10/29/2013 6:00:00 AM New therapies offer hope to breast cancer patients
Dr. Hamdy Mohtaseb Kingman Physician
Treatment of breast cancer has been rapidly advancing within the field of oncology. There are different lines of therapy available for this disease, depending on specific cancer subtypes and characteristics.
Breast cancer is a multi-disease entity based on some patient-related as well as tumor-related factors. These factors include the menopausal status of the patient, estrogen and progesterone receptors status, and human epithelial receptor 2 on cancer cells. Some other factors include tumor invasion and grade and type of cancer cell (ductal vs. lobular).
Over the years, treatment of breast cancer consisted of surgery followed by chemotherapy with or without radiation therapy in patients. Targeted therapies are now available against many cancers that represent more effective, less toxic treatment when compared to conventional chemotherapy.
The idea came through the discovery of receptors that are present on cancer cells that promote cancer but are not present nor induce cancer on normal cells. In breast cancer, for example, by targeting certain receptors and pathways through molecular therapies, we are able to specifically achieve direct cancer-cell killing with minimal toxicity in most cases.
One of the most fascinating therapeutic strategies in oncology is the one that targets HER2 receptors. Approximately 20 percent of breast cancers over express HER2, which historically is associated with increased recurrence and an overall worse prognosis compared to HER2 negative breast cancer. However, the discovery of HER2 directed therapy is a paradigm shift that has revolutionized the natural history with increased survival despite a patient having this type of breast cancer. It has abrogated the poor prognosis of this type of breast cancer into a more chronic and favorable disease.
Until recently, there were two anti-HER2 medications, Herceptin and the oral medication Lapatinib. Both are approved for treatment of HER2 positive breast cancer in combination with chemotherapy. We may also use this target therapy, Herceptin, as monotherapy without chemotherapy in patients with limited or asymptomatic advanced breast cancer.
Because HER2 positive breast cancer is historically an unfavorable disease, many patients eventually progress and become resistant to Herceptin and Lapatinib.
Two new generations of anti-HER2 therapies that have proven to be a great benefit in this situation were added this year. In February, the Food and Drug Administration approved a novel anti-HER2 therapy, T-DM1 (Kadcyla), for patients who progress during six months of Herceptin therapy in early (adjuvant) status and those who progressed in the advanced (metastatic) setting.
The approval was based on a landmark EMILIA study of 978 patients who showed significant improvement in disease progression, mortality rate, and overall response rate (44 vs. 31 percent) with less side effects compared to the other HER2 medication Lapatinib with chemotherapy.
That study was followed by another fascinating research project where 808 patients with HER2 metastatic breast cancer showed an improved outcome using another new anti-HER2 therapy, Pertuzumab (Perjeta), in combination with Herceptin and chemotherapy compared to Herceptin or chemotherapy alone. The overall response rate was 80 percent versus 69 percent, which led to the approval of Pertuzumab by the FDA as a new generation of anti-HER2 therapy.
The FDA approved Perjeta on Oct. 2 in combination with other anti-HER2 therapies before surgery in early-stage breast cancer that carries HER2, which could be a remarkable step forward into eradicating this type of breast cancer.
The advantage of treating breast cancer as well as other cancers with these targeted therapies is that the therapies only attack cells that carry those particular receptors, thus preserving or sparing normal tissue from any bad effects.
Chemotherapy, on the other hand, does not differentiate between cancer and normal cells.
There is now a trend of getting away from chemotherapy in treating cancer in general. The reality is we are already at the point where patients with cancer could be treated successfully with these biologic, targeted therapies rather than the more toxic modalities. We are already seeing steps in that direction in lung, kidney and prostate cancers, as well as in leukemia and lymphoma and, in the near future, breast cancer.
If you have any questions on this topic, please contact our offices either in Kingman (928) 681-1234 or Fort Mohave (928) 770-4560. We will be happy to address your questions promptly.