Catherine
Sabatos-Peyton

Catherine Sabatos-Peyton runs Larkspur Biosciences, a Cambridge company built around a contrarian idea: stop chasing cancer at the surface and go after the genes that keep tumors alive. Most immunotherapy works by waking up the immune system from the outside. Larkspur designs small molecules that take away the tumor's hiding spots from the inside. The lead drug, LRK-4189, is a first-in-class degrader of a protein called PIP4K2C. In December 2025 it went into its first human being.

That moment was a long time coming. As a PhD student at Harvard, Sabatos-Peyton was part of the team that first described TIM-3 - a protein that is now a household name in cancer immunology and a regulator of leukemic stem cells in acute myeloid leukemia and myelodysplastic syndrome. She did not stop at describing it. She spent the next two decades turning that early discovery into a clinical reality.

At the biotech CoStim, she led the discovery of the first-in-class anti-TIM-3 antibody. Its name is sabatolimab. Read it slowly: the molecule carries the first half of her surname. It is a rare thing for a scientist to see their own work labeled with a fragment of their name and then walk it from a petri dish into Phase 2 and Phase 3 trials. She did both.

Then, in 2021, she did the harder thing. She left the world's biggest pharmaceutical research engine - the Novartis Institutes for BioMedical Research, where she had spent seven years and ran the Immune Modulation group - and took the CEO chair at a company that did not yet exist in the public eye. Larkspur launched in May 2023 with $35.5 million in seed and Series A money and a founding bench most CEOs would envy.

The founders read like a syllabus of modern cancer biology: Lewis Cantley, who discovered the PI3K signaling pathway; Nathanael Gray, a master of targeted small molecules; and Vijay Kuchroo, an immunologist whose lab has shaped how the field thinks about T cells. Sabatos-Peyton's job was to turn three brilliant ideas into one company with a clinic-bound drug. By late 2025, she had.

She leads with an all-female executive team - a chief scientific officer who spent twenty years running medicinal chemistry at GSK, and an EVP of biology pulled from the same world of translational immunology. In a sector where the corner office still skews heavily male, Larkspur is quietly an outlier, and Sabatos-Peyton does not make a speech about it. The work speaks.

Her own training was unusually wide before it became deep. She started at Fordham with a biology degree, then won a Fulbright to Oxford to study how the immune system turns on the body in autoimmune disease. Only after that did she land at Harvard for a PhD in immunology, with postdoctoral and research fellowships at UCSF and the University of Bristol stitched in along the way. By the time she joined industry, she had seen the immune system from the angle of disease, of basic biology, and of two different national research cultures.

That breadth is the through-line of how she talks about cancer. She does not pitch a single magic bullet. In interviews going back to her Novartis years, she has been consistent that the future of the field belongs to combinations - antibody with antibody, targeted therapy with immunotherapy, antibodies paired with CAR T cells or vaccines. The point, she argues, is durability: getting responses that last, in patients who have run out of options. Larkspur is her attempt to add a new tool to that combination toolbox, one that works on the tumor from the inside rather than the immune system from the outside.

The wider field has taken note. In 2024 she was named a Fellow of the Termeer Institute, the Cambridge organization built to support first-time biotech CEOs and named for the late industry figure Henri Termeer. It is a recognition reserved for leaders making the same leap she did: from running science to running a company. The distinction is not cosmetic. Translating deep expertise in a single protein into the messy, capital-hungry, people-heavy work of building a company is where most scientist-founders stumble. Sabatos-Peyton spent two decades earning the credibility, and then spent it deliberately.

What she has not done is stray from the problem she has chased since graduate school. The names change - TIM-3, sabatolimab, PIP4K2C, LRK-4189 - but the question underneath is the same one she helped open in a Harvard lab: how does cancer dodge the immune system, and what would it take to stop it? Most careers wander. Hers reads like a single, stubborn sentence that took twenty-some years to finish.