The FDA on Friday approved a Gilead Sciences drug developed for treating mantle cell lymphoma, paving the way for the company to commercialize its second cancer cell therapy.
Approval for the drug, brexucabtagene autoleucel (Tecartus), covers patients whose cancer has relapsed or has not responded to earlier treatments. Gilead (NASDAQ: GILD) added the therapy to its pipeline via its $12 billion acquisition of Kite Pharma in 2017, a deal headlined by Yescarta, a cell therapy that went on to win approval later that year in non-Hodgkin lymphoma. Both Yescarta and Tecartus are chimeric antigen receptor (CAR) T cell therapies.
Mantle cell lymphoma is a rare form of non-Hodgkin lymphoma that arises in immune cells called B-cells. This cancer develops in a part of the lymph node called the mantle zone. Though mantle cell lymphoma starts in the lymph nodes it can quickly spread to the rest of the body. It primarlily affects men age 60 or older.
CAR-T therapies are made by removing a patient’s immune cells, engineering them in a lab to better recognize and fight cancer, and then reinfusing those cells into the patient. Tecartus is designed to target CD19, a protein found in high amounts in cancerous B cells. Friday’s regulatory decision makes Tecartus makes the first FDA-approved cell therapy for mantle cell lymphoma.
The FDA based its ruling on an open label study that enrolled 74 mantle cell lymphoma patients who had previously been treated with chemotherapy, an antibody therapy that blocks the cancer protein CD20, and the cancer drugs ibrutinib or acalbrutinib. The main goal was to show improvement in objective response, which was defined as the combination of complete responses (the disappearance of all signs of the cancer) and partial responses (signs of the cancer were minimized, but did not go away).
Of the 60 patients that could be evaluated, the FDA says the objective response rate was 87 percent. Signs of the cancer completely disappeared in 62 percent of patients.
The most common side effects observed in the studies were infections, low blood cell counts, and a weakened immune system. But the FDA cautions that the therapy can have toxic and potentially life-threatening effects on the brain. According to the clinical trial results, neurologic events occurred in 81 percent of patients; in 37 percent, the problems were severe enough to require hospitalization or some other medical intervention. Those brain problems lasted a median of three weeks and were resolved for 79 percent of patients in the study. But three patients had ongoing neurologic problems when they died, including one who had serious brain issues.
The therapy can also cause a severe immune system reaction called cytokine release syndrome, which is a response to the activation and proliferation of CAR-T cells. This syndrome can cause a fever and flu-like symptoms, and in severe cases can lead to death. In 85 percent of patients treated in the study, the first cytokine or neurological problems were observed within a week of the receiving the drug.
The cytokine release syndrome and neuologic toxicities are flagged in a black box warning on Tecartus’s label. The FDA approval requires Gilead to offer a program that informs physicians and patients about the drug’s risks. Gilead says that its program for Tecartus will be added to an existing one for Yescarta, and provided as a single offering. The FDA approval also requires Gilead to conduct a post-marketing study to evaluate the long-term safety of the drug.
Gilead is testing Tecartus to see if it can treat additional cancers. Ongoing clinical trials are evaluating the cell therapy in acute lymphoblastic leukemia and chronic lymphocytic leukemia.
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