AnaptysBio may have ended last year on a low, but 2025 is looking up with the news that its PD-1 agonist rosnilimab has hit the goals of a phase 2 rheumatoid arthritis (RA) trial.
The phase 2b RENOIR study assessed three doses of subcutaneous rosnilimab—100 mg every four weeks, 400 mg every four weeks or 600 mg every two weeks—versus placebo in 424 patients with moderate-to-severe RA who were also receiving standard antirheumatic drugs such as methotrexate.
All three doses hit the trial’s primary endpoint of demonstrating a statistically significant change from baseline in disease activity after 12 weeks, the company said in a Feb. 12 release. Specifically, the 100 mg and 600 mg dose cohorts saw a mean reduction of 2.06 in the DAS28-CRP score, while the 400 mg cohort saw a reduction of 2.12.
In a 2025 lookahead last month, TD Owen analysts had described the trial's readout as “hotly debated” in the wake of Eli Lilly halting its own PD-1 program in RA last year.
The secondary endpoints of Anaptys' study assessed treatment response and disease activity at Week 12 and 14. On these measures at Week 12, rosnilimab achieved statistical significance “in at least one dose and numerical superiority at all doses … even though higher than typical placebo rates were observed,” the biotech said.
The San Diego-based company pointed to the 69% of rosnilimab-treated patients who met the target of reduced disease activity at Week 14 as a sign of the drug’s potential.
“We are excited about these trial results and the impact they could have on patients living with RA,” Anaptys CEO Daniel Faga said in the release. “Rosnilimab is safe and well tolerated with the highest ever reported CDAI low disease activity at ~3 months that, to date, is sustained and potentially deepening over six months.”
“These findings, further supported by objective translational data, surpass our target product profile in the ~$20 billion U.S. RA market,” Faga added.
The readout marks some welcome good news for Anaptys, which dropped an atopic dermatitis candidate in December after the compound failed to reduce eczema area and itch severity in a phase 2b trial.
The company will be hoping the good luck continues for its phase 2 readout of rosnilimab in ulcerative colitis, which is penciled in for the fourth quarter.
The biotech entered 2025 with about $415 million in the bank, which it expected to fund operations through the end of 2027, excluding potential milestone and royalty payments from its immuno-oncology partnership with GSK.
Earlier this month, Vanda Pharmaceuticals agreed to pay $10 million upfront for the license to Anaptys’ phase 3-stage pustular psoriasis drug imsidolimab.