All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we look at a way of making blood stem cell transplants safer and more readily available
Blood stem cell transplants have provided lifechanging treatments to individuals. This statement is observed firsthand in several patients in CIRM funded trials for X-linked Chronic Granulomatous Disease (X-CGD), Sickle Cell Disease (SCD), and Severe Combined Immunodeficiency (SCID). The personal journeys of Evangelina Padilla-Vaccaro, Evie Junior, and Brenden Whittaker speak volumes for the potential this treatment holds. In these trials, defective blood stem cells from the patient are corrected outside the body and then returned to the patient in a transplant procedure.
Unfortunately, there is still a certain degree of risk that accompanies this procedure. Before a blood stem cell transplant can be performed, diseased or defective blood stem cells in the patient’s bone marrow need to be removed using chemotherapy or radiation to make room for the transplant. This leaves the patient temporarily without an immune system and at risk for a life-threatening viral infection. Additionally, viral infections pose a serious risk to patients with immune deficiency disorders, with viruses accounting upwards of 40% of deaths in these patients.
That’s why in October 2017, the CIRM ICOC Board awarded $4.8M to fund a clinical trial conducted by Dr. Michael Pulsipher at the Children’s Hospital of Los Angeles. Dr. Pulsipher and his team are using virus-specific T cells (VSTs), a special type of cell that plays an important role in the immune response, to treat immunosuppressed or immune deficient patients battling life-threatening viral infections. This trial includes patients with persistent viral infections after having received a blood stem cell transplant as well as those with immune deficiency disorders that have not yet received a blood stem cell transplant. The VSTs used in this trial specifically treat cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus infections. They are manufactured using cells from healthy donors and are banked so as to be readily available when needed.
One challenge of receiving a stem cell transplant can be finding a patient and donor that are a close or identical match. This is done by looking at specific human leukocyte antigens (HLA), which are protein molecules we inherit from our parents. To give you an idea of how challenging this can be, you only have a 25% chance of being an HLA identical match with your sibling.
Because VSTs are temporary soldiers that are administered to fight the viral infection and then disappear, Dr. Pulsipher and his team are using partially HLA-matched VSTs to treat patients in their trial. Previous studies have indicated that partially HLA-matched T-cells can be effective in treating patients. The availability of partially HLA-matched VST banks that can be used “off the shelf” improves accessibility and shortens the time for patients to receive VST therapy, which will save lives.
To learn more about Dr. Pulsipher’s work, please view the video below: