An available drug called zanubrutinib resulted in 80 percent of patients’ cancers shrinking in a new clinical trial, suggesting the treatment is promising in treating a type of cancer that does not typically respond to chemotherapy. 

Used against lymphoma, one of the most common types of cancer in the US, the drug may be effective against the slow-moving but tough-to-treat cancer, filling an important gap in viable treatment options. 

The results were published in the journal Blood Advances.

Lymphoma is a type of cancer that begins in the lymphatic system – which controls the production of white blood cells used in the immune system. The two main types are Hodgkin’s lymphoma and non-Hodgkin's lymphoma, which can vary in treatability from relatively simple, to problematic.  

In the study, researchers from the University of Michigan looked into follicular and marginal zone lymphoma, in which immune B cells begin to divide uncontrollably and form tumors. These cancers do not respond well to chemotherapy, leaving them difficult to treat.

Turning to an existing drug currently used to treat another type of lymphoma, the researchers aimed to test the use of zanubrutinib against a wider array of cancers, and recruited 20 patients with marginal zone lymphoma and 33 patients with follicular lymphoma. Zanubrutinib inhibits a signaling enzyme called BTK that B cells are reliant on, preventing them from spiraling out of control in lymphoma patients. 

Each patient received a dose of zanubrutinib in an open-label trial (not ideal in this type of clinical trial, but significantly cheaper than double-blind, controlled options).  

Of the marginal zone lymphoma patients, 80 percent saw their tumors shrink and 20 percent saw clinical remission, where no cancer was present on imaging tests. The results for follicular cancer were not as promising, with just 36.4 percent showing a response, but still around 18 percent showed no cancer at the follow-up appointment. 

There were no serious adverse events, though there were some adverse effects including diarrhea, bruising, and lower white blood cell counts. 

The results suggest an impressive response for the drug against marginal zone lymphoma in particular and a larger, more controlled trial is now needed to confirm the findings. 

“Treatment options with improved tolerability and better disease control were much needed for marginal zone lymphoma and follicular lymphoma,” said Tycel Phillips, a hematologist at the Rogel Cancer Center and the lead author of the study, in a statement.  

“While the small size of this study limits broad conclusions, the safety and efficacy results highlight the potential for zanubrutinib as an addition to available therapies for these cancers.”