ANCA Associated Vasculitis Subtypes: Response [Response to Letter].

Dear Editor

Many thanks for the opportunity to respond to the interesting letter to the Editor from Merkel, Jayne, and Bekker, with regard to our publication “ANCA Associated Vasculitis Subtypes: Recent Insights and Future Perspectives”.1

In the management section of our review article, we highlighted some examples of where “personalized” treatment could be explored further in trials of ANCA associated vasculitis.

Our main evidence in terms of the influence of serotype on disease outcomes was in relation to the RAVE study, ie, PR3-ANCA cases responding better to Rituximab than cyclophosphamide in terms of long-term outcomes.2

We did, however, also reference the ADVOCATE study and appreciate that, in doing so, we could have been clearer about our meaning. The comment about MPO-ANCA cases within ADVOCATE was based on 12-month outcomes for sustained remission, in which there were numerically more sustained remissions in the avacopan-treated MPO group versus the PR3 group and both prednisolone-treated groups.3 We intended to highlight that numerical differences – even if not statistically significant or powered – may warrant future work into the effect of ANCA subtype on response to treatment.

However, we completely appreciate Merkel et al highlighting the important point that the ADVOCATE trial was not primarily powered to assess differences in ANCA subtype and background immunosuppression and, therefore, the current data does not currently indicate a personalized medicine approach in relation to avacopan.

We hope this helps to clarify things and look forward to new trials in the future where these interesting topics can be explored in greater depth.