(RxWiki News) A medication that treats a type of leukemia targets a protein that’s involved in the spread of breast cancer. Combining this medication with a standard breast cancer therapy helped some patients live longer.
In a phase ll clinical trial, researchers found that adding the leukemia medication Sprycel (dasatinib) to the hormone blocker Femara (letrozole) expanded the time advanced breast cancer patients had stable disease.
The combination therapy doubled the period during which the disease did not get worse (progression-free survival) in women with hormone sensitive metastatic (has spread) cancer.
"Ask your oncologist about combination therapies."
This trial, conducted by Dev Paul, DO, PhD, breast oncologist at US Oncology and Rocky Mountain Cancer Centers in Denver, Colorado, and colleagues was designed to investigate therapies that could expand both the quantity and quality of life for advanced breast cancer patients.
Sprycel is approved by the US Food and Drug Administration (FDA) to treat a blood cancer called chronic myelogous leukemia (CML). The medication targets and blocks a protein called Src, which researchers have discovered plays a role in breast cancer metastasizing to the bones — one of the first places the disease spreads.
Femara is what’s called an aromatase inhibitor (AI) and is given to postmenopausal breast cancer survivors following primary treatment to block estrogen production.
The researchers enrolled 120 postmenopausal women in this trial. The women had either recurrent (had returned) or metastatic breast cancer. The tumors were estrogen-receptor positive, meaning the cancer was fed by the hormone estrogen, and HER2-negative, meaning the HER2 protein that makes breast cancers particularly aggressive was not present.
Participants were randomly assigned to receive either Femara alone (63 participants) or Femara and Sprycel (57 participants).
Those receiving the combination therapy took 2.5 mg of Femara and 100 mg of Sprycel twice a day on 28-day cycles. Women in the other group took the same dosages of Femara twice daily.
Participants were allowed to switch to the other group upon disease progress or inability to tolerate the medication(s).
While the combination treatment did not reach the study’s defined endpoint, the researchers discovered that the two medications did significantly extend progression-free survival.
Women taking both medications had a progression-free survival of 22 months, compared to 11 months for women taking Femara alone.
The combination therapy did result in more side effects, the most common of which were fatigue, nausea, anemia, rash, fluid in the lungs and edema or swelling.
Dr. Paul said in a statement, "Although these data suggest that adding dasatinib to letrozole improves progression-free survival for postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer, we would like to find a biomarker for Src activity in the breast before conducting larger clinical studies of this drug combination.”
Results from this trial were presented at the 2013 San Antonio Breast Cancer Symposium. It should be noted that research is considered preliminary before being published in a peer-reviewed journal.
This study was supported by funds from Bristol-Myers Squibb, the maker of both medications studied in this trial. Two of the authors disclosed financial ties with Bristol-Myers Squibb, and one of these authors also received funds from another pharmaceutical manufacturer.