Open Enrollment for Phase 1 Trial Testing CS1-CAR T-Cell Therapy for Hard-to-Treat Myeloma

A Phase 1 clinical trial is recruiting patients with hard-to treat or relapsed multiple myeloma to evaluate Mustang Bio’s investigational autologous (patient-derived) CS1-chimeric antigen receptor (CAR) T-cell therapy.

The trial (NCT03710421), designed to assess the therapy’s safety and tolerability, is being conducted at the City of Hope National Medical Center in Duarte, Calif.

Researchers will evaluate the ability of transplanted CS1 T-cells to proliferate and persist in the body. The study also will assess the therapy’s clinical impact on people with multiple myeloma who have failed to respond to treatment, or whose disease came back after three different treatments.

Autologous CAR T-cell therapy consists of collecting a patient’s own immune cells, using a technique called leukapheresis, and modifying them in the lab to specifically recognize a protein that is present in cancer cells. These modified T-cells are expanded to several million in the lab, and then injected back into the patient to fight the tumor.

Mustang Bio’s new investigational cell therapy, called MB-104, was developed to target the CS1 protein (also named SLAMF7), which is found at higher levels in the surface of myeloma cells. This strategy ensures that the therapy is more likely to attack cancer cells and not healthy cells.

“CS1 is a very promising target for multiple myeloma patients who currently have few viable treatment options,” Xiuli Wang, PhD, a professor in the department of hematology and hematopoietic cell transplantation at City of Hope research, said in a press release. Wang’s team developed the CS1 CAR T.

Results from a previous preclinical study showed that a single injection of CS1-CAR T therapy into mice with multiple myeloma led to a marked reduction of tumor burden and prolonged survival in contrast with placebo-treated mice, in which the tumor progressed rapidly.

The Phase 1 trial is expected to enroll approximately 30 adults with confirmed active multiple myeloma who have relapsed or refractory disease after at least three prior treatments.

Participants will undergo an induction treatment regimen with an initial chemotherapy round of three to four weeks, followed by an infusion of the modified CS1-CAR T therapy. Their progress will be followed for 28 days. After that, all patients may undergo a second infusion of the CS1 T-cell, if necessary, to ensure therapeutic levels of the cells in circulation in the body.

During the first month of treatment, participants will be evaluated every week. Afterward, evaluation appointments will be scheduled monthly for one year, and then periodically for up to 15 years.

“This groundbreaking CS1 CAR T trial represents an exciting development for multiple myeloma patients. We look forward to learning more about its potential to address this difficult-to-treat disease,” said Manuel Litchman, MD, president and CEO of Mustang.

The study is expected to be completed by the end of 2021.

For more information about the trial, please visit the study page here.