Stephen Hahn
Stephen M. Hahn is an American radiation oncologist and pharmaceutical executive who served as the 24th Commissioner of the U.S. Food and Drug Administration (FDA) from December 17, 2019, to January 20, 2021.[1][2] Prior to his appointment, Hahn held leadership positions in oncology, including as chief medical executive at MD Anderson Cancer Center, where he oversaw clinical operations and advanced radiation therapy research.[3][4] During his FDA tenure, Hahn navigated the agency's response to the COVID-19 pandemic, authorizing emergency use of diagnostics, therapeutics like convalescent plasma, and vaccines developed at unprecedented speed through initiatives such as Operation Warp Speed, enabling millions of doses to be administered shortly after regulatory clearance.[1] These actions facilitated rapid scaling of mRNA vaccine platforms, which demonstrated high efficacy in preventing severe disease based on clinical trial data submitted to the agency.[1] However, his leadership faced scrutiny, including backlash over initial emergency authorizations for hydroxychloroquine and convalescent plasma—later adjusted amid evolving evidence—and a public apology for overstating plasma's benefits in a press statement that implied unverified survival gains.[5] Hahn also resisted political pressures to approve a COVID-19 vaccine before the 2020 election, prioritizing data integrity despite tensions with administration officials.[6] Following his departure from the FDA at the end of the Trump administration, Hahn transitioned to the private sector, joining Flagship Pioneering as chief medical officer for its preemptive medicine initiative in 2021, leveraging his regulatory expertise to advance biotech ventures including those in vaccine technology.[7][8] More recently, in 2025, he became chief medical officer at Nucleus Radiopharma, a startup developing radiopharmaceuticals for cancer treatment, drawing on his background in radiation oncology.[9]Early Life and Education
Childhood and Family Origins
Stephen Hahn grew up in the Philadelphia area in a large Catholic family.[10][11] Details regarding his parents' professions or specific family lineage remain undocumented in public records, though his surname Hahn traces to German origins as a variant of Johannes. His early environment in suburban Philadelphia preceded his departure for undergraduate studies at Rice University in Houston, Texas, graduating with a bachelor's degree in biology in 1980.[12]Academic and Medical Training
Hahn earned a Bachelor of Arts degree in biology from Rice University in Houston, Texas, in 1980.[13] He then attended Temple University School of Medicine in Philadelphia, Pennsylvania, receiving his Doctor of Medicine degree in 1984.[14] [13] Following medical school, Hahn completed an internal medicine residency at the Hospital of the University of Pennsylvania.[13] He subsequently pursued a fellowship in medical oncology at the same institution, gaining specialized training in cancer treatment modalities.[13] Hahn then undertook a residency in radiation oncology at Fox Chase Cancer Center in Philadelphia, focusing on the application of radiation therapies for oncologic conditions.[13] This sequence of postgraduate training established his expertise as a clinician-scientist in oncology, particularly radiation-based interventions.[15]Pre-FDA Professional Career
Early Clinical Roles in Radiation Oncology
Following completion of his radiation oncology residency at the National Cancer Institute (NCI) in 1994, Hahn served as chief of the NCI's Prostate Cancer Clinic within the Clinical Pharmacology Branch from 1993 to 1995, where he managed patient care for prostate cancer cases and contributed to clinical investigations as a senior investigator.[16][17] This role involved direct clinical oversight of specialized oncology treatments, including radiation therapies, during his transition from fellowship training.[18] Subsequently, in the mid-1990s, Hahn practiced as a medical and radiation oncologist in Santa Rosa, California, engaging in community-based clinical care prior to entering academic positions.[16][19] This period marked his initial independent clinical application of radiation oncology techniques, focusing on patient treatment in a non-academic setting, which honed his expertise in delivering targeted radiation for various malignancies.[20] These early roles underscored Hahn's commitment to hands-on patient care, bridging federal research institutions and private practice, before he shifted toward faculty and leadership duties in 1996.[21]Leadership Positions at MD Anderson Cancer Center
Hahn joined the University of Texas MD Anderson Cancer Center in 2015 as division head and chair of the Department of Radiation Oncology, along with serving as a professor in the department.[1] [3] In this role, he directed clinical, research, and educational efforts within radiation oncology, building on his prior experience as chair of radiation oncology at Fox Chase Cancer Center.[3] In March 2017, amid a leadership transition following the departure of president Ronald DePinho and ensuing operational challenges including financial deficits, Hahn was appointed to a newly created position as deputy president and chief operating officer (COO).[11] [22] This appointment aimed to stabilize institution-wide operations under new president Peter Pisters. As COO, Hahn oversaw day-to-day management of MD Anderson's business, clinical, and faculty activities, with a focus on enhancing efficiency and excellence across the 22,000-employee organization.[3] In 2018, Hahn transitioned to the role of chief medical executive (CME), a position that emphasized oversight of clinical care quality, patient safety, and medical strategy at the center, which treats more than 140,000 patients annually.[1] [15] [3] He continued practicing as a radiation oncologist during this tenure, maintaining direct involvement in patient care while leading efforts to integrate clinical operations with research and innovation. Hahn held the CME position until his nomination for FDA commissioner in November 2019.[23]Tenure as FDA Commissioner
Appointment and Initial Priorities
President Donald Trump nominated Stephen M. Hahn, M.D., to serve as Commissioner of Food and Drugs on November 1, 2019, following the resignation of Scott Gottlieb earlier that year.[17] The Senate Committee on Health, Education, Labor, and Pensions held Hahn's confirmation hearing on November 20, 2019.[24] On December 12, 2019, the Senate confirmed Hahn by a vote of 72-18.[25] Hahn was sworn in as the 24th Commissioner on December 17, 2019, by Secretary of Health and Human Services Alex Azar.[26] Prior to his FDA role, Hahn had served as chief medical executive at the University of Texas MD Anderson Cancer Center, bringing expertise in oncology and clinical research to the position.[1] Upon assuming office, Hahn outlined initial priorities focused on advancing FDA's mission through data utilization, consumer empowerment, and innovation. In early statements, he emphasized recruiting and retaining top talent to strengthen agency capabilities.[27] By February 2020, he articulated three core priorities: unleashing data to inform decisions, empowering American consumers with better information and tools, and increasing choice and competition via regulatory innovation.[28] These efforts included overseeing the FDA's Technology Modernization Action Plan to enhance technological infrastructure and processes.[29] Hahn also committed to promoting innovation in drug development and public health improvements, drawing on his background to expedite access to therapies, particularly in oncology.[30]Pre-COVID Regulatory Reforms and Initiatives
Upon assuming office as FDA Commissioner on December 17, 2019, Stephen Hahn prioritized modernizing the agency's data infrastructure to accelerate regulatory reviews by integrating real-world evidence (RWE), including electronic health records, patient registries, and post-market studies, alongside traditional randomized clinical trial data.[31] This initiative aimed to enhance decision-making efficiency for complex therapies without compromising safety or efficacy standards, reflecting Hahn's background in oncology where adaptive data assessment could address unmet needs in serious diseases.[11] Hahn directed staff to identify opportunities for RWE incorporation, viewing it as a means to leverage emerging data sources for pragmatic regulatory outcomes.[31] In parallel, Hahn advanced tobacco product enforcement, inheriting and intensifying efforts against youth-targeted flavored e-cigarettes amid the ongoing vaping crisis. The FDA, under his leadership, maintained a policy of prioritized enforcement against unauthorized flavored cartridge-based products, issuing warning letters and pursuing market removals to curb adolescent use, which had surged to 27.5% among high school students by 2019. This built on pre-existing guidance but emphasized swift action during his early tenure, with over 1,000 warning letters sent in late 2019 and early 2020 to manufacturers and retailers of non-compliant products. Hahn also outlined broader operational priorities in a February 26, 2020, address, focusing on "unleashing data" through technological upgrades, empowering state partners for inspections and surveillance, and laying groundwork for food safety advancements via better traceability and predictive analytics.[28] These efforts sought to streamline processes inherited from prior commissioners, such as patient-focused drug development initiatives, while applying Hahn's clinical expertise to expedite approvals for oncology and rare disease treatments.[11] By early 2020, the FDA under Hahn had approved several novel cancer therapies using accelerated pathways, continuing a trend of record novel drug approvals to enhance patient access.COVID-19 Response and Operation Warp Speed
As FDA Commissioner, Stephen Hahn oversaw the agency's accelerated regulatory review of COVID-19 countermeasures amid the pandemic's emergence in early 2020. The FDA issued its first Emergency Use Authorization (EUA) for the antiviral remdesivir on May 1, 2020, based on data from the Adaptive COVID-19 Treatment Trial showing reduced recovery time in hospitalized patients.[32] Hahn directed the establishment of the Coronavirus Treatment Acceleration Program to expedite therapeutic development while upholding safety standards, resulting in over 240 EUAs for diagnostics and treatments by September 2020.[32] In May 2020, the U.S. government launched Operation Warp Speed (OWS), a public-private partnership to compress vaccine development timelines through funding and logistics, with FDA providing independent technical input on trial design, endpoints, and safety monitoring without compromising approval criteria.[33] [34] Hahn emphasized that OWS's financial commitments enabled parallel manufacturing but did not alter FDA's requirement for vaccines to demonstrate at least 50% efficacy (with a lower confidence interval bound above 30%) and favorable safety profiles in large-scale trials.[33] [35] On June 30, 2020, the FDA released guidance recommending phase 3 trials enroll 30,000 or more participants, including diverse demographics, with at least two months of safety follow-up data post-second dose.[33] Hahn publicly committed to data-driven decisions insulated from political influence, stating in August 2020 that "FDA will not approve or authorize any COVID-19 vaccine until our career scientists determine that the available data meet our rigorous standards for safety, effectiveness, and manufacturing quality."[33] Despite reported White House pressure for pre-election approvals, Hahn resisted premature EUAs, insisting in October 2020 on two months of safety data and issuing guidance for high efficacy thresholds, which delayed authorizations beyond initial timelines.[6] [36] The FDA's Vaccines and Related Biological Products Advisory Committee convened on December 10, 2020, to review Pfizer-BioNTech's submission, affirming the vaccine's 95% efficacy against symptomatic COVID-19 in a phase 3 trial of approximately 44,000 participants, with a median two-month safety follow-up showing no serious concerns beyond expected reactogenicity.[37] [38] Hahn authorized the EUA for Pfizer-BioNTech on December 11, 2020, for individuals 16 years and older, enabling initial distribution under OWS logistics. A similar EUA followed for Moderna on December 18, 2020, after review of trial data indicating 94.1% efficacy in 30,000 participants. These actions facilitated over 20 million doses administered by Hahn's resignation on January 20, 2021, while post-authorization surveillance via systems like VAERS monitored adverse events.[32]Specific Emergency Use Authorizations and Approvals
Under Hahn's leadership, the FDA issued emergency use authorizations (EUAs) for several COVID-19 therapeutics and vaccines, prioritizing rapid deployment amid the public health emergency while requiring data on safety and potential benefits. These actions were enabled by the Federal Food, Drug, and Cosmetic Act's provisions for EUAs when no adequate alternatives existed and benefits outweighed known risks.[39] The agency also authorized over 500 EUAs for diagnostics and devices by late 2020, facilitating widespread testing.[40] On March 28, 2020, the FDA granted an EUA for hydroxychloroquine sulfate and chloroquine phosphate to treat hospitalized COVID-19 patients, based on limited in vitro data and anecdotal reports of antiviral activity, despite the absence of randomized controlled trials demonstrating efficacy.[41] This authorization, which covered donated stockpiles from the Strategic National Stockpile, faced immediate scrutiny for insufficient evidence and reports of cardiac risks like QT prolongation.[42] It was revoked on June 15, 2020, after clinical trials, including a large randomized study, showed no benefit in reducing mortality or hospitalization duration and confirmed safety concerns in COVID-19 contexts.[43] The FDA issued an EUA for remdesivir, an investigational antiviral, on May 1, 2020, for treating hospitalized adults and children with severe COVID-19, supported by preliminary data from the Adaptive COVID-19 Treatment Trial (ACTT-1) indicating a modest reduction in recovery time from 15 to 10 days.[44] This was expanded to include hospitalized patients with milder disease later in 2020. Full approval followed on October 22, 2020, as Veklury, though subsequent analyses questioned its impact on mortality.[45] On August 23, 2020, the FDA authorized convalescent plasma for hospitalized COVID-19 patients, drawing from observational data in over 35,000 recipients suggesting lower mortality with high-antibody-titer plasma administered early.[46] The EUA emphasized use under investigational protocols with informed consent, amid expanded access programs, but lacked support from large randomized trials at issuance; later studies, such as the RECOVERY trial, found no significant benefit.[47] The FDA's vaccine EUAs marked a pivotal acceleration under Operation Warp Speed. On December 11, 2020, it authorized the Pfizer-BioNTech mRNA vaccine for individuals 16 years and older, based on a phase 3 trial of approximately 44,000 participants demonstrating 95% efficacy against symptomatic COVID-19 and a favorable safety profile, with monitoring for rare anaphylaxis.[48] Seven days later, on December 18, 2020, EUA was granted for the Moderna mRNA vaccine for those 18 and older, supported by trial data from about 30,000 participants showing 94.1% efficacy and similar safety signals.[49] These authorizations enabled initial distribution of over 20 million doses by January 2021, prioritizing high-risk groups.[50]| Date | Product | Category | Key Basis for EUA |
|---|---|---|---|
| March 28, 2020 | Hydroxychloroquine/Chloroquine | Therapeutic | In vitro antiviral data; revoked June 15, 2020 due to lack of efficacy.[43] |
| May 1, 2020 | Remdesivir | Therapeutic | ACTT-1 trial: reduced recovery time in severe cases.[44] |
| August 23, 2020 | Convalescent Plasma | Therapeutic | Observational data: mortality benefit with high-titer plasma.[46] |
| December 11, 2020 | Pfizer-BioNTech Vaccine | Preventive | Phase 3 trial: 95% efficacy.[48] |
| December 18, 2020 | Moderna Vaccine | Preventive | Phase 3 trial: 94.1% efficacy.[49] |