repeated subcutaneous injections of a monoclonal antibody against the p40 subunit of interleukins 12 and 23 ustekinumab were used to treat patients with relapsing remitting multiple sclerosis rrms to assess the drug s safety efficacy and pharmacokinetics in this phase ii multicentre randomised double blind placebo controlled study 249 patients with rrms aged 18 65 years were eligible to be assigned equally by a central randomisation procedure based on study site and presence or absence of gadolinium enhancing t1 weighted lesions at baseline to one of five groups that received placebo or four different ustekinumab dosages at weeks 0 1 2 3 7 11 15 and 19 ustekinumab doses were 27 mg 90 mg q8w 90 mg or 180 mg the 90 mg q8w dosage group received placebo substitute at weeks 7 and 15 the primary endpoint was the cumulative number of new gadolinium enhancing t1 weighted lesions on serial cranial mri through week 23 patients were followed up through week 37 analysis was by intention to treat this trial is registered with clinicaltrials gov number nct00207727 from august 2004 to december 2006 249 patients underwent randomisation 49 for placebo 50 for each ustekinumab group ustekinumab treatment did not show a significant reduction in the primary endpoint for any dosage groups versus placebo at week 37 adverse events occurred in 38 78 placebo treated patients and 170 85 ustekinumab treated patients with infections most commonly reported serious adverse events occurred in one 2 placebo treated patient and six 3 ustekinumab treated patients malignant diseases were reported in two patients shortly after the initiation of ustekinumab treatment both patients were withdrawn from the trial and given appropriate treatment which resulted in complete remission no serious infections cardiovascular events or exacerbation of demyelinating events occurred a dose dependent increase in serum concentrations of ustekinumab was recorded ustekinumab is generally well tolerated but does not show efficacy in reducing the cumulative number of gadolinium enhancing t1 weighted lesions in multiple sclerosis.