Octreotide in the Management of Hormone-Refractory Prostate Cancer

Abstract

Patients with advanced or metastatic prostate cancer (PC), a partially hormone-resistant disease, will require some form of hormonal manipulations or some new therapeutic modalities. Octreotide, as somatostatin (SST) analogs, has been found to inhibit the growth of experimental PCs via several mechanisms, as indirect antihormonal and direct antimitogenic actions, mainly due to inhibition of SST receptor subtypes (SSTR-1–5). Sporadic clinical trials with octreotide (alone or with a complete antiandrogen blockade) treatment of patients with advanced stage D2 PC demonstrated promising results. Unfortunately, at present these clinical trials have some disadvantages and leave some uncertainty with regard to the trial design, the SSTR subtype determination and tumor localization with SSTR scintigraphy before the start of a selective SST analog, and finally the randomization in groups according to hormone resistance, dosage regimen and route of administration.

Somatostatin, cortistatin and their receptors in tumours

“…Pituitary adenomas and well-differentiated endocrine tumours (so called benign or malignant particularly in hormone independent prostatic carcinomas at advanced stages (Vainas et al 2001, Plonowski et al 1999. Sst subtypes have also been detected in meningiomas and gliomas, in soft tissues sarcomas and in malignant melanomas; this distribution correlated with either scintigraphic imaging or in vitro tests on SS analogue response (Reubi et al 1987, Doutur et al 1998, Friedberg et al 1999, Lum et al 2001.…”

Castration-Resistant Prostate Cancer: Targeted Therapies

“…Patients with advanced or metastatic PCa having a partially hormone-resistant disease could undergo a specific biological evaluation of the tumor and could require some new therapeutic modalities such as, in some cases, octreotide [73,74]. Initially responsive to androgen ablation, many men eventually become castration resistant, develop skeletal metastases, and are palliatively treated with docetaxel-based chemotherapy, radiation therapy, bisphosphonates, and the best supportive care.…”

New Agonist- and Antagonist-Based Treatment Approaches for Advanced Prostate Cancer

“…63 Octreotide has also been shown to inhibit proliferation of a prostate cancer cell line by blocking the somatostatin receptor subtypes 1 -5 and by indirect antihormone action or direct inhibition of cell division. 64 In 2009, octreotide completed phase I and II clinical trials in the USA where it was found to have some therapeutic effect in the treatment of hormone-independent prostate cancer. 65 Octreotide has been approved to treat tumours that are positive for somatostatin receptor 2.…”