The accelerated approval (AA) pathway was established by the United States Food and Drug Administration (FDA) to provide earlier access to therapies for patients with serious medical conditions and unmet medical needs. Since its inception, the AA pathway has been used for novel treatments across different therapeutic areas, but most prominently in oncology, including the immune checkpoint inhibitor class. This review article describes the history of regulatory approvals for pembrolizumab, an immunotherapy agent targeting programmed death receptor-1 (PD-1), and use of the AA pathway and the corresponding regulatory decisions made by the FDA. From its first AA in September 2014 to February 2024, pembrolizumab has used the accelerated pathway for roughly 40% of the approved indications listed in the US Prescribing Information and was the first oncology therapy to receive an AA for an alternate dosing regimen and a tissue-agnostic indication. As of February 2024, 14 of the 18 indication-specific AAs and 1 post-marketing requirement (PMR) for the alternate dosing regimen AA were converted to traditional approvals. Accelerated approvals for two indications were withdrawn, and the remaining ongoing PMRs are not due until later in 2024 or 2025. The median conversion time from AA to traditional approval was 2.6 years, which is roughly 6 months earlier than the median time reported for oncology AAs. While FDA was the first agency to establish an expedited approval pathway, regulators from other countries have established similar pathways. For pembrolizumab, approximately half of the datasets that supported US AAs also supported expedited approval, or sometimes full approval, in Canada, EU, Australia or Japan. Ultimately, the AA pathway balances the provision of earlier access to therapies with overcoming uncertainty about potential effectiveness, and therefore it is important to confirm treatment benefit and withdraw indications that do not confirm benefit in a timely manner. The regulatory strategy and use of this expedited program for pembrolizumab highlights the importance of the AA pathway in providing oncology patients with earlier access to life-saving medications.
