Management of adverse side-effects after chemotherapy in macaques as exemplified by streptozotocin: case studies and recommendations.

The chemotherapeutic streptozotocin is used for induction of diabetes in animal models including non-human primates. Being a cytotoxic nitrosourea compound, it can be associated with adverse events (AEs), mainly nausea and emesis, nephrotoxicity, elevated liver transaminase levels, pulmonary oedema and, most prominently, metabolic acidosis: these can be severe in some cases. The incidence and gravity are to some extent related to the characteristics of the individual animal, diagnostic tools, prompt recognition of symptoms and supportive measures. Careful animal selection, dose adaptation and supportive actions such as renal protective hydration are the main tools in managing AEs, but do not fully eliminate unavoidable and sometimes life-threatening conditions. In our centre we have built experience in a cohort of 78 cynomolgus and rhesus macaques in which six cases manifested severe AEs (8%). This experience has prompted implementation of strategies for early detection and management of adverse effects, together with an animal refinement programme. We present here specific pretreatment regimens, post-infusion laboratory evaluations, and flow charts to assess/treat metabolic acidosis and precipitating factors. Case reports of the six animals with severe AEs are presented to illustrate management of AEs, especially metabolic acidosis, and criteria for early euthanasia where appropriate. We conclude that improved monitoring and validated tools allow for optimal management of adverse effects in an early stage of their manifestation. Reduced morbidity and mortality not only improve individual animal wellbeing but also avoid model-induced confounding that diminishes the translational value of the experimental protocol.

Successful implementation of cooperative handling eliminates the need for restraint in a complex non-human primate disease model.

BACKGROUND: Streptozotocin-induced diabetic non-human primates are used to study efficacy and safety of innovative immunosuppression after islet transplantation. We implemented a training program for medical management of a chronic disease state. METHODS: Cooperation with hand feeding and drinking, shifting, and limb presentation were trained utilizing predominately positive but also negative reinforcement in 52 animals compared with 28 macaques subjected to conventional physical and/or chemical restraint. The success and timing of behavior acquisition was evaluated in a representative subset of 14 animals. RESULTS: Over 90% of animals were successful in behavior acquisition. Programmatically this resulted in complete elimination of chair restraint and negligible requirement for sedation. About half of the trained animals had no-to-moderate thymic involution, indicative of a substantial reduction in stress. CONCLUSION: Cooperative handling enhances animal well-being. This contributes to validity of scientific results and eliminates model-induced confounding that can obstruct interpretation of safety and efficacy data.

Refining the high-dose streptozotocin-induced diabetic non-human primate model: an evaluation of risk factors and outcomes.

In preparation for islet transplantation, diabetes was induced using streptozotocin (STZ) in non-human primates ranging from juveniles to adults with diverse body types: we studied the process with respect to the diabetic state and emergence of adverse events (AEs) and their severity, and identified risk factors for clinical and laboratory AEs. Pharmaceutical-grade STZ was given based on body surface area (BSA) (1050-1250 mg/m(2), equivalent to 80-108 mg/kg) or on body weight (BW) (100 mg/kg) to 54 cynomolgus and 24 rhesus macaques. AEs were related to risk factors, i.e. obesity parameters, BW and BSA, age and STZ dose in mg/m(2). Clinical AEs during the first days after infusion prompted euthanasia of three animals. Except for those three animals, diabetes was successfully induced as shown by circulating C-peptide levels, the intravenous glucose tolerance test and/or arginine stimulation test. C-peptide after infusion weakly correlated (P = 0.048) with STZ dose in mg/m(2). Grade ≥3 nephrotoxicity or hepatotoxicity (serum markers >3× baseline or >5 × baseline, respectively) occurred in about 10% of cases and were generally mild and reversible. Grade ≥2 clinical AEs occurred in seven of 78 animals, reversed in four cases and significantly correlated with obesity parameters. Taking girth-to-height ratio (GHtR) as an indicator of obesity, with threshold value 0.92-0.95, the positive predictive value of obesity for AEs was 92% and the specificity 94%. We conclude that diabetes is successfully induced in non-obese animals using a 100 mg/kg pharmaceutical grade STZ dose. Obesity is a significant risk factor, and animals with a higher than normal GHtR should preferably receive a lower dose. The incidence of relevant clinical or laboratory AEs is low. Careful monitoring and supportive medical intervention can result in recovery of AEs.

The streptozotocin-induced diabetic nude mouse model: differences between animals from different sources.

Diabetes is induced in mice by using streptozotocin (STZ), a compound that has a preferential toxicity toward pancreatic ß cells. We evaluated nude male mice from various sources for their sensitivity to a single high dose (160 to 240 mg/kg) of STZ. Diabetes was induced in male mice (age: median, 12 wk; interquartile range, 11 to 14 wk; body weight, about 30 g) from Taconic Farms (TAC), Jackson Laboratories (JAX), and Charles River Laboratories (CRL). Mice were monitored for 30 d for adverse side effects, blood glucose, and insulin requirements. In CRL mice given 240 mg/kg STZ, more than 95% developed diabetes within 4 to 5 d, and loss of body weight was relatively low (mean, 0.4 g). In comparison, both TAC and JAX mice were more sensitive to STZ, as evidenced by faster development of diabetes (even at a lower STZ dose), greater need for insulin after STZ, greater body weight loss (mean: TAC, 3.5 g; JAX, 3.7 g), and greater mortality. We recommend conducting exploratory safety assessments when selecting a nude mouse source, with the aim of limiting morbidity and mortality to less than 10%.