Wyatt McDonnell and the meeting that ran three hours

Wyatt McDonnell had half an hour with Jory Bell and Benjamin Kim. Three hours later, they were still talking at a whiteboard. The introduction to Playground Global had developed into something closer to a working session. An investor meeting had acquired the inconvenient habit of being interesting.

The conversation eventually led to more work: about a month spent with Kim and the team assembling a diligence document of roughly 100 pages. McDonnell liked the attention. Here were people willing to spend time on the details before deciding whether to back the company. For a scientist becoming a founder, that was a useful form of encouragement.

Today he is co-founder, CEO and board chairman of Infinimmune. Those titles arrive neatly on a line. Getting there required moving among disciplines, learning what he did well, and discovering that the person with the question sometimes has to become the person responsible for the company.

The education of a tool builder

McDonnell grew up in northern Michigan. The public library, museums and the natural world supplied early entertainment. A family friend once demonstrated a reaction that made a copper penny look silver. To a child, the change was startling. Chemistry had performed a trick and, better still, offered an explanation.

His route into formal research ran through Hillsdale College, where he worked in Frank Steiner’s laboratory and graduated in 2015. He then went to Vanderbilt, joining the laboratories of Simon Mallal and Ivelin Georgiev. The move brought him into a setting where experimental work and computational thinking could meet inside the same research question.

That combination became consequential. Graduate school gave him access to new single-cell instruments and to the problems created by their output. A machine could produce information; someone still had to make sense of it. McDonnell began learning to code. The interesting opportunity was sitting partly in the laboratory and partly on a computer.

There is a practical appeal to that kind of education. Each discipline supplies a different way to get stuck. Learning enough of a second one can change the first problem. For McDonnell, working across those boundaries became part of his professional identity, rather than an extracurricular addition to it.

He earned his master’s degree and doctorate at Vanderbilt, briefly joined its faculty, and moved to 10x Genomics in 2019. He was following technology he had already encountered as a researcher. Seeing people return to an instrument had caught his attention. Repeat use was a rather persuasive kind of recommendation.

A scientist learns what a product asks

At 10x, McDonnell helped develop BEAM, short for Barcode-Enabled Antigen Mapping, and worked on Immune Profiling v2. Product work added another kind of accountability to his research experience. An experiment could be interesting on its own terms. A product also had to become something another person could use.

His responsibilities extended into intellectual property and discussions about business opportunities. The company exposed him to the decisions behind building and commercializing technology. That matters in the story of a future CEO: the business education was happening alongside the technical work, attached to actual choices rather than a hypothetical company.

He also learned something less glamorous about himself. McDonnell has described his software-engineering limitations candidly, while identifying a strength in helping experimental and computational colleagues communicate. A founder biography can make every previous job look like a victory lap. His account leaves room for the useful discovery that some work suits you better than other work.

In his first month, he emailed senior leaders to introduce himself and discuss ideas. They made time even while preparing for the company’s IPO. He remembers that generosity. It is a small scene with a large implication: an unfamiliar employee could ask a question and find someone willing to consider it.

The experience also supplied future colleagues. David Jaffe, one of his eventual co-founders, had interviewed him at 10x. Other relationships formed across different kinds of work. When Infinimmune began, its founding group brought a history of making and analyzing things, as well as a shared interest in what to attempt next.

Five people, a shared starting point

The founding team comprised McDonnell, Jaffe, Katie Pfeiffer, Lance Hepler and Mike Gibbons. Their experience covered experimental science, computation, sequencing and data analysis. That mix gave the new company several ways to examine a problem. It also meant the CEO was beginning with collaborators who had substantial technical identities of their own.

In July 2022, a conversation over beer helped turn ideas into a venture. Incorporation, fundraising and proof-of-concept work followed. By the end of the year, Infinimmune had announced a $12 million seed round led by Playground Global, with Pear VC, Civilization Ventures and Axial participating.

The early company occupied a small California office. Looking back in September 2026, McDonnell described the journey from scientific observations to a business that could attract outside capital and partners. The progression took several kinds of persuasion: first among colleagues, then with investors, and eventually with a much larger corporate collaborator.

The founders had spent years around tools. Their new venture would apply that experience inside a business of their own. This was a change in responsibility as much as a change in employer. Choosing the question, assembling the team and paying for the work now belonged to the same organization.

McDonnell’s present colleagues still include several of those founders. Pfeiffer is chief technology officer, Gibbons chief scientific officer and Hepler chief information officer. Their titles show how the original group’s different specialties became part of the company’s operating structure. The shared starting point survived the arrival of an organizational chart.

The numbers have different jobs

On March 31, 2026, Infinimmune announced a collaboration with Merck. The agreement included an undisclosed upfront payment and eligibility for potential milestone payments totaling up to approximately $838 million. Merck received exclusive development and commercialization rights to candidates arising from the collaboration.

The conditional language deserves its space. A possible milestone payment belongs to the future and depends on progress. It should be read differently from money already raised through a financing. Large numbers can flatten a company story into a single impressive figure; the terms restore some useful detail.

In August, the company announced a separate $75 million Series A, co-led by Regeneron Ventures and Playground Global. New participants included RA Capital Management, Goldcrest Capital, Forge Life Science Partners, Godfrey Capital and Wild Tree Ventures. Several existing investors participated as well. Playground was continuing a relationship that went back to the seed round.

That continuity gives the original whiteboard meeting a second significance. Early attention had become an investment, and the investor returned for another financing years later. The company had acquired a longer record for people to examine. Its next conversations could begin with more than an account of what five founders hoped to build.

In October 2026, Infinimmune was named to Fierce Biotech’s Fierce 15. The recognition followed the financing and Merck announcement. Together, the three events mark a busy year in McDonnell’s public career. They are milestones in an ongoing company, with the subsequent work still ahead.

A job description without edges

For all the formal titles, McDonnell’s description of startup leadership is wonderfully unceremonious. “If you’re CEO of a startup, there’s nothing that isn’t your job at some point.” The sentence makes room for the ordinary, unphotographed demands that accompany decisions important enough to appear in a press release.

“If you’re CEO of a startup, there’s nothing that isn’t your job at some point.”

Wyatt McDonnell · Vanderbilt career symposium, 2023

His earlier career offers some preparation for that breadth. At different moments he has been a researcher, a computational colleague, a product developer and an inventor. The CEO role gathers those experiences into a job where attention itself becomes a resource: which conversation needs it, which decision can wait, which problem requires another person’s expertise.

He has also spoken about quantitative discipline and the need for experiments to inform decisions. It is a useful standard for a growing company. Collecting more information can feel productive while postponing a choice. Asking what the information will help decide gives the work a practical destination.

In a June 2026 conversation, he emphasized consistency, cost and scale in building datasets. Those considerations are familiar to anyone who has watched an elegant research project encounter an operating budget. More resolution can be interesting, but the company still needs a reason to pay for it. His emphasis connects the scientist’s interest in measurement with the executive’s responsibility to choose. A dataset becomes useful when the team can identify the decision it will inform, and build it reliably enough to use again.

Outside the job, he has listed piano, guitar, brewing beer at home and international travel among his interests. Those interests need no elaborate entrepreneurial interpretation. Music is allowed to be music. A person can have a hobby without making it audition for a place in the business plan.

His personal website is similarly economical. It greets the visitor and points to Infinimmune. For someone whose responsibilities have expanded so considerably, the introduction is brief. The longer account is in the work: the training, the colleagues, the products, the company and the conversations that kept going.

The whiteboard session is a fitting scene to return to. Before the later announcements, two investors and a scientist had found enough to discuss that a half-hour appointment became an afternoon. McDonnell had people willing to spend time with the question. There was plenty to do once they left the room.