Obinutuzumab beat tacrolimus for remission in membranous nephropathy

In primary membranous nephropathy — an autoimmune kidney disease that leaks large amounts of protein into the urine — the antibody obinutuzumab produced complete remission far more often than the drug tacrolimus in a phase 3 trial: 37% of patients versus 6% at two years [s1]. But a key measure of longer-term kidney protection was not met, so the trial's formal chain of statistical tests stopped there, and the durable benefit remains unproven [s1].

Both halves of that result matter, and the second is the one most likely to be lost in the headline.

The disease and the drugs

Primary membranous nephropathy is caused by the immune system attacking the kidney's filtering membrane, producing heavy protein loss, swelling and, in a substantial minority of patients, a slow slide toward kidney failure [s1]. Treatment aims to switch off the antibody-producing immune cells and drive the protein leak into remission. Standard options include calcineurin inhibitors such as tacrolimus, the comparator here, and B-cell-depleting antibodies.

Obinutuzumab is a type II anti-CD20 antibody that clears B cells; it is already used in some blood cancers and autoimmune diseases [s1]. This site has covered its test in active lupus in the ALLEGORY trial. The drug is made by Genentech and Roche, which funded and ran this trial — its authors include company employees — so its results are read here as a company-sponsored study, with the independent trial data leading and any promotional framing set aside [s1].

How the trial was run

Adults with primary membranous nephropathy were randomly assigned in equal numbers to receive intravenous obinutuzumab or oral tacrolimus [s1]. A total of 142 patients underwent randomisation [s1].

The primary endpoint was complete remission at week 104 — defined as a urinary protein-to-creatinine ratio of 0.3 or lower together with a stable estimated glomerular filtration rate, or eGFR, the standard measure of kidney function [s1]. Key secondary endpoints, tested in a fixed sequence, included complete or partial remission at week 104, complete remission at the earlier week 76, and a measure of kidney-function decline: a sustained reduction in eGFR of at least 30% [s1]. Fixed-sequence testing means that once one endpoint in the chain fails to reach significance, the endpoints after it can no longer be claimed as statistically proven.

What it found

At week 104, complete remission occurred in 26 of 71 patients in the obinutuzumab group and 4 of 70 in the tacrolimus group — 37% versus 6% with multiple imputation for missing data, an adjusted difference of 31 percentage points (95% confidence interval, 18 to 44; P<0.001) [s1]. The analyses of complete or partial remission at week 104 and of complete remission at week 76 also favoured obinutuzumab [s1].

Then the chain broke. The analysis of a sustained eGFR reduction of at least 30% — the endpoint that speaks most directly to whether kidneys are being protected over time — did not show a significant treatment effect, so the endpoints below it in the hierarchy were not formally tested for significance [s1].

On safety, adverse events of grade 3 or higher were reported in 16 patients (22%) in the obinutuzumab group and 13 (19%) in the tacrolimus group; serious adverse events occurred in 12 patients (17%) and 10 (14%), respectively [s1].

What it does and does not establish

The remission result is large and clear: on the protein-leak measure that defines this disease, obinutuzumab clearly outperformed tacrolimus at two years [s1]. An accompanying editorial called the finding "a step forward" [s2].

But remission of proteinuria is a surrogate — a stand-in for the outcome patients actually care about, which is keeping their kidneys working and off dialysis. The trial was designed to test both, and it delivered convincingly on the surrogate while failing to demonstrate a difference on the harder measure of eGFR decline [s1]. Two years is a short window in a disease that damages kidneys over decades, and the eGFR endpoint may simply need longer to separate; but on the evidence in hand, the case that obinutuzumab preserves kidney function better than tacrolimus is not yet made [s1]. The safety profiles were broadly similar [s1].

What to watch

The question that will decide obinutuzumab's place in membranous nephropathy is whether its advantage in clearing protein eventually translates into fewer patients losing kidney function — the endpoint this trial could not confirm. Longer follow-up, and how guideline groups weigh a strong surrogate against an unmet hard endpoint, are what to watch next.

This article describes trial results. It is not medical advice, and nothing here should be used to start, stop or change treatment.

Sources

• Obinutuzumab or Tacrolimus in Primary Membranous Nephropathy, New England Journal of Medicine, 5 June 2026
• A Step Forward — Obinutuzumab for Membranous Nephropathy, New England Journal of Medicine, 9 September 2026