UPDATE 1-Amicus's fat accumulation drug effective in second late-stage study

(Adds detail; updates shares)

Aug 20 (Reuters) - Amicus Therapeutics Inc said its experimental drug was as effective as enzyme replacement therapies (ERTs) after 18 months in patients with Fabry disease, an inherited disorder that leads to the abnormal build-up of fat.

The company's stock rose 38 percent in premarket trading on Wednesday after the results of the second late-stage trial were released. They had jumped as much as 60 percent earlier.

Amicus said in April that the drug, migalastat HCl, significantly reduced the abnormal accumulation of fat, compared with a placebo, in patients with a form of Fabry disease.

Fabry disease is a potentially fatal disorder characterized by the buildup of a particular type of fat, most notably in the kidneys, caused by the deficiency of an enzyme called alpha-Gal A.

This progressive lipid accumulation results in cell damage, leading to pain, hearing loss, kidney failure, heart attack and stroke.

As a monotherapy, migalastat works by binding to the alpha-Gal A enzyme and helping it break down the lipids. The drug has an edge over standard treatment as it is administered orally, while ERTs require bi-weekly infusions.

The second late-stage trial was testing the drug against standard-of-care ERTs including Sanofi SA's Fabrazyme and Shire Plc's Replagal, in 60 patients, Amicus said on Wednesday.

Migalastat had a comparable effect to ERT on patients' kidney function - the main goal of the study, the company said.

GlaxoSmithKline returned the rights to migalastat to Amicus last November. Amicus is also testing migalastat in combination with the current standard-of-care for the disease.

Up to Tuesday's close of $4.57, the Cranbury, New Jersey-based company's stock had risen about 148 percent since the results of the earlier study were released on April 29.

(Reporting by Natalie Grover in Bangalore; Editing by Savio D'Souza)