For the first time, the American Society of Clinical Oncology (ASCO) has announced the Cancer Advance of the Year: the introduction of new therapies that promise to transform the treatment of chronic lymphocytic leukemia (CLL), the most common form of adult leukemia.
Four new agents have recently received U.S. Food and Drug Administration (FDA) approval for treatment of CLL: two immunotherapy drugs, obinutuzumab and ofatumumab, given in combination with chemotherapy for previously untreated CLL, and two molecularly targeted drugs, ibrutinib and idelalisib, for treatment-resistant or relapsed CLL.
“These new therapies fill an enormous need for thousands of patients living with CLL,” said Gregory Masters, MD, FACP, of the Helen F. Graham Cancer Center in Newark, DE, who is a co-executive editor of the report. “For many older patients, especially, these drugs essentially offer the first chance at effective treatment, since the side effects of earlier options were simply too toxic for many to handle.”
Approximately 15,000 people in the United States, most over age 55, are diagnosed with CLL each year, and approximately 4,600 die of the disease.
The standard treatment for CLL has been a combination of chemotherapy with fludarabine/cyclophosphamide and immunotherapy with rituximab. Although effective in otherwise healthy patients, this regimen does not prolong survival in patients with other medical illnesses and is poorly tolerated by most patients.
New Options for Newly Diagnosed CLL
In late 2013 and early 2014, two immunotherapy agents received FDA approval for combination treatment with chlorambucil for newly diagnosed CLL.
Approval of obinutuzumab, which targets the CD20 antigen, followed a trial of 781 patients with CLL who had significant coexisting medical conditions.1
The combination of obinutuzumab plus chlorambucil more than doubled progression-free survival compared with chlorambucil alone, from 11.1 months to 26.7 months, and significantly prolonged overall survival. The obinutuzumab-chlorambucil combination was also superior to rituximab-chlorambucil, with prolonged progression-free survival and higher rates of complete response.
Ofatumumab, another immunotherapy agent targeting CD20, had previously been approved for treatment of patients with CLL resistant to standard chemotherapy. Its approval for first-line treatment of CLL was based on a study of 447 previously untreated patients for whom fludarabine-based therapy was inappropriate.2
Ofatumumab plus chlorambucil produced a significantly higher overall response rate than chlorambucil alone and increased progression-free survival from 13.1 months to 22.4 months.