IGF1 as a Potential Treatment for Rett Syndrome: Safety Assessment in Six Rett Patients

Abstract

Rett syndrome (RTT) is a devastating neurodevelopmental disorder that affects one in ten thousand girls and has no cure. The majority of RTT patients display mutations in the gene that codes for the methyl-CpG-binding protein 2 (MeCP2). Clinical observations and neurobiological analysis of mouse models suggest that defects in the expression of MeCP2 protein compromise the development of the central nervous system, especially synaptic and circuit maturation. Thus, agents that promote brain development and synaptic function, such as insulin-like growth factor 1 (IGF1), are good candidates for ameliorating the symptoms of RTT. IGF1 and its active peptide, (1-3) IGF1, cross the blood brain barrier, and (1-3) IGF1 ameliorates the symptoms of RTT in a mouse model of the disease; therefore they are ideal treatments for neurodevelopmental disorders, including RTT. We performed a pilot study to establish whether there are major risks associated with IGF1 administration in RTT patients. Six young girls with classic RTT received IGF1 subcutaneous injections twice a day for six months, and they were regularly monitored by their primary care physicians and by the unit for RTT in Versilia Hospital (Italy). This study shows that there are no risks associated with IGF1 administration.

Figures

Figure 1

IGF1 serum levels during the treatment. IGF1 levels in the blood were tested at each hospitalization: D0 (first day of treatment, before IGF administration), D90 (90 days after the first IGF1 administration), D180 (180 days after the first IGF administration, last day of IGF1 treatment), D270 (270 days after the first IGF administration), and D365 (365 days after the first IGF administration). The dotted lines represent the normal range of IGF1 in each patient. The amount of IGF1 is expressed in ng/mL and reported for each patient, and it is color-coded: S1: blue, S2: red, S3: green, S4: purple, S5: cyan, and S6: orange. The data for S6 at D270 is not available. The serum levels of IGF1 rose for each patient during the treatment and returned back to control levels after the end of the treatment.

Figure 2

Growth parameters progression during IGF1 treatment. The figure reports the increase/decrease in weights (a), height (b), and head circumference (c) in each patient for one year, starting from Day0, D0 (first day of treatment, before IGF administration). The measurements were taken at D90 (90 days after the first IGF1 administration), D180 (180 days after the first IGF administration, last day of IGF1 treatment), D270 (270 days after the first IGF administration), D365 (365 days after the first IGF administration). The dotted lines represent the start (D0) and the end (D180) of the treatment. Each patient is color-coded: S1: blue, S2: red, S3: green, S4: purple, S5: cyan, and S6: orange. (a) Changes in body weight are expressed in kgs. There is an increase in body weight for each patient, with the exception of S2, who after D90 shows a decrease in body weight. The increase between D0 and D90 is significant (Wilcoxon test). (b) Changes in height are expressed in cms. The patients show a significant increase in height between D0 and D90 (Wilcoxon test). (c) Changes in head circumference are expressed in cms. The patients show an initial—but not significant—increase in head circumference between D0 and D90.

Figure 3

Glycemia values in Subject 1. Glucose blood levels were registered by the caregiver and recorded in the journal. The measurements were taken with a home device that the caregiver was trained to use on D0. On the X-axis are reported the days when the single measurements were taken, on the Y-axis are reported the glucose levels. For each measure the label shows the condition: blue filled diamond: full stomach, empty blue diamond fasting: and black filled diamond: vomit episode. The horizontal black line represents the threshold below which it was considered hypoglycaemia (glucose value 50).

Figure 4

Seizures outcome during IGF1 treatment. The figure shows the outcome of seizures during one year starting with D0. The dotted lines represent the start (D0) and the end (D180) of the treatment. Each patient is color-coded: S1: blue, S2: red, S3: green, S4: purple, S5: cyan, and S6: orange. The black vertical lines represent seizures episodes. The color-coded horizontal straight lines represent the therapy for seizures (valproic acid), while the dashed color-coded lines represent the IGF1 treatment that lasted from D0 to D180. Patients S1, S2, and S3 had seizures before the start of IGF1 treatment, and they were simultaneously treated with valproic acid and IGF1. S6 did not develop seizures. S4 had one single episode of seizures around D90, and the treatment with valproic acid started only after D180, when the seizures become frequent. S5 showed frequent seizures around P90 and the treatment with valproic acid started immediately.

Figure 5

Clinical assessment of IGF1 treatment on breathing. The graph reports the clinical evaluation of respiratory activity at each visit compared with the previous observation. D0 (first day of treatment, before IGF administration), D90 (90 days after the first IGF1 administration), D180 (180 days after the first IGF administration, last day of IGF1 treatment), D270 (270 days after the first IGF administration), and D365 (365 days after the first IGF administration). The dotted lines represent the start (D0) and the end (D180) of the treatment. Each patient is color-coded: S1: blue, S2: red, S3: green, S4: purple, S5: cyan, and S6: orange. The starting score at D0 was 0, and it was decreased or increased if the respiration improved or worsened, respectively. All the patients, with the exception of S1, showed an improved respiratory activity during IGF1 treatment. The improvement across all the patients is significant between D0, and D90 (Wilcoxon test). After the IGF1 administration was interrupted, respiration worsened for all the patients. The worsening occurred in the majority of cases immediately after the interruption, for two patients (S1 and S6) after D270.

Figure 6

Effects of IGF1 treatment on bone density. (a): row values for bone density for each patient at D0 (empty histogram) and D365 (filled histogram). D0 (first day of treatment, before IGF administration), D90 (90 days after the first IGF1 administration), D180 (180 days after the first IGF administration, last day of IGF1 treatment), D270 (270 days after the first IGF administration), D365 (365 days after the first IGF administration). The dotted lines represent the start (D0) and the end (D180) of the treatment. Each patient is color-coded: S1: blue, S2: red, S3: green, S4: purple, and S6: orange. (b) Percentage of change between bone density at D365 versus bone density at D0. The majority of patients showed a ratio of 1, while for S3 and S6 the ratio was bigger than one showing an increase in bone mass after the treatment.

Figure 7

Effects of IGF1 treatment on brain activity. (a) Spectrum of frequencies (left) and EEG trace (right) for the site C4-T4 in all the treated subjects S1–S6 at D0 and D365. (b) Spectrum of frequencies (left) and EEG trace (right) for the site C4-T4 in all the untreated controls C1–C6 at D0 and D365. The color bar on the right shows intensity scale. (a) and (b): Frequencies spectrum Y-axis (blue plots) ranging between 0 and 15 Hz; X–axis ranging between 0 and 1700 sec. EEG traces Y-axis (white plots) ranging between −1.5 and +1.0 mV; X-axis ranging between 0 and 1700 sec. (c) Quantification of theta frequency (site C4-T4) in all the treated (T-red) and all the nontreated (NT-grey) RTT patients at D0 (non filled) and D365 (filled). There is a significant increase in theta frequency between the treated but not the untreated patients (Wilcoxon test).

Figure 8

Effects of IGF1 treatment on International Severity Scale (ISS). The graph reports the clinical evaluation of the parameters of the International Severity Scale (ISS). D0 (first day of treatment, before IGF administration), D90 (90 days after the first IGF1 administration), D180 (180 days after the first IGF administration, last day of IGF1 treatment), D270 (270 days after first IGF administration), and D365 (365 days after first IGF administration). The dotted lines represent the start (D0) and the end (D180) of the treatment. Each patient is color-coded: S1: blue, S2: red, S3: green, S4: purple, S5: cyan, and S6: orange. At each visit the patients were evaluated and the score for the ISS annotated. An increase in the score shows a worsening of the conditions, while a decrease in the ISS score represents an improvement. During IGF treatment (D0–D180), half of the patients showed an improvement in the ISS score. Between D180 and D270, the ISS score increased for all the patients with the exception of S5 and S6. At D365, S6 and S4 had an improved ISS, score, while S3 had the same score as that at D0. S5, S2, and S1 had a higher ISS score at D365 than at D0. The improvement in ISS score is not significant considering the entire cohort of patients.

Figure 9

IGF1 treatment is safe and tolerated by patients. Representation of the possible side effects of IGF1 in all of the treated patients: hypoglycemia (H-G), tonsillar hypertrophy (H-T-T), mammary hyperplasia (H-M), and seizures (S) at different times after IGF1 administration (D90, D180, D270, and D365) and correlation with IGF1 administration in all the treated patients. In the graph is reported the score for all the possible side effects in each subject and the correlation between the symptom and IGF1 administration (colorbar values from 1 to 5). The graph shows that only one patient—between D90 and D180—presented moderate mammary hyperplasia (score 3). This event is highly correlated to the IGF1 treatment (correlation score 5, values on the right) but disappeared spontaneously and without the administration of additional therapy. Two additional patients showed seizures during the treatment (score 1) but these are not associated with IGF1 treatment (correlation score 1).