Inclusion Criteria:

General

1. sign written informed consent prior to participating in the study

2. 25 through 65 years of age inclusive

3. females of childbearing potential must:

- have a negative pregnancy test at Baseline (prior to randomization) and

- use simultaneously two forms of effective contraception during the treatment and
3-months after discontinuation of study medication

Primary Progressive Multiple sclerosis.

1. diagnosis of primary progressive multiple sclerosis (according to the 2005 Revised
McDonald criteria):

2. time since first reported symptoms between 2 and 10 years

3. evidence of clinical disability progression in the 2 years prior to Screening

4. disability status at Screening

- EDSS score of 3.5-6.0 inclusive

- pyramidal functional system score of 2 or more

- 25'TWT less than 30 seconds

Exclusion Criteria:

PPMS specific:

- History of relapses/attacks

- Progressive neurological disorder other than PPMS

- Pure cerebellar syndrome or pure visual progressive syndrome or pure

- cognitive progressive syndrome

- Presence of spinal cord compression at screening MRI

- Relevant history of vitamin B12 deficit

- Evidence of syphilis or borreliosis at Screening

Cardiovascular conditions:

- Myocardial infarction within the past 6 months or current unstable ischemic heart
disease

- History of angina pectoris due to coronary spasm or history of Raynaud's phenomenon

- Severe cardiac failure or cardiac arrest

- History of symptomatic bradycardia

- Resting pulse <55 bpm pre-dose

- History of sick sinus syndrome or sino-atrial heart block

- History or presence of second and third degree AV block or an increase QT interval
(QTc>440 ms)

- Arrythmia requiring treatment with class III antiarrythmic drugs

- History of positive tilt test from workout of vasovagal syncope

- Hypertension, not controlled with medication

Pulmonary:

- Severe respiratory disease or pulmonary fibrosis

- TB

- Abnormal X-ray, suggestive of active pulmonary disease

- Abnormal PFT: <70% of predicted for FEV1 and FVC; <60% for DLCO

- Patients receiving chronic (daily) therapies for asthma

Hepatic:

- Known history of alcohol abuse, chronic liver or biliary disease

- Total or conjugated Brb >ULN, unless in context of Gilbert's syndrome

- AP >1.5xULN; ALT/AST >2xULN; GGT>3xULN

Other:

- History of chronic disease of the immune system other than MS

- Malignancy (other than successfully treated SCC or BCC)

- Diabetes Mellitus

- Macular Edema present at screening

- HIV, Hepatitis C or B, other active infection

- History of total lymphoid irradiation or bone marrow transplantation

- Serum creatinine >1.7 mg/dl

- WBC <3500 cells/mm3

- Lymphocyte count <800 cells/mm3

- History of substance abuse or any other factor that may interfere with subject
ability to cooperate and comply with the study procedures

- Unable to undergo MRI scans

- Participation in any therapeutical clinical research study in the 6 months prior to
randomization

- Pregnant or lactating women

- Drugs requiring wash-out period:

3 months:

- Systemic corticosteroids or ACTH

- INF-beta

6 months:

- Immunosuppressive medication

- Immunoglobulins

- Monoclonal antibodies

- Drugs that exclude participation in the study:

- Cladribine

- Cyclophosphamide

- Mitoxantrone (except: patients who received a cumulative dose of no more than 60mg/m2
more than 5 years ago could enter the study)

Other protocol-defined inclusion/exclusion criteria may apply.