Ribonucleotide reductase (RNR) is an enzyme involved in the de novo synthesis of deoxyribonucleotides, which are critical for DNA replication and DNA repair. Triapine is a small-molecule RNR inhibitor. A phase I trial studied the safety of triapine in combination with cisplatin-paclitaxel in patients with advanced stage or metastatic solid tumor cancers in an effort to capitalize on disrupted DNA damage repair. A total of 13 patients with various previously treated cancers were given a 96-h continuous intravenous (i.v.) infusion of triapine (40-120 mg/m(2)) on day 1, and then 3-h i.v. paclitaxel (80 mg/m(2)) followed by 1-h i.v. cisplatin (50-75 mg/m(2)) on day 3. This combination regimen was repeated every 21 days. The maximum tolerated dose (MTD) for each agent was identified to be triapine (80 mg/m(2)), cisplatin (50 mg/m(2)), and paclitaxel (80 mg/m(2)). Common grade 3 or 4 toxicities included reversible anemia, leukopenia, thrombocytopenia, or electrolyte abnormalities. The combination regimen of triapine-cisplatin-paclitaxel resulted in no objective responses; however, five (83%) of six patients treated at the MTD had stable disease between 1 and 8 months duration. This phase I study showed that the combination regimen of triapine-cisplatin-paclitaxel was safe and provides a rational basis for a follow-up phase II trial to evaluate efficacy and progression-free survival in women with metastatic or recurrent uterine cervix cancer.