Combination small molecule PPT1 mimetic and CNS-directed gene therapy as a treatment for infantile neuronal ceroid lipofuscinosis.

Infantile neuronal ceroid lipofuscinosis (INCL) is a profoundly neurodegenerative disease of children caused by a deficiency in the lysosomal enzyme palmitoyl protein thioesterase-1 (PPT1). There is currently no effective therapy for this invariably fatal disease. To date, preclinical experiments using single treatments have resulted in incremental clinical improvements. Therefore, we determined the efficacy of CNS-directed AAV2/5-mediated gene therapy alone and in combination with the systemic delivery of the lysosomotropic PPT1 mimetic phosphocysteamine. Since CNS-directed gene therapy provides relatively high levels of PPT1 activity to specific regions of the brain, we hypothesized that phosphocysteamine would complement that activity in regions expressing subtherapeutic levels of the enzyme. Results indicate that CNS-directed gene therapy alone provided the greatest improvements in biochemical and histological measures as well as motor function and life span. Phosphocysteamine alone resulted in only minor improvements in motor function and no increase in lifespan. Interestingly, phosphocysteamine did not increase the biochemical and histological response when combined with AAV2/5-mediated gene therapy, but it did result in an additional improvement in motor function. These data suggest that a CNS-directed gene therapy approach provides significant clinical benefit, and the addition of the small molecule PPT1 mimetic can further increase that response.

Infantile cystinosis.

Ten patients of nephropathic cystinosis were admitted during the period 1995-2000. Their mean age was 12 months. The signs of failure to thrive and advanced rickets were seen in all patients. Other features included polyuria, polydipsia, pathologic fractures and deafness. Laboratory findings included glucosuria, hyposthenuria, hypocalcemia, proteinuria and azotemia. Therapy with phosphocysteamine showed marked clinical improvement.

Lysosomal ceroid depletion by drugs: therapeutic implications for a hereditary neurodegenerative disease of childhood.

Neuronal ceroid lipofuscinoses (NCLs) are the most common hereditary neurodegenerative diseases of childhood. The infantile form, INCL, is caused by lysosomal palmitoyl-protein thioesterase (PPT) deficiency, which impairs the cleavage of thioester linkages in palmitoylated proteins, preventing their hydrolysis by lysosomal proteinases. Consequent accumulation of these lipid-modified proteins (constituents of ceroid) in lysosomes leads to INCL. Because thioester linkages are susceptible to nucleophilic attack, drugs with this property may have therapeutic potential for INCL. We report here that two such drugs, phosphocysteamine and N-acetylcysteine, disrupt thioester linkages in a model thioester compound, [14C]palmitoyl approximately CoA. Most importantly, in lymphoblasts derived from INCL patients, phosphocysteamine, a known lysosomotrophic drug, mediates the depletion of lysosomal ceroids, prevents their re-accumulation and inhibits apoptosis. Our results define a novel pharmacological approach to lysosomal ceroid depletion and raise the possibility that nucleophilic drugs such as phosphocysteamine hold therapeutic potential for INCL.

Effects of pre- and postnatal cysteamine exposure on renal function in the rat.

The safety of cysteamine after renal transplantation and during pregnancy is an important issue, since girls with cystinosis are in better health on cysteamine therapy and thus more likely to become pregnant. In the first study, cysteamine was given to pregnant rats on days 6.5-18.5 post conception in oral doses of 0, 37.5, 75, 100, and 150 mg/kg per day. The dams were sacrificed on day 20.5, the fetal kidneys removed and prepared for histological examination. In the second study, cysteamine was given to dams on days 6.5-19.5 post conception in oral doses of 0, 37.5, 50, and 75 mg/kg per day. Dams were allowed to give birth naturally and pups were given cysteamine on days 4-21 to yield the same oral doses of cysteamine given to the dam. Renal function was evaluated on day 35. Histological examination of fetal kidneys revealed no changes even in kidneys from fetuses with growth retardation and malformations. Furthermore, there were no alterations in renal function in offspring on day 35. These findings demonstrate that cysteamine therapy does not affect renal development in the rat. Further investigations will be required to prove whether cysteamine therapy has the potential to affect renal development in the human.

A study of the relative bioavailability of cysteamine hydrochloride, cysteamine bitartrate and phosphocysteamine in healthy adult male volunteers.

AIMS: Cysteamine, the only drug available for the treatment of cystinosis in paediatric patients, is available as the hydrochloride, the bitartrate and as sodium phosphocysteamine salts. It has been suggested that cysteamine bitartrate and phosphocysteamine are better tolerated and may have a better bioavailability than cysteamine hydrochloride. This has, however, never been demonstrated. METHODS: We compared the pharmacokinetics and tolerance of these three formulations of cysteamine in 18 healthy adult male volunteers in a double-blind, latin-square, three-period, single oral dose cross-over relative bioavailability study. RESULTS: No statistical difference was found between relative bioavailabilities, AUC (0, infinity) (geometric mean and s.d. in micromol l(-1) h: 169+/-51, 158+/-46, 173+/-49 with cysteamine hydrochloride, phosphocysteamine and cysteamine bitartrate respectively), Cmax (geometric mean and s.d. in micromol l(-1); 66+/-25.5, 59+/-12, 63+/-20) and tmax (median and range in h: 0.88 (0.25-2), 1.25 (0.25-2), 0.88 (0.25-2)) with each of the three forms of cysteamine tested. Bioequivalence statistics (90% confidence intervals) showed non equivalence of Cmax of cysteamine base as the only non equivalence of pharmacokinetics between the three formulations: 90% CI for Cmax relative ratios to cysteamine hydrochloride were [75.6-105.81 for phosphocysteamine and [74.2-124.2] for cysteamine bitartrate. The only significant adverse event was vomiting whose frequency was inversely correlated with body weight (Spearman's r=-0.76, P<0.001). The nature of the salt tested did not influence vomiting. CONCLUSIONS: While none of the three forms of cysteamine tested has a clear advantage over the others in terms of pharmacokinetics and tolerance profile, this should now however be addressed in patients treated for cystinosis during repeat administrations.

The treatment of cystinosis with cysteamine and phosphocysteamine in the United Kingdom and Eire.

Fifty-nine patients with cystinosis were treated with cysteamine or phosphocysteamine in the United Kingdom up to May 1990. Treatment was started at a median age of 3.2 years (range 0.6-24.8 years) and continued for a median duration of 3.0 years (range 0.01-1.2 years). At the end of the study, 46 (78%) patients remained on treatment. One patient developed end-stage renal failure and 6 died. Efficacy was assessed in the 44 pre-transplant patients. The United Kingdom pre-transplant patients had significantly lower plasma creatinine concentrations at 6 and 8 years than a historical group of patients who did not receive cysteamine (P < 0.0001 and P < 0.0003, respectively). There was no significant difference between pretreatment and final post-treatment height standard deviation scores, suggesting maintenance of growth rate. The leucocyte cystine concentration was less than the accepted upper limit of the treatment range (1 nmol 1/2 cystine/mg protein) in only 21% of determinations. There was no significant difference between the mean pre-treatment and final values of leucocyte cystine concentration. The mean final doses of cysteamine (33 mg/kg per day) and phosphocysteamine (37 mg/kg per day base equivalent) were less than the mean dose (51 mg/kg per day) used in a United States multicentre trial. We conclude that cysteamine treatment was beneficial, but further improvements might be achieved by an improvement in monitoring of therapy.

Influence of a radioprotector WR-638 on the lymphoid compartment of the irradiated rat thymus: a flow cytometric analysis.

The T cell composition of the thymus of X-ray irradiated (3.5 Gy) Wistar rat protected with WR-638 was analyzed by flow cytometry using monoclonal antibodies directed to the Thy 1.1, CD43, CD2, CD5, CD4, CD8 and class I and II MHC antigens. It was shown that this dose of X-rays caused cyclic changes in thymic cellularity manifested as: primary involution (until day 2), primary regeneration (from days 2 to 14), secondary involution (from days 14 to 21) and secondary regeneration (from days 21 to 30). WR-638 reduced the magnitude of thymocyte depletion in the primary involutive phase of the irradiated thymi, primarily as a result of protection of Thy 1.1high+ CD2low+ CD5high+ CD4+ CD8+ class I antigen high+ subpopulations of thymocytes. In the early regenerative phase, WR-638 accelerated the regeneration of CD4-CD8- and CD4-CD8+ thymocyte subsets, followed by subsequent increase of CD4+CD8+ and CD4+CD8- thymocyte subsets. Secondary involutive and regenerative phases in protected animals were characterized by higher absolute cell number of almost all thymocyte subpopulations in comparison with those in irradiated, non-protected animals.

[Radioprotective and therapeutic modulation of thymus gland regeneration in rats after x-ray irradiation]. / Radioprotektivna i terapijska modulacija regeneracije timusa pacova nakon X-zracenja.

There have been studied effects of cystaphos, gammaphos, hydroxyurea, polyadenyl-polyuridinic acids (poly A:poly U) as well as the combination of gammaphos and poly A:poly U, that is, cystaphos and superoxide dismutase on the thymus of Wistar and AO rats irradiated by the hard X-rays in the dose of 5 or 3.5 Gy. Changes were observed up to 30 days after irradiation. The most efficacious protective effect has shown cystaphos (358 mg/kg i.p. 20 min. after irradiation) in Wistar rats irradiated by the dose of 3.5 Gy. It lowered involutive changes and accelerated thymus regeneration. On the basis of phenotypic analysis of thymocytes it can be supposed that such a favourable effect is the consequence of a larger protection of the cortical (strong OX 7+) thymocytes. Differing from cystaphos, transplantation of the syngeneic cells of the bone marrow in AO rats irradiated by the dose of 5 Gy showed favourable effect on thymus regeneration in later phase after irradiation preventing secondary thymus involution.

[The effect of phenol derivatives on the antimutagenic activity of dextran]. / Vliianie proizvodnykh fenola na antimutagennuiu aktivnost' dekstrana.

The effects of dextran + hydrazine or amino derivative of dibunol and of dextran + cystafos derivatives with different degree of modification of their molecules on the mutagenic activity of gamma irradiation were studied using the micronucleus test in polychromatophilic erythrocytes of the mouse bone marrow. The effects of these compounds on differentiation of the erythroid series has also been studied. The mutagenic activity of gamma irradiation was most markedly inhibited by the copolymer dextran and the amino derivative dibunol. The optimal structure of copolymers was 1 heterocyclic link per 3 non-oxidized links of dextran, while the increasing number of active links in the dextran molecule insignificantly enhanced its antimutagenic effect. The studied compounds effectively protected erythropoiesis.

[Significance of ED50 and therapeutic indexes of various radiation-protective agent groups]. / Znacheniia ED50 i terapevticheskie indeksy razlichnykh grupp radioprotektorov.

Radioprotective agents are divided in 3 groups: (1) cystamine, AET, cystaphos, gammaphos, and thiogammaphos with ED50 (the dose that gives a half of the maximal protective effect) of 10(3)-10(1.6) mumol/kg and therapeutic index K = LD50/ED50 = 10(0)-10(1.6); (2) 5-methoxytryptamine, phenylephrine, serotonin, and norepinephrine with ED50 = 10(1)-10(0) mumol/kg and K = 10(1.8)-10(2,6); (3) clonidine and isoprenaline with ED50 = 10(-0.5)-10(-0.8) mumol/kg and K = 10(3)-10(4). Possible causes of these differences and advantages of low ED50 and high K are discussed.

Effects of oral phosphocysteamine and rectal cysteamine in cystinosis.

Diurnal variation in leucocyte cystine and the effects of equimolar single doses of oral phosphocysteamine and rectal cysteamine were studied in eight patients with cystinosis, aged 1.8-16.5 years. No significant diurnal variation in leucocyte cystine was found. Absorption of cysteamine was reduced after rectal administration compared with the oral dose: mean (SD) peak concentration 17.2 (6.3) mumol/l v 36.4 (5.5) mumol/l at 40 min and mean (SD) area under the curve 22.3 (14.3) v 59.4 (33.1) mumol/h/l. Oral phosphocysteamine significantly reduced the mean (SD) leucocyte cystine from 8.09 (0.47) to 3.26 (1.48) nmol 1/2 cystine/mg protein at three hours. At 12 hours the mean leucocyte cystine was significantly lower than the pretreatment concentration. Rectal cysteamine did not significantly reduce the mean leucocyte cystine concentration. In conclusion, phosphocysteamine suspension may be administered every 12 hours. Rectal cysteamine administration is feasible but higher doses are required before efficacy can be judged.

[The antimutagenic activity of compounds of modified polyglucin]. / Antimutagennaia aktivnost' soedinenii modifitsirovannogo poligliukina.

The effect of modified polygluquin compounds on gamma-irradiated nuclei of V-79 Chinese hamster cells has been studied. Antimutagenic properties of the compounds are determined by aldehyde groups and oxidized chains.

NIH conference. Cystinosis: progress in a prototypic disease.

OBJECTIVE: To review the history, basic defect, pathogenesis, clinical manifestations, diagnosis, and treatment of nephropathic cystinosis. DESIGN: Lysosomal membrane transport studies, clinical reports, and a historically controlled 7-year trial of oral cysteamine therapy. SETTING: University centers in the United States and Canada. PATIENTS: One hundred forty-eight children, aged 0 to 12, with nephropathic cystinosis before renal transplant, who had renal tubular Fanconi syndrome, failure to grow, corneal cystine crystals, and elevated leukocyte cystine; 34 patients, aged 9 to 29, after transplant, some with visual impairment, corneal erosions, pancreatic dysfunction, or neurologic deterioration. INTERVENTION: Before transplant, replacement of renal losses, and treatment with oral cysteamine (55 mg/kg body weight.d for 1 to 6 years) and topical cysteamine eyedrops (0.1%, 1 drop/h while awake, for 6 months). After transplant, oral cysteamine and symptomatic treatment of late complications. MEASUREMENTS AND MAIN RESULTS: Untreated patients reached renal failure at age 10. Oral cysteamine lowered leukocyte cystine over 80%, and in patients before transplant, improved growth and preserved renal function (mean creatinine clearance [+/- SE], 0.64 +/- 0.04 mL/s.1.73 m2 [38.5 +/- 2.5 mL/min.1.73 m2] in the cysteamine group compared with 0.50 +/- 0.03 mL/s.1.73 m2 [29.7 +/- 2.0 mL/min.1.73 m2] in controls; 95% CI for the difference, 1.8 to 15.8). Cysteamine eyedrops cleared the corneal crystals of two children less than 2 years old. CONCLUSIONS: Cystinosis is a lysosomal storage disease due to impaired transport of cystine out of lysosomes. In young children, growth can be improved and renal deterioration delayed or prevented by oral cysteamine. Nonrenal complications after transplant might be prevented with long-term oral cysteamine.

A comparison of the effectiveness of cysteamine and phosphocysteamine in elevating plasma cysteamine concentration and decreasing leukocyte free cystine in nephropathic cystinosis.

Cysteamine (beta-mercaptoethylamine, MEA) is currently used to treat children with nephropathic cystinosis. In this study MEA was compared to phosphocysteamine (MEAP), a phosphorothioester that tastes and smells better than MEA, with respect to its ability to elevate plasma MEA and deplete leukocytes of cystine. Studies were performed in six children with nephropathic cystinosis ranging in age from 2 to 10 yr. After equimolar oral doses of either MEA or MEAP plasma cysteamine was determined at various times for 6 h. MEA was determined by sodium borohydride reduction followed by high-performance liquid chromatography separation and electrochemical detection. Leukocyte cystine was measured before and 1 and 6 h after drug administration. Peak plasma MEA was obtained 30 min to 1 h after a dose and was not significantly different when MEA (48.6 +/- 10.7, mean +/- SD) or MEAP (54.1 +/- 20.2) was given. Significant plasma MEA concentrations were seen as early as 15 min after an oral dose, indicating rapid absorption. Analysis of vomitus indicated that hydrolysis of the phosphate group of MEAP occurs in the stomach. The percent decrease in leukocyte cystine content obtained with MEA administration (61.9%) was not significantly different from the decrease observed when MEAP was administered (65.3%). MEA and MEAP appear to be equally effective in their cystine-depleting properties.

[Stimulating effect of aminoethylisothiuronium on the immune response and interferonogenesis in irradiated mice]. / Stimuliruiushches deistvie aminoétilizotiuroniia na immune reaktsii i interferonogenez u obluchennykh myshei.

Aminoethylisothiuronium (AET) stimulated the formation of antibodies against sheep erythrocytes, not against E. coli, in X-irradiated (4 Gy) mice. The serum containing AET-induced interferon had the same effect. AET also promoted the rejection of the allogenic skin graft in mice irradiated with the same dose. In addition, AET and cystaphos stimulated the induction of interferon by the Newcastle disease virus in mice exposed to doses of 4, 5 or 6 Gy.