Please assess the completion status of the following clinical trial:

Trial Title: Natalizumab De-escalation to Interferon-beta-1b in Patients With Relapsing-remitting Multiple Sclerosis

Study Design Characteristics:
- Allocation: None
- Intervention Model: SINGLE_GROUP
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: NONE
- Phase: PHASE4
- Number of Arms: 1.0

Eligibility Criteria:
Inclusion Criteria:~* Female or male patients with relapsing-remitting forms of multiple sclerosis (according to McDonald's criteria);~* Age between 18 and 70 years;~* Natalizumab-treatment for at least 12 months following the current Swiss guidelines for treatment initiation;~* Treated with a disease-modifying therapy other than interferon beta-1b for at least 12 months before natalizumab was initiated;~* Never treated with interferon beta-1b;~* Eligible patients are clinically stable (free from relapses and 6-month confirmed disability progression for at least 6 months) while on natalizumab-treatment and do not show any Gd-enhancement on their last MRI performed while on Tysabri;~* In eligible patients MRI were performed in the past as following~  * 6-18 months prior to natalizumab-treatment~ * at natalizumab start~ * 12 months after natalizumab initiation;~* Good records with regard to clinical disease activity (relapse rate, EDSS progression) in the year prior to natalizumab and during natalizumab;~* Patients who decide to stop natalizumab treatment after a careful benefit/risk assessment. Risk for PML increases with duration of natalizumab exposure, pre-treatment with an immunosuppressant agent or serological status of anti-JC-virus positivity;~* Patients, who in context with cessation of natalizumab have decided, after a careful benefit/risk assessment, to continue treatment of their MS with Interferon beta-1b;~* Women of potential childbearing with active contraceptive methods;~* Patients who are willing to undergo study procedures;~* Patients who are willing to undergo MRI;~* Patients who are willing and able to sign informed consent.~Exclusion Criteria:~* Patients who have previously entered this study;~* Natalizumab-treatment for less than 12 months following the current Swiss guidelines for treatment initiation;~* Prior treatment with interferon beta-1b (ever interferon beta-1b);~* Sign of clinical disease activity within the 6 months;~* One or more relapses and/or 6-month confirmed disability progression during the 6 months prior to the study;~* Secondary progressive MS;~* Primary progressive MS;~* Pregnancy - Serum pregnancy test at screening visit positive- or breast feeding;~* Uncontrolled, clinically significant heart diseases, such as arrhythmias, angina, or uncompensated congestive heart failure;~* History of severe depression or attempted suicide or current suicidal ideation;~* Medical or psychiatric conditions that compromise the ability to give informed consent, to comply with the protocol, or to complete the study;~* Uncontrolled seizure disorder;~* Myopathy or clinically significant liver disease;~* Inability, in the opinion of the principal investigator or staff, to comply with protocol requirements for the duration of the study;~* Known hypersensitivity to interferon-beta or other human proteins including albumin;~* Any contraindication for MRI or contrast administration;~* A history of drug abuse in the 6 months prior to screening;~* Treatment with any of the following in the 30 days before day 1: systemic corticosteroids, ACTH, or other investigational drugs;~* Participation in any other study involving investigational or marketed products, concomitantly or within 30 days prior to entry in the study;~* Current participation on other clinical trials;~* Treatment with drugs which might interfere with the evaluation of study drugs during the study protocol such as immunomodulants, immunosuppressives other than interferon beta-1b;~* Likelihood of requiring treatment during the study period with drugs not permitted by the study protocol such as immunomodulants, immunosuppressives other than interferon beta-1b.

- Gender: ALL
- Minimum Age: 18 Years
- Maximum Age: 70 Years
- Healthy Volunteers: f

Study Arms:
- Interferon beta-1b (Type: EXPERIMENTAL): Interferon beta-1b 250 mcg s.c. every other day

Based on this trial design, predict the completion outcome and termination type (if applicable).