Perspective: APOBEC mutagenesis in drug resistance and immune escape in HIV and cancer evolution

The apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) mutational signature has only recently been detected in a multitude of cancers through next-generation sequencing. In contrast, APOBEC has been a focus of virology research for over a decade. Many lessons learnt regarding APOBEC within virology are likely to be applicable to cancer. In this review, we explore the parallels between the role of APOBEC enzymes in HIV and cancer evolution. We discuss data supporting the role of APOBEC mutagenesis in creating HIV genome heterogeneity, drug resistance, and immune escape variants. We hypothesize similar functions of APOBEC will also hold true in cancer.

The bioequivalence of a single intravenous administration of the anesthetic alfaxalone in cyclodextrin versus alfaxalone in cyclodextrin plus preservatives in cats

To demonstrate the bioequivalence of alfaxalone in cyclodextrin (Reference Product) to a formulation of alfaxalone in cyclodextrin also containing the preservatives ethanol, chlorocresol, and benzethonium chloride (Test Product) when administered for the purpose of inducing anesthesia in the cat. Blinded, single-dose, randomized, two-period, two-sequence, cross-over bioequivalence study with a 7-day washout period between treatments. Twenty-four (12 neutered males and 12 intact females), healthy, adult cats weighing 4.1±0.9 kg. Cats were administered 5 mg/kg IV of alfaxalone in the Reference or Test Product using a randomized cross-over design. One-milliliter venous blood samples were collected at predetermined time points to 12 hr after drug administration to determine alfaxalone plasma concentration over time. Alfaxalone concentrations were determined by a validated analytical testing method using HPLC-MS/MS. Plasma profiles of alfaxalone concentration against time were analyzed by noncompartmental analysis. The pivotal variables for bioequivalence were AUC_last and C_max . Equivalence was achieved if the 90% confidence interval for AUC_last and C_max fell into the asymmetric ±20% interval (0.80-1.25). Physiological variables, quality of anesthesia visual analog scale (VAS) scoring and anesthetic event times were recorded. ANOVA or ANCOVA (single time point), RMANOVA or RMANCOVA (multiple time point) was used for normally distributed data. GLIMMIX was used for nonnormally distributed data. VAS scores were analyzed as for blood bioequivalence data. Variables were evaluated for safety and assessed at alpha = 0.10. C_max and AUC_last for Reference and Test Products were statistically bioequivalent. No physiological variables except for a drug by time interaction for respiratory rate differed between treatment groups, and this difference was not clinically relevant. No anesthetic event times or VAS scores for quality of anesthesia were different between treatment groups. Neither formulation caused pain upon injection. The Reference and Test Products are pharmaceutically bioequivalent formulations when administered as a single intravenous administration for the purpose of induction of anesthesia in cats.

Induction of heart failure: haemodynamic comparison of three different canine models

We compared three methods: arteriovenous anastomosis, doxorubicin administration, and combination of anastomosis and doxorubicin, with the intention of designing a simple, stable model of chronic heart failure. Twelve dogs were divided into three groups of four. One group received carotid-jugular anastomosis (Ana series), another group received anastomosis and doxorubicin injection (A/D series), and the last group received only doxorubicin (Dox series). Animals were followed for eight weeks. Fifteen different haemodynamic parameters were tracked and compared to baseline values. After eight weeks, diastolic pressure in the right atrium increased from 3.8±2.0 mmHg at baseline to 5.3±5.9 mmHg in the Ana series, to 6.3±3.3 mmHg in the Dox series and to 8.0±2.0 mmHg in the A/D series ( P<0.05 A/D vs. baseline). Systolic pulmonary wedge pressure increased from 11.6±2.0 mmHg at baseline to 15.5±3.4 mmHg in the Ana series, 14.0±3.7 mmHg in the Dox series and 17.3±4.2 mmHg in the A/D series ( P = NS vs. baseline). Left ventricular ejection fraction decreased from 53.9±10% at baseline to 36.1±5.6% in the Ana series ( P<0.05 vs. baseline), 31.5±5.4% in the Dox series ( P<0.05 vs. baseline) and 25.8±5.8% in the A/D series ( P<0.001 vs. baseline, P<0.05 vs. Ana series and Dox series). In conclusion, eight weeks are not enough to produce stable heart failure using arteriovenous anastomosis alone. Doxorubicin administration alone produces a left ventricular failure. However, a combination of both of these interventions provides a more stable model of right-and left-sided heart failure