Rituximab is a medication that works by attaching to a protein called CD20 on certain immune cells (B‑cells). By binding to these cells, it helps reduce the activity of the immune system, which can prevent the blood vessels from being attacked in diseases like granulomatosis with polyangiitis and microscopic polyangiitis. In this trial it is used as the standard treatment (comparator) to see how well a new approach works.

Truxima is a medicine that contains the same active ingredient as rituximab. It is given through an IV infusion and works in the same way—by targeting B‑cells to calm down the immune system. In the study it is the test product, meaning the researchers are comparing its effects to the standard rituximab treatment.

Prednisone is a steroid taken by mouth that helps lower inflammation and suppresses the immune response. It is often used to control symptoms when blood vessel inflammation flares up. In this trial it serves as a comparator medication, providing a reference for how well the rituximab‑based strategies keep patients in remission.

Granulomatosis with polyangiitis – It is a rare autoimmune disease that causes inflammation of small blood vessels, especially in the nose, lungs, and kidneys. Early signs often include sinus problems, cough, and blood in the urine. As the inflammation continues, it can narrow the vessels and damage the affected organs. Symptoms may flare up and then become quieter over time. The condition is chronic and requires regular monitoring.
Microscopic polyangiitis – This is a rare autoimmune disorder that inflames small blood vessels without forming granulomas, most often affecting the lungs and kidneys. It usually starts with fatigue, muscle aches, and skin spots before kidney problems appear. Ongoing inflammation can lead to worsening kidney function if it progresses. The disease may have periods of increased activity followed by quieter phases. It is a long‑term condition that needs continual observation.