Drug could double life of donor organs
Doctors are to begin the trial of a treatment that could double the time transplanted organs survive in the body.
The 20-minute procedure coats donor organs in a protective shield that stops them being rejected by the patient’s immune system. The treatment is expected to prolong the time that organs remain healthy in patients’ bodies and increase their shelf life so they can be stored for longer or transported further before being used.
If the treatment works, it could ease the burden on organ-transplant services, where there is a growing gap between the supply of, and demand for, donor organs. Last year in the United Kingdom, 8 000 people were on the waiting list for kidney transplants, but only 2 500 operations took place. In the past year, 448 patients died while waiting for an organ.
People who receive transplants must take drugs to suppress their immune systems, but the body still reacts enough to cause transplants to fail. A transplanted kidney lasts on average only 10 years, about one-third of the time it could last. Organs such as hearts and livers fail even sooner.
The consequence is that patients who have had one donor organ often need another. The new treatment, developed by researchers at King’s College London, is based on the defence mechanism healthy organs use to shield themselves from the immune system.
Protein molecules that dot the surface of organs keep the immune system in check and prevent it from launching an attack. But these proteins are lost when organs are removed from the body, handled and stored on ice.
The King’s College team found a way to manufacture these proteins in the laboratory and produced a drug called mirococept, which can be fed into the organ with a drip. ‘We have engineered a protein, mirococept, to combat organ damage during transit outside the human body and immediately after transplantation,” said Dr Richard Smith, the director of the Protein Therapeutics Laboratory.
“It is an artificial replacement for complement regulators. If enough mirococept proteins reach the organ’s cell membranes, it can prevent the complement cascade from starting and increases the number of donor organs suitable for transplantation.” Studies suggest the procedure could extend the life of an implanted kidney by about seven years.
“If the treatment goes to plan, it can be expected to almost double the life of a graft,” said Steven Sacks, the director of the UK’s Medical Research Council’s Centre for Transplantation. Scientists believe the treatment will also extend the shelf life of donor organs. This could reduce wastage and double the number of organs that work properly once they are transplanted, doctors say.
In early tests, only a fifth of organs worked properly after being stored on ice for 16 hours, compared with 50% of those treated with mirococept. A recent pilot study of the treatment on 16 patients found it was safe to use. The group now plans to recruit more than 300 patients for a trial to take place at transplant centres across the country.
The trial is expected to begin next year and will investigate how much of the drug is needed to treat organs for them to be protected. If it is successful, doctors will need to do a final, much larger trial to study how much longer treated donor organs survive in patients.
Sacks said the treatment could be available in hospitals in five years. Patients who receive donated organs treated with mirococept will still need to take drugs to suppress their immune systems, but doctors said an aim of their research was to see if the use of such drugs, which can increase a patient’s risk of cancer, could be reduced.