tirapazamine and Adenocarcinoma

This prospective, randomized phase III intergroup trial of the Gynecologic Oncology Group and National Cancer Institute of Canada Clinical Trials Group was designed to test the effectiveness and safety of adding the hypoxic cell sensitizer tirapazamine (TPZ) to standard cisplatin (CIS) chemoradiotherapy in locally advanced cervix cancer.. Patients with locally advanced cervix cancer were randomly assigned to CIS chemoradiotherapy versus CIS/TPZ chemoradiotherapy. Primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS) and tolerability.. PFS was evaluable in 387 of 402 patients randomly assigned over 36 months, with enrollment ending in September 2009. Because of the lack of TPZ supply, the study did not reach its original target accrual goal. At median follow-up of 28.3 months, PFS and OS were similar in both arms. Three-year PFS for the TPZ/CIS/RT and CIS/RT arms were 63.0% and 64.4%, respectively (log-rank P = .7869). Three-year OS for the TPZ/CIS/RT and CIS/RT arms were 70.5% and 70.6%, respectively (log-rank P = .8333). A scheduled interim safety analysis led to a reduction in the starting dose for the TPZ/CIS arm, with resulting tolerance in both treatment arms.. TPZ/CIS chemoradiotherapy was not superior to CIS chemoradiotherapy in either PFS or OS, although definitive commentary was limited by an inadequate number of events (progression or death). TPZ/CIS chemoradiotherapy was tolerable at a modified starting dose.

Topics: Adenocarcinoma; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Canada; Carcinoma, Adenosquamous; Carcinoma, Squamous Cell; Chemoradiotherapy; Chi-Square Distribution; Cisplatin; Disease Progression; Disease-Free Survival; Female; Humans; Kaplan-Meier Estimate; Middle Aged; Neoplasm Staging; Proportional Hazards Models; Prospective Studies; Time Factors; Tirapazamine; Treatment Outcome; Triazines; United States; Uterine Cervical Neoplasms

Hypoxia is an adverse prognostic factor in locoregionally advanced cervical cancer treated with radiation. The aim of this phase I study was to develop a well-tolerated regimen that added tirapazamine to the standard regimen of radiation and weekly low-dose cisplatin.. Eligible patients had previously untreated carcinoma of the cervix, stages IB2 to IVA. The starting schedule was radiotherapy (45-50.4 Gy external beam radiation followed by brachytherapy), with concomitant weekly intravenous cisplatin, 40 mg/m on weeks 1 to 6 and weekly intravenous tirapazamine, 290 mg/m in weeks 1 to 5.. Eleven patients were enrolled. The median age was 52 years (range, 31-65 years). Ten patients had squamous cell carcinoma and 1 patient had adenocarcinoma; 5 patients had stage 1B2 disease, 1 had stage IIA, 3 had stage IIB-3, 1 had stage IIIB, and 1 had stage IVA. The first 2 patients on dose level 1 experienced a dose-limiting toxicity (DLT): 1 experienced grade 3 alanine amino transferase elevation and grade 4 pulmonary embolism, and 1 experienced grade 3 ototoxicity. Doses were decreased to dose level -1 with a 30-mg/m dose of cisplatin and a 260-mg/m dose of tirapazamine. Three patients were treated without any DLTs. Six patients were then treated on dose level -1a: a 35-mg/m dose of cisplatin and a 260-mg/m doses of tirapazamine with 2 DLTs--grade 3 neutropenia with dose omission and grade 4 pulmonary embolism with major hemodynamic compromise. Three of 10 evaluable patients have experienced locoregional failure.. The combination of weekly tirapazamine and cisplatin with radiation for locally advanced cervical cancer was associated with more toxicity than anticipated with the recommended dose level being tirapazamine 260 mg/m and cisplatin 30 mg/m. Further study of this weekly schedule is not warranted.

Topics: Adenocarcinoma; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Cisplatin; Combined Modality Therapy; Female; Humans; Middle Aged; Neoplasms, Squamous Cell; Tirapazamine; Triazines; Uterine Cervical Neoplasms

Tirapazamine (TPZ), a bioreductive drug with selective toxicity for hypoxic cells in tumors, is currently in Phase III clinical trials. It has been suggested to have a dual mechanism of action, both generating DNA radicals and oxidizing these radicals to form DNA breaks; whether the second (radical oxidation) step is rate-limiting in cells is not known. In this study we exploit the DNA radical oxidizing ability of the 1-N-oxide metabolite of TPZ, SR 4317, to address this question. SR 4317 at high, but nontoxic, concentrations potentiated the hypoxic (but not aerobic) cytotoxicity of TPZ in all four of the human tumor cell lines tested (HT29, SiHa, FaDu, and A549), thus providing a 2-3-fold increase in the hypoxic cytotoxicity ratio. In potentiating TPZ, SR 4317 was 20-fold more potent than the hypoxic cell radiosensitizers misonidazole and metronidazole but was less potent than misonidazole as a radiosensitizer, suggesting that the initial DNA radicals from TPZ and radiation are different. SR 4317 had favorable pharmacokinetic properties in CD-1 nude mice; coadministration with TPZ provided a large increase in the SR 4317 plasma concentrations relative to that for endogenous SR 4317 from TPZ. It also showed excellent extravascular transport properties in oxic and anoxic HT29 multicellular layers (diffusion coefficient 3 x 10(-6) cm(2)s(-1), with no metabolic consumption). Coadministration of SR 4317 (1 mmol/kg) with TPZ at a subtherapeutic dose (0.133 mmol/kg) significantly enhanced hypoxic cell killing in HT29 tumor xenografts without causing oxic cell killing, and the combination at its maximum tolerated dose was less toxic to hypoxic cells in the retina than was TPZ alone at its maximum tolerated dose. This study demonstrates that benzotriazine mono-N-oxides have potential use for improving the therapeutic utility of TPZ as a hypoxic cytotoxin in cancer treatment.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Cell Hypoxia; Cell Line, Tumor; Cell Survival; Colonic Neoplasms; Drug Synergism; Female; Humans; Lung Neoplasms; Mice; Pharyngeal Neoplasms; Tirapazamine; Triazines; Uterine Cervical Neoplasms

Recent data have shown that the in vitro and in vivo cytotoxicity of bioreductive drugs could be significantly increased when combined with chemotherapy drugs such as cisplatinum, depending on the timing of administration. The aim of this study was to define the toxicity (animal lethality) and the activity (growth delay assay, excision assay) of a bioreductive drug, tirapazamine, alone and combined with chemotherapy agents (5-FU, VP16, bleo, DTIC and c-DDP) on nude mice bearing xenografted human tumours: a rectal carcinoma (HRT18) and a melanoma (Na11+). Animal lethality was markedly increased when tirapazamine at the lethal dose 10% was combined with the other drugs. For the HRT18 tumour the combination of tirapazamine and bleomycin significantly increased the delay of regrowth compared with bleomycin alone (P = 0.04) and was more cytotoxic than tirapazamine alone (P = 0.04). For the Na11+ tumours the combination of tirapazamine with VP16 significantly increased tumour doubling time compared with the controls (P = 0.001) or VP16 alone. The combination of tirapazamine and VP16 was more cytotoxic than VP16 alone (P = 0.0001). When compared with c-DDP or tirapazamine alone, there was a significant decrease in plating efficiency when tirapazamine and c-DDP were given at the same time (P = 0.04), but not when tirapazamine was given 3 h before c-DDP. In conclusion, tirapazamine was shown to be cytotoxic against clonogenic human tumour cells. Its efficacy in vivo may depend on its combination with already active chemotherapy drugs on the tumour model used. The timing of administration may be less important than previously thought.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Bleomycin; Cell Division; Cisplatin; Dacarbazine; Drug Screening Assays, Antitumor; Etoposide; Fluorouracil; Humans; Melanoma; Mice; Mice, Nude; Rectal Neoplasms; Tirapazamine; Transplantation, Heterologous; Triazines

Solid tumours contain hypoxic cells which are resistant to radiotherapy. This study compares the efficacy of several strategies to counteract diffusion-limited hypoxia, or intermittent hypoxia in a fractionated regimen of 1 to 6 x 2 Gy.. Nicotinamide (250 mg/kg), perflubron emulsion (Oxygent) (4 ml/kg), tirapazamine (SR4233) (0.10 mmol/kg) and carbogen breathing, administered alone or in combination, were investigated on two tumour cell lines: EMT6 (a rodent mammary carcinoma) and HRT18 (a human rectal adenocarcinoma) using a clonogenic assay. The radiosensitizing effect of the agents was assessed after 1 and 6 x 2 Gy for drugs used alone, and 1, 2, 4, 6 x 2 Gy for drugs used in combination.. At the end of the fractionated radiation regimen, the combination of nicotinamide + carbogen induced the greatest radiosensitization for EMT6 tumours, while greatest radiosensitization of HRT18 was obtained with nicotinamide + carbogen + tirapazamine.. The efficacy of the strategies for overcoming hypoxia using a fractionated regimen depends on the tumour cell line. These differences could be linked to differences in the initial percentages of acute and chronic hypoxic cells, and to changes in the two types of hypoxia during treatment.

Topics: Adenocarcinoma; Animals; Carbon Dioxide; Cell Hypoxia; Emulsions; Female; Fluorocarbons; Humans; Hydrocarbons, Brominated; Mammary Neoplasms, Experimental; Mice; Niacinamide; Oxygen; Radiation Tolerance; Radiation-Sensitizing Agents; Radiotherapy; Radiotherapy Dosage; Rectal Neoplasms; Tirapazamine; Triazines; Tumor Cells, Cultured

SR-4233 (Tirapazamine) is a hypoxic cell selective cytotoxic agent currently in Phase I clinical trial. Although SR-4233 is selectively cytotoxic toward hypoxic cells some cytotoxicity toward normally oxygenated cells also occurs. SR-4233 (500 microM, 1 h) killed about 70% of normally oxygenated and 99% of hypoxic human MCF-7 breast carcinoma cells. Using a polarographic chamber and a Clark O2 electrode the O2 consumption of MCF-7 cells was measured in the presence or absence of SR-4233 (500 microM) or other inhibitors or uncouplers of oxidative phosphorylation. MCF-7 cells exhibited increased O2 consumption in the presence of SR-4233 alone and after treatment with oligomycin but not after treatment with retenone. The pattern of O2 consumption observed after treatment with SR-4233 was very similar to that seen when the cells were treated with the classical uncoupler FCCP. After 1 h of exposure to SR-4233 (500 microM) the cells were not responsive to treatment with oligomycin or FCCP for at least 3 h, but by 24 h post exposure to SR-4233 the cells had regained responsiveness to both FCCP and oligomycin. These results indicate that in normally oxygenated cells SR-4233 acts as an uncoupler of oxidative phosphorylation so that the cells continue to consume O2 but no ATP is produced. This condition can lead to ATP depletion especially in respiration intensive tissues and may provide an explanation for the muscle cramping observed in some patients treated with SR-4233.

Topics: Adenocarcinoma; Breast Neoplasms; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Electron Transport Complex IV; Female; Humans; In Vitro Techniques; Oxygen Consumption; Tirapazamine; Triazines; Tumor Cells, Cultured; Uncoupling Agents

Local hyperthermia and the hypoxic cytotoxin SR 4233 were administered to nude mice with 693 +/- 47 mm3 (mean +/- SE) s.c. HCT-8 human colonic adenocarcinoma xenografts in an attempt to enhance the antitumor effects of radioimmunotherapy. Biodistribution studies revealed preferential binding of NR-Lu-10, a murine monoclonal antibody, to the tumors compared with an isotype-matched control antibody, CCOO16-3.A single injection of 25 microCi 90Y-NR-Lu-10 significantly inhibited tumor growth (control versus 90Y-NR-Lu-10: P = 0.048). The administration of hyperthermia at 41.5 degrees C for 1 h immediately following the injection of 111In-labeled NR-Lu-10 up-regulated tumor-associated antigen expression and increased antibody uptake in the tumors by 73% (P = 0.001) without significantly affecting antibody uptake in normal tissues. However, the heat treatment did not produce a more homogeneous distribution of the antibodies in the tumors and did not significantly enhance the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.07). The administration of local hyperthermia at 43.0 degrees C for 1 h, on the other hand, had direct cytotoxic effects (P = 0.03) and enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.01). SR 4233 also enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.03). The greatest antitumor effects were observed when both hyperthermia at 43.0 degrees C and SR 4233 were administered in combination with 90Y-NR-Lu-10 (P = 0.002). No toxicity was produced by the local hyperthermia, and the only toxicities produced by 90Y-NR-Lu-10 and SR 4233 were neutropenia and weight loss.

Topics: Adenocarcinoma; Animals; Antibodies, Monoclonal; Antineoplastic Agents; Autoradiography; Cell Division; Cell Hypoxia; Colonic Neoplasms; Combined Modality Therapy; Female; Humans; Hyperthermia, Induced; Immunotoxins; Indium Radioisotopes; Mice; Mice, Inbred BALB C; Mice, Nude; Radiation-Sensitizing Agents; Radioimmunoassay; Radioimmunotherapy; Tirapazamine; Tissue Distribution; Transplantation, Heterologous; Triazines; Yttrium Radioisotopes

Radioimmunotherapy is hindered by the slow penetration of antibody molecules into tumors. Cells that are poorly targeted by antibody, because of their distance from feeding blood vessels, receive the lowest radiation dose, and this problem is compounded if there are radioresistant hypoxic cells present. It would be desirable to combine radioimmunotherapy with an agent that is preferentially toxic to these cells. SR 4233 is a potent hypoxic cytotoxin, and it was combined with 131I-NR-LU-10 to treat LS174T human colon adenocarcinoma multicell spheroids and nude mouse xenografts for these studies. Under conditions of severe hypoxia (< 0.01% O2), 2 h of pretreatment or 18 h of simultaneous treatment with SR 4233 did not significantly enhance the effectiveness of 131I-NR-LU-10 in spheroids. However, under aerobic conditions with a 10% fraction of hypoxic cells, there was more toxicity than would be predicted from simple additivity. Xenografts treated with 131I-NR-LU-10 + SR 4233 had a growth delay that was significantly longer than that achieved with 131I-NR-LU-10 alone. In both spheroids and xenografts, combined treatment produced about 10 times more cell killing than 131I-NR-LU-10 alone. The lack of enhancement in spheroids under complete hypoxia suggests that SR 4233 does not sensitize hypoxic cells to radiation damage. The results with aerobic spheroids and in vivo, where a portion of the cells were hypoxic, could be explained by the targeting of different cell populations (hypoxic and aerobic) by each therapeutic modality. This effect should also be enhanced by reoxygenation and reestablishment of the hypoxic fraction during treatment, thus allowing more than the initially hypoxic fraction of cells to be killed by the SR 4233.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Colonic Neoplasms; Combined Modality Therapy; Humans; In Vitro Techniques; Iodine Radioisotopes; Mice; Mice, Nude; Neoplasms, Experimental; Radiation-Sensitizing Agents; Radioimmunotherapy; Tirapazamine; Transplantation, Heterologous; Triazines; Tumor Cells, Cultured