The American College of Rheumatology’s annual meeting in Washington, D.C. turned out to be the perfect venue for major drug makers to provide updates on their respective psoriasis treatments.

Novartis (NVS), Celgene Corp. (CELG) and Pfizer Inc. (PFE) presented new data from their psoriatic arthritis studies, indicating promising prospects for their drugs and hinting at emerging competition. (For more, see 5 Best-Selling Prescription Meds Of All Time.)

Novartis said its Cosentyx drug (secukinumab) delivered sustained improvements for psoriatic arthritis in recent studies. Long-term data indicated that 77% of patients achieved the target mark of "20" on the American College of Rheumatology's (ACR) response scale at three years.

The ACR response scale measures the effectiveness of rheumatoid arthritis drugs in clinical studies. In trials for rheumatoid arthritis, standard criteria are used to compare the effectiveness of arthritis therapies, often reported as a percentage for ACR20, ACR50, ACR70.

For instance, if 55% of trial patients achieve ACR20, that means 55% of patients achieved a 20% improvement in tender or swollen joints, as well as a 20% improvement in three of the other five criteria.

Celgene’s Otezla was not far behind Cosentyx. Otezla's ACR20 response rate increased from 38% at week 16 to 67% at week 52. The result marks another milestone for Celgene, which recently secured NICE backing for Otezla. (For more, see Celgene's Otezla Gets NICE OK for Psoriasis.)

Pfizer’s Xeljanz also reported successful results. Both of its Phase III studies achieved the primary efficacy endpoint of a statistically significant improvement in psoriatic arthritis. The trials involved twice-daily doses of Xeljanz measuring 5 mg and 10 mg, compared to a placebo. (For more, see Pfizer May Sell Consumer Health Business.)

AbbVie Inc.’s (ABBV) Humira, the blockbuster drug for multiple indications, is an approved treatment for psoriatic arthritis. Humira is the bestselling drug in the world, with 2015 sales topping $14 billion. (See also: AbbVie Fends Off Humira Competitors.)

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