AnaptysBio's Arthritis Drug Matches Top Therapies In Phase 2 Trial, Analyst Sees Turning Point

AnaptysBio, Inc. ANAB on Tuesday released updated data from the Phase 2b trial of rosnilimab, a PD-1 depleter and agonist, for rheumatoid arthritis.

In the 424-patient 2b trial, rosnilimab achieved JAK-like efficacy on multiple clinically meaningful measures, including low disease activity (LDA) and remission on the Clinical Disease Activity Index (CDAI), as well as ACR70 response, over six months.

Furthermore, responses were then durable for at least two months off the drug.

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Rosnilimab was safe and well tolerated, particularly compared to standard-of-care biologics or JAKs.

All three doses (100mg Q4W, 400mg Q4W, 600mg Q2W) achieved statistically significant reductions in DAS-28 CRP and ACR20 at Week 12 versus placebo.

CDAI LDA (≤10) was achieved by 45% of 318 rosnilimab patients by Week 12, increasing to 69% (220 responders) across all doses by Week 14.

The company aims to complete its Phase 2 study for rosnilimab in ulcerative colitis/UC, with initial data expected in the fourth quarter of 2025.

As of the March 11, 2025 data cutoff date, 83% were still in LDA at Week 34 across all doses. Of the remaining 17% of patients who did not sustain CDAI LDA at Week 34, most remained near the cutoff of CDAI=10, with a median CDAI of 13.

Rosnilimab demonstrated clinically meaningful improvements that deepened through Week 28 across multiple validated patient-reported outcomes, including the pain visual analog scale (VAS) and the health assessment questionnaire, or HAQ-Disability Index (DI), a self-reporting tool to measure function and disability.

HC Wainwright analyst Emily Bodnar wrote on Wednesday, “Given the data showcase a positive holistic story for rosnilimab in RA, we are increasingly positive on upcoming UC data.”

Bodnar upgraded AnaptysBio from Neutral to Buy, raising the price target from $22 to $38.

HC Wainwright Highlights Competitor Datasets

Data using non-responder imputation (NRI) from Week 24 of the SELECT-CHOICE trial, which compared AbbVie Inc’s ABBV Rinvoq vs Bristol Myers Squibb & Co’s BMY Orencia in rheumatoid arthritis (RA), showed similar results for both drugs. These findings align with the results seen for the company’s rosnilimab at Week 28, even though about 29% of patients had previously been treated with JAK inhibitors.

In contrast, Eli Lilly And Co‘s LLY now-discontinued PD-1 agonist peresolimab showed a drop in CDAI LDA rates—from 55% at Week 14 to 37% at Week 24. This is notably lower than the 53–63% range reported for rosnilimab at Week 28.

Johnson & Johnson JNJ is also set to present early data for its PD-1 agonist at the upcoming EULAR conference, though its study is smaller than AnaptysBio’s.

Price Action: ANAB stock is down 12.1% at $20.66 at the last check on Wednesday.

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