Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1.        Pharmacodynamic properties
Pharmacotherapeutic group: Antineoplastic and immunomodulating agents, Other Immunostimulants
ATC code: L03AX13
Mechanism of action
The mechanism(s) by which glatiramer acetate exerts its effects in relapsing forms ofMS is not fully elucidated but it is presumed to involve modulation of immune processes.
Studies in animals and in MS patients suggest glatiramer acetate-acts on innate immune cells, including monocytes, dendritic cells and B cells, which in turn modulate adaptive functions of B and T cells inducing anti-inflammatory and regulatory cytokine secretion. Whether the therapeutic effect is mediated by the cellular effects described above is not known because the pathophysiology of MS is only partially understood.


Clinical efficacy and safety
RRMS:
A total of 269 patients have been treated with Copaxone in three controlled trials. The first was a two-year study involving 50 patients (Copaxone n=25, placebo n=25) who were diagnosed with relapsing-remitting MS by the then-applicable standard criteria, and who had at least two attacks of neurological dysfunction (exacerbations) during the preceding two years. The second study applied the same inclusion criteria and included 251 patients treated for up to 35 months (Copaxone n=125, placebo n=126). The third study was a nine-month study involving 239 patients (Copaxone n=119, placebo n=120) where inclusion criteria were similar to those in
the first and second studies with the additional criterion that patients had to have at least one gadolinium-enhancing lesion on the screening MRI.
In clinical trials in MS patients receiving Copaxone, a significant reduction in the number of relapses, compared with placebo, was seen.
In the largest controlled study, the relapse rate was reduced by 32% from 1.98 under placebo to 1.34 under glatiramer acetate.
Exposure data are available for up to twelve years in 103 patients treated with Copaxone.
Copaxone has also demonstrated beneficial effects over placebo on MRI parameters relevant to relapsing-remitting MS.
Copaxone 20 mg/mL: In the controlled study 9001/9001E, which enrolled 251 patients, who were followed for up to 35 months (including a blinded phase extension 9001E of the 9001 study), the cumulative percentage of patients who developed 3-month confirmed disability progression was 29.4% for placebo and 23.2% for Copaxone-treated patients (p=0.199).
There is no evidence that Copaxone treatment has an effect on relapse duration or severity.
There is currently no evidence for the use of Copaxone in patients with primary or secondary progressive disease.

Single clinical event suggestive of MS:
One placebo-controlled study involving 481 patients (Copaxone n=243, placebo n=238) was performed in patients with a well-defined, single, unifocal neurological manifestation and MRI features highly suggestive of MS (at least two cerebral lesions on the T2-weighted MRI above 6 mm diameter). Any disease other than MS that could better explain signs and symptoms of the patient had to be excluded. The placebo-controlled period was followed by an open label treatment: Patients who either presented with MS symptoms or were asymptomatic for three years, whichever came first, were assigned to active drug treatment in an open-label phase for an additional period of two years, not exceeding a maximal total treatment duration of 5 years.
Of the 243 patients initially randomized to Copaxone, 198 continued Copaxone treatment in the open-label phase. Of the 238 patients initially randomized to placebo, 211 switched to Copaxone treatment in the open-label phase.
During the placebo-controlled period of up to three years, Copaxone delayed the progression from the first clinical event to clinically definite multiple sclerosis (CDMS) according to Poser criteria in a statistically significant and clinically meaningful manner, corresponding to a risk reduction of 45% (Hazard Ratio = 0.55; 95% CI [0.40; 0.77], p-value=0.0005). The proportion of patients who converted to CDMS was 43% for the placebo group and 25% in the Copaxone group.
The favourable effect of treatment with Copaxone over placebo was also demonstrated in two secondary MRI endpoints, i.e. number of new T2 lesions and T2 lesion volume.
Post-hoc subgroup analyses were performed in patients with various baseline characteristics to identify a population at high risk to develop the second attack. For subjects with baseline MRI with at least one T1 Gd-enhancing lesion and 9 or more T2 lesions, conversion to CDMS was evident for 50% of the placebo subjects vs. 28% of the Copaxone subjects in 2.4 years. For subjects with 9 or more T2 lesions at baseline, conversion to CDMS was evident for 45% of the placebo subjects vs. 26% on Copaxone in 2.4 years. However, the impact of early treatment with Copaxone on the long term evolution of the disease is unknown even in these high-risk subgroups as the study was mainly designed to assess the time to the second event. In any case, treatment should only be considered for patients classified at high risk.
The effect shown in the placebo-controlled phase was sustained in the long-term follow-up period of up to 5 years. The time progression from the first clinical event to CDMS was prolonged with earlier Copaxone treatment as compared to delayed treatment, reflecting a 41% risk reduction with earlier versus later treatment (Hazard Ratio = 0.59; 95% CI [0.44; 0.80], p- value=0.0005). The proportion of subjects in the Delayed Start group who progressed was higher (49.6%) compared to those in the Early Start group (32.9%).
A consistent effect in favour of early treatment over delayed treatment across time was shown for the annualized number of lesions over the entire study period in new T1 Gd-enhancing lesions (reduced by 54%; p<0.0001), new T2 lesions (reduced by 42%; p<0.0001) and new T1 hypointense lesions (reduced by 52%; p<0.0001). An effect in reductions in favour of early versus delayed treatment was also observed for the total number of new T1 Gd-enhancing lesions (reduced by 46%; p=0.001), T1 Gd-enhancing lesion volume (a mean difference of -0.06 ml; p<0.001), as well as the total number of new T1 hypointense lesions (reduced by 46%; p<0.001) measured over the entire study period.
No appreciable differences between the Early Start and Delayed Start cohorts were observed for either hypointense T1 lesion volume or brain atrophy over 5 years. However, analysis of brain atrophy at last observed value (adjusted to treatment exposure) showed a reduction in favour of early treatment with GA (the mean difference of percent change in brain volume was 0.28%; p=0.0209).

Pharmacokinetic Properties

5.2.        Pharmacokinetic properties
Pharmacokinetic studies in patients have not been performed. In vitro data and limited data from healthy volunteers indicate that with subcutaneous administration of glatiramer acetate, the active substance is readily absorbed and that a large part of the dose is rapidly degraded to smaller fragments already in subcutaneous tissue.