Clinical management of locally advanced breast cancer remains challenging as patients have a high risk for relapse, especially those patients whose tumors over-express the HER-2/neu (HER2+) oncogenic protein and have limited expression of estrogen receptors (ER-). The standard treatment strategy is neoadjuvant therapy (paclitaxel in combination with trastuzumab, a monoclonal antibody specific for HER2), followed by surgery. However, this approach achieves a complete response in only a minority of patients.
This study will add the mushroom product polysaccharide Krestin (PSK), a nontoxic immunomodulator, to standard neoadjuvant therapy as a new therapeutic approach. PSK has long been used in Asia as an immune potentiating and anti-cancer drug. Our preliminary experiments in animal models have shown that PSK by itself augments immunity and inhibits tumor growth. We hypothesize that the addition of PSK to standard therapy with paclitaxel and trastuzumab will augment anti-tumor immunity and result in improved responses and overall survival.