A drug approved to prevent rejection of transplanted kidneys significantly reduced relapses of multiple sclerosis in a late stage-trial sponsored by Biogen Idec and AbbVie Inc, but serious infections and potential liver toxicity continued to cloud the drug's future.
The Phase III international study of the medicine, called daclizumab, involved more than 1,800 patients with relapsing-remitting multiple sclerosis, the most common form of MS, which can lead to disability and paralysis.
The companies disclosed partial results from the new trial on Monday.
The study, called DECIDE, tested monthly injections of daclizumab against weekly injections of Biogen's blockbuster Avonex (interferon beta-1a) treatment for MS.
Patients taking daclizumab, which is meant to tame the immune system by blocking a protein called the CD25 receptor, had 45 percent fewer annual relapses than those receiving Avonex. In addition, patients taking daclizumab had 54 percent fewer new or enlarging brain and spinal lesions at week 96 of the study, compared to those taking Avonex; those results met a secondary goal of the study.
The overall incidence of side effects was similar in both patient groups. But there was a two-fold higher incidence of serious infections among those taking daclizumab, at 4 percent, as well as a two-fold higher incidence of elevated liver enzymes - a potential marker for liver toxicity.
Daclizumab would be a new approach to treating MS, if it is approved for the condition.
Alex Arfaei, an analyst with BMO Capital Markets, said the decline in annual relapses seen with daclizumab was a bit less impressive than the reductions of 52 percent, versus Avonex, achieved in earlier trials by the oral medication Gilenya, which is made by Novartis AG. Gilenya had sales of $1.9 billion last year.
"Our first impression is that these results are good enough for (daclizumab) to be competitive" with Gilenya and other oral treatments, Arfaei said in a research note.
He predicted the Biogen/AbbVie drug could be introduced in 2016 and conservatively generate U.S. sales of $256 million by 2018.
Biogen and AbbVie said they would discuss with health regulators the timing for potential marketing applications for daclizumab.
Swiss drugmaker Roche Holding AG introduced daclizumab in 1997 to prevent rejection of transplanted kidneys, under the brand name Zenapax. It stopped selling the drug in 2009 due to poor sales and the availability of newer treatments.
Multiple sclerosis is believed to be caused by overactive immune system cells, called t-cells, that attack and destroy the protective covering of nerves.
Biogen shares were up 0.8 percent in morning trading on the Nasdaq. AbbVie shares slipped 0.3 percent on the New York Stock Exchange.
(Reporting by Ransdell Pierson; Editing by Nick Zieminski and Leslie Adler)