According to the National Cancer Institute, there were an estimated 48,610 new cases of leukemia last year, with 23,720 deaths from the condition. Now, new research suggests that a pill taken twice daily could turn the blood cancer into a treatable disease and allow patients to avoid chemotherapy.
The team, led by researchers from Weill Cornell Medical College in New York, focused their research on chronic lymphocytic leukemia (CLL) – the second most common form of the disease among adults.
CLL is a blood and bone marrow disease that can occur when the bone marrow makes an excessive amount of lymphocytes – a type of white blood cell.
These lymphocytes become abnormal and are unable to effectively stave off infection. The increased number of these blood cells also leaves limited room for healthy white blood cells, red blood cells and platelets. This can cause anemia, infection and easy bleeding.
CLL is usually treated with chemotherapy drugs. Although the majority of patients respond to these drugs, the researchers say most patients relapse and need repeated cycles of the treatments.
With each cycle, the remission periods tend to decrease. The researchers say that as a result, patients often stop responding to treatment or are forced to stop because of severe side effects.
According to the investigators, these side effects are a result of the chemotherapy medication being unable to distinguish between healthy cells and cancer cells.
With this in mind, the research team set out to find an alternative treatment.
‘Remarkable’ results for idelalsib
For their study, published in The New England Journal of Medicine, the researchers tested a combination of two targeted medications – drugs that can attack cancer cells without damaging healthy cells – on 220 patients with CLL who were not able to undergo chemotherapy.
The combination treatments were:
- Rituximab and idelalsib, or
- Rituximab and a placebo pill.
The researchers found that compared with the group who received rituximab and a placebo pill, patients who received rituximab and idelalsib avoided disease progression for a longer period of time.
When monitoring the patients 6 months after treatment, 93% of patients who received treatment with rituximab and idelalsib did not suffer disease progression, compared with 46% of patients who were treated with rituximab and a placebo.
Furthermore, the investigators found that 81% of patients responded to treatment with rituximab and idelalsib, while only 13% responded to treatment with rituximab and a placebo.
And 1 year after the baseline of the study, 92% of patients treated with rituximab and idelalsib were still alive, compared with 80% of rituximab and placebo patients.
The research team says that the combination of rituximab and idelalsib proved so successful in patients that the study was stopped early in order to prescribe all patients the treatment.
Commenting on the findings, Dr. Richard Furman, of Weill Cornell Medical College and lead researcher of the study, says:
“We saw incredible responses in patients who used idelalisib. Their cancer quickly melted away. These types of responses were even seen in patients who didn’t respond to chemotherapy.”
Dr. Furman notes that chemotherapy-resistant patients tend to be the most difficult patients to treat. But he says that even these patients responded to the treatment within 1 week.
‘These drugs will change patients’ lives’
These new findings follow on from a phase II clinical trial that the team conducted last year, which found that ibrutinib – also a targeted cancer drug – was effective against mantle cell lymphoma. This is a rare form of leukemia.
Dr. Furman has already been using ibrutinib as the first treatment option for patients, allowing them to avoid chemotherapy completely.
He says that these most recent findings, combined with his past research, suggest that ibrutinib and idelalisib may overtake chemotherapy as the preferred treatment option for leukemia.
“These drugs will change the lives of many patients. Given the long-term toxicities of chemotherapy, leading to bone marrow failure, infections and death, moving this therapy up front in the treatment algorithm and providing it to all patients is the next step.”