Nitisinone (NTBC) In Different Age Groups Of Patients With Alkaptonuria

Study procedures are designed to:

1. Develop a method for nitisinone measurement via tandem mass spectrometry (MS/MS).

2. Determine whether differences between adult and children could be erased by employing a
dosage regimen based on m2 of body surface area as opposed to per kg of body weight, as
we have found in a recent study of dichloroacetate

3. Determine optimal dosage for reduction of urinary levels of homogentisic acid and
minimal elevation of plasma levels of tyrosine in the target population of
pre-symptomatic patients.

4. Determine optimal doses of Tyrex to prevent hypertyrosinemia and allow maximal
reduction in homogentisic acid.

Baseline studies will include ophthalmologic examinations, echocardiogram, X-rays of all
joints, MRI of selected joints when financially plausible; history and physical examinations
with emphasis on joints and tendons. Ideally MRI will be repeated at 12 month intervals
thereafter. Ophthalmologic exam, x-rays of the kidneys and prostate, and echocardiogram will
be repeated approximately every 12 months, depending on the age of the subject and the
nitisinone dose. Patients will be seen every 3 months for the first year, then at 6 month
intervals to month 36. The timing of the visits may be altered in response to modifications
of nitisinone and/or Tyrex doses.

Complete or near complete elimination of homogentisic acid excretion will be sought. Optimal
NTBC dosage would be judged to yield plasma concentration of tyrosine less than 1000 mmol/L
with the concomitant use of tyrosine free amino acid supplement. Dosage will be escalated or
reduced dependent on evidence of accumulation of nitisinone and urinary levels of HGA. The
maximum initial dose of nitisinone for adult and adolescent patients will be 0.2/mg/kg/day,
younger patients may require a larger dose; the standard dose in hypertyrosinemia is
1mg/kg/day, which will be tentatively used as the maximum dose for all populations.

Patients will be asked to collect first morning or 12 hour urine collections for
homogentisic acid and p-hydroxyphenyllactic acids and to monitor levels of tyrosine.
Accumulation will be tested for by repeated studies after 3 months of treatment. Trough
levels for nitisinone will be collected prior to and 5-7 days after dose increases and/or at
months 6, 12, 18, 24 and every 12 months.

The SF-36 Health Status Survey, a two page quality of life questionnaire which asks about
ADLs and emotional/social impacts of disease, will be completed by the patient or patient's
parent at baseline and every six months.

At any point during the study if the plasma tyrosine level is greater than 900umol/L the
amount of Tyrex or dietary protein intake may be modified, or the nitisinone dose may be
decreased. Protein Saver blood spot cards, which can be done in the patient's home and
mailed to our lab, will be given to the patients with instructions on blood collection to
check the tyrosine level after 5-7 days of the drug/dietary modifications. These steps—the
dietary modification with diet records if needed, addition or adjustment of Tyrex,
adjustment of the nitisinone dose, and repeat tyrosine analysis—will be repeated as
necessary.

Inclusion Criteria:

1. Diagnosis of alkaptonuria with documented increased excretion of homogentisic acid

2. Willing and able to provide written, signed informed consent, or age appropriate
written assent and written informed consent by a legally authorized representative
after the study has been explained, prior to any research-related procedures.

3. Willing and able to be seen in the UCSD Clinical Center for Research or a satellite
site for the study visits

4. Possession of insurance coverage for standard of care procedures, clearly stated in
the consent forms

Exclusion Criteria:

1. Baseline tyrosine level above 250 mmol/mL

2. Baseline serum creatinine, creatine kinase, or transaminases 2x upper limit of normal

3. Baseline anemia or thrombocytopenia

4. Current participation in another investigational medication trial.

5. Pregnant or lactating women

6. Current keratopathy, contact use or uncontrolled glaucoma

7. History myocardial infarction or arrhythmia

8. History of pulmonary insufficiency

9. Psychiatric illness that may interfere with compliance or communication

10. Current malignancy or hypertension