Trial Information

Assessment of Cardiovascular Risk Markers in GH Deficient Patients With Nonsecreting Pituitary Adenomas

PROJECT TITLE: Assessment of Cardiovascular Risk in Patients with Growth Hormone Deficiency
Following Transsphenoidal Surgery for Nonsecreting Pituitary Adenomas.

BACKGROUND Recently, an awareness of the risks of hypopituitarism in adults has been raised
by epidemiological studies demonstrating its association with increased mortality, likely
from cardiovascular (CV) causes. In particular, untreated growth hormone deficiency has been
implicated as a possible cause of this increased mortality. A 2004 clinical review of growth
hormone deficiency in adults highlights the plausibility of this argument by citing studies
potentially linking GHD to the following: elevated CRP, LDL and coagulation factor levels,
increased abdominal obesity, increased insulin resistance, increased prevalence of
structural and functional heart disease and increased rates of endothelial cell and large
artery dysfunction. Furthermore, therapy for GH deficiency has been shown to lower total
and LDL cholesterol and reduce visceral fat mass, reduce signs of early atherosclerosis and
perhaps decrease overall risk of myocardial infarction. While these studies suggest that GHD
is an important cardiovascular risk factor, we believe the data are imperfect since some of
the studies chose comparison groups too dissimilar (allowing for the possibility of
unrecognized confounding). Previous studies have assessed cardiovascular risk in patients
with hypopituitarism in comparison to the general population or much younger GH replaced
subjects or GHD patients before and after GH therapy. In contrast, we plan to compare
cardiovascular risk among adult patients rendered growth hormone deficient following surgery
for a non secreting pituitary adenoma versus patients who have undergone the same surgery
but who remain growth hormone sufficient. We plan to test for growth hormone deficiency
using the Arginine/GHRH stimulation test in 80 subjects. We will divide the patients into
two groups: growth hormone deficient and growth hormone sufficient. Once we have recruited
enough patients in each group (thirty), we will compare known CV risk markers and
endothelial function in carefully matched patients from each group. This approach will allow
us to compare similar patients (i.e. all will have undergone surgery, some in each group
will have undergone radiation) whose primary difference will be the GH status. In addition,
from each group we will identify patients with additional pituitary deficiencies in the hope
of comparing patients with either isolated GHD or patients with multiple endocrinopathies to
similar matched controls.

At least two other novel aspects of our study include the use of magnetic resonance
spectroscopy to measure intramyocellular and intrahepatic lipids and venous endothelial cell
biopsy to assess endothelial function. Regarding the first modality, elevated levels of
intramyocellular and intrahepatic lipids have been associated with insulin resistance in
other populations. It is our hypothesis that subtle abnormalities in these lipid stores may
correlate with insulin resistance in patients with apparent occult GH deficiency. With
regard to endothelial function, previous work has linked GHD with endothelial cell
dysfunction but typically through indirect measures including serum markers and arterial
flow mediated dilatation. However, a technique has been recently developed to safely sample
venous endothelial cells which in turn will enable us to assess directly at the level of
endothelial cells, oxidative stress, cell activation and nitric oxide synthesis. It is our
belief that this new method will help confirm the contention that GHD alters the basic
function of endothelial cells.

STUDY DESIGN This study will assess the level of cardiovascular risk in two patient
populations: those patients who are GHD following transsphenoidal surgery for nonsecreting
pituitary adenomas and those patients who are not GHD following similar surgery. The primary
outcome will be serum markers of cardiovascular risk including lipids, CRP, IL6 and
homocysteine.

Experimental Protocol:

Subjects for this study will have all undergone transsphenoidal surgery for a nonsecreting
pituitary adenoma. In addition, there may be some additional subjects, who have also
undergone transsphenoidal surgery for a nonsecreting pituitary adenoma, recruited by word of
mouth from the cohort of patients described above. Only patients who are not receiving GH
therapy will be considered. Of those patients who have received RT, only those at least 5
years from radiotherapy will be recruited in order to lessen the likelihood of a false
positive Arginine/GHRH stimulation test which can occur in the early years post RT.

The remaining respondents will be stratified into two groups based on the presence or
absence of a history of other hypopituitarism: 1) those with > 1 known pituitary hormone
deficiency (other than GH) and who are on replacement for these and 2) those with no known
pituitary hormone deficits. The status of other pituitary hormone replacement therapies will
be verified prior to the arrival of the subjects for further testing. Patients will need to
be on stable doses of replacement therapy for at least 3 months prior to the study visit and
if on hormone replacements they must be on hydrocortisone < 30 mg/day or equivalent and
physiological doses of thyroid and sex steroid replacements. If possible, patients will be
asked to provide copies of their most recent endocrine studies if these were not available
from the chart review to verify the adequacy of their replacement therapy. Any woman known
to be pregnant or any woman of childbearing age with a positive urinary HCG will not be
considered for the study (we will screen all woman of childbearing age at the first visit
prior to initiation of any testing). In addition, any woman actively nursing cannot be
included in the study (we will ask all women of childbearing age at the first visit). We
will recruit equal numbers from these two groups, inviting subjects to our Neuroendocrine
Unit for an initial visit where they will undergo a clinical exam with vital signs,
anthropometric measurements and skin fold thickness assessments. Subjects will also undergo
GH stimulation testing with Arginine/GHRH to identify GH deficient (peak GH < 4 µg/L) and
nonGH de•cient (peak GH > 10 µg/L) groups. Lastly, all subjects will have an endothelial
cell biopsy performed.

Thirty matched pairs of patients from the GHD and GH sufficient groups will be contacted
further for an additional visit to our unit for some or all of the following tests:

- Fasting blood sampling for CV risk markers including CRP, homocysteine, lipoproteins,
IL6 IGFI and IGFBP3 (all subjects, n=30 pairs)

- 75 gm OGTT; Insulin and glucose (all subjects, n=30 pairs)

- DEXA scan to assess body composition and bone density (all subjects, n=30 pairs)

- Ultrasound to assess carotid intimal medial thickness and brachial artery flowmediated
dilatation (subset of subjects, n=10 pairs).

- Magnetic resonance spectroscopy assessment of intramyocellular lipids and intrahepatic
lipids in a subset of each group of the cohort (subset of subjects, n=10 pairs).
Subjects will be studied within 6 months of their initial GH stimulation test.

STUDY DRUGS Subjects will undergo an Arginine/GHRH stimulation test. They will receive Rgene
(Upjohn) a 10% Arginine Hydrochloride solution in water and Geref Diagnostic (Serono).

STUDY SUBJECTS Subjects for the study will include adult patients who have undergone
transsphenoidal pituitary surgery for a nonsecreting pituitary adenoma.

STUDY LOCATION This study will take place out of the Neuroendocrine Unit, Columbia
University.

POTENTIAL RISKS Participation in this study will involve minimal standard risks associated
with blood draws. In addition there is a potential risk from exposure to radiation from DEXA
scans. However, the amount of radiation exposure from DEXA scanning is only one percent of a
chest xray and it is in accordance with federal guidelines for this type of research. Given
the risk posed to a fetus from radiation exposure, pregnant or nursing mothers will be
excluded from the study. To assess for pregnancy we will chec a urine HCG on all women of
childbearing age prior to initiating any testing. In addition, women of childbearing age
will be asked if they actively nursing and if so they will be excluded from the study. Since
the risk to pregnant or nursing mothers is present only at the time of testing, no
additional precautions against pregnancy need to be taken in the days following our testing.
Ultrasound (for IMT and flow mediated dilatation studies) poses minimal risk beyond mild
discomfort from the gel and probe. MRI also poses minimal risk beyond mild discomfort from
the enclosed space and noise of the machine as long as there is no metal within the scanner
room. The subjects will be asked a series of questions by the MRI technicians to ensure that
they are safe to proceed with MRI. In addition, pregnant woman cannot undergo MRI. The risks
of endothelial biopsy are thought to include pain, inflammation, infection and clots. In a
previous study it was found to be safe but patients will be asked to return one week after
the biopsy for evaluation of the site. If any symptoms arise prior to one week follow up
patients will be advised to call or proceed to the emergency room.

The most common adverse reactions from the administration of arginine include nausea,
vomiting, headache, flushing, numbness, local venous irritation. Systemic allergic reaction
is rare but patients with highly allergic tendencies will not be included. Pregnant or
nursing subjects will also be excluded as mentioned above. For GHRH, common side effects
include transient warmth/flushing of face, injection site pain, redness/swelling at site of
injection, nausea, headache, vomiting, strange taste in mouth, paleness, tightness in chest.
A physician will be present throughout the administration of these two drugs.

POTENTIAL BENEFITS The results of the growth hormone stimulation test will be made available
to subjects and their doctors. Therefore, if a subject is found to be growth hormone
deficient, he or she might benefit from growth hormone therapy which has been shown, in some
studies, to improve body composition, cholesterol levels and other factors associated with
an increased risk for cardiovascular disease. A decision to initiate therapy, however should
only occur after a careful discussion between the subject and his or her personal physician
occurs. There may also be some benefit from DEXA scanning as it might identify previously
undiagnosed osteoporosis. This condition has effective treatment options. Lastly,
participation in the study will help further contribute to our understanding of the risk of
heart disease in growth hormone deficient patients.