Update on the Management of Diabetic Retinopathy: Anti-VEGF Agents for the Prevention of Complications and Progression of Nonproliferative and Proliferative Retinopathy

Diabetic retinopathy (DR) is a microvascular disease caused by poorly controlled blood glucose, and it is a leading cause of vision loss in people with diabetes. In this review we discuss the current management of DR with particular focus on the use of intraocular anti-vascular endothelial growth factor (anti-VEGF) agents. Intraocular anti-VEGF agents were first studied in the 1990s, and now several of these agents are either FDA approved or used off-label as first-line treatments for DR. Recent evidence shows that anti-VEGF agents can halt the progression of markers of DR severity, reduce the risk of DR worsening, and reduce the onset of new macular edema. These significant benefits have been demonstrated in patients with proliferative DR and the milder nonproliferative DR (NPDR). A wealth of evidence from recent trials and meta-analyses has detailed the intraoperative and postoperative benefits of adjunctive anti-VEGF therapy prior to pars plana vitrectomy (PPV) for proliferative DR with vitreous hemorrhage. In this review, we also discuss literature comparing various anti-VEGF injection regimens including monthly, quarterly, as-needed, and treat and extend protocols. Combination protocols with panretinal photocoagulation (PRP) or PPV are also discussed. Current evidence suggests that anti-VEGF therapies are effective therapy for NPDR and PDR and may also provide significant benefits when used adjunctively with other DR treatment modalities such as PRP or PPV.

Hypertensive cerebral hemorrhage with undetectable plasma vascular endothelial growth factor levels in a patient receiving intravitreal injection of aflibercept for bilateral diabetic macular edema: a case report

Background

Intravitreal injections of anti-vascular endothelial growth factor are commonly used to treat macular diseases, including diabetic macular edema. Anti-vascular endothelial growth factor drugs can enter the systemic circulation after intravitreal injections and appear to suppress circulating vascular endothelial growth factor levels. However, whether this can cause any systemic adverse events remains unknown.

Case presentation

A 70-year-old Japanese man diagnosed with diabetic macular edema in both eyes was treated with anti-vascular endothelial growth factor intravitreal injections. One month after receiving two intravitreal injections of aflibercept 1 week apart for diabetic macular edema in both eyes, he complained of a severe acute headache. The patient was diagnosed with hypertensive cerebral hemorrhage of the occipital lobe based on an elevated blood pressure of 195/108 mmHg and the results of computed tomography and magnetic resonance imaging of his brain. The patient was treated with an intravenous injection of nicardipine hydrochloride to lower his systemic blood pressure. Two days after the stroke, the patient began oral treatment with 80 mg/day telmisartan, which was continued for 3 days, and the telmisartan dose was reduced to 40 mg/day thereafter. His blood pressure promptly dropped to 130/80 mmHg, and his severe headache disappeared. One year after the cerebrovascular stroke, the telmisartan was discontinued because his blood pressure stabilized at a normal level. His plasma vascular endothelial growth factor levels were measured via specific enzyme-linked immunosorbent assay before and after the intravitreal injections of aflibercept. Immediately before the injections, the vascular endothelial growth factor level was 28 pg/ml, but it rapidly fell below the detection limit within 1 week, where it remained for over 2 months. Two days before the cerebral hemorrhage, his plasma vascular endothelial growth factor level was below the detection limit, and 2 months later after the stroke, his plasma vascular endothelial growth factor level recovered to 41 pg/ml.

Conclusion

This case suggests that hypertension and resultant cerebral hemorrhage can occur in patients with diabetic macular edema when plasma vascular endothelial growth factor levels are systemically decreased below the detection limit for a prolonged time after local injections of anti-vascular endothelial growth factor agents into the vitreous cavity. Therefore, severely reduced plasma vascular endothelial growth factor levels could be a higher risk factor to develop generally infrequent stroke. Ophthalmologists should be aware of possible severe reduction of plasma vascular endothelial growth factor levels and resultant increase in blood pressure after intravitreal injections of an anti-vascular endothelial growth factor drug. If the plasma vascular endothelial growth factor levels could be monitored more easily and quickly during the treatment, it would help to prevent adverse events.

Clinical Efficacy and Safety of Angiogenesis Inhibitors: Sex Differences and Current Challenges

Vasoactive molecules, such as vascular endothelial growth factor (VEGF) and endothelins, share cytokine-like activities and regulate endothelial cell (EC) growth, migration and inflammation. Some endothelial mediators and their receptors are targets for currently approved angiogenesis inhibitors, drugs that are either monoclonal antibodies raised towards VEGF, or inhibitors of vascular receptor protein kinases and signaling pathways. Pharmacological interference with the protective functions of ECs results in a similar spectrum of adverse effects. Clinically, the most common side effects of VEGF signaling pathway inhibition include an increase in arterial pressure, left ventricular (LV) dysfunction ultimately causing heart failure, and thromboembolic events, including pulmonary embolism, stroke, and myocardial infarction. Sex steroids such as androgens, progestins, and estrogen and their receptors (ERα, ERβ, GPER; PR-A, PR-B; AR) have been identified as important modifiers of angiogenesis, and sex differences have been reported for anti-angiogenic drugs. This review article discusses the current challenges clinicians are facing with regard to angiogenesis inhibitor treatments, including the need to consider sex differences affecting clinical efficacy and safety. We also propose areas for future research taking into account the role of sex hormone receptors and sex chromosomes. Development of new sex-specific drugs with improved target and cell-type selectivity likely will open the way personalized medicine in men and women requiring antiangiogenic therapy and result in reduced adverse effects and improved therapeutic efficacy.