Research at Northwestern University Feinberg School of Medicine played a significant role in Food and Drug Administration approval of Abraxane (paclitaxel protein-bound particles for injectable suspension), indicated for the treatment of metastatic breast cancer. “The approval means that women with metastatic breast cancer no longer need to endure the toxicities associated with solvents and will no longer need steroid premedication when they receive this albumin-bound form of paclitaxel,” said principal clinical study investigator William J. Gradishar, M.D., associate professor of medicine, division of hematology/oncology at Feinberg and co-director, Lynn Sage Breast Cancer Program at Northwestern Memorial Hospital.
Gradishar is also a breast cancer researcher at The Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
“In our research, participants who no longer responded to some of the more common treatments showed improvement with Abraxane and experienced less-severe side effects that made treatment more tolerable,” Gradishar said.
Abraxane is engineered using a proprietary process (protein-bound nanoparticle technology) to create tiny particles (nanoparticles 100th the size of a red blood cell) in which the active chemotherapeutic drug, paclitaxel, is bound to a naturally occurring protein called albumin.
By using this nanotechnology, the active component (paclitaxel) can be delivered into the body at a 50 percent higher dose over 30 minutes.
This contrasts with Taxol, in which paclitaxel is dissolved in a toxic solvent, which requires pre-medication with steroids and antihistamines to avoid hypersensitivity reactions and must be given in infusions for up to three hours.
Because Abraxane is solvent-free, solvent-related toxicities are eliminated and premedication is not required.
In the clinical studies, the response rate for all participants treated with Abraxane was almost twice that of participants receiving the solvent-based paclitaxel injection. Without toxic solvents, Abraxane could be given at higher doses than Taxol, which may account, in part, for the increased anti-tumor activity.
In addition, albumin is a protein that normally transports nutrients to cells and has been shown to accumulate in rapidly growing tumors. Therefore, Abraxane’s increased effectiveness may also be due to preferential delivery of albumin-bound paclitaxel to cancer cells.
Abraxane was developed by American Bioscience and will be marketed by Abraxis Oncology, a division of American Pharmaceutical Partners.
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The foundation of the new therapy is paclitaxel, a plant derivative that is an effective anti-cancer agent. Delivering paclitaxel to cancerous sites is difficult because it does not dissolve in water or blood. In the past, physicians have dissolved it in modified castor oil for injection into the bloodstream. However, that solvent requires patients to take steroids beforehand, to prevent allergic reactions. It also dissolves ingredients in plastic tubing, making it necessary to use glass vials and special tubing. Furthermore, the castor oil encapsulates the drug so that the target cells can absorb it less readily.
Using the nanoparticle albumin carrier rather than a toxic solvent allows a shorter infusion time, and safer and higher dosages, and elicits a faster response. And it requires no steroids to prevent allergic reaction or special tubing or vials. Significant side effects specific to the paclitaxel (risk to fetus in pregnant women, fertility impairment, nausea, vomiting, diarrhea) still make the treatment less than ideal. However, it represents a significant improvement over current technologies. That’s an important factor considering that breast cancer is the leading cause of death in women between the ages of 20 and 59.
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