New Targeted Therapy for a Rare Lymphoma 

The FDA granted accelerated approval to the BTK inhibitor pirtobrutinib for the treatment of mantle cell lymphoma.  

The U.S. Food and Drug Administration (FDA) has granted accelerated approval to pirtobrutinib (Jaypirca) for the treatment of adult patients with mantle cell lymphoma (MCL) that has progressed following at least two lines of systemic therapy, including a Bruton’s tyrosine kinase (BTK) inhibitor. 

Pirtobrutinib is a type of targeted therapy called a kinase inhibitor. It blocks the activity of BTK, a protein that promotes the growth and proliferation of B cells, the cell of origin for many blood cancers, including MCL. Although other BTK inhibitors are approved to treat MCL, pirtobrutinib is the first that does not form a permanent bond with BTK, and it has been shown to have higher affinity for BTK than its predecessors. 

The approval was based on results from BRUIN, an open-label, multicenter, single-arm, phase I/II clinical trial in which 120 patients with MCL were treated with ibrutinib until disease progression or unacceptable toxicity. All patients had previously received a BTK inhibitor, and 93 percent of patients had received at least two prior lines of therapy. 

The overall response rate was 50 percent, and 13 percent of patients experienced a complete response. The estimated median duration of response was 8.3 months. 

MCL is a relatively rare form of non-Hodgkin lymphoma, with an incidence of around 1 in every 200,000 Americans. 

The FDA rendered its decision on January 27, 2023. Accelerated approval means that continued approval may be contingent upon a confirmatory trial.