In a breakthrough trial, a new cancer drug was shown to eliminate leukemia in almost a quarter of the treatment group, raising hope for improved therapy and prevention strategies against the cancer that currently kills thousands of Americans each year.

The trial, which was conducted by researchers at the Walter and Eliza Hall Institute in Melbourne, Australia, involved 67 patients diagnosed with advanced chronic lymphocytic leukemia (CLL). Preliminary figures suggest that the newly developed drug ABT-199 completely eliminated cancer in 23 percent of the subjects. In addition, it induced partial remission in 61 percent of patients. The findings were presented at the annual meeting of the American Society of Hematology in New Orleans.

According to John Seymour, chair of hematology at Australia’s Peter MacCallum Cancer Institue, the results of the trial are unprecedented. "Patients on the trial were typically incurable, with an average life expectancy of up to 18 months,” he said, speaking to the Sidney Morning Herald. “So to see complete clearance of cancer in nearly one-quarter of these patients after taking this single therapy is incredibly encouraging."

The new drug, which is taken as a pill, helps kill cancer by targeting Bcl-2 — a protein believed to protect cancer cells from cytotoxic treatment like chemotherapy and radiotherapy. Given the drug’s innovative mechanism of action, the researchers believe that it will yield similar results in trials involving other types of aggressive cancer, such as lymphomas, prostate cancer, and breast cancer.

A phase two trial to assess its safety and effectiveness in a larger treatment group is already underway. If the trial is successful, a finished product could receive federal approval within three years. "It is still very early in the development of the drug and learning how to best give it is still ahead of us but the early signals are profoundly encouraging,” Seymour told reporters.

Chronic lymphocytic leukemia is a cancer of the blood and bone marrow that currently kills about 5,000 Americans each year. In Australia, it is the most common type of leukemia. Although the condition is typically not associated with any early symptoms, some patients report enlarged lymph nodes, frequent infections, weight loss, and pain caused by an enlargement of the spleen. To learn more about leukemia, lymphoma, and myeloma, visit the Leukemia & Lymphoma Society's online database.

Source: Seymour JF, Davids MS, Pagel JM, et al. Bcl-2 inhibitor ABT-199 (GDC-0199) monotherapy shows anti-tumor activity including complete remissions in high-risk relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). [Presented at: 55th ASH Annual Meeting]. December 7-10, 2013.