Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a vaccine cannot be directly compared to rates in the clinical trials of another vaccine and may not reflect the rates observed in clinical practice.
The safety of CYFENDUS was evaluated in 4 clinical studies, in which a total of 3,276 participants 18 through 65 years of age received at least one dose of CYFENDUS and were included in a pooled safety population.
Study 1 (NCT01263691) evaluated the safety and immunogenicity of different vaccine formulations administered intramuscularly two weeks apart in participants between 18 and 50 years of age. Seventeen participants received at least one 0.5 mL dose of CYFENDUS.
Study 2 (NCT01770743) evaluated the safety and immunogenicity of different dosing regimens of CYFENDUS in participants between 18 and 50 years of age. Forty-four participants received two doses of CYFENDUS via the intramuscular route two weeks apart.
Study 3 (NCT04067011) investigated potential interactions of intramuscularly administered CYFENDUS with the antibacterials ciprofloxacin or doxycycline, when administered concomitantly in participants between 18 and 45 years of age. Sixty-four participants received only CYFENDUS in the control arm.
Study 4 (NCT03877926) evaluated the safety and immunogenicity of CYFENDUS in participants between 18 and 65 years of age. CYFENDUS was administered intramuscularly as two doses at Weeks 0 and 2, with saline placebo given at Week 4. BioThrax was administered subcutaneously as three doses at Weeks 0, 2, and 4. The number of participants receiving at least one dose of CYFENDUS was 3151, while 2898 participants received the complete two dose regimen. [See Clinical Studies (14.1)]
The mean age for the pooled safety population across Studies 1-4 was 39 years; 32.1% of participants (n=1050) were between 18-30 years of age, 44.2% (n=1447) were between 31 to 50 years of age, and 23.8% (n=779) were between 51-65 years of age. Females comprised 57.8% (n=1895) of the population, with 40.4% (n=1325) being women of childbearing potential. The race distribution was as follows: 77.9% White, 17.1% Black or African American, 1.8% Asian, 1.7% Multiracial, 0.4% American Indian or Alaskan Native, 0.3% Native Hawaiian or Other Pacific Islander, 0.5% Other, and 0.2% Unknown. Most participants (83.9%) were not Hispanic or Latino.
Study 4 Solicited Local and Systemic Adverse Reactions
In Study 4, an active-controlled study, the licensed anthrax vaccine, BioThrax (Anthrax Vaccine Adsorbed), was used as the comparator. Solicited local and systemic adverse reactions reported following administration of any dose of CYFENDUS or BioThrax are presented in Table 1. CYFENDUS was administered intramuscularly as two doses at Weeks 0 and 2, with saline placebo given at Week 4. BioThrax was administered subcutaneously as three doses at Weeks 0, 2, and 4. The number of participants receiving at least one dose of CYFENDUS was 3151, while 2898 participants received the complete two dose regimen of CYFENDUS. There was no notable difference in the frequency of solicited local or systemic adverse reactions after the first or second dose of CYFENDUS, with the exception of itching (10.3% after first CYFENDUS dose vs. 16.8% after second dose), erythema/redness (7.4% after first CYFENDUS dose vs. 14.8% after second dose), swelling (10.2% after first CYFENDUS dose vs. 15.9% after second dose) and fever (2.7% after first CYFENDUS dose vs. 5.0% after second dose).
Table 1 Percentage (%) of Participants with Solicited Local or Systemic Adverse Reactions within 7 Days Following Administration of Any Vaccine Dosea in Study 4b| a 3151 participants received at least one dose, and 2898 participants received two doses of CYFENDUS. |
| b Percentage of participants reporting solicited local or systemic adverse reactions in e-diaries and during in-clinic reactogenicity assessments for at least 7 days following any dose (CYFENDUS up to two doses intramuscularly, BioThrax up to three doses subcutaneously). |
| c No Grade 4 local adverse reactions were reported for CYFENDUS. For all local adverse reactions, Grade 3 included a criterion that the symptom prevents activities of daily living or requires treatment. Some local adverse reactions included additional or alternative Grade 3 criteria as noted in the respective footnotes. |
| d Pain: Grade 3 = Pain requires use of narcotic pain reliever or prevents daily activity; Grade 4 = Emergency Room visit or hospitalization. |
| e Induration/swelling: Any Grade = ≥2.5 cm and does not interfere with activity; Grade 3 = >10 cm or prevents daily activity; Grade 4 = Necrosis. |
| f Erythema/redness: Any Grade = ≥2.5 cm; Grade 3 = >10 cm; Grade 4 = Necrosis or exfoliative dermatitis. |
| g No Grade 4 systemic adverse reactions were reported for CYFENDUS. Systemic adverse event: Grade 1 = Mild; Grade 2 = Moderate; Grade 3 = Severe (symptom prevents activities of daily living or requires treatment); Grade 4 = Severe (potentially life threatening). |
| h Fever (oral temperature): Grade 1 = 38.0-38.4ᵒC; Grade 2 = 38.5-38.9ᵒC; Grade 3 = 39.0-40ᵒC; Grade 4 = >40ᵒC. |
| CYFENDUS | CYFENDUS | CYFENDUS | BioThrax | BioThrax | BioThrax |
| N | Any Grade | Grade 3+ | N | Any Grade | Grade 3+ |
Local Adverse Reactionsc | | | | | | |
Any Injection Site Reaction | 3106 | 93.0% | 3.8% | 527 | 94.9% | 4.6% |
Tenderness | 3106 | 88.1% | 1.7% | 527 | 89.9% | 0.8% |
Paind | 3106 | 86.3% | 2.1% | 527 | 87.9% | 0.9% |
Arm Motion Limitation | 3106 | 63.7% | 1.7% | 527 | 51.4% | 0.4% |
Warmth | 3106 | 51.2% | 0.7% | 527 | 68.7% | 0.2% |
Induratione | 3106 | 37.5% | 0.3% | 527 | 75.5% | 1.1% |
Itching | 3106 | 21.9% | 0.4% | 527 | 58.8% | 0.8% |
Swellinge | 3106 | 19.7% | 0.4% | 527 | 55.4% | 1.3% |
Erythema/ Rednessf | 3106 | 17.9% | 0.9% | 527 | 53.9% | 1.9% |
Bruising | 3106 | 17.2% | 0.3% | 527 | 34.9% | 0.0% |
Systemic Adverse Reactionsg | | | | | | |
Any Systemic Reaction | 3115 | 84.3% | 6.6% | 528 | 78.4% | 3.8% |
Muscle Ache | 3106 | 75.2% | 3.5% | 527 | 63.4% | 1.9% |
Tiredness | 3106 | 67.1% | 2.9% | 527 | 53.7% | 1.7% |
Headache | 3106 | 58.0% | 3.2% | 527 | 47.6% | 2.1% |
Feverh | 3113 | 6.8% | 0.7% | 527 | 1.7% | 0.4% |
Serious Adverse Events (SAEs) and Deaths
In the pooled safety population, serious adverse events including deaths were monitored for up to one year following the last vaccination. None of the reported deaths (n=6, 0.2%) or SAEs (n=62, 1.9%) were determined to be related to the administration of CYFENDUS.
Potentially Immune-mediated Adverse Events
In the pooled safety population, participants were monitored for the occurrence of new-onset potentially immune-mediated adverse events for 12 months after the first dose of vaccine. Events were adjudicated as to whether they were of autoimmune etiology by an external expert blinded to treatment assignment. As determined by the adjudicator, three events of autoimmune etiology in three participants were considered possibly related to the administration of CYFENDUS: (1) a case of ulcerative colitis that occurred 208 days after the administration of CYFENDUS, (2) a case of chronic idiopathic urticaria that occurred 76 days after the administration of CYFENDUS and (3) a case of diffuse alopecia that occurred 17 days after the administration of CYFENDUS.