Cure for Type 1 Diabetes With Gene Therapy Demonstrated

First Posted: Feb 14, 2013 03:46 PM EST

With a single session of gene therapy, researchers at the Universitat Autònoma de Barcelona (UAB) have completely cured type 1 diabetes in dogs, involving the introduction of a “glucose sensor” into a muscle. Gene therapies seems to be on track to be the cure that didn't exist before for complex diseases, show-cased also by the therapy based on the first ever cure of HIV in the famous 'Berlin patient'.

It is the first time diabetes has been cured in large animals which represents a fundamental step towards applying the therapy in humans. The dogs recovered their health and no longer show symptoms of the disease. In some cases, monitoring continued for over four years, with no recurrence of symptoms.

The therapy is minimally invasive and thus simple. It consists of a single session of various injections in the animal’s rear legs using simple needles that are commonly used in cosmetic treatments.

These injections introduce gene therapy vectors, with a dual objective: to express the insulin gene and glucokinase genes. Glucokinase is the enzyme that regulates the uptake of glucose from the blood.

The trick is that when both genes act simultaneously, they function as a “glucose sensor,” which automatically regulates the uptake of glucose from the blood, thus reducing diabetic hyperglycemia, which is the excess of blood sugar associated with diabetes.

The study provides ample data showing the safety of gene therapy mediated by a new generation of very safe vectors known as 'adeno-associated vectors' (AAV). These vectors, derived from non-pathogenic viruses, are widely used in gene therapy and have been successful in treating several diseases. They are for example used in the first gene therapy medicine for humans ever approved by the European Medicines Agency, named Glybera®, that uses AAVs to treat a metabolic disease with similarities to diabetes.

Dogs treated with a single administration of gene therapy showed good glucose control at all times, both when fasting and when fed, improving on that of dogs given daily insulin injections, and with no episodes of hypoglycemia, even after exercise. Furthermore, the dogs treated with adeno-associated vectors improved their body weight and had not developed secondary complications four years after the treatment.

There have been multiple clinical trials in which AAV vectors have been introduced into skeletal muscle, so the strategy reported in this study is feasible for clinical translation, the researchers say.

The study was led by the head of the UAB’s Centre for Animal Biotechnology and Gene Therapy (CBATEG) Fàtima Bosch, and involved several other departments, institutes and hospitals both in Spain and the US.

Diabetes mellitus is the most common metabolic disease, and a large number of patients need complicated insulin treatment to survive. In spite of the use of insulin injections to control the disease, these patients often develop serious secondary complications like blindness, kidney damage or amputation of limbs. Moreover, in order to achieve good blood glucose control, insulin has to be injected two or three times a day, which brings a risk of hypoglycemia episodes (lowering of blood sugar): an additional problem that comes on top of the other hardships of the treatment.

David Callejas et al., Treatment of Diabetes and Long-term Survival Following Insulin and Glucokinase Gene Therapy, Diabetes, 2013, DOI: 10.2337/db12-1113

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