Subcutaneous administration of amifostine (ethyol) is equivalent to intravenous administration in a rat mucositis model

PURPOSE: Amifostine (Ethyol) is currently approved for intravenous (IV) administration to prevent xerostomia in patients receiving radiotherapy for head-and-neck cancer. Recently, subcutaneous (SC) administration has been explored as an alternative route. To determine whether SC administration was equivalent to IV administration, we used models to follow pharmacokinetics and oral mucosal protection in rats. METHODS: Amifostine was administered to rats at doses of 200, 100, or 50 mg/kg (1300, 650, or 325 mg/m(2)) IV or SC at various times before radiation at 15.3 Gy (protection studies) or harvest of blood and tissues for analysis by HPLC (pharmacokinetic studies). RESULTS: Amifostine administered IV or SC 1 h before radiation protected rats from mucositis, but the protective effect was more prolonged when amifostine was administered SC. Tissue levels of the active metabolite (WR-1065) were equivalent after SC administration. The correlation between tissue levels of WR-1065 and protection was strong, but that between blood levels of WR-1065 and protection was only weak. CONCLUSION: These data demonstrate that, in a rat model, SC administration of amifostine was at least as effective as that by IV.     

Tissue levels of WR-1065, the active metabolite of amifostine (Ethyol), are equivalent following intravenous or subcutaneous administration in cynomolgus monkeys

Amifostine (Ethyol) is a cytoprotective drug approved for the reduction of xerostomia in head and neck cancer when administered to patients receiving postoperative radiation therapy. Although amifostine is approved for intravenous infusion, the off-label subcutaneous route of administration has become more prevalent. Although human patient data indicate higher plasma bioavailability of the active metabolite (WR-1065) following intravenous compared to subcutaneous administration, there are no corresponding data showing human tissue levels of WR-1065 following either route of administration due to the difficulty in obtaining human specimens. In our study we compared plasma and tissue pharmacokinetics of WR-1065 in primates following both routes of administration. Monkeys received amifostine at a dose of 260 mg/m2 either intravenously or subcutaneously. Plasma samples were analyzed for total WR-1065 by reverse-phase high-pressure liquid chromatography (HPLC) and fluorescence detection up to 4 h after amifostine administration. Tissues were analyzed for free WR-1065 by reverse-phase HPLC and electrochemical detection 30 and 60 min after administration. Following intravenous administration, plasma WR-1065 levels peaked rapidly and showed a bi-exponential decline, while following subcutaneous administration WR-1065 levels rose slowly and declined exponentially. The relative plasma bioavailability of WR-1065 given subcutaneously was lower at 30 and 60 min. Interestingly, after 30 min, tissues showed equal or slightly greater concentrations of WR-1065 following subcutaneous administration. Levels following 60 min were comparable following both routes. The plasma bioavailability studies performed in primates confirm human plasma data. Expanding the study to evaluate primate tissue levels of WR-1065 revealed that despite lower plasma bioavailability following subcutaneous administration, tissue levels of the active metabolite were surprisingly greater than or equal to those measured in animals that received the drug intravenously. These studies strengthen the argument for subcutaneous administration of amifostine in radiation oncology.     

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.     

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).     

Inhibition of spontaneous metastases formation by amifostine.

Amifostine was investigated for its ability to inhibit spontaneous metastases formation using the well-characterized murine sarcoma, Sa-NH. Amifostine was administered intraperitoneally at a dose of 50 mg/kg every other day for 6 days to C3Hf/Kam mice until tumors reached an average size of 8-8.5 mm in diameter. Amifostine was again administered immediately after surgical removal of the tumor-bearing limbs by amputation, and then once more 2 days later. Twenty-one days later, animals were evaluated for the presence of spontaneously developed pulmonary metastases. Nontumor-bearing control animals were sham treated using the same dosing and surgery schedules. Treatment with amifostine appeared to slightly delay tumor growth, that is, 13 vs. 12 days for tumors to reach an average diameter of 8 mm. Amifostine reduced both the incidence of pulmonary metastases formed in experimental animals from 77% to 57% (p < 0.05), and their average number per animal from 12.8 +/- 5.4 (SEM) to 2.9 +/- 1.1 (SEM). The effect of amifostine exposure on serum levels of the angiogenesis inhibitor angiostatin was also determined using Western blot analysis. Consistent with the antimetastatic effect, exposure of animals to 50 mg/kg of amifostine resulted in a 4-fold enhanced serum level of angiostatin above control levels. This phenomenon occurred in tumor-bearing and nontumor-bearing animals. The effects of amifostine on matrix metalloproteinase (MMP) enzymatic activity was also determined using gelatin zymography. Conditioned growth medium collected from Sa-NH cells grown to confluency was exposed to various concentrations of SH, i.e., 2-[(aminopropyl)amino]ethane-thiol (WR-1065), the active thiol form of amifostine, for either 30 min or 18 hr. WR-1065, as a function of increasing dose and time, inhibited the enzymatic activities of MMP-2 and MMP-9. At a concentration and time of exposure likely to be achieved in vivo, that is, 40 microM and 30 min, MMP-2 and MMP-9 activities were reduced to between 30% and 40% of control values. Consistent with these affects, WR-1065 was also found to be effective in inhibiting the ability of Sa-NH cells to migrate through Matrigel membranes. After an 18-hr exposure under in vitro conditions, WR-1065 at concentrations of 4, 40 and 400 microM, and 4 mM, inhibited Sa-NH migration to 11%, 44%, 81% and 97% of control values, respectively. The abilities of amifostine and its active thiol WR-1065 to stimulate angiostatin production in mice, and to inhibit the MMP enzymatic activities and invasion ability of Sa-NH cells under in vitro conditions, are consistent with the observed antimetastatic effects exhibited against Sa-NH tumors growing in vivo.     

Phase III randomized trial of amifostine as a radioprotector in head and neck cancer.

PURPOSE: Radiotherapy for head and neck cancer causes acute and chronic xerostomia and acute mucositis. Amifositine and its active metabolite, WR-1065, accumulate with high concentrations in the salivary glands. This randomized trial evaluated whether amifostine could ameliorate these side effects without compromising the effectiveness of radiotherapy in these patients. PATIENTS AND METHODS: Patients with previously untreated head and neck squamous cell carcinoma were eligible. Primary end points included the incidence of grade > or =2 acute xerostomia, grade > or =3 acute mucositis, and grade > or =2 late xerostomia and were based on the worst toxicity reported. Amifostine was administered (200 mg/m(2) intravenous) daily 15 to 30 minutes before irradiation. Radiotherapy was given once daily (1.8 to 2.0 Gy) to doses of 50 to 70 Gy. Whole saliva production was quantitated preradiotherapy and regularly during follow-up. Patients evaluated their symptoms through a questionnaire during and after treatment. Local-regional control was the primary antitumor efficacy end point. RESULTS: Nausea, vomiting, hypotension, and allergic reactions were the most common side effects. Fifty-three percent of the patients receiving amifostine had at least one episode of nausea and/or vomiting, but it only occurred with 233 (5%) of 4,314 doses. Amifostine reduced grade > or =2 acute xerostomia from 78% to 51% (P<.0001) and chronic xerostomia grade > or = 2 from 57% to 34% (P=.002). Median saliva production was greater with amifostine (0.26 g v 0.10 g, P=.04). Amifostine did not reduce mucositis. With and without amifostine, 2-year local-regional control, disease-free survival, and overall survival were 58% versus 63%, 53% versus 57%, and 71% versus 66%, respectively. CONCLUSION: Amifostine reduced acute and chronic xerostomia. Antitumor treatment efficacy was preserved.     

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.     

Phase I trial and pharmacokinetics of escalating doses of paclitaxel and concurrent hyperfractionated radiotherapy with or without amifostine in patients with advanced head and neck carcinoma

BACKGROUND: Amifostine was developed to protect normal tissues from radiation exposure. The current study was undertaken to determine whether amifostine would allow the delivery of greater numbers of weekly paclitaxel treatments with concomitant, hyperfractionated radiotherapy in patients with advanced head and neck carcinoma. METHODS: Patients received radiation therapy twice daily using 1.6-gray (Gy) fractions up to a total of 70.4 Gy over an elapsed time of 6.5 weeks. All patients received paclitaxel 60 mg/m(2) once weekly starting on Day 1. The number of doses of paclitaxel was escalated from three to a maximum of six in groups of three patients. For the patients who received amifostine, a dose of 400 mg/m(2) was given intravenously over 15 minutes on Days 1-5, 8, 29-33, and 36. Patients underwent surgery for persistent tumor after radiotherapy. The plasma pharmacokinetics of paclitaxel were characterized during treatment with the first weekly dose to determine the effect of concurrently administered amifostine. RESULTS: Thirty-six patients were evaluable for this study. In the absence of amifostine, a maximum of four doses of paclitaxel were tolerated in combination with the radiotherapy. With amifostine, up to five doses of paclitaxel could be given. Generally, the treatment resulted in Grade 2 and 3 stomatitis. Overall, 69% of patients had a complete remission, and 29% had a partial remission. Both progression-free survival and overall survival were 66% at 30 months. Amifostine had no effect on the pharmacokinetics of paclitaxel. CONCLUSIONS: The administration of amifostine allowed the authors to give an additional dose of paclitaxel to patients who were undergoing hyperfractionated radiotherapy for head and neck carcinoma. This treatment regimen resulted in a high frequency of complete remissions and an excellent progression-free survival pattern without compromising the plasma kinetics of paclitaxel.     

Protection of mouse bone marrow by WR-2721 after fractionated irradiation

The ability of WR-2721 to protect mouse bone marrow after single or fractionated doses of radiation was assessed using both a clonogenic assay (survival of colony-forming units spleen (CFU) and a functional assay (lethality at 30 days) of stem cell survival. Cell survival curves and dose-response curves for radiation alone and drug with radiation were constructed over the dose range of .5 to 8 Gy and 1.5 to 15 Gy, respectively. The fractionated regimen consisted of four fractions ranging from 0.5 to 1.75 Gy given at 6-hr intervals for a total treatment time of 19.5 hr. WR-2721 was given 30 min before each fraction at a dose of 200 mg/kg. The protection factor was smaller after fractionated doses than after single doses for both assays, 1.3 (95% c.l., 1.0-1.6) vs. 2.3 (95% c.l., 2.0-2.6) for CFU survival and 1.34 vs. 1.8 for lethality at 30 days. No drug cytotoxicity could be demonstrated in the fractionated schedule. These data suggest that protection by WR-2721 is dependent on size of dose and will be less after clinically relevant, small dose fractions. However, some protection does remain even in the low dose range, where proportionally more damage is due to single-hit irreparable events.     

Prevention of radiation-induced central nervous system toxicity: a role for amifostine?

PURPOSE: To review the role of amifostine (WR-2721) in ameliorating radiation-induced central nervous system (CNS) toxicity. MATERIALS AND METHODS: Literature review and presentation of preliminary animal experiments designed to test the efficacy of both intrathecal and subcutaneous application of amifostine. RESULTS: Despite its inability to cross the blood-brain barrier, amifostine appears promising because it protects blood vessels against radiation-induced damage. Vascular damage is one of the most important components in the development of CNS toxicity after radiotherapy. Furthermore, the increased permeability of the blood-brain barrier during fractionated radiotherapy might allow penetration of amifostine. Three animal studies with systemic administration found positive results after brain irradiation with different fractionation schedules, total doses and amifostine doses. One study where amifostine was given after radiotherapy showed no protection, suggesting that the timing of the drug application is crucial. Further data suggest that either intrathecal or systemic administration might protect the spinal cord as well. In our experience with spinal cord irradiation, systemic administration was more effective than intrathecal. Regarding CNS protection, the optimum dose of amifostine has yet to be determined. CONCLUSION: Several independent experiments provided preliminary evidence that modulation of the radiation response of the CNS in vivo by systemic administration of amifostine is possible and feasible. Additional studies are warranted to investigate the protective effect with differing regimens of administration, more clinically relevant fractionation regimens and longer follow-up.     

Phase I clinical and pharmacologic study of weekly cisplatin and irinotecan combined with amifostine for refractory solid tumors.

PURPOSE: This Phase I study was designed primarily to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of irinotecan and cisplatin with and without amifostine in children with refractory solid tumors. PATIENTS AND METHODS: Cisplatin, at a fixed dose of 30 mg/m(2), and escalating doses of irinotecan (starting dose, 40 mg/m(2)) were administered weekly for four consecutive weeks, every 6 weeks. After the MTD of irinotecan plus cisplatin was determined, additional cohorts of patients were enrolled with amifostine (825 mg/m(2)) support. Leukocyte DNA-platinum adducts and pharmacokinetics of cisplatin and WR-1065 (amifostine-active metabolite) were also determined. RESULTS: Twenty-four patients received 43 courses of therapy. The MTD for irinotecan administered in combination with cisplatin (30 mg/m(2)) was 50 mg/m(2). The DLTs of this combination were neutropenia and thrombocytopenia. With the addition of amifostine, at an irinotecan dose of 65 mg/m(2) and cisplatin dose of 30 mg/m(2), the DLT was hypocalcemia. Although no objective responses were observed, six patients received at least three courses of therapy. The amounts of platinum adducts (mean +/- SD) were 10 +/- 20 molecules/10(6) nucleotides. The maximum plasma concentrations (C(max)) for free cisplatin and WR-1065 were 4.5 +/- 1.6 micro M and approximately 89 +/- 10 micro M, respectively. The half-life (t(1/2)) for free plasma cisplatin was 25.4 +/- 5.4 min. The initial t(1/2) for plasma WR-1065 was approximately 7 min and terminal t(1/2) approximately 24 min. CONCLUSION: The combination of cisplatin and irinotecan administered weekly for 4 weeks in children with refractory cancer is well tolerated. Amifostine offers some myeloprotection, likely permitting >/=30% dose escalation for irinotecan, when administered in a combination regimen with cisplatin. However, effective antiemetics and calcium supplementation are necessary with the use of amifostine. Further escalation of irinotecan dosing, using these precautions for amifostine administration, may be possible.     

In Vitro Protection from Cisplatin-induced Neurotoxicity by Amifostine and its Metabolite WR1065

Cisplatin-induced neuropathy is a major dose-limiting toxicity. Counteraction by amifostine and its metabolite WR1065 may reduce peripheral neurotoxicity in a number of patients. Using the nerve growth factor (NGF)-dependent neurite outgrowth from the PC12 pheochromocytoma cell line as an in vitro assay for neurotoxicity, the protective effects of amifostine and WR1065 against cisplatin action on neurite formation by PC12 cells were studied.Cisplatin in a concentration of 10 µg/ml significantly decreased the percentage of neurite forming cells from 84% to 40%. Amifostine in doses of 0.4 and 0.8 mM proved to protect significantly against the cisplatin-induced decrease in neurite formation, when co-incubated with cisplatin. Also the metabolite WR1065 protected significantly against cisplatin neurotoxicity in a dose of 0.12 mM. Our results show a significant protection by amifostine and its main metabolite WR1065 against cisplatin-induced neurotoxicity using an in vitro model.     

Chemical radioprotection: a critical review of amifostine as a cytoprotector in radiotherapy

The use of chemical radioprotectors represents an obvious strategy to improve the therapeutic index in radiotherapy. Amofostine (WR-2721) has recently been approved for use in head and neck cancer to protect against radiation-induced xerostomia. Currently, the question has arisen whether amifostine could be used for radioprotection in broader terms. Amifostine may have the potential to enable intensified treatment by ameliorating mucosal reactions that are often a limiting factor in accelerated fractionation or concomitant chemoradiation. However, it has as yet not been clarified whether sufficient amifostine to reduce mucositis can be administered before each radiation fraction without causing unacceptable toxicity. Also, the optimal dosage and schedule of amifostine in chemoradiation combinations have not yet been established. The major concern related to radioprotectiors is the potential hazard of collateral tumor protection. A number of clinical studies have concluded that amifostine does not reduce antitumor efficacy. However, not even the largest study conducted, with over 300 patients, has sufficient statistical power to detect a clinically significant reduction in tumor control rate. To put this issue ultimately to a rest, a clinical trial with a sufficient accrual to definitely rule out a tumor protective effect of amifostine needs to be conducted. Substances reducing radiation-induced toxicity by modulating the biological response to radiation injury may represent an alternative concept in radioprotection. However, such agents are still at a developmental stage.     

Commentary: the pharmacological antioxidant amifostine -- implications of recent research for integrative cancer care

Amifostine is a pharmacological antioxidant used as a cytoprotectant in cancer chemotherapy and radiotherapy. It is thought to protect normal tissues relative to tumor tissue against oxidative damage inflicted by cancer therapies by becoming concentrated at higher levels in normal tissues. The degree to which amifostine nevertheless accumulates in tumors and protects them against cancer therapies has been debated. Guidelines have been published that direct its use in chemotherapy and radiation, taking into consideration the concerns of tumor protection. In this article, clinical studies of amifostine appearing since the publication of the most recent set of guidelines are reviewed. Randomized and nonrandomized trials of regimens involving chemo-therapeutic agents (chemotherapy, chemoradiation, conditioning regimens for bone marrow transplant) are discussed. Nineteen studies showed positive effects for amifostine reducing the level of side effects of these regimens, while 9 showed no effect and 1 had a questionable result. Clinically relevant levels of amifostine toxicity were observed in several studies, but subcutaneous administration may reduce such toxicity. Amifostine showed protection against mucositis, esophagitis, neuropathy, and other side effects, although protection against cisplatin-induced ototoxicity was not observed. No evidence of tumor protection was observed. Amifostine may enable populations unable to tolerate conventional cancer therapy to receive treatment of their cancers, even if some degree of tumor protection is eventually discovered. The authors discuss the implications of this research for patient populations seen in integrative cancer care centers and for research on phytochemical antioxidants such as vitamins and carotenoids.     

Selective exclusion by the polyamine transporter as a mechanism for differential radioprotection of amifostine derivatives.

Amifostine metabolites WR-1065 and the disulfide WR-33278 are thiol-containing polyamine analogues with potent radio- and chemoprotective properties. Some studies suggest that amifostine exerts differential cytoprotection in normal versus neoplastic tissues, but this finding remains controversial. To assess the role of the polyamine transport system in radioprotection by amifostine derivatives, human DU-145 prostate cancer cells were transfected with a cDNA that encodes antizyme (OAZ), a polyamine-inducible protein that suppresses polyamine transport under control of a minimal heat shock promoter. Selected clones expressing OAZ displayed heat shock-dependent suppression of polyamine uptake. When added to culture medium under nonreducing conditions, both WR-1065 and WR-33278 were detected as the disulfide form. Each derivative protected both parental and OAZ-transfected DU-145 cells from X-ray-induced cell killing at 37 degrees C. When cultures were heat shocked at 42 degrees C, both derivatives protected parental, but not OAZ-transfected cells from radiation-induced cell killing. Treatment of DU-145 cells with difluoromethylornithine (DFMO) suppressed intracellular putrescine and spermidine content, but increased the uptake of WR-33278-derived aminothiols. The concentration-dependent radioprotection of DU-145 cells by WR-33278 was enhanced by DFMO. Addition of exogenous putrescine reduced WR-33278-mediated radioprotection in both DFMO-treated and untreated DU-145 cells. These data demonstrate that negative regulation of the polyamine transporter, mediated by polyamines or antizyme, suppresses the uptake and radioprotective activity of amifostine derivatives. Selective exclusion of amifostine derivatives by the polyamine transporter could account for differential radio- or chemoprotection in normal versus neoplastic tissues in specific situations.     

Amifostine Does Not Inhibit the Toxic Effects of Anthracycline Derivates or Mitoxantrone on MDR Tumor Cell Lines

In this work three hum 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.     

Serious adverse effects of amifostine during radiotherapy in head and neck cancer patients

Background and purpose: Amifostine has been shown to protect against xerostomia induced by radiotherapy for head and neck cancer, but its impact on the therapeutic index is unknown. This is the first report focusing on amifostine related adverse effects leading to discontinuation of amifostine treatment.

Patients and methods: Thirty-nine patients from two centers irradiated for head and neck cancer received i.v.-infusions of amifostine prior to each radiation fraction. In a phase III study, two daily amifostine doses, 200 mg/m² (n=21) and 340 mg/m² (n=18), were compared for protection against radiation induced toxicity. Total radiation dose was 60–70 Gy (2 Gy per fraction), nine patients received concurrent chemotherapy with cisplatin/5-FU. amifostine was usually discontinued after >1 episode of serious toxicity during subsequent treatment sessions.

Results: In 16/39 patients (41%) amifostine was discontinued due to severe adverse effects, which led to discontinuation of the phase III study. In four of 16 patients radiotherapy was delayed due to amifostine related adverse effects for 1–3 days. Discontinuation occurred more often in patients receiving chemotherapy. The results led to a literature review for amifostine treatment during radiotherapy in head and neck cancer patients. Regarding our series and published series using an amifostine schedule comparable to ours, total discontinuation rate was 27% (57/214). Discontinuation was significantly influenced by chemotherapy (P=0.007), but not by amifostine dose (P=0.156).

Conclusion: Daily i.v. administration of amifostine during radiotherapy in head and neck cancer is associated with a high rate of serious adverse effects leading to discontinuation of amifostine treatment and sometimes delay of radiotherapy.     

Selective cytoprotection with amifostine in concurrent radiochemotherapy for head and neck cancer

Background: Amifostine has reduced toxicities associated with radiationtherapy and platinum-based chemotherapy. In a phase II randomized trial, weinvestigated the ability of amifostine to reduce the toxicity of carboplatinplus radiotherapy (RCT) in patients with head and neck cancer.Patients and methods: Thirty-nine patients with stage III or IV squamouscell carcinomas of the head and neck received RCT (following surgery or asprimary treatment). Radiotherapy was given five days per week with dailyfractions of 2 Gy, up to a total dose of 60 Gy in conjunction withcarboplatin 70 mg/m² on days 1 through 5 and days 21 through26. Eligible patients were randomised to receive RCT alone or preceded by arapid infusion of amifostine (500 mg) on the days when carboplatin wasadministered.Results: Patients receiving amifostine + RCT (n = 25) had significantlyreduced mucositis (P = 0.0001) and xerostomia (P = 0.0001) in comparisonwith patients receiving RCT alone (n = 14). Additionally, patients receivingamifostine + RCT had significantly less thrombocytopenia (P = 0.001) andleukopenia (P = 0.001). At 12 months following therapy, 79% ofpatients receiving amifostine + RCT had no evidence of disease compared with64% of those receiving RCT alone.Conclusions: Amifostine reduces the RCT-induced toxicities in patients withhead and neck cancer and has no negative impact on antitumour efficacy.     

WR-1065, the active form of amifostine, protects HL-60 cells but not peripheral blood mononuclear cells from radiation and etoposide-induced apoptosis

PURPOSE: Developing myeloid cells are particularly sensitive to chemotherapy and ionizing radiation. Mature cells of the hematopoietic lineages, such as are found in the peripheral blood mononuclear cells (PBMCs), are much less sensitive for reasons that are not yet understood. Protecting the myeloid precursors from radiation or chemotherapy is an important goal. METHODS: We have used fluorescence microscopy to assess the ability of WR-1065, the active metabolite of amifostine (Ethyol), to protect cultured myeloid leukemic HL-60 cells or freshly isolated PBMCs from the induction of apoptosis by ionizing radiation or etoposide. RESULTS: WR-1065 greatly reduced the percentage of radiation-induced apoptosis in the p53 negative HL-60 cells 24 h after exposure to 8 Gy. WR-1065 also greatly reduced the percentage of HL-60 cells undergoing apoptosis 24 h after a 1-h exposure to 1 microM etoposide. The pan-caspase inhibitor ZVAD-fmk completely inhibited radiation-induced apoptosis in HL-60 cells when present for the first hour after exposure to radiation, but had no effect on cell survival. In contrast, neither WR-1065 nor ZVAD-fmk reduced the level of radiation-induced apoptosis in normal human PBMCs. CONCLUSION: These results suggest that pro-apoptotic pathways are present in immature myeloid cells that can be selectively protected from radiation or chemotherapy-induced apoptosis.