PDUFA: Kadcyla, Immunogen – Metastasized Breast Cancer

Metastasized breast cancer now has a new therapy on the market, though it remains to be seen whether noticeably dangerous side effects may prevent widespread use.

Trastuzumab emtansine (T-DM1) or Kadcyla, produced by Immunogen [Nasdaq: IMGN], is an antibody-drug conjugate that targets the HER2 protein. This is the protein involved in normal cell growth and when observed in an increased amount, contributes to cancer cell survival. Approximately 20% of all breast cancers are HER2-positive, a particularly aggressive form of the disease associated with increased early-stage mortality and metastases. The FDA approved the drug in late February, but slapped on it a ‘black box’ warning due to links to liver toxicity, heart toxicity, and death.

Immunogen is the originator and current holder of Kadcyla. The company  conceived of the idea of attaching the Company’s DM1 maytansinoid cell-killing agent to Genentech’s trastuzumab antibody to achieve a highly effective, HER2-targeted anticancer agent. In 2000, Genentech licensed from ImmunoGen exclusive rights to use the Company’s maytansinoid TAP technology to develop anticancer products targeting HER2.

In 2006, Genentech advanced the compound that became known as Kadcyla into clinical testing. Genentech has implemented a broad Kadcyla clinical development program that has continued to expand subsequent to Genentech’s acquisition by Roche.

“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,” Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said.

Trials for Kadcyla showed promise in the summer of the 2012, demonstrating an extremely successful rate of improvement. However, trials also demonstrated a low rate of adverse events for T-DM1 relative to systemic chemotherapies. The results of the study were published by the Journal of Clinical Oncology. Involved in that study very early was Javier Cortes, MD of the Vall d’Hebron University Hospital and Institute of Oncology, Barcelona, Spain. Dr. Cortes was very impressed with the nearly 6-month improvement in survival.

“I do not remember any paper in metastatic breast cancer with an improvement of 6 months. T-DM1 is clearly better than previous drugs for survival. This will benefit thousands of women.”

He also said that the cardiac safety data suggest that T-DM1 may be a favorablei option for patients who cannot receive trastuzumab due to cardiac problems.

In addition to trastuzumab, lapatinib, and pertuzumab, T-DM1 is the fourth anti-HER2 drug to be approved by the FDA. This treatment adds another option for physicians who treat breast cancer, which is the second leading cause of cancer-related death among women, according to the FDA.

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