Biosimilar therapy shows similar 6-month remission rates in AAV
Canadian study found no significant differences in short-term outcomes or safety
Written by |
Six-month remission rates with biosimilar versions of rituximab were similar to those seen with the original therapy among adults with the two most common types of ANCA-associated vasculitis (AAV), according to a real-world study in Canada.
Data also showed no significant differences in serious adverse events or AAV-related damage between the original therapy and its biosimilars. Rituximab, sold under the brand name Rituxan among others, is approved for people with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), the two most common types of AAV.
“This study found no significant differences in six-month outcomes between the rituximab originator and biosimilars for induction of [remission in] GPA and MPA, with no concerning early signals in those initiating maintenance [treatment] or switching from the originator to a biosimilar,” the researchers wrote. “The present study provides unique real-world evidence of the rituximab originator compared to the biosimilar in AAV.”
Study compares original and biosimilar rituximab in AAV
The study, “Biosimilar Rituximab in ANCA-Associated Vasculitis Compared to the Originator: A Multicenter Cohort Study,” was published in the journal ACR Open Rheumatology.
AAV is a group of rare autoimmune disorders marked by inflammation and damage in small blood vessels. This process is associated with ANCAs, self-reactive antibodies that abnormally activate certain immune cells, prompting them to attack blood vessel walls. The kidneys, lungs, and upper airways are frequently affected.
Rituximab is administered directly into the bloodstream and works by depleting B-cells, a type of immune cell involved in antibody production.
It may be used to induce AAV remission, when there are few or no signs of active disease, or as maintenance treatment to help prevent relapses, when symptoms suddenly worsen or new symptoms develop.
Several biosimilar versions of rituximab are available around the world. Biosimilars are versions of biologic therapies that are highly similar to the original medication, with no clinically meaningful differences in safety or effectiveness. They are often sold at lower prices.
In Canada, some provincial public payors began requiring biosimilars for patients starting rituximab treatment in 2020. In 2021, some provinces also began requiring patients already receiving the original therapy to switch to a biosimilar.
Although controlled clinical trials demonstrated comparable safety and efficacy of some rituximab biosimilars in people with certain blood cancers and autoimmune diseases, “no trials were conducted in AAV, which exhibits different disease mechanisms and adverse event patterns,” the researchers wrote.
Real-world Canadian study tracks outcomes across treatment groups
To address this, researchers conducted a real-world study called BRAVO (NCT05716334), which included 144 adults with GPA and 63 with MPA who were treated with rituximab between 2018 and 2023 at nine Canadian centers.
Most participants (63.8%) were starting rituximab as induction treatment: 58 received the original medication and 74 received a biosimilar. More than one-quarter (28.5%) were starting rituximab as maintenance treatment: 23 received the original medication and 36 received a biosimilar.
The remaining 16 participants (7.7%) switched to a biosimilar after receiving maintenance treatment with the original rituximab for a mean of 2.2 years. All but one of these switches were required by an insurer or other payor. The most commonly used biosimilar, given to more than 85% of participants who received a biosimilar, was Ruxience (rituximab-pvvr).
Researchers focused on a prespecified six-month remission outcome, defined as a Birmingham Vasculitis Activity Score of zero. The analysis included 197 participants.
Among participants receiving induction treatment, six-month remission rates were similar between the original rituximab and biosimilar groups, at 96% and 90%, respectively. Two participants in the biosimilar group died within one month of starting induction treatment, before achieving remission. When they were excluded from the calculation, the biosimilar remission rate was 93%.
One minor relapse occurred in each induction group, both in participants with GPA. Changes in AAV-related organ damage, as assessed with the validated Vasculitis Damage Index, also did not differ significantly between the original rituximab and biosimilar groups.
One exploratory analysis found a significantly higher three-month remission rate with original rituximab than with biosimilars, 94% vs. 79%. The difference remained statistically significant after accounting for age. The finding raised the possibility that remission occurred more slowly with biosimilars, but the researchers cautioned that further study is needed before firm conclusions can be drawn.
Maintenance and switch groups remain in remission at 6 months
Maintenance treatment data showed that all 22 evaluable participants receiving original rituximab and all 33 receiving biosimilars were in remission at six months. One minor relapse occurred in the original rituximab group, while no relapses occurred with biosimilars. All 16 participants who switched to a biosimilar also remained in remission at six months.
Serious adverse events, including infections, were reported in 21 participants, with no significant differences in rates between the original and biosimilar groups.
In addition to the two participants who died in the biosimilar induction group — one from active AAV with bleeding in the lungs and one from COVID-19 pneumonia — one participant in the switch group died from pneumonia.
The team noted several study limitations, including its observational design, small maintenance and switch groups, and follow-up limited to six months.
“Although 24-month [2-year] follow-up will optimally evaluate relapses during maintenance, these real-world data support continued biosimilar rituximab use in AAV, and should reassure patients, providers, and policymakers,” the researchers wrote.
Leave a comment
Fill in the required fields to post. Your email address will not be published.