WR-1065, the active metabolite of amifostine (Ethyol), does not inhibit the cytotoxic effects of a broad range of standard anticancer drugs against human ovarian and breast cancer cells

Effects of amifostine on endometriosis, comparison with N-acetyl cysteine, and leuprolide as a new treatment alternative: a randomized controlled trial

PURPOSE

To assess the effects of amifostine, N-acetyl cysteine (NAC), and leuprolide as a scavenger in a rat endometriosis model.

METHODS

This is a prospective randomized animal study. Setting The Animal Laboratory of Medical University. Animals 40 rats were used for transplantation of an autologous fragment of endometrial tissue onto the inner surface of the abdominal wall. After allowing 3 weeks for growth, laparotomies were performed to check the implants. Then animals were randomized into four groups: Group I amifostine (200 mg/day loading dose after 20 mg/kg/day, p.o.); Group II NAC (200 mg/day, p.o.); Group III leuprolide acetate 1 mg/kg single dose, sc; and Group IV (controls) no medication. Three weeks later, implants were evaluated morphologically. Serum and peritoneal TNF-alpha levels were evaluated. The transmission electron microscopic examination of the peritoneal samples and ovaries was also performed.

RESULTS

Leuprolide acetate, amifostine and NAC caused significant decreases in the mean implant areas and significant decreases in serum and peritoneal TNF-alpha levels. On comparing all groups, these reductions were higher in Group II. According to the transmission electron microscopic findings, leuprolide seems to be protecting normal structure of peritoneum best when compared to the other groups.

CONCLUSIONS

Amifostine, NAC and leuprolide caused regression of endometriosis in this experimental rat model by a yet unsettled mechanism.

Effect of amifostine on the cytotoxicity of daunorubicin and daunoxome in tumor and normal cells

Anthracyclines are powerful cytotoxic agents, used as first-line treatment of leukemias and many other tumors, but host-tissue toxicity is their main dose-limiting factor. However, their therapeutic effects depend not only on the toxicity, hence on the dose, but also on drug resistance. Among the mechanisms that can account for cell sensitivity to anthracyclines, there is an overexpression of drug transport proteins, like the transmembrane P-glycoprotein (PGP), the multidrug- resistance-related protein (MRP) and the lung-resistance-related protein (LRP). Attempts to reduce the toxicity of chemotherapeutic agents without affecting their efficacy have been made using liposomal anthracyclines or cytoprotective agents, as Amifostine. The aim of this study was to evaluate and compare the toxic effects of Daunorubicin, in normal or liposomal formulation, used in combination with WR1065, the active metabolite of Amifostine, against normal and tumor cells. In conclusion these data show that the preincubation with WR-1065 does not inhibit the drug toxic effect on blast cells and on tumor cell lines, independently by their multidrug resistance phenotype, but has a cytoprotective effect on stem cells causing a drug cytotoxicity reduction of 10-20%. This advantage is even higher using the liposomal formulation of DNR. Therefore, Amifostine can offer a chance of protecting normal cells from the toxicity of anthracyclines, in normal or liposomal formulation. The combination of liposomal anthracyclines with Amifostine can confer further advantages in management of leukemic patients, especially the elderly where treatment toxicity is a main problem. These patients may be candidates for alternative therapeutic strategies and the combination of DNX and Amifostine is an attractive treatment for these cases where a low nonhematological toxicity is required.

The potential influence of cell protectors for dose escalation in cancer therapy: an analysis of amifostine

The attempt to increase the therapeutic ratio in an effort to improve survival or quality of life is the goal of modern cancer therapy. It is commonly accepted that local and systemic tumor control would increase if the dose intensity of antineoplastic drugs, radiation therapy, or the combination were increased. Radiation dose escalation using intensity-modulated radiation therapy (IMRT), accelerated or hypofractionated radiation schemes, and multidrug chemotherapy regimens are being used to try to increase tumor kill while inflicting minimal injury to normal tissue. Modern chemoradiation techniques have led to improved local regional control and increased cure rates, but the potentially severe and debilitating adverse effects of the therapies prevent them from reaching the ultimate goal of curing the disease while leaving the patient with a good quality of life. Cell protectants such as amifostine function by reducing the effects of therapy on normal cells while maintaining tumor sensitivity to the therapy. In various studies, amifostine has been analyzed and appears to be a potentially powerful adjuvant to current cancer therapy. Administering amifostine may allow dose escalation with less or equal risk to surrounding normal tissues. This could improve therapeutic efficacy, survival, and quality of life for cancer patients.

A randomized trial of amifostine and carmustine-containing chemotherapy to assess lung-protective effects

We conducted a randomized, double blind, placebo-controlled multi-institutional trial to assess the ability of amifostine to protect patients against acute lung injury associated with cyclophosphamide/cisplatin/carmustine (BCNU) (STAMP I), a BCNU-containing high dose chemotherapy regimen used with hematopoietic cell transplantation. Amifostine was administered in a dose of 740 mg/m(2) for 2 doses preceding administration of BCNU, the presumed pulmonary-toxic component of the regimen. The trial was stopped after 79 patients were randomized and a planned interim analysis demonstrated that it was unlikely that pulmonary cytoprotection would be detected with further accrual. We conclude that amifostine, used in the dose and schedule we tested, does not reduce the incidence of acute lung injury produced by STAMP I. Further, we suggest that amifostine use with BCNU in other contexts and with clinically achievable doses is unlikely to protect the lung from BCNU-associated acute injury.

Amifostine: is there evidence of tumor protection?

A large body of experimental evidence suggests that amifostine (Ethyol, WR-2721; MedImmune, Inc, Gaithersburg, MD) is a selective cytoprotector of normal tissues. Nevertheless, several experimental studies, most of which were conducted in the early 1980s, suggest that amifostine may protect tumor tissues, although to a much lower degree than its protective effect on normal tissues. Based on a critical literature review, we conclude that any experimental evidence suggesting tumor protection is weak. The effects of anesthesia and hypotension on normal and tumor tissue oxygenation status of animals, the consequences of such events on amifostine activity, and the impact of this complex situation on host immunity and radiotherapy efficacy in the experimental setting do not reliably simulate the clinical setting. Analyses of radiobiologic and histologic results of the Canine Sarcoma Study show that, if any conclusion is to be made, amifostine protected normal tissues and preserved (or even enhanced) the antitumor activity of radiotherapy. The Ormaplatin Study clearly showed a 10-fold decreased concentration of platinum in tumor compared with normal tissues, and does not therefore support evidence of lack of amifostine selectivity. Finally, not one clinical study suggests tumor protection with amifostine. On the contrary, the majority of clinical data strongly suggest that patients who receive amifostine with radiotherapy and/or chemotherapy do better than controls. Rather than organizing large-scale, randomized clinical trials to exclude tumor protection by amifostine, it seems more useful to design trials that would measure amifostine benefits in terms of improved quality of life, tumor control, and survival rates in patients being treated with standard or novel chemotherapy/radiotherapy regimens.

Amifostine in clinical oncology: current use and future applications

Amifostine (Ethyol), an inorganic thiophosphate, is a selective broad-spectrum cytoprotector of normal tissues that provides cytoprotection against ionizing radiation and chemotherapeutic agents, thus preserving the efficacy of radiotherapy and chemotherapy. This review summarizes the preclinical data and clinical experience with amifostine, and provides insight into future clinical directions. Amifostine, an inactive pro-drug, is transformed to an active thiol after dephosphorylation by alkaline phosphatase found in the normal endothelium. The absence of alkaline phosphatase in the tumoral endothelium and stromal components, and the hypovascularity and acidity of the tumor environment, may explain its cytoprotective selectivity. The cytoprotective mechanism of amifostine is complicated, involving free radical scavenging, DNA protection and repair acceleration, and induction of cellular hypoxia. Intravenous administration of amifostine 740-900 mg/m(2) before chemotherapy and 250-350 mg/m(2) before each radiotherapy fraction are widely used regimens. The US Food and Drug Administration has approved the use of amifostine as a cytoprotector for cisplatin chemotherapy and for radiation-induced xerostomia. Ongoing trials are being conducted to determine the efficacy of amifostine in reducing radiation-induced mucositis and other toxicities. Novel schedules and routes of administration are under investigation, and may further simplify the use of amifostine and considerably broaden its applications.

A randomized phase II study of amifostine used as stem cell protectant in non-hodgkin lymphoma patients receiving cisplatin-based salvage chemotherapy prior to stem cell transplant

Stem cell mobilization may be inadequate in many lymphoma patients in need for autologous stem cell transplant (SCT). In this study, we sought to evaluate a potential role of amifostine as a stem cell chemoprotective agent in lymphoma patients receiving DHAP chemotherapy in preparation for high-dose chemotherapy (HDC) and stem cell transplant (SCT). In the beginning of the DHAP course, patients were randomized 1:1 to receive amifostine at 740 mg/m(2). Stem cells were mobilized with GCSF after the last cycle of DHAP. Stem cell collection started upon ANC recovery over 1000/mm(3). Standard 10 lt. apheresis daily with a goal of a minimum of 2 x 10(6) stem cells/kg were performed. Twenty-one patients have been enrolled; 10 received amifostine pretreatment (age, 20-64) and 11 were randomized to the control arm (age, 18-63). Prior chemotherapy was balanced in the two groups. The median number of DHAP treatments for each group was 2. Amifostine was well tolerated and was associated with higher stem cell collection. Toxicity and time to engraftment were comparable between the two groups. Our preliminary results may suggest a role of amifostine in protecting stem cells during salvage chemotherapy, thus facilitating stem cell collection.

A Phase II trial of cisplatin plus WR-2721 (amifostine) for metastatic breast carcinoma: an Eastern Cooperative Oncology Group Study (E8188)

BACKGROUND

Cisplatin has minimal antitumor activity when used as second- or third-line treatment of metastatic breast carcinoma. Older reports suggest an objective response rate of 8% when 60-120 mg/m2 of cisplatin is administered every 3-4 weeks. Although a dose-response effect has been observed with cisplatin, the dose-limiting toxicities associated with cisplatin (e.g., nephrotoxicity, ototoxicity, and neurotoxicity) have limited its use as a treatment for breast carcinoma. WR-2721 or amifostine initially was developed to protect military personnel in the event of nuclear war. Amifostine subsequently was shown to protect normal tissues from the toxic effects of alkylating agents and cisplatin without decreasing the antitumor effect of the chemotherapy. Early trials of cisplatin and amifostine also suggested that the incidence and severity of cisplatin-induced nephrotoxicity, ototoxicity, and neuropathy were reduced.

METHODS

A Phase II study of the combination of cisplatin plus amifostine was conducted in patients with progressive metastatic breast carcinoma who had received one, but not more than one, chemotherapy regimen for metastatic disease. Patients received amifostine, 910 mg/m2 intravenously over 15 minutes. After completion of the amifostine infusion, cisplatin 120 mg/m2 was administered over 30 minutes. Intravenous hydration and mannitol was administered before and after cisplatin. Treatment was administered every 3 weeks until disease progression.

RESULTS

Forty-four patients were enrolled in the study of which 7 (16%) were ineligible. A median of 2 cycles of therapy was administered to the 37 eligible patients. Six partial responses were observed for an overall response rate of 16%. Most patients (57%) stopped treatment because of disease progression. Neurologic toxicity was reported in 52% of patients. Seven different life-threatening toxicities were observed in patients while receiving treatment.

CONCLUSIONS

The combination of cisplatin and amifostine in this study resulted in an overall response rate of 16%. Neither a tumor-protective effect nor reduced toxicity to normal tissues was observed with the addition of amifostine to cisplatin in this trial.

Amifostine does not inhibit the toxic effects of anthracycline derivates or mitoxantrone on MDR tumor cell lines

In this work three human cell lines with multidrug resistance (MDR) caused by a P-glycoprotein (PGP) overexpression, CEM VLB, HL60 DNR, LOVO DX and two cell lines with MDR associated with a multidrug related protein (MRP) or a lung resistance-related protein (LRP) overexpression named GLC4 ADR and SW1573/2R120 were tested for Amifostine protection against Daunorubicin, Doxorubicin, Idarubicin and Mitoxantrone toxicity. This class of anticancer agents was chosen because they are commonly used in the first line treatments of acute leukemias where a PGP, an LRP or an MRP overexpression often occurs even at onset. A 7-day incubation with escalating doses of anticancer agents with or without a 15 minute preincubation in Amifostine or its active metabolite WR-1065 were used. In conclusion, in none of the MDR positive and negative cell lines did Amifostine modify the toxicity of the anticancer drugs. The observation that even the WR-1065 metabolite gave no protection against Anthracyclines toxicity strengthened the data and provided confirmation for the further in vivo testing of the safety and efficacy of Amifostine in leukemias.

Amifostine does not protect malignant lymphoma cell lines from the cytotoxic effects of various chemotherapeutics in vitro

The effect of amifostine on the cytotoxicity of melphalan, BCNU, doxorubicin and etoposide in lymphoma cell lines; HTB-61 (Burkitt), HTB-142 (nonspesified neck lymphoma), HTB-146 (Hodgkin's) and HTB 176 (Sezarýs syndrome) and a normal human fibroblast cell line was studied in vitro. Amifostine decreased etoposide induced cell kill in the fibroblast cell line. Pretreatment with the same amifostine concentration did not decrease the cytotoxic effects of etoposide, doxorubicin, melphalan and carmustine in lymphoma cell lines. Moreover, it even enhanced the cell killing effects of chemotherapeutics in especially HTB61 cell line. Our results indicate that amifostine does not decrease cytotoxicity of the chemotherapeutics and favor the testing of this drug in accordance with lymphoma treatments in clinical trials.

Cardiovascular considerations with anthracycline use in patients with cancer

Anthracyclines are important chemotherapeutic agents that are used for the treatment of various malignancies in both adults and children, but their usefulness has been limited by cardiotoxicity that is usually dose related. Oxidative injury appears to be the cause of myocardial dysfunction when using these drugs. Screening for early myocardial injury with troponin testing, echocardiography, and radionuclide examinations has reduced the incidence of chronic cardiac dysfunction. Various anthracycline analogues have been developed that have less cardiotoxicity. Dexrazoxane, an iron chelator, and the radioprotective agent amifostine protect against cardiac injury, thus allowing the use of higher doses of anthracyclines. Other strategies that have been evaluated are dietary glutamine supplementation and the use of the antioxidant probucol.

Amifostine: mechanisms of action underlying cytoprotection and chemoprevention

Amifostine is an important drug in the new field of cytoprotection. It was developed by the Antiradiation Drug Development Program of the US Army Medical Research and Development Command as a radioprotective compound and was the first drug from that Program to be approved for clinical use in the protection of dose limiting normal tissues in patients against the damaging effects of radiation and chemotherapy. Its unique polyamine-like structure and attached sulfhydryl group give it the potential to participate in a range of cellular processes that make it an exciting candidate for use in both cytoprotection and chemoprevention. Amifostine protects against the DNA damaging effects of ionizing radiation and chemotherapy drug associated reactive species. It possesses anti-mutagenic and anti-carcinogenic properties. At the molecular level, it has been demonstrated to affect redox sensitive transcription factors, gene expression, chromatin stability, and enzymatic activity. At the cellular level it has important effects on growth and cell cycle progression. This review focuses on relating its unique chemical design to mechanisms of action that underlie its broad usefulness as both a cytoprotective and chemopreventive agent for use in cancer therapy.

The effect of amifostine on the in vitro cytotoxicity of chemotherapeutic agents in three epithelial ovarian carcinoma cell lines

OBJECTIVES

Amifostine protects against a spectrum of toxicities induced by chemotherapy without affecting tumor cell kill. This is supported by clinical data and in vivo animal studies. However, there is a paucity of data on its effect on the tumor cytotoxicity of several chemotherapeutic agents used in recurrent epithelial ovarian cancer. This study compares in vitro cytotoxicity before and after addition of amifostine.

METHODS

Three epithelial ovarian carcinoma cell lines (SKOV3, 420, 429) were exposed to cis-platinum, paclitaxel, doxorubicin, etoposide, 5-fluorouracil, bleomycin, 4-epidoxorubicin, 4-HC (activated cyclophosphamide), vincristine, actinomycin D, mitomycin C, and topotecan. Cells were pretreated with either 0 or 1.2 mM amifostine. Tumor cell kill after 6 days of incubation was measured using the ATP cell viability assay. Paired samples Student's t statistic was used to test the difference in mean ATP levels between drug-treated samples with and without pretreatment with amifostine.

RESULTS

SKOV3 was sensitive to paclitaxel, actinomycin D, 4-epidoxorubicin, and vincristine. Cell line 420 was sensitive to paclitaxel, etoposide, and 5-fluorouracil. Cell line 429 was sensitive to paclitaxel and 5-fluorouracil. There was no significant difference in the mean ATP levels between drug-treated samples with and without pretreatment with amifostine for each of the sensitive drugs in all three cell lines. Similarly, there was no significant difference in the mean ATP levels in cis-platinum and 4-HC treated samples with and without pretreatment with amifostine.

CONCLUSIONS

These results show that at the cellular level amifostine did not protect epithelial ovarian carcinoma cells against tumor cell kill.

Reducing the toxicity of anticancer therapy: new strategies

Cytoprotective agents offer opportunities to reduce the treatment-related toxicity of anticancer therapy and perhaps to increase the dose and dose intensity of radiation and chemotherapy. One such agent is amifostine, an organic thiophosphate. Amifostine selectively protects normal tissues and provides broad-spectrum protection for a variety of organs while remaining minimally toxic. Clinical studies have demonstrated that amifostine protects against myelotoxicity, nephrotoxicity, neurotoxicity, mucositis and esophagitis in patients treated with alkylating and platinum agents, paclitaxel and radiation therapy. In addition, preclinical studies suggest the possibility of protection against anthracycline-induced cardiotoxicity and radiation- and chemotherapy-induced mutagenicity. Preclinical and clinical studies have not demonstrated any diminution of antitumor efficacy. Amifostine is well tolerated in doses of 740 or 910 mg/m2. The most common side effects requiring treatment are transient hypotension, which responds to intravenous fluids, and nausea and vomiting, effectively treated with 5-HT3 antagonists and dexamethasone.