Bone marrow chemoprotection without compromise of chemotherapy efficacy in a rat brain tumor model.
Thiol chemoprotective agents can reduce chemotherapy side effects, but clinical use is limited due to concerns of impaired chemotherapeutic efficacy. We evaluated whether an optimized bone marrow chemoprotection regimen impaired the efficacy of enhanced chemotherapy against rat brain tumors. Nude rats with intracerebral human lung carcinoma xenografts were treated with carboplatin, melphalan, and etoposide phosphate delivered intra-arterially with osmotic blood-brain barrier disruption (n = 8/group). Thiol chemoprotection was N-acetyl-L-cysteine (1000 mg/kg) 60 min before chemotherapy and/or sodium thiosulfate (8 g/m(2)) 4 and 8 h after chemotherapy, when the blood-brain barrier is reestablished. Blood counts were obtained before treatment on day 3 and at sacrifice on day 9. N-acetylcysteine serum clearance half-life was 9 to 11 min. Pretreatment with N-acetylcysteine combined with delayed administration of sodium thiosulfate protected against toxicity toward total white cells, granulocytes, and platelets (P = 0.0016). Enhanced chemotherapy reduced intracerebral tumor volume to 4.3 +/- 1.0 mm(3) compared with 29.1 +/- 4.1 mm(3) in untreated animals (P < 0.0001). Tumor volume was 3.7 +/- 0.6 mm(3) in rats that received N-acetylcysteine before and sodium thiosulfate after chemotherapy. The data indicate the efficacy of enhanced chemotherapy for rat brain tumors was not affected by thiol chemoprotection that provided excellent protection for hematological toxicity. Negative interactions of thiols with antitumor efficacy were avoided by temporal and spatial separation of chemoprotectants and chemotherapy.
Neuwelt
Edward A
EA
Oregon Health Sciences University, Department of Neurology, Portland 97239, USA. neuwelte@ohsu.edu
Pagel
Michael A
MA
Kraemer
Dale F
DF
Peterson
Darryl R
DR
Muldoon
Leslie L
LL
D000111:Acetylcysteine / Q000493:pharmacokinetics / Q000633:toxicity*; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001853:Bone Marrow / Q000187:drug effects*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D018890:Chemoprevention; D004195:Disease Models, Animal; D004347:Drug Interactions; D008658:Inactivation, Metabolic; D020011:Protective Agents / Q000493:pharmacokinetics / Q000633:toxicity*; D051381:Rats; D020318:Rats, Long-Evans; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D020011:Protective Agents; D013438:Sulfhydryl Compounds; D000111:Acetylcysteine