A large trial has just been launched in the UK exploring the use of stem cells for treating patients with Crohn's disease. The radical treatment involves essentially "rebooting" a patient's immune system and has been used successfully in the past for multiple sclerosis and some cancers.

Crohn's disease is a chronic inflammatory bowel disease with no clearly understood cause. In severe cases it results in devastating and debilitating symptoms, and rates of diagnoses are increasing in Western countries. A variety of treatments are available to battle the disease, but they often don't work consistently and can have problematic side effects.

"Despite the introduction of new drugs, there are still many patients who don't respond, or gradually lose response, to all available treatments," explains James Lindsay, one of the researchers working on the upcoming trial. "Although surgery with the formation of a stoma may be an option that allows patients to return to normal daily activities, it is not suitable in some and others may not want to consider this approach."

The treatment being trialed is called hematopoietic stem cell transplantation (HSCT). The first step in the process is to administer a combination of hormones and chemotherapy to stimulate stem cell production. Originating in a person's bone marrow, these stem cells spill into the bloodstream where they are harvested and stored for later use.

Patients are then administered an aggressive bout of chemotherapy, designed to kill off the incorrectly functioning immune system. The stem cells are subsequently transplanted back into the patient, generating a new immune system and eliminating the prior faulty immune memory that resulted in the body attacking healthy cells.

The same team previously completed a smaller preliminary trial using the process for Crohn's back in 2015. That trial was not entirely successful, with a variety of serious adverse effects noted, but many patients did report significant clinical improvements signaling to the researchers that a broader follow-up trial would be worthwhile. It is claimed that better supportive care and alterations of drug dosages should reduce adverse events in the new trial.

The goal of the trial isn't explicitly to induce a cure in patients but that is certainly one of the hopes. One of the key biologic therapies currently utilized in Crohn's disease can often reduce in efficacy over time as the body develops antibodies against the treatment. In the earlier small study it was found that 80 percent of those patients that didn't reach remission through the new treatment did at least regain efficacy using therapies that had previously become ineffective.

"We're hoping that by completely resetting the patient's immune system through a stem cell transplant, we might be able to radically alter the course of the disease," says Lindsay, "While it may not be a cure, it may allow some patients to finally respond to drugs which previously did not work."

The trial is planned to have a long four- to seven-year follow up period to better understand the long-term effects of the stem cell treatment, but initial results are expected to be published around 2022.

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