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 Kaposis 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.
"Were 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.