title: Schedule dependence, activity against natural metastases, and cross-resistance of pyrazine diazohydroxide (sodium salt, NSC 361456) in preclinical models in vivo.
abstract: Pyrazine diazohydroxide (sodium salt, NSC 361456; PZDH) is a new antitumor drug with relatively broad activity in initial evaluations against murine leukemias, solid tumors, and two human tumor xenografts in vivo. The present studies were designed to address questions about PZDH activity on different treatment schedules, its activity against metastases, and the extent of its cross-resistance with established drugs. Human LOX amelanotic melanoma xenografts in athymic mice were used to explore schedule dependence and activity against natural metastases, and a series of drug-resistant murine leukemias provided an in vivo cross-resistance profile. Single-dose treatment and prolonged treatment provided equivalent therapeutic responses to PZDH by both the i.p. and i.v. routes in the i.p. LOX model. A s.c. LOX model resulting in spontaneous pulmonary metastases was adapted for bioassay and quantitation of the numbers of LOX cells killed by PZDH among both primary and metastatic cell populations. It was demonstrated that PZDH afforded about 2-log10 orders of magnitude greater cell kill among pulmonary metastases than against primary s.c. LOX tumors in the same mouse. Murine leukemias resistant to doxorubicin (ADR), vincristine (VCR), cisplatin (DDPt), methotrexate (MTX), N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU), and cyclophosphamide (CPA) were not cross-resistant to PZDH. However, both P388 and L1210 leukemia sublines resistant to melphalan (L-PAM) were cross-resistant to PZDH, suggesting that patients previously treated with L-PAM might have less likelihood of response to PZDH than those who had had no opportunity to develop L-PAM resistance. Although these observations should not be applied to clinical studies without due caution, they support clinical evaluation of PZDH as well as continued investigation of its molecular pharmacology.
authors.affiliation: Kettering-Meyer Laboratory, Southern Research Institute, Birmingham, AL 35255-5305.
authors.forename: S D
authors.initials: SD
authors.lastname: Harrison
authors.forename: J
authors.initials: J
authors.lastname: Plowman
authors.forename: D J
authors.initials: DJ
authors.lastname: Dykes
authors.forename: W R
authors.initials: WR
authors.lastname: Waud
authors.forename: D P
authors.initials: DP
authors.lastname: Griswold
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D004351:Drug Resistance; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D007939:Leukemia L1210 / Q000188:drug therapy; D007941:Leukemia P388 / Q000188:drug therapy; D008175:Lung Neoplasms / Q000188:drug therapy / Q000556:secondary; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000556:secondary; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000188:drug therapy*; D011719:Pyrazines / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000970:Antineoplastic Agents; D011719:Pyrazines; C051397:pyrazine-2-diazohydroxide