Clonal haematopoiesis of indeterminate potential and relapses in patients with GCA

GCA is the most common vasculitis after 50 years of age, responsive to steroids with frequent relapses. Our objective was to evaluate clonal haematopoiesis of indeterminate potential (CHIP) as a risk factor for relapse in GCA.

We prospectively analysed CHIP in a monocentric cohort of recently diagnosed GCA patients. CHIP was defined as a variant in a gene implicated in myeloid malignancies with allele frequency >2% detected in peripheral blood mononuclear cells by next-generation sequencing. Relapses were defined as GCA related signs or symptoms and/or inflammatory syndrome attributable to GCA after remission induction. The primary outcome was relapse occurring within 12 months of GCA induction treatment.

We included 40 patients with 20 women (50%) of median age 73 years [67-80]. At diagnosis, 16 (40%) patients had ophthalmic involvement and 23 (57%) patients had large vessel involvement. CHIP was detected in 18 (45%) patients. During a median follow-up of 26 [14-45] months, 17 (42%) patients relapsed at 12 months. In multivariate analysis, baseline factors independently associated with GCA relapse at month 12 were ophthalmologic involvement at diagnosis (OR 4.02, 95% CI [1.19-13.56], P < 0.025) and the presence of CHIP (OR 9.94, 95% CI [2.98-33.17], P = 0.0002).

The presence of CHIP is associated with GCA relapses in this exploratory cohort. Further studies are needed to confirm these findings.