Belgium's Ablynx has presented impressive data on its rheumatoid arthritis treatment ozoralizumab, comparing the drug favourably with Abbott Laboratories' blockbuster Humira.

The firm has announced that ATN-103 (ozoralizumab), a TNF-alpha targeting nanobody, showed excellent safety and efficacy results in the 48-week open-label extension study of the worldwide and Japanese Phase II trials in the treatment of patients with RA who have an insufficient response to methotrexate alone.

Some 266 patients from the previous two Phase II studies rolled-over into the extension study (which was fully funded by Ablynx' former partner Pfizer) were treated with ozoralizumab by a subcutaneous injection every four weeks. The most common adverse events associated with ozoralizumab treatment were infections and of these, only three per 100 patient years were serious, which is comparable to those seen with other TNF-alpha drugs.

Only 2.6% of patients tested positive for neutralising anti-drug antibodies (nADAs) at any time during the 48 week-study and all of them completed the trial, with 57% of these patients achieving DAS28 (a much-used disease activity measure) remission. Moreover, the Ghent-based firm said, only 0.75% of patients remained positive for nADAs at the end of the treatment period.

Ablynx noted that Humira (adalimumab) states on its label that it may produce neutralising antibodies in 1-12% of patients within one year of treatment, "though recent data suggest that this number may be considerably higher and up to 35%". In addition, the label states that formation of anti-adalimumab antibodies is associated with reduced efficacy, "which is confirmed in a recent publication to result in a diminished treatment response (only 4% of patients with nADAs achieved DAS28 remission), hence the need to switch to another drug regimen over time".

With a mean improvement of 3.11 in the overall DAS28 score, 38% of patients achieved the criteria for disease remission (ie no signs of disease activity), which Ablynx noted was the ultimate treatment goal. Already at week 12, patients achieved a 70% and 62% reduction in swollen and tender joint counts respectively, with 61% of all patients showing at least one measure of no or low disease activity.

Last November, Pfizer returned the rights to ozoralizumab but Ablynx chief executive Edwin Moses said that "we always believed in this programme and now the data from this long-term study have even positively surprised us". He argues that "we now have extensive efficacy data that are potentially as good, if not better, than other commercially available anti-TNFa products - and this is a $24 billion market".

In terms of immunogenicity, the data shows "an unexpected and potentially major advantage over Humira…and any of its biosimilar competitors that may be launched in the future", Dr Moses added. He concluded by saying "we now have the components of a much stronger and differentiating licensing package than we had previously".