Which ANCA vasculitis patients are better candidates for cyclophosphamide rather than rituximab?

Both can be used for induction in GPA/MPA vasculitis. I would use rituximab (RTX) if the patient has previously been treated with cyclophosphamide (CYC) and developed a relapse/flare and in patients who are young and with fertility concerns. In GPA/MPA, I tend to use RTX most of the time for induction but would use CYC in patients who are intubated with alveolar hemorrhage or rapidly progressive renal involvement/ESRD especially because the time to onset for RTX can be more delayed (and in the extremely sick patients in RITUXVAS trial, the patients also received 2 doses of IV CYC).

For EGPA, CYC should be used especially if there's cardiac involvement or high Five-Factor Score (worse mortality). If ANCA positive, severe disease or other reas...

Another controversial issue! I have not seen convincing evidence that the effect of cyclophosphamide in ANCA-associated vasculitis is “faster” than the effect of rituximab; there are data from RAVE of equal time to remission for these two treatments. Remember that treatment trials of AAV (until ADVOCATE) included substantial initial courses of glucocorticoids for all treatment groups, obscuring the individual effect of other drugs. Additionally, there is no obvious reason to consider cyclophosphamide superior to rituximab for patients with diffuse alveolar hemorrhage or advanced renal failure. The pathophysiology of these manifestations are almost certainly the same for moderate-severe vs. severe disease (often only a matter of days between...