Pasireotide (SOM230) With or Without Everolimus in Treating Patients With Hormone Resistant, Chemotherapy Naive Prostate Cancer

Prostate cancer cells typically have neuroendocrine (NE) differentiation features after they become resistant to hormonal therapy. Somatostatin (SST - a peptide hormone) receptors (SSTR) are usually expressed in a high level in these advanced prostate cancer cells. When SSTR is activated pharmacologically by drugs similar to SST, prostate cancer cell growth is inhibited. SOM230 is a new agent which can activate SSTR and block other key survival molecules/pathways such as phosphatidylinositol 3-kinases (PI3K), mitogen-activated protein (MAP) kinases (MAPK) signaling pathways. Thus SOM230 itself has anticancer activity for prostate cancer.

It is also well known that hormonal refractory prostate cancer can grow in an environment of very low male hormone level because of the activation of several non-androgen receptor survival pathways. One key survival pathway is mediated by an important molecule called mammalian target of rapamycin (mTOR). Drugs, such as Everolimus, have anticancer activity in prostate cancer pre-clinically, but do not sustain its activity. The reason was that cancer cells can up-regulate other survival pathways such as PI3K, MAPK, thus bypass mTOR.

It is hypothesized that SOM230 not only have anti-tumor effect in prostate cancer directly, but also can block the up-regulated (feed-back loop), alternative PI3K or MAPK survival pathways induced by mTOR inhibitors.

The goal of this study is to develop a new well tolerated therapy that can be offered to prostate cancer patients prior to receiving chemotherapy.