The purpose of the Expanded Access Program is to provide pre-approval access of olezarsen to eligible patients with Familial Chylomicronemia Syndrome (FCS).

The Expanded Access Program (EAP) is intended to provide pre-approval access to olezarsen for eligible patients with FCS who have limited or no available treatment options. This program is open in the United States and operates under the individual patient (also referred to as single patient) IND expanded access route in which the patient's treating physician serves as the sponsor. Expanded access requests must be from the patient's treating physicians and submitted according to the instructions at https://www.ionispharma.com/patients/expanded-access-policy/

Inclusion Criteria:

• Has a diagnosis of FCS as determined by the sponsoring physician. Ionis will review each application to determine eligibility based on documentation of validated genetic or clinical diagnosis.

  o Documented loss of function mutations (homozygous, compound / double heterozygous) in genes such as LPL, GPIHBP1, APOA5, APOC2 or LMF1) or clinically validated diagnosis of FCS.

• Resides in and is a resident of the United States.

• Willing to follow a diet comprising ≤20 g fat per day.

Exclusion Criteria:

• Has any new or worsening of existing conditions which, in the opinion of the physician, would make the patient unsuitable for treatment with olezarsen.
• Olezarsen naïve patients with baseline platelet count <100x109/L at qualification.
• Estimated GFR (eGFR) <30 mL/min/1.73 m2.
• Secondary factors are the cause of triglyceride elevations.
• Is currently hospitalized in an acute emergency setting.