I am hearing alot about Herceptin lately. What is it and what does it do?
Angela DeMichele, M.D., MSCE, Assistant Professor of Medicine and Epidemiology at the University of Pennsylvania and Senior Scholar in the Center for Clinical Epidemiology and Biostatistics responds:
In certain types of breast cancer there is an overabundance of a certain protein called "Her2/neu" on the surface of the cells. Her2/neu is a growth factor receptor that binds growth factors which are molecules that circulate in the blood. When the growth factor binds with the growth factor receptor it stimulates the cell to divide. Scientists have developed Herceptin to compete against the growth factor and bind with Her2, blocking the effect of the growth factor on the receptor . When Herceptin is binding Her2 the cell is unable to divide. This interferes with the cells' biological processes, which eventually causes the breast cancer cell to die.
Herceptin has been demonstrated to have anti-cancer activity in patients with the type of metastatic breast cancer that overexpresses Her2. A more recent study published in abstract form at the 1998 annual meeting of the American Society of Clinical Oncology reported on the efficacy of Herceptin when combined with chemotherapy. 469 patients were randomized to four arms:
- Taxol alone
- Adriamycin and Cyclophosphamide
- Herceptin with Taxol
- Herceptin with Adriamycin and Cyclophosphamide.
Patients receiving Herceptin had significantly longer time to progression and better response rates. However, when the Herceptin was given with the Adriamycin and Cyclophosphamide regimen, patients developed a high rate of heart problems. The combination of Herceptin and Taxol was well tolerated, and became a standard approach in this setting.
Herceptin has also been studied with other chemotherapy drugs in metastatic breast cancer (like Navelbine and Gemcitabine) and appears to also boost the effectiveness of these drugs in shrinking the tumors.
More recently, several studies have now shown that giving Herceptin at the earliest stages of breast cancer, along with or following adjuvant chemotherapy, can reduce the chance of the breast cancer returning by almost 50%. Three studies have examined this issue. Two gave the Herceptin along with adjuvant Taxol, then following the chemotherapy for a year. Another study gave the Herceptin only after the completion of the chemotherapy for either one or two years. While there are still unanswered questions about the ideal way to give the Herceptin, most oncologists agree that it should be used in the adjuvant treatment setting when the initial tumor is strongly positive for Her2/neu protein. Most patients now received a year of Herceptin (given every three weeks) as part of their adjuvant therapy. Heart monitoring is important during treatment with Herceptin, and should be done regularly for all patients who are taking the drug. This can typically be done with a MUGA scan, done at regular intervals. Further studies are underway to develop the best approach and optimal duration of treatment. Thank you for your question and your interest.