An experimental biotech drug developed by Johnson & Johnson proved more effective at clearing moderate to severe cases of the skin condition plaque psoriasis than a placebo or Abbvie Inc's big-selling Humira, according to data from a late stage study presented on Saturday.

The J&J drug, guselkumab, met the trial's primary goal, demonstrating statistically significant superior efficacy after 16 weeks of treatment and maintaining its advantage through week 48, the company said.

More than 73 percent of patients who received guselkumab experienced near complete skin clearance compared with 2.9 percent those who received a placebo. In the Humira group, nearly 50 percent of patients saw near complete skin clearance.

"These responses were durable and maintained through week 48," Dr. Andrew Blauvelt, lead researcher of the Phase III trial from the Oregon Medical Research Centre, said in a statement.

"Guselkumab also showed superior efficacy compared with adalimumab, with a separation in responses that was evident at week 16 and continued through the duration of the trial,” added Blauvelt, using the chemical name for Humira.

Humira, which also treats rheumatoid arthritis and other autoimmune conditions, is the world's top-selling prescription medicine.

The J&J drug also scored higher than placebo or Humira in an assessment of the treatment's effect on quality of life, researchers reported. The data was presented at the European Academy of Dermatology and Venereology (EADV) Congress in Vienna, Austria.

"The high and durable rates of response in skin clearance were associated with significant improvements in quality of life among patients treated with guselkumab," Professor Chris Griffiths, a member of the study's steering committee, said in a statement.

Serious adverse side effects, including some serious infections, were reported in 2.4 percent of guselkumab patients, 1.8 percent of those who got Humira and 1.7 percent in the placebo group.

Psoriasis is a chronic, autoimmune inflammatory disorder that results in sometimes painful, unsightly scaly and inflamed skin patches. An estimated 125 million people worldwide have psoriasis, including 7.5 million Americans, according to the National Psoriasis Foundation.