The condition attacks the joints
A drug reserved for advanced rheumatoid arthritis (RA) could save thousands of people with early stage disease from disability, say researchers.
Trials show rituximab, marketed as MabThera, almost completely halts the deterioration of the joints in people showing the first signs of the disease.
In Britain alone nearly 18,000 people are diagnosed with RA each year.
The findings presented at the EULAR conference could lead to a shift in recommended treatment, experts said.
The National Institute for Health and Clinical Excellence currently says rituximab should be used only if other arthritis drugs called TNF treatments have failed.
But the latest study on 755 patients shows the drug, when used with the gold standard treatment for early RA methotrexate for a year, not only reduces symptoms but slows joint damage to almost a complete stop if used early enough.
About 70% of patients treated within six months of their first symptoms developed no joint damage over the first 12 months of therapy, and after only six months of treatment joint damaged stopped almost completely.
In comparison, many patients on methotrexate alone will develop continuous joint damage.
Although expensive, a course of rituximab treatment costs nearly £3,500, the therapy could ultimately save the NHS money, say campaigners.
The direct and indirect costs of RA in the UK are estimated to be £3.8-£4.75 billion every year, much of this is due to people becoming too debilitated to work.
And a course of anti-TNF therapy costs around £12,000.
Leading rheumatologist Professor John Isaacs, of the Institute of Cellular Medicine at Newcastle University, said: "The emphasis should be on the early stage of disease. When patients first develop the disease there is no joint damage and the aim is to prevent that happening. That's essentially what this combination is doing.
"There are many trials going on around the world now looking at these sorts of drugs very early...and the results do look very good."
Most patients with early disease are started on anti-inflammatory pain killers like ibuprofen
The next step is disease-modifying drugs like methotrexate to slow down progression and delay joint damage
Newer biologics like anti-TNF drugs are tried
When anti-TNF therapy fails - about 40% of cases - drugs like rituximab can be offered
He said ultimately it would be up to NICE to decide if rituximab should now be used earlier. However, the drug is not yet licensed for use in early RA.
Rituximab works by targeting the immune system which causes the damage in RA.
Ailsa Bosworth, chief executive of the National Rheumatoid Arthritis Society, said: "The findings are very exciting.
"Hopefully this can form part of the evidence base we need to convince NICE that these drugs should be used earlier in RA.
"At the moment we are not allowed to use this at early stage disease when patients would benefit the most and instead have to wait until they are sicker.
"These drugs are expensive and we understand that they have to be used judiciously. But we could look at targeting therapy to patients with the most aggressive disease."
This would equate to about 10% of the half a million people with RA, she said.
A spokeswoman for the Arthritis Research Campaign, the charity that pioneered anti-TNF therapy, said it was important to target patients whose disease was likely to become severe.
"Research is on-going to establish which patients will benefit most from rituximab and anti-TNF therapy early," she said.
A spokeswoman from NICE said rituximab would need to get its licence and then be referred to them by the Department of Health before they could consider it for use in early RA.