Novartis' $3.2B Chinook bet takes flight as phase 3 hits endpoint, providing launchpad for 2024 FDA filing

Novartis’ $3.2 billion bet on Chinook Therapeutics is taking off. Top-line phase 3 data show the acquired candidate improved a sign of kidney disease, positioning the Swiss drugmaker to apply for accelerated approval from the FDA next year.

Chinook took the asset, the oral endothelin A receptor antagonist atrasentan, to the cusp of phase 3 data before choosing to cash in its chips when Novartis came knocking earlier this year. The anticipated release of data from a pivotal trial of atrasentan in the fourth quarter provided an early test of whether Novartis was right to add atrasentan to its pipeline of IgA nephropathy (IgAN) candidates.

Early signs are good. Monday, Novartis revealed that the phase 3 clinical trial met its primary endpoint at an interim analysis. The study randomized around 340 patients with IgAN, a rare, progressive chronic kidney disease, to receive atrasentan or placebo.

At the 36-week interim analysis, Novartis saw that proteinuria, the medical term for protein in urine, had improved significantly more in the atrasentan arm than in the placebo cohort. Proteinuria is a sign of kidney disease. The improvement in proteinuria, which Novartis said was clinically meaningful and highly statistically significant, caused the study to meet its primary endpoint. 

On the safety front, Novartis said the profile seen in the clinical trial was consistent with the data from a midphase study. Chinook reported no treatment-related serious adverse events when it shared results from the midphase study one year ago.

Encouraged by the results, Novartis plans to file for accelerated approval in the U.S. next year. The Swiss drugmaker will continue to assess the kidney function of participants over 136 weeks to generate data to support full approval. Novartis expects to have top-line results from the confirmatory endpoint analysis in the first quarter of 2026.

The phase 3 data cap off a good month for Novartis’ IgAN team. At the start of October, Novartis reported positive phase 3 data from a trial of iptacopan, an oral factor B inhibitor that the company already had in its pipeline when it swooped on Chinook. A filing for accelerated FDA approval of iptacopan is planned for next year. Novartis has a second Chinook IgAN asset, zigakibart, in phase 3. 

Fierce Biotech contacted Novartis for clarification of the timing of the primary endpoint analysis in the atrasentan study. lists Week 24 as the time of the proteinuria analysis, but Novartis said the analysis took place at Week 36 in its press release. A spokesperson for Novartis said the "FDA recommended that we adjust the endpoint to 36 weeks in order to harmonize with other IgAN programs."