Zanubrutinib treatment for relapsed or unresponsive chronic lymphocytic leukemia

This study aimed to investigate the safety and effectiveness of zanubrutinib in patients with relapsed/unresponsive chronic lymphocytic leukemia. 

This study concluded that zanubrutinib was well tolerated and with promising effectiveness in these patients.  

Bruton tyrosine kinase (BTK) inhibitors are a type of targeted therapy. They have shown effectiveness in the treatment of cancers such as chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). Zanubrutinb (Brukinsa) is a BTK inhibitor currently under investigation. It was unknown if zanubrutinib was safe and effective in patients with relapsed/unresponsive CLL/SLL.  

This study involved 91 patients with relapsed/unresponsive CLL or SLL. Patients received zanubrutinib as a second-line treatment. They were followed for an average of 15.1 months. The main outcome measured was the overall response rate (ORR).  

84.6 % of patients achieved a response. Of these patients, 3.3% achieved a complete response (CR; the disappearance of all signs of cancer), 59.3% achieved a partial response (tumor shrinkage) and 22% achieved a partial response with lymphocytosis (high number of white blood cells that produce antibodies).   

The estimated 12-month event-free survival (EFS; survival without complications related to the disease) rate for the duration of response was 92.9%. 96% of patients were alive after 1 year.

44% of patients experienced neutropenia (low level of white blood cells) as a side effect. 15.4% experienced a low platelet (blood cells involved in clotting) count and 13.2% had a lung infection or pneumonia. Less common side effects were an upper respiratory tract infection experienced by 9.9% and anemia (low red blood cells) experienced by 8.8% of patients.  

9% of patients stopped treatment with zanubrutinib due to side effects and 8% of patients required at least one dose reduction. 

This study concluded that zanubrutinib was well tolerated and showed promising effectiveness in patients with relapsed/unresponsive CLL/SLL. 

This was a small phase II study. Further larger studies are needed to confirm the effectiveness of this drug. This study was funded by BeiGene, the manufacturer of zanubrutinib.