Danazol for Genetic Bone Marrow and Lung Disorders

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disorder characterized
by pancytopenia and a hypocellular bone marrow. Telomeres were reported to be short in up to
one-third of patients with SAA.Initially this occurrence was presumed to be secondary to
hematopoietic stress. However, the discovery of loss-of-function mutations in genes of the
telomerase complex (TERC, TERT) established a genetic etiology for telomere attrition in some
patients with marrow failure who did not have the stigmata associated to an inherited bone
marrow failure syndrome. These findings implicated telomerase dysfunction in failed
hematopoiesis. In family members of probands with SAA, telomerase mutations have been
observed which were associated to varying degrees of cytopenias, idiopathic pulmonary
fibrosis (IPF) and/or cirrhosis.

Telomere length has been associated with human cancer. Telomere attrition has been implicated
in a variety of solid organ malignancies including esophageal and colon adenocarcinoma. In a
longitudinal population based study, shorter telomere length associated to a higher cancer
mortality risk overtime. It is plausible that a shorter telomere length is not just a
biomarker associated to development of cancer, but involved in its pathogenesis. Ample
experimental data supports an important role of critically short telomere length in genomic
instability. Furthermore, our laboratory data (unpublished) shows that similar chromosome
instability occurs in bone marrow cells of mutant patients, confirming the experimental data.
Thus, a common molecular mechanism appears to underlie risk for cancer and a range of
clinical entities.

In vitro studies suggest that telomere length could, in theory, be modulated with sex
hormones.15 Exposure of normal peripheral blood lymphocytes and human bone marrow derived
CD34+ cells to androgens increased telomerase activity in vitro and androgens increased low
baseline telomerase activity in individuals carrying a loss-of-function TERT mutation to
normal levels. In retrospect, the beneficial effects of sex hormones on telomerase activity
may be the mechanism by which SAA patients treated over 40 years ago with male hormones
showed hematologic improvement in some cases.

In recent years we have seen patients referred to our clinic with varying degree of
cytopenia(s) who had significant family history for cytopenia(s), IPF and/or cirrhosis. We
have identified very short telomeres in these patients and in some mutations in TERC and
TERT. We hypothesize that male hormone therapy might modulate telomere attrition in vivo and
ameliorate progression or reverse the clinical consequences of accelerated telomere
attrition. Therefore, we propose male hormone therapy in patients with cytopenia(s) and/or
IPF who show evidence of telomere dysfunction by a short age adjusted telomere length
associated to telomerase gene mutations. The primary biologic endpoint will be delay of
telomere attrition over time compared to known rates of telomere erosion in normal
individuals and in those who carry mutation in the telomerase genes. The main clinical
endpoint will be tolerability of oral danazol over two years. Secondary endpoints will be
improvement in blood counts and/or pulmonary function. The small sample size, lack of control
groups, and variable clinical course among those with marrow failure and IPF, will not allow
for definitive assessment of clinical benefit. Nevertheless, we believe this protocol will
provide insight into the possible effects of androgen therapy on telomere attrition in humans
and of possible clinical benefit in telomere related disorders, and serve as hypothesis
generating for further larger controlled studies.

- INCLUSION CRITERIA:

1. Short age-adjusted telomere length in the first percentile and/or a mutation in
telomerase genes

2. One or more of the following cytopenia(s).

- Anemia

1. Symptomatic anemia with a hemoglobin < 9.5 g/dL or red cell transfusion
requirements > 2 units/month for at least 2 months

2. Reticulocyte count < 60,000 /microL

- Thrombocytopenia

1. Platelet count < 30,000 /microL or < 50,000 /microL associated with bleeding

2. Decreased megakaryocytic precursors in the bone marrow

- Neutropenia

1. Absolute neutrophil count < 1,000 /microL

OR

3. Idiopathic pulmonary fibrosis diagnosed by either a lung biopsy of high
resolution computed tomography scan of the chest according to guidelines from the
American Thoracic Society and European Respiratory Society

4. Age greater than or equal to 2 years

5. Weight > 12 kg

EXCLUSION CRITERIA:

1. Moribund status or concurrent hepatic, renal, cardiac, neurologic,
pulmonary, infectious, or metabolic disease of such severity that it would
preclude the patient s ability to tolerate protocol therapy, or that death
within 30 days is likely

2. Potential subjects with cancer who are on active chemotherapeutic treatment

3. Current pregnancy, or unwillingness to avoid pregnancy if of childbearing
potential

4. Not able to understand the investigational nature of the study or give
informed consent or does not have a legally authorized representative or
surrogate that can provide informed consent.