Ruth D. Davis

Pancreatic Islet Cell Tumors Produced by the Combined Action of Streptozotocin and Nicotinamide

Summary Pancreatic islet cell tumors (nesidioblastomas) were produced in 64% (18/28) of the male Holtzman rats treated with both streptozotocin and nicotinamide, while only one tumor was noted in 26 male Holtzman rats treated with streptozotocin alone, and none in rats treated with nicotinamide alone or with the streptozotocin vehicle. The majority of these neoplasms occurred in animals sacrificed 14-18 months after treatment. Hypoglycemia, intensely basophilic cytoplasmic granulation in the islet tumors, and the presence of immunoreactive insulin in tumor extracts indicate that the adenomas secreted insulin.

cis-Dichlorodiammineplatinum(II) (NSC-119 875): Preclinical toxicologic evaluation of intravenous injection in dogs, monkeys and mice

cis -Dichlorodiammineplatinum(II), a compound with antineoplastic and antimitotic activity, which inhibited the synthesis of DNA and to a lesser extent of RNA and proteins, was submitted to a preclinical pharmacologic evaluation in 16 dogs, 10 monkeys, and 120 mice. The LD50 following a single dose iv in Swiss mice was 13.4 mg/kg for males and 12.32 mg/kg for females. The minimum lethal dose for the dog was a single iv injection of 2.5 mg/kg or 5 daily consecutive injections of 0.75 mg/kg and for the monkey, 5 daily doses of 2.5 mg/kg. The treatment elicited severe morbidity within 5–17 days and the time of onset was dose related. Toxic signs included severe hemorrhagic enterocolitis, severe hypocellularity of the bone marrow and lymphoid tissues and marked renal lesions (renal tubular necrosis in the dog and nephrosis in the monkey). Dogs also showed occasional pancreatitis and monkeys myocarditis and occasional degeneration of the spermatogenic cells. Renal lesions were the most severe toxic changes in survivors and were manifested by azotemia, hypochloremia, proteinuria, appearance of urinary erythrocytes, leukocytes and decreased 24-hr excretion of lactate dehydrogenase in dogs and by protracted polyuria in monkeys. Occasional hypocalcemia also occurred. In dogs and monkeys that survived the treatment, toxicity regressed entirely within 55–124 days. Treatment affected primarily tissues with a high rate of cell division (intestines, bone marrow, lymphoid tissues and occasionally testes) and tissues known for primary excretion of the compound (intestines and kidneys).

Bleomycin-induced interstitial pneumonia in dogs

The intravenous administration of Bleomycin to 10 dogs at different dosages resulted in varying degrees of interstitial pneumonia in all cases and a lower incidence of nephrosis, foot pad excoriation and ulceration, onychoptosis, and alopecia. Pulmonary changes did not occur as a simple dose-related phenomenon. The lesions required at least 38 days to become apparent and appeared to increase in severity with time. Even at the lowest dose used (0·625 mg/kg body weight) very severe changes were seen 128 days after cessation of therapy. Morphological features of interstitial pneumonia were subpleural localization, focal mesothelial hyperplasia, marked hyperplasia and metaplasia of type II pneumocytes, fetalization of alveoli, and a pleomorphic inflammatory infiltrate. In cross-sections of lung lobes selected for histology approximately 1 to 22% of the parenchyma contained lesions. Involved areas showed marked elastosis, excess of reticular fibres, fibrosis, and increased acid mucopolysaccharides. The administration of Bleomycin produced pulmonary changes similar in many respects to those reported in busulphan-treated patients and desquamative interstitial pneumonia. The finding of interstitial pneumonia and pulmonary fibrosis in dogs treated with low doses over prolonged periods points the need to monitor pulmonary function in humans treated with Bleomycin.

Tiazofurin: A new antitumor agent

SummaryTiazofurin is an interesting drug now entering Phase I trials, with marked preclinical antitumor activity against P388 and L1210 leukemias, and the Lewis lung carcinoma. Schedule dependency favoring frequent administration has been noted.The drug has a novel mechanism of action, being metabolized to an inhibitory cofactor of inosine monophosphate dehydrogenase.Tiazofurin is widely distributed after i.v. administration exhibiting a triphasic pattern of plasma decay, with a terminal half-life of 3–16 h in the three species studied. Approximately 90% of the drug was excreted unchanged in the urine within 24 h. A significant potential for the slower release of intracellularly retained drug exists.Anticipated organ toxicities based on the studies described include myelotoxicity, hepatotoxicity and nephrotoxicity. These were mild and reversible at lower doses, and were not seen at levels corresponding to the starting doses in man. A potential for hyperuricemia exists; this should be easily controllable by the use of allopurinol, without compromising the drugs antitumor effect.Phase I trials under the sponsorship of the NCI are underway in a number of institutions.

Streptozotocin Diabetes in Monkeys and Dogs, and Its Prevention by Nicotinamide

Summary Streptozotocin produces a permanent diabetic state in monkeys and dogs which can be prevented by the use of oral or intravenous nicotinamide. A total dose that is diabetogenic in the monkey when administered by a single injection is ineffective in producing a diabetic state when administered over a 4–14 day period. This observation may have relevance in regard to the schedule employed in the treatment of malignant insulinoma in man. Rhesus monkeys observed in a persistent diabetic state for up to two years failed to demonstrate any of the known extra pancreatic complications of human diabetes mellitus. There was no evidence of renal tumor induction in these animals, as had previously been reported in rats.

The stability of l-asparaginase with respect to protein denaturants

Abstract 1. 1. Under certain conditions, l -asparaginase ( l -asparagine amidohydrolase, EC 3.5.1.1) from Escherichia coli resists denaturation by heat and acid. 2. 2. Tryptone broth protects l -asparaginase from thermal inactivation; but l -asparagine, at saturating concentrations, accelerates the thermal denaturation of the enzyme. 3. 3. It is suggested that heat might offer a valuable tool in the preliminary purification of this oncolytic enzyme. 4. 4. In view of the stability of l -asparaginase, if meaningful measurements of its substrates are to be made in the presence of the enzyme, an instantaneous inactivator should be used.

Spiromustine: a new agent entering clinical trials

SummarySpiromustine is a new alkylating agent, of interest since it was rationally designed as a lipophilic compound capable of penetrating the CNS. This lipophilicity may also enhance alkylating activity against tumors other than brain tumors.Preclinical screening has shown activity against a variety of tumors, including an intracranially implanted ependymoblastoma. Alkylating activity has been demonstrated in an intracerebral glioma in the rat. Spiromustine is a cell cycle non-specific agent. Animal pharmacology studies have shown a biphasic plasma decay curve, with hepatic metabolism and excretion, an enterohepatic circulation of metabolites, and approximately 50% renal excretion of unchanged drug. Toxicology studies in mice, rats and dogs showed that dose-related myelosuppression, and neurotoxicity predominated; other organ toxicities were mild.Spiromustine is currently entering Phase I clinical trials on a variety of schedules.

Pathological effects of bleomycin on the skin of dogs and monkeys

Bleomycin, an antitumor antibiotic with specific activity against squamous cell tumors of the skin, was administered iv every 4 days for 11 or 31 treatments to 14 dogs (0.156–5 mg/kg/day) and 11 monkeys (0.5–8 mg/kg/day). Severe doserelated cutaneous toxicity included dermatitis, ulceration at pressure and friction sites, onychoptosis and focal alopecia. Foot pads of dogs housed in wire floor cages were more severely affected than those housed on solid floors. In dogs, lesions occurred only on footpads and the tail tip, while in monkeys the neck, elbows, cubital fossa, ischial callosities and palmar and plantar surfaces of the hands and feet were affected. Microscopic changes at pressure and friction sites included ulceration, focal necrosis, subacute inflammation, hemorrhage, edema and occasional foreign body granulomas. Collagen bundles at both pressure and non-pressure sites showed increased homogeneity, but elastic and reticular fibers showed no evident abnormalities. Atrophy of sweat glands and pilosebaceous apparatus was also observed. Previously reported depression of serum zinc concentrations correlated with the onset of skin lesions, and suggested that zinc deficiency played a role in the pathogenesis of the lesions. Integumentary lesions at pressure and friction sites were a good visual index of bleomycin toxicity.

The stoichiometric fate of azaserine metabolized in vitro by tissues from azaserine-treated dogs and mice☆

Abstract The in vitro metabolism of azaserine was determined in various tissues of mouse, dog, and rat with the aim of elucidating the stoichiometric relationship of azaserine transformation with the production of pyruvate, ammonia and glycolic acid. The influence of in vivo treatment with azaserine and ethyldiazoacetate on the in bitro metabolism of azaserine was also monitored in order to uncover any correlation between azaserine metabolism and histopathology. The stoichiometry of azaserine disappearance and pyruvate and ammonia formation was confirmed for mouse liver and demonstrated for dog tissues. Identification and stoichiometric production of glycolic acid as the 2-carbon moiety associated with the diazo group was established. The most active tissues in the dog were salivary and prostrate tissues which undergo morphological alteration after in vivo treatment with azaserine. In both azaserine and ethyldiazoacetate-treated dogs and mice the activity of the azaserine degrading enzyme was inhibited. Ethyldiazoacetate was less toxic and did not cause microscopic changes, and salivary lesions were absent in the mice treated with either drug.

Phenester (NSC-116 785): Convulsant effects in the dog of an alkylating agent with antitumor activity☆☆☆★

Abstract Phenester [acetic acid, (p-(bis (2 chlorethyl)-amino)-phenyl) ethyl ester] is known to produce marked oncolytic activity against the mammary adenocarcinoma 13,762 in rats. For evaluation of toxicity, 17 dogs were treated with single doses of 120, 80, 20, or 5 mg/kg, with 5 consecutive daily doses of 80, 28, 14, 7, or 3.5 mg/kg, or with 11 treatments of 7 mg/kg, at 4-day intervals. The essential toxicity consisted of centrally induced salivation, vomiting, muscle twitches, tremors, and finally clonic and tonic convulsions. EEG recordings (2 dogs) from the thalamus and cerebral cortex demonstrated subcortical and cortical spikes and 3–4 cps hypersynchronous slow waves which during tonic convulsions, progressed into cortical and subcortical seizures followed by postictal silence. Six of the 8 dogs that developed tonic convulsions died or became moribund during the seizures or a few days thereafter. Mortality resulted from treatment with up to 5 daily doses of 28 mg/kg ( 2 2 ), 14 mg/kg ( 1 2 ), or 7 mg/kg ( 2 5 ). The other dogs survived. Tonic convulsions were also noted in one of 2 dogs receiving 11 treatments at 4-day intervals with 7 mg/kg/day, and in 1 dog treated with a single dose of 80 mg/kg. Dogs treated with 5 daily doses of 3.5 mg/kg or with a single dose of 20 mg/kg did not manifest convulsions. The 6 dogs which became critically ill exhibited very severe or severe hypocellularity of the bone marrow ( 5 6 dogs), severe hypocellularity of the lymphoid tissues ( 6 6 dogs), severe bronchopneumonia ( 2 6 dogs) or intestinal toxicity ( 1 6 dogs). Hepatic and renal toxicity were negligible. In contrast to other alkylating agents, phenester failed to produce degenerative changes of the spermatogenic cells or important intestinal histopathologic changes; convulsive properties predominated. Treatment with 3.5 mg/kg/day for 5 consecutive days elicited vomiting, but was otherwise tolerated without adverse side effects (maximum tolerated dose).