Radioprotection by WR-2721 of gamma-irradiated rat parotid gland: effect on gland weight and secretion at 8-10 days post irradiation

Protective Effect of Alpha-Lipoic Acid on Salivary Dysfunction in a Mouse Model of Radioiodine Therapy-Induced Sialoadenitis

Radioiodine (RI) therapy is known to cause salivary gland (SG) dysfunction. The effects of antioxidants on RI-induced SG damage have not been well described. This study was performed to investigate the radioprotective effects of alpha lipoic acid (ALA) administered prior to RI therapy in a mouse model of RI-induced sialadenitis. Four-week-old female C57BL/6 mice were divided into four groups (n = 10 per group): group I, normal control; group II, ALA alone (100 mg/kg); group III, RI alone (0.01 mCi/g body weight, orally); and group IV, ALA + RI (ALA at 100 mg/kg, 24 h and 30 min before RI exposure at 0.01 mCi/g body weight). The animals in these groups were divided into two subgroups and euthanized at 30 or 90 days post-RI treatment. Changes in salivary ^99mTc pertechnetate uptake and excretion were tracked by single-photon emission computed tomography. Salivary histological examinations and TUNEL assays were performed. The ^99mTc pertechnetate excretion level recovered in the ALA treatment group. Salivary epithelial (aquaporin 5) cells of the ALA + RI group were protected from RI damage. The ALA + RI group exhibited more mucin-containing parenchyma and less fibrotic tissues than the RI only group. Fewer apoptotic cells were observed in the ALA + RI group compared to the RI only group. Pretreatment with ALA before RI therapy is potentially beneficial in protecting against RI-induced salivary dysfunction.

Iatrogenic Causes of Salivary Gland Dysfunction

Saliva is important for maintaining oral health and function. There are instances when medical therapy is intended to decrease salivary flow, such as during general anesthesia, but most instances of iatrogenic salivary gland dysfunction represent untoward or unavoidable side-effects. The clinical expression of the salivary dysfunction can range from very minor transient alteration in saliva flow to a total loss of salivary function.

The most common forms of therapy that interfere with salivation are drug therapies, cancer therapies (radiation or chemotherapy), and surgical therapy. These therapies can affect salivation by a number of different mechanisms that include: Disruption of autonomic nerve function related to salivation, interference with acinar or ductal cell functions related to salivation, cytotoxicity, indirect effects (vasoconstrictiondilation, fluid and electrolyte balance, etc.), and physical trauma to salivary glands and nerves.

A wide variety of drugs is capable of increasing or decreasing salivary flow by mimicking autonomic nervous system actions or by directly acting on cellular processes necessary for salivation; drugs can also indirectly affect salivation by altering fluid and electrolyte balance or by affecting blood flow to the glands. Ionizing radiation can cause permanent damage to salivary glands, damage that is manifest as acinar cell destruction with subsequent atrophy and fibrosis of the glands. Cancer chemotherapy can cause changes in salivation, but the changes are usually much less severe and only transient. Finally, surgical and traumatic injuries interfere with salivation because of either disruption of gland innervation or gross physical damage (or removal) of glandular tissue (including ducts).

New and safe experimental model of radiation-induced neurovascular histological changes for microsurgical research

The aim is to create a new and safe experimental model of radiation-induced neurovascular histological changes with reduced morbidity and mortality for use with experimental microsurgical techniques. Seventy-two Sprague-Dawley rats (250-300 g) were divided as follows: Group I: control group, 24 rats clinically evaluated during six weeks; Group II: evaluation of acute side-effects (two-week follow-up period), 24 irradiated (20 Gy) rats; and Group III: evaluation of subacute side-effects (six-week follow-up period), 24 irradiated (20 Gy) rats. Variables included clinical assessments, weight, vascular permeability (arterial and venous), mortality and histological studies. No significant differences were observed between groups with respect to the variables studied. Significant differences were observed between groups I vs II-III regarding survival rates and histological changes to arteries, veins and nerves. Rat body weights showed progressive increases in all groups, and the mortality rate of the present model is 10.4% compared with 30-40% in the previous models. In conclusion, the designed model induces selective changes by radiotherapy in the neurovascular bundle without histological changes affecting the surrounding tissues. This model allows therapeutic experimental studies to be conducted, including the viability of microvascular and microneural sutures post radiotherapy in the cervical neurovascular bundle.

Amifostine for salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer

BACKGROUND

Radioactive iodine treatment for differentiated thyroid cancer possibly results in xerostomia. Amifostine has been used to prevent the effects of irradiation to salivary glands. To date, the effects of amifostine on salivary glands in radioactive iodine treated differentiated thyroid cancer remain uncertain.

OBJECTIVES

To assess the effects of amifostine on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer.

SEARCH STRATEGY

Studies were obtained from computerized searches of MEDLINE, EMBASE, The Cochrane Library and paper collections of conferences held in Chinese.

SELECTION CRITERIA

Randomised controlled clinical trials and quasi-randomised controlled clinical trials comparing the effects of amifostine on salivary glands after radioactive iodine treatment for differentiated thyroid cancer with placebo and a duration of follow up of at least three months.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data.

MAIN RESULTS

Two trials with 130 patients (67 and 63 patients randomised to intervention versus control) were included. Both studies had a low risk of bias. Amifostine versus placebo showed no statistically significant differences in the incidence of xerostomia (130 patients, two studies), the decrease of scintigraphically measured uptake of technetium-99m by salivary or submandibular glands at twelve months (80 patients, one study), and the reduction of blood pressure (130 patients, two studies). Two patients in one study collapsed after initiation of amifostine therapy and had to be treated by withdrawing the infusion and volume substitution. Both patients recovered without sequelae. Meta-analysis was not performed on the function of salivary glands measured by technetium-99m scintigraphy at three months after high dose radioactive iodine treatment due to the highly inconsistent findings across studies (I(2) statistic 99%). None of the included trials investigated death from any cause, morbidity, health-related quality of life or costs.

AUTHORS' CONCLUSIONS

Results from two randomised controlled clinical trials suggest that the amifostine has no significant radioprotective effects on salivary glands in high-dose radioactive iodine treated differentiated thyroid cancer patients. Moreover, no health-related quality of life and other patient-oriented outcomes were evaluated in the two included trials. Randomised controlled clinical trials with low risk of bias investigating patient-oriented outcomes are needed to guide treatment choice.

Radioprotective effect of amifostine on parotid gland functioning is region dependent

PURPOSE

To investigation the protective ability of amifostine during partial irradiation of the rat parotid gland.

METHODS AND MATERIALS

Single-dose X-ray irradiation was performed by use of collimators with conformal radiation portals for either the 100% volume (15 Gy) or the 50% cranial/caudal partial parotid gland volumes (30 Gy). Amifostine was administered intraperitoneally at a dose of 250 mg per kg body weight, 25 minutes before irradiation. Saliva flow rates, gland weights, and the tissues of the individual lobes were investigated up to 1 year after treatment.

RESULTS

A clear protective effect of amifostine was found against loss of saliva flow, the altered appearance of gross morphology, loss of gland weight, and histopathologic changes for the 100% volume gland irradiations and for the 50% volume cranial irradiations but not for the 50% volume caudal irradiations.

CONCLUSIONS

The protective ability of amifostine is strongly dependent on the irradiated glandular region and observed for later damage only. The major effect of the drug seems to be the prevention of volume effects caused by secondary damage that occurs in shielded parts of the gland. The results of the present study show that understanding of the anatomy and physiology of organs that are to be spared is necessary to ensure optimal preservation of function.

A Comparative Study on the Protection Profile of Lidocaine, Amifostine, and Pilocarpin on the Parotid Gland during Radiotherapy

The aim of this study was to evaluate the individual and the synergetic radioprotective effect of lidocaine, amifostine, and pilocarpin on the parotid gland. Forty-nine rabbits were randomized into seven groups (n = 7)--control, irradiated sham-treated, irradiated/lidocaine-pretreated, irradiated/amifostine-pretreated, irradiated/pilocarpin-pretreated, irradiated/lidocaine + pilocarpin-pretreated, and irradiated/amifostine + pilocarpin-pretreated groups. One week before irradiation (15 Gy) and 72 hours as well as 1 month afterward, the parotid gland was investigated morphologically, sialoscintigraphically, and immunohistochemically with the use of tenascin-C and alpha smooth muscle actin. Compared with control animals, there was a significant reduction of the salivary ejection fraction in the irradiated untreated group 72 hours following radiation. Only animals pretreated with lidocaine or amifostine (alone or combined with pilocarpin) showed a slight nonsignificant reduction of salivary ejection fraction. Immunohistochemically, we observed a significant loss of alpha smooth muscle actin and an up-regulation of tenascin-C expression in irradiated/untreated glands. These changes were less evident in animals pretreated with lidocaine or lidocaine + pilocarpin. Amifostine and pilocarpin did not show any influence on tenascin-C or alpha smooth muscle actin expression. Ultrastructural damage was observed in irradiated untreated and pilocarpin-pretreated glands. In contrast, lidocaine and amifostine could largely preserve the glandular ultrastructure. One month postradiation, all changes were regressive regardless of treatment protocol. Potential radioprotective agents show different effects on both morphology and function of the parotid gland. Associated immunohistochemical and ultrastructural findings could prove the prevailed protection profile of lidocaine. This may provide a prophylactic approach in the field of radioprotection of salivary glands.

In vivo Study to Evaluate the Protective Effects of Amifostine on Radiation-Induced Damage of Testis Tissue

OBJECTIVE

To investigate the early protective effects of amifostine against radiation-induced damage on rat testis tissue.

METHODS

Eighty adult male Wistar rats were randomized to 4 groups: Saline solution was given to group A for control, 200 mg/kg amifostine (WR-2721) to group B, a single fraction of 6 Gy local irradiation to testes in group C and 200 mg/kg amifostine 15-30 min before 6 Gy testicular irradiation to group D. Animals were sacrificed 3 weeks after treatment and their testes were removed for macroscopic, microscopic and ultrastructural histopathological examination.

RESULTS

The weights, widths and lengths of testes in the last 3 groups had decreased significantly when compared with the control group, but the decrease in widths after irradiation was found to be significantly less only in the amifostine plus radiation group. There was a significant reduction of testis weights in relation to the individual body weights in the irradiated testes compared with the other groups (p < 0.005), while there was no significant change of testis weight/total body weight ratio in amifostine plus irradiation group. Spermatogonium A and primary spermatocyte counts were also less in the treatment groups, and primary spermatocyte numbers were significantly higher in amifostine plus radiation group when compared with radiation alone group (p < 0.005). Pretreatment with amifostine reduced the decrease of primary spermatocyte counts by a factor of 1.28. Electron microscopic analysis did not show any cytotoxic effect of amifostine alone, and furthermore, ultrastructural findings were normal with the addition of amifostine prior to irradiation, though there was damage in the radiation exposure group.

CONCLUSION

Amifostine when given alone by itself appears to cause adverse alterations in testis tissue; however, it has a radioprotective effect on spermiogenetic cells when used prior to radiation.

The stable nitroxide tempol facilitates salivary gland protection during head and neck irradiation in a mouse model

PURPOSE

Radiotherapy is commonly used to treat a majority of patients with head and neck cancers. The long-term radiation-induced reduction of saliva output significantly contributes to the posttreatment morbidity experienced by these patients. The purpose of this study was to test the ability of the stable-free radical Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), an established radioprotector, to prevent radiation-induced salivary hypofunction in mice.

EXPERIMENTAL DESIGN

The heads of C3H mice were exposed to a range of single radiation doses with or without an i.p. injection of 275 mg/kg Tempol 10 min before treatment. Salivary gland output was assessed 8 weeks postirradiation.

RESULTS

Radiation caused a dose-dependent reduction in salivary flow in this model. Tempol treatment alone significantly reduced radiation-induced salivary hypofunction. The combination of Tempol with mouth/nose shielding showed essentially complete radiation protection at 15 Gy and approximately 75% protection at 17.5 Gy.

CONCLUSIONS

This study demonstrates for the first time that significant radioprotection of the salivary glands is possible with Tempol in C3H mice.

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.

[Mouth dryness and burning sensation of the oral mucosa: causes and possibilities for treatment]

Both sets of complaints, mouth dryness and a burning sensation of the oral mucosa, can have a variety of causes. Local and regional as well as systemic causes can be responsible for burning mouth syndrome. Diseases of the oral mucosa can have genetic, inflammatory, or neoplastic origins. Autoimmune diseases and allergies as well as different afflictions relating to internal medicine can be accompanied by a burning sensation in the oral mucosa. Neurological and psychiatric illnesses must be clarified during interdisciplinary diagnostics in order to identify idiopathic forms. The causes of mouth dryness are similarly complex. In addition to inadequate fluid intake, particularly in elderly patients, drug side effects or systemic diseases are frequently also responsible. Treatment is directed at the underlying disease; in ambiguous cases, symptomatic therapy can provide relief for medical complaints.

Preclinical modeling of improved amifostine (Ethyol) use in radiation therapy

Amifostine (Ethyol) has been evaluated clinically as a radioprotective agent for the prevention of xerostomia and mucositis for patients receiving radiotherapy (RT). Currently, amifostine is approved for the prevention of xerostomia in head and neck cancer patients receiving RT when administered intravenously (IV) before RT. For the clinician, there would be several advantages to administering the drug subcutaneously and to being able to show its protective effects on mucositis. The authors have developed a rat RT model to examine the protective effects of amifostine after IV and subcutaneous (SC) administration in a mucositis model. Rats (5 per group) were given 200 mg/kg (human dose equivalent of approximately 1,300 mg/m(2)) of amifostine either IV or SC, and their head and neck regions were exposed to 15.3 Gy of gamma radiation 0.5, 2, 4, and 8 hours after amifostine administration. For 10 days after treatment, the oral cavities of the rats were examined for signs of mucositis. Mucosal erythema and mucosal edema were scored according to 0 through 5 and 0 through 2 scales, respectively, with the scores added to indicate overall mucositis. The average mucositis score for the untreated animals was 3.5. Rats were protected from mucositis up to 4 hours when given amifostine either IV or SC. Rats that received amifostine SC, but not IV, were protected from mucositis 8 hours after administration. Preliminary pharmacokinetic data have revealed slightly higher active metabolite (WR-1065) levels in the parotid gland and small intestine in the rats given amifostine SC compared with IV and equivalent levels in the plasma and kidney. The data showed that SC administration of amifostine gave radioprotection comparable to IV administration up to 4 hours before RT and may be more effective than IV administration at longer pretreatment intervals.

Extended-term effects of head and neck irradiation in a rodent

Radiotherapy to the head and neck is a common treatment for malignancies of the region. Unfortunately, exposure to irradiation often results in a variety of complications, most of which are localised and expressed in the short term following irradiation. However, prolonged and systemic effects may have greater clinical importance as the survival rate of head and neck irradiated patients is increasing yearly. Six groups of 18-20 rats were evaluated during a 1 year study. The non-irradiated control group was compared with 2.5 Gy, 5, 7.5, 10 and 15 Gy irradiated groups. We found a dose-dependent reduction in both survival and body weight in our rat models following a delayed, prolonged and chronic process. Dying animals were emaciated, dehydrated and starved, and many were blind and immunocompromised. While the exact underlying mechanism of this delayed, but devastating, phenomenon has not yet been determined, the delayed xerostomia inflicted on these animals may, at least partially, explain it. The clinical implications for head and neck patients require further evaluation, but our data should be considered, in the context of the available evidence for the long-term effects of head and neck irradiation in humans.

Amifostine: mechanisms of action underlying cytoprotection and chemoprevention

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

Radioprotection of salivary glands by S-2-(3-aminopropylamino)-ethylphosphorothioic (amifostine) obtained in a rabbit animal model

BACKGROUND

Impairment of salivary gland function following high-dose radioiodine treatment (HDRIT) is a well-recognized side effect of the treatment. Because differentiated thyroid cancer has an excellent prognosis, reduction of long-term side-effects is mandatory. Therefore, the aim of this study was to investigate the radioprotective effect of amifostine in a rabbit animal model.

METHODS

Salivary gland scintigraphy was performed in a total of 16 New Zealand White rabbits. Uptake of 99-Tc-pertechnetate was calculated in percentage of injected activity as a quantitative measure of both salivary gland and thyroid function. Reproducibility of salivary gland scintigraphy was evaluated in one rabbit without any intervention. Fifteen rabbits were studied prior to and up to 6 months after high-dose radioiodine treatment applying 2 GBq 131I. Ten animals received 200 mg/kg amifostine prior to high-dose radioiodine therapy, and 5 served as controls. Salivary glands were examined histopathologically.

RESULTS

Variation coefficient of parenchymal function was less than 3.8% in salivary glands. Prior to HDRIT, thyroid uptake was 0.417+/-0.373% and 0.421+/-0.241% in control and amifostine-treated rabbits, respectively. Four weeks after HDRIT, complete ablation of the thyroid was achieved in both groups. Prior to HDRIT, uptake of 99mTc-pertechnetate in salivary glands of five control rabbits was not significantly different from ten amifostine-treated rabbits. In control rabbits 6 months after HDRIT, parenchymal function was reduced significantly (p < 0.0001) by 75.3+/-5.3% and 53.6+/-17.4% in parotid and submandibular glands, respectively. In contrast, in amifostine-treated rabbits, parenchymal function was reduced by 10.6+/-3.4% and 6.5+/-4.3% (p > 0.05) in parotid and submandibular glands, respectively. Histopathologically, marked lipomatosis was observed in control animals but was negligible in amifostine-treated animals.

CONCLUSION

Parenchymal damage in salivary glands induced by high-dose radioiodine treatment can be significantly reduced by amifostine in this rabbit animal model. This corresponds to data obtained in patients with differentiated thyroid cancer.

Salivary gland protection by amifostine in high-dose radioiodine therapy of differentiated thyroid cancer

BACKGROUND

Salivary gland impairment following high-dose radioiodine treatment is a well-recognized side effect, in general caused by free radicals. Therefore, it seemed promising to evaluate the radioprotective effect of the radical scavenger amifostine in patients receiving high-dose radioiodine therapy.

PATIENTS AND METHOD

Quantitative salivary gland scintigraphy using 100 to 120 MBq Tc-99m-pertechnetate was performed in 17 patients with differentiated thyroid cancer prior to and 3 months after radioiodine treatment with 6 GBq I-131. Eight patients were treated with 500 mg/m2 amifostine prior to high-dose radioiodine treatment and compared retrospectively with 9 control patients. Xerostomia was graded according to WHO criteria.

RESULTS

In 9 control patients high-dose radioiodine treatment significantly (p < 0.01) reduced Tc-99m-pertechnetate uptake by 35.4 +/- 22.0% and 31.7 +/- 21.1% in parotid and submandibular glands, respectively. Of these 9 patients, 3 exhibited xerostomia Grade I (WHO). In contrast, in 8 amifostine-treated patients, there was no significant (p = 0.878) decrease in parenchymal function following high-dose radioiodine treatment, and xerostomia did not occur in any of them.

CONCLUSION

Parenchymal damage in salivary glands induced by high-dose radioiodine treatment can be reduced significantly by amifostine. This may help to increase patients' quality of life in differentiated thyroid cancer.

Protection against irradiation-induced damage to salivary glands by adrenergic agonist administration

PURPOSE

Irradiation [IR]-induced damage to major salivary glands is an entity first described at the beginning of our century, yet its underlying mechanism is still enigmatic. Exposure of the salivary glands to IR is often inevitable when delivering radiotherapy for malignancies of the head and neck region. Frequently, this results in rapidly developing, life-long severe xerostomia for which no adequate prevention or treatment is available. The purpose of this study was to examine the role of secretion granules in serous cells of the parotid (P) and submandibular (SM) glands as mediators in the IR-induced salivary damage. Functional parameters (flow rate and gland weight), and total body weight were examined at both early term (4 days) and extended term (2 months) post-IR in male Wistar rats exposed to 15 Gy of head and neck irradiation following stimulation for granule secretion (degranulation).

METHODS AND MATERIALS

At 4 days, it was demonstrated that IR reduced P flow rate, P gland weight, total body weight, and submandibular/sublingual gland weight by 89, 33, 30, and 32% (p < 0.01), respectively, while SM flow rate was not altered significantly. At 2 months, these parameters were reduced by 59, 37, 31, and 37%, respectively, and the SM flow rate was reduced by 39% (p < 0.01).

RESULTS

Pilocarpine, a muscarinsic agonist which, albeit its efficacy as a salivary watery secretion stimulator, causes only limited degranulation, did not protect significantly any of the reduced parameters at either term. In contrast, cyclocytidine, an adrenergic agonist that is a very potent salivary degranulating agent, protected the P against the weight loss at 4 days and 2 months, and against the flow rate reduction at 2 months. The P weight and flow rate were protected to the extent that their values were not significantly different than those of the nonirradiated controls. Cyclocytidine also partially protected against the body weight reduction at 2 months. Our results emphasize the importance of secretion granules as mediatory agents in IR-induced P damage, and more so at the extended term. The demonstrated protective role of adrenergic agonists against IR damage to the P may be of importance in the clinical setting.

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.

Preliminary results of a pilot study using WR-2721 before fractionated irradiation of the head and neck to reduce salivary gland dysfunction

PURPOSE

Based on in vivo evidence of radioprotection of the salivary glands using WR-2721, a pilot study was undertaken to determine the feasibility, toxicity, and salivary function of patients receiving WR-2721, while undergoing radiation therapy to the head and neck.

METHODS AND MATERIALS

Patients undergoing radiation therapy for cancer of the head and neck were eligible if the major salivary glands received more than 45 Gy. WR-2721 was administered over 6 min IV, 10-15 min prior to each dose of radiation five times per week. Saliva was collected and measured prior to radiation therapy, weekly during radiation therapy, 1 month postradiation therapy, and every 3 months thereafter. Flow rates of unstimulated whole saliva, stimulated whole saliva, and stimulated parotid saliva were measured using standard techniques. 99mTc salivary scintiscans were performed prior to radiation therapy, 1 month postradiation therapy and every 3 months thereafter. Nine patients are presently enrolled on the first dose level (100 mg/m2) of this study. Eight completed per protocol, two with minor decreases of total WR-2721 doses. Two patients progressed with distant metastases soon after completion of therapy. All available data are included in the analysis. Median follow-up for all patients is 18 months.

RESULTS

Flow rates of unstimulated whole saliva decreased significantly during radiation therapy reaching 5.6% of baseline at 9 months postradiation therapy, subsequently recovering to 20% of baseline, then remaining stable over time. Stimulated whole salivary flow rate similarly decreased during radiation therapy and reached its nadir (11% of baseline) at 3 months postradiation therapy, improving to 27% of baseline by 2 years. The stimulated parotid flow rate decreased during radiation therapy to 1.4% of pretreatment levels. Significant recovery took place 6 months postradiation therapy and by 18 months values had recovered to 54% of baseline. 99mTc salivary scintiscans confirmed this rebound of parotid function postradiation therapy. Toxicity was minimal with the exception of one patient who received only 27% of the planned total drug dose due to grade 3 hypotension after the eighth treatment. No recovery of salivary function has been seen in this patient; flow rates remain zero in all three areas tested 21 months after radiation.

CONCLUSIONS

Administration of WR-2721 prior to each dose of radiation was feasible and without significant toxicity at 100 mg/m2. Salivary gland function improved over time after completion of radiation, particularly the parotid. Future directions include escalation of WR-2721 dose to 200 mg/m2 and then 300 mg/m2, and a Phase III randomized trial will be undertaken once the optimal dose is established.

Influence on rabbit submandibular gland injury by stimulation or inhibition of gland function during irradiation. Histology and morphometry after 15 gray

The loss of salivary gland function after a single dose of 15 Gy was correlated to loss of gland weight and degeneration of seromucous acini and serous tubules at 10 months postirradiation. The serous tubules were degranulated rather early, but regenerated after some months in an abnormal way as adenomatous structures. Striated ducts were mainly unaffected by irradiation. Arterioles showed slight to moderate narrowing of the lumina. There was an increased amount of plasma cells in the gland lobules at 10 months postirradiation. Histologic and morphometric criteria and changes in gland weight showed less pronounced radiation injury in glands irradiated during inhibition of the gland function by biperiden (Akineton) compared to glands irradiated during stimulation of the gland function by pilocarpine. This finding may offer a clinically important means to reduce salivary gland dysfunction after radiation treatment of tumors in the head and neck regions.

Radioprotection of minipig salivary glands by orciprenaline-carbachol. An ultrastructural and semiquantitative light microscopic study

Parotid and submandibular glands of miniature pigs were exposed to 36 Gy X-irradiation given as 6 x 6 Gy in 3 weeks. Half of the animals received orciprenaline and carbachol before each dose. The effects were analysed 6 months later by light and electron microscopy. Ultrastructural examination showed less change in the pretreated glands. Semi-quantitative light microscopic data confirmed the significance of the differences. Acinar cells of both glands were significantly more numerous (P less than 0.01) and the cells were better preserved (P less than 0.01) in the pretreated group. The effect was more pronounced in the parotid gland, which appeared almost normal. Intercalated ducts of the parotid glands (P less than 0.01) and striated ducts of the submandibular glands (P less than 0.05) showed less change in pretreated animals. The findings confirm the radioprotective effect of pharmacologically induced degranulation of acinar cells. The biological effects of the radiation schedule (cumulative radiation effect value 18.76) as well as the dosage of orciprenaline and carbachol are within the normal range of medical treatment. Similar results may be expected from future studies in man.

Iatrogenic causes of salivary gland dysfunction

Saliva is important for maintaining oral health and function. There are instances when medical therapy is intended to decrease salivary flow, such as during general anesthesia, but most instances of iatrogenic salivary gland dysfunction represent untoward or unavoidable side-effects. The clinical expression of the salivary dysfunction can range from very minor transient alteration in saliva flow to a total loss of salivary function. The most common forms of therapy that interfere with salivation are drug therapies, cancer therapies (radiation or chemotherapy), and surgical therapy. These therapies can affect salivation by a number of different mechanisms that include: disruption of autonomic nerve function related to salivation, interference with acinar or ductal cell functions related to salivation, cytotoxicity, indirect effects (vasoconstriction/dilation, fluid and electrolyte balance, etc.), and physical trauma to salivary glands and nerves. A wide variety of drugs is capable of increasing or decreasing salivary flow by mimicking autonomic nervous system actions or by directly acting on cellular processes necessary for salivation: drugs can also indirectly affect salivation by altering fluid and electrolyte balance or by affecting blood flow to the glands. Ionizing radiation can cause permanent damage to salivary glands, damage that is manifest as acinar cell destruction with subsequent atrophy and fibrosis of the glands. Cancer chemotherapy can cause changes in salivation, but the changes are usually much less severe and only transient. Finally, surgical and traumatic injuries interfere with salivation because of either disruption of gland innervation or gross physical damage (or removal) of glandular tissue (including ducts).