In a new study comparing Rituxan (rituximab) and azathioprine for the treatment of ANCA-associated vasculitis (AAV), rituximab was found to be a cost-effective option, even though it is the more expensive treatment.
The study, “Cost-effectiveness of rituximab versus azathioprine for maintenance treatment in antineutrophil cytoplasmic antibody-associated vasculitis,” was published in the journal Clinical and Experimental Rheumatology.
Rituxan is a monoclonal antibody that targets the CD20 molecule, allowing it to “turn off” certain types of immune cells, most notably B cells, that are aberrantly active in autoimmune diseases such as AAV. Azathioprine is a drug with a similar therapeutic goal: it decreases activity in the immune system.
Both modalities can be used to treat AAV. Previous research that compared them head-to-head found that Rituxan was the most effective treatment, with more patients experiencing sustained remission.
However, as is often the case with biologics (therapies that need to be produced in part by living cells, such as antibodies), Rituxan is more expensive than azathioprine. Thus, it’s possible that even though it might be less effective overall, azathioprine could theoretically still be the more practical choice for AAV patients in terms of strict cost/benefit balance.
To find out, researchers analyzed data from the previous MAINRITSAN Phase 3 clinical trial (NCT00748644) that compared the efficacy of the two treatments, and led to the approval of Rituxan as a remission maintenance treatment for two AAV subtypes — granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
This trial included 115 people with AAV who were treated at 54 centers in France between 2008 and 2012.
Half were given Rituxan (500 milligrams administered intravenously on day 0, day 14, and months 6, 12, and 18 of treatment); the other half were treated with azathioprine (taken orally at 2 milligrams per kilogram of body weight for the first year, then at decreasing doses for the next 10 months).
Investigators used this data, combined with data from French Social Health Insurance, which covers 100% of AAV costs, to estimate patient costs. They also estimated patients’ quality of life based on the number of relapses a patient experienced, as well as the results of a short questionnaire given to participants at the start and then every three months of the 28-month study.
As expected, azathioprine was a less costly treatment than Rituxan, by €3,170 (~$3,560) on average. This was mostly due to the increased cost of Rituxan itself and of administering Rituxan, which together accounted for 63% of the costs incurred by those given this treatment.
However, patients on azathioprine were more likely to experience relapses, as previously mentioned. This was not without its own costs; relapses accounted for 27% of the costs incurred by patients on azathioprine and for just 5% of costs incurred by those on Rituxan.
Additionally, Rituxan resulted in a comparatively greater gain in quality of life, as calculated by increased quality-adjusted life years (QALYs). Specifically, there was an average gain of 0.084 QALYs in the Rituxan compared to the azathioprine group over the 28 months of the study — a small but significant gain, and one that might be expected to increase over a longer study period.
The researchers also noted that the price of Rituxan might be expected to decrease by as much as 30% once biosimilars — the biologics equivalent of generic drugs — are on the market, which would make the treatment even more economical.
“These findings, driven by lower rates of relapses and corresponding higher quality of life in [Rituxan]-treated patients, support the use of RTX for maintenance, over previously standard, conventional immunosuppressants such as [azathioprine],” the researchers concluded in their paper.