COMBINATION THERAPY                                                      

Although targeted therapies are unlikely to completely replace chemotherapies, increasingly complex regimens incorporating targeted therapies alongside chemotherapies or hormonal therapies will become commonplace as treatment regimens become better tailored to individual patient diseases.

Approximately 50% of breast cancer patients are estrogen receptor (ER) positive. These tumors are stimulated and partially dependent upon estrogen. Tamoxifen, an inhibitor of estrogen action, can be effective in breast cancer patients that are ER positive however their tumors often become resistant to hormonal therapies. A smaller number (~30%) of breast cancer patients have tumors that are stimulated by the HER2/neu pathway. Of these 30%, only one-third are successfully treated with Herceptin^® which inhibits the HER2/neu pathway.

However, 70 to 90% of breast and ovarian cancers are prolactin receptor (PRLR) positive and these tumors are stimulated by prolactin (PRL). More importantly, the PRL pathway in tumors can cross-activate HER2/neu and ER, which is probably responsible for the resistance to Herceptin and/or Tamoxifen therapy. Prolanta therefore offers a novel candidate for breast cancer therapy either as a stand-alone agent or as part of a combinational approach for a larger proportion of patients.

Effects of Prolanta and Herceptin on the Growth of T-47D

Additive Effects of Prolanta and Tamoxifen

Preclinical data illustrate that combining Prolanta therapy with either Herceptin or Tamoxifen results in an even more effective breast cancer treatment than either product alone. patients.

Preclinical investigations are currently underway to determine if Prolactin is synergistic with chemotherapeutic agents commonly used to treat ovarian cancer.