title: Modification of cytotoxic drug resistance by non-immuno-suppressive cyclosporins.
abstract: We have examined the ability of a series of non- or minimally-immunosuppressive analogues of cyclosporin A to modify cytotoxic drug resistance in vitro. The series includes both cyclosporins derived from naturally-occurring compounds and synthetic cyclosporins. In contrast to our previous findings, we now report that several of these analogues are highly effective modifiers of resistance to adriamycin and vincristine in a multidrug resistant subline of the human small cell lung cancer cell line NCI-H69. Two of the analogues (W8-032 and B3-243) maintain considerable activity in the dose range 1-2 micrograms ml-1 whereas little activity remains for cyclosporin A when the dose is reduced to this level. B3-243, however, in contrast to cyclosporin A and W8-032, does itself show growth inhibitory effects in this dose range. Possible clinical trial of these cyclosporins as resistance modifiers will depend upon their in vivo toxicology and pharmacokinetic properties.
authors.affiliation: MRC Clinical Oncology and Radiotherapeutics Unit, Cambridge, UK.
authors.forename: P R
authors.initials: PR
authors.lastname: Twentyman
mesh_terms: D018288:Carcinoma, Small Cell / Q000188:drug therapy*; D002460:Cell Line; D003524:Cyclosporins / Q000494:pharmacology*; D004317:Doxorubicin / Q000627:therapeutic use*; D004347:Drug Interactions; D004351:Drug Resistance; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014750:Vincristine / Q000627:therapeutic use*
chemical_list: D003524:Cyclosporins; D014750:Vincristine; D004317:Doxorubicin