Enhancement of chemotherapy and radiotherapy of murine tumours by AQ4N, a bioreductively activated anti-tumour agent

• Published in: British journal of cancer Vol. 82; no. 12; pp. 1984 - 1990
• Main Authors: PATTERSON, L. H, MCKEOWN, S. R, RUPARELIA, K, DOUBLE, J. A, BIBBY, M. C, COLE, S, STRATFORD, I. J
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing Group 01.06.2000
• Subjects: Animals; Anthraquinones - therapeutic use; Antineoplastic agents; Antineoplastic Agents - therapeutic use; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Biological and medical sciences; Cancer research; Cancer therapies; Cell Hypoxia - drug effects; Chemotherapy; Drug Administration Schedule; Drug dosages; Drug Synergism; Experiments; Hypoxia; Male; Medical research; Medical sciences; Mice; Mice, Inbred Strains; Neoplasms, Experimental - drug therapy; Neoplasms, Experimental - radiotherapy; Pharmaceutical sciences; Pharmacology. Drug treatments; Pharmacy; Prodrugs - therapeutic use; Radiation therapy; Regular; Toxicity; Tumors; United Kingdom > UK; Antineoplastic agent; Aziridine derivatives; Chemical reduction; Organic thioamidophosphate; Platinum II Complexes; Oxygen; Treatment efficiency; Rodentia; Enhancement factor; Prodrug; Malignant tumor; Radiotherapy; Cisplatin; Pathology; Vertebrata; Chemotherapy; Cyclophosphamide; Oxazaphosphinane derivatives; Experimental disease; Mammalia; Treatment; Mouse; Animal; Nitrogen mustard; Thiotepa; Hypoxia
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1054/bjoc.2000.1163

AQ4 (1,4-Bis-[[2-(dimethylamino-N-oxide)ethyl]amino]5,8-dihydroxyanthrace ne-9, 10-dione) is a prodrug designed to be excluded from cell nuclei until bioreduced in hypoxic cells to AQ4, a DNA intercalator and topoisomerase II poison. Thus, AQ4N is a highly selective bioreductive drug that is activated in, and is preferentially toxic to, hypoxic cells in tumours. Five murine tumours (MAC16, MAC26, NT, SCCVII and RIF-1) have been used to investigate the anti-tumour effects of AQ4N. In only one tumour (MAC16) was AQ4N shown to be active as a single agent. However, when combined with methods to increase the hypoxic tumour fraction in RIF-1 (by physical clamping) and MAC26 tumours (using hydralazine) there was a substantial enhancement in anti-tumour effect. Notably, RIF-1 tumours treated with AQ4N (250 mg kg(-1)) followed 15 min later by physically occluding the blood supply to the tumour for 90 min, resulted in a 13-fold increase in growth delay. When combined with radiation or chemotherapy, AQ4N substantially increased the effectiveness of these modalities in a range of in vivo model systems. AQ4N potentiates the action of radiation in both a drug and radiation dose-dependent manner. Further the enhancement observed is schedule-independent with AQ4N giving similar effects when given at any time within 16 h before or after the radiation treatment. In combination with chemotherapy it is shown that AQ4N potentiates the activity of cyclophosphamide, cisplatin and thiotepa. Both the chemotherapeutic drugs and AQ4N are given at doses which individually are close to their estimated maximum tolerated dose (data not included) which provides indirect evidence that in the combination chemotherapy experiments there is some tumour selectivity in the enhanced action of the drugs.