RTOG 9704 a phase III study of adjuvant pre and post chemoradiation (CRT) 5-FU vs. gemcitabine (G) for resected pancreatic adenocarcinoma

4007

Background: RTOG 9704 was designed to determine if the addition of G to postoperative adjuvant 5-FU CRT improved survival for patients(pts) with resected pancreatic adenocarcinoma. Methods: In this Intergroup trial involving RTOG, ECOG and SWOG, pts post gross total resection of pancreatic adenocarcinoma (path stage T1 - 4, N0 - 1, M0) were randomized to receive pre and post CRT 5-FU vs pre and post CRT G. 5-FU = continuous (CI) at 250 mg/m2/day. G = 1000 mg/m2 IV weekly. Both were given over 3 weeks pre and 12 weeks post - CRT. CRT = 50.4 Gy 1.8 Gy/fx/day with CI 5-FU, 250 mg/m2/day during RT for all pts. Pts were stratified by nodal status (uninvolved vs involved), primary tumor diameter ( < 3 cm vs ≥ 3 cm) and surgical margins (negative vs positive vs unknown). Survival was the primary endpoint with an original targeted accrual of 330 pts. Rapid enrollment allowed study amendment for increased targeted accrual to add survival among pts with lesions of the pancreatic head as a primary, prospective endpoint. Results: From 7/98 - 7/02, 538 pts were entered; 442 were eligible and analyzable. Major reasons for patient ineligibility were serum not sent for CA-19–9 analysis (n=22) and treatment starting > 8 weeks post surgery (n=19). Treatment arms were well balanced except for T-stage (T3/4 > for G, p=0.013). Pts with pancreatic head tumors(n=380) experienced significantly improved survival, with median and 3-year survival of 18.8 months and 31% respectively for the G arm vs. 16.7 months and 21% for the 5-FU arm (p=0.047; HR=0.79, CI=0.63–0.99). When analysis was inclusive of pts with body/tail tumors(n=442) no significant difference in survival was found (p=0.20). No significant difference in non-hematologic grade ≥ 3 toxicity was seen. The grade 4 hematologic toxicity rate was 14% in the G arm and 2% in the 5-FU arm (p<0.0001) without difference in febrile neutropenia/infection. The ability to complete chemotherapy (86%, 5-FU vs. 90%, G) and RT (85%, 5-FU vs. 88%, G) as per study was similar. Conclusions: The addition of G to postoperative adjuvant 5-FU CRT significantly improves survival in pts with pancreatic head adenocarcinoma.

No significant financial relationships to disclose.

Background and framework for ILSI's collaborative evaluation program on alternative models for carcinogenicity assessment. International Life Sciences Institute

The willingness of the agencies involved in the regulation of pharmaceuticals to accept data from newly proposed models for carcinogenicity testing (eg, transgenic animals, neonatal rodent models, initiation-promotion models) has stimulated international interest in gaining experience and a greater understanding of the strengths and limitations of the specific models. Over a 4-year period, the International Life Sciences Institute (ILSI) Health and Environmental Science Institute (HESI) has coordinated a large-scale collaborative research program to help to better characterize the responsiveness of several models proposed for use in carcinogenicity assessment. The overall objective of this partnership among industry, government, and academic scientists was to evaluate the ability of these new models to provide useful information for human cancer risk assessment. This research program reflected a commitment of nearly US$35 million by over 50 industrial, govemment, and academic laboratories from the United States, Europe, and Japan. Evaluation of the models required the development of standardized protocols to allow reproducibility and comparability of data obtained across multiple laboratories. Test compounds were selected on the basis of mechanistically meaningful carcinogenic activity or noncarcinogenicity in the rodent bioassay as well as humans. Criteria were established for dose selection, pathology review, quality control, and for evaluation of study outcome. The database from these studies represents an important contribution to the future application of new models for human cancer risk assessment. Beyond the data, the collaborative process by which the models were evaluated may also represent a prototype for assessing new methods in the future.

Phase II trial of oral beta-all trans-retinoic acid in hepatocellular carcinoma (SWOG 9157)

Twenty-nine chemotherapy-naive patients with primary hepatocellular carcinoma were treated with oral beta-all trans-retinoic acid (retinoic acid, TRA 50 mg/m2 t.i.d.) on a 3-week on/one week off schedule until progression or grade 3 or 4 toxicity. Eligibility requirements allowed abnormal liver function tests as long as the creatinine and bilirubin levels were normal. No responses were seen and the median survival was four months. Grade 3 side effects occurred in II patients and grade 4 in four and included a wide range of toxicities. The results indicate that oral TRA is ineffective against primary hepatocellular carcinoma and suggest that dose-modification of this retinoid may be required in patients with significant malignant hepatic involvement.

Inadequate documentation and resection for gastric cancer in the United States: a preliminary report

Patients entered into Southwest Oncology Group gastric adjuvant protocol INT 0016 (SWOG 9008) after a "curative" gastric resection were assessed to determine practice patterns of more than 300 surgeons nationwide who performed "curative" gastric resections for 453 gastric cancer patients. The most common gastric resection performed was distal in 256 patients, proximal in 118, and total in 79. Extragastric organs resected were omentum (285), spleen (59), pancreas (18), and bowel (17). The extent of lymphadenectomy as staged by Japanese rules was 246 (54.2%) D0 resections, 173 (38.1%) D1 resections, 28 (6.2%) D2 resections, and 7 (1.5%) D3 resections. Staging of the cancer was poorly documented, with no statement made regarding the status of the primary cancer in 6 per cent, liver in 10 per cent, lymph nodes in 17 per cent, and omentum in 17 per cent. The greater the lymph node clearance, the greater the chance of resecting to a level of negative lymphatics, given that 45 per cent of nodes were involved when 10 or less were removed, whereas only 17 per cent were positive when more than 40 were cleared. The lack of adequate clearance of lymph nodes and poor documentation of tumor stage suggests that a more regimented surgical approach to this uncommon cancer is required.

Evaluation of the carcinogenic potential of pharmaceuticals. Opportunities arising from the International Conference on Harmonisation

The evaluation of the carcinogenic potential of pharmaceuticals is currently undergoing dramatic changes. For the past 25 years the regulatory expectation for agents intended for long term use has been that lifespan studies (usually lasting 2 years) in 2 rodent species be conducted. These studies take at least 3 years to plan, execute and interpret, and use over 1200 animals. It is now recognised that the quality of the information obtained from these studies is unreliable for prediction of carcinogenic risk to humans. Over the past 4 years, the International Conference on Harmonisation (ICH) has recommended changes in approaches to assessing the carcinogenic potential of pharmaceuticals. In future, only one long term rodent study will be routinely required (usually in rats), provided this is complemented with a short or medium term test in one of the emerging new models for carcinogenicity, such as transgenic mice or newborn mice. However, the relevance of these new models to human cancer and their use in risk assessment is still largely unknown and this situation must be kept under review as knowledge accumulates. A long term study in a second rodent species is still an option. Dose selection has also been improved inasmuch as there are now several alternatives to the use of the maximum tolerated dose (MTD). In the past, the use of the MTD, when the normal homeostasis of the test animals is disturbed, has been considered one of the major problems with the rodent carcinogenicity bioassay. However, one of the alternative end-points to the use of the MTD, i.e. the comparison of plasma concentrations in rodents and humans, must be viewed with caution. While this may contribute to limiting the high dose level for agents of very low toxicity, the concept should not be interpreted as signifying that plasma concentrations provide a sound basis for comparing the carcinogenic activity of agents in different species. Recognition of the 4 properties (genotoxicity, immunosuppression, steroid hormonal activity and long term tissue damage), at least one of which is associated with each of the pharmaceuticals known to be carcinogenic to humans, should focus more attention on a search for these properties in patients. Absence of these properties at clinically relevant dose levels indicates that a pharmaceutical is highly unlikely to be carcinogenic to humans.

Home from home: residents' opinions of nursing homes and long-stay wards

OBJECTIVE

To compare the levels of satisfaction expressed by residents of nursing homes with those of patients in geriatric long-stay wards.

DESIGN

A structured satisfaction questionnaire containing 37 closed and two open questions was used to elicit responses from residents of nursing homes in the former South West Thames Regional Health Authority area. This was compared with a similar survey using the same questionnaire among patients in geriatric long-stay wards surveyed in 1989.

SETTING

respondents came from a sample of nursing homes chosen to be representative of both size and geographical location. Nursing homes were stratified by number of beds (1-19, 20-29, 30+) and clustered by location (to reflect the urban, semi-rural and coastal nature of the region).

SUBJECTS

A random sample was drawn from each grouping (size and location) to yield a resident sample of 850 in 36 nursing homes. This figure was similar to the number of patients (808) in geriatric long-staywards surveyed in 1989. All eligible nursing home patients were assessed for physical dependency. Mental confusion was ascertained by the Abbreviated Mental Test Score (AMTS). Patients who scored three or less on the AMTS (indicative of severe confusion) or had dysphasia, profound deafness or concurrent serious illness were excluded from further study.

RESULTS

377 nursing home residents were able to complete the questionnaire and their answers were compared with those of 291 long-stay geriatric patients. The responses to the five themes--relations with staff, autonomy, amenities, privacy and social environment-show some minor differences between the two groups but what is more noticeable is the similarity of their views. This is important as much social policy assumes that the more 'homely' atmosphere of the nursing home should elicit higher levels of satisfaction than the 'institutional' setting of the hospital ward.

CONCLUSION

We conclude that the difference between nursing homes and hospital wards in terms of their institutionalizing capacities is not as profound as policy-makers believe.

Combined in vitro and in vivo T lymphocyte depletion for the control of graft-versus-host disease following haploidentical marrow transplant

Most patients requiring allogeneic bone marrow transplantation (BMT) lack a human leukocyte antigen genotypically identical sibling and require an alternative donor. This carries an increased risk of graft failure and acute graft-versus-host disease (GVHD). We sought to overcome these problems with transplants by using grafts obtained from the most readily available source: the haploidentical, partially mismatched, related donor. This study of 40 patients used a novel approach combining in vitro and in vivo T cell depletion with T lymphocyte targeted monoclonal antibodies (mAb) and intensified conditioning therapy, including fractionated total body irradiation before etoposide, cytoside arabinoside, cyclophosphamide, and methylprednisolone. Grafts were treated with T10B9.1A-31 mAb, directed against the alpha-beta heterodimer of the T cell receptor, and rabbit complement. In vivo depletion was attempted with an anti-CD5 mAb-Ricin A-chain (H65-RTA) immunotoxin (IT). Study patients were compared with a historical control group of 17 patients not given H65-RTA. Rates of engraftment were not significantly different (93% vs. 100%, P=0.12), although patients receiving IT engrafted more rapidly. The incidence of > grade I GVHD was significantly lower in the study group (36% vs. 100%, P=0.0001), as well as for severe grade III-IV GVHD (19% vs. 92%, P=0.0001). Five-year survival tended to be improved in the study group (40% vs. 18%, P=0.21). Transplant from haploidentical family members is indicated for patients without a matched sibling in whom allogeneic BMT offers the best opportunity to achieve cure.

Toxicokinetic and mechanistic considerations in the interpretation of the rodent bioassay

When chemicals that are nongenotoxic in conventional assays produce increases in tumor incidence in rodents in chronic bioassays, the determination of the significance of these data for human safety is a challenging task. An important first step in this process is consideration of available data on the mechanism of action and biological properties of the chemical as well as pharmacokinetic and metabolism data in the species showing the response. In recent years, there has been an increase in the understanding of so-called "secondary mechanisms" of carcinogenesis (e.g., thyroid tumors in rats following exposure to enzyme inducers). Application of these data may assist in determination of human risk. There are 2 important questions that will be explored and developed: Are there biological effects produced in the test species that could explain the increase in tumor incidence, and will these effects be reproduced in humans? What is the exposure to the chemical that is associated with the increase in tumors, and how does this relate to exposure in humans?

Leydig cell hyperplasia and adenomas in mice treated with finasteride, a 5 alpha-reductase inhibitor: a possible mechanism

Finasteride is a selective inhibitor of the enzyme 5 alpha-reductase which is responsible for the conversion of testosterone (T) to dihydrotestosterone (DHT). Finasteride is indicated for the treatment of benign prostatic hyperplasia in man (approximately 0.1 mg/kg/day). The effect of long-term treatment was studied in mice given high doses (2.5, 25, and 250 mg/kg/day) of finasteride for 83 weeks. In finasteride-treated mice, increased incidences of testicular Leydig cell hyperplasia (52% compared to 24% in control group) at doses equal to or greater than 25 mg/kg/day and Leydig cell adenomas (32% compared to 0.5% in control group) at 250 mg/kg/day were observed. There were no drug-related effects on the seminiferous tubules. Since luteinizing hormone (LH) is a trophic hormone for Leydig cells, short-term studies (5 to 14 weeks) were done to investigate the relationship between Leydig cell hyperplasia and serum LH levels in finasteride-treated mice. In these studies, there was a positive correlation between the drug-related increased incidence of Leydig cell hyperplasia and a statistically significant (p < or = 0.05) increase in serum LH levels in finasteride-treated (250 mg/kg/day) mice. Furthermore, studies in castrated male mice showed that the suppression of serum LH levels by T is reversible by inhibition of conversion of T to DHT with finasteride (250 mg/kg/day), supporting the hypothesis that DHT is involved in the regulation of LH release in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Amonafide treatment of refractory esophageal cancer. A Southwest Oncology Group study

Amonafide, a synthetic benzisoquinolinedione, was evaluated for treatment of squamous esophageal cancer. Eleven men and 5 women were eligible with a median performance status of 1 and median age of 63 years. Six had no prior treatment. All patients had measurable disease. Therapy consisted of amonafide 300 mg/m2d days 1-5 every 21 days. Thirty-five courses of therapy were delivered. The median number of courses received was two. Sixteen patients are evaluable for toxicity. Thirteen are evaluable for response. Toxicity was severe. Seven patients were hospitalized for toxicity. Six patients had grade IV granulocytopenia; two, grade IV thrombocytopenia. Angioedema developed in one patient; severe exfoliative dermatitis in another. A single partial response, with the decrease in size a supraclavicular node, was noted in a previously untreated patient. Amonafide, in this dose and schedule, is associated with occasionally severe toxicity precluding its likely use in squamous cell esophageal carcinoma.

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase induce reductase accumulation and altered lamellar bodies in rat forestomach keratinocytes

Lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and a potent hypocholesterolemic agent, induces a hyperplastic thickening of the rat forestomach mucosa after oral administration of its active form, a hydroxyacid. We studied the effects of lovastatin on the intracellular accumulation of HMG-CoA reductase immunostaining and the accompanying morphological changes in rat forestomach keratinocytes by immunofluorescence microscopy and transmission electron microscopy (TEM). Administration of lovastatin hydroxyacid induced increases in HMG-CoA reductase levels within forestomach keratinocytes that were dose and time dependent and reversible. The adjacent glandular stomach epithelium did not exhibit induction of reductase. A pharmacologically inactive epimer of lovastatin hydroxyacid did not increase keratinocyte reductase accumulation, and lovastatin lactone induced minimal forestomach reductase. TEM of forestomachs from rats given lovastatin hydroxyacid demonstrated profound alterations in epidermal lamellar bodies (organelles that transport lipids and steroids to the intercellular spaces of the stratum corneum). Treated cells lacked internal lipid lamellae and failed to secrete sheets of lipid material into the intercellular spaces of the stratum corneum. We hypothesize that sustained inhibition of HMG-CoA reductase in rat forestomach keratinocytes induces accumulation of HMG-CoA reductase and hyperplasia by inhibiting sterol synthesis, assembly of lamellar bodies, and formation of intercellular lipid sheets.

Studies on the effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on the rodent forestomach

A novel class of hypocholesterolaemic agents, HMG CoA reductase inhibitors, was shown to cause mucosal thickening in the rodent (mouse and rat) forestomach after subacute/subchronic oral administration. These changes were characterized histologically by acanthosis and hyperkeratosis of the squamous epithelium with submucosal oedema and occasionally cellular infiltration. This drug-induced hyperplastic response was both dose and time dependent, did not occur after subcutaneous administration, and was confined entirely to the rodent forestomach (not observed in any other area of the gastro-intestinal tract). The forestomach hyperplastic response correlated with the pharmacological potency of HMG CoA reductase inhibitors of similar structure (observed to varying degrees with all HMG CoA reductase inhibitors examined to date).

HMG-CoA reductase inhibitor-induced myopathy in the rat: cyclosporine A interaction and mechanism studies

Recent clinical evidence indicates a potential for skeletal muscle toxicity after therapy with HMG-CoA reductase inhibitors (HMGRIs) in man. Although the incidence of drug-induced skeletal muscle toxicity is very low (0.1-0.2%) with monotherapy, it may increase following concomitant drug therapy with the immunosuppressant, cyclosporine A (CsA), and possibly with certain other hypolipidemic agents. In the Sprague-Dawley rat, very high, pharmacologically comparable dosages (150-1200 mg/kg/day) of structurally similar HMGRIs (lovastatin, simvastatin, pravastatin and L-647, 318) produced dose-related increases in the incidence and severity of skeletal muscle degeneration. Physical signs included inappetence, decreased activity, loss of body weight, localized alopecia and mortality. To evaluate the interaction between HMGRIs and CsA, a rat model of CsA-induced cholestasis was developed. In this 2-week model, the skeletal muscle toxicity of the HMGRIs was clearly potentiated by CsA (10 mg/kg/day). Doses of HMGRIs which did not produce skeletal muscle toxicity when given alone caused between 75 and 100% incidence of myopathy (very slight to marked skeletal muscle degeneration) when CsA was coadministered. Typical light microscopic changes included myofiber necrosis with interstitial edema and inflammatory infiltration in areas of acute injury. Histochemical characterization of the muscle lesion indicated that type 2B fibers (primarily glycolytic white fibers) were most sensitive to this toxicity but that, with prolonged administration, all fiber types were ultimately affected. Results of pharmacokinetic studies in rats treated with various HMGRIs +/- CsA indicated that coadministration of CsA alters the disposition of these compounds, resulting in increased systemic exposure (e.g., increased area under the plasma drug concentration vs. time curve-AUC) and consequent (up to 13-fold) increases in skeletal muscle drug levels. Evaluation of the potential interaction between the HMGRI, lovastatin and CsA at the level of hepatic microsomal metabolism indicated that CsA did not inhibit the metabolism of lovastatin in isolated microsomes from female rats. In light of the above findings, it appears that HMGRI-induced myopathy is a class effect in the rat, which is potentiated by CsA as the result of altered clearance and resultant increased tissue exposure. Cholestasis associated with CsA and HMGRIs may form the basis for decreased elimination and the resultant elevated systemic exposure. Furthermore, this toxicity is muscle fiber-selective and may be associated with impaired skeletal muscle energy metabolism.

Studies on the mechanism of simvastatin-induced thyroid hypertrophy and follicular cell adenoma in the rat

Female Sprague-Dawley rats were treated with either simvastatin (a novel competitive inhibitor of HMG CoA reductase) or phenobarbital (positive control) to ascertain the possible relationship between the effects of simvastatin on hepatic metabolism and the thyroid hypertrophy and follicular cell adenomas which it produces in this strain of rat. The test compounds were administered orally at doses of 100 mg/kg (divided doses at 50 mg/kg, b.i.d.). (This dose of simvastatin represents approximately 250 times the human dose.) After 5 weeks of treatment, either simvastatin or phenobarbital produced significant increases (35% and 39% above control, respectively) in serum thyroid stimulating hormone (TSH), a significant increase (39% and 120% above control, respectively) in the systemic clearance of 125I-thyroxine, and slight decreases in serum thyroxine levels. Statistically significant increases in liver and thyroid weights were associated with phenobarbital treatment. With simvastatin, increased liver weights occurred. At the microscopic level, thyroid hypertrophy was observed in all phenobarbital-treated rats and to a lesser degree in most simvastatin-treated animals. Simvastatin did not markedly alter liver microsomal enzyme activities with the exception of the anticipated induction of HMG CoA reductase (which increased approximately 4.4-fold). Conversely, phenobarbital produced large increases in liver microsomal enzymes, including glucuronosyl transferase, but did not affect the activity of HMG CoA reductase. Therefore, the increased clearance of thyroxine in simvastatin-treated female rats was not associated with enzyme induction but may have been related to the increase in functional liver mass produced by this compound at this dose.(ABSTRACT TRUNCATED AT 250 WORDS)

The toxicity of a fluorinated-biphenyl HMG-CoA reductase inhibitor in beagle dogs

L-645, 164, a potent inhibitor of hydroxymethylglutarylcoenzyme A (HMG-CoA) reductase, is a structurally unique, synthetic monofluorinated-biphenyl that was administered to beagle dogs at dosages of 2, 10, or 50 mg/kg/day for 14 weeks to evaluate its toxic potential. Previously tested HMG-CoA reductase inhibitors from this laboratory have either been semisynthetic or fermentation-derived products containing a hexahydronaphthalene ring structure (i.e., lovastatin and simvastatin). Administration of L-645, 164 produced a significant spectrum of lesions, some of which have been previously associated with compounds of this pharmacological class, while others were unique to this monofluorinated-biphenyl inhibitor. Subcapsular lenticular opacities were produced in six of eight of the dogs receiving 50 mg/kg/day of L-645, 164 within 8 weeks of dosing. One dog receiving this dosage level experienced increases in serum alanine aminotransferase activity to levels 10 times those in concurrent control dogs. Light and electron microscopy of a wedge biopsy obtained within 3 days of this transaminase elevation failed to reveal any significant changes and the elevation resolved spontaneously despite continued drug administration. Lesions of the optic nerve and acoustic-vestibular tract and trapezoid decussation were observed in several dogs receiving 50 mg/kg/day. In addition, similar changes were observed in the optic tract in several of the dogs receiving 50 mg/kg/day and in one dog receiving 2 mg/kg/day of L-645,164. These were unique to L-645,164 and have not been observed after the administration of other HMG-CoA reductase inhibitors in this laboratory. Optic tract changes were generally mild, consisting of small to medium vacuoles without apparent myelin loss. Lesions in the other areas ranged from very slight to prominent vacuolation. No clinical signs were observed. Peak plasma drug levels of L-645,164 at 50 mg/kg were greater than 5 micrograms/ml, about one order of magnitude greater than those attained after administration of pharmacologically equipotent doses of lovastatin and simvastatin. These findings support previous observations that HMG-CoA reductase inhibitors producing high plasma drug levels are associated with a significant degree of systemic toxicity. In addition, the drug-induced CNS lesions attributed to L-645,164 appear also to be related to its chemical structure since similar lesions have not been observed after the administration of other structurally unrelated HMG-CoA reductase inhibitors that produce high plasma drug concentrations and comparable degrees of serum cholesterol lowering.

A phase II multi-institutional trial of low-dose N-(phosphonacetyl)-L-aspartate and high-dose 5-fluorouracil as a short-term infusion in the treatment of adenocarcinoma of the pancreas. A Southwest Oncology Group study

Adenocarcinoma of the pancreas is a highly lethal malignancy and chemotherapy has had little impact on the natural history of this disease. PALA, used to potentiate 5-fluorouracil (5-FU), has been shown to have synergy in vivo and in vitro. Twenty-seven patients were treated with an intravenous push dose of PALA (250 mg/m2) followed 24 hours later with a 24-hour infusion of 5-FU (2600 mg/m2). This regimen was repeated weekly. There was one partial response of 21 eligible patients with an estimated response rate of 5%. Toxicity was severe with one toxic death and four patients experiencing Grade 4 toxicity. 5-Fluorouracil and PALA, given in the schedule described, do not appear to be effective against adenocarcinoma of the pancreas.

Decreased fertility in male rats administered the 5 alpha-reductase inhibitor, finasteride, is due to deficits in copulatory plug formation

Oral administration of 80 mg/kg/day of finasteride, a potent specific inhibitor of 5 alpha-reductase, to sexually mature male Sprague-Dawley rats for 24 to 38 weeks caused an approximate 30% to 40% decrease in fertility. There were no effects on mating indices or implants per pregnant female. From the mating trials, a selected group of treated males with poor reproductive performance was compared to a selected group of control males with good reproductive performance. Observed matings showed no qualitative effects on mating behavior or ejaculation. However, finasteride-treated males did not form or formed small and improperly positioned copulatory plugs, which are required in rats to transport sperm into the uterus. Intrauterine insemination of epididymal sperm from males that were nonfertile by natural mating resulted in similar numbers of embryos and unfertilized oocytes recovered from controls and finasteride-treated males, confirming that there was no effect of finasteride on the ability of sperm to fertilize. Decreased fertility of finasteride-treated males was due to failure to form copulatory plugs and is related to decreased weight of seminal vesicles and prostate, an expected pharmacologic effect. Testes weight was unaffected. Decreased fertility in male rats after finasteride administration is considered a species specific effect. The mechanism of the decrease in rats is not likely to be relevant to species that do not form copulatory plugs.

Treatment of non-small-cell lung cancer with vinblastine and very high-dose cisplatin. A Southwest Oncology Group study

Suggestions of a dose-response effect for cisplatin in non-small-cell lung cancer have contributed to the development of very high-dose cisplatin regimens (200 mg/m2 per cycle). We treated 53 eligible patients with metastatic or recurrent non-small-cell lung cancer with a combination of 100 mg/m2 cisplatin and 4 mg/m2 vinblastine, each given on days 1 and 8 of a 28-day cycle. We observed no complete response and 4 partial responses (8%). Median survival was 6 months. Toxicities of grade III or greater included leukopenia (11 cases), nausea/vomiting (6 cases), thrombocytopenia (2 cases), anemia (2 cases), and elevation of transaminase (1 case). Neurotoxicity has been reported to be a major problem in several other very high-dose cisplatin regimens. The low level of neurotoxicity observed in this study may be attributable to the median cumulative cisplatin dose of less than 600 mg/m2. This vinblastine/very high-dose cisplatin regimen showed minor activity against non-small-cell lung cancer. The level of activity did not surpass that of standard-dose (100 mg/m2 per cycle) cisplatin-containing regimens.

Reversible decreases of fertility in male Sprague-Dawley rats treated orally with finasteride, a 5 alpha-reductase inhibitor

Finasteride, a 5 alpha-reductase inhibitor, was investigated for its effects on fertility in male rats as part of its preclinical safety assessment. Studies were initiated when the male Sprague-Dawley rats were either young (4 to 6 weeks old) or mature (15 weeks old). Treatment duration ranged from 6 to 32 weeks. Each male was cohabited with two untreated females at various periods during and after treatment. Litter parameters were evaluated on either day 14 or 20 of gestation. Males were necropsied at the end of treatment or 7 to 11 weeks following the end of treatment. The major findings of these studies were that 1) young rats given 20 to 80 mg/kg/day of finasteride first showed mild to moderate decreases in fertility after 12 weeks of treatment, whereas mature males (given only 80 mg/kg/day) did not show a similar decrease until 24 weeks of treatment, 2) fewer copulatory plugs and atrophy of prostates and seminal vesicles were associated with finasteride treatment, 3) the decreased fertility was only partial (ie, fertility index did not decrease below 48% of control in any study) and was not due to decreases in mating, 4) formation of copulatory plugs, organ weights, and fertility returned to normal levels after at least 6 weeks of drug withdrawal, and 5) the testes showed no histologic or weight changes that would explain the effect on fertility. These results show that the decreased fertility in male rats was associated with finasteride-induced inhibition of accessory gland secretions, an expected pharmacologic effect.

External genitalia abnormalities in male rats exposed in utero to finasteride, a 5 alpha-reductase inhibitor

A series of studies was conducted to determine the developmental toxicity of the 5 alpha-reductase inhibitor finasteride (MK-0906) in rats. This compound was administered orally once daily to pregnant rats during various extended treatment periods during gestation. F1 offspring were evaluated on Day 20 of gestation as well as postnatally through mating to produce an F2 generation. MK-0906 treatment induced dosage-related incidences of hypospadias (penischisis) in male offspring with a threshold dosage level near 0.1 mg/kg/day and a 100% effect level of 100 mg/kg/day (with dosing through Day 20 of gestation). MK-0906 also caused decreased anogenital distance in male offspring. The dosage response for this effect (ranging from a 4.2% decrease at 0.003 mg/kg/day to a 38% decrease at 100 mg/kg/day) was more shallow than that for hypospadias. The decreases in anogenital distance were at least partially reversible postnatally with essentially complete recovery at dosages up to 0.1 mg/kg/day. There was also a dosage-related, temporary induction of nipples in F1 males. All of these effects were apparent following treatment on Days 6 through 17 of gestation but were more pronounced when dosing extended to Day 20 of gestation. Slight maternal toxicity consisting of minor decreases in body weight gain occurred only at dosages of 3 mg/kg/day and higher, indicating the selective nature of the developmental toxicity. The 5 alpha-reductase enzyme located in the rat fetal genital tubercle was studied in vitro and compared to that in the adult ventral prostate. The values for Km, Vmax, and IC50 for inhibition by MK-0906 were similar in the two tissues, suggesting that the enzymatic proteins in the genital tubercle and ventral prostate may be similar.

Maternotoxicity and fetotoxicity of an angiotensin-converting enzyme inhibitor, enalapril, in rabbits

When enalapril, an angiotensin-converting enzyme (ACE) inhibitor, was orally administered to inseminated rabbits at dosages of 0.1 to 30 mg/kg/day for 13 days in a range-finding study, nephrotoxicity, as measured by elevated serum urea nitrogen concentrations, occurred at 1 mg/kg/day and higher dosages and significant (p less than or equal to 0.05) increases in fetal wastage were observed at dosages as low as 3 mg/kg/day. Saline supplementation during treatment prevented this rise in urea nitrogen. Fetal wastage was significantly (p less than or equal to 0.05) increased in the absence of maternotoxicity when saline-supplemented females were treated with enalapril at 30 mg/kg/day. A developmental toxicity study of enalapril in saline-supplemented rabbits produced no evidence of teratogenicity at 3, 10, and 30 mg/kg/day. The period of sensitivity of fetuses to the toxic effects of enalapril was found to be limited to middle-to-late gestation (Gestational Days 14-27). A single oral dose of enalapril (30 mg/kg) on Day 26 of gestation resulted in 100% fetal deaths. On the basis of the work done by Broughton Pipkin et al. [1982, J. Physiol. (London) 323, 415-422] and Broughton Pipkin and Wallace (1986, Brit. J. Pharmacol. 87, 533-542), which demonstrated that the sheep fetus becomes markedly hypotensive when the dam is treated with captopril or enalapril during late pregnancy, we believe that the observed fetotoxicity of enalapril in rabbits is also due to fetal hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)

On the etiology of subcapsular lenticular opacities produced in dogs receiving HMG-CoA reductase inhibitors

The administration of high dosages of various hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors has resulted in the development of subcapsular lenticular opacities in dogs. While dogs receiving cataractogenic doses of HMG-CoA reductase inhibitors experienced profound decreases in circulating serum cholesterol concentrations (40-60% reductions in total serum cholesterol), a causal relationship between serum cholesterol lowering and cataractogenesis was not established. A strong relationship was demonstrated, however, between the systemic exposure to inhibitor (plasma drug levels) and the cataractogenic potential of the various compounds studied. Analysis of lenses from dogs chronically dosed with various HMG-CoA reductase inhibitors revealed the presence of low drug levels in the lens (less than 500 ng equivalents g-1), but no correlation was observed between the amount of drug associated with the lens after chronic treatment and cataract development. In addition, no abnormalities in cholesterol content or sterol composition were observed in clear and/or cataract containing lenses from dogs chronically dosed with HMG-CoA reductase inhibitors. The kinetics of drug appearance in the aqueous and lens cortex was assessed after doses of various HMG-CoA reductase inhibitors, and suggested somewhat higher but not statistically significant peak concentrations of inhibitor were achieved by compounds which produced a higher incidence of cataracts. These data have suggested that high doses of HMG-CoA reductase inhibitors may increase lenticular exposure to drug via the aqueous humor by producing a substantial systemic exposure to drug substance. This may result in an increased concentration of inhibitor in the outer cortical region of the lens where cholesterol synthesis is critical, thereby resulting in the development of opacities. The production of lenticular changes by a HMG-CoA reductase inhibitor of diverse chemical structure establishes, with reasonable assurance, that these lens changes are mechanism based (i.e. a product of the biochemical mechanism of action of this class of compounds). An extrapolation of these findings to patients receiving therapeutic dosages enables a favorable risk evaluation since the doses to be employed clinically are much lower and result in a far lower systemic exposure to drug substance.

High-dose cisplatin in disseminated melanoma: a comparison of two schedules

A total of 38 patients with metastatic melanoma received monthly chemotherapy with cisplatin at a dose of 200 mg/m2, per cycle; 14 received 20 mg/m2 cisplatin i.v. on days 1-5 and 24 were given 100 mg/m2 i.v. on days 1 and 8. Objective responses were seen in 2/14 treated on days 1-5 and in 5 of 22 evaluable subjects receiving cisplatin on days 1 and 8, for an overall response rate of 22%. The median survival of all patients was 6 months, with no significant difference observed between the two schedules. Severe neurotoxicity and myelosuppression were more common in patients treated on days 1-5. Two patients treated in this manner were bedridden due to neurotoxicity and four developed grade 4 leukopenia after the first cycle of chemotherapy. Only one patient treated with the divided-dose schedule became leukopenic during the first cycle, and none of the patients were debilitated by neurotoxicity. Thrombocytopenia was statistically more severe. Nausea and vomiting, fatigue, ototoxicity, and paresthesia were seen with equal frequency. Very high doses of cisplatin can be delivered with acceptable toxicity using a divided-dose schedule. As the response rate on this schedule appeared to be comparable with that achieved on the more toxic consecutive 5-day schedule, the former deserves to be tested in diseases known to show a dose response to cisplatin. However, in melanoma, administration of 200 mg/m2 per course did not appear to be associated with a markedly improved response rate, compared with cisplatin alone at "standard" doses.

Animal safety and toxicology of simvastatin and related hydroxy-methylglutaryl-coenzyme A reductase inhibitors

Simvastatin, a hydroxy-methylglutaryl-coenzyme A reductase inhibitor intended for use as a hypocholesterolemic agent, has undergone a thorough preclinical toxicology evaluation. This review describes preclinical toxicology findings associated with simvastatin administration in animals and provides the rationale for our conclusion that these changes are not indicative of potential human toxicity. Although it was not surprising to find that a potent inhibitor of this key biochemical pathway produces toxicity at high dosages in animals, none of the observed changes poses a significant risk to humans at clinical dosages. Many of the toxicities produced by high dosage levels of simvastatin in animals are directly related to the drug's biochemical mechanism of action and are the result of a profound, sustained inhibition of the target enzyme that is not anticipated at clinical dosages. Furthermore, several of the simvastatin-induced changes are species-specific responses to this agent and are not relevant to human risk assessment. Of the treatment-related changes reported for simvastatin, the development of cataracts in dogs has received considerable attention. The available data demonstrate a wide margin of safety in terms of dosage levels required to elicit this response as well as the plasma concentrations associated with the development of these ocular lesions. The data suggest that the development of lenticular opacities at clinical doses of simvastatin is highly improbable. Overall, simvastatin is highly improbable. Overall, simvastatin was well-tolerated by animals in preclinical toxicology studies, and no findings contraindicating its use in humans were identified.

Toxicity of the HMG-coenzyme A reductase inhibitor, lovastatin, to rabbits

Lovastatin, a specific inhibitor of the rate-limiting enzyme in cholesterol biosynthesis, HMG-CoA reductase, has been shown to be highly effective in lowering serum cholesterol in animals and humans and thus represents a promising approach to the treatment and prevention of cardiovascular disease. During the preclinical safety assessment of lovastatin, oral doses that were tolerated by dogs, rats and mice were found to be lethal to rabbits in subacute studies. Postmortem findings in rabbits consisted of centrilobular hepatic necrosis, frequently accompanied by renal tubular necrosis and occasionally gallbladder necrosis. The liver lesions were associated with up to 300-fold elevations in serum aspartate and alanine aminotransferase activities, whereas the kidney lesions resulted in accumulations of serum urea nitrogen and creatinine. The organ damage was preceded by a progressive decline in food consumption and loss of body weight. All histopathological and serum biochemical changes induced by lovastatin were completely prevented by coadministration of mevalonate, the product of the inhibited HMG-CoA reductase enzyme. In addition, administration of mevalonate after the onset of lovastatin-induced hepatotoxicity effectively reversed the toxicity despite continued drug treatment. These findings indicated that the toxicity of high doses of lovastatin to rabbits is a consequence of a highly exaggerated pharmacologic action in blocking mevalonate synthesis. However, supplementation of lovastatin-treated rabbits with oral doses of the major product of mevalonate metabolism, cholesterol, paradoxically enhanced the liver and kidney damage, which suggested that the toxicity of lovastatin stemmed from depletion of a nonsterol metabolite(s) of mevalonate critical for cell viability.

Preclinical evaluation of lovastatin

Administration of lovastatin to animals at high dosage levels produces a broad spectrum of toxicity. This toxicity is expected based on the critical nature of the target enzyme (HMG CoA reductase) and the magnitude of the dosage levels used. The information reviewed in this paper demonstrates that these adverse findings in animals do not predict significant risk in humans. The reason for this derives from the fact that all the available evidence suggests that the adverse effects observed are produced by an exaggeration of the desired biochemical effect of the drug at high dosage levels. The presence of clear and high no-effect doses for these toxic effects along with the fact that most of the changes observed are clearly mechanism-based (directly attributable to inhibition of mevalonate synthesis) indicate that it is unlikely that similar changes will be observed at the therapeutic dosage levels in humans. This hypothesis is supported by the extensive human safety experience described by Tobert in the following report.

Brain and optic system pathology in hypocholesterolemic dogs treated with a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase

The cholesterol lowering compound lovastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34 HMG CoA reductase), was given in nine separate experiments to normocholesterolemic dogs at rates up to 180 times the maximum therapeutic dose in man (1 mg/kg/day). Mean serum total cholesterol concentrations were reduced as much as 88% below normal. Clinical evidence of neurotoxicity occurred in up to 37% of animals given 180 mg/kg/day lovastatin for 11 or more days, especially in one laboratory where the dosing regime resulted in higher concentrations of plasma drug levels. Dogs receiving 60 mg/kg/day or less never exhibited neurologic signs. The central nervous system (CNS) of affected dogs exhibited endothelial degeneration and hemorrhagic encephalopathy. Focal extravasation of horseradish peroxidase occurred frequently (6/8) in the retrolaminar optic nerve of asymptomatic or clinically affected dogs given 180 mg/kg/day lovastatin, with endothelial degeneration and discrete optic nerve degenerative lesions interpreted as ischemic. The association between the degree of hypocholesterolemia and occurrence of clinical signs was not exact. Total brain cholesterol was similar in treated and control dogs. Hypocholesterolemic dogs had proportionally lowered serum concentrations of alpha-tocopherol, but oral supplementation of this vitamin did not prevent the neurologic syndrome. Endothelial degeneration in the CNS and optic nerve may have reflected in vitro morphologic effects of HMG CoA reductase inhibitors due to extreme inhibition of nonsterol isoprene synthesis. Retinogeniculate axonal (Wallerian-like) degeneration occurred in greater than or equal to 12% of dogs given 60 mg/kg/day or more lovastatin, with central chromatolysis of occasional retinal ganglion cells. These neuroaxonal changes may have been secondary to vascular effects, but superimposed direct neurotoxic action at the high dosage levels of lovastatin could not be excluded. There was no evidence of drug induced adverse effects in the CNS of dogs given up to 30 mg/kg/day lovastatin for 2 years.

Mechanism of action and biological profile of HMG CoA reductase inhibitors. A new therapeutic alternative

Lovastatin (MK-803, mevinolin) and simvastatin (MK-733, synvinolin), 2 highly potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors, have been heralded as breakthrough therapy for the treatment of atherosclerotic disease. This paper discusses the biochemical attributes of these HMG CoA reductase inhibitors, their structures and inhibitory properties in a variety of biological systems and presents the rationale for their therapeutic use. Not only do lovastatin and simvastatin potently inhibit cholesterol biosynthesis; they also can result in the induction of hepatic low density lipoprotein (LDL) receptors, thus increasing the catabolism of LDL-cholesterol. Lovastatin and simvastatin are the first HMG CoA reductase inhibitors to receive regulatory agency approval for marketed use. Their safety profiles are reviewed and 2 aspects of this evaluation are stressed. First, the objective in the clinical use of these inhibitors is to normalise plasma cholesterol levels in hypercholesterolaemic individuals. This contrasts with the profound reductions in cholesterol obtained when normocholesterolaemic animals are treated by the high doses of these drugs required for toxicological assessment. Second, both lovastatin and simvastatin are administered as prodrugs in their lactone forms. As lactones, they readily undergo first-pass metabolism, hepatic sequestration and hydrolysis to the active form. Consequently, lovastatin and simvastatin achieve lower plasma drug levels than do other HMG CoA reductase inhibitors in clinical development. Low plasma levels have been established as an important determinant of safety in the use of HMG CoA reductase inhibitors in both animal and human studies.

Carbapenems, a new class of beta-lactam antibiotics. Discovery and development of imipenem/cilastatin

The discovery of Streptomyces cattleya and its antibiotic product, thienamycin, has ushered in a new era of beta-lactam agents, the carbapenems. Numerous carbapenems were subsequently discovered; however, none had the potency, broad-spectrum activity, and lack of cross-resistance exhibited by thienamycin. Chemical instability encountered with thienamycin was overcome by the N-formimidoyl derivative, imipenem. Imipenem is distinguished from other beta-lactams by its outstanding activity against gram-positive organisms as well as against Enterobacteriaceae, Pseudomonas aeruginosa, and Bacteroides. However, development was hindered by extensive renal metabolism of imipenem, resulting in low urinary concentrations of antibiotic. A renal dipeptidase, dehydropeptidase-I, was responsible for hydrolyzing imipenem and other carbapenems. To counter its action, a specific inhibitor, cilastatin, was developed. Coadministered with imipenem in a one-to-one ratio, cilastatin provides prolonged, reversible blockade of imipenem metabolism, dramatically improving urinary recoveries to therapeutically significant levels. Cilastatin also contributes to the safety of imipenem, since its coadministration prevents proximal tubular necrosis which has been observed in sensitive animals receiving imipenem alone in high doses. Thus, the combination imipenem and cilastatin overcame the pharmaceutical and metabolic challenges presented by thienamycin, and allowed for the evaluation in humans of the outstanding antimicrobial activity of this new class of beta-lactam antibiotics.

Mevalonate supplementation in pregnant rats suppresses the teratogenicity of mevinolinic acid, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme a reductase

Mevinolin is a fungal metabolite, and in the hydroxyacid form, mevinolinic acid, it is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-Co A) reductase, an enzyme essential in cholesterol biosynthesis. Oral administration of 800 mg/kg/day of mevinolin to rats from days 6 through 17 of gestation produced fetal malformations of the vertebrae and ribs in 29% of the litters, and there was a treatment-related increase in the incidence of gastroschisis. Mevinolinic acid at 60 and 90 mg/kg/day also produced fetal malformations of the vertebrae and ribs, and these teratogenic manifestations were markedly suppressed by coadministration of the product of HMG-Co A reductase, mevalonic acid, at a dosage level of 500 mg/kg b.i.d. A diet supplemented with 0.5% or 1.0% cholesterol had no effect on the teratogenicity of mevinolinic acid. Teratology studies in rats with a dihydroxyheptanoic acid derivative of mevinolin, a compound 1/700 as potent as mevinolinic acid as an inhibitor of HMG-Co A reductase, and dihydromevinolinic acid, an inhibitor of this enzyme comparable in activity to mevinolinic acid, indicated that the teratogenicity of these compounds was related to their relative enzyme inhibitory activity. The dihydroxyheptanoic acid derivative was not teratogenic at doses as high as 150 mg/kg b.i.d.; in contrast, when dihydromevinolinic acid was administered at 50 and 100 mg/kg/day, its potency as a teratogenic agent was comparable to that of mevinolinic acid. These studies demonstrated that inhibitors of HMG-CoA reductase produced terata in rats and that the teratogenic effects could be antagonized by coadministration of the enzyme product, mevalonic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of breast carcinoma metastases in bone: relative merits of X-rays and skeletal scintigraphy

Of 1116 patients receiving primary treatment for breast carcinoma at the Royal Marsden Hospital since 1976, 651 had an abnormal bone scintigram either at primary diagnosis (378) or on subsequent follow-up (273) and 167 developed radiographically detectable bone metastases (21 at the time of primary diagnosis). Comparison of bone scintigrams and X-rays showed that scintigraphy was an inaccurate localiser of existing radiographic detectable metastases. If X-rays alone are used to detect bone metastases a limited examination with five plates will detect metastases with 92% accuracy. After primary surgery, routine X-ray screening for bone metastases is not necessary since it is possible to identify patients at risk on the basis of clinical examination, chest X-ray, and serum alkaline phosphatase and gamma-glutamyl transpeptidase levels.

The effect of sequential addition of the nitrosourea, chlorozotocin, to the FAM combination in advanced gastric cancer

Twenty-three patients with advanced measurable gastric cancer were treated with FAM-chlorozotocin in an attempt to demonstrate improvement in rate and duration of response over FAM (5-fluorouracil, Adriamycin and mitomycin C). Six (26%) partial responses were recorded with a median duration of two months. FAM-chlorozotocin was well tolerated with moderate myelosuppression as the major dose-limiting toxicity; the leukocyte nadir was 3.0 X 10(3)/mm3 (range, 0.9-6.0) and the platelet nadir was 100 X 10(3)/mm3 (range, 45-100). The authors were unable to find significant differences in prognostic factors such as performance status, sites of metastatic disease, intensity of therapy to account for the discrepancy in response rates between FAM (42%) and FAM-chlorozotocin (26%).

Tumorigenicity of 7,12-dimethylbenz[a]anthracene, its hydroxymethylated derivatives and selected dihydrodiols in the newborn mouse

The newborn mouse lung adenoma model has been shown to be a sensitive test for studying the tumorigenicity of bay region diol epoxides and their precursor dihydrodiols. When a total dose of 28 nmol of 7,12-dimethylbenz[a]anthracene (DMBA) or its derivatives was injected i.p. into the preweaning mice, it was found that the 3,4-dihydrodiols of both DMBA and 7-hydroxymethyl-12-methylbenz[a]anthracene caused 13.3 and 4.1 times more lung adenomas than DMBA, respectively. The mice treated with the 5,6- and 8,9-dihydrodiols of DMBA, 7-hydroxymethyl-12-methylbenz[a]anthracene and its 5,6- and 8,9- and 10,11-dihydrodiols, 7-methyl-12-hydroxymethylbenz[a]anthracene and 7,12-dihydroxymethylbenz[a]anthracene developed a level of lung adenomas/mouse less than 2-fold higher than that found in the DMSO-treated control group. Liver tumors also developed in some of the mice. The percentage of mice with liver tumors also indicated that the 3,4-dihydrodiols of both DMBA and 7-hydroxymethyl-12-methylbenz[a]anthracene were more tumorigenic than DMBA itself. These data indicate that the 3,4-dihydrodiols of both DMBA and its 7-hydroxymethyl derivative may be proximate carcinogenic metabolites of DMBA in the newborn mouse.

5-fluorouracil, Adriamycin, and mitomycin-C (FAM) chemotherapy for advanced adenocarcinoma of the pancreas

Thirty-nine patients with advanced metastatic adenocarcinoma of the pancreas were treated with a combination of 5-fluorouracil, Adriamycin, and mitomycin-C (FAM). Twenty-seven of these patients had measurable disease, and ten (37%) achieved a partial response. An additional three patients had evidence of disease stabilization. The median survival period of responding patients was 12 months, compared with 3.5 months for nonresponders (P < 0.01). The median survival period for all patients was 6 months. Moderate myelosuppression constituted the treatment-limiting toxicity. The FAM combination is an active and well-tolerated regimen for pancreatic cancer and may have an application in the management of patients with less advanced disease.