Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The data described below reflect a total treatment exposure of 789 patient-years in 285 patients who received Palynziq in an induction/titration/maintenance regimen in clinical trials [see Clinical Studies (14)]. Of the 285 patients, 229 patients were exposed to Palynziq for 24 weeks, 209 patients were exposed for 1 year, 181 patients were exposed for 2 years, and 160 patients were exposed for 3 years or longer. The patient population was evenly distributed between male and female patients, the mean age was 29 years (range: 16 to 56 years), and 98% of patients were White.
The most common adverse reactions (at least 20% of patients in either treatment phase) were injection site reactions, arthralgia, hypersensitivity reactions, headache, generalized skin reactions lasting at least 14 days, nausea, abdominal pain, vomiting, cough, oropharyngeal pain, pruritus, diarrhea, nasal congestion, fatigue, dizziness, and anxiety.
Of the 285 patients exposed to Palynziq in an induction/titration/maintenance regimen in clinical trials, 44 (15%) patients discontinued treatment due to adverse reactions. The most common adverse reactions leading to treatment discontinuation were hypersensitivity reactions (6% of patients) including anaphylaxis (3% of patients), angioedema (1% of patients), arthralgia (4% of patients), generalized skin reactions lasting at least 14 days (2% of patients), and injection site reactions (1% of patients).
The most common adverse reactions leading to dosage reduction were arthralgia (15% of patients), hypersensitivity reactions (9% of patients), injection site reactions (4% of patients), alopecia (3% of patients), and generalized skin reactions lasting at least 14 days (2% of patients).
The most common adverse reactions leading to temporary drug interruption were hypersensitivity reactions (14% of patients), arthralgia (13% of patients), anaphylaxis (4% of patients), and injection site reactions (4% of patients).
Table 2 lists adverse reactions reported in at least 15% of patients treated with Palynziq in an induction/titration/maintenance dosage regimen in clinical trials, and illustrates the adverse reaction rates over time by treatment phase. Table 3 lists laboratory abnormalities reported in at least 10% of patients treated with Palynziq in an induction/titration/maintenance dosage regimen in clinical trials.
For these analyses, the induction/titration phase was defined as the time prior to reaching a stable dose (completing an 8‑week phase at the same dose level). Once a stable dosage was reached, patients were considered to be in the maintenance phase thereafter. Safety data for patients who reached the maintenance phase are included within either the induction/titration or maintenance phases depending on the onset date of the adverse reaction. Safety data for patients who did not reach the maintenance phase are included within the induction/titration phase. The maintenance phase includes data for patients who were previously on Palynziq and transitioned to placebo during the randomized withdrawal period of Study 302 [see Clinical Studies (14)].
Rates of adverse reactions (adjusted for duration of exposure) generally decreased over time and for some stayed relatively stable. In the maintenance phase, the rate of adverse reactions (adjusted for duration of exposure) in patients who reached the maintenance phase was comparable across dosages evaluated. The types and rate of adverse reactions reported during the maintenance phase in patients who received 20 mg once daily, 40 mg once daily, and 60 mg once daily were similar. During long-term treatment (greater than 36 months), the exposure-adjusted rates of adverse reactions decreased.
Rates of laboratory abnormalities (adjusted for duration of exposure) stayed relatively stable over time, except for complement C4 below lower limit of normal (LLN) and hs-CRP above 0.287 mg/dL over a 6 month period (both decreased over time) and hypophenylalaninemia (blood phenylalanine concentration below 30 micromol/L) on a single measurement (increased over time). There were no dose‑related trends in type or rate of laboratory abnormalities (adjusted for duration of exposure) reported during the maintenance phase in patients receiving 20 mg once daily, 40 mg once daily, or 60 mg once daily.
Table 2: Adverse Reactions Reported in at least 15% of PKU Patients Treated with Palynziq in an Induction/Titration/Maintenance Regimen in Clinical Trials – Incidence and Exposure-Adjusted RatesTreatment Phase Treatment Duration
| Induction/Titration Phase (N = 285) 141 person-years Mean: 188 days Median: 116 days Range: 1 to 2266 days
| Maintenance Phase (N = 225) 652 person-years Mean: 1087 days Median: 1158 days
Range: 5 to 2017 days
|
| Adverse Reaction | N (%) | Episodes (Rate) | N (%) | Episodes (Rate) |
| Injection site reactions Includes injection site: reaction, erythema, pruritus, pain, bruising, rash, swelling, urticaria, induration, hemorrhage, edema, mass, inflammation, nodule, discoloration, warmth, hematoma, irritation, vesicles, hypersensitivity, papule, discomfort, scar, paresthesia, hypertrophy, extravasation, dryness, scab | 252 (88%) | 2965 (21) | 166 (74%) | 2169 (3.3) |
| Arthralgia Includes arthralgia, pain in extremity, back pain, musculoskeletal pain, neck pain | 211 (74%) | 1049 (7.4) | 154 (68%) | 893 (1.4) |
| Hypersensitivity reactions | 153 (54%) | 634 (4.5) | 145 (64%) | 845 (1.3) |
| Headache Includes headache, migraine, sinus headache | 102 (36%) | 214 (1.5) | 126 (56%) | 1049 (1.6) |
| Generalized skin reaction lasting at least 14 days | 61 (21%) | 97 (0.7) | 93 (41%) | 186 (0.3) |
| Nausea | 52 (18%) | 68 (0.5) | 69 (31%) | 141 (0.2) |
| Abdominal pain | 39 (14%) | 54 (0.4) | 67 (30%) | 162 (0.3) |
| Vomiting | 36 (13%) | 53 (0.4) | 68 (30%) | 139 (0.2) |
| Cough | 27 (9%) | 33 (0.2) | 67 (30%) | 100 (0.2) |
| Oropharyngeal pain | 38 (13%) | 45 (0.3) | 65 (29%) | 108 (0.2) |
| Pruritus | 58 (20%) | 102 (0.7) | 61 (27%) | 424 (0.7) |
| Diarrhea | 26 (9%) | 32 (0.2) | 61 (27%) | 116 (0.2) |
| Nasal congestion | 12 (4%) | 16 (0.1) | 61 (27%) | 87 (0.1) |
| Fatigue | 37 (13%) | 81 (0.6) | 55 (24%) | 110 (0.2) |
| Dizziness | 47 (16%) | 65 (0.5) | 48 (21%) | 100 (0.2) |
| Anxiety | 14 (5%) | 23 (0.2) | 48 (21%) | 100 (0.2) |
| Alopecia | 13 (5%) | 14 (0.1) | 43 (19%) | 62 (0.1) |
Table 3: Laboratory Abnormalities Reported in at least 10% of PKU Patients Treated with Palynziq in an Induction/Titration/Maintenance Regimen in Clinical Trials – Incidence and Exposure-Adjusted RatesTreatment Phase
Treatment Duration | Induction/Titration Phase (N = 285) 141 person‑years Mean: 188 days Median: 116 days Range: 1 to 2266 days | Maintenance Phase (N = 225) 652 person‑years Mean: 1087 days Median: 1158 days Range: 5 to 2017 days |
| Laboratory Measurement | N (%) | Episodes (Rate) | N (%) | Episodes (Rate) |
| Complement factor C3 below LLN | 195 (68%) | 453 (3.2) | 188 (84%) | 2259 (3.5) |
| C-reactive protein (CRP) above ULN | 182 (64%) | 359 (2.5) | 160 (71%) | 1414 (2.2) |
| Hypophenylalaninemia on a single measurement | 53 (19%) | 216 (1.5) | 147 (65%) | 1553 (2.4) |
| Complement factor C4 below LLN | 177 (62%) | 318 (2.3) | 111 (49%) | 714 (1.1) |
| Hypophenylalaninemia on 2 or more consecutive measurements | 45 (16%) | 62 (0.4) | 111 (49%) | 204 (0.3) |
| Blood creatine phosphokinase (CPK) above ULN | 50 (18%) | 88 (0.6) | 108 (48%) | 377 (0.6) |
| Hs-CRP above 0.287 mg/dL over a 6 month period | 34 (12%) | 34 (0.4) | 36 (16%) | 46 (0.1) |
LLN – lower limit of normal
ULN – upper limit of normal
Hs – high sensitivity
Description of Selected Adverse Reactions
Arthralgia
In clinical trials, 245 out of 285 (86%) patients experienced episodes consistent with arthralgia (includes back pain, musculoskeletal pain, pain in extremity, and neck pain).
Arthralgia episodes were more frequent during the induction/titration phase (7.4 episodes/patient-year) and decreased over time (1.4 episodes/patient-year in the maintenance phase).
Forty-four out of 285 (15%) patients had one episode of arthralgia, 32 (11%) patients had 2 episodes of arthralgia, 18 (6%) had 3 episodes of arthralgia, and 146 (51%) had 4 or more episodes of arthralgia. Arthralgia occurred as early as after the first dose of Palynziq and occurred at any time during treatment. The mean duration of arthralgia was 16 days (median: 3 days, range: 1 to 936 days), and 19% of arthralgia episodes had a duration of at least 14 days. Severe arthralgia (severe pain limiting self-care activities of daily living) was reported by 11 (4%) patients. In addition to arthralgia, other joint-related signs and symptoms reported were: joint swelling (24 patients; 8%), joint stiffness (22 patients; 8%), and musculoskeletal stiffness (20 patients; 7%). Arthralgia episodes were managed with medications (e.g., nonsteroidal anti-inflammatory drugs, glucocorticoids, and acetaminophen), Palynziq dosage reduction (4% of episodes), Palynziq interruption (4% of episodes), or Palynziq withdrawal (0.6% of episodes). 97% of arthralgia episodes were reported as resolved at the time of last observation (up to 77 months of follow‑up).
Injection Site Reactions
Injection site reactions were reported as early as after the first dose of Palynziq and occurred at any time during treatment. Injection site reactions were more frequent during the induction/titration phase (21 episodes/patient-years) and decreased over time (3 episodes/patient‑years in the maintenance phase). The mean duration of injection site reaction was 10 days (median: 2 days, range: 1 to 1612 days), and 8% of injection site reactions had a duration of at least 14 days. 99% of injection site reactions were reported as resolved at the time of last observation (up to 77 months of follow‑up).
Three injection site reactions consistent with granulomatous skin lesions were reported (each reaction occurring in one patient): granulomatous dermatitis (occurred after 464 days of Palynziq treatment and lasted 16 days), xanthogranuloma (occurred after 378 days of Palynziq treatment and lasted 638 days) was treated with a topical antihistamine, corticosteroid, and Palynziq treatment was discontinued, and necrobiosis lipoidica diabeticorum (occurred after 281 days of Palynziq treatment and lasted 281 days). Necrobiosis lipoidica diabeticorum was treated with steroid injections and complicated by Pseudomonas infection. All three injection site reactions resolved.
One patient reported soft tissue infection (occurred after 196 days of Palynziq treatment and lasted 8 days) associated with mesenteric panniculitis treated with antibiotics, which resulted in treatment discontinuation.
Generalized Skin Reactions (not limited to the injection site) Lasting at Least 14 Days
In clinical trials, 134 out of 285 (47%) patients treated with Palynziq experienced generalized skin reactions (not limited to the injection site) lasting at least 14 days. Mean duration of these reactions was 63 days (median: 37 days; range: 14 to 638 days). Generalized skin reactions were more frequent during the induction/titration phase (0.7 episodes/patient‑years), and decreased over time (0.3 episodes/patient-years in the maintenance phase).
The mean time from first dose of Palynziq to onset of skin reactions was 373 days (median: 213 days; range: 2 to 1970 days). 5% of these reactions persisted at least 180 days, and 86% of these reactions were reported as resolved at the time of last observation (up to 77 months of follow‑up).
Angioedema
In clinical trials, 22 out of 285 (8%) patients experienced 45 episodes of angioedema (symptoms included: pharyngeal edema, swollen tongue, lip swelling, mouth swelling, eyelid edema and face edema) occurring independent of anaphylaxis. Angioedema (included under Hypersensitivity in Table 2) was more frequent during the induction/titration phase (0.14 episodes/patient-year) and decreased over time (0.04 episodes/patient-year in the maintenance phase). Three patients discontinued treatment. All episodes resolved. Angioedema can present as a symptom of anaphylaxis [see Warnings and Precautions (5.1)].
Serum Sickness
In clinical trials, serum sickness was reported in 7 out of 285 (2%) patients. Serum sickness episodes were more frequent during the induction/titration phase (0.04 episodes/patient-year) and decreased over time (less than 0.01 episodes/patient-year during the maintenance phase). All serum sickness reactions resolved without sequelae (duration of serum sickness ranged from 1 to 8 days). Out of the 7 patients who experienced serum sickness, 5 patients continued treatment without a recurrence, and managed serum sickness with drug interruption, dosage reduction and/or concomitant medication. Two patients discontinued treatment.