a 73-year-old woman
IgA nephropathy with cellular crescents, in a patient with polycythemia vera carrying a JAK2 V617F mutation
Doctors avoided steroids at first because steroids could worsen her blood cancer. Instead they started a JAK inhibitor called ruxolitinib. Over the next year her urine protein went down and her serum creatinine held steady. Later she took a two-year tapering course of corticosteroids and reached clinical remission. The authors say this is the first reported case of IgA nephropathy improving after JAK inhibitor treatment.
In one older woman whose IgA nephropathy came alongside a blood cancer called polycythemia vera, the JAK inhibitor ruxolitinib was tied to less protein in the urine and steady kidney function before steroids were ever used.
- Her kidney problem (blood in urine, protein in urine, and falling kidney function) was confirmed by biopsy as IgA nephropathy with cellular crescents, a more active form.
- Doctors held off on steroids at first because steroids could make her polycythemia vera worse, so they started ruxolitinib instead.
- Over the next year her urine protein went down and her serum creatinine held steady, which the authors read as improving IgA nephropathy activity.
- A later two-year tapering course of corticosteroids brought clinical remission.
- The authors say this is the first reported case of IgA nephropathy improving after JAK inhibitor treatment in a patient with polycythemia vera.
Why it might work
The authors think the JAK inhibitor may help in two ways. First, blocking JAK signaling can lower IL-6 and IL-11, which drive platelet-derived growth factor. Less of that growth factor could mean less overgrowth of the mesangial cells in the kidney filter. Second, the drug may calm the abnormal blood-cell production that makes faulty IgA antibodies, the same antibodies that build up in IgA nephropathy. So the same medicine that settles the blood cancer may also cool the inflammation in the kidney.
The honest limits
- This is a single patient (n=1), so it cannot show that ruxolitinib works for IgA nephropathy in general.
- Her IgA nephropathy came with a blood cancer, so her situation is unusual and may not apply to most people with stage 3 CKD.
- The kidney improvement overlapped with a later two-year steroid taper, so it is hard to separate what the JAK inhibitor did from what the steroids did.
- The abstract gives no exact protein or creatinine numbers and does not list any conflict-of-interest disclosures, so we cannot judge those here.
- My kidney disease is on its own, without a blood cancer like polycythemia vera. Is a JAK inhibitor like ruxolitinib even relevant to me?
- For my IgA nephropathy, what treatments have actual trial evidence behind them, not just single case reports?
- How do you weigh the risks and side effects of steroids or JAK inhibitors against the benefit for someone with my kidney numbers?