75th European Neuromuscular Centre International Workshop: 2nd Workshop on the Treatment of Muscular Dystrophy 10–12 December, 1999, Naarden, The Netherlands
Article Outline
- 1. Introduction
- 2. Update on current studies with steroids
- 3. Bone densitometry studies
- 4. Cochrane systematic analysis
- 5. Organization of national multicentric studies
- 6. Multinational studies
- 7. Treatment of other muscular dystrophies
- 8. Other therapeutic trials
- 9. Concluding session
- 10. Participants
- 11. Observers
- Acknowledgements
- Copyright
1. Introduction
The second workshop convened by the European Neuromuscular Centre (ENMC) on the treatment of muscular dystrophy was held in Naarden, The Netherlands, from the 10th to 12th December, 1999, and attended by 23 participants from 11 countries, all of whom had personal experience in the pharmaceutical treatment of muscular dystrophy. Their names are appended at the end of this report (Section 10).
In his opening remarks, Victor Dubowitz welcomed the participants, not only as the convenor of the workshop, but also in his new role as the Director of Therapeutic Studies Trials of ENMC, a new initiative started recently by the ENMC in order to promote workshops in relation to the therapy of neuromuscular disorders, in parallel with the well established multidisciplinary workshops aimed at the molecular genetic resolution of various neuromuscular disorders.
This was the first workshop under the new umbrella, and it is hoped that there will be an increasing number of such workshops over the coming years.
It was just 3 years since the first workshop on the treatment of muscular dystrophy was convened in December 1996. The main purpose of that workshop was to pool the experience at the time in relation to the use of steroids in Duchenne muscular dystrophy (DMD). The current workshop had considerably expanded its remit, and in addition to an update on the experience of various participants of the earlier workshop in relation to steroids in DMD, also included experience of steroids in other muscular dystrophies, other drugs under trial in the muscular dystrophies, and also, a review of other approaches to the treatment of muscular dystrophy, such as cell and gene transfer studies.
2. Update on current studies with steroids
B. Reitter (Mainz) presented his definitive data on the large-scale multicentric study he had organized in Germany in 1992 on a comparative study of deflazacort and prednisone without a placebo group. A provisional report had been presented at the first workshop, but the trial at that stage had not yet been completed.
Meanwhile, the data of the 2 year blind treatment period for 100 boys with DMD (age in years until loss of ambulation) are undergoing a final statistical evaluation and will be published in detail. Fourteen patients dropped out prematurely due to untolerated weight gain; the majority of these were treated with prednisone. Among the 80 patients who finished the study period without violation of the protocol, the weight gain was significantly higher in those who received prednisone; conversely, more boys on deflazacort developed cataracts (deflazacort, 16 out of 44; prednisone, one out of 36). All remained of slight degree throughout the study period. Other side-effects were of minor importance and did not necessitate stopping the medication. Both drugs (equipotent anti-inflammatory dosages, i.e. prednisone, 0.75 mg/kg; deflazacort, 0.9 mg/kg per day) were equally effective in almost completely preserving muscle performance, as judged by manual muscle testing using a ten-point scale. There were no significant differences in the timed motor functions (running, climbing stairs, etc.) between the medication groups, as well between the measures at the beginning and at the end of the 2 years. The expected bone-sparing effect of deflazacort compared with prednisone could not be proven by the urinary excretion of bone markers. Growth was impaired in all boys without difference according to the steroid. All reached a growth rate below the 3rd percentile after the second year of treatment. With the exception of those boys who were on the verge of losing ambulation, all wanted to continue the treatment after the individual study period using either steroid. Meanwhile, a total of 124 patients (from the five centres, which contributed most patients in the study) could be monitored up to the individual treatment periods of 6 years. The loss of muscle strength remained slight; nevertheless, some boys lost ambulation. Their individual courses do not allow one to hypothesize about the best time for the start of this treatment. Obviously, the boys who did not exhibit major side-effects within the initial year and did prove to retain their strength, continued to profit from the medication, although there has been a slight decline in muscle performance with time. None of these patients treated between 3 months and 6 years developed cardiomyopathy beyond a degree, which might be expected at that particular age and stage, and none experienced life-threatening infections. In two patients, cataracts became severe enough to necessitate lens replacement.
D.M. Bonifati (Padua) presented details of the ongoing studies in Padua on the use of steroids in DMD, which had been presented at the first workshop. Their double-blind, randomized, multicentric trial of deflazacort versus prednisone has been ongoing for about 3 years. Patient recruitment was started in December 1996, and included 18 molecularly characterized DMD boys from two neuromuscular centres (Pavia and Padua), with a mean age of 7.3 years. The children were randomized into two groups on the basis of age and functional abilities at the onset of the trial, and treated either with deflazacort (0.9 mg/kg per day) or prednisone (0.75 mg/kg per day). After 1 year, the drug schedule was switched to alternate day treatment, maintaining the same total dose. A clinical examination was performed every 3 months, and included an evaluation of the Medical Research Council (MRC) score on four limb muscles (deltoid and triceps muscles in the upper limb, and quadriceps femoris and ileo-psoas muscles in the lower limb), and the grading and timing of four functional performances (walking 10 m, climbing four steps, Gowers’ manoeuvre and rising from a chair).
A clear improvement in the first 6 months of therapy was present with respect to their historical controls, followed by a stabilization of the disease course for another 6 months. After the first year, a decline appeared in strength and functional performances. After 20 months, there were no significant differences between the two groups, in the MRC score or in their compound functional score. The MRC data and the slope of functional score were similar. The deflazacort treated group had significantly less weight gain than the prednisone group.
B. Lindvall (Linköping) presented further data in connection with the steroid trial, which had been initiated by K. Henriksson at the time of the first workshop. The aim of the trial was to assess whether a dose of 0.35 mg prednisolone/kg per day had the same positive effects on muscle strength and function, but milder side-effects than higher doses. The study could verify this positive effect in both DMD and Becker muscular dystrophy (BMD). As a result of the study, most centres in Sweden now use this low-dose regimen as a standard treatment of DMD. A re-evaluation of the participating boys is currently in progress. As several of the boys continued their medication after the end of the trial, it is now important to evaluate the long-term effects on muscle function, as well as side-effects.
M. Osawa (Tokyo) presented their experience with low-dose prednisolone, and the preliminary results of a national survey of the present status of steroid therapy for progressive muscular dystrophy in Japan. They have used steroids in 16 cases of DMD, confirmed by DNA deletion or muscle biopsy. When the treatment with steroids was started, ten cases were able to ascend a stairs with a handrail, one case was able to stand up from a chair, and two cases were ambulant only. There were three non-ambulant cases: two were able to shuffle, but not crawl; and one was able to sit, but could not shuffle. The age at initiation of the treatment ranged from 7 years and 7 months to 15 years and 8 months. The dose of prednisolone varied from 0.3 to 1 mg/kg per 2 days to obtain good compliance. The duration of treatment ranged from 11 to 44 months.
The average age at loss of ambulation in the group whose steroids were started at stage II (when they could ascend stairs with a handrail) was older than that in the two control groups. However, patients in whom treatment was started after stage III (unable to ascend stairs, but able to stand up from a chair) had no delay in loss of ambulation compared to controls.
When comparing the age at loss of each motor function in the two groups, the age at loss of ambulation and the loss of ability to walk on all fours was later in the group where prednisolone was started at stage II than in the group in whom treatment started later. There was some concern that the use of steroids early in the course of the disease may lead to aggravation of the disease in the later stages, as an improvement with steroids may lead to patients using their muscles more. The comparison of the average period that patients spent at each functional stage showed that patients who were treated while they were able to ascend stairs had a very short duration of stages III and IV (unable to stand up from a chair, but ambulant). However, patients also treated from an early stage had a longer duration at stages II and IV than the controls. So, these results suggest that steroids do not necessarily aggravate the disease in the later stages.
When they compared the loss of ability to ascend stairs with the initial dose of steroids, they found no indication that higher initial doses were any more effective. Similarly, when they compared the age at loss of ambulation with the initial dose of steroids, they found no tendency for bigger doses to have a better effect.
Even after patients have lost ambulation, we can see that prednisolone may improve the time taken to sit up, roll, and also, a transient regain of the ability to sit up and an improvement in upper body strength for a period of 6 months. It may also provide an improvement in the ability maintain a more stable sitting position, and in upper arm pain.
In summary, (1), they treated 16 DMD patients (13 still ambulant) with oral prednisolone, at doses of 0.32–0.88 mg/kg per 2 days, for periods of 11–47 months; (2), in patients who started prednisolone while still able to ascend stairs, the average age of loss of ambulation was improved to 11.2 years compared with untreated patients (10.5 years); (3), patients who started prednisolone after loss of ambulation had a longer duration in stage V than untreated patients; (4), while they observed some beneficial effects of prednisolone on preservation of motor function after loss of ambulation, from the results of the present analysis, we cannot show any clear improvement in the age at loss of further function; (5), there was no relationship between the dose and the age at loss of motor function; and finally (6), there were no severe side-effects associated with their alternate day regime of prednisolone.
Y. Shapira (Jerusalem) gave an update on his continued experience with the use of steroids in DMD. He started a prospective study of corticosteroid treatment in DMD patients in early 1991.
The total number of patients enrolled was 74, with an average of eight new patients each year. Of those, 26 had dropped out. The remaining 48 subjects were treated with either prednisone, at 0.75 mg/kg per day, or deflazacort, at 1.0 mg/kg per day, both given on a daily basis. The average duration of steroid therapy was 3.5 years (range, 1–9 years). Of these 48 patients, 25 reached 10 years and were still walking. Of the 23 subjects younger than 10 years, four had stopped walking. Of the patients older than 10 years, ten subjects are still walking independently; five are now aged 10, one aged 11, three aged 12 and one aged 14 years.
Of the remaining 15 subjects who stopped walking later than 10 years of age, three were at age 10, three at 11, two at 12, two at 13, one at 14, two at 15 and two at 16 years.
Muscle strength, measured using the modified ten-point MRC scale, revealed that the cumulative score for children who did not stop walking has been almost unchanged over the years, and remained at about 7 compared with the natural history drop of 0.34 points/year. The data show that long-term corticosteroids significantly improve the average muscle strength, and prolonged the ability of independent walking beyond the age of 10 years.
M. Kinali (London), who recently joined the Hammersmith team, has undertaken a comprehensive review of the patients on long-term steroids, previously reported by J. Taylor at the first workshop. The original selection of patients were the late ambulant ones, either independently or in orthoses. To date, 21 patients had been reviewed and the details were presented, particularly in relation to the side-effects of long-term steroid therapy.
The age at recruitment was 8.5 years (range, 5.5 years–11 years and 4 months). All 21 patients had a diagnosis of DMD, defined clinically and by genetic analysis. They were recruited during the first 5 years of the study, and were selectively late independent walkers. Prednisolone was given on an intermittent low-dose schedule (0.75 mg/kg per day for the first 10 days of each calendar month). The average length of treatment with prednisolone was 1 year and 9 months. One patient discontinued the treatment within 3 months, whereas nine boys continued for longer than 2 years. The median age at discontinuation of prednisolone was 10 years and 8 months (range, 6 years and 9 months–12 years and 10 months). The median age at loss of independent walking was 9 years and 7 months (range, 6 years and 9 months–13 years). Two boys were able to walk independently up to their 13th birthdays. Rehabilitation with knee–ankle–foot orthoses was feasible in 18 patients. Of those rehabilitated, 10 boys continued prednisolone for a median of 1 year (6 months–3 years). Ambulation was finally lost at a median of 11 years and 3 months (range, 8–14 years). Fourteen patients developed scoliosis between 11 years and 15 years and 8 months. Four of them successfully underwent spinal fusion surgery.
Side-effects were noted in several patients. The most troublesome side-effect was mood/behavioural change, which was documented in ten patients. Patients presented as moody and aggressive (4/21) or with temper tantrums (4/21). Only those who had started prednisolone at an earlier age experienced hyperactivity or cheerfulness. Abnormal weight gain was evident in nine patients who had crossed at least two percentiles on the growth foundation chart within 2 years of the onset of treatment. Prednisolone was withdrawn at this stage. A significant number of patients (nine of the 21) had a history of bone fractures related to injuries (falls, vigorous physiotherapy), but only three of them whilst on prednisolone.
Other side-effects noted less often were cushingoid features, gastrointestinal complaints and headaches. Only one patient had transient systolic hypertension after the first 10-day course of prednisolone. This was carefully monitored, and subsequently settled without intervention. We had no evidence of cataracts on clinical examination. The average weight gain during the second year since the initiation of treatment was similar amongst those who had started prednisolone before or after 8 years of age.
V. Dubowitz (London) gave a follow-up of the 4-year-old boy he described at the time of the first meeting, who had displayed a remarkable response to an intermittent schedule of low dosage prednisone, (0.75 mg/kg per day for the first 10 days of each month), with a complete remission of the signs of DMD when assessed 1 year after the initiation of treatment, at the time of the first workshop. At a recent reassessment, some 4 years after initiation to the treatment, he is still free of any signs of muscular dystrophy, apart from some weakness of neck flexion and some increasing difficulty in going up stairs. The original regime of 10 days at the beginning of each month was changed from 10 days on and 10 days off.
He also presented details of a second boy, in whom treatment had been commenced at around 4 years of age, and who had also shown a marked improvement on steroids, and had now had 4 years of follow-up since the initiation of treatment. He had also remained remarkably stable after the initial improvement, until about 6 months ago, when he began experiencing increasing difficulty in running and going up stairs, and had developed a full Gowers’ manoeuvre of about 10 s in getting up from the floor, compared with an early ability, with a minimal Gowers’ of under 4 s. A third boy also given the steroid regime intermittently at 4 years of age had shown a response, and has had about 2 years of follow-up to date, and remained stable. All three of these boys have shown no side-effects of the steroid therapy, and have remained at around the 50th centile for weight and height.
3. Bone densitometry studies
There were three presentations on bone densitometry studies in relation to DMD and the potential effect of steroids.
N. Goemans (Leuven) presented data on bone metabolism and bone mineralization in ambulant DMD boys (Buyse et al., Eur J Ped Neurol 3(6):A110) In DMD, the exact incidence and extent of glucocorticoid-induced bone loss has not yet been properly addressed. As potential underlying disease-related effects on bone may be confounding in such studies, data regarding bone turn-over and bone density in ambulant DMD boys were collected before treatment with steroids, to measure the extent of changes in bone turn-over and bone density due to muscle weakness, compared with healthy age-matched controls. The methods included bone mineral density measurements with dual energy X-ray absorptiometry (DEXA), bone turn-over estimation with biochemical markers (serum human osteocalcin and bone-specific alkaline phosphatase, 24 h urinary excretion of deoxypyridinoline) and serum 25-OH vitamin D. In the DMD group, the bone mineral density (lumbar spine, lower limbs and subtotal body) markers of osteoblast activity, and serum 25-OH vitamin D levels were significantly lower, indicating that the ambulatory phase of DMD is associated with significant osteoporosis and 25-OH vitamin D deficiency. The osteoporosis represents an imbalance or uncoupling between bone formation and resorption, caused by a differential effect of muscle weakness on osteoblast and osteoclast activity. The fracture risk is clearly increased by a combination of muscle weakness-associated falls and osteoporosis. An ongoing prospective study is currently looking at the effects of glucocorticoids on bone metabolism in ambulatory DMD.
A. Manzur (London) presented the results of DEXA scanning of boys with DMD treated with an intermittent schedule of prednisolone, 0.75 mg/kg, for the first 10 days of each month (Dubowitz V. Neuromusc Disord 1991;1(3): 161–163; Sansome et al. Neuromusc Disord 1993;3:567–569) All scans were performed on a LUNAR DEXA scanner, and the results of lumbar spine bone densitometry were analyzed. This is measured reliably, and is an early and sensitive indicator of fracture risk. Between 1992 and 1998, 36 DEXA scans were performed on 29 boys with DMD. The mean age at scanning was 9.6 years. Group 1 was comprised of nine boys (mean age, 9.1 years; range, 5–12.5 years) who had a DEXA scan, but were never treated with steroids. All of them had bone mineral density Z scores in the negative range. Twenty boys had DEXA scans while on prednisolone, 0.75 mg/kg per day, for the first 10 days of each calendar month, and the duration of treatment was up to 36 months. The eight boys treated with prednisolone for at least 18 months constituted group 2. Both groups were similar for age and mobility status. The mean lumbar spine bone mineral density of group 2 was higher compared with group 1, raising the possibility of a relative osteoporosis-sparing effect of the intermittent prednisolone regime and the beneficial effect of improved mobility on bone deposition. Four boys had serial DEXA scans while on steroids (duration, up to 30 months), and no further reduction of bone mineral density was noted. Dr Manzur observed that bone mineral density is lower in boys with DMD compared with healthy age-matched boys, and concluded that prednisolone in a regime of 0.75 mg/kg per day for the first 10 days of every calendar month for periods of up to 3 years did not result in further reduction. He recommended that children with DMD should have baseline DEXA scans to detect osteoporosis prior to the initiation of steroid therapy, and that consideration should be given to the intermittent regime of prednisolone in view of decreased side-effects. Future studies should address the need for calcium and Vitamin D supplements, and perhaps, drugs such as etidronate of aldronate for children on long-term therapy with corticosteroids.
H. Topaloglu (Ankara) presented his experience with calcium, 500 mg/day, and vitamin D, 800 u/day, supplementation in a series of 45 ambulant boys with DMD on prednisolone, 0.75 mg/kg, on alternate days. The study compared the patients on prednisolone receiving and not receiving supplementation, respectively. Bone mass measured by DEXA scans was invariably decreased in the group not receiving supplementation, whereas it was preserved in children with supplementation, more so in the early initiated group. Biochemical markers of bone resorption were either increased or unchanged in the non-supplemented group, and were found to be decreased in the supplemented group. It was concluded that low-dose prednisolone therapy induces bone loss in boys with DMD, even when they are ambulant, and calcium and vitamin D appear to prevent it. This is a protective effect, rather than corrective, and is more effective if given early.
4. Cochrane systematic analysis
A. Manzur (London) discussed the Cochrane systematic review of corticosteroids in DMD. The Cochrane Collaboration is an international institution dedicated to preparing, maintaining and disseminating systematic reviews of the effects of health care. Within the Cochrane Neuromuscular Diseases Review Group, Dr Manzur is undertaking a systematic review of steroids in DMD. The steps of the review will entail developing a protocol for reviewing the studies, identification of all studies of steroids in DMD, writing to researchers for unpublished data, a systematic review of the data with meta analysis, and publication of the review in a medical journal and the Cochrane library. The review will be updated on a regular basis to incorporate future studies.
5. Organization of national multicentric studies
B. Reitter (Mainz) discussed the logistics in relation to his multicentric study of steroids in DMD conducted in Germany. In the absence of appropriate laboratory parameters correlating with the clinical course, therapeutic studies have to rely on clinical observation, testing of muscle performance, and timed motor functions. The use of myometers turned out to be less reliable than manual muscle testing; both depend on the boys’ co-operation. A thorough judgement about wanted and unwanted effects of drugs on the course of the muscular dystrophy requires a sufficient period of treatment and observation, probably not less than 6 months; the German study group felt that 2 years might be adequate. In order to recruit a sufficient number of patients, multicentre approaches seem advisable, provided sufficient expertise in each centre does ensure reliable data. The comparability of such data requires the repeated common training of testing (especially manual muscle testing). As many patients as possible should be involved in structured trials, using the same strict criteria, to enable parallel tests of several candidate drugs in order to replace the steroid treatment by agents burdened with less side-effects. However, such approaches will require considerable efforts in funding.
C. Angelini (Padua) discussed his previous collaborative studies in Italy, and his recent plans for further multicentric collaborative studies. Six clinical groups with the co-ordinating centre of Padova collected 60 DMD children, and planned a new trial to address the question if early steroids are useful to prolong the age of loss of Gowers’ sign, that occurred in their natural history controls at the average age of 8 years (Fanin M et al. Muscle Nerve 1999;18:1115–1120), and to delay the age of loss of independent ambulation which occurred in their natural history study of 49 cases at 10.4 years (±1.7 years). He was planning to assess the value of continuous daily steroid in young cases for 1 year, followed by alternate day therapy, versus placebo, and also a comparison of two different dosage schedules. As he had not been able to get funding for the project, he was now contemplating a collaboration with the UK multicentric study.
A. Manzur (London) discussed the proposed UK collaborative study on the evaluation of the long-term effect of steroids on function, with loss of ambulation as an endpoint of the study. Fourteen different centres have now agreed to co-operate in this study. The proposed multicentre randomized, placebo-controlled, double-blind trial will assess the long-term functional efficacy and safety of intermittent pulsed prednisolone in 190 ambulant boys with DMD, recruited between the ages of 4 and 7 years. Initial biochemical and bone densitometry screening will rule out contraindications to steroid use. Patients randomized to active treatment will be given oral prednisolone, 0.75 mg/kg per day, 10 days on, 10 days off, in repetitive cycles. Controls (patients randomized to placebo treatment) will be given placebo tablets in exactly the same manner.
Regular assessments for muscle strength, function and possible side-effects will be performed according to a set protocol. Guidelines for the management of possible side-effects have been incorporated in the trial protocol. The treatment and follow-up will be for 5 years. The primary outcome measure is the loss of independent ambulation, and the secondary outcome measures are inability to rise independently from the floor and muscle strength, as measured by the %MRC score. Statistical analysis will be based on intention to treat. Data will be forwarded to the data analysis group for efficacy monitoring, and to the independent data monitoring committee for the surveillance of any adverse effects. This study should give a conclusive answer as to whether oral corticosteroids alter the natural history of DMD by prolonging ambulation.
6. Multinational studies
G. Buyse (Leuven/Washington, DC) discussed the multicentre/multinational studies being set up by the Co-operative International Neuromuscular Research Group (CINRG) in relation to the short term, as well as a more long-term assessment of new potential treatments of muscular dystrophy. CINRG is a newly established international collaborative group of clinical centres that envisages multiple multicentre therapeutic trials in muscular dystrophies. In their first trial, CINRG is assessing the efficacy and safety of two compounds in DMD that were identified by the drug screening studies in the mdx mouse model (Granchelli J et al. Neuromusc Disord 2000;10:235–239) (see Section 8.3). To enable high-capacity multicentre studies, CINRG has developed an infrastructure that includes the electronic data collection of manual and quantitative muscle strength testing and of patient safety information, and electronic transmission to a central database at the group's co-ordinating centre.
7. Treatment of other muscular dystrophies
7.1. Sarcoglycanopathies
T. Voit (Essen) reported details of a 13-year-old Iranian girl with a homozygous mutation in exon 5 (Q141P) of the γ-sarcoglycan gene. She had developed the first symptoms of weakness at 8 years, and showed rapidly declining muscle power at 13 years. In addition, she suffered from palpitations, and 10.843 ventricular extrasystoles were detected by 24 h Holter monitoring. She was started on prednisone, 0.75 mg/kg per day, 10 days on, 10 days off, which was subsequently reduced to 0.5 mg/kg after one cycle. She showed an immediate benefit, with improvement of muscle power, which was assessed by ergometry. The time for which she could sustain 30 W increased from 140 to 240 s. The climbing of stairs increased from 17 to 30–36 stairs without a break. Her CK dropped from levels between 1400 and 7000 to 213–965 U/l, although she was more active. The cardiac arrhythmia disappeared within a week. The effect of therapy was sustained for 7 months without deterioration.
He also reported two other anecdotal cases. One patient with γ-sarcoglycanopathy who had been unable to rise from the floor at the age of 9 years when he was started on continuous prednisone (0.4–0.5 mg/kg). He had remained ambulant for 5 years under this regimen, and can currently walk 200 m. A patient with a homozygous missense mutation (ARG 77CYS) in the α-sarcoglycan gene was started at the age of 14 years on prednisone, 0.75 mg/kg, on a 10 days on, 10 days off schedule because of severe muscle pain after exercise and progressive weakness. He had preserved muscle power (Gowers’ time, 10 s in 1996, and 10 s in 1999) and a disappearance of muscle pain under steroid treatment.
F. Hentati (Tunis) reported the results of an open label trial of prednisone in 37 patients with autosomal recessive limb girdle muscular dystrophy (LGMD2) compared with 14 DMD patients.
The patients were selected among consecutive LGM2 and DMD in patients of the department of neurology on the following criteria: muscle weakness involving both girdles, progressive course, high CK, dystrophic features on muscle biopsy, with normal dystrophin for LGMD2 and absence of dystrophin for DMD. The majority of LGMD2 patients share a Δ521 mutation of the γ-sarcoglycan gene. Prednisone therapy was started at daily dose of 75 mg/kg per day. The patients were assessed monthly until the fourth month, and then at 6, 9 and 12 months. The evaluation of muscle strength was performed according to the MRC scale; 32 muscles were assessed and the total score was converted to a percentage (%MRC). Functional stage was evaluated according to the classification of Vignos et al. (1963). Clinical examinations and laboratory tests were periodically performed in order to evaluate any corticosteroid side-effects.
At the entry to the trial, the mean age of the patients was 15.3±6.8 years for LGMD2, and 11.3±3.5 years for DMD patients. The mean duration of the disease, as well as the average MRC score, was comparable between the two groups.
The evaluation of average MRC scores over time showed a mild, but significant improvement in LGMD2 and DMD. This improvement was more obvious during the first 3 months of the trial, and furthermore, average MRC scores became stabilized. However, the improvement was perceptible only on the MRC score, but not in the functional stages. The wide variability in the natural course of LGMD2, even between siblings sharing the same mutation, made the individual assessment of the effect of corticosteroids very difficult. The MRC score improvement was more noticeable in patients with shorter disease durations, and in those with an earlier stage of the disease (stage, <3).
No patient with a clinical stage higher than 3 followed the treatment after 6 months. The serum CK decreased from the first month of treatment, and again reached the initial value at the sixth month in limb girdle muscular dystrophy (LGMD) patients, and remained variable in DMD patients. Thirty LGMD and 13 DMD patients completed 6 months of treatment, whereas 13 LGMD and 12 DMD patients followed the treatment over 1 year. The most frequent side-effect was weight gain, which was observed in 30 patients (20 gained less than 10%, ten gained between 10 and 20%, and ten gained more than 20% of their weight).
Hentati concluded that corticosteroids seem to have similar effect in LGMD2 and DMD patients. They lead to a mild improvement of muscle strength, during the first 3 months of the treatment. The effect is more obvious when treatment is given in the early stage of the disease and to younger patients.
N. Miladi (Tunis) commented that in the LGMDs, the marked variability in the expression of the disease from one patient to another, in the same family and from one family to another, makes the analysis of the response to prednisolone treatment uncertain. An apparent striking positive response to prednisolone may correspond to a low-grade severity form of sarcoglycanopathy, which is the case in 75% of this type of muscular dystrophy.
8. Other therapeutic trials
8.1. Creatine
A number of participants had experience with the administration of creatine to patients with different forms of muscular dystrophy.
F. Hanefeld (Göttingen) presented data on creatine monohydrate supplementation in 28 patients with muscular dystrophies (DMD=13, BMD=9, FSHD=5). Children below the age of 12 years received 6–8 g/day, while those older than 12 years received 10 g. There was 1 day/week without creatine supplementation. The inclusion criteria were ability to walk, age below 30 years, a typical clinical picture of raised CK and typical histology; in DMD and BMD patients, characteristic dystrophin staining and/or molecular genetic confirmation. Examinations were carried out on day 0 and at 3, 6 and 12 months, using tests for time-functions, strength, endurance (bicycle ergometry) and vital capacity. The results were that oral creatine supplementation increased the performance in slowly progressing dystrophies (BMD: strength, +7%; endurance, +8%; vital capacity, +11%). In patients with DMD, no permanent improvement or stabilization was noticed, with the exception of an improved vital capacity (+29%). Self-estimation was mainly positive, no serious side-effects could be observed. The majority of patients/parents reported an improvement in the ability to perform daily mental and physical activities.
The effect of early supplementation in DMD with creatine is at present under consideration.
W. Müller-Felber (Munich) reported a placebo-controlled study with creatine-monohydrate in 32 patients with various forms of muscular dystrophy (DMD, BMD, LGMD and facioscapulohumeral dystrophy (FSHD)). Patients received either creatine (5 g for children, and 10 g for adults/day), or placebo, for 8 weeks each in a crossover design. Before and after each treatment period, the response to treatment was evaluated, using MRC scales, the neuromuscular symptom score (NSS), vital capacity and the patient's own assessment of improvement. No side-effects were found. There was a mild, but significant improvement using MRC, NSS, and the patient's own assessment on comparing the active drug with placebo administration. At the moment, the effect of creatine in congenital myopathies and myotonic dystrophy is under investigation. A long-term study in patients with DMD has also been started.
J.M. Burgunder (Bern) briefly presented the exploratory study conducted in Berne on the use of creatine in a placebo-controlled, double-blind protocol in patients over 18 years of age with different forms of muscular dystrophy, including BMD, DMD, LGMD and FSHD types. Clinical scales, biochemical measurements and the MR spectroscopic parameter were used. The data are now being analyzed. No major side-effects occurred.
B. Lindvall (Linköping) reported on a study of creatine in relation to DMD co-ordinated by T Sejersen in Stockholm in co-operation with Linköping. They have recruited 38 boys into the study, which was designed as a double-blind crossover, placebo-controlled randomized study. An evaluation of muscle strength and function, as well as heart and lung function, showed that no positive effects were achieved by creatine treatment. The data are preliminary and are currently being assessed; there are more results to be analyzed.
8.2. Any other drugs
C. Angelini (Padua) drew attention to the recent the study by Barton Davis et al. (J Clin Invest 1999;104(4):375–381) exploring the potential therapeutic effects of aminoglycoside antibiotics on mdx mice, which have a premature stop codon in the dystrophin gene. He discussed the possibility of setting up clinical trials of gentamycin in DMD for the approximate 10% who have a stop codon mutation comparable to that of the mdx mouse. Such a trial should be done on selected DMD patients, with a demonstrated stop codon, in a hospital setting, at the maximal gentamycin therapeutic dose, monitoring accurately for gentamycin plasma levels and its most relevant side-effects. The endpoints of the study would be the expression of dystrophin in muscle biopsies, and clinical safety and efficacy. A. Emery (Exeter, ENMC) pointed out that only a proportion of this 10% of cases with a stop codon might have the same stop codon as the mouse, and one had to weigh the, as yet unproven, therapeutic benefit against the known nephrotoxic and ototoxic effects of gentamycin.
8.3. Basic studies
G. Buyse (Leuven) presented details on the use of the mdx mouse as a screening model for potentially effective therapeutic agents in relation to muscular dystrophy. Since the identification of the dystrophin gene and protein as being causative of DMD, a number of mouse, dog and cat models were quickly identified which are homologous to DMD biochemically (dystrophin deficiency of muscle) and genetically (loss-of-function mutations of the dystrophin gene). Over recent years, these animal models have been instrumental in research into dystrophin function and pathophysiological processes in dystrophin-deficient muscles. Despite discordance in clinical presentations and progressions between the human disease and the homologous animal counterparts, the general consensus is that these dystrophin-deficient animal models are good models for DMD. One approach that has shown particular promise in developing novel therapeutics for DMD is the development of experimental systems through which pharmacological agents can be screened in the mdx animal model for possible efficacy in human patients. Exercise exacerbates the mdx mouse phenotype, causing a quantifiable progressive weakness. This knowledge has been further developed into a drug screening protocol using exercised mdx mice, with a relatively crude, yet effective, whole-body strength assay for drug efficacy (Grancelli et al. Neuromusc Disord 2000;10:235–239). This system allows large-scale screening of pharmacological agents capable of increasing the strength of dystrophic muscles, and the initial screen has shown promising agents which target specific aspects of the pathophysiology of dystrophin deficiency. Whether compounds which are beneficial in the mdx model will likewise be beneficial in human DMD patients remains uncertain, and this is currently being investigated by the CINRG (see Section 6).
T. Partridge (London) reviewed the current status in relation to cell therapy and gene therapy in muscular dystrophy. This presentation began with an overview of the potential strategies for genetic therapies for DMD. The mechanisms, which have been shown to be capable of inserting genes into skeletal muscle, were outlined, and the advantages and disadvantages of each were discussed. In general, there is little difference in the overall efficacy between the various recombinant adenoviral vectors, except perhaps for the adeno-associated vectors which seem to be more efficient than adenoviral or retroviral vectors at transducing mature muscle fibres, but cannot carry genes as large as those encoding dystrophin. It is, however, the subject of a proposed trial for the LGMD associated with γ-sarcoglycan deficiency, and is capable of carrying genes of this size. The major unsolved problems of all gene therapies are those of immune responses against the viral vector and the products of the introduced genes, and obtaining efficient distribution of the gene to all of the major muscles of the body. At present, all potential gene therapies are largely restricted to the region of muscle close to the injection site. A number of studies are exploring the idea of the vascular distribution of gene vectors.
There is increasing evidence of myogenic stem cells in muscle which can be passaged through a series of muscles, which are slowly-dividing in tissue culture and constitute the minority of myogenic cells which will survive transplantation and proliferate in vivo to participate in the repair of muscle. Multipotential stem cells, which can reconstitute the haematopoietic system of the bone marrow, disperse through the vasculature and participate in muscle fibre regeneration, have also been demonstrated recently. This mechanism is of biological interest, but, at present, operates too rarely and sporadically to be of therapeutic value. Much of the current work is directed at identifying and purifying these stem cell-like muscle precursors, with the idea of increasing their efficiency in performing these functions.
9. Concluding session
A table was drawn up in relation to the current regimes used in different centres with steroids in DMD, either as part of ongoing controlled trials or open therapy regimes. This revealed the remarkable range and diversity of different schedules, as well as the use of different steroids at different centres. There was further discussion on the possibility of different European centres participating in the multicentric UK study on intermittent schedule prednisolone in early cases of DMD. It seemed possible that nine other centres might be able to participate.
A small working group was also established to assimilate data from different centres specifically in relation to the number of patients with classical proven DMD treated with steroids, who are still independently ambulant beyond the age of 12 years. This might provide some indication of the long-term benefits of the studies and their potential influence on the natural history of the disease. This could considerably help the time-scale of the study.
A further meeting of the consortium is planned for approximately 12–18 months, and in the interim, a 1-day meeting might also be arranged for the participants in the UK therapeutic trial.
10. Participants
Professor Corrado Angelini (Padua, Italy)
Dr Domenico Marco Bonifati (Padua, Italy)
Dr Jean-Marc Burgunder (Bern, Switzerland)
Dr Gunnar Buyse (Leuven, Belgium)
Professor Victor Dubowitz (London, England)
Professor Alan Emery (Exeter, England/ENMC)
Dr Nathalie Goemans (Leuven, Belgium)
Dr Imelda J.M. de Groot (Amsterdam, The Netherlands)
Professor Folker Hanefled (Göttingen, Germany)
Professor Faycal Hentati (Tunis, Tunisia)
Dr Maria Kinali (London, England)
Dr Bjorn Lindvall (Linköping, Sweden)
Dr Adnan Manzur (London, England)
Professor Najoua Miladi (Tunis, Tunisia)
Dr W. Müller-Felber (München, Germany)
Dr Makiko Osawa (Tokyo, Japan)
Professor Terry Partridge (London, England)
Professor Bernd Reitter (Mainz, Germany)
Professor Yehuda Shapira (Jerusalem, Israel)
Dr Beril Talim (Ankara, Turkey)
Professor Haluk Topaloglu (Ankara, Turkey)
Professor Thomas Voit (Essen, Germany)
11. Observers
Dr Nina Barisi (Zagreb, Croatia)
Professor Anton Zupan (Lubljana, Slovenia)
Acknowledgements
This meeting was made possible thanks to the financial support of the Wellcome Trust, and the ENMC and its main sponsors, Association Francaise contre les Myopathies, Italian Telethon Committee, Muscular Dystrophy Group of Great Britain and Northern Ireland, Vereniging Spierziekten Nederland and Deutsche Gesellschaft für Muskelkranke, as well as its associate members, Unione Italiana Lotta alla Distrofia Muscolare, Schweizerische Stiftung für die Erforschung der Muskelkrankheiten and Muskelsvindfonden. The authors are also most grateful to Professor A.H. Emery for his scientific advice, and Michael Rutgers and Mira Klein for their excellent organizational support.
PII: S0960-8966(00)00126-7
© 2000 Elsevier Science B.V. All rights reserved.
