Phase II study of RC-160 (vapreotide), an octapeptide analogue of somatostatin, in the treatment of metastatic breast cancer

Br J Cancer. 1999 Mar;79(9-10):1413-8. doi: 10.1038/sj.bjc.6690226.


RC-160 (octastatin/vapreotide) is a potent octapeptide analogue of somatostatin with growth inhibitory activity in experimental tumours in vitro and in vivo, including breast cancer. We evaluated the efficacy and tolerability of high-dose RC-160, 3 mg day(-1) on week 1 increased to 4.5 mg day(-1) for weeks 2-4 and subsequently 6 mg day(-1) until the end of treatment, administered by continuous subcutaneous infusion in the management of 14 women with previously treated metastatic breast cancer. The age range was 37-80 years (median 58.5 years) and performance status 0-2. The treatment was well tolerated with no dose reductions being required. No grade 3 or 4 toxicities were seen. Abscess formation developed at the infusion site in eight patients and erythema and discomfort was seen in a further three patients. A significant reduction in IGF-I levels occurred by day 7 and was maintained throughout the treatment. The lowest dose of RC-160 produced the maximal IGF-I response. Although there was no reduction in prolactin levels in patients whose baseline levels were normal, elevated prolactin levels found in three patients fell to within the normal range 7 days after commencing RC-160 treatment. A small but significant rise in fasting blood glucose levels was also recorded, the highest level on treatment being 7.6 mmol l(-1). No objective tumour responses were observed, all patients showing disease progression within 3 months of commencing treatment. These findings demonstrate that high-dose RC-160, administered as a continuous subcutaneous infusion, can reduce serum levels of the breast growth factors IGF-I and prolactin but is ineffective in the management of metastatic breast cancer. Encouraging preclinical anti-tumour activity and the favourable toxicity profile in patients suggest the merit of future studies combining RC-160 with anti-oestrogen, cytotoxic and anti-angiogenic agents.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase II
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / administration & dosage*
  • Antineoplastic Agents / adverse effects
  • Breast Neoplasms / blood
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Disease Progression
  • Female
  • Humans
  • Insulin-Like Growth Factor I / metabolism
  • Middle Aged
  • Neoplasm Staging
  • Prolactin / blood
  • Somatostatin / administration & dosage
  • Somatostatin / adverse effects
  • Somatostatin / analogs & derivatives*


  • Antineoplastic Agents
  • vapreotide
  • Somatostatin
  • Insulin-Like Growth Factor I
  • Prolactin