Low-Dose Danazol for the Treatment of Telomere Related Diseases

Telomere disease is caused by accelerated telomere attrition and results in multi-organ
dysfunction. Telomeres are nucleotide repeats of non-coding DNA at the end of the chromosomes
which function as protective caps to prevent erosion of genomic DNA during cell division and
to protect chromosomes from recognition as single stranded DNA. Telomeric DNA is elongated by
the telomerase complex, which is comprised of a reverse transcriptase catalytic subunit
(encoded by TERT), an RNA template (encoded by TERC) and associated proteins. Telomerase
activity is crucial in maintaining telomere length in cells with a high proliferative
capacity, such as hematopoietic stem cells (HSCs) and lymphocytes. Presentation of
telomeropathies can vary from severe aplastic anemia (SAA) and dyskeratosis congenital (DKC)
early in childhood, to pulmonary or hepatic fibrosis later in life. There is no standard of
care for the treatment of telomere disease.

Considerable evidence suggests that sex hormones regulate telomerase. Calado et al.
demonstrated that human lymphocytes and CD34+ hematopoietic cells up regulate both TERT gene
expression and telomerase enzymatic activity in response to androgens in vitro. A recent
observational cohort study demonstrated hematologic response in 14 of 16 pediatric patients
with DKC treated with androgens. In a prospective trial from our Branch, Townsley et al
demonstrated that patients with telomere diseases who were treated with the synthetic sex
hormone danazol showed telomere elongation, and hematologic response were seen in 79% of
patients after only three months of treatment. This study used the highest dose of danazol,
800 mg daily, and known adverse effects, such as elevated liver enzyme levels and muscle
cramps, occurred in 41% and 33% of patients, respectively. Overall the treatment was well
tolerated, but some patients did require dose reduction. After 27 patients were enrolled, the
study was halted early, because telomere attrition was reduced in all 12 patients who could
be evaluated for the primary endpoint. Because of the limited power, we were unable to draw
definitive conclusions regarding further clinical effect of danazol but stabilization or
improvement was observed in a few cases in other organ function, measured by DLCO for
pulmonary fibrosis and Fibroscan for cirrhosis.

We now propose a phase II study designed to determine the efficacy of low dose danazol in
decreasing the rate of telomere attrition in subjects with a short age-adjusted telomere
length. The secondary aim is to determine the clinical effect of this therapy in conditions
that are related to short telomeres, to include cytopenia(s), pulmonary fibrosis, and/or
hepatic fibrosis.

- INCLUSION CRITERIA:

1. Age-adjusted telomere length less than or equal to the first percentile

2. A mutation in telomere maintenance genes (TERT, TERC, DKC1, TINF2, NHP2, NOP10,
WRAP53, TERF2, PARN, RTEL1, ACD, CTC1, USB1)

3. Age greater than or equal to 3 years

4. Weight greater than or equal to 12 Kg

AND

5. At least one of the following criteria:

1. Anemia with a hemoglobin less than or equal to 10 g/dL without red blood
cell transfusion

2. Thrombocytopenia with a platelet count less than or equal to
50,000/microliter without transfusion

3. Neutropenia with an absolute neutrophil count less than or equal to 1,000/
microliter

OR

Pulmonary fibrosis diagnosed by either a lung biopsy or computed tomography scan
of the chest according to guidelines from the American Thoracic Society and
European Respiratory Society.

OR

6. Hepatic fibrosis diagnosed by Transient Elastography by Fibroscan value greater
than 10 kpa or US evidence of cirrhotic liver or splenomegaly, or transjugular
liver biopsy demonstrating fibrosis.

EXCLUSION CRITERIA:

1. Patients on androgen hormones to include testosterone or high dose estrogen (estradiol
0.5 mg/day or greater) for the12 months prior to enrollment

2. Patients with active thrombosis or thromboembolic disease and history of such events,
undiagnosed abnormal genital bleeding, porphyria, androgendependent tumor, or
prostatic hypertrophy

3. Patients with pulmonary fibrosis who are receiving anti-fibrotic drug treatment, such
as pirfenidone or nintedanib and who have not undergone a 1 month washout period

4. Patients with active hepatitis B or C

5. Patients who have received a bone marrow transplant

6. Patient with other hereditary bone marrow failure syndromes such as Fanconi anemia or
Diamond Blackfan anemia

7. Patients with infections not adequately responding to appropriate therapy

8. Current pregnancy, or unwillingness to take oral contraceptives or use the barrier
methods of birth control or practice abstinence to refrain from pregnancy if of
childbearing potential during the course of the study

9. Lactating women, due to the potentially harmful effects on the nursing child

10. Patients with cancer who are actively receiving systemic chemotherapeutic treatment or
who take drugs with hematological effects

11. Patients with decompensated liver disease to include persistent ascites,
encephalopathy, variceal hemorrhage, or MELD score of 10 or greater

12. Inability to understand the investigational nature of the study or to give informed
consent or without a legally authorized representative or surrogate that can provide
informed consent

13. Inability to swallow a capsule