Subcutaneous Alfaxalone-XylazineBuprenorphine for Surgical Anesthesia and Echocardiographic Evaluation of Mice (Mus musculus).

Alfaxalone is a commonly used injectable anesthetic in dogs and cats due to its minimal cardiovascular side effects. Data for its use in mice are limited and demonstrate strain- and sex-associated differences in dose-response relationships. We performed a dose-comparison study of alfaxalone-xylazine-buprenorphine (AXB) in Crl: CFW (SW) mice. Subcutaneous injection of 50 mg/kg alfaxalone-10 mg/kg xylazine-0.1 mg/kg buprenorphine HCl consistently achieved a surgical plane of anesthesia (loss of toe pinch) for 48.6 ± 4.7 and 60.8 ± 9.6 min in females and males, respectively. The same dose and route of AXB induced a surgical plane of anesthesia in C57Bl/6NCrl (females: 42.3 ± 11.2 min; males: 51.6 ± 12.3 min), NCr-Foxn1nu (females: 76.8 ± 32.5 min; males: 80.0 ± 1.2 min), and NOD. Cg-Prkdc SCID Il2rg tm1Wjl /SzJCr (females: 56.0 ± 37.2 min and males: 61.2 ± 10.2 min) mice. We found no significant difference in the duration of the surgical plane of anesthesia between males and females within the mouse strains Crl: CFW (SW), C57Bl/6NCrl, NCr-Foxn1nu, and NOD. Cg-PrkdcSCID Il2rgtm1Wjl /SzJCr. We next performed an echocardiography study (n = 5 per group) of Crl: CFW (SW) mice ( n = 5 per group) to compare subcutaneous AXB anesthesia with that produced by intraperitoneal injection of 100 mg/kg ketamine and 10 mg/kg xylazine (KX). AXB induced significantly less bradycardia (295.4 ± 29 bpm) than KX (185.8 ± 38.9 bpm) did, with no significant differences in cardiac output, ejection fraction, end-diastolic volume, end-systolic volume, or fractional shortening. These results suggest that subcutaneous administration of AXB is a viable alternative to KX for inducing a surgical plane of anesthesia in Crl: CFW (SW), C57Bl/6NCrl, NCr-Foxn1nu, and NOD. Cg-PrkdcSCID Il2rgtm1Wjl /SzJCr mice, regardless of sex. AXB may also be a better injectable anesthetic option as compared with KX for avoiding adverse cardiac effects in mice.

Preclinical Therapeutic Efficacy of RAF/MEK/ERK and IGF1R/AKT/mTOR Inhibition in Neuroblastoma.

Activating mutations in the RAS/MAPK pathway are observed in relapsed neuroblastoma. Preclinical studies indicate that these tumors have an increased sensitivity to inhibitors of the RAS/MAPK pathway, such as MEK inhibitors. MEK inhibitors do not induce durable responses as single agents, indicating a need to identify synergistic combinations of targeted agents to provide therapeutic benefit. We previously showed preclinical therapeutic synergy between a MEK inhibitor, trametinib, and a monoclonal antibody specific for IGF1R, ganitumab in RAS-mutated rhabdomyosarcoma. Neuroblastoma cells, like rhabdomyosarcoma cells, are sensitive to the inhibition of the RAS/MAPK and IGF1R/AKT/mTOR pathways. We hypothesized that the combination of trametinib and ganitumab would be effective in RAS-mutated neuroblastoma. In this study, trametinib and ganitumab synergistically suppressed neuroblastoma cell proliferation and induced apoptosis in cell culture. We also observed a delay in tumor initiation and prolongation of survival in heterotopic and orthotopic xenograft models treated with trametinib and ganitumab. However, the growth of both primary and metastatic tumors was observed in animals receiving the combination of trametinib and ganitumab. Therefore, more preclinical work is necessary before testing this combination in patients with relapsed or refractory RAS-mutated neuroblastoma.