Synergistic cytotoxicity of buthionine sulfoximine (BSO) and intensive melphalan (L-PAM) for neuroblastoma cell lines established at relapse after myeloablative therapy

Bone Marrow Transplant. 2002 Aug;30(3):135-40. doi: 10.1038/sj.bmt.1703605.


Patients with high-risk neuroblastoma (NB) initially respond to aggressive, alkylator-based therapy only to die from recurrent disease that is refractory to chemotherapy, including alkylating agents. We examined the ability of buthionine sulfoximine (BSO)-mediated glutathione (GSH) depletion to modulate melphalan (L-PAM) resistance in five NB cell lines established after progressive disease following myeloablative therapy (high-dose melphalan, carboplatin, etoposide and total body irradiation) supported by autologous hematopoietic stem cell transplant (AHSCT), and in 15 NB cell lines established at diagnosis or after non-myeloablative therapy (pre-AHSCT). Four of five post-AHSCT NB cell lines and 10 of 15 pre-AHSCT NB cell lines were sensitive to single agent BSO (LC(90) <300 microM BSO), while two of five post-AHSCT lines and one of 15 pre-AHSCT lines showed high-level resistance to L-PAM (LC(90)>30 microM). Fixed ratio analysis demonstrated BSO/L-PAM synergy (combination index <1) for all five post-AHSCT and for all 15 pre-AHSCT cell lines tested. Multi-log cytotoxicity (often exceeding four logs of cell kill) was observed in post-AHSCT L-PAM-resistant cell lines (including p53 non-functional lines) only when clinically achievable concentrations of BSO were combined with myeloablative concentrations of L-PAM. We conclude that most neuroblastoma cell lines, including post-AHSCT NB cell lines that are highly resistant to myeloablative levels of L-PAM and lack p53 function, are sensitive to clinically achievable concentrations of L-PAM and BSO. However, some L-PAM-resistant NB cell lines (especially those lacking p53 function) require dose escalation of L-PAM to myeloablative concentrations in order to demonstrate significant synergistic cytotoxicity. Thus, optimal clinical application of BSO/L-PAM may require AHSCT.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Buthionine Sulfoximine / pharmacology*
  • Cell Survival / drug effects
  • Dose-Response Relationship, Drug
  • Drug Resistance, Neoplasm
  • Drug Synergism
  • Glutathione / drug effects
  • Glutathione / metabolism
  • Humans
  • Melphalan / pharmacology*
  • Myeloablative Agonists / therapeutic use*
  • Neuroblastoma / drug therapy*
  • Neuroblastoma / pathology
  • Recurrence
  • Tumor Cells, Cultured


  • Myeloablative Agonists
  • Buthionine Sulfoximine
  • Glutathione
  • Melphalan