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StocksMediumUpdated×2•Originally published 23 October 2026•Updated 23 October 2026•
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Roche Experimental Drug Cuts Urinary Protein 43.1% in Kidney Study of 459 Participants

Key Facts

1Sefaxersen cut urinary protein by 43.1% in Phase III data published on October 23, 2026.
2The IMAgINATION study included 459 participants, with random assignment in a 1:1 ratio and treatment set for 105 weeks.
3The blinded study will continue to assess kidney function at week 105.
4End-stage kidney disease may affect up to 50% of people with IgA nephropathy within 20 years of diagnosis, according to Genentech.

Genentech announced on October 23 that its experimental drug sefaxersen cut urinary protein by 43.1% in interim data from the Phase III IMAgINATION study, achieving a statistically and clinically significant result in people with IgA nephropathy. The result came at week 37, the trial’s primary endpoint assessment. The company said protein was measured by the protein-to-creatinine ratio in 24-hour urine. According to Genentech, a decline in this measure is strongly associated with long-term preservation of kidney function. But the study has not yet reached its extended kidney function measurement, and blinded follow-up will continue through week 105.

The study includes 459 participants, randomly assigned in a 1:1 ratio to sefaxersen or placebo, with treatment set for 105 weeks. Genentech’s statement described the trial as multicenter, randomized, double-blind and placebo-controlled. The primary endpoint is the change from baseline in the protein-to-creatinine ratio at week 37. This design enables a comparison of changes between the treatment and placebo groups within a single follow-up period, while the published result remains an interim measure. ClinicalTrials.gov confirms enrollment of 459 participants and classifies the trial as Phase III; the latest update posted to the registry was on August 14, 2026.

Genentech describes sefaxersen as an experimental, liver-targeted antisense oligonucleotide therapy that inhibits production of complement factor B. The drug is administered as a subcutaneous injection once monthly, with a design that allows patients to self-administer it. The approach focuses on producing a factor linked to the complement pathway, while the urinary protein measurement tracks the treatment’s effect on a marker associated with kidney damage. The broader clinical outcome remains under follow-up: the study continues to assess kidney function using estimated glomerular filtration rate at week 105, after about two years. The company said this assessment will take place while the study remains blinded.

Genentech said the safety and tolerability profile was consistent with previously reported data, with no new safety signals observed. This is the company’s description of the data available so far, as participants continue in trial follow-up. The available facts did not include additional numerical details on recorded events, while the week 37 measurement concerns urinary protein. The estimated glomerular filtration rate measurement at week 105 will test another aspect of response: changes in kidney function during follow-up. This reading remains tied to the ongoing study’s results.

IgA nephropathy is a chronic, progressive immune disease, and Genentech says it can lead to end-stage kidney disease in up to 50% of patients within 20 years of diagnosis. The company also says the disease affects at least 25 adults per million annually and is usually diagnosed before age 40. The 2025 KDIGO guidelines recommend targeting urinary protein excretion below 0.5 grams per day, and preferably below 0.3 grams per day. These targets put protein reduction in the context of disease monitoring, while IMAgINATION is also tracking kidney function over the course of the trial. The week 37 measurement remains part of this longer assessment, not its conclusion.

The presentation data were published on October 23, after the initial interim results were announced in September, and the 43.1% figure provided a urinary protein reduction number that was not available in the first statement. Meanwhile, kidney function follow-up is continuing through the week 105 measurement, according to the study design. Roche shares, listed under the ticker RHHBY, closed at $59.62 on October 22, the day before the presentation data were announced. The price therefore reflects a close before the data were published and does not measure the market’s response to them. The available facts did not include a subsequent price or an appropriate comparison to determine the announcement’s effect on the stock.