Carcinogenicity Evaluation of Baclofen in TgrasH2 Mice.

Baclofen is a γ-aminobutyric acid-B receptor agonist used for control of spastic muscle activity and as a treatment for alcohol abuse. The review of the nonclinical database suggested a data gap for potential carcinogenicity following long-term use. Regulatory requirements for pharmaceutical safety testing of cancer-causing potential have historically included 2-year rodent studies in rats and mice. The availability of transgenic models with greater specificity and sensitivity to carcinogens provides safety testing alternatives that align with the 3Rs. The carcinogenicity of baclofen was evaluated in CB6F1-TgrasH2 transgenic mice following daily oral administration at 45, 90, and 180 mg/kg/d for 26 weeks, preceded by a 2-week drug-conditioning period. There were no treatment-related palpable masses or neoplastic findings, and survival rates were not affected by the baclofen treatment. In conclusion, baclofen was considered as noncarcinogenic in CB6F1-TgrasH2 mice, which is consistent with results previously obtained in a 2-year rat study.

Nonclinical safety assessment of repeated administration and biodistribution of ChAd3-EBO-Z Ebola candidate vaccine.

ChAd3-EBO-Z is an investigational adenovirus-based vaccine for the prevention of Ebola virus disease. Two nonclinical studies were performed to evaluate the biodistribution, local tolerance and potential local and systemic toxic effects of this vaccine. In the biodistribution study, rats received a single intramuscular injection of either ChAd3-EBO-Z or saline. Enlargement of the draining lymph nodes, starting on day 2, was noticed in ChAd3-EBO-Z-treated rats, indicating that an immune response had taken place. Viral DNA was mainly found at the injection sites and in the draining lymph nodes, from where it progressively disappeared during the observation period, while it was found only transiently and occasionally in other organs. In the repeated-dose toxicity study, either ChAd3-EBO-Z or saline was administered intramuscularly to rabbits on two occasions with a 2-week interval. General health status, rectal temperature, local tolerance, ophthalmology, hematology, coagulation and blood chemistry parameters were monitored. Macroscopic and microscopic evaluations were performed. Treatment-related changes included a transient increase in neutrophil count, C-reactive protein and fibrinogen levels, and a transient decrease in platelet count. As expected, microscopic observations 3 days after the second injection were related to the elicited inflammatory reaction, and these inflammatory responses had almost completely disappeared 29 days after the second immunization. In conclusion, the vaccine was locally and systemically well-tolerated and the viral vector was partially or totally cleared from the organs where it disseminated, supporting the clinical development of the vaccine.

Carcinogenicity testing of eliglustat in mice and rats.

Eliglustat is a novel glucosylceramide synthase inhibitor for long-term oral treatment of type 1 Gaucher disease (GD1), an inherited metabolic disorder. The carcinogenic potential of this drug has been evaluated in lifetime carcinogenicity bioassays in mice and rats. Administration of eliglustat to Swiss CD-1 mice at 0, 10, 25 or 75 mg/kg/day for 104 weeks by dietary admixture did not influence survival or bodyweight evolution, or produce any clinical indication of poor condition. At histopathology, no increases in tumor incidence for any tumor type were attributed to treatment with eliglustat. Systemic exposure to eliglustat was confirmed by a reduction in circulating levels of glucosylceramide. Administration of eliglustat to Sprague-Dawley rats by oral gavage for 105 weeks at 0, 10, 25 or 75 mg/kg/day (males) or 103 weeks at 0, 5, 15 or 50 mg/kg/day (females) did not affect survival rates, but resulted in reduced bodyweight evolution in male rats (-18% at high dose), indicating that the MTD had been achieved. At histopathology, no increases in tumor incidence were attributed to treatment with eliglustat. Systemic exposure was confirmed by toxicokinetic analyses. In conclusion, eliglustat was not carcinogenic to mice or rats in standard lifetime bioassays.