Adding tirzepatide to ixekizumab improved psoriatic arthritis response in people with obesity

Design

Phase 3b randomised trial, 52 weeks

Population

271 adults with active psoriatic arthritis and obesity, or overweight with a weight-related condition

Primary outcome

ACR50 plus at least 10% weight loss at 36 weeks

Effect

31.7% vs 0.8% (composite); ACR50 33.5% vs 20.4% (P = 0.02)

TOGETHER-PsA, published in March, randomised 271 adults with active psoriatic arthritis and obesity, or overweight with a weight-related condition, to ixekizumab plus tirzepatide or ixekizumab alone for 52 weeks.

The primary endpoint, combining an ACR50 response with at least 10% weight loss at 36 weeks, was met by 31.7% with the combination and 0.8% with ixekizumab alone; that composite is heavily driven by the weight-loss component. The more useful number is ACR50 alone: 33.5% with the combination against 20.4% with ixekizumab alone. Physical function, fatigue, minimal disease activity and skin scores also favoured the combination, and no new safety signals were seen.

Obesity is common in psoriatic arthritis and blunts response to biologics. This trial suggests treating weight alongside the joints improves the joints. Cost of a second injectable is the barrier for most Indian patients, and the trial did not test lifestyle-based weight loss, which remains the first step.

• Record BMI and weight-related conditions in every patient with psoriatic arthritis.
• Address weight actively as part of psoriatic arthritis treatment, starting with diet and activity support.
• Consider a GLP-1-based therapy alongside biologic treatment for patients with obesity where it is otherwise indicated and affordable.
• Coordinate with diabetology or obesity services rather than prescribing in isolation.
• Expect better function and fatigue as well as joint scores when weight falls.

Why it matters

It turns weight from a background risk factor into a treatment target in psoriatic arthritis.

Don't overread it

The primary endpoint bundled weight loss with joint response; the gain in ACR50 alone was 13 percentage points.

The statistics, in plain English

ACR50 of 33.5% versus 20.4% means about 13 more patients in every 100 halved their arthritis activity. The composite primary endpoint was almost impossible to reach without weight loss, so it overstates the joint benefit.

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