Analysis of Mandatory Post‐Marketing Surveillance Studies Supports Revised Regulatory Requirements in Korea

PURPOSE: The objective of this analysis was to determine the contribution to the understanding of product benefit/risk made by non-randomized, observational post-marketing surveillance (PMS) studies previously required by the Ministry of Food and Drug Safety (MFDS) re-examination system and conducted by Pfizer in Korea over 2000-2024. METHODS: A retrospective analysis of all Pfizer Korea PMS studies during 2000-2024 was performed, covering a wide range of therapy areas. Available Pfizer clinical study reports and re-examination reports were reviewed for sample sizes, study periods, and key safety and effectiveness findings. RESULTS: Twenty-four studies that enrolled 21 179 Korean participants were identified. Original sample sizes assigned by MFDS were typically either 600 or 3000 participants, but enrollment challenges were common and approximately half of the PMS studies were permitted to reduce sample size. Mean study duration (FSFV-LSLV) was 3.8 years. Safety findings were consistent with existing global safety data, with no clinically significant new safety information being generated from the PMS studies. CONCLUSIONS: PMS conducted by Pfizer in Korea were often challenging to recruit and generated data that were consistent with prior global data, with no evidence of clinically meaningful differences in Korean patients. These findings support MFDS's recent transition to a risk management plan (RMP) framework, with PMS only as needed, reducing mandatory requirements for newly approved drug products. Furthermore, when a PMS study is necessary to address a specific scientific uncertainty, MFDS allows individual determination of the sample size, which will improve the feasibility of conducting the study.