Human pharmacokinetics of WR-2721

Amifostine ameliorates bleomycin-induced murine pulmonary fibrosis via NAD+/SIRT1/AMPK pathway-mediated effects on mitochondrial function and cellular metabolism

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating chronic lung disease characterized by irreversible scarring of the lung parenchyma. Despite various interventions aimed at mitigating several different molecular aspects of the disease, only two drugs with limited clinical efficacy have so far been approved for IPF therapy.

OBJECTIVE

We investigated the therapeutic efficacy of amifostine, a detoxifying drug clinically used for radiation-caused cytotoxicity, in bleomycin-induced murine pulmonary fibrosis.

METHODS

C57BL6/J mice were intratracheally instilled with 3 U/kg of bleomycin. Three doses of amifostine (WR-2721, 200 mg/kg) were administered intraperitoneally on days 1, 3, and 5 after the bleomycin challenge. Bronchoalveolar lavage fluid (BALF) was collected on day 7 and day 21 for the assessment of lung inflammation, metabolites, and fibrotic injury. Human fibroblasts were treated in vitro with transforming growth factor beta 1 (TGF-β1), followed by amifostine (WR-1065, 1-4 µg/mL) treatment. The effects of TGF-β1 and amifostine on the mitochondrial production of reactive oxygen species (ROS) were assessed by live cell imaging of MitoSOX. Cellular metabolism was assessed by the extracellular acidification rate (ECAR), the oxygen consumption rate (OCR), and the concentrations of various energy-related metabolites as measured by mass spectrum (MS). Western blot analysis was performed to investigate the effect of amifostine on sirtuin 1 (SIRT1) and adenosine monophosphate activated kinase (AMPK).

RESULTS

Three doses of amifostine significantly attenuated lung inflammation and pulmonary fibrosis. Pretreatment and post-treatment of human fibroblast cells with amifostine blocked TGF-β1-induced mitochondrial ROS production and mitochondrial dysfunction in human fibroblast cells. Further, treatment of fibroblasts with TGF-β1 shifted energy metabolism away from mitochondrial oxidative phosphorylation (OXPHOS) and towards glycolysis, as observed by an altered metabolite profile including a decreased ratio of NAD + /NADH and increased lactate concentration. Treatment with amifostine significantly restored energy metabolism and activated SIRT1, which in turn activated AMPK. The activation of AMPK was required to mediate the effects of amifostine on mitochondrial homeostasis and pulmonary fibrosis. This study provides evidence that repurposing of the clinically used drug amifostine may have therapeutic applications for IPF treatment.

CONCLUSION

Amifostine inhibits bleomycin-induced pulmonary fibrosis by restoring mitochondrial function and cellular metabolism.

Identifying novel radioprotective drugs via salivary gland tissue chip screening

During head and neck cancer treatment, off-target ionizing radiation damage to the salivary glands commonly causes a permanent loss of secretory function. Due to the resulting decrease in saliva production, patients have trouble eating, speaking and are predisposed to oral infections and tooth decay. While the radioprotective antioxidant drug Amifostine is approved to prevent radiation-induced hyposalivation, it has intolerable side effects that limit its use, motivating the discovery of alternative therapeutics. To address this issue, we previously developed a salivary gland mimetic (SGm) tissue chip platform. Here, we leverage this SGm tissue chip for high-content drug discovery. First, we developed in-chip assays to quantify glutathione and cellular senescence (β-galactosidase), which are biomarkers of radiation damage, and we validated radioprotection using WR-1065, the active form of Amifostine. Following validation, we tested other reported radioprotective drugs, including, Edaravone, Tempol, N-acetylcysteine (NAC), Rapamycin, Ex-Rad, and Palifermin, confirming that all drugs but NAC and Ex-Rad exhibited robust radioprotection. Next, a Selleck Chemicals library of 438 FDA-approved drugs was screened for radioprotection. We discovered 25 hits, with most of the drugs identified with mechanisms of action other than antioxidant activity. Hits were down-selected using EC ₅₀ values and pharmacokinetics and pharmacodynamics data from the PubChem database leading to testing of Phenylbutazone (anti-inflammatory), Enoxacin (antibiotic), and Doripenem (antibiotic) for in vivo radioprotection in mice using retroductal injections. Results confirm that Phenylbutazone and Enoxacin exhibited equivalent radioprotection to Amifostine. This body of work demonstrates the development and validation of assays using a SGm tissue chip platform for high-content drug screening and the successful in vitro discovery and in vivo validation of novel radioprotective drugs with nonantioxidant primary indications pointing to possible, yet unknown novel mechanisms of radioprotection.

DMA, a Small Molecule, Increases Median Survival and Reduces Radiation-Induced Xerostomia via the Activation of the ERK1/2 Pathway in Oral Squamous Cell Carcinoma

Survival, recurrence, and xerostomia are considerable problems in the treatment of oral squamous carcinoma patients. In this study, we investigated the role of DMA (5-(4-methylpiperazin-1-yl)-2-[2′-(3,4-dimethoxyphenyl)5″benzimidazoyl]benzimidazole) as a salivary gland cytoprotectant in a patient-derived xenograft mouse model. A significant increase in saliva secretion was observed in the DMA-treated xenograft compared to radiation alone. Repeated doses of DMA with a high dose of radiation showed a synergistic effect on mice survival and reduced tumor growth. The mean survival rate of tumor-bearing mice was significantly enhanced. The increased number of Ki-67-stained cells in the spleen, intestine, and lungs compared to the tumor suggests DMA ablates the tumor but protects other organs. The expression of aquaporin-5 was restored in tumor-bearing mice injected with DMA before irradiation. The reduced expression of αvβ3 integrin and CD44 in DMA alone and DMA with radiation-treated mice suggests a reduced migration of cells and stemness of cancer cells. DMA along with radiation treatment results in the activation of the Ras/Raf/MEK/ERK pathway in the tumor, leading to apoptosis through caspase upregulation. In conclusion, DMA has strong potential for use as an adjuvant in radiotherapy in OSCC patients.

Akt1/NFκB signaling pathway activation by a small molecule DMA confers radioprotection to intestinal epithelium in xenograft model

Normal tissue protection and recovery of radiation-induced damage are of paramount importance for development of radioprotector. Radioprotector which selectively protects normal tissues over cancerous tissues improves the therapeutic window of radiation therapy. In the present study, small bisbenzimidazole molecule, DMA (5-(4-methylpiperazin-1-yl)-2-[2'-(3,4-dimethoxy-phenyl)-5'-benzimidazolyl]-benzimidazole) was evaluated for in vivo radioprotective effects to selectively protect normal tissue over tumor with underlying molecular mechanism. Administration of single DMA dose prior to radiation has enhanced survival of Balb/c mice against sublethal and supralethal total body irradiation. DMA ameliorated radiation-induced damage of normal tissues such as hematopoietic (HP) and gastrointestinal tract (GI) system. Oxidative stress marker Malondialdehyde level was decreased by DMA whereas it maintained endogenous antioxidant status by increasing the level of reduced glutathione, glutathione reductase, glutathione-s-transferase, superoxide dismutase and total thiol content in hepatic tissue of irradiated mice. Mechanistic studies revealed that DMA treatment prior to radiation leads to Akt1/NFκB signaling which reduced radiation-induced genomic instability in normal cells. However, these pathways were not activated in tumor tissues when subjected to DMA treatment in similar conditions. Abrogation of Akt1 and NFκB genes resulted in no radioprotection by DMA and enhanced apoptosis against radiation. Plasma half-life of DMA was 3.5h and 2.65h at oral and intravenous dose respectively and 90% clearance was observed in 16h. In conclusion, these data suggests that DMA has potential to be developed as a safe radioprotective agent for radiation countermeasures and an adjuvant in cancer therapy.

Radioprotector WR-2721 and mitigating peptidoglycan synergistically promote mouse survival through the amelioration of intestinal and bone marrow damage

The identification of an agent effective for the treatment of intestinal and bone marrow injury following radiation exposure remains a major issue in radiological medicine. In this study, we evaluated the therapeutic impact of single agent or combination treatments with 2-(3-aminopropylamino) ethylsulphanyl phosphonic acid (WR-2721) and peptidoglycan (PGN, a toll-like receptor 2 (TLR-2) agonist) on radiation-induced injury of the intestine and bone marrow in lethally irradiated male C57BL/6 mice. A dose of 3 mg of WR-2721 per mouse (167 mg/kg, intraperitoneally) was given 30 min before irradiation, and 30 μg of PGN per mouse (1.7 mg/kg) was injected intraperitoneally 24 h after 10 Gy irradiation. Bone marrow cluster of differentiation (CD)45(+) and CD34(+) markers of multiple haematopoietic lineages, number of granulocyte-erythroid-macrophage-megakaryocyte (GEMM) progenitor colonies, bone marrow histopathology, leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) expression in the intestines, xylose absorption and intestinal histopathology were all assessed at various time-points after irradiation. Furthermore, nuclear factor kappa B (NF-κB) p65 protein in the ileum was stained by immunofluorescent labelling. PGN-treated irradiated mice showed an increase in CD45(+)CD34(+) cells compared with untreated mice 1.25 days after 10 Gy ionizing radiation (IR) (P < 0.05). Furthermore, combined PGN and WR-2721 treatment had an obviously synergistic radio-protective effect in nucleated cells in the bone marrow, including GEMM progenitors and CD45(+)CD34(+) cells 4 days after 10 Gy IR. Single agent PGN or WR-2721 treatment after 10 Gy IR clearly increased Lgr5-positive pit cells (P < 0.05) and xylose absorption (P < 0.05). However only PGN and WR-2721 combination treatment markedly increased villus height (P < 0.05), number of crypts (P < 0.05) and whole-body weights after 10 Gy whole-body irradiation (WBI). The NF-κB p65 subunit was translocated to the nucleus, and phosphate-IκBα (Ser32/Ser36) was detected after stimulation with either PGN or WR-2721, which indicates that these two agents act synergistically through the activation of the NF-κB pathway. Administration of PGN in combination with WR-2721 was demonstrated to have a synergistic effect on the increase in haematopoietic cells and intestinal reconstitution, as well as improved survival in lethally irradiated mice, but resulted in some degree of an immune disorder.

Oxidative stress, redox regulation and diseases of cellular differentiation

BACKGROUND

Within cells, there is a narrow concentration threshold that governs whether reactive oxygen species (ROS) induce toxicity or act as second messengers.

SCOPE OF REVIEW

We discuss current understanding of how ROS arise, facilitate cell signaling, cause toxicities and disease related to abnormal cell differentiation and those (primarily) sulfur based pathways that provide nucleophilicity to offset these effects.

PRIMARY CONCLUSIONS

Cellular redox homeostasis mediates a plethora of cellular pathways that determine life and death events. For example, ROS intersect with GSH based enzyme pathways to influence cell differentiation, a process integral to normal hematopoiesis, but also affecting a number of diverse cell differentiation related human diseases. Recent attempts to manage such pathologies have focused on intervening in some of these pathways, with the consequence that differentiation therapy targeting redox homeostasis has provided a platform for drug discovery and development.

GENERAL SIGNIFICANCE

The balance between electrophilic oxidative stress and protective biomolecular nucleophiles predisposes the evolution of modern life forms. Imbalances of the two can produce aberrant redox homeostasis with resultant pathologies. Understanding the pathways involved provides opportunities to consider interventional strategies. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

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.

A phase I clinical and pharmacology study using amifostine as a radioprotector in dose-escalated whole liver radiation therapy

PURPOSE

Diffuse intrahepatic tumors are difficult to control. Whole-liver radiotherapy has been limited by toxicity, most notably radiation-induced liver disease. Amifostine is a prodrug free-radical scavenger that selectively protects normal tissues and, in a preclinical model of intrahepatic cancer, systemic amifostine reduced normal liver radiation damage without compromising tumor effect. We hypothesized that amifostine would permit escalation of whole-liver radiation dose to potentially control microscopic disease. We also aimed to characterize the pharmacokinetics of amifostine and its active metabolite WR-1065 to optimize timing of radiotherapy.

METHODS AND MATERIALS

We conducted a radiation dose-escalation trial for patients with diffuse, intrahepatic cancer treated with whole-liver radiation and intravenous amifostine. Radiation dose was assigned using the time-to-event continual reassessment method. A companion pharmacokinetic study was performed.

RESULTS

Twenty-three patients were treated, with a maximum dose of 40 Gy. Using a logistical regression model, compared with our previously treated patients, amifostine increased liver tolerance by 3.3 ± 1.1 Gy (p = 0.007) (approximately 10%) with similar response rates. Peak concentrations of WR-1065 were 25 μM with an elimination half-life of 1.5 h; these levels are consistent with radioprotective effects of amifostine in patients.

CONCLUSION

These findings demonstrate for the first time that amifostine is a normal liver radioprotector. They further suggest that it may be useful to combine amifostine with fractionated or stereotactic body radiation therapy for patients with focal intrahepatic cancer.

Subcutaneous compared with intravenous administration of amifostine in patients with head and neck cancer receiving radiotherapy: final results of the GORTEC2000-02 phase III randomized trial

PURPOSE

To compare compliance with and efficacy of intravenous (IV) and subcutaneous (SC) amifostine for the treatment of patients undergoing radiotherapy for head and neck cancer.

PATIENTS AND METHODS

Patients with newly diagnosed squamous cell carcinoma of the head and neck, who were eligible for radiotherapy and who were not receiving concurrent chemotherapy, were randomly assigned to receive either IV amifostine (200 mg/m(2) daily for 3 minutes, 15 to 30 minutes before irradiation) or SC amifostine (500 mg; two sites; 20 to 60 minutes before irradiation). The primary end point was late xerostomia at 1 year as indicated by unstimulated and stimulated salivary flow rates, a patient benefit questionnaire score, and Radiation Therapy Oncology Group (RTOG) late toxicity grade.

RESULTS

Results for IV (n = 143) versus SC (n = 148) administration were as follows. There was no significant difference in compliance (69% for IV v 71% for SC) in patients receiving a full dose of amifostine. Reasons for dose reduction were acute toxicity (25% for IV v 27% for SC; P = .51) and logistics (18% for IV v 9% for SC administration; P = .09). Acute toxicity differed significantly in terms of grade 1 to 2 hypotension (19% for IV v 8% for SC; P = .01), grade 1 to 2 skin rash (9% for IV v 21% for SC; P = .01), and local pain (0% for IV v 8% for SC; P = .003). The incidence of grade 2 or greater xerostomia was significantly higher for patients who received amifostine via SC administration (37% for IV v 62% for SC; P = .005) in the 127 patients (n = 67, IV; n = 60, SC) evaluable at 1 year but not at 2 or 3 years (36% for IV v 51% for SC administration; P = .19; 32% for IV v 41% for SC; P = .63). A generalized linear mixed-model analysis of all data revealed no significant difference in patient self-assessment of salivary function (P = .25), unstimulated or stimulated salivary flow rates (P = .054 and .82, respectively), or grade 2 or greater xerostomia (P = .23).

CONCLUSION

SC amifostine administration was not significantly superior to IV amifostine administration in terms of patient compliance or efficacy.

Clinical pharmacokinetics of amifostine and WR1065 in pediatric patients with medulloblastoma

PURPOSE

We evaluated the pharmacokinetics of amifostine and WR1065 in pediatric patients with newly diagnosed medulloblastoma to assess the influence of patient covariates, including demographics, clinical characteristics, and genetic polymorphisms, on amifostine and WR1065 pharmacokinetic parameters.

EXPERIMENTAL DESIGN

We assessed the pharmacokinetics of amifostine and WR1065 in 33 children who received amifostine (1-minute infusion, 600 mg/m(2)) just before the start of and 3 hours into a 6-hour cisplatin infusion. Serial blood samples were collected after doses 1 (0 hour) and 2 (3 hours) of course 1. Amifostine and WR1065 were quantitated by high performance liquid chromatography with electrochemical detection. A pharmacokinetic model was simultaneously fit to amifostine and WR1065 plasma or whole blood concentration-versus-time data. The influence of demographic, biochemical, and pharmacogenetic covariates on amifostine and WR1065 disposition was evaluated.

RESULTS

Body surface area was the primary size-based covariate for amifostine pharmacokinetics explaining 53% and 56% of interindividual variability in plasma and whole-blood amifostine clearance, respectively. The population-predicted values for amifostine clearance, volume, and apparent WR1065 clearance from the plasma data were 107 L/h/m(2), 5.53 L/m(2), and 30.6 L/h/m(2). The population-predicted values for amifostine clearance, volume, and apparent WR1065 clearance from whole blood data were 136 L/h/m(2), 7.23 L/m(2), and 12.5 L/h/m(2).

CONCLUSIONS

These results support using body surface area for calculating doses of amifostine in children. Similar to data in adults, amifostine and WR1065 are rapidly cleared from plasma and whole blood in children.

Randomized phase 2 study of subcutaneous amifostine versus epoetin-alpha given 3 times weekly during concurrent chemotherapy and hyperfractionated radiotherapy for limited-disease small cell lung cancer

BACKGROUND

The purpose of the current study was to investigate the role of amifostine and epoetin-alpha in reducing severe toxicities during concurrent chemo-hyperfractionated radiotherapy (CCRT) for limited disease small cell lung cancer (LD-SCLC).

METHODS

Seventy-six patients with LD-SCLC were enrolled. The treatment schedule was consisted of two 28-day cycles of cisplatin at a dose of 30 mg/m2 (Days 1 and 8) and irinotecan at a dose of 60 mg/m2 (Days 1, 8, and 15) followed by two 21-day cycles of cisplatin at a dose of 60 mg/m2 (Day 1) and etoposide at a dose of 100 mg/m2 (Days 1-3) with concurrent twice-daily thoracic radiotherapy for a total of 45 grays. Patients were randomly assigned at registration to either amifostine at a dose of 500 mg or epoetin-alpha at a dose of 10,000 IU subcutaneously 3 times weekly (n = 36 patients and 40 patients, respectively). Fifteen of 36 patients assigned to the amifostine arm did not receive amifostine because of a lack of supply.

RESULTS

Amifostine treatment was associated with higher febrile neutropenia (P = .003) and grade 2 or 3 nausea (according to the National Cancer Institute Common Toxicity Criteria [version 3.0]) (P = .03). It also demonstrated a trend toward higher grade 4 leukopenia (P = .05). Grade 3 esophagitis was reported in 30% of patients treated with amifostine and 9% of patients treated with epoetin-alpha (P = .059). Epoetin-alpha treatment was associated with less grade 2 or 3 anemia (P = .031) and lower decreases in hemoglobin level during CCRT (P = .016). The median survival times for both treatment arms were comparable (22.6 months in the amifostine arm vs 25.6 months in the epoetin-alpha arm; P = .447).

CONCLUSIONS

Although amifostine administered 3 times weekly during CCRT did not significantly reduce severe toxicities, epoetin-alpha was effective in preventing severe anemia during CCRT in patients with LD-SCLC. Other radioprotective strategies to minimize severe toxicities should be investigated.

Amifostine protective effect on cisplatin-treated rat testis

Cisplatin is a potent drug used in clinical oncology but causes spermatogenesis damage. Amifostine is a drug used against toxicity caused by ionizing irradiation and chemotherapeutic drugs. Since cisplatin provokes fertility and induces germ cell apoptosis and necrosis, we proposed to evaluate the amifostine cytoprotective action on testes of cisplatin-treated rats. Thirty-day-old prepubertal Wistar rats received a single cisplatin dose of 5 mg/kg and were killed after 3, 6, and 12 hr. The hematoxylin-eosin stained testicular sections were submitted to histological, morphometric, and stereological analysis. The terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling (TUNEL) method was used to label apoptotic cells. TUNEL-positive and TUNEL-negative germ cells with abnormal nuclear morphology (ANM) were scored. Significant alterations of greater part of the parameters occurred in the cisplatin-treated group (CE) compared to the group that received amifostine before the cisplatin-treatment (ACE); however, testicular weight and volume did not vary between these groups. Tubular diameter was reduced in CE in comparison to ACE rats, while interstitial tissue and lymphatic space volume and volume density were significantly higher in CE rats; interstitial testicular edema probably occurred in cisplatin-treated rats. CE rats showed important histological alterations, which were more accentuated than in ACE rats. The numerical densities of apoptotic germ cells and TUNEL-negative cells with ANM were lower in ACE than in CE rats. In conclusion, the amifostine previously administered to prepubertal rats reduced the testicular damage caused by cisplatin. We conclude that amifostine partially protected the rat seminiferous epithelium against cisplatin toxicity.

Should supplemental antioxidant administration be avoided during chemotherapy and radiation therapy?

Despite nearly two decades of research investigating the use of dietary antioxidant supplementation during conventional chemotherapy and radiation therapy, controversy remains about the efficacy and safety of this complementary treatment. Several randomized clinical trials have demonstrated that the concurrent administration of antioxidants with chemotherapy or radiation therapy reduces treatment-related side effects. Some data indicate that antioxidants may protect tumor cells as well as healthy cells from oxidative damage generated by radiation therapy and some chemotherapeutic agents. However, other data suggest that antioxidants can protect normal tissues from chemotherapy- or radiation-induced damage without decreasing tumor control. We review some of the data regarding the putative benefits and potential risks of antioxidant supplementation concurrent with cytotoxic therapy. On the basis of our review of the published randomized clinical trials, we conclude that the use of supplemental antioxidants during chemotherapy and radiation therapy should be discouraged because of the possibility of tumor protection and reduced survival.

Cytoprotective efficacy of amifostine against radiation- induced rectal toxicity: objective and subjective grading scales for radiomucositis

Curative radiation therapy of pelvic malignancies, frequently results in dose-limiting toxicities such as serous, mucoid, or more rarely, bloody diarrhea. Several studies have evaluated the cytoprotective effects of amifostine in preventing rectal mucositis associated with radiation treatment. We searched Medline for published comparative studies that evaluated the use of amifostine to reduce radiation-induced toxicity associated with pelvic irradiation. In ten studies there was an evidence-based cytoprotection (P<0.05) by amifostine. Although results are variable, current evidence suggests that amifostine may have a radioprotective effect in the rectal mucosa, particularly when administered intrarectally. Significant improvements were seen in both symptomatic and objective (rectosigmoidoscopy) end points. There is a need to conduct well-designed clinical trials with sufficient numbers of participants to confirm these findings together with a cost-benefit study. Objective measurements using rectosigmoidoscopy are superior to subjective measures such as WHO or RTOG/EORTC toxicity grading scales.

Amifostine: the first selective-target and broad-spectrum radioprotector

After several decades of preclinical and clinical research, the first approved radioprotective drug, amifostine, is being used in clinical practice. Amifostine has been shown to specifically protect normal tissues from damage caused by radiation and chemotherapy. An inactive prodrug, amifostine is converted to an active thiol by dephosphorylation by alkaline phosphatase in the normal endothelium. The hypovascularity and acidity of the tumor environment and the differential expression of alkaline phosphatase in normal and neoplastic tissues contribute to its cytoprotective selectivity. The cytoprotective mechanism of amifostine is complicated, involving free-radical scavenging, DNA protection and repair acceleration, and induction of cellular hypoxia. The U.S. Food and Drug Administration has approved the i.v. use of amifostine to reduce the cumulative renal toxicity associated with repeated administration of cisplatin in patients with advanced ovarian cancer and to reduce the incidence of moderate to severe xerostomia in patients undergoing postoperative radiation treatment for head and neck cancer, where the radiation port includes a substantial portion of the parotid glands. Nonetheless, amifostine has potential applications in many other oncologic settings. Novel schedules and routes of administration are under investigation and may further simplify the use of amifostine, reduce any undesired effects, and considerably broaden its applications. This review summarizes the clinical experience with amifostine and provides insight into future clinical directions.

Efficacy and safety of subcutaneous amifostine in minimizing radiation-induced toxicities in patients receiving combined-modality treatment for squamous cell carcinoma of the head and neck

PURPOSE

To report long-term data from a prospective trial of subcutaneous (s.c.) amifostine in patients who received chemoradiotherapy for squamous cell carcinoma of the head and neck (SCCHN).

METHODS AND MATERIALS

Patients >or=18 years of age with previously untreated Stage III/IV SCCHN received fractionated radiotherapy, 1.8-2.0 Gy/day, 5 days per week, to a total dose of 70-72 Gy, plus weekly paclitaxel (40 mg/m2) and carboplatin (100 mg/m2) administered intravenously (i.v.) for 6 weeks. All patients received 500 mg s.c. amifostine 30-60 min before radiotherapy with antihistamine and antiemetic prophylaxis.

RESULTS

Twenty patients were evaluable (median age, 55 years). The incidence of Grade 2 xerostomia was 42% and 29% at 12 and 18 months, respectively; there were no reports of Grade >or=3 xerostomia. Grade >or=3 mucositis occurred in 30% of patients, with median time to resolution of 12.5 weeks (range, 5-17 weeks). Survival estimates at 1 and 2 years were 95% and 71%, respectively. All patients experienced Grade 2 weight loss; 7 patients (35%) experienced Grade <or=2 nausea/vomiting. There were no reports of Grade >/=3 amifostine-related adverse events.

CONCLUSIONS

Subcutaneous amifostine was well tolerated by patients receiving chemoradiotherapy for SCCHN, with lower rates of nausea/vomiting than reported in trials with i.v. amifostine. Xerostomia and mucositis rates were similar to those reported in trials with i.v. amifostine.

Effect of Amifostine on Response Rates in Locally Advanced Non–Small-Cell Lung Cancer Patients Treated on Randomized Controlled Trials: A Meta-Analysis

PURPOSE

Amifostine can reduce the cytotoxic effects of chemotherapy and radiotherapy in patients with locally advanced non-small-cell lung cancer, but concerns remain regarding its possible tumor-protective effects. Studies with sufficient statistical power to address this question are lacking.

METHODS AND MATERIALS

We performed a meta-analysis of all published clinical trials involving locally advanced non-small-cell lung cancer patients treated with radiotherapy with or without chemotherapy, who had been randomized to treatment with amifostine vs. no amifostine or placebo. Random effects estimates of the relative risk of overall, partial, and complete response were obtained.

RESULTS

Seven randomized trials involving 601 patients were identified. Response rate data were available for six studies (552 patients). The pooled relative risk (RR) estimate was 1.07 (95% confidence interval, 0.97-1.18; p = 0.18), 1.21 (95% confidence interval, 0.83-1.78; p = 0.33), and 0.99 (95% confidence interval, 0.78-1.26; p = 0.95) for overall, complete, and partial response, respectively (a RR >1 indicates improvement in response with amifostine compared with the control arm). The results were similar after sensitivity analyses. No evidence was found of treatment effect heterogeneity across the studies.

CONCLUSIONS

Amifostine has no effect on tumor response in patients with locally advanced non-small-cell lung cancer treated with radiotherapy with or without chemotherapy.

Radiobiologic Modeling of Cytoprotection Effects in Radiotherapy

PURPOSE

To investigate the potential for mathematical modeling of the normal tissue-sparing effects of cytoprotective agents used in conjunction with radiotherapy and chemotherapy.

METHODS AND MATERIALS

The linear quadratic model was modified to include a "cytoprotection factor," in two alternative ways. The published results on the incidence of treatment-related oral mucositis in patients treated for head-and-neck carcinoma using radiotherapy alone or combined with chemotherapy were assessed against the model to determine the likely values of the cytoprotection factor required to confer a reasonable degree of cytoprotection.

RESULTS

In both of the model alternatives considered, a cytoprotection factor value of < or = 0.85 was required for a clinically detectable degree of cytoprotection to be realized. A cytoprotection factor value of 0.85 would mean that the radiation sensitivity coefficients would be effectively reduced by 15% on account of the action of the cytoprotector.

CONCLUSION

The incorporation of a cytoprotection factor into an existing linear quadratic method would allow a quantitative assessment of cytoprotection and could be useful in the design of future clinical studies.

Maximizing the Delivery of Intraperitoneal Therapy While Minimizing Drug Toxicity and Maintaining Quality of Life

This decade has witnessed three large randomized trials (SWOG 8501/GOG 104, GOG 114, and GOG 172) clearly showing the advantages of intraperitoneal (IP) chemotherapy over systemic/intravenous therapy in treating selected patients with advanced stage ovarian cancer. Despite showing an impressive increase in median progression-free survival and median overall survival, complications in IP chemotherapy delivery and drug-related toxicities reported in these studies have hindered widespread acceptance and implementation of first-line IP therapy. Some of these complications and drug-related toxicities are treatment-limiting and need special attention. Success of IP therapy as a first-line choice of treatment is dependent upon ideal patient selection, effective delivery of appropriate doses of chemotherapy agents to the tumor site, and efficient management of complications. With proper orientation and instruction in IP catheter placement and patient management, these obstacles can be overcome, allowing for successful administration of IP therapies. This review article discusses clinical approaches to maximize the delivery of IP therapy while minimizing catheter complications. Mitigating drug toxicities with the use of cytoprotectants such as amifostine and preventing infection with the use of agents, such as amifostine and pegfilgrastim, are discussed in detail.

Phase II multicenter randomized study of amifostine for prevention of acute radiation rectal toxicity: topical intrarectal versus subcutaneous application

PURPOSE

To investigate the cytoprotective effect of subcutaneous vs. intrarectal administration of amifostine against acute radiation toxicity.

METHODS AND MATERIALS

Patients were randomized to receive amifostine either intrarectally (Group A, n = 27) or a 500-mg flat dose subcutaneously (Group B, n = 26) before irradiation. Therapy was delivered using a four-field technique with three-dimensional conformal planning. In Group A, 1,500 mg of amifostine was administered intrarectally as an aqueous solution in 40 mL of enema. Two different toxicity scales were used: the European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group (RTOG) rectal and urologic toxicity criteria and the Subjective-RectoSigmoid scale based on the endoscopic terminology of the World Organization for Digestive Endoscopy. Objective measurements with rectosigmoidoscopy were performed at baseline and 1-2 days after radiotherapy completion. The area under the curve for the time course of mucositis (RTOG criteria) during irradiation represented the mucositis index.

RESULTS

Intrarectal amifostine was feasible and well tolerated without any systemic or local side effects. According to the RTOG toxicity scale, Group A had superior results with a significantly lower incidence of Grades I-II rectal radiation morbidity (11% vs. 42%, p = 0.04) but inferior results concerning urinary toxicity (48% vs. 15%, p = 0.03). The mean rectal mucositis index and Subjective-RectoSigmoid score were significantly lower in Group A (0.44 vs. 2.45 [p = 0.015] and 3.9 vs. 6.0 [p = 0.01], respectively), and the mean urinary mucositis index was lower in Group B (2.39 vs. 0.34, p < 0.028).

CONCLUSIONS

Intrarectal administration of amifostine (1,500 mg) seemed to have a cytoprotective efficacy in acute radiation rectal mucositis but was inferior to subcutaneous administration in terms of urinary toxicity. Additional randomized studies are needed for definitive decisions concerning the cytoprotection of pelvic irradiated areas.

Impact on cytoprotective efficacy of intermediate interval between amifostine administration and radiotherapy: a retrospective analysis

PURPOSE

To evaluate the cytoprotective impact of the interval between amifostine administration and radiotherapy (RT).

METHODS AND MATERIALS

In a nonrandomized study, we reviewed the records of 177 patients with tumors localized in the pelvis (prostate, bladder, or gynecologic cancer), upper abdomen (pancreas, stomach, kidney), thorax (lung and breast cancer), head and neck (nasopharynx), soft tissue (sarcomas), and central nervous system. The patient records were stratified according to whether the patients had undergone RT either 25-40 min (Group 1, 96 subjects) or 10-15 min (Group 2, 81 subjects) after i.v. amifostine administration. The mean toxicity score was the mean value of recorded acute radiation toxicity. The mean interruption time was the mean value of the recorded interruption time due to radiation toxicity.

RESULTS

A significantly reduced severity of symptoms related to oral (p = 0.023), esophageal (p = 0.05) and rectal (p = 0.015) mucosa was noted in Group 2. A statistically significant reduction in the mean toxicity score (p <0.001) and mean interruption time (p = 0.001) was observed in Group 2 vs. Group 1. In terms of the incidence of radiation-induced dermatitis and alopecia, multivariate logistic analysis revealed only the total dose (p = 0.018) and the amifostine-RT interval (p = 0.002) as independent factors.

CONCLUSION

A significantly better cytoprotective effect of amifostine against radiation-induced mucositis, dermatitis, and alopecia was noted if RT was administered no later than 15 min after i.v. amifostine infusion. The results presented here need additional investigation with randomized prospective trials.

p53 protein regulates the effects of amifostine on apoptosis, cell cycle progression, and cytoprotection

To determine the role of p53 protein on the cellular effects of amifostine, we used molecularly engineered HCT116 colon cancer cells in which the p53 gene was inactivated by targeted homologous recombination or p53 protein was degraded by high-level expression of papillomavirus E6 protein. Amifostine induced a G1 arrest and protected against paclitaxel toxicity in p53-proficient but not in p53-deficient cells. In the absence of p53 protein, amifostine enhanced the cytotoxicity of paclitaxel. In addition, treatment of HCT116 cells with amifostine alone resulted in apoptotic cell death. Compared with p53-deficient cells, p53-proficient cells exhibited low-level resistance to amifostine-induced apoptosis. Amifostine induced the expression of p53 protein in p53-proficient cells and the expression of p21 protein in both p53-proficient and -deficient cells. These findings indicate that amifostine-induced G1 arrest and cytoprotection are mediated via a pathway that is dependent on p53 protein and that amifostine-induced expression of p21 protein is not sufficient to sustain a G1 arrest or to mediate cytoprotection. In addition, these findings identify p53 protein as a mechanism of resistance to amifostine-induced apoptosis.British

Regional pharmacokinetics of amifostine in anesthetized dogs: role of the liver, gastrointestinal tract, lungs, and kidneys

Amifostine is a prodrug in which selectivity is largely determined by the preferential formation and uptake of its cytoprotective metabolite, WR-1065, in normal tissues as a result of differences in membrane-bound alkaline phosphatase activity. In this study, we characterized the sites and extent of organ-specific activation by the liver, gastrointestinal tract, lungs, and kidneys after systemic administrations of amifostine. A total of 10 dogs were infused via the cephalic vein using sequential dose rates of drug at 0.125, 0.500, and 1.00 micro mol/min/kg. Infusion of each dose rate lasted 2 h, at which time steady-state plasma concentrations were obtained (i.e., portal vein, carotid artery, hepatic vein, pulmonary artery, and renal vein). The hepatic arterial, portal venous, and renal arterial blood flows, and cardiac output, were measured. The hepatic and splanchnic extraction of amifostine remained high at 90%, whereas gastrointestinal extraction decreased from 43 to 12 to 15% with increasing dose. Pulmonary extraction of amifostine was low at 7%, whereas renal extraction was intermediate at 57%. Because blood flow measurements were relatively constant during the drug infusions, clearance parameters paralleled that of organ extraction. As a result, saturability was observed in the gastrointestinal blood clearance (i.e., from 9.8 to 2.8-3.3 ml/min/kg) and total body plasma clearance of amifostine (i.e., from 52.6 to about 37.3 ml/min/kg), as the doses increased. Due to the drug's high activation in liver, these findings suggest that amifostine may offer good protection of this organ against the toxicities of chemotherapy and radiation.

New liquid chromatographic assay with electrochemical detection for the measurement of amifostine and WR1065

A high-performance liquid chromatographic method (HPLC) was developed for the analysis of the radio- and chemo-protectant, amifostine and its active metabolite-WR1065 in deproteinized human whole blood and plasma. The two compounds were quantified by measuring WR1065 after two different sample pretreatment procedures. During these procedures, amifostine was quantitatively converted into WR1065, by incubating the sample at 37 degrees C for 4 h at pH<1.0. The resulting amounts of WR1065 were determined by HPLC with coulometric detection (analytical cell: E(1)=200 mV and E(2)=600 mV; guard cell: E(G)=650 mV). The WR1065 standard curve ranged from 0.37 to 50.37 microM. The lower limit of quantitation of WR1065 was 0.25 microM. The within- and between-day precisions were < or = 4.3% and < or = 6.0% for amifostine, < or = 4.4% and < or = 3.8% for WR1065, respectively. The within- and between-day accuracy ranged from 95.4 to 97.7% and 95.4 to 97.8% for amifostine, and from 97.1 to 101.7% and 97.2 to 99.7% for WR1065, respectively. This method minimizes WR1065 loss during sample preparation, and allows for rapid analysis of both compounds on one system. Furthermore, the application of a coulometric electrode is more efficient and requires less maintenance than previously published methods for the two compounds.

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.

New dosing regimens for amifostine: a pilot study to compare the relative bioavailability of oral and subcutaneous administration with intravenous infusion

A phase I clinical trial was conducted to assess thefeasibility of a more convenient and safe dosing regime for the cytoprotective drug amifostine. Two alternative routes of administration, oral and subcutaneous (s.q.), each with a dose of 500 mg, were compared to a 7.5-minute intravenous (i.v.) infusion, with a dose of 200 mg/m2, in normal, healthy volunteers (N = 12). Bioavailability of amifostine (parent drug) and its pharmacologically active metabolite, WR-1065, was evaluated by comparing the area under the concentration-time curve (AUC) derived from HPLC analysis of amifostine and both protein-free and protein-bound WR-1065 in all three routes of administration. Results showed that SQ (but not oral) administration of amifostine could provide a more effective dosing regimen, in terms of both a reasonable AUC for the bound form of WR-1065 and decreased toxicity, compared to i.v. delivery. These data suggest that the protein-bound form of WR-1065 plays an important role in contributing to the bioavailability of this clinically useful cytoprotective drug.

Phase I trial of a twice-daily regimen of amifostine with ifosfamide, carboplatin, and etoposide chemotherapy in children with refractory carcinoma

BACKGROUND

Amifostine protects normal tissues against chemotherapy and radiation-induced toxicity without loss of antitumor effects. Evidence suggests that multiple daily doses of amifostine may improve its cytoprotective effects. The purpose of this study was to assess the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of twice-daily doses of amifostine with ifosfamide, carboplatin, and etoposide (ICE) chemotherapy for children with refractory malignancies and to determine the pharmacokinetic properties of amifostine, WR-1065, and the disulfide metabolites of amifostine.

METHODS

Patients with refractory malignancies were treated with amifostine 15 minutes before and 2 hours after chemotherapy with ifosfamide (3 g/m(2) per dose on Days 1 and 2) and carboplatin (635 mg/m(2) on Day 3). Etoposide was administered on Days 1 and 2 (150 mg/m(2)). The starting dose of amifostine was 740 mg/m(2). Pharmacokinetic studies were performed after the first dose of amifostine.

RESULTS

Twelve patients received 23 courses of ICE and amifostine. Dose-limiting toxicities for amifostine at 740 mg/m(2) were somnolence and anxiety. The other Grade 3 and 4 toxicities included asymptomatic, reversible hypocalcemia, vomiting, and reversible hypotension. At a dose of 600 mg/m(2), amifostine was well tolerated. Hypocalcemia, due to rapid, transient suppression of parathyroid hormone production, required close monitoring and aggressive intravenous calcium supplementation. Pharmacokinetic studies revealed high interpatient variability with rapid plasma clearance of amifostine and WR-1065. The median elimination half-life of amifostine (9.3 minutes) and WR-1065 (15 minutes) was much shorter than the disulfide metabolites (74.4 minutes).

CONCLUSIONS

The recommended pediatric dose of amifostine for a twice-daily regimen is 600 mg/m(2) per dose (1200 mg/m(2)/day) with DLTs of anxiety and somnolence, lower than the previously recommended single dose of 1650 mg/m(2).

Selective radioprotection of hepatocytes by systemic and portal vein infusions of amifostine in a rat liver tumor model

PURPOSE

The tolerance of the liver to radiation is too low to permit an effective dose to be delivered to patients who have diffuse intrahepatic cancer. In this study we evaluated whether systemic or portal venous administration of the aminothiol compound, amifostine, could protect the normal liver from the effects of ionizing radiation without compromising tumor cell kill in a rat liver tumor model.

METHODS AND MATERIALS

Rats implanted with liver tumors were infused with 200 mg/kg amifostine over 15 min via the femoral or portal vein. The livers were irradiated with a single 6-Gy fraction 15-20 min after the termination of amifostine infusion. Protection of the liver was assessed by an in vitro hepatocyte micronucleus assay and tumor protection by an in vivo-in vitro clonogenic survival assay. Tissue levels of the active metabolite, free WR-1065, were determined in the tumor and in the normal liver using a specific HPLC assay with electrochemical detection.

RESULTS

After a 6-Gy fraction, the frequency of hepatocyte micronuclei after administration of saline, systemic amifostine, and portal venous amifostine was 18.7+/-1%, 6.8+/-1%, and 9.9+/-2%, respectively, corresponding to a radiation equivalent effect of 6 Gy +/- 0.5, 1.8 Gy +/- 0.3, and 2.5 Gy +/- 1.3, respectively. Both amifostine conditions showed considerably less radiation effect than saline-treated controls (p < 0.01); the two amifostine conditions did not differ (p = 0.3). The surviving fraction of tumor cells was not affected by amifostine treatment and was 0.03+/-0.02 and 0.05+/-0.03 for systemic and portal venous delivery and 0.06+/-0.02 for control animals (ANOVA analysis showed no significant difference of the means p = 0.34). Portal venous delivery produced significantly less WR-1065 in the tumor compared to systemic administration (54 microM +/- 36 vs. 343 microM +/- 88, respectively, p = 0.03).

CONCLUSIONS

Both systemic and portal venous administration of amifostine effectively protect hepatocytes from ionizing radiation without compromising tumor cell kill in a clinically relevant animal model. These findings suggest that amifostine may be a selective normal tissue radioprotectant in liver cancer and that regional/portal infusions may be preferable to systemic dosing.

Amifostine: chemotherapeutic and radiotherapeutic protective effects

Amifostine (Ethyoltrade mark, Alza Pharmaceuticals) is an inorganic thiophosphate cytoprotective agent known chemically as ethanethiol, 2-[3- aminopropyl)amino]dihydrogen phosphate. It is a prodrug of free thiol (WR-1065) that may act as a scavenger of free radicals generated in tissues exposed to cytotoxic drugs and binds to reactive metabolites of such drugs. Amifostine was originally developed as a radioprotective agent in a classified nuclear warfare project. Following declassification of the project it was evaluated as a cytoprotective agent against toxicity of the alkylating drugs and cisplatin. Differences in the alkaline phosphatase concentration of normal versus tumour tissues can result in greater conversion of amifostine in normal tissues. Inside the cell, WR-1065 provides an alternative target to DNA and RNA for the reactive molecules of alkylating or platinum agents and acts as a potent scavenger of the oxygen free radicals induced by ionizing radiation and some chemotherapy agents. Preclinical animal studies have demonstrated that the administration of amifostine protects against a variety of chemotherapy-related toxicities including cisplatin-induced nephrotoxicity, cisplatin-induced neurotoxicity, cyclophosphamide- and bleomycin-induced pulmonary toxicity and the cytotoxicities (including cardiotoxicity) induced by doxorubicin and related chemotherapeutic agents. Amifostine has been shown to protect a variety of animal species from lethal doses of radiation. Amifostine gives haematological protection from cyclophosphamide, carboplatin, mitomycin C, fotemustine and radiotherapy; renal and peripheral nerve protection from cisplatin; mucosa, skin and salivary gland protection from radiotherapy. Multiple Phase I studies were carried out with amifostine in combination with chemotherapy for various neoplasms. Appropriate doses of amifostine were found to be 740 - 910 mg/m(2) in single-dose regimens and 340 mg/m(2) in multiple-dose regimens. In radioprotection, doses are generally 200 - 350 mg/m(2). For all these characteristics, amifostine has been recently approved and suggested in ASCO clinical practice guidelines as a radioprotector for head and neck cancer treatment and supportive agent during cisplatin-based chemotherapy, in lymphomas and solid tumours. Moreover, its spectrum of possible applications is enlarging. As data have been provided indicating that amifostine stimulates haematopoiesis, it has been employed with intriguing results in the treatment of myelodysplastic syndromes (MDS).

Anticancer drug-induced kidney disorders

Nephrotoxicity is an inherent adverse effect of certain anticancer drugs. Renal dysfunction can be categorised as prerenal uraemia, intrinsic damage or postrenal uraemia according to the underlying pathophysiological process. Renal hypoperfusion promulgates prerenal uraemia. Intrinsic renal damage results from prolonged hypoperfusion, exposure to exogenous or endogenous nephrotoxins, renotubular precipitation of xenobiotics or endogenous compounds, renovascular obstruction, glomerular disease, renal microvascular damage or disease, and tubulointerstitial damage or disease. Postrenal uraemia is a consequence of clinically significant urinary tract obstruction. Clinical signs of nephrotoxicity and methods used to assess renal function are discussed. Mechanisms of chemotherapy-induced renal dysfunction generally include damage to vasculature or structures of the kidneys, haemolytic uraemic syndrome and prerenal perfusion deficits. Patients with cancer are frequently at risk of renal impairment secondary to disease-related and iatrogenic causes. This article reviews the incidence, presentation, prevention and management of anticancer drug-induced renal dysfunction. Dose-related nephrotoxicity subsequent to administration of certain chloroethylnitrosourea compounds (carmustine, semustine and streptozocin) is commonly heralded by increased serum creatinine levels, uraemia and proteinuria. Additional signs of streptozocin-induced nephrotoxicity include hypophosphataemia, hypokalaemia, hypouricaemia, renal tubular acidosis, glucosuria, aceturia and aminoaciduria. Cisplatin and carboplatin cause dose-related renal dysfunction. In addition to increased serum creatinine levels and uraemia, electrolyte abnormalities, such as hypomagnesaemia and hypokalaemia, are commonly reported adverse effects. Rarely, cisplatin has been implicated as the underlying cause of haemolytic uraemic syndrome. Pharmaceutical antidotes to cisplatin-induced nephrotoxicity include amifostine, sodium thiosulfate and diethyldithiocarbamate. Dose- and age-related proximal tubular damage is an adverse effect of ifosfamide. In addition to renal wasting of electrolytes, glucose and amino acids, Fanconi syndrome, rickets and osteomalacia have occurred with ifosfamide treatment. High dose azacitidine causes renal dysfunction manifested by tubular acidosis, polyuria and increased urinary excretion of electrolytes, glucose and amino acids. Haemolytic uraemia is a rare adverse effect of gemcitabine. Methotrexate can cause increased serum creatinine levels, uraemia and haematuria. Acute renal failure is reported following administration of high dose methotrexate. Urinary alkalisation and hydration confer protection against methotrexate-induced renal dysfunction. Dose-related nephrotoxicity, including acute renal failure, are reported subsequent to treatment with pentostatin and diaziquone. Acute renal failure is a rare adverse effect of treatment with interferon-alpha. Haemolytic uraemic syndrome occurs with mitomycin administration. A mortality rate of 50 to 100% is reported in patients developing mitomycin-induced haemolytic uraemic syndrome. Capillary leak syndrome occurring with aldesleukin therapy can cause renal dysfunction. Infusion-related hypotension during infusion of high dose carmustine can precipitate renal dysfunction.

Pilot trial of cytoprotection with amifostine given with high-dose chemotherapy and autologous peripheral blood stem cell transplantation

In an attempt to limit toxicities associated with dose-intensive therapy used for transplant regimens, we performed a pilot study using amifostine with high-dose busulfan (12 mg/kg), melphalan (100 mg/m2), and thiotepa (500 mg/m2) in 21 patients with a variety of malignancies. After 3 days of oral busulfan, amifostine was given at 910 mg/m2 IV for 10 minutes, preceding the infusion of each of 2 doses of melphalan and thiotepa given for 4 days. Antiemetic premedication for amifostine was given to all patients. The median patient age was 50 years (range: 32-65 years). Twenty-one patients received 82 separate amifostine infusions. One patient discontinued amifostine after the second dose because of severe nausea and emesis, and two infusions were temporarily held secondary to hypotension. Of these 82 cycles, there was a total of 37 episodes of nausea/vomiting, 28 episodes of sneezing, 11 episodes of flushing, and 1 episode of oral paresthesia. Systolic blood pressure and mean arterial pressure decreased by a mean of 8.4 mm Hg and 5.0 mm Hg, respectively. In general, the infusion was well tolerated. Patients were observed until discharge home (N = 15), until initiation of an additional tandem transplant procedure (N = 4), or until death (N = 2). All twenty-one patients experienced nonhematologic toxicities grade II or greater. Grade II toxicities included mucositis (N = 21), gastrointestinal (N = 3), skin (N = 1), and liver (N = 1), and grade III toxicities included liver (N = 1). Mucositis was also scored according to a detailed toxicity assessment. Mucositis did not appear to be improved with amifostine when compared with a control group of patients not receiving amifostine. Renal dysfunction after transplantation was decreased in the amifostine group, whereas there was no significant effect on posttransplant hepatic dysfunction. Although these data demonstrate the feasibility of delivering parenteral amifostine in conjunction with dose-intensive chemotherapy and autologous peripheral blood stem cell transplantation, there was no evidence of a significant reduction in nonmarrow toxicities.

Subcutaneous administration of amifostine during fractionated radiotherapy: a randomized phase II study

PURPOSE

Amifostine (WR-2721) is an important cytoprotective agent. Although intravenous administration is the standard route, pharmacokinetic studies have shown acceptable plasma levels of the active metabolite of amifostine (WR-1605) after subcutaneous administration. The subcutaneous route, due to its simplicity, presents multiple advantages over the intravenous route when amifostine is used during fractionated radiotherapy.

PATIENTS AND METHODS

Sixty patients with thoracic, 40 with head and neck, and 40 with pelvic tumors who were undergoing radical radiotherapy were enrolled onto a randomized phase II trial to assess the feasibility, tolerance, and cytoprotective efficacy of amifostine administered subcutaneously. A flat dose of amifostine 500 mg, diluted in 2.5 mL of normal saline, was injected subcutaneously 20 minutes before each radiotherapy fraction.

RESULTS

The subcutaneous amifostine regimen was well tolerated by 85% of patients. In approximately 5% of patients, amifostine therapy was interrupted due to cumulative asthenia, and in 10%, due to a fever/rash reaction. Hypotension was never noted, whereas nausea was frequent. A significant reduction of pharyngeal, esophageal, and rectal mucositis was noted in the amifostine arm (P <.04). The delays in radiotherapy because of grade 3 mucositis were significantly longer in the group of patients treated with radiotherapy alone (P <.04). Amifostine significantly reduced the incidence of acute perineal skin and bladder toxicity (P <.0006).

CONCLUSION

Subcutaneous administration of amifostine is well tolerated, effectively reduces radiotherapy's early toxicity, and prevents delays in radiotherapy. The subcutaneous route is much simpler and saves time compared with the intravenous route of administration and can be safely and effectively applied in the daily, busy radiotherapy practice.

Randomized phase II study of high-dose paclitaxel with or without amifostine in patients with metastatic breast cancer

PURPOSE

To determine whether the neurotoxicity of paclitaxel 250 mg/m(2) given over 3 hours every 3 weeks could be reduced by pretreatment with amifostine 910 mg/m(2). Secondary objectives included comparing myelosuppression, myalgias, and response rates of the two groups.

PATIENTS AND METHODS

Forty women with metastatic breast cancer were randomized to receive either paclitaxel alone (arm 1) or paclitaxel preceded by amifostine (arm 2). All were assessable for toxicity, and 37 were assessable for response. At baseline and after each cycle, all patients completed questionnaires for neurologic symptoms and had standardized neurologic examinations, including objective assessments of power and vibration sense. In addition, standard follow-up assessments for other toxicities and tumor response were undertaken. Changes from baseline after courses 1, 2, and 3 were assessed. The sample size was sufficient to detect a 50% improvement in the expected determination in sensory change.

RESULTS

There were no differences observed in any of the measures of neurotoxicity. Other toxicity was similar in arms 1 and 2, including hair loss (95% v 90%), neurosensory changes (100% v 100%), fatigue/lethargy (85% v 90%), myalgia (95% v 90%), and grade 4 neutropenia (47% v 60%). Nausea, vomiting, dizziness, hypotension, and sneezing were more common in the amifostine arm. Response rates (22.2% v 36.8%) and paclitaxel pharmacokinetics were not significantly different.

CONCLUSION

There was no protection from paclitaxel-related neurotoxicity or hematologic toxicity in this study. These results suggest that the mechanism of action of paclitaxel-related toxic effects is not amenable to the cytoprotective action of amifostine.

American Society of Clinical Oncology clinical practice guidelines for the use of chemotherapy and radiotherapy protectants

PURPOSE

Because toxicities associated with chemotherapy and radiotherapy can adversely affect short- and long-term patient quality of life, can limit the dose and duration of treatment, and may be life-threatening, specific agents designed to ameliorate or eliminate certain chemotherapy and radiotherapy toxicities have been developed. Variability in interpretation of the available data pertaining to the efficacy of the three United States Food and Drug Administration-approved agents that have potential chemotherapy- and radiotherapy-protectant activity-dexrazoxane, mesna, and amifostine-and questions about the role of these protectant agents in cancer care led to concern about the appropriate use of these agents. The American Society of Clinical Oncology sought to establish evidence-based, clinical practice guidelines for the use of dexrazoxane, mesna, and amifostine in patients who are not enrolled on clinical treatment trials.

METHODS

A multidisciplinary Expert Panel reviewed the clinical data regarding the activity of dexrazoxane, mesna, and amifostine. A computerized literature search was performed using MEDLINE. In addition to reports collected by individual Panel members, all articles published in the English-speaking literature from June 1997 through December 1998 were collected for review by the Panel chairpersons, and appropriate articles were distributed to the entire Panel for review. Guidelines for use, levels of evidence, and grades of recommendation were reviewed and approved by the Panel. Outcomes considered in evaluating the benefit of a chemotherapy- or radiotherapy-protectant agent included amelioration of short- and long-term chemotherapy- or radiotherapy-related toxicities, risk of tumor protection by the agent, toxicity of the protectant agent itself, quality of life, and economic impact. To the extent that these data were available, the Panel placed the greatest value on lesser toxicity that did not carry a concomitant risk of tumor protection.

RESULTS AND CONCLUSION

Mesna: (1) Mesna, dosed as detailed in these guidelines, is recommended to decrease the incidence of standard-dose ifosfamide-associated urothelial toxicity. (2) There is insufficient evidence on which to base a guideline for the use of mesna to prevent urothelial toxicity with ifosfamide doses that exceed 2.5 g/m(2)/d. (3) Either mesna or forced saline diuresis is recommended to decrease the incidence of urothelial toxicity associated with high-dose cyclophosphamide use in the stem-cell transplantation setting. Dexrazoxane: (1) The use of dexrazoxane is not routinely recommended for patients with metastatic breast cancer who receive initial doxorubicin-based chemotherapy. (2) The use of dexrazoxane may be considered for patients with metastatic breast cancer who have received a cumulative dosage of 300 mg/m(2) or greater of doxorubicin in the metastatic setting and who may benefit from continued doxorubicin-containing therapy. (3) The use of dexrazoxane in the adjuvant setting is not recommended outside of a clinical trial. (4) The use of dexrazoxane can be considered in adult patients who have received more than 300 mg/m(2) of doxorubicin-based therapy for tumors other than breast cancer, although caution should be used in settings in which doxorubicin-based therapy has been shown to improve survival because of concerns of tumor protection by dexrazoxane. (5) There is insufficient evidence to make a guideline for the use of dexrazoxane in the treatment of pediatric malignancies, with epirubicin-based regimens, or with high-dose anthracycline-containing regimens. Similarly, there is insufficient evidence on which to base a guideline for the use of dexrazoxane in patients with cardiac risk factors or underlying cardiac disease. (6) Patients receiving dexrazoxane should continue to be monitored for cardiac toxicity. Amifostine: (1) Amifostine may be considered for the reduction of nephrotoxicity in patients receiving cisplatin-based chemoth

The sulfhydryl containing compounds WR-2721 and glutathione as radio- and chemoprotective agents. A review, indications for use and prospects

Radio- and chemotherapy for the treatment of malignancies are often associated with significant toxicity. One approach to reduce the toxicity is the concomitant treatment with chemoprotective agents. This article reviews two sulfhydryl compounds, namely the agent WR-2721 (amifostine), a compound recently registered for use in human in many countries, and the natural occurring compound glutathione (GSH). GSH is not registered as a chemoprotective agent. WR-2721 is an aminothiol prodrug and has to be converted to the active compound WR-1065 by membrane-bound alkaline phosphatase. WR-1065 and GSH both act as naturally occurring thiols. No protective effect on the tumour has been found when these compounds are administered intravenously. There is even in vitro evidence for an increased anti-tumour effect with mafosfamide after pretreatment with WR-2721, and in vivo after treatment with carboplatin and paclitaxel. Randomized clinical studies have shown that WR-2721 and GSH decrease cisplatin-induced nephrotoxicity and that WR-2721 reduces radiation radiotherapy-induced toxicity. Side-effects associated with WR-2721 are nausea, vomiting and hypotension, GSH has no side-effects. An exact role of WR-2721 and GSH as chemoprotectors is not yet completely clear. Future studies should examine the protective effect of these drugs on mucositis, cardiac toxicity, neuro- and ototoxicity, the development of secondary neoplasms and their effect on quality of life.

Pharmacokinetics of amifostine and its metabolites in patients

The pharmacokinetics of the cytoprotective agent amifostine (EthyolR; WR 2721) and its main metabolites (WR 1065 and the disulphides) were studied in patients participating in two phase I trials concerning carboplatin or cisplatin in combination with amifostine. Patients were treated with a single dose or three doses of amifostine (740 or 910 mg/m2). The single or first dose was given as a 15 min i.v. infusion just before administration of the chemotherapeutic agent. The additional two infusions were administered 2 and 4 h thereafter. Amifostine was rapidly cleared from the plasma, due to, at least in part, the fast conversion into WR 1065. A biphasic decrease with a final half-life of 0.8 h was observed. The active metabolite WR 1065 was cleared from the plasma with a final half-life of 7.3 +/- 3.6 h. The short initial half-life of WR 1065 can be explained by its fast uptake in tissues and the formation of disulphides. The disulphides were cleared with a final half-life of 8.4-13.4 h and were detectable for at least 24 h after treatment. They may serve as an exchangeable pool of WR 1065. The amifostine peak values at the end of each 15 min infusion did not accumulate in the multiple dosing schedule. For WR 1065 a trend towards an increase in the peak levels was observed [C1,max: 47.5 +/- 11.9 microM, C2,max: 79.0 +/- 13.2 microM, C3,max: 84.8 +/- 15.1 microM, (n = 6)], whereas a trend towards a small decrease was observed for the peak levels of the disulphides [C1,max: 184.2 +/- 12.6 microM, C2,max: 175.0 +/- 23.7 microM, C3,max: 166.0 +/- 17.2 microM, (n = 6)]. This latter finding might suggest a saturation of the disulphide formation or a change in the uptake or elimination of WR 1065, which would result in higher WR 1065 levels in plasma and tissues, after multiple doses of amifostine.

The preclinical basis for broad-spectrum selective cytoprotection of normal tissues from cytotoxic therapies by amifostine (Ethyol)

Administered prior to cytotoxic chemotherapy or radiation, the aminothiol amifostine provides broad-spectrum cytoprotection of various normal tissues without attenuating antitumour response. The basis for the selectivity of action resides in the anabolism of amifostine at the normal tissue site by membrane-bound alkaline phosphatase. Dephosphorylation to the free thiol, WR-1065, is followed by rapid uptake into normal tissues by a carrier mediated, facilitated diffusion process; in contrast, uptake into tumour tissue is slow to negligible. Preclinical studies have shown that pretreatment with amifostine provides protection of normal tissues from the cytotoxic effects of alkylating agents, organoplatinums, anthracyclines, taxanes and radiation. Normal tissues protected include bone marrow, kidney, neural tissues, the heart, intestinal crypt cells and pulmonary tissues. Additionally, the mutagenic and carcinogenic effects of these modalities are also attenuated. With respect to bone marrow, preclinical studies have shown significant protection of progenitor cells that give rise to the red and white cells and platelets. Comparative in vitro and in vivo studies using murine and human tumour xenografts show no decrease of antitumour effects of these same therapies despite the protection of normal organs. The unique preclinical profile of amifostine serves as a model for the clinical development programme for this important new broad-spectrum cytoprotective agent.

Amifostine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential as a radioprotector and cytotoxic chemoprotector

Amifostine (WR-2721) was originally developed as a radioprotective agent. In animals, it protects normal tissues from the damaging effects of irradiation and, as shown in more recent studies, of several cytotoxic agents. Protection of tumours is generally reduced compared with that of normal tissues in animals, suggesting that amifostine may increase the therapeutic window of cytotoxic therapies. Clinical data concerning amifostine suggest that cytotoxic chemotherapy-induced haematological toxicity and cisplatin-induced neurotoxicity, nephrotoxicity and ototoxicity are decreased upon administration of amifostine prior to cytotoxic drugs. Similarly, amifostine reduces damage to normal tissues caused by radiotherapy. Available data show that this protection is achieved without adversely affecting tumour response or patient survival. In 1 large trial, the reduction in cyclophosphamide- and cisplatin-related toxicities manifested as a decrease in the incidence and severity of neutropenia-related fever and sepsis and in the number of patients with ovarian cancer who discontinue therapy before completion of treatment, thus improving the tolerability of this antineoplastic regimen. In addition, the incidences of cisplatin-induced nephro- and neurotoxicity were reduced. Increased doses of cytotoxic therapy have also been administered when amifostine was given prior to therapy, which may increase tumour response. The predominant adverse effect associated with amifostine are hypotension, nausea and vomiting, somnolence and sneezing. Thus, amifostine is likely to be a useful adjuvant to the treatment of patients with malignancy, particularly those receiving cyclophosphamide plus cisplatin. discontinued therapy before completion of treatment, thus improving the tolerability of this antineoplastic regimen. In addition, the incidences of cisplatin-induced.

Carboplatin combined with amifostine, a bone marrow protectant, in the treatment of non-small-cell lung cancer: a randomised phase II study

Amifostine (WR-2721), a thiol compound, has been shown to protect normal tissue from alkylating agents and cisplatin-induced toxicity without loss of anti-tumour effects. To confirm this result, we conducted a phase II randomised trial to determine if the addition of amifostine reduces the toxicity of carboplatin without loss of anti-tumour activity in patients with inoperable non-small-cell lung cancer (NSCLC). After the first course of carboplatin (600 mg m-2 i.v. infusion), 21 patients were randomised to receive three cycles of carboplatin alone (C arm) or three infusions of amifostine at 910 mg m-2 (CA arm) at 28 day intervals. The amifostine was given 20 min before and at 2 and 4 h after carboplatin. Since the 910 mg m-2 amifostine infusion led to hypotension in six patients, the dosage was reduced by 25%, to 683 mg m-2 t.i.d., in the other four patients. Amifostine was well tolerated at this dose level. Five patients in the CA arm and three in the C arm had their planned treatment discontinued owing to progressive disease (n = 3), amifostine side-effects (hypotension, sneezing and sickness, n = 4), and carboplatin-induced thrombocytopenia (n = 1). Bone marrow and renal function at study entry and after the first course of carboplatin before randomisation were similar in both treatment arms. Twenty courses of carboplatin+amifostine have been compared with 25 courses of carboplatin alone. Although there was no statistically significant difference with respect to haematological values comparing both arms, the median time to platelet recovery (> 100 x 10(9) l-1) (13.5 days vs 21 days; P = 0.04) and the need for hospitalisation for i.v. antibiotic and other supportive treatment tended to be reduced in the CA arm (0/20 vs 6/25 patient courses; P = 0.06). Response rates and median survival (14 vs 9 months) were no different, excluding tumour protection activity by amifostine. These results with a small number of patients suggest that amifostine given with carboplatin may reduce the duration of thrombocytopenia and hospitalisation.

Degradation of 2-(3-aminopropylamino)-ethanethiol (WR-1065) by Cu-dependent amine oxidases and influence on glutathione status of Chinese hamster ovary cells

The radioprotective drug 2-(3-aminopropylamino)ethanethiol (WR-1065) can be degraded when incubated in cell culture medium in vitro. The degradation reaction consumes oxygen and results from the action of Cu-dependent amine oxidases present in the serum content of the medium. Analysis of the degradation products of WR-1065 demonstrates the formation of cysteamine, acrolein and H2O2. WR-2721, the inactive prodrug of WR-1065, is not a substrate for these enzymes. Extracellular degradation of WR-1065 by Cu-dependent amine oxidases leads to an intracellular depletion of glutathione (GSH) in Chinese hamster ovary (CHO) cells and to reduction of clonogenic cell survival. Addition of aminoguanidine, an inhibitor of Cu-dependent amine oxidases, protects CHO cells from the toxic effects of WR-1065 and under these conditions an increase of intracellular GSH levels occurs. These data demonstrate that WR-1065 can be degraded to toxic compounds by the presence of Cu-dependent amine oxidases which might have further implications for the clinical use of WR-2721.

Radioprotection of the rat small intestine with topical WR-2721

BACKGROUND

The classic radioprotectant WR-2721 has been shown to reduce the severity of small bowel injury when administered systemically shortly before irradiation is delivered. This study tested the possibility that WR-2721 could provide protection when applied topically to intestinal mucosa. The second question addressed was the influence of pH on the effectiveness of this agent.

METHODS

The model used involved irradiation of exteriorized rat small bowel. A length of intestine was compartmentalized. The various individual segments were filled with a lumenal Tris buffer (pH 9), WR-2721, or a combination of these two, then irradiated with 1100 cGy. The animals were sacrificed 5 days later. Surviving crypt cells and mucosal height were the criteria used to quantitate mucosal injury.

RESULTS

The pH 9 buffer alone provided a small (16%) but significant preservation of crypt cell numbers. WR-2721 improved crypt survival by 54% at neutral pH, 83% at pH 9.

CONCLUSIONS

These data indicate that WR-2721, when applied topically to the small bowel mucosa of the rat before irradiation, provides substantial protection against radiation damage. The degree of benefit is amplified greatly when the drug is in an alkaline medium.

Lumenal route for intestinal radioprotection

The intestine, being highly sensitive to radiation injury, is the limiting factor in the delivery of abdominal and pelvic radiation. Attempts at intestinal radioprotection have generally involved systemic administration of agents that are moderately toxic and that may protect the target malignancy. The lumenal route for intestinal radioprotection provides a high concentration at the mucosa without significant systemic effects. This paper reviews studies of intestinal radiation radioprotection by intralumenal agents. Our model involved irradiation of exteriorized rat small bowel containing drugs in isolated segments. Surviving crypts were quantitated as a measure of injury 5 days later, and the individual segments were compared. Modest protection was found with lumenal alkalinization and with neutralization of bile salts or pancreatic enzymes. Similar protection was identified with some nonsteroidal anti-inflammatory agents, methylprednisolone, and selected antioxidants. Marked protection was observed with lumenal Lazaroid.

In vivo protection by the aminothiol WR-2721 against neutron-induced carcinogenesis

The ability of the compound S-2-(aminopropylamino)ethylphosphorothioic acid, designated WR-2721, to protect against neutron-induced carcinogenesis was investigated. Both sexes of the B6CF1 mouse were injected i.p. with 400 mg/kg of WR-2721 30 min prior to being irradiated by 10 cGy of neutrons. Neoplastic mortality in the groups receiving thiol was either reduced or delayed relative to irradiated mice not given protector. However, the time at which the protective effect of WR-2721 was expressed depended on the sex of the animal. Thiol-related shifts in the time of neoplastic death in females occurred only in the first half of the lifespan. Once a female survived to the mean age at death, no difference in the pattern of mortality could be detected between control and WR-2721-treated mice exposed to neutrons. Irrespective of thiol treatment, the timing of tumour-related death was nearly identical during the first half of life for males exposed to neutrons. In the last half of the lifespan, survival of thiol-protected males was enhanced relative to saline-injected males and even exceeded that observed in the control population.

Clearance of S-(3-amino-2-hydroxypropyl) phosphorothioate (WR-77913) in rats

Complications of radiotherapy in the treatment of retinal and choroidal neoplastic diseases include cataract formation, radiation retinopathy, neovascular glaucoma, cystoid macular edema, and subretinal neovascularization. These side effects may be minimized by the use of compounds known to have a protective effect on normal ocular tissues without impeding the benefits of therapy. Phosphorothioates, first developed under the Antiradiation Drug Development Program of the U.S. Army Medical Research and Development Command, have been reported to protect normal tissues during radiation therapy in a variety of animal models. One of the phosphorothioates, WR-77913 (S-[3-amino-2-hydroxylpropyl]phosphorothioate) was found to inhibit cataract formation in rats after radiation exposure. To test the efficacy of WR-77913 in the retina, we established a high-pressure liquid chromatography method to measure the levels of dephosphorylated WR-77913 and studied the drug's clearance from the lens, retina, blood, kidney, and liver in rats.