An antidepressant drug that was approved by the FDA in 1959 is being put to new and promising use to fight hard-to-treat breast cancers.

The antidepressant, imipramine, was approved to treat cancer patients facing severe depression. However, Dr. Ratna Vadlamudi, co-director of the Mays Cancer Center’s Progression and Development Program, noted that researchers believed the drug may have anticancer properties.

Dr. Vadlamudi’s laboratory has been instrumental in training future scientists, graduate students, and postdoctoral fellows. The doctor advised his associates that the National Cancer Institute considers it a priority to investigate any drug that has been FDA-approved for a disease if it appears to have potential as a cancer treatment (a repurposed drug).

Dr. Vadlamudi gave the youngest member of the team a list of FDA-approved drugs. After studying the list and subsequent discussions, the cancer team agreed to go forward with imipramine.

Further research at UT Health in San Antonio and the Long School of Medicine provided evidence of imipramine’s anticancer potential. The findings led to a clinical trial conducted at the Mays Cancer Center which enrolled fifteen breast cancer patients.

The trial results confirmed that imipramine inhibits both estrogen receptor-positive breast cancer and triple-negative breast cancer in human and mouse tumors.

The journal Cancer Letters published the trial results:

·      Imipramine disrupts the growth of estrogen receptor-positive breast cancers, and

·      Similar to normal cells, DNA repair also exists in cancer cells which develop increased DNA repair by over-expression of DNA proteins. Imipramine interferes with the repair of DNA in cancer cells, thus restricting triple negative-breast cancer’s survival.

A second clinical trial led by Dr. Virginia Kaklamani, who leads the Mays Center’s Program for Breast Cancer, administered imipramine to women who were newly diagnosed and awaiting surgery.

Dr. Kaklamani explained that there is usually a small window of several weeks between diagnosis and surgery. This gives the cancer team time to administer the drug and then monitor its effect on the cancer tissue.

A biopsy is obtained during diagnosis and again during surgery. The care team then determines whether there is any change in the cancer resulting from the imipramine treatment.

Dr. Kaklamani explained that by observing the fifteen patients treated with the drug, they found that it could decrease tumor growth.

The Mays Cancer Center funded the study which showed imipramine to be an active drug for the treatment of breast cancer.

As Dr. Vadlamudi points out, if a drug has already been FDA-approved for a specific disease and is later discovered to fight cancer cells, it can be repurposed and made available for use in clinics.

One of the goals of the National Cancer Institute is to repurpose FDA-approved drugs for cancer giving hope to women worldwide who have been diagnosed with previously untreatable breast cancers.