In late October, CRISPR Therapeutics announced positive top-line data from a Phase 1 clinical trial that was analyzing CTX110 for patients with CD19+ B-cell cancers. However, according to an article on Biospace, there might be a potential safety issue. CRISPR announced the data from the Phase 1 CARBON trial on their website, but there is one thing to face: a patient death during the trial. So in this article, Patient Worthy will attempt to unpack what CAR-T therapy is and whether or not it is actually safe.
CRISPR CAR-T Therapy
What is CAR-T Therapy?
According to the American Cancer Society (ACS), CAR-T therapy, or:
Chimeric antigen receptor (CAR) T-cell therapy is a promising new way to get immune cells called T cells (a type of white blood cell) to fight cancer by changing them in the lab so they can find and destroy cancer cells. CAR T-cell therapies are sometimes talked about as a type of gene or cell therapy, or immune effect cell therapy.
So this works by collecting blood from a patient. Next, doctors remove T-cells and modify them to create CARs. Finally, these specialized T-cells are placed back into the body. They are able to bind to an antigen on the surface of tumor cells, causing tumor cell growth and preventing tumor development.
In the case of CRISPR’s CTX110, the therapy is allogeneic as opposed to autologous. This means that rather than being sourced from the patients themselves, the CAR-T cells are sourced from a healthy donor. Currently, there are few (if any) allogeneic CAR-T therapies. However, there are two approved autologous therapies – Kymriah and Yescarta.
During the Phase 1 CARBON trial, CRISPR evaluated varying doses of CTX110 for patients with B-cell lymphoma and transformed follicular lymphoma. Overall, CTX100 was effective in prompting anti-tumor responses. However, there are some serious safety issues discovered in the trial.
Three patients experienced moderate or mild cytokine release syndrome (CRS). The National Cancer Institute (NCI) describes CRS as:
A condition that may occur after treatment with some types of immunotherapy, such as monoclonal antibodies and CAR-T cells. Cytokine release syndrome is caused by a large, rapid release of cytokines into the blood from immune cells affected by the immunotherapy.
Symptoms of CRS include headache, fever, nausea, rashes, difficulty breathing, low blood pressure, and an extremely fast heartbeat. However, these three patients experienced symptom reduction after taking tocilizumab.
One patient experienced moderate (Grade 2) Immune Effector Cell-Associated Neurotoxicity Syndrome. This also resolved after treatment.
However, one patient died during the course of the trial. This patient first experienced CRS, then later febrile neutropenia. Neutropenia relates to a low level of white blood cells called neutrophils in the blood. The febrile version is when neutropenia occurs alongside fever, and can be dangerous if left untreated. The patient had memory loss and confusion. Eventually, he required intubation and later passed. This occurred shortly under 2 months after receiving CTX110. But it is important to note that this patient was immunocompromised, older, and had a more severe form of cancer.
Researchers hope to continue studying CTX110 in larger group settings. Ultimately, this will help decide and solidify the understanding of the therapy’s safety, efficacy, and tolerability.