was common in patients receiving DepoCyt, however, symptoms were manageable with oral dexamethasone.

CONCLUSIONS

Encapsulation of cytarabine into liposomes for sustained release prolongs tumor exposure to cytotoxic concentrations of cytarabine, which may improve therapeutic efficacy in patients with NM secondary to lymphoma or solid tumors.

Neoplastic meningitis: diagnosis and treatment considerations

Neoplastic meningitis is an increasingly recognized complication of advanced metastatic cancer and, if left undiagnosed or untreated, is characterized by rapid neurologic deterioration and death. Thus, the diagnosis and treatment of neoplastic meningitis present challenges for the clinical oncologist. The diagnosis of neoplastic meningitis is based on clinical signs and symptoms, laboratory analysis of cerebrospinal fluid to determine cell count and cytology, and analysis of neuroimaging studies for evidence of leptomeningeal or cranial nerve enhancement. Once diagnosed, conventional treatment regimens may include radiotherapy combined with systemic or intrathecal chemotherapy, often with the antimetabolites cytarabine and/or methotrexate. However, the prognosis for neoplastic meningitis secondary to an underlying solid tumor or recurrent leukemia is poor with conventional treatment regimens. Therefore, novel agents for intrathecal administration, including DepoCyttrade mark, mafosfamide, and topotecan, or novel therapeutic approaches, including conjugated monoclonal antibodies and immunotoxins or gene therapy, are currently under investigation. Such new agents and therapeutic approaches will facilitate the development of effective treatment strategies and will ultimately improve the outcome for patients with this devastating disease. This article provides an overview of the approaches to the diagnosis, evaluation, and treatment of neoplastic meningitis.

Methotrexate distribution within the subarachnoid space after intraventricular and intravenous administration

PURPOSE

Intrathecal methotrexate achieves high concentrations in cerebrospinal fluid (CSF), but drug distribution throughout the subarachnoid space after an intralumbar dose is limited. The objective of this study was to quantify methotrexate distribution in CSF after intraventricular and intravenous administration and to identify factors that influence CSF distribution.

METHODS

Nonhuman primates (Macaca mulatta) with permanently implanted catheters in the lateral and fourth ventricles received methotrexate by bolus injection (0.5 mg) and infusion (0.05 to 0.5 mg/day over 24 to 168 h) into the lateral ventricle, as well as intravenous infusions. CSF was sampled from the lumbar space, fourth ventricle and the subarachnoid space at the vertex. Methotrexate in CSF and plasma was measured with the dihydrofolate reductase inhibition assay.

RESULTS

After bolus intraventricular injection, methotrexate exposure in lumbar CSF ranged from 11% to 69% of that achieved in the fourth ventricle. During continuous intraventricular infusions, methotrexate steady-state concentrations (C(ss)) in lumbar CSF and CSF from the vertex were only 20% to 25% of the ventricular CSF C(ss). The dose, duration of infusion, and infusate volume did not influence drug distribution to the lumbar CSF, but probenicid increased the lumbar to ventricular C(ss) ratio, suggesting the involvement of a probenicid-sensitive transport pump in the efflux of MTX from the CSF. During the intravenous infusions, the ventricular methotrexate C(ss) was lower than the lumbar C(ss) and the C(ss) in CSF from the vertex.

CONCLUSION

Methotrexate CSF distribution after intraventricular injection was uneven, and at steady-state CSF methotrexate concentrations were lower at sites that were more distant from the injection site.

Pharmacokinetics and cerebrospinal fluid penetration of CI-994 (N-acetyldinaline) in the nonhuman primate

CI-994 is a substituted benzamide derivative that has demonstrated significant antitumor activity in vitro and in vivo against a broad spectrum of murine and human tumor models. Its mechanism of action is still unknown but seems to be novel compared with existing anticancer drugs. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of CI-994 in nonhuman primates. Three animals (total 4 doses) received an 80 mg/m2 dose of CI-994 administered over 20 min, and one animal received a dose of 100 mg/m2. Serial plasma and fourth ventricular CSF samples were obtained from 0 to 4320 min after administration of the 80-mg/m2 dose, and only plasma samples were obtained after the 100-mg/m2 dose. CI-994 was measured using a previously validated reverse-phase high-performance liquid chromatography assay. Elimination of CI-994 from plasma was triexponential (4 of 5 cases) or biexponential (1 of 5 cases), with a terminal half life (t1/2) of 7.4 +/- 2.5 h, volume of distribution of 15.5 +/- 1.8 L/m2, and clearance of 40 +/- 6 ml/min/m2. The area under the concentration-time curve (AUC) for the 80-mg/m2 dose was 125 +/- 17 microM x hr. CI-994 was first detected in CSF at the completion of the i.v. infusion. Peak concentrations of CI-994 in CSF were 3.4 +/- 0.3 microM. Elimination from CSF was monoexponential (2 of 4 cases) or biexponential (2 of 4 cases) with a terminal t1/2 in CSF of 12.9 +/- 2.5 h and AUC of 55 +/- 18 microM x hr. The AUC(CSF):AUCplasma ratio was 43 +/- 10%. This study demonstrates that there is excellent CSF penetration of CI-994 after i.v. administration. Additional studies are needed to evaluate the potential role of CI-994 in the treatment of central nervous system neoplasms.

Thioguanine administered as a continuous intravenous infusion to pediatric patients is metabolized to the novel metabolite 8-hydroxy-thioguanine

Thiopurine antimetabolites have been in clinical use for more than 40 years, yet the metabolism of thiopurines remains only partially understood. Data from our previous pediatric phase 1 trial of continuous i.v. infusion of thioguanine (CIVI-TG) suggested that TG was eliminated by saturable mechanism, with conversion of the drug to an unknown metabolite. In this study we have identified this metabolite as 8-hydroxy-thioguanine (8-OH-TG). The metabolite coeluted with the 8-OH-TG standard on HPLC and had an identical UV spectrum, with a lambda(max) of 350 nm. On mass spectroscopy, the positive ion, single quad scan of 8-OH-TG yielded a protonated molecular ion at 184 Da and contained diagnostic ions at m/z 167, 156, 142, and 125 Da. Incubation of TG in vitro with partially purified aldehyde oxidase resulted in 8-OH-TG formation. 8-OH-TG is the predominant circulating metabolite found in patients receiving CIVI-TG and is likely generated by the action of aldehyde oxidase.

Phase I trial of docetaxel with filgrastim support in pediatric patients with refractory solid tumors: a collaborative Pediatric Oncology Branch, National Cancer Institute and Children's Cancer Group trial

Neutropenia is the dose-limiting toxicity of docetaxel in children. This Phase I trial was designed to determine the maximum tolerated dose, the dose-limiting toxicities, and the incidence and severity of other toxicities of docetaxel with filgrastim (G-CSF) support in children with refractory solid tumors. Docetaxel was administered as an i.v. infusion for 1 h every 21 days with a starting dose of 150 mg/m2 and an escalation to 185 mg/m2 and 235 mg/m2 in subsequent patient cohorts. G-CSF (5 microg/kg/day) was administered s.c., starting 48 h after docetaxel and continuing until the post-nadir neutrophil count reached 10,000/microl. Seventeen patients received 27 courses of docetaxel with G-CSF support. Generalized erythematous desquamating skin rash and myalgias were dose-limiting at 235 mg/m2. Localized and generalized rashes were seen at all of the three dose levels. Neutropenia (median nadir, 95/1microl) occurred at all of the dose levels but was brief in duration and not dose-limiting. Thrombocytopenia was minimal (median platelet count nadir, 139,000/microl), and the severity of neutropenia and thrombocytopenia did not seem to be related to the docetaxel dose. Other docetaxel-related toxicities included hemorrhage (associated with mucositis), sepsis, hypersensitivity reaction, transient elevation of liver enzymes, stomatitis, back pain, asthenia, and neuropathy. One minor response was observed in a patient with colon cancer. The maximum tolerated dose of docetaxel with G-CSF support in children is 185 mg/m2, which is 50% higher than the maximum tolerated dose of docetaxel alone in children and 85 % higher than the recommended adult dose.

Plasma and CSF pharmacokinetics of ganciclovir in nonhuman primates

PURPOSE

The antiviral nucleoside analogue ganciclovir is a potent inhibitor of replication in herpes viruses and is effective against cytomegalovirus infections in immunocompromised patients. Ganciclovir is also used in cancer gene therapy studies that utilize the herpes simplex virus thymidine kinase gene (HSV-TK). The pharmacokinetics of ganciclovir in adults and children have been described previously but there are no detailed studies of the CNS pharmacology of ganciclovir. We studied the pharmacokinetics of ganciclovir in plasma and CSF in a nonhuman primate model that is highly predictive of the CSF penetration of drugs in humans.

METHODS

Ganciclovir, 10 mg/kg i.v., was administered over 30 min to three animals. Ganciclovir concentrations in plasma and CSF were measured using reverse-phase HPLC.

RESULTS

Peak plasma ganciclovir concentrations ranged from 18.3 to 20.0 microg/ml and the mean plasma AUC was 1075+/-202 microg/ml x min. Disappearance of ganciclovir from the plasma was biexponential with a distribution half-life (t(1/2)alpha) of 18+/-7 min and an elimination half-life (t(1/2)beta) of 109+/-7 min. Total body clearance (ClTB) was 9.4+/-1.6 ml/min/kg. The mean CSF ganciclovir AUC was 168+/-83 microg/ml x min and the mean peak CSF concentration was 0.7+/-0.3 microg/ml. The ratio of the AUCs in CSF and plasma was 15.5+/-7.1%.

CONCLUSIONS

Ganciclovir penetrates into the CSF following i.v. administration. This finding will be useful in the design of gene therapy trials involving the HSV-TK gene followed by treatment with ganciclovir in CNS or leptomeningeal tumors.

Plasma and cerebrospinal fluid pharmacokinetics of 9-aminocamptothecin (9-AC), irinotecan (CPT-11), and SN-38 in nonhuman primates

PURPOSE

The plasma and cerebrospinal fluid (CSF) pharmacokinetics of the camptothecin analogs, 9-aminocamptothecin (9-AC) and irinotecan, were studied in a nonhuman primate model to determine their CSF penetration.

METHODS

9-AC, 0.2 mg/kg (4 mg/m2) or 0.5 mg/kg (10 mg/m2), was infused intravenously over 15 min and irinotecan, 4.8 mg/kg (96 mg/m2) or 11.6 mg/kg (225 mg/m2), was infused over 30 min. Plasma and CSF samples were obtained at frequent intervals over 24 h. Lactone and total drug forms of 9-AC, irinotecan, and the active metabolite of irinotecan, SN-38, were quantified by reverse-phase HPLC.

RESULTS

9-AC lactone had a clearance (CL) of 2.1 +/- 0.9 l/kg per h, a volume of distribution at steady state (Vd[ss]) of 1.6 +/- 0.7 l/kg and a half-life (t1/2) of 3.2 +/- 0.8 h. The lactone form of 9-AC accounted for 26 +/- 7% of the total drug in plasma. The CSF penetration of 9-AC lactone was limited. CSF 9-AC lactone concentration peaked 30 to 45 min after the dose at 11 to 21 nM (0.5 mg/kg dose), and the ratio of the areas under the CSF and plasma concentration-time curves (AUC(CSF):AUC[P]) was only 3.5 +/- 2.1%. For irinotecan, the CL was 3.4 +/- 0.4 l/kg per h, the Vd(ss) was 7.1 +/- 1.3 l/kg, and the t1/2 was 4.9 +/- 2.2 h. Plasma AUCs of the lactone form of SN-38 were only 2.0% to 2.4% of the AUCs of irinotecan lactone. The lactone form of irinotecan accounted for 26 +/- 5% of the total drug in plasma, and the lactone form of SN-38 accounted for 55 +/- 6% of the total SN-38 in plasma. The AUC(CSF):AUC(P) ratio for irinotecan lactone was 14 +/- 3%. SN-38 lactone and carboxylate could not be measured (< 1.0 nM) in CSF. The AUC(CSF):AUC(P) ratio for SN-38 lactone was estimated to be < or = 8%.

CONCLUSION

Despite their structural similarity, the CSF penetration of 9-AC and SN-38 is substantially less than that of topotecan which we previously found to have an AUC(CSF):AUC(P) ratio of 32%.

Phase II trial of topotecan administered as 72-hour continuous infusion in children with refractory solid tumors: a collaborative Pediatric Branch, National Cancer Institute, and Children's Cancer Group Study

The antitumor activity of topotecan administered as a 72-h continuous i.v. infusion was evaluated in children with refractory neuroblastoma and sarcomas of soft tissue and bone. We also attempted to increase the dose intensity of topotecan by including an intrapatient dose escalation in the trial design. Ninety-three children (85 eligible and evaluable for response) with recurrent or refractory neuroblastoma, osteosarcoma, Ewing's sarcoma/peripheral neuroectodermal tumor, rhabdomyosarcoma, or other soft-tissue sarcomas received topotecan administered as a 72-h i.v. infusion every 21 days. The initial dose was 1.0 mg/m2/day, with subsequent intrapatient dose escalation to 1.3 mg/m2/day for those patients who did not experience dose-limiting toxicity after their first cycle of topotecan. There was one complete response in a patient with neuroblastoma (n = 26) and one partial response in a patient with Ewing's sarcoma/peripheral neuroectodermal tumor (n = 25). No complete or partial responses were observed in 17 patients with osteosarcoma, 15 patients with rhabdomyosarcoma, or 2 patients with other soft-tissue sarcomas; however, 8 patients had prolonged (15-48 weeks) stable disease while receiving topotecan. Topotecan was well tolerated. The most commonly observed toxicities were myelosuppression (dose-limiting) and nausea and vomiting. Intrapatient dose escalations were performed in 68% of the patients who received more than one cycle of topotecan, and 1.3 mg/m2/day was tolerated by 79% of the patients who received the higher dose and were evaluable for hematological toxicity. In conclusion, topotecan administered as a 72-h continuous infusion every 21 days is inactive (objective response rate, < 20%) in children with refractory or recurrent neuroblastoma and sarcomas of soft tissue or bone.

Phase I trial and pharmacokinetic study of pyrazoloacridine in children and young adults with refractory cancers

PURPOSE

To define the maximum-tolerated dose (MTD), quantitative and qualitative toxicities, recommended phase II dose, and pharmacokinetics of pyrazoloacridine (PZA) administered as a 1- or 24-hour infusion in children and young adults with refractory cancers.

PATIENTS AND METHODS

Twenty-two patients received PZA as a 1-hour infusion at doses of 380 mg/m2 (n = 3), 495 mg/m2 (n = 6), 640 mg/m2 (n = 6), and 835 mg/m2 (n = 7). An additional four patients received PZA as a 24-hour infusion at the MTD (640 mg/m2) for the 1-hour infusion schedule. Plasma samples were obtained for pharmacokinetic analysis in 17 patients. PZA concentration in plasma was measured by reverse-phase high-performance liquid chromatography (HPLC). A two-compartment pharmacokinetic model was fit to the PZA plasma concentration data.

RESULTS

On the 1-hour infusion schedule, dose-limiting myelosuppression (neutropenia more than thrombocytopenia) was observed in two of seven patients at the 835-mg/m2 dose level. Myelosuppression did not appear to be ameliorated by prolonging the infusion to 24 hours. Nonhematologic toxicities were minor. Significant neurotoxicity, which was dose-limiting in adults treated with a 1-hour infusion of PZA, was observed in one patient treated at 640 mg/m2, but was not dose-limiting. There was marked interpatient variability in plasma PZA concentrations at all dose levels. The pharmacokinetic profile of PZA was characterized by an initial rapid decline (alpha half-life [t(1/2)alpha], 0.5 hours) followed by a prolonged elimination phase (t(1/2)beta, 30 hours). The volume of distribution at steady-state (Vd(ss)) was 700 L/m2 and the clearance was 300 mL/min/m2. There was no evidence of dose-dependent clearance. The area under the PZA concentration-time curve (AUC) correlated poorly with dose and was more predictive of the degree of myelosuppression than was PZA dose.

CONCLUSION

PZA administered as 1- or 24-hour infusion is well tolerated by children and young adults. The dose-limiting toxicity (DLT) is myelosuppression. Neurotoxicity is not prominent in this age group. There was marked interpatient variation in plasma concentrations of PZA. The recommended dose for phase II studies is 640 mg/m2.

Phase I trial and pharmacokinetic study of all-trans-retinoic acid administered on an intermittent schedule in combination with interferon-alpha2a in pediatric patients with refractory cancer

PURPOSE

To determine the maximum-tolerated dose (MTD) of all-trans-retinoic acid (ATRA) administered on an intermittent oral schedule with interferon-alpha2a (IFN-alpha2a) in children with refractory cancer, and whether the marked reduction in plasma ATRA concentrations observed with chronic daily oral dosing could be circumvented with an intermittent dosing schedule.

PATIENTS AND METHODS

Thirty-three children with refractory cancer (stratified by age, < or = 12 and > 12 years) were treated with ATRA 3 consecutive days per week and IFN-alpha2a 3 x 10(6) U/m2 5 consecutive days per week, both repeated weekly. The starting dose of ATRA was 60 mg/m2/d divided into three doses, with planned escalations to 90 and 120 mg/m2/d. Because severe headaches have been noted to occur on the initial day of ATRA administration, only two of three doses of ATRA were administered on day 1 of each week.

RESULTS

Pseudotumor cerebri or dose-limiting headache was observed in two of five patients older than 12 years treated at the 120-mg/m2/d dose level and in one of six < or = 12 years at the 90-mg/m2/d level. Other non-dose-limiting toxicities of ATRA included reversible elevations in hepatic transaminases and triglycerides, dry skin, cheilitis, and nausea/vomiting. One child with recurrent neuroblastoma had an objective response of 6 months' duration, and one with recurrent Wilms' tumor had histologic maturation of multiple tumors. This intermittent schedule allowed for exposure to relatively high plasma concentrations of ATRA on a repetitive basis. Following 30-mg/m2 doses, the ATRA area under the concentration-time curve (AUC) decreased from 96 +/- 14 micromol/L/min on day 1 to 26 +/- 24 micromol/L/min by day 3 of drug administration, but on day 1 of the fourth consecutive week of therapy, the AUC averaged 110 +/- 16 micromol/L/min. The recommended pediatric phase II dose of ATRA administered on this schedule is 90 mg/m2/d.

CONCLUSION

An intermittent schedule of ATRA administration appears to circumvent the low plasma drug exposure that is a result of the sustained upregulation of metabolism when this drug is administered on a chronic daily schedule. Based on the results of this trial, a phase II trial of ATRA/IFN-alpha2a in neuroblastoma and Wilms' tumor using this schedule is in progress.

Phase I trial of docetaxel administered as a 1-hour infusion in children with refractory solid tumors: a collaborative pediatric branch, National Cancer Institute and Children's Cancer Group trial

PURPOSE

A phase I trial of docetaxel was performed to determine the maximum-tolerated dose (MTD), the dose-limiting toxicities, and the incidence and severity of other toxicities in children with refractory solid tumors.

PATIENTS AND METHODS

Forty-four children received 103 courses of docetaxel administered as a 1-hour intravenous infusion every 21 days. Doses ranged from 55 to 150 mg/m2, MTD was defined in heavily pretreated and less heavily pretreated (< or = 2 prior chemotherapy regimens, no prior bone marrow transplantation [BMT], and no radiation to the spine, skull, ribs, or pelvic bones) patients.

RESULTS

Dose-related neutropenia was the primary dose-limiting toxicity. The MTD in the heavily pretreated patient group was 65 mg/m2, but the less heavily pretreated patients tolerated a significantly higher dose of docetaxel (maximum-tolerated dose, 125 mg/m2). Neutropenia and constitutional symptoms consisting of malaise, myalgias, and anorexia were the dose-limiting toxicities at 150 mg/m2 in the less heavily pretreated patients. Thrombocytopenia was not prominent, even in patients who experienced dose-limiting neutropenia. Common nonhematologic toxicities of docetaxel included skin rashes, mucositis, and mild elevations of serum transaminases. Neuropathy was uncommon. Peripheral edema and weight gain were observed in two of five patients who received more than three cycles of docetaxel. A complete response (CR) was observed in one patient with rhabdomyosarcoma, a partial response (PR) in one patient with peripheral primitive neuroectodermal tumor (PPNET), and a minimal response (MR) in two patients with PPNET. Three of the four responding patients were treated at doses > or = 100 mg/m2.

CONCLUSION

The recommended phase II dose of docetaxel administered as a 1-hour intravenous infusion in children with solid tumors in 125 mg/m2. Because neutropenia was the dose-limiting toxicity and thrombocytopenia was mild, further escalation of the dose should be attempted with granulocyte colony-stimulating factor (G-CSF) support.

Phase II evaluation of topotecan for pediatric central nervous system tumors

BACKGROUND

Topotecan is a topoisomerase I inhibitor that has good penetration across the blood-brain barrier and significant antitumor activity against human brain tumor xenografts. In a Phase I trial in children with refractory cancer, topotecan was well tolerated when administered as a 24-hour infusion. The maximum tolerated dose was 5.5 mg/m2 and the dose-limiting toxicity was myelosuppression. This Phase II study of topotecan was performed to assess the activity of topotecan against childhood brain tumors.

METHODS

Forty-five children with either a previously treated primary brain tumor that was refractory to standard therapy, or an untreated brain stem glioma or glioblastoma multiforme, received topotecan administered as a 24-hour intravenous infusion every 21 days. The initial dose was 5.5 mg/m2 with escalation to 7.5 mg/m2 on the second and subsequent doses in patients who did not experience dose-limiting toxicity.

RESULTS

There were no complete or partial responses in the patients with high grade glioma (n=9), medulloblastoma (n=9), or brain stem glioma (n=14). One of 2 patients with a low grade glioma had a partial response lasting more than 17 months; 3 patients with a brain stem glioma had stable disease for 12 to 28 weeks; and 1 patient with a malignant neuroepithelial tumor and 1 patient with an optic glioma had stable disease for 41 weeks and 22 weeks, respectively. Dose escalation from 5.5 mg/m2 to 7.5 mg/m2 was well tolerated in the first 11 patients enrolled on this study who had not received prior craniospinal radiation therapy. The starting dose was subsequently increased to 7.5 mg/m2 for patients without prior craniospinal radiation.

CONCLUSIONS

Topotecan administered as a 24-hour infusion every 21 days is inactive in high grade gliomas, medulloblastomas, and brain stem tumors.

Central nervous system leukemia

The treatment of central nervous system (CNS) leukemia still poses a significant challenge to the clinical oncologist despite significant advances in therapeutic strategies that are directly targeted at the CNS. This article reviews the evolving definition of CNS leukemia, the current status of therapy for the prevention and treatment of overt CNS leukemia, pharmacological considerations in the treatment of CNS leukemia, and the longterm sequelae of CNS-directed therapy, focusing on articles that have been published in the past 2 years. New agents and treatment strategies for the treatment and prevention of CNS leukemia are also discussed.

Pharmacologic strategies for the treatment of meningeal malignancy

There have been significant strides in the treatment and prevention of meningeal cancer, particularly meningeal leukemia, during the past thirty years. These advantages are a direct result of innovative therapeutic approaches specifically designed to overcome the limitations of systemically administered chemotherapy. Such approaches include the administration of intrathecal chemotherapy by intralumbar or intraventricular injection, the administration of very high-dose systemic chemotherapy, and the administration of cranial or craniospinal irradiation. A better understanding of the central nervous system pharmacokinetics of commonly used anticancer agents has also resulted in improvements in the treatment of meningeal cancer. In this article, the clinical pharmacology of the most commonly used intrathecal agents and pharmacologic strategies for the treatment of meningeal cancer will be discussed. In addition, an overview of new agents for intrathecal administration and other novel CNS targeted therapies will be presented.

Pharmacokinetics of lamivudine and BCH-189 in plasma and cerebrospinal fluid of nonhuman primates

2'-Deoxy-3'-thiacytidine is a dideoxycytidine analog with a sulfur in place of the 3' carbon of the ribose. There are two enantiomeric forms of the compound, both of which inhibit human immunodeficiency virus type 1 and 2 replication in vitro. However, the (-) enantiomer (lamivudine) appears to be significantly less cytotoxic to uninfected lymphocytes than is the (+) enantiomer. Lamivudine has entered initial clinical trials, and the present study was designed to describe the pharmacokinetic behavior of this compound in both plasma and cerebrospinal fluid (CSF) of primates. Lamivudine was administered as an intravenous bolus dose of 20 mg/kg for 24 h for administration. Urine samples were also obtained from two animals. The same dose of the racemate (BCH-189) was administered to one animal. The drug was quantitated in CSF and plasma with a reverse-phase high-pressure liquid chromatography technique. Elimination of lamivudine from plasma was biexponential, with a mean alpha phase half-life of 5.4 min, a mean beta phase half-life of 84 min, and a total clearance of 6.1 liters/h. The total clearance of the same dose of BCH-189 in a single animal was 11.0 liters/h. In two animals from which urine was obtained for 12 h postadministration, 32 and 59% of the drug was recovered unchanged. The deamination product of lamivudine was not detected. The CSF/plasma ratio of lamivudine was significantly higher when the drug was measured in the lumbar CSF (mean, 0.41) than when it was measured in the ventricular CSF (mean, 0.079). The measured CSF/plasma ratio for ventricular CSF is equivalent to that of other dideoxycytidine analogs, confirming the importance of the nucleobase in determining the degree of CSF penetration. The difference in lamivudine exposure in ventricular and lumbar CSF suggests that there is a transport mechanism for efflux of cytidine analogs from ventricular CSF.