A drug approved by the US Food and Drug Administration (FDA) in 2016 for treating elderly patients with cancer of the blood and bone marrow has been proved to be significantly more effective than standard therapy, say researchers.

The drug, ibrutinib, attacks cancer cells without damaging normal cells, thus causing fewer side effects for patients with chronic lymphocytic leukemia (CLL), said researchers from Loyola University Chicago. CLL, a disease of the immune system, is the most common form of leukemia. It affects mainly older adults, with the average age of diagnosis around 70. The risk is higher in men.

The drug, taken as a pill once a day, is much more convenient than the standard treatment requiring the patient to come in three times a month for infusions and an injection. "Ibrutinib should become the new standard of care," said Scott Smith, Professor and an oncologist at Loyola's Stritch School of Medicine. 

Until now, the standard treatment has been a combination of a chemotherapy drug (bendamustine) that kills cancer cells and an immunotherapy drug (rituximab) that suppresses the immune system. But the study, published in The New England Journal of Medicine, found that 87 per cent of patients receiving ibrutinib alone for two years were alive without any disease progression, compared with 74 per cent of patients who received bendamustine plus rituximab. 

There was no significant difference between patients receiving ibrutinib alone and those receiving ibrutinib plus rituximab. About 17 per cent of patients who received ibrutinib alone experienced an irregular heartbeat called atrial fibrillation. But overall, the drug caused fewer side effects than the standard treatment, Smith said.

For the study, the team included 547 CLL patients (67 per cent male). All were older than 65. Additional studies of ibrutinib are underway in CLL patients younger than age 65, Smith said.