Chemotherapy given in low, frequent doses a novel strategy called "metronomic" delivery achieved partial shrinkage of disease in some advanced breast cancer patients when given concurrently with an angiogenesis inhibitor.
In a pilot study of 55 patients, the combination of low-dose chemotherapy and the anti-VEGF antibody, Bevacizumab ( Avastin ) delayed the breast cancer's progression by an average of 5 ½ months, compared to two months with the low-dose chemotherapy alone, said Harold Burstein, at Dana-Farber.
" Pairing metronomic therapy with a dedicated angiogenesis inhibitor showed clinical activity, and was quite well tolerated," said Burstein. "We think this is a combination worth pursuing and are exploring this treatment concept further in a Phase II study, which extends these treatments into early stage breast cancer therapy."
The current study is one of the first rigorous tests of a treatment strategy that was proposed several years ago as a means of improving the results of chemotherapy for breast cancer, said Burstein.
Historically, high doses of chemotherapy are given at intervals of two to three weeks, with time off the drug to recover from side effects. However, laboratory researchers have suggested that this rest period also allows the blood vessels feeding the tumor to re-form after they had been destroyed by the chemotherapy. They proposed giving smaller, almost constant doses of the drug as regular as the ticking of a metronome as a way to hamper angiogenesis.
In the Dana-Farber study, the chemotherapy drugs Cyclophosphamide and Methotrexate were given in a metronomic regimen to 21 patients with advanced, metastatic breast cancer.
In another 34 patients, the chemotherapy was paired with the angiogenesis inhibitor Bevacizumab given intravenously every 14 days. None of the patients had been previously heavily treated for their advanced cancer.
The metronomic-alone therapy led to two partial responses ( 10 percent of the patients ), while in another eight patients the cancer remained stable. Results seemed better in the combination group, in which 10 patients ( 29 percent ) had partial responses, while 14 ( 41 percent ) experienced stable disease.
There were still some side effects in both groups, including fatigue, but Burstein said the therapies were generally well tolerated and lacked the major side effects of traditional chemotherapy such as gastrointestinal and hair loss.
The researchers concluded that the metronomic therapy by itself had limited clinical activity, but the activity seen when the anti-angiogenesis drug was added suggests "further investigation of this novel treatment study is warranted."
Source: Dana-Farber Cancer Institute, 2005