Transcript Figure 1 - PreKUlab

Experience with long term use
of LNAA in treatment of PKU
Reuben Matalon1, Kimberlee Michals-Matalon2, Gita
Bhatia1, James Grady1, Stephen Tyring3.
1The
University of Texas Medical Branch, Galveston,
Texas77555. 2University of Houston, Texas 77204,
3The University of Texas Health Science Center,
Houston, Texas 77030,
Abstract
Previous loading of Short term studies with Large Neutral Amino Acids (LNAA) in
patients with PKU resulted in decrease of blood phenylalanine (Phe) levels. The
long term safety, efficacy and acceptability of LNAA tablets (NeoPhe) have not
been evaluated. In this study, four patients, three female and one male, ages 25
to 38 years, were given NeoPhe tablets, 0.5gm/kg/day in three divided doses to
be taken with meals. The patients were not on medical foods, for more than 10
years previously. Their blood Phe prior to taking NeoPhe had a mean value of
1507 mmol/L. Blood Phe were determined two weeks after entering the study
and once a month for a period of 12 months. The mean blood Phe level declined
for each of the subjects during the study period: 642 mmol/L, 707 mmol/L, 899
mmol/L and 869 mmol/L. All patients reached levels within the NIH consensus
report recommendation. Patients were monitored for weight incase, LNAA was
used for protein synthesis. None of the patients gained or lost any weight beyond
minor fluctuation of +/- 0.2 kg. The acceptability of the pills was monitored with
review on every visit and there were no complains regarding the number of pills
or of abdominal discomfort, nausea or changes in bowel habits. All patients
asked to continue taking NeoPhe tablets because they were happy with their
blood Phe levels and indicated they felt “more focused” at work. Future studies
should include larger number of patients and neuropsychological tests need to be
added.
Introduction
•
Dietary treatment of phenylketonuria (PKU) has been the corner stone for
controlling blood phenylalanine (Phe) concentrations in PKU. Such control has
become difficult when blood Phe concentrations need to be controlled for the life
of the patient. Methods to improve dietary control include addition of
tetrahydrobiopterin (BH4) to the management and reformulation of formulas to
make them more palatable. In order to decrease entry of Phe to the brain of
patients with PKU, large neutral amino acids (LNAA) have been added to
compete with the transporter of Phe. In 1987 Lou et al. (Acta Paediatr Scand
76:560) added 160 mg/kg of tyrosine and found improved attention span in
patients with PKU. Pietz et al. in 1995 (J. Pediatr. 127:936 ) found no effect on
the brain of adults with high doses of tyrosine. Other formulations have been
tried but none have resulted in an acceptable method of treatment. Dotremont et
al, in 1995 used a formulation of LNAA 0.6 gms per kg with a low protein diet
and found negative nitrogen balance, with lysine the limiting amino acid.
•
We studied the effect of PreKUnil on PKU mice (Enu2/Enu2). A surprising
finding was that such mice showed a lower concentration of blood Phe. Taking
into account that the GI transporter (Table 1) for LNAA has different Km than the
blood brain barrier, a new formulation was undertaken.
The new formulation of LNAA (NeoPhe) was developed, by introducing changes
in concentration of some amino acid and addition of Lysine. In order to correct
the deficiency a new PreKUnil with lysine added has been introduced.
Table 1: Transport of LNAA
to the Brain
•
•
•
•
•
•
•
•
•
Phenylalanine (Phe)
Leucine
Tyrosine
Tryptophan
Methionine
Histidine
Isoleucine
Valine
Threonine
Km
0.12
0.15
0.16
0.19
0.19
0.28
0.33
0.63
0.73
Pardridge, Inborn Errors of Metabolism in Humans.
MTP Press, 1980.
Km App
0.45
0.53
0.58
0.71
0.77
1.10
1.30
2.50
3.00
Methods
Four patients, three female and one male, ages 25 to 38
years, with PKU took part in the study at University of
Texas Medical Branch, Galveston, Texas, U.S. The
patients where given NeoPhe tablets, 0.5gm/kg/day in
three divided doses to be taken with meals Blood Phe
was measured thrice at zero time, two weeks after
starting on NeoPhe and once a month for a period of 12
months. Patients were monitored for weight increase,
acceptability of pills. Physical was done once a month.
Results
• The individual blood Phe response to 0.5 g/kg of
NeoPhe is shown in Figures 1-5. The paired t-test for
the decline in blood Phe is p ≤ 0.0002. The genotype of
each individual is shown. The mean blood Phe levels
declined for each of the patients during the study period:
642mmol/L, 707mmol/L, 899mmol/L, and 869mmol/L. All
patients reached levels within NIH consensus report
recommendation.
• None of the patients gained or lost any weight beyond
the minor fluctuation of +/- 0.2Kg. There were no
complains regarding the number of pills or abdominal
discomfort, nausea or changes in bowel habits.
Figure 1
Effect of LNAA on patients with PKU
m mol/L Phe
2000
1500
1000
500
Pr
eav
er
ag
e
2w
k
1
m
o
2
m
o
3
m
o
4
m
o
5
m
o
6
m
o
7
m
o
8
m
o
9
m
10 o
m
11 o
m
12 o
m
o
0
Time
Figure 1: Effect of LNAA on 4 patients over a period of 12 months.
Patient 1
patient 2
Patient 3
Patient 4
Figure 2
m mol/L Phe
Effect of LNAA on Patient no 1
1600
1400
1200
1000
800
600
400
200
0
pre
2wk 1 mo 2 mo 3 mo 4 mo 5 mo 6 mo 7 mo 8 mo 9 mo
10
mo
11
mo
12
mo
Tim e
Figure 2: The patient showed a 40% decrease of blood Phe levels in the 12 month
period. (Female: 34 years, Mutation: Del I94 / unknown).
Figure 3
m mol/L Phe
Effect of LNAA on patient no. 2
1600
1400
1200
1000
800
600
400
200
0
pre 2wk
1
mo
2
mo
3
mo
4
mo
5
mo
6
mo
7
mo
8
mo
9
mo
10
mo
11
mo
12
mo
Time
Figure 3: The patient showed a 45% decrease of blood Phe levels in the 12 month
period. (Female: 25 years, Mutation: E280K / E280K).
Figure 4
m mol/L Phe
Effect of LNAA on Patient no. 3
1800
1600
1400
1200
1000
800
600
400
200
0
pre
2wk
1
mo
2
mo
3
mo
4
mo
5
mo
6
mo
7
mo
8
mo
9
mo
10
mo
11
mo
12
mo
Time
Figure 4: The patient showed a 42% decrease of blood Phe levels in the 12 month
period. (Female: 38 years, Mutation: IVS12nt-1g>a / P281L).
Figure 5
m mol/L Phe
Effect of LNAA on Patient no. 4
1800
1600
1400
1200
1000
800
600
400
200
0
pre
2wk
1
mo
2
mo
3
mo
4
mo
5
mo
6
mo
7
mo
8
mo
9
mo
10
mo
11
mo
12
mo
Time
Figure 5: The patient showed a 49% decrease of blood Phe levels in the 12 month
period. (Male: 30 years, Mutation: G46S / unknown).
Summary of the study
•
•
•
•
•
NeoPhe 0.5 g/kg
4 subjects
Mean age 32 years
1 males, 3 females
Mean decrease in blood Phe after two
weeks 831 µmol/L
• Average decrease in blood Phe 45 %.
Discussion and Conclusions
• Specific composition of large neutral amino acids, as in NeoPhe can
reduce blood Phe concentrations. Our studies show for the first time
that LNAA can effect the blood concentrations of Phe, which is the end
point of treatment of PKU. NeoPhe has been more effective than
PreKUnil in lowering blood Phe concentrations.
• Patients were able to take NeoPhe for a period of 12 months and were
happy with their blood Phe levels, they indicated that they felt “more
focused” at work. Patients with high protein intake and high
concentration of blood Phe will require higher amounts of NeoPhe in
order to effectively compete with Phe transport. Future studies should
include larger number of patients and neuropsychological tests need to
be added.
• To avoid Lysine deficiency, any product without lysine should not be
used.
References
•
•
•
•
•
•
•
•
•
•
•
•
Choi TB, Pardridge WM (1986) Phenylalanine transport at the human blood–brain barrier. J Biol Chem 261:
6536–6541.
Lou HC, Lykkelund C, Gerdes AM, Udesen H, Bruhn P (1987). Increased vigilance and dopamine synthesis by
large doses of tyrosine or phenylalanine restriction in phenylketonuria. Acta Paediatr Scand. Jul;76(4):560-5.
Dotremont H, Francois B, Diels M, Gillis P (1995) Nutritional value of essential amino acids in the treatment of
adults with phenylketonuria. J Inherit Metab Dis 18: 127–130.
Matalon R, Surendran S, Michals-Matalon K, et al (2003) Future role of large neutral amino acids in transport of
phenylalanine into the brain. Pediatrics 122: 1570–1574.
Moller HE, Weglage J, Wiedermann D, Vermathen P, Bick U, Ullrich K (1997) Kinetics of phenylalanine
transport at the human blood–brain barrier investigated in vivo. Brain Res 778: 329–337
Moats R, Guttler F, Koch R (1999) Blood–brain phenylalanine relationships in adults with phenylketonuria. J
Inherit Metab Dis 22: S1A01. MoatsRA, Koch R, Moseley K, et al (2000) Brain phenylalanine concentration in
the arrangement of adults with phenylketonuria. J Inherit Metab Dis 23: 7–14.
NIH Consensus Report on Phenylketonuria (2001) ‘Phenylketonuria: Screening and management of PKU’. US
Department of Health and Human Services, Public Health Services, National Institutes of Health, National
Institute of Child Health and Human Services.
Oldendorf WH, Szabo J (1976) Amino acid assignment to one of three blood–brain barrier amino acid carriers.
Am J Physiol 230: 94–98.
Pardridge WM (1982) Blood–brain barrier amino-acid transport: clinical implications. In: Cockburn F,
Gitzelmann R, eds. Inborn Errors of Metabolism in Humans. Lancaster, UK: MTP Press, 87–99.
R. Matalon , K. Michals-Matalon , G. Bhatia, E. Grechanina, P. Novikov, J. D. McDonald, J. Grady,S. K. Tyring,
F. Guttler (2006) Large neutral amino acids in the treatment of phenylketonuria (PKU) J Inherit Metab Dis
29:732–738.
Pietz J, Landwehr R, Kutscha A, Schmidt H, de Sonneville L, Trefz FK (1995) Effect of high-dose tyrosine
supplementation on brainfunction in adults with phenylketonuria. J Pediatr 127: 936–943.
Schindeler S, Ghosh-Jerath S, Thompson S, Rocca A, Joy P, Kemp A, Rae C, Green K, Wilcken B,
Christodoulou J (2007).The effects of large neutral amino acid supplements in PKU: An MRS and
neuropsychological study, Molecular Genetics and Metabolism, Vol 91, Pages 48-54.