Progress towards the Replacement of the Rabbit Blood Sugar Test for the Quantitative Determination of the Biological Activity of Insulins (USP <121>) with an In Vitro Assay

For the quantification of insulin activity, United States Pharmacopeia (USP) general chapter <121> continues to require the rabbit blood sugar test. For new insulin or insulin analogue compounds, those quantitative data are expected for stability or comparability studies. At Sanofi, many rabbits were used to fulfil the authority's requirements to obtain quantitative insulin bioactivity data until the in vivo test was replaced. In order to demonstrate comparability between the in vivo and in vitro test systems, this study was designed to demonstrate equivalency. The measurement of insulin lispro and insulin glargine drug substance and drug product batches, including stress samples (diluted or after temperature stress of 30 min at 80 °C), revealed a clear correlation between the in vitro and in vivo test results. The recovery of quantitative in vitro in-cell Western (ICW) results compared to the in vivo test results was within the predefined acceptance limits of 80% to 125%. Thus, the in vitro ICW cell-based bioassay leads to results that are equivalent to the rabbit blood sugar test per USP <121>, and it is highly suitable for insulin activity quantification. For future development compounds, the in vitro in-cell Western cell-based assay can replace the rabbit blood sugar test required by USP <121>.

The Non-Human Primate in Safety Assessment of a Bifunctional Long-Acting Insulin Analogue

Species selection plays a pivotal part during non-clinical safety assessment in drug development. If possible, use of non-human primates (NHPs) should be avoided due to ethical considerations. However, limiting factors as lack of pharmacologic activity in other species could necessitate use of NHPs. LAI-PCSK9i is a bi-functional molecule combining a long-acting insulin analogue with a PCSK9 inhibitor peptide aiming to provide glycaemic control and to reduce plasma LDL concentrations. The NHP was chosen for the safety assessment of LAI-PCSK9i being the most relevant species with basal levels and plasma lipid composition closest to humans, while the dog and initially also the minipig were deemed irrelevant due to lack of pharmacologic activity on LDL-lowering and biological differences in lipid profiles. An in vivo tolerability and toxicokinetic study of LAI-PCSK9i in NHPs showed recurrent and severe hypoglycaemia at very low doses. Therefore, the minipig was re-evaluated and a follow-up study thoroughly assessing blood glucose and cholesterol levels and clinical signs illustrated that minipigs dosed with LAI-PCSK9i, tolerated the compound and LAI-PCSK9i decreased glucose and LDL over time. This work underlines that careful consideration is required when selecting species during safety assessment in drug development. The tolerability issue in NHPs led to the subsequent selection of the minipig for safety evaluation of LAI-PCSK9i although as a suboptimal alternative, which unexpectedly had a measurable pharmacologic response on LDL lowering. In conclusion, the NHPs may be unsuitable as test species for safety assessment of long-acting insulin analogues due to high sensitivity to recurring hypoglycaemic episodes.

Determination of insulin-related lipohypertrophy frequency and risk factors in patients with diabetes

INTRODUCTION

Insulin, which is used in the treatment of diabetes mellitus (DM), may lead to the development of lipohypertrophy (LH) which can negatively affect the management of diabetes mellitus. Two common methods to detect LH are palpation and superficial subcutaneous ultrasonography (SSU). We investigated the frequency of non-palpable LH using SSU, as well as examining risk factors.

METHOD

We included in our study patients who had been receiving insulin injections at least twice a day for over one year without palpable LH. The epidermis and the subcutaneous tissue thickness of each region were examined using SSU. The presence of LH and associated risk factors for LH were evaluated.

RESULTS

We included 136 patients in our study. The mean age of all patients was 52.87±14.93 years, 59.6% were female and 73.5% had type 2 DM. The duration of DM and insulin usage were 15.76±9.20 and 11.42±8.26 years, respectively. The mean body mass index (BMI) of all patients was 30.59±7.40kg/m². Non-palpable LH was detected in 87.5% (n=116) of the patients using SSU. In the multivariate logistic regression analyses, total cholesterol level, short-acting insulin dose and coronary artery disease (CAD) were associated with LH presence.

CONCLUSION

Non-palpable LH can be seen at high rates in patients who have multiple insulin injections. Palpation is likely not enough to detect LH and we believe it would be appropriate to evaluate the presence of LH using SSU, especially for those who need high-dose insulin to control hyperglycaemia.

Determination of insulin-related lipohypertrophy frequency and risk factors in patients with diabetes

INTRODUCTION

Insulin, which is used in the treatment of diabetes mellitus (DM), may lead to the development of lipohypertrophy (LH) which can negatively affect the management of diabetes mellitus. Two common methods to detect LH are palpation and superficial subcutaneous ultrasonography (SSU). We investigated the frequency of non-palpable LH using SSU, as well as examining risk factors.

METHOD

We included in our study patients who had been receiving insulin injections at least twice a day for over one year without palpable LH. The epidermis and the subcutaneous tissue thickness of each region were examined using SSU. The presence of LH and associated risk factors for LH were evaluated.

RESULTS

We included 136 patients in our study. The mean age of all patients was 52.87±14.93 years, 59.6% were female and 73.5% had type 2 DM. The duration of DM and insulin usage were 15.76±9.20 and 11.42±8.26 years, respectively. The mean body mass index (BMI) of all patients was 30.59±7.40kg/m2. Non-palpable LH was detected in 87.5% (n=116) of the patients using SSU. In the multivariate logistic regression analyses, total cholesterol level, short-acting insulin dose and coronary artery disease (CAD) were associated with LH presence.

CONCLUSION

Non-palpable LH can be seen at high rates in patients who have multiple insulin injections. Palpation is likely not enough to detect LH and we believe it would be appropriate to evaluate the presence of LH using SSU, especially for those who need high-dose insulin to control hyperglycaemia.

Advances in selecting appropriate non-rodent species for regulatory toxicology research: Policy, ethical, and experimental considerations

In vivo animal studies are required by regulatory agencies to investigate drug safety before clinical trials. In this review, we summarize the process of selecting a relevant non-rodent species for preclinical studies. The dog is the primary, default non-rodent used in toxicology studies with multiple scientific advantages, including adequate background data and availability. Rabbit has many regulatory advantages as the first non-rodent for the evaluation of reproductive and developmental as well as local toxicity. Recently, minipigs have increasingly replaced dogs and rabbits in toxicology studies due to ethical and scientific advantages including similarity to humans and breeding habits. When these species are not relevant, nonhuman primates (NHPs) can be used as the available animal models, especially in toxicology studies investigating biotherapeutics. Particularly, based on the phylogenetic relationships, the use of New-World marmosets can be considered before Old-World monkeys, especially cynomolgus with robust historical data. Importantly, the use of NHPs should be justified in terms of scientific benefits considering target affinity, expression pattern, and pharmacological cross-reactivity. Strict standards are required for the use of animals. Therefore, this review is helpful for the selection of appropriate non-rodent in regulatory toxicology studies by providing sufficient regulatory, ethical, and scientific data for each species.

Scientific and Regulatory Policy Committee Points to Consider: Histopathologic Evaluation in Safety Assessment Studies for PEGylated Pharmaceutical Products

Colorless, intracytoplasmic vacuoles occur in multiple tissues in animals following repeated administration of polyethylene glycol (PEG)-conjugated molecules. The extent of vacuolation depends on physical characteristics and molecular backbone of the PEG and the dose, product, drug target/pharmacology, and duration of exposure. The collective experience gathered from multiple nonclinical toxicology studies of PEGylated biopharmaceuticals indicates that in general, PEG-related vacuolation is not associated with demonstrable cell and tissue damage or dysfunction and is reversible with sufficient duration of drug-free periods. Existing data are insufficient to predict whether nonclinical animal species differ in their sensitivity to develop PEG-associated vacuoles; however, recent data suggest that there may be species differences. Recent comprehensive reviews have addressed the basic challenges in developing PEGylated pharmaceutical products, including general reference to and description of PEG-associated tissue findings. These manuscripts have identified gaps in our current understanding of PEG-associated vacuolation, including the lack of a widely accepted standardized histological terminology and criteria to record and grade the severity of vacuolation as well as insufficient knowledge regarding the nature of the contents of these vacuoles. The goal of this article is to help address some of the gaps identified above by providing points to consider, including a pictorial review of PEG-associated microscopic findings, when evaluating and reporting the extent, severity, and significance (adversity or lack of adversity) of PEG-associated cytoplasmic vacuolation in safety assessment studies.

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