Kadcyla (ado-trastuzumab emtansine), a new medication for the treatment of HER2-positive, metastatic breast cancer, has been approved by the Food and Drug Administration (FDA), USA.

Metastatic, also known as late-stage, means the cancer has spread to other parts of the body.

HER2, a protein which drives normal cell growth, is found in larger quantities in several kinds of cancer cells (HER2-positive), including a number of breast cancers. The HER2 protein contributes to the growth and survival of cancer cells in patients with HER2-positive breast cancer.

HER2 stands for Human Epidermal growth factor Receptor 2.

Kadcyla is to be used for patients who have already been treated with other anti-HER2 therapies – trastuzumab, as well as taxanes, a class of chemotherapy medications widely used for breast cancer treatment.

Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said:

“Kadcyla is trastuzumab connected to a drug called DM1 that interferes with cancer cell growth. Kadcyla delivers the drug to the cancer site to shrink the tumor, slow disease progression and prolong survival. It is the fourth approved drug that targets the HER2 protein.”

Kadcyla, which was referred to as T-DM1 during the research phase, was reviewed under the FDA’s priority review program, which allows submissions to go through an accelerated 6-month process. The program is designed for medications that are shown to be safe and effective when no other suitable therapy exists, or can offer considerable improvements compared to products already on the market.

There are currently three other FDA-approved medications for the treatment of HER2-positive breast cancer: trastuzumab (approved 1998), lapatinib (approved 2007) and Pertuzumab (approved 2012).

FDA experts evaluated Kadcyla’s safety and efficacy by examining data from The EMILIA study involving 991 patients who were randomly assigned into two groups:

  • The Kadcyla group
  • The lapatinib plus capecitabine group (capecitabine is also a chemotherapy drug)

The patients continued receiving treatment until either the cancer progressed or the side effects from the medication(s) became too much to bear. The study had two co-primary endpoints:

  • Progression-free survival, meaning how long it took before the cancer started progressing again.
  • Overall survival (how long patients lived for).

The trial results showed:

  • Those in the Kadcyla group survived progression-free for 9.6 months
  • Patients in the lapatinib plus capecitabine group survived 6.4 months progression-free
  • Patients in the Kadcyla group had a median overall survival of 30.9 months
  • In the lapatinib plus capecitabine group, median overall survival was 25.1 months

The FDA says that Kadcyla will have a Boxed Warning alerting doctors and patients that the medication can cause heart toxicity, liver toxicity, and death. It can also cause serious and life-threatening birth defects. A woman’s pregnancy status should be checked before starting her on Kadcyla.

Side effects reported in the Kadcyla clinical study included joint pain, muscle pain, thrombocytopenia (low platelet levels in the blood), raised levels of liver enzymes, constipation, headache, fatigue and nausea.

According to the National Cancer Institute, breast cancer is the second leading cause of cancer-related deaths among females in the USA. In 2013, an estimated 232,340 women will be diagnosed with breast cancer and 39,620 will die from it. The World Health Organization says that breast cancer is the most common cancer among women worldwide.

Nearly 1 in every 5 breast cancers has higher levels of HER2 protein.

Kadcyla is marketed by Genentech Inc., California. (a member of the Roche Group). Genentech also markets trastuzumab and Pertuzumab. Lapatinib is marketed by GSK (GlaxoSmithkline).

Hal Barron, M.D., chief medical officer and head, Global Product Development, Genentech, said:

“Kadcyla is an antibody-drug conjugate representing a completely new way to treat HER2-positive metastatic breast cancer, and it helped people in the EMILIA study live nearly six months longer. We currently have more than 25 antibody-drug conjugates in our pipeline and hope this promising approach will help us deliver more medicines to fight other cancers in the future.”

Genentech says that Kadcyla will be available in the USA within the next two weeks. The company plans to start patient assistance programs for patients taking Kadcyla through Genentech Access Solutions, which helps people who cannot afford to pay for the medication, such as those with no health insurance, or have reached the lifetime limit set by their insurance company.

Genentech says that it has been researching the HER2 pathway for more than three decades. The company says “The development of HER2-targeted therapies represents one of the first successful examples of personalized healthcare”.

Roche, a major player in the cancer drugs market, is desperately seeking a replacement for its third best-selling drug Herceptin (trastuzumab), which will face competition from “biosimilar” generic makers in 2015.

Written by Christian Nordqvist