Medeor gets FDA OK to trial therapy that aims to do away with transplant drugs

Patients who undergo organ transplants may no longer have to rely on lifelong immune-suppressing drugs, if Medeor Therapeutics has its way.

The California biotech says it has just been given the green light from the FDA to start trials of a personalized cell-based immunotherapy called MDR-101 that is designed to switch off the immune response to donated and transplanted organs.

More than 30,000 Americans get an organ transplant every year, and while success rates for these procedures are improving, it is estimated that up to a third of the most common transplants—such as heart, kidney, and liver—fail within 5 years.

Immunosuppressive drugs like cyclosporine and tacrolimus can help prevent that happening, but have to be taken for life and can cause side effects, as well as increasing the risk of infection, cancer, diabetes and heart disease. They can even damage the kidneys themselves, which is particularly bad news for kidney transplant recipients.

The FDA has cleared Medeor's Investigational New Drug (IND) application for MDR-101, and also agreed to a Special Protocol Assessment (SPA) that will allow the company to push ahead straight away with a phase 3 trial in living donor kidney transplants, due to start in the second half of this year. The SPA means the biotech can proceed without fear that the agency will take issue with its design, endpoints and statistical analyses later.

MDR-101 grew out of pioneering research conducted at Stanford University in the lab of Dr. Samuel Strober, M.D., which involved injecting blood stem cells and T cells from the donor at the time of transplant to try to convince the immune system of the recipient to accept the donated organ as if it was their own.

The procedure involves harvesting blood stem cells from the donor before the transplant. After the organ is transferred, the recipient is started on anti-rejection drugs and receives radiotherapy to further suppress the immune system. A few weeks later, the donor stem cells are infused into the transplant patient so they grow in the bone marrow and other immune tissues and become part of the recipient's immune system.

The technique has already been tested in a phase 1 trial involving HLA-matched donor organ transplants—for example, from siblings—but the hope is that eventually it could allow donor organs to be used where there is only a partial match. That could expand the pool of possible donors to include more distant family members, for example.

Last December Dr. Strober, the scientific founder of Medeor and a company board member, was awarded a $6.6 million grant from the California Institute for Regenerative Medicine to help fund the further development of the technology.

Medeor's chief medical officer, Scott Batty, M.D., said current treatment to prevent rejection of organ transplants "is far from optimal due to unacceptably high long-term failure rates and treatment-associated complications, and new approaches are greatly needed to relieve organ transplant recipients from the litany of undesirable effects associated with anti-rejection drug regimens."

"MDR-101 has the potential to address the two most critical transplant patient needs: preventing organ rejection and mitigating anti-rejection treatment-associated toxicities," he continued.