A Randomized, Double-Blind, Placebo-Controlled, Phase 3 Study of
ISIS 304801 Administered Subcutaneously to Patients with Familial
Chylomicronemia Syndrome (FCS)

1. Must give written informed consent to participate in the study (signed and dated) and any authorizations required by law
2. Age >= 18 years at time of informed consent
3. History of chylomicronemia as evidenced by documentation of lactescent serum (a creamy top layer after ultracentrifugation of a fasting blood sample) or documentation of fasting TG measurement >= 880 mg/dL (10 mmol/L)
4. A diagnosis of Familial Chylomicronemia Syndrome (Type 1 Hyperlipoproteinemia) by documentation of at least one of the following:
a. Confirmed homozygote, compound heterozygote or double heterozygote for known loss-of-function mutations in Type 1-causing genes (such as LPL, apoCII, GPIHBP1, or LMF1)
b. Post heparin plasma LPL activity of <= 20% of normal
5. Fasting TG >= 750 mg/dL (8.4 mmol/L) at Screening. If the fasting TG < 750 mg/dL up to two additional tests may be performed in order to qualify.
6. History of pancreatitis (defined as a documented diagnosis of acute pancreatitis or hospitalization for severe abdominal pain consistent with acute pancreatitis and for which no alternate diagnosis was made). Patients without a documented history of pancreatitis are also eligible but their enrollment will be capped at 28% (i.e., <= 14 of the 50 planned patients).
7. Willing to follow a diet comprising <= 20g fat per day during the study
8. Satisfy one of the following:
a. Females: Non-pregnant and non-lactating; surgically sterile (e.g., tubal occlusion, hysterectomy, bilateral salpingectomy, bilateral oophorectomy), post-menopausal (defined as 12 months of spontaneous amenorrhea in females > 55 years of age or, in females <= 55 years, 12 months of spontaneous amenorrhea without an alternative medical cause and FSH levels in the postmenopausal range for the laboratory involved), abstinent, or if engaged in sexual relations of child-bearing potential, patient is using an acceptable contraceptive method (refer to Section 6.3.1) from time of signing the informed consent form until 13 weeks after the last dose of Study Drug administration
b. Males: Surgically sterile, abstinent or if engaged in sexual relations with a female of child-bearing potential, patient is utilizing an acceptable contraceptive method (refer to Section 6.3.1) from the time of signing the informed consent form until 13 weeks after the last dose of Study Drug administration.

1. Diabetes mellitus with any of the following:
a. Newly diagnosed within 12 weeks of screening
b. HbA1c >= 9.0% at screening
c. Recent change in anti-diabetic pharmacotherapy (change in dosage or addition of new medication within 12 weeks of screening [with the exception of ± 10 units of insulin])
d. Anticipated need to change dose or type of medication during the treatment period of the Study [with the exception of ± 10 units of insulin]
e. Current use of GLP-1 agonists
2. Severe hypertriglyceridemia other than due to familial chylomicronemia syndrome
3. Active pancreatitis within 4 weeks prior to screening
4. History within 6 months of screening of acute or unstable cardiac ischemia (myocardial infarction, acute coronary syndrome, new onset angina), stroke, transient ischemic attack or unstable congestive cardiac failure requiring a change in medication or major surgery within 3 months of screening
5. Any of the following laboratory values at Screening
a. Hepatic:
• Total bilirubin > upper limit of normal (ULN), unless prior diagnosis and documentation of Gilbert*s syndrome in which case total bilirubin must be <= 3 mg/dL
• ALT > 2.0 x ULN
• AST > 2.0 x ULN
b. Renal:
• Persistently positive (2 out of 3 consecutive tests >= 1+) for protein on urine dipstick. In the event of a positive test eligibility may be confirmed by a quantitative total urine protein measurement of < 500 mg/24 hrs
• Persistently positive (2 out of 3 consecutive tests >= trace positive) for blood on urine dipstick. In the event of a positive test eligibility may be confirmed with urine microscopy showing <= 5 red blood cells per high power field
• Estimated creatinine clearance calculated according to the formula of Cockcroft and Gault < 50 mL/min
c. Cardiac Troponin I > ULN at Screening
d. LDL-C > 130 mg/dL at Screening
e. Any other laboratory abnormalities which, in the opinion of the Investigator or the Sponsor, would make the patient unsuitable for inclusion
6. Uncontrolled hypertension (BP > 160/100 mm Hg)
7. History of bleeding diathesis or coagulopathy or clinically significant abnormality in coagulation parameters at Screening
8. History of heart failure with NYHA greater than Class II
9. Active infection requiring systemic antiviral or antimicrobial therapy that will not be completed prior to Study Day 1
10. Known history of or positive test for human immunodeficiency virus (HIV), hepatitis C or chronic hepatitis B
11. Malignancy within 5 years, except for basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix that has been successfully treated
12. Treatment with another investigational drug, biological agent, or device within one month of screening, or 5 half-lives of investigational agent, whichever is longer
13. Unwilling to comply with lifestyle requirements (Section 6.3)
14. Use of any of the following:
a. Statins, omega-3 fatty acids (prescription and OTC), or fibrates unless on a stable dose for at least 3 months prior to screening and dose and regimen expected to remain constant during the treatment period. Patients taking OTC omega-3 fatty acids should make every effort to remain on the same brand throughout the study
b. Nicotinic acid or derivatives of nicotinic acid within 4 weeks prior to screening
c. Systemic corticosteroids or anabolic steroids within 6 weeks prior to screening unless approved by the Sponsor Medical Monitor
d. Atypical antipsychotic medications (e.g., olanzapine and clozapine) unless on a stable dose for at least 3 months prior to screening and dose and regimen expected to remain stable throughout the study
e. Antihypertensive medication unless on a stable dose for at least 4 weeks prior to screening and dose and regimen expected to remain constant during the treatment period
f. Glybera gene therapy within 2 years prior to screening
g. Oral anticoagulants (e.g., warfarin, dabigatran, rivaroxaban, and apixaban) unless on a stable dose for at least 4 weeks prior to screening and regular clinical monitoring is performed
h. Tamoxifen, estrogens or progestins unless on a stable dose for at least 4 months prior to screening and dose and regimen expected to remain constant during the treatment period
i. Plasma apheresis within 4 weeks prior to screening or planned during the study
j. Prior exposure to ISIS 304801
k. Any other medication unless stable at least 4 weeks prior to screening (Occasional or intermittent use of over-the-counter medications will be allowed at Investigator*s discretion)
15. Blood donation of 50 to 499 mL within 30 days of screening or of > 499 mL within 60 days of screening
16. Known hypersensitivity to any of the excipients of the Study Drug (ISIS 304801 or placebo)
17. Have any other conditions, which, in the opinion of the Investigator or the Sponsor would make the patient unsuitable for inclusion, or could interfere with the patient participating in or completing the study