A revolutionary treatment for cancers may also be able to treat and reset the immune system to provide long-term remission or possibly even cure certain autoimmune diseases.
Chimeric antigen receptor (CAR) T-cell therapy has offered a novel approach to treating hematologic cancers since 2017, but there are early signs that these cellular immunotherapies could be repurposed for B-cell mediated autoimmune diseases.
In September of last year, researchers in Germany reported that five patients with refractory systemic lupus erythematosus (SLE) treated with CAR T-cell therapy all achieved drug-free remission. At the time of publication, no patients had relapsed for up to 17 months after treatment. The authors described seroconversion of antinuclear antibodies in two patients with the longest follow-up, “indicating that abrogation of autoimmune B-cell clones may lead to a more widespread correction of autoimmunity,” the researchers write.
In another case study published in June, researchers used CD-19 targeted CAR-T cells to treat a 41-year-old man with refractory antisynthetase syndrome with progressive myositis and interstitial lung disease. Six months after treatment, there were no signs of myositis on MRI and a chest CT scan showed full regression of alveolitis.
John Hopkins Medicine
Dr. Max Konig
Since then, two biotechnology companies – Cabaletta Bio in Philadelphia and Kyverna Therapeutics in Emeryville, Calif. – have already been granted fast-track designations from the U.S. Food and Drug Administration for CAR T-cell therapy for SLE and lupus nephritis. Bristol-Myers Squibb is also conducting a phase 1 trial in patients with severe, refractory SLE. Several biotechnology companies and hospitals in China are also conducting clinical trials for SLE. But this is only the tip of the iceberg regarding cellular therapies for autoimmune disease, said Max Konig, MD, PhD, an assistant professor of medicine in the division of rheumatology at Johns Hopkins University, Baltimore.
“It’s an incredibly exciting time. It’s unprecedented in the history of autoimmunity,” he noted.
A ‘reboot’ for the immune system
B-cell targeted therapies have been around since the early 2000s with drugs like rituximab, a monoclonal antibody medication that targets CD20, an antigen expressed on the surface of B cells. The CAR T cells currently available target another surface antigen, CD19, and are a much more potent therapy. Both are effective at depleting B cells in blood, but these engineered CD19-targeted T cells can reach B cells sitting in tissues in a way that antibody therapies cannot, Dr. Konig explained.
“If you have a patient with myositis, for example, where autoreactive B cells are sitting in the inflamed muscle, or a patient with rheumatoid arthritis, where you have disease-relevant B cells in hard-to-reach tissues like the synovium, those cells are much harder to deplete with an antibody, compared to a T cell that evolved to surveil and effectively kill in all tissues,” he explained.
In this process, T cells are collected from patients via leukapheresis and then re-engineered to express chimeric antigen receptors. A few days before these modified T cells are infused back into the patient, the patients are given a low-dose chemotherapy (lymphodepletion) regimen to help increase the effectiveness of the therapy. The one-time infusion is generally given on an inpatient basis, and patients are then monitored in hospital for side effects.
Once B cells are depleted, disease symptoms improve. But in the case studies published to date, once B cells re-emerge, they are naïve and no longer producing autoreactive B cells.
Dr. Carl June
“Maybe it’s like a tabula rasa: You wipe [the B cells] out and start with a clean slate. Then, the immune system reboots, and now it’s working, whereas before it was messed up,” said Carl June, MD, who directs the Center for Cellular Immunotherapies at the at the University of Pennsylvania, Philadelphia. Dr. June and his research team led the development of CAR T-cell therapies for blood cancers.
The findings suggest that autoantibodies “might not be hardwired into the immune system,” he said.
But Dr. Konig stressed that we are still in the early days of clinical trials, and more research is necessary to understand the safety and efficacy of these therapies.
“There’s an incredible buzz around CAR T cells at the moment in rheumatology, which is great because I think that’s where the future is,” he said. “But we still need to learn how to appropriately apply these therapies in randomized, controlled trials.”
So far, the evidence behind CD19 CAR T-cell therapies in autoimmune disease is from case studies and phase 1 trials in a very small number of selected patients. (The upcoming Cabaletta and Kyverna trials in lupus will also be small, consisting of 12 patients each.)