tirapazamine and Thrombocytopenia

Despite improvements in chemotherapy of advanced and metastatic Non-Small-Cell-Lung-Cancer (NSCLC) the prognosis of these patients still remains poor with a 5-year-survival of 2 to 5 %. Due to the high level of hypoxic cells in solid tumors agents with activity in hypoxic milieu as the Benzotriazine compound Tirapazamine (SR 259 075) might improve the therapeutic results. We treated 45 patients with advanced or metastatic Non-Small-Cell-Lung-Cancer (stage IIIb: 20 patients, stage IV: 25 patients) with the combination TPZ 330 mg/m (2) (day 1), Cisplatin 75 mg/m (2) (day 1) and Gemcitabine 1250 mg/m (2) (day 1 and 8) every 3 weeks. With a response rate of 40 % median progression free survival was 6.7 months (4.8 - 8.1 months) and median survival was 8.1 months (7.5 - 12.5 months), (1-year-survival: 35 %). Hematologic and non-hematologic toxicity was moderate (neutropenia CTC grade 3 and 4: 20 %, thrombocytopenia CTC grade 3 and 4: 16 %, nausea and vomiting CTC 3: 5 %). Treatment of advanced and metastatic NSCLC with TPZ in combination with Gemcitabine/Cisplatin was well feasible and showed results recording to currently published data. The results of a following phase III-trial are awaited.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Non-Small-Cell Lung; Cisplatin; Deoxycytidine; Disease-Free Survival; Female; Gemcitabine; Humans; Lung Neoplasms; Male; Middle Aged; Neoplasm Staging; Neutropenia; Survival Analysis; Thrombocytopenia; Tirapazamine; Triazines

Tirapazamine (SR 4233; 3-amino-1,2,4-benzotriazine-1,4-di-N-oxide) is a bioreductive agent exhibiting up to 200 x greater toxicity for hypoxic cells as compared to oxygenated cells. In murine studies, a selective increase in tumor kill was observed when tirapazamine was coadministered with other agents, notably cisplatin. A Phase I study of single-agent tirapazamine administered i.v. every 3 weeks was conducted to determine the toxicity of a schedule for use with systemic chemotherapy. A total of 28 patients were given 50 courses of tirapazamine at doses ranging from 36-450 mg/m2. No tumor responses were observed. Reversible deafness and tinnitus were dose-limiting, with ototoxicity observed in 1 of 6 patients treated at 330 mg/m2, 1 of 4 patients treated at 390 mg/m2, and 3 of 3 patients treated at 450 mg/m2. Muscle cramps, nausea, and vomiting were also observed. Pharmacokinetic studies revealed a greater than dose-proportional increase in the area under the plasma concentration x time curve (AUCs) of the two major metabolites. Patients who developed ototoxicity generally showed higher plasma AUC values for the parent drug and metabolites. The mean plasma tirapazamine AUC at 330 mg/m2 was 1026.5 microgram/ml x min (range 863. 8-1252.3), but no pharmacokinetic data are available for the solitary patient who developed otoxicity at this dose level. These AUC values were in the (estimated) range required for therapeutic effect in murine studies. Ototoxicity was not observed when the AUC of tirapazamine was equal to or less than 1252 microgram/ml x min. The dose of 330 mg/m2 was therefore chosen as an appropriate level for combination chemotherapy studies.

Topics: Adult; Aged; Antineoplastic Agents; Drug Administration Schedule; Female; Humans; Male; Middle Aged; Muscle Cramp; Nausea; Neoplasms; Thrombocytopenia; Tirapazamine; Triazines; Vomiting