(A-227) Adverse Drug Events Associated with Pembrolizumab In Pediatric Oncology: Analysis of Global and Local Individual Case Safety Reports

Background: Pembrolizumab is a programmed cell death protein 1 (PD-1) inhibitor approved by Saudi food and Drug Authority (SFDA) for pediatric patients aged 3 and older with relapsed or refractory classical Hodgkin lymphoma and those 12 and older with melanoma. Understanding its safety profile in pediatric populations is essential for optimizing treatment and ensuring patient safety.

Objectives: To describe reported adverse drug events (ADEs) associated with pembrolizumab in pediatric patients and evaluate the causality of these events.

Methods: A descriptive analysis was conducted using data retrieved from the World Health Organization ‘VigiBase (1967 to January 2025) and the SFDA’s National Pharmacovigilance Center. Inclusion criteria encompassed all individual case safety reports (ICSRs) for pediatric patients receiving pembrolizumab. We excluded case reports for individuals above 18 years. We assessed the causality of cases using the World Health Organization- causality assessment system.

Results: Demographics: 130 ICSRs associated with pembrolizumab in pediatric patients were identified. Indications were reported in 50 cases (38%): lymphoma (17 cases), stage IV melanoma (16), sarcoma (10), and hepatocellular carcinoma (7). Most patients were aged 12-17 years (54.6%), with 20% aged 2-11 years; 50.8% were female. The United States accounted for 36.2% of reports, with 41.5% submitted by physicians.
Common ADEs: Lack of efficacy/effectiveness (13%), death and product quality issues (7% each), and pain (5%). Arthralgia and diarrhea were reported in 3.1% of cases each. Serious cases comprised 61.5% of reports.
Causality

Assessment: Conducted for cases with a completeness score of ≥0.7 (n=26): possible due to reasonable temporality (n=16), unlikely due to unreasonable temporality (n=3), and un-assessable due to limited information (n=7).
Local Data: One case reported: a 12-year-old female with aggravated hyperthyroidism; due to missing temporal relationship information, this case was un-assessable.

Conclusions: This study highlights new safety concerns associated with pembrolizumab in pediatric patients, underscoring the need for ongoing monitoring and enhanced pharmacovigilance to safeguard this vulnerable population.