Researchers Developing Less Toxic Therapy to Target Breast Cancer Cells

University of California, San Francisco, researchers have received approval from the National Cancer Institute (NCI) to develop a less toxic breast cancer therapy that may also prove to be more efficient at directly targeting cancer cells.

The UCSF team have found a way to combine liposomes with antibodies that can recognize and bind to cancer cells. The combination of the two, called immunoliposomes, has been compared to the "smart bombs" of the Gulf War in their ability to selectively target and kill cancer cells, while avoiding normal cells. "We have completed ‘proof of concept’ studies and they have shown that this therapy cures tumors in mice," said John Park, MD, assistant adjunct professor of medicine.

By putting chemotherapy in liposomes and adding the targeting capability of a specially developed antibody, the drugs go directly to the cancer cells without causing more toxic side effects. "The antibodies bind to the cancer cell, enter it, and release the drugs inside," said Dr. Park.

Liposomes themselves were recently approved by the FDA for delivering drugs to patients with Kaposi’s sarcoma. They are also being evaluated in clinical trials in breast cancer.

Immunoliposomes May Be More Efficient Than Liposomes Alone

The addition of an antibody to liposomes represents a potential improvement of liposome technology, according to the UCSF team. The researchers have found that immunoliposomes, rather than liposomes, efficiently find and enter cancer cells, thereby increasing their effectiveness. The antibodies on these liposomes recognize the HER2/neu (erB2) protein on cancer cells.

 "We’re not just targeting the protein, but bringing a payload of chemotherapy to the cancer cells," Dr. Park said. The payload is the standard chemotherapy drug doxorubicin. Compared with infusions of chemotherapy alone, the doxorubicin-loaded anti-HER2/neu immunoliposomes are more effective at inhibiting tumor growth--including cures in mice--and cause fewer side effects, he added.