FDA fast tracks birelentinib for certain hard-to-treat blood cancers
Goal is to speed treatment for relapsed, refractory CLL/SLL
The U.S. Food and Drug Administration (FDA) granted fast track designation to birelentinib as a potential treatment for certain forms of blood cancer.
The designation applies to birelentinib’s use in people with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) that is relapsed or refractory — meaning the disease has come back or failed to respond to other treatments — after at least two prior lines of blood cancer treatment, including a BTK inhibitor and a BCL-2 inhibitor.
The FDA gives fast track status to experimental medicines that have the potential to fill unmet medical needs, with the goal of speeding the development of new treatments that may be important. The designation gives developer Dizal Pharmaceutical access to perks like more frequent communication with the FDA during the drug development process.
“The granting of fast track designation underscores the U.S. FDA’s recognition of birelentinib’s potential to address an unmet medical need in patients with CLL/SLL,” Xiaolin Zhang, PhD, CEO of Dizal, said in a company press release. “We look forward to working closely with the FDA to accelerate the global clinical development of birelentinib and bring this treatment option to patients as quickly as possible.”
Targeting proteins to halt cancer cell growth
CLL/SLL refers to blood cancers marked by the abnormal growth of certain types of immune cells. It’s generally treated with medications that block the activity of BTK and BCL-2, two proteins that drive cancer cell growth by activating a molecular system called the BCR signaling pathway. When patients are relapsed or refractory to these therapies, it usually means that the cancer has evolved mechanisms that let it resist inhibitors of BTK and/or BCL-2.
According to Dizal, there are two main ways that cancer cells typically evolve to develop such resistance: either the BTK protein acquires a specific mutation called C481X, or cells start to activate the BCR signaling pathway through other mechanisms that don’t involve BTK. Either way, the end result is that the BCR signaling pathway remains activated despite inhibitors of BTK/BCL-2, so cancer cells continue to grow.
Birelentinib is designed to block the activity of BTK and another protein called LYN. By inhibiting both proteins at the same time, it aims to shut down all activation of the BCR signaling pathway, whether dependent on BTK or not. By shutting down this pathway, the therapy aims to halt the growth of cancer cells.
The FDA’s decision to give fast track designation to birelentinib was supported by data from Phase 1/2 studies that tested the therapy in people with CLL/SLL who had previously received treatments targeting BTK. According to Dizal, 84.2% of patients responded to the therapy, and the treatment was generally safe. The benefits were also long-lasting, with about 83% of patients still responding after nine months.
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