Acetylcysteine, Mannitol, Combination Chemotherapy, and Sodium Thiosulfate in Treating Children With Malignant Brain Tumors

• To assess toxicity and the maximally tolerated dose of N-acetylcysteine administered in conjunction with carboplatin, cyclophosphamide and etoposide phosphate BBBD, and delayed high dose sodium thiosulfate, in children with malignant brain tumors. [ Designated as safety issue: Yes ]
  

Biological: filgrastim Drug: acetylcysteine
administered i.v. over 30 to 60 minutes
Drug: carboplatin
(200 mg/m2/day; total dose 400 mg/m2) will be infused i.a. over 10 minutes, in 50-180 cc of normal saline.
Drug: cyclophosphamide
(330 mg/m2/day; total dose 660 mg/m2) will be infused i.v. in 25-50 cc of normal saline, over approximately 10 minutes.
Drug: etoposide phosphate
(200 mg/m2/day; total dose 400 mg/m2) will be infused i.v. in 25-100 cc of normal saline, over approximately 10 minutes, immediately following the cyclophosphamide.
Drug: mannitol
(25%) delivered i.a. at a pre-determined flow rate over 30 seconds. The flow rate will be determined by iodinated contrast injection and fluoroscopy as the lowest infusion rate in which there is retrograde flow from the arterial catheter. The rate and volume of mannitol infused will be approximately 4-12 cc/sec x 30 seconds.
Drug: sodium thiosulfate
STS is available as a 25% (250 mg/ml) solution. The dose of STS administered 4 hours after carboplatin is 16 gm/m2. The dose of STS administered 8 hours after carboplatin is 16 gm/m2. Actual dose to be administered will be determined and mixed with an equivalent amount of sterile water (1 ml:1 ml) for infusion.

OBJECTIVES:

Primary

• Determine the toxicity and maximum tolerated dose of acetylcysteine when given in combination with blood-brain barrier disruption treatment with mannitol, combination chemotherapy comprising cyclophosphamide, etoposide phosphate, and carboplatin, and delayed high-dose sodium thiosulfate in pediatric patients with malignant brain tumors.

Secondary

• Determine the blood/bone marrow toxicity of this regimen in these patients.
• Determine tumor response in patients treated with this regimen.

OUTLINE: This is a dose-escalation study of acetylcysteine.

Patients receive acetylcysteine IV over 30-60 minutes followed, at least 15 minutes later, by x-ray-guided femoral artery catheterization under general anesthesia on days 1 and 2. After placement of the catheter, patients receive cyclophosphamide IV over 10 minutes, etoposide phosphate IV over 10 minutes, mannitol intra-arterially (IA) over 30 seconds, and carboplatin IA over 10 minutes also on days 1 and 2. Patients then receive high-dose sodium thiosulfate IV over 15 minutes 4 hours after completion of carboplatin. Some patients may receive a second dose of sodium thiosulfate 8 hours after completion of carboplatin. Beginning 48 hours after the last dose of chemotherapy on day 2, patients receive filgrastim (G-CSF) subcutaneously once daily for 7-10 days or until blood counts recover. Treatment repeats every 4 weeks for up to 12 courses in the absence of disease progression or unacceptable toxicity.

Cohorts of 3-6 patients receive escalating doses of acetylcysteine until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. An additional 3 patients are treated at the MTD.

After completion of study treatment, patients are followed periodically.

PROJECTED ACCRUAL: A total of 30 patients will be accrued for this study.