PLEGRIDY SIDE EFFECTS

SIDE EFFECTS

The following serious adverse reactions are discussed in more detail in other sections of labeling:

• Hepatic Injury
• Depression and Suicide
• Anaphylaxis and Other Allergic Reactions
• Injection Site Reactions
• Congestive Heart Failure
• Decreased Peripheral Blood Counts
• Thrombotic Microangiopathy
• Autoimmune Disorders
• Seizures

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of PLEGRIDY cannot be directly compared to rates in clinical trials of other drugs and may not reflect the rates observed in practice.

PLEGRIDY Via Subcutaneous Administration

In clinical studies (Study 1 and Study 2), a total of 1468 patients with relapsing multiple sclerosis received PLEGRIDY by subcutaneous injection for up to 177 weeks (41 months), with an overall exposure equivalent to 1932 person-years. A total of 1093 patients received at least 1 year, and 415 patients at least 2 years of treatment with PLEGRIDY. A total of 512 and 500 patients, respectively, received PLEGRIDY 125 micrograms every 14 days or every 28 days during the placebo-controlled phase of Study 1 (year 1). The experience in year 2 of Study 1 and in the 2-year safety extension study (Study 2) was consistent with the experience in the 1-year placebo-controlled phase of Study 1.

In the placebo-controlled phase of Study 1, the most common adverse drug reactions for PLEGRIDY 125 micrograms subcutaneously every 14 days were injection site erythema, influenza-like illness, pyrexia, headache, myalgia, chills, injection site pain, asthenia, injection site pruritus, and arthralgia (all had incidence more than 10% and at least 2% more than placebo). The most commonly reported adverse event leading to discontinuation in patients treated with PLEGRIDY 125 micrograms subcutaneously every 14 days was influenza-like illness (in less than 1% of patients).

Table 1 summarizes adverse reactions reported over 48 weeks from patients treated in the placebo-controlled phase of Study 1 who received subcutaneous PLEGRIDY 125 micrograms (n=512), or placebo (n=500), every 14 days.

Table 1: Adverse Reactions in the 48-Week Placebo-Controlled Phase of Study 1 with an Incidence 2% Higher for PLEGRIDY Than for Placebo

Flu-Like Symptoms

Influenza-like illness was experienced by 47% of patients receiving PLEGRIDY 125 micrograms every 14 days and 13% of patients receiving placebo. Fewer than 1% of PLEGRIDY-treated patients in Study 1 discontinued treatment due to flu-like symptoms.

Comparison Between Subcutaneous And Intramuscular Administration

An open-label, crossover study analyzed findings from 130 healthy volunteers to assess the bioequivalence of single doses of 125 micrograms of PLEGRIDY administered as a subcutaneous and intramuscular injection (Study 3).

The most commonly reported adverse reactions (with >10% incidence in either arm) across both treatment periods were chills (36% in IM vs 27% in SC), pain (22% in IM vs 14% in SC), headache (36% in IM vs 41% in SC), injection site pain (11% in IM vs 15% in SC), and injection site erythema (2% in IM vs 25% in SC). Overall, injection site reactions were reported in 14% via IM route as compared to 32% via SC route.

Immunogenicity

As with all therapeutic proteins, there is a potential for immunogenicity.

The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies in the studies described below with the incidence of antibodies in other studies or to other interferon beta-1a products may be misleading.

In Study 1, fewer than 1% of patients treated with PLEGRIDY SC every 14 days for 1 year developed neutralizing antibodies. Approximately 7% of PLEGRIDY SC-treated patients developed antibodies to the polyethylene glycol moiety.

No formal studies have been conducted with regards to immunogenicity of the intramuscular route of administration of PLEGRIDY.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of PLEGRIDY. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Anaphylactic Reactions

In post marketing experience, serious hypersensitivity reactions, including cases of anaphylaxis, have been reported following PLEGRIDY administration.