Myricx Bio

A small building in London, doing chemistry the giants skipped

In a lab in central London, about thirty-five people are working on a part of the cancer drug that almost everybody else takes for granted. The antibody-drug conjugate - ADC for short - has three pieces: an antibody that finds the tumor, a linker that holds everything together, and a payload that does the killing. The industry spent a decade perfecting the first two. Myricx Bio went straight for the third.

The payload is the warhead. For years, nearly every approved ADC has carried a variation on the same two ideas: jam the cell's microtubules, or break its DNA through topoisomerase. They work, until they stop working. Tumors learn. Myricx is betting on a different mechanism entirely - one most of the field had filed under "interesting, but good luck drugging it."

When the obvious payloads run out of road

Here is the uncomfortable fact behind a booming field. ADCs are one of oncology's great success stories, but the warheads they carry come from a short, crowded shelf. Resistance is common. Cross-resistance - where a tumor that beats one payload shrugs off the next - is worse. A patient can cycle through several ADCs and meet the same molecule wearing a different costume each time.

The enzyme at the center of Myricx's answer is N-myristoyltransferase, or NMT. It performs a quiet bit of cellular housekeeping: attaching a fatty tag called a myristoyl group to certain proteins, which then go on to do jobs that cancer cells depend on. Block NMT and you don't poke at one pathway - you pull a thread that several of them hang from.

A chemist, a professor, and a biotech veteran walk into a spinout

Myricx was founded in 2019 - originally as Myricx Pharma - on science that came out of Imperial College London and the Francis Crick Institute. Professor Ed Tate, an authority on myristoylation and protein modification, supplied the biology. Andrew Bell, a chemistry PhD from the same department, supplied the molecules. Roberto Solari, who had helped found Astex Therapeutics and Heptares and spent years at GSK, supplied the inconvenient questions about whether any of it could become a company.

Their wager was specific. NMT inhibition had circled the cancer literature for years as a promising idea that never quite arrived as a drug. The team's insight was to stop trying to dose it as a standalone pill and instead bolt it onto an antibody - using the ADC to deliver a payload precisely where it was needed, and only there. The obscure mechanism became, suddenly, a lot more practical.

One platform, built around a single enzyme

What Myricx actually makes is a class of NMT-inhibitor payloads and the ADCs that carry them - shorthand: NMTi-ADCs. The antibody handles targeting, aimed at tumor-associated antigens that the field has already validated. The Myricx payload handles the killing, through a mechanism the tumor hasn't seen before.

Two properties matter most in the early data. The first is bystander activity: the payload doesn't only hit the cell the antibody docks onto, it spills into neighbors, which helps in tumors where antigen expression is uneven. The second is range - efficacy across a broad spread of antigen levels, including patient-derived models that other ADCs struggle with. In a field where a payload's reputation lives or dies on whether it works when the easy ones don't, that is the whole ballgame.

The data did the fundraising

Investors don't co-lead a £90m round on a novel mechanism out of politeness. Myricx reported that its initial NMTi-ADCs produced complete and durable tumor regressions, at well-tolerated doses, in multiple solid-tumor models that were refractory to topoisomerase-based ADCs - the standard the field measures against. The payloads showed bystander activity and held up across patient-derived xenograft organoid models spanning a range of antigen expression.

Push the new payload all the way to patients

The stated goal is unglamorous and exactly right: advance a proprietary pipeline of NMTi-ADCs through clinical proof of concept, against clinically validated targets, in cancers with serious unmet need. The money raised in 2024 has one job - get a genuinely new payload class out of the lab and into people, where the only data that ultimately counts gets made.

That is also where the difficulty sharpens. Preclinical regressions are necessary and not sufficient; plenty of beautiful mechanisms have faltered in the clinic. Myricx's task now is to prove that an idea which looked good on a slide, then good in a mouse, holds up in a human. The 2025 leadership build-out - a Boston CEO, expanded clinical and regulatory ranks - is the company assembling the people who actually run that gauntlet.

Back to the small building in London

Return to that lab. The thirty-five people are still there, still working on the part of the drug everyone else treats as settled. The difference is that the rest of the field is now watching. If NMT-inhibitor payloads do in patients what they've done in models, the short shelf of ADC warheads gets a new entry - and the tumors that currently win by outlasting the old payloads lose that advantage.

That is the wager Myricx Bio made in 2019 and re-upped with £90m in 2024: that the next chapter of cancer drugs is written not by a smarter antibody, but by a smarter warhead. The antibody finds the door. Myricx is betting it brought a better key. The clinic will tell us if the lock turns.

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