The Effect of Monoclonal Vascular Endothelial Growth Factor (VEGF) Antibody (Bevacizumab) on Pituitary Function

The purpose of this research is to determine whether the drug, Bevacizumab (a monoclonal anti VEGF-A antibody), which is approved to treat patients with metastatic colon cancer induces hyperprolactinemia (increased prolactin secretion) in humans with intact pituitary function. Past studies have shown Bevacizumab to shrink tumor size and also increase prolactin levels. The mechanism of the hyperprolactinemia might be inhibition of pituitary portal vein transport, suggesting that Bevacizumab induces prolactin secretion from normal lactotrophs in the pituitary gland.

Patients who have been treated with Bevacizumab for at least one month will be recruited to participate.

The subjects who are being treated with Bevacizumab by Dr. Stephen Wolin (a sub-investigator) will be screened by him for study eligibility. Dr. Wolin will approach eligible patients with all the information and background of the study and see if they have an interest in being consented.

If consented, there will be 2 blood draws for the research that is not part of their standard care in which 10 ml of blood is collected and prolactin, growth hormone, IGF-I, TSH, thyroxine, ACTH, and cortisol will be measured. One 5ml blood draw will occur before the administration of Bevacizumab and the second 5 ml blood draw will occur after the administration of the Bevacizumab. The investigators will then review the laboratory results. The blood tests are of the hormones of the pituitary gland to test pituitary function and see if there are any abnormalities with the secretions of the gland. Pituitary function abnormalities and hyperprolactinemia are diagnosed by looking at hormone levels in the blood and comparing them to the normal reference ranges.

This study will only involve 10 subjects and will be conducted entirely at Cedars-Sinai Medical Center.