CAMMS223.

Methods	CAMMS223 (primary reference) Multicentric, phase II, randomised clinical trial 49 centres in Europe and the United States Randomisation ratio 1:1:1, stratification to balance the study groups with regard to age (< 30 years or ≥ 30 years), gender and baseline EDSS scores (< 2.0 or ≥ 2.0) N = 334/available for analysis = 333 Treatment duration: 24 months Follow‐up duration: 36 months
Participants	Inclusion criteria Diagnosis of relapsing–remitting MS based on the McDonald criteria Onset of symptoms no more than 36 months before the time of screening; at least 2 clinical episodes during the previous 2 years; a score of 3 or less on the EDSS, which ranges from 0 to 10, with higher scores indicating greater disability; and one or more enhancing lesions, as seen on at least one of up to 4 monthly cranial magnetic resonance imaging (MRI) scans. Exclusion criteria Previous disease‐modifying treatments History of clinically significant autoimmunity Presence of serum antithyrotropin‐receptor antibodies
Interventions	Main interventions  Alemtuzumab 12 mg administered IV, once a day for 5 consecutive days at the first month and for 3 consecutive days at months 12 and 24 (the latter at the treating physicians' discretion if the CD4+ T‐cell count was ≥ 100 × 106 cells/L) (n = 113/available for analysis = 112) Alemtuzumab 24 mg administered IV, once a day for 5 consecutive days at the first month and for 3 consecutive days at months 12 and 24 (the latter at the treating physicians' discretion if the CD4+ T‐cell count was ≥ 100 × 106 cells/L) (n = 110/available for analysis = 110) Comparator Interferon beta‐1a (44 μg) administered subcutaneously 3 times weekly after dose escalation (n = 111/available for analysis = 111) All participants received 1 g of intravenous methylprednisolone for 3 days at baseline and at months 12 and 24, coinciding with infusion cycles as premedication for those receiving alemtuzumab. Some participants also received antihistamines or antipyretics at the investigators' discretion
Outcomes	Primary outcome measure Rate of participants with sustained accumulation of disability: Disability was assessed according to the ordinal EDSS score. A sustained accumulation of disability was defined as an increase of at least 1.5 points for participants with a baseline score of 0 and of at least 1.0 point for participants with a baseline score of 1.0 or more; all scores were confirmed twice during a 3‐ and 6‐month period. The onset of a sustained level of disability was timed to the first recorded increase in the EDSS score aside from relapse. Rate of relapse: Relapse was defined as new or worsening symptoms with an objective change in neurologic examination attributable to multiple sclerosis that lasted for at least 48 hours, that were present at normal body temperature, and that were preceded by at least 30 days of clinical stability. Secondary outcome measures Proportion of participants who did not have a relapse (proportion of participants with relapse‐free survival) Changes in lesion burden (as seen on T2‐weighted MRI) Brain volume (as measured by the Losseff method on T1‐weighted MRI8) Adverse effects, including the following measures: Thyroid function and levels of antithyrotropin receptor antibodies and lymphocyte subpopulations were measured quarterly at a central laboratory Serum‐binding antibodies against alemtuzumab were measured with the use of a validated enzyme‐linked immunosorbent assay (ELISA) at BioAnaLab Immune thrombocytopenia by single confirmed platelet count of fewer than 50,000 per microlitre without clumping or a platelet count of more than 50,000 but fewer than 100,000 per microlitre on at least 2 consecutive occasions during a period of at least 1 month, with normal haemoglobin, neutrophil and eosinophil counts; an absence of splenomegaly; and a normal peripheral‐blood smear (apart from thrombocytopenia). All adverse events with an onset up to 36 months were reported. In addition, all serious adverse events and autoimmune‐associated disorders occurring before 1 March 2008, were listed. A subsequent adverse event of Burkitt's lymphoma not associated with Epstein–Barr virus (EBV) was also included in this report.
Notes	The effectiveness of blinding was assessed at the end‐of‐study visit. Participants with an increased level of disability could be discontinued from the study. There was no active monitoring for progressive multifocal leukoencephalopathy. Preplanned interim analyses were performed when most participants had completed at least 1 year and 2 years with a prespecified alpha spending function. Disclosure of these results formed part of safety announcements by the sponsor in September 2005 and 2006. After the interim analyses, P values of less than 0.016 and 0.004 were considered to have statistical significance for the rates of sustained disability and relapse, respectively. In September 2005, the data and safety monitoring board recommended suspension of alemtuzumab treatments after receiving reports of 3 cases of immune thrombocytopenic purpura, including 1 death. All safety and efficacy assessments proceeded as planned and participants who were receiving interferon beta‐1a continued to receive the drug. At the time of dose suspension, only 2 eligible participants (1%) had not received the second cycle of alemtuzumab at month 12, whereas 155 participants (75%) were precluded from receiving the third cycle of alemtuzumab at month 24. More participants discontinued interferon beta‐1a than alemtuzumab, principally because of a lack of efficacy and adverse events, so that only 59% of the original group of participants receiving interferon beta‐1a completed the 36‐month study, as compared with 83% of participants receiving alemtuzumab. At the end of the study review, 90% and 91% of raters remained unaware of assignments to the group receiving interferon beta‐1a and the group receiving alemtuzumab, respectively. Funding: Genzyme
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Eligible participants were randomly assigned in a 1:1:1 with the use of the Pocock and Simon minimisation algorithm.
Allocation concealment (selection bias)	Unclear risk	No information available to allow a judgement
Blinding of participants and personnel (performance bias) All outcomes	High risk	Both study drugs have adverse effects that precluded masking of participants and treating clinicians to treatment assignment
Blinding of outcome EDSS assessment EDSS	Low risk	"EDSS scores were determined quarterly in a blinded fashion by a neurologist who also adjudicated possible relapses".
Blinding of outcome assessment (detection bias) All outcomes, except EDSS	Low risk	"MRI scans were performed annually and interpreted by a neuroradiologist who was unaware of assignments to study groups".
Blinding of safety outcome assessment	High risk	"Safety was assessed quarterly by the treating neurologist, who was aware of study‐group assignment".
Incomplete outcome data (attrition bias) All outcomes	Low risk	Number and reasons of withdrawals were similar in the interventions and control arms.
Selective reporting (reporting bias)	Low risk	—
Other bias	Low risk	—