Li-Fen Lee Is Building a Biotech Around What the Immune System Misses

The pivotal moment in Li-Fen Lee’s career did not arrive as a flash of inspiration. It arrived as a queue of unanswered questions. After years spent studying how immune signals switch on, switch off, and misbehave, Lee founded Apeximmune Therapeutics around a stubborn premise: the familiar checkpoints could not explain every failure of the immune response. Somewhere inside the data were other brakes. The job was to find them, validate them, and make antibodies that could release them.

That premise contains the shape of her entire working life. Lee trained as a cancer immunologist at the University of North Carolina at Chapel Hill, where her 1998 doctoral thesis examined how paclitaxel triggers IL-8 expression in ovarian cancer cells. She received a Lineberger Graduate Fellow Award, then continued into postdoctoral training at Stanford University. Before entering industry, she held a faculty position at Stanford University School of Medicine.

The early papers show a researcher drawn to mechanisms rather than slogans. One line of work explored the signaling behind androgen independence in prostate cancer cells. Another examined how IL-7 influences immune-cell differentiation and might help distinguish responses to interferon-beta. These are different biological settings, but they share a practical instinct: identify the signal, locate its consequence, and ask whether that relationship can guide an intervention.

The scientist becomes a pipeline builder

At Pfizer, Lee moved from academic mechanism to industrial consequence. She led a drug-discovery group working on therapeutic antibodies against IL-7R and costimulatory molecules including 4-1BB. The intended uses stretched across autoimmunity and cancer. Her company biography credits that period with several investigational-new-drug filings, patents, and publications, as well as a Pfizer Achievement Award.

The patents form their own record of persistence. Lee is named on a family of inventions involving antagonist antibodies to the IL-7 receptor. Applications began appearing in 2011; grants followed in 2012, 2014, 2016, and 2018. Patent lists flatten the work into dates and titles, but the sequence suggests what drug development actually asks of a scientist: revisit one biological idea through years of experiments, claims, revisions, and handoffs.

Leadership roles at NGM and later Pharmacyclics, an AbbVie company, widened the aperture. Lee led immuno-oncology work, established core infrastructure, and helped build pipelines. The shift matters. A research result can belong to one project. Infrastructure has to make many projects more likely to succeed. By the time she started Apeximmune, Lee had worked on both sides of that divide.

“This funding marks a significant milestone in our journey to develop groundbreaking therapies that have the potential to improve patient outcomes.”Li-Fen Lee, on Apeximmune’s 2025 Series A

A company built to look past the obvious

Apeximmune’s central asset is not merely a drug candidate. It is a method for generating candidates. The company analyzes thousands of RNA-seq transcriptomes across more than 20 tumor types. It uses a proprietary T-cell gene-expression signature to separate tumors with strong T-cell signals from those with sparse ones. Differential analysis can then surface factors associated with suppressing active T cells or preventing their recruitment into the tumor environment.

The company says this process has produced more than 30 targets of interest. That abundance creates a less glamorous problem: choosing. A target has to be biologically relevant, accessible to a medicine, distinct enough to matter, and supported by evidence that survives increasingly expensive experiments. Platform companies are often described by how much they can discover. They are judged by how well they can narrow.

The first major selection is AIM-103, a protein Apeximmune describes as a negative immune-checkpoint target. It is expressed by dendritic cells and macrophages and is elevated in several cancers. The company’s research points to two categories of suppressive behavior: enzyme-dependent effects on the lipid environment and separate effects involving T-cell proliferation, macrophage activity, and dendritic-cell activation.

AI-306 is the antibody designed to block those functions. Apeximmune positions it as a possible complement to PD-1 therapies because it has observed higher AIM-103 expression following anti-PD-1 treatment, particularly in refractory patients. That remains a preclinical thesis, and the next stage is built to test it more rigorously.

Recruiting the immune system’s engulfing cells

Apeximmune’s other disclosed programs follow a different route. AI-328, AI-201, and AI-614 come from its macrophage-engaging bispecific antibody platform. Each construct is designed with two jobs: inhibit a macrophage-related target the company calls AIM-104, while binding a tumor-associated antigen that directs the immune cell toward a specific target.

The underlying concept is easy to picture. One side releases a brake on phagocytosis, the process by which a macrophage engulfs material. The other supplies an address. The company argues that this pairing may be relevant where tumors contain abundant myeloid cells but few lymphocytes. The disclosed programs use different tumor-associated-antigen pairings, allowing one platform idea to become several drug candidates.

This dual approach reveals something about Lee’s operating style without requiring a personality myth. The portfolio does not depend on a single immune cell or one familiar class of checkpoint. It follows the biology into T-cell suppression, dendritic-cell signaling, lipid metabolism, and macrophage activity. The common thread is a search for mechanisms that help a tumor make immune cells less effective.

From a grant-sized question to a venture-sized one

In June 2023, the National Cancer Institute awarded Apeximmune a Small Business Innovation Research grant totaling $399,618, publicly described as $400,000. The project supported preclinical development of AI-306. A month earlier, Lee and Apeximmune had been named among six semifinalists in the AIM-HI Women’s Venture Competition, selected from 71 applicants across 15 countries.

Those milestones validated different things. The grant backed a defined scientific program. The competition recognized a woman-led oncology venture and its case for a company. Neither removed the cost or uncertainty of developing an antibody. They helped Lee earn the right to pursue the next, larger question.

That question arrived in March 2025. Apeximmune announced a $21.3 million Series A, slightly above its original $20 million target. PharmaEssentia led the round. DCI Partners, Taya Venture Capital, KDI Marketing, Huahai US, Hercules BioVenture, and TTM 2025 also participated. The company said the proceeds would support AI-306 through IND-enabling work and toward clinical trials, expand research and development, and strengthen its scientific and executive teams.

For Lee, the financing changed the unit of work. A founder can describe a platform through its possibilities; a development-stage CEO must organize around gates. Toxicology, manufacturing, regulatory documentation, and trial design do not compress neatly into a discovery story. Every step produces a result that can narrow the company’s future as quickly as it expands it.

That is why the fundraising quote feels more precise than its ceremonial setting. Lee called the round “a significant milestone in our journey.” A milestone is not an arrival. It is a marker beside a longer road.

A repeatable way to ask better questions

Lee’s career can be read as a chain of increasingly consequential questions. At UNC, how does a cancer drug alter gene expression? At Stanford, what do immune mechanisms reveal when examined closely? At Pfizer, can those mechanisms become antibodies and filings? At NGM and AbbVie, can a team turn them into a pipeline? At Apeximmune, can the entire sequence become a company?

The useful lesson is not to romanticize the leap from scientist to founder. Lee’s path looks more cumulative than abrupt. Academic research supplied depth. Large-company discovery supplied development discipline. Immuno-oncology leadership supplied systems. The startup supplied a place to combine them, along with the responsibility to finance every next step.

Apeximmune still has to demonstrate what its programs can do beyond preclinical models. Its disclosed ambition is clear: move AI-306 into clinical testing and continue developing antibodies against immune mechanisms its platform identifies. The scientific wager is that important brakes remain unaddressed. The organizational wager is that Lee’s team can repeatedly find, rank, and drug them.

There is something fitting about a company built around hidden suppression. Most of the work that determines a biotech’s fate is hidden too: the assay that gets repeated, the target that gets dropped, the manufacturing problem caught early, the careful decision to wait for better evidence. Lee has spent a career looking for consequential signals beneath noisy biology. Apeximmune is the largest expression yet of that habit.