All familial hypercholesterolemia (FH) or severe hypercholesterolemia participants who had tolerated the treatment regimen in Protocol 301012-CS5 (NCT00607373), 301012-CS7 (NCT00706849) or MIPO3500108 (NCT00794664) and satisfactorily completed the study through to Week 28 were eligible for participation in this open label treatment extension study for up to 4 years or until mipomersen was commercially available, whichever comes first. Consenting participants who had tolerated mipomersen and satisfactorily completed 301012-CS17 (NCT00477594) through Year 3 may also enroll for up to an additional 2 years of treatment in this study or until mipomersen was commercially available, whichever comes first. All participants, who entered the study, received 200 mg mipomersen (ISIS 301012) subcutaneously (s.c.) every week, including those who were randomized to placebo in their initial study. Participants who were originally enrolled in Protocol 301012-CS5 (NCT00607373) and weighed \<50 kg received 160 mg every week. Dose adjustments (70 mg injections administered three times per week, on separate days) were allowed for participants who were not tolerating or who had previous issues with tolerating the once a week injections due to injection site reactions (ISRs) or flu-like symptoms. Study visits and clinical lab assessments including hematology with differential, chemistry, serum lipid panel (total cholesterol, LDL-C, very low density lipoprotein cholesterol (VLDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein B (apoB), apoA-1, triglycerides (TG) and Lp(a), and urinalysis was to be performed every 4-10 weeks during the treatment period. Plasma trough mipomersen (ISIS 301012) levels was to be measured to estimate exposure. Participants who completed dosing or who discontinued prematurely from the study for any reason was followed for safety for 24 weeks (safety follow-up period) after their last dose of mipomersen (ISIS 301012) or longer in the case of a significant adverse events (AE) or abnormal biochemical or clinical finding. Participants were required to return to the study center for clinical evaluation and clinical laboratory tests every 8 weeks during the safety follow-up period.
