Lilly's arthritis drug found to prevent potentially lethal stem cell transplant complications

Researchers at St Louis Washington University School of Medicine have uncovered a promising extra application of a particular Janus Kinase (JAK) inhibitor, part of an experimental class of drugs currently undergoing trials for rheumatoid arthritis, finding that they were able to prevent a common, life-threatening side-effect of stem cell transplants.

The side-effect, known as graft-versus-host disease, occurs when transplanted stem cells attack the host’s organs and tissues, and affects around half of all patients receiving such transplants. The disease can remain for months or even years, even killing some patients before their cancer does.

"Transplanted donor stem cells -- and more specifically, the T cells in the donor stem cell product -- are particularly good at fighting off leukemia, but these cells can go haywire, unfortunately, and attack the patient's healthy tissues, causing graft-versus-host disease," explained Senior Author Dr John F DiPersio, the Virginia E and Sam J Golman Professor of Medicine in Oncology. "The typical ways we can reduce the effects of the disease also tend to weaken the T cells' ability to attack the cancer. We're looking for a treatment strategy that stops the disease without shutting down T cells' assault on the cancer."

Building upon their past work into the role of JAK1/2 kinases and their signaling pathways in immune cell activation and graft-vs-host disease, the team tested baricitinib and ruxolittinib in mice, finding that the former was more effective in reducing and preventing graft-versus-host disease and even boosted the efficacy of donor T cells in fighting cancer.

"We don't know yet exactly how this happens, but we're working to understand it," remarked first author Dr Jaebok Choi, Assistant Professor of Medicine. "We think at least part of the explanation is the drug strips the leukaemia cells of their immune defences, making them more vulnerable to attack by the donor T cells. At the same time, the drug also stops the donor T cells from being able to make their way to important healthy tissues, such as the skin, liver and gastrointestinal tract, where they often do the most damage."

Baricitinib also increased levels of specific immune cells which can temper immune response and prevent graft-versus-host disease from worsening. These effects appear to be unique to the drug, and were not observed in other JAK inhibitors.

"We were surprised to achieve 100% survival of mice with the most severe model of graft-versus-host disease," Choi added. "We are now studying the multi-pronged ways this drug behaves in an effort to develop an even better version for eventual use in clinical trials."

Register as Visitor to CPhI China 2018!