It is because the government-funded trial was a placebo-controlled, double-blind, randomized controlled trial.

FORBES

The randomized, double-blind, placebo-controlled, multi-center trial enrolled 51 patients age 12 to 53 years, including 7 patients age 12 to 16 years, who were maintaining a regimen of maximally-tolerated lipid lowering medications.

FORBES: FDA Approves Mipomersen For Homozygous Familial Hypercholesterolemia