Good News for Metastatic Breast Cancer Patients

By Erica L. Mayer, MD, MPH

There has been remarkable recent progress in identifying effective treatments for patients with metastatic breast cancer – that is, cancer that has spread beyond the breast and underarm lymph nodes to other parts of the body.

Many Dana-Farber patients have contributed to current treatment advances through participation in clinical trials. Consequently, we’ve seen new chemotherapies introduced, such as eribulin (Halaven), and new types of biological therapy, including everolimus (Afinitor) and pertuzumab (Perjeta), approved by the FDA in the past year.

We also have a better understanding of the subtypes of breast cancer, and based on this knowledge are conducting multiple clinical trials to study the effect of new targeted drugs, particularly in patients with metastatic disease.

Breast cancer is actually composed of three subtypes, listed below with the percent of women affected.

• Hormone-receptor positive (HR+), 65-75 percent.  Fueled by estrogen and/or progesterone.

Many patients with HR+ breast cancer respond well to hormonal medications such as tamoxifen, aromatase inhibitors, or fulvestrant (Faslodex) that prevent estrogen from stimulating the cancer cell. However, cancer is a very smart enemy, and often, it figures out how to resist the drug.

That is why we have been working to find medications that overcome this resistance. One way is to simultaneously interrupt growth factor pathways, going after other important cancer cell targets at the same time with new medications. One such drug, everolimus, was recently FDA- approved to be used in combination with a hormonal medication for metastatic HR+ cancer. Several other inhibitors are also in clinical trials.

• HER2-positive, 20 percent.  Dependent on HER2, a protein found on the surface of the cancer cell.

For women with HER2 positive breast cancer, targeting the cancer cell with a medicine like trastuzumab (Herceptin) or lapatinib (Tykerb) is a standard of care. However, 2012 has brought two new exciting drugs for HER2 positive breast cancer. One new agent is pertuzumab, an antibody treatment which was recently approved to be used with trastuzumab and chemotherapy for women newly diagnosed with metastatic HER2 positive breast cancer.

Another exciting, effective, and well-tolerated new drug is TDM1, a “smart bomb” type of medication which is expected to be approved for metastatic HER2 positive breast cancer in early 2013.

• Triple negative, 15 percent. Does not contain estrogen, progesterone, or HER2 receptors.

Hormonal or HER2 therapies are not effective against triple negative breast cancer (TNBC). Chemotherapy is quite active, and we have several new types in clinical trials which may be good choices for TNBC. One major discovery is that TNBC is made up of 6 separate subgroups with unique genetic profiles.  Finding new targets and medicines for the subgroups of TNBC is an area of very active research, and we have many ongoing trials for patients with metastatic TNBC.

I encourage all breast cancer patients  to talk with their providers about participating in clinical trials. Being on a trial has many benefits, including the chance to work with a larger treatment team, access to cutting-edge treatments, and the ability to help future patients.

Erica Mayer, MD, MPH, is a breast cancer clinician and researcher in the Breast Cancer Treatment Center at Dana-Farber, director of clinical research at Dana-Farber/Brigham and Women’s Cancer Center at Brigham and Women’s Faulkner Hospital, and assistant professor in Medicine at Harvard Medical School. She researches new treatments for breast cancer and is active in breast cancer education.  

See Dr. Mayer’s presentation on this topic at a recent Dana-Farber forum for metastatic breast cancer patients.