Tyrosine kinase targeting: A potential therapeutic strategy for diabetes

Tyrosine kinase inhibitors (TKIs) have been studied extensively in cancer research, ultimately resulting in the approval of many drugs for cancer therapy. Recent evidence from reported clinical cases and experimental studies have suggested that some of these drugs have a potential role in diabetes treatment. These TKIs include imatinib, sunitinib, dasatinib, erlotinib, nilotinib, neratinib, and ibrutinib. As a result of promising findings, imatinib has been used in a phase II clinical trial. In this review, studies that used TKIs in the treatment of both types of diabetes are critically discussed. In addition, the different molecular mechanisms of action of these drugs in diabetes models are also highlighted to understand their antidiabetic mode of action.

Pazopanib-associated secondary adrenal insufficiency in a patient with malignant solitary fibrous tumor

INTRODUCTION

Pazopanib is an agent that is being successfully used in soft tissue sarcomas. Some endocrine side effects may develop during pazopanib treatment. Here, we presented a case diagnosed with secondary adrenal insufficiency while being investigated for etiology of hypoglycemia which developed after pazopanib.

CASE REPORT

A 69-year-old male patient was operated in June 2019 due to a lung mass 26 × 18 × 10 cm in size. Pathological diagnosis revealed a solitary fibrous tumor with malignant behavior. The patient received three lines of chemotherapy. After pazopanib treatment, a hypoglycemic attack was reported.Management and outcome: Blood cortisol and ACTH (Adrenocorticotropic hormone) levels were not increased at the time of the hypoglycemic attack, and levels of other pituitary hormones were found to be normal. Electrolyte levels were in normal range. Since the counteracting hormone did not reach a sufficient level, it was considered secondary adrenal insufficiency. Hypoglycemic attacks did not occur during follow-up while taking steroid therapy and pazopanib.

DISCUSSION

A single case of primary adrenal insufficiency has been reported in the literature. We here present a case who developed hypoglycemia after pazopanib and was diagnosed with drug-associated secondary adrenal insufficiency. When hypoglycemia develops during pazopanib treatment, we must be aware of adrenal insufficiency.

Should everolimus be stopped after radiological progression in metastatic insulinoma? A "cons" point of view

Insulinoma is a rare pancreatic neuroendocrine tumor (pNET) potentially associated with severe hypoglycaemic crisis. The great majority of these tumors are benign. In patients with metastatic malignant insulinoma, systemic therapies aim to control both the syndrome and tumor growth. Everolimus is a drug approved for the management of advanced pNETs that can achieve both these goals. According to international guidelines and regulatory authorities, everolimus in patients with pNET should be continued until the demonstration of disease progression with standard radiologic imaging techniques. The drug is neither recommended nor authorized beyond progression. This could not be the case of advanced insulinoma patients since the antineoplastic and the glycaemic effects of everolimus seem to follow independent mechanisms. The authors present here their point of view in favor of continuing everolimus beyond progression in symptomatic insulinoma patients on the basis of a robust rationale and describing a case.

Multitargeted kinase inhibitors imatinib, sorafenib and sunitinib perturb energy metabolism and cause cytotoxicity to cultured C2C12 skeletal muscle derived myotubes

Tyrosine kinase inhibitors (TKIs) have advanced cancer treatment and prognosis but have also resulted in adverse effects such as fatigue, diarrhea, hypothyroidism, and other toxicities. We investigated TKI effects on skeletal muscle as a possible explanation of TKI induced fatigue. Changes in mitochondrial function due to inhibition of oxidative phosphorylation complexes, generation of superoxides, and inhibition of key transporters involved in uptake of glucose and/or nucleosides may result in alteration of energy metabolism and/or mitochondrial function. We investigated effects of imatinib, sorafenib and sunitinib on these processes in cultured C2C12 murine skeletal muscle cells. Imatinib, sorafenib and sunitinib were cytotoxic to C2C12 cells with IC₅₀ values of 20, 8 and 8 µM, respectively. Imatinib stimulated glucose uptake and inhibited complex V activity by 35% at 50 µM. Sorafenib inhibited complex II/III and V with IC₅₀ values of 32 and 28 µM, respectively. Sorafenib caused activation of caspase 3/7 and depolarization of mitochondrial membranes occurred very rapidly with complete loss at 5-10 µM. Sunitinib inhibited Complex I with an IC₅₀ value of 38 µM and caused ATP depletion, caspase 3/7 activation, an increase in reactive oxygen species (ROS), and decreased nucleoside and glucose uptake. In conclusion, imatinib, sunitinib and sorafenib caused changes in mitochondrial complex activities, glucose and nucleoside uptake leading to decreased energy production and mitochondrial function in a skeletal muscle cell model, suggesting that these changes may play a role in fatigue, one of the most common adverse effects of TKIs.

A pharmacokinetic study on lapatinib in type 2 diabetic rats

BACKGROUND

Diabetes mellitus (DM) is a complex metabolic disorder which affects the function of numerous tissues and alters the pharmacokinetic parameters of many drugs. As many oncological patients are diabetics, it is important to determine the influence of this chronic disease on the pharmacokinetics (PK) of anticancer drugs. Lapatinib is a tyrosine kinase inhibitor (TKI), approved for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The aim of the study was to compare the PK of lapatinib in normal and type 2 diabetes mellitus (T2DM) model rats. Additionally, the effect of lapatinib on blood glucose concentrations was examined.

METHODS

The PK of lapatinib was studied in healthy rats (n=6, the healthy group) and T2DM model rats (n=6, the diabetic group). The rats received lapatinib orally as a single dose of 50mg. Plasma concentrations of lapatinib were measured with high-performance liquid chromatography method coupled with a tandem mass spectrometry.

RESULTS

The plasma concentrations of lapatinib were increased in the T2DM model rats. There were statistically significant differences between the groups in C_max (p=0.0104) and AUC_0-t (p=0.0265). The reduction of glycaemia in the range of 1.2-41.5% and in the range of 4.1-36.8% was observed in the diabetic and healthy animals, respectively.

CONCLUSIONS

Higher concentrations of lapatinib in the diabetic rats may suggest the need for application of lower doses of this TKI in patients with DM.

A PPARγ transcriptional cascade directs adipose progenitor cell-niche interaction and niche expansion

Adipose progenitor cells (APCs) reside in a vascular niche, located within the perivascular compartment of adipose tissue blood vessels. Yet, the signals and mechanisms that govern adipose vascular niche formation and APC niche interaction are unknown. Here we show that the assembly and maintenance of the adipose vascular niche is controlled by PPARγ acting within APCs. PPARγ triggers a molecular hierarchy that induces vascular sprouting, APC vessel niche affinity and APC vessel occupancy. Mechanistically, PPARγ transcriptionally activates PDGFRβ and VEGF. APC expression and activation of PDGFRβ promotes the recruitment and retention of APCs to the niche. Pharmacologically, targeting PDGFRβ disrupts APC niche contact thus blocking adipose tissue expansion. Moreover, enhanced APC expression of VEGF stimulates endothelial cell proliferation and expands the adipose niche. Consequently, APC niche communication and retention are boosted by VEGF thereby impairing adipogenesis. Our data indicate that APCs direct adipose tissue niche expansion via a PPARγ-initiated PDGFRβ and VEGF transcriptional axis.

Adipocyte progenitor cells (APCs) are found tethered to adipose tissue blood vessel walls and can differentiate into adipocytes. Here the authors show that PPARγ controls angiogenesis by stimulating APC–blood vessel interaction and retention via a transcriptional network that includes PDGFRβ and VEGF.

The early effect of sunitinib on insulin clearance in patients with metastatic renal cell carcinoma

AIMS

In patients with diabetes treated with sunitinib symptomatic hypoglycaemia has been reported. To explore the mechanism of this adverse effect we performed a prospective study to investigate the effect of sunitinib on insulin concentration, insulin clearance and insulin sensitivity.

METHODS

We studied the early effects of sunitinib on insulin sensitivity and insulin clearance with a hyperinsulinaemic euglycaemic clamp (insulin infusion rate 60 mU m−2 min−1; steady-state 90–120 min) in patients with renal cell carcinoma before and 1 week after the start of sunitinib 50 mg day−1. Insulin sensitivity index (SI) was defined as steady-state glucose disposal divided by the steady-state plasma insulin.

RESULTS

Ten patients (one with diabetes, treated with metformin) were included in the study protocol. Steady-state insulin concentrations during the clamp increased after 1 week of sunitinib (from 128.9 ± 9.0 mU l−1 to 170.8 ± 12.8 mU l−1, P < 0.05; 95% CI on difference − 64.3, −19.6). The calculated insulin sensitivity index decreased from 0.22 ± 0.04 before to 0.18 ± 0.02 μmol kg−1 min−1 per mU l−1 insulin (P < 0.05; 95% CI on difference 0.07, 0.08). As the insulin infusion rate was similar for both clamps, the increased steady-state insulin concentration indicates reduced insulin clearance.

CONCLUSION

Sunitinib affects insulin clearance which could possibly lead to overexposure to insulin in patients using insulin or insulin-secretion stimulating agents.