Grateful to have been part of meaningful work at the FDA

A follow-up on 13+ months at the agency and on being fired 2 weeks ago

On Friday night, I read about Trump’s executive order to realign the US’s core vaccine recommendations with those of best practices from peer, developed countries and I felt proud of the work Martin Kulldorff and I did, along with many others, to present these best practices.

You can read the report here.

I will let the report speak for itself, but one thing I will say is I am happy Martin agreed to -and were invited to- put our names on it; I believe strongly that people should be willing to stand by their work. And, as the date suggests, we worked tirelessly through the holidays on this project and I am forever grateful to Martin for his commitment to accuracy and clarity. (Many others worked through their holidays and I thank them as well for making this report a reality).

Here are few sentences I want to highlight from the EO: “The scientific assessment found that the United States currently recommends more childhood vaccines than any peer nation, including more than twice as many vaccine doses as some European nations, and identified a set of consensus vaccines that are consistently recommended in all peer countries. The scientific assessment also found that, instead of implementing vaccination mandates, most peer nations maintain high childhood vaccination rates through public trust and education.”

One month earlier, I had presented Denmark’s core vaccination schedule at ACIP and also discussed that critical topic of mandates.

I’m not sure why I am choosing this blurry video photo

Christine Stabell Benn and I had originally brought attention to the Danish vaccination schedule, which is similar to that of Sweden and Norway, on a Sensible Medicine Podcast and then on this Substack, my most recent Substack post before starting at the FDA.

My firing

The news of the EO came exactly 2 weeks after I learned I was fired as head of FDA CDER after refusing to sign a resignation letter. The story is in Maryanne Demasi’s Substack and in the New York Times, both of whom I gave quotes to the night after the FDA took my ID, computers, phone and walked me out. To this day, there is a lack of transparency about the details behind my firing.

To all of those ask who fired me and why, you are asking the right questions and so far I know who denies doing it or being aware it was going to happen. While I am aware of a number of things I’m not saying just yet, trust me if I say you are not alone in asking “Who is pulling the strings here?”.

Earlier that day, May 15th, I read out loud media rumors of my impending resignation during meetings with CDER staff and I joked that no one would believe I was resigning since I had just completed my annual cybersecurity training that day. Haha.

Here was my X post from that night (I did not limit the comments or geography so I am not sure why the comments were quickly disabled):

As I had said numerous times as head of CDER - “No one should be forced to sign off on something they aren’t comfortable with”. I constantly asked review teams to speak up if they disagreed with conclusions that were drawn.

I believe strongly people should take responsibility for their work. I highlighted this at a couple large, internal talks I gave in CDER; I worried about the risk of a lack of accountability in a large government bureaucracy. But what I saw in my CDER colleagues pleasantly surprised me: In general, they showed a commitment to the mission of the FDA and a willingness to debate and stand up for what they believed. I learned a lot from these debates and they often changed my mind. Something else that is essential to the scientific process is keeping it free of political interference. I mentioned this often as well. While politics can help determine priorities, they should not interfere with interpretation of data. I think this is something we all can agree on whatever our own politics are.

But I’m getting away from the point, which is I had no intentions of resigning so I wasn’t going to sign a letter saying I did. I stood by the work I was involved in at the FDA over my 13+ months there and honored to have had the opportunity to serve my country. I also want to thank Commissioner Makary, President Trump and Secretary Kennedy for giving me that opportunity. Being able to do work with a purpose you believe in is such a gift.

Below is a list of accomplishments I am particularly proud of that the our FDA team -either in the Office of the Commissioner, in CBER or in CDER in the time since I started March 27th, 2025, the week before Dr. Makary started as commissioner.

Reducing Animal Testing

The first major project Marty asked me to take on was writing the Roadmap to Reduce Animal Testing. As Marty has said multiple times in public, this topic really was a passion of mine and I spoke at a number of conferences about it as I became increasingly informed by internal FDA experts. I hope that this initiative has a lasting effect at the FDA and in the world. I know it has an enormous amount of internal and external support.

We had follow up publications about this initiative in NEJM AI and JAMA as well as draft guidance documents on monoclonal antibodies and NAMs. There will also be a documentary coming out soon, which Marty and I were part of- though I see it has not been announced publicly yet, so stay tuned.

Modeling drug toxicity

What I viewed from the beginning of the reduction in animal testing initiative as very promising alternative to animal testing, was the development of toxicity modeling leveraging both internal FDA data and external industry, NIH, etc data to predict human responses to drugs. (can be validated by blinding it to known responses). This was alluded to in the roadmap and the initiative was announced publicly on multiple occasions. Unfortunately, Jeremy Walsh, the Chief AI Officer, who was central to this project as well as to modernizing the agency, including leading the Real Time Clinical Trials initiative and streamlining the application submission and review process was asked to resign the same day I was fired. IMO, my firing was nowhere near as consequential to the agency as the loss of Jeremy due to his very unique skillset.

If you have not seen this discussion on the Real Time Clinical Trials on initiative with Jeremy Walsh, Marty Makary, Dr. Emma Meagher (U Penn) and Dr. Jennifer Litton (MD Anderson) on FDA Direct, I highly recommend it.

SSRIs in pregnancy

On July 21st, Marty and I co-hosted a panel on SSRIs in pregnancy bringing to the public a discussion on safety concerns and unknowns and also touching on the current hot topic of withdrawal. Safety concerns that arise in the post-marketing space could IMO be discussed and acknowledged more often by the FDA.

We received so much positive feedback after this panel; one thing I am certain of is that we raised public awareness in spite of the truly bizarre takes by the mainstream media of this even. I also met a number of people on the panel that day whom I continue to be friends with. The list of experts is in the link above as is the video from the day.

Vaccines and FDA Ex-Officio

I was appointed FDA ex officio from my start at the FDA through December January 2026 and was lucky to work closely with CBER Center Director Vinay Prasad during most of this time. As discussed in ACIP meetings, vaccine topics during my tenure ranged from revamping post-marketing surveillance of vaccines to new risk-benefit analyses to thimerosal to aluminum to understanding and presenting what we do and do not know about benefits and risks of childhood vaccinations.

One safety signal that has largely escaped public attention is that of febrile seizures in children 6 months through 4 years of age in days 0-1 following influenza vaccination identified two influenza seasons in a row following tri and quadrivalent influenza vaccines. More details here.

Also, the Ixchiq Chikungunya vaccine was withdrawn from the market for reasons outlined here.

VAERS

While this topic deserves its own post, I would point you to Maryanne Demasi’s Substack again, which I think has the best summary of the issue of the pediatric deaths reported to VAERS following the COVID-19 vaccines. Though I can’t speak to how conclusions were drawn on any internal memo about either 10 (as initially stated by Dr. Prasad) or 7 deaths (as disclosed to Senator Johnson) of the 96 pediatric deaths reports, the release of the memo raises some questions:

• Is it likely Vinay confused 10 with 7?

• Even if there were “only” 2 probable deaths in children due to the vaccine, why were these not disclosed to the public 3-5 years ago?

• Who were the authors of the below memo and how did the reported cases meet or not meet the bar for “possible” to them (did the have their own biases?)?

  I’m sure the readers of this Substack will have additional questions, about the released information. We should all be able to agree timely transparency about deaths of children is important and this should apply equally to drugs and vaccines.

  

Six Months as Head of CDER

December 15th, 2025 was my official start date as Acting Director of CDER. It truly was an honor to have this role and I want to specifically highly some of there work from that center over the last 6 months.

Commissioner’s National Priority Voucher Pilot Program & Faster Review Times

With the help of the CNPV initiative, we saw faster mean approval times in CDER in 2026 than the previous four years- following COVID (and this was of course in spite of fewer staff- I commend my former CDER colleagues for the hard work and commitment). This was a slide I presented at the Stanford Drug Discovery Symposium at the end of April.

And we had met 100% of our regulatory decision deadlines in CDER in 2026

until the advisory committee was announced for Teplizumab accelerated approval for use in Stage 3 of Type 1 diabetes in patients 8-17 years. I think this decision to hold an advisory committee as well as the CR decision on Bitopertin demonstrated that the CNPV did not become a “rubber stamp” of approval but that we were committed to making apolitical, appropriate and legal regulatory decisions guided by the data- while also making the review process much faster on average.

Rare Diseases

As of my keynote speech at NORD (National Organization for Rare Diseases) on April 14th, 2026,

we had approved eight rare disease drugs in CDER since I started as center director. Rare disease treatments have been a passion of mine since doing my Physiatry residency at UC Davis and working at Shriners Hospital of Northern California. I hope our track record and the meetings we held while I was head of CDER reflect this.

Here are press releases on Zycubo for Menkes Disease, Avlayah for Hunter Syndrome and leucovorin, based on a literature review, for CFD-FOLR1. As head of CDER, I was not involved in uniQure and Replimune decisions, which I mention only because of the amount of press these received.

At NORD and Rare Disease Day at HHS, I connected with a number of rare disease patient advocates, including for Huntington’s disease, whom I remain in contact with through today as well as U Penn researchers.

Plausible Mechanism Guidance for Individualized Therapies

The plausible mechanism framework was initially introduced to the world by Vinay and Marty in NEJM in November of 2025 and is one of the most exciting initiatives at the FDA right now.

The draft guidance is linked to here.

We held three panels on this:

At JP Morgan.

At Rare Disease Day at HHS.

At the FDA.

This, CNPV, drug repurposing, more OTC drugs, better information about drug safety during pregnancy, more transparency about post-marketing surveillance and reducing animal testing are initiatives I would love to see continue in the future; there are many others but these are among my favorites.

I have also not gotten into the details of the importance of making complete response (CR) or rejection letters public so FDA is able to get its side of the story to the public, the much needed and overdue update to the labeling on HRT for women,

the reminder to sponsors and researchers to disclose (and not “file drawer” negative or otherwise hide) their research results on clinicaltrials.gov -as required by law.

I still feel I have not come close to giving a full picture of what we accomplished and you can imagine, there was much more to come and in progress. It will be interesting to follow the FDA from the sidelines now. I did feel like the political pressure to make/avoid certain decisions was increasing, unfortunately - as the topic of Marty’s resignation also suggested.

Summary

I have a lot more I could write… about striking the balance between incentivizing innovation & exercising regulatory flexibility with ensuring that each traditional or accelerated approval is backed by evidence that meets the FDA’s statutory requirements for approval and about fighting back against political pressure with data and knowledge of how to interpret evidence and clinical trials. I’m proud I did not once give in to political pressure to make a decision I was not comfortable with. I am grateful Marty gave me his full support for this from day one. I also need to mention that the endless creative ideas and initiatives of Marty and Vinay made the job very fun and rewarding.

But, finally, as I said to my dad on my second to last day of work: The most important part of my job was listening. I needed to learn how to make CDER employees’ jobs better, easier and more fulfilling. I also had an incredible amount to learn. One of the reasons it was my favorite job to date is I was continually faced with new, exciting topics to learn about and experts who could teach me very quickly. I never stopped having my beliefs challenged- even on my last day. And we really did make a difference. What may be surprising to my readers is I was pleasantly surprised by the support and help I received from FDA career staff who, even if they perceived we might have some disagreements - political or otherwise- ultimately believed well, in treating their colleagues with respect, and in their mission to serve the American people and to do the work they feel is so critical to the health of Americans. These are the types of details you didn’t read about in the media’s coverage of the FDA.