The Seoul lab that decided cancer's "undruggable" targets were just the ones nobody had been stubborn enough to drug.
Filed from Seoul - nine people, four cancer programs, and one drug that left the bench for the clinic in under a year.
In March 2025, a drug called AD1208 began moving from a Seoul laboratory into people. The trial enrolls patients with advanced solid tumors who have run out of better options. The drug is a MASTL kinase inhibitor - a sentence that means very little to most of the planet and a great deal to the roughly nine people at Avelos Therapeutics, who have spent four years getting it there.
Avelos is not large. It is not loud. It has no consumer app, no glossy keynote, no waitlist. What it has is a thesis about how to kill cancer cells that other companies wrote off as too hard, and a clinical-stage molecule that suggests the thesis might be right. For a biotech founded in 2021 with a headcount in the single digits, that is an unusual place to be standing.
Above: The kind of sentence biotech CEOs say at every funding round. The difference is whether there is a trial number attached. Here there is one - NCT06911333.
Drug discovery has a quiet, awkward secret: a lot of the proteins that drive cancer are considered "undruggable." Not because they don't matter - they matter enormously - but because they have no convenient pocket for a small molecule to grab, or because hitting them breaks healthy cells too. For decades the field politely walked around them.
Avelos walked toward them, using an idea called synthetic lethality. The logic is almost mischievous: instead of attacking a tumor head-on, you find a second weakness that only matters because the cancer already carries the first. Knock out gene B, and a healthy cell shrugs. Knock out gene B in a cell already broken at gene A, and it cannot survive. The cancer's own defect becomes the trap.
The company concentrates on three connected systems - synthetic lethality, the DNA damage response (DDR), and cell-cycle regulation. These are the machinery a cancer cell uses to copy itself and repair the damage it does along the way. Jam that machinery in the right place, and the cell tears itself apart.
Translation for the rest of us: "undruggable" usually means "nobody has managed it yet." Avelos treats it as a to-do list.
In September 2021, three people who had spent their careers inside big pharma and Korea's national drug-discovery apparatus decided to build something small enough to take real risks. The bet was specific: that the synthetic-lethality wave sweeping global oncology could be ridden from Seoul, with first-in-class chemistry rather than fast-follower copies.
Came from Korea's National OncoVenture and Merck & Co. Sets the synthetic-lethality strategy and carries the "leader in the field" ambition.
Ex-Bayer Healthcare and PTC Therapeutics. Joined as CTO, promoted to Co-CEO in January 2024 as the science moved toward the clinic.
Thirty-plus years in drug discovery and development. Runs business development, partnerships, and the path toward technology transfer.
Resume math: Merck, Bayer, and PTC Therapeutics on the founder roster - and a total headcount you could brief in a single email.
A platform thesis is nice. A molecule in a patient is better. Avelos has both - a four-program pipeline anchored by a lead drug that is genuinely rare in the world.
A first-in-class oral MASTL kinase inhibitor. It disrupts mitosis and the DNA damage response, aimed at colon, stomach, breast, ovarian and prostate cancers. Preclinical data went to AACR 2024; a Phase 1/2a trial (NCT06911333) began enrolling in March 2025.
Targets tumors with homologous recombination deficiency (HRD) and aims to get around PARP-inhibitor resistance - a wall a lot of cancer patients eventually hit. Development-candidate and toxicology work sit in the 2024-2025 window.
Two additional early DNA damage response programs round the pipeline out to four, all built on the same biomarker-driven synthetic-lethality platform rather than four unrelated bets.
On MASTL: it stands for "microtubule-associated serine/threonine kinase-like." Very few companies anywhere have a clinical-stage MASTL inhibitor. Avelos has one.
Three pharma and national-oncology veterans incorporate in Seoul around a synthetic-lethality and DNA-damage-response platform.
SV Investment, Mirae Asset, Quad, Timefolio, UTC and Mirae Asset Capital back the early platform. A UK research collaboration is referenced for a first-of-its-kind program.
The science leans toward the clinic; the CTO is promoted to co-lead the company.
AD1208 preclinical results are presented at AACR 2024. Days apart, a Series B led by Stassets Investment pushes total funding past KRW 30 billion.
A Phase 1/2a trial in advanced and metastatic solid tumors (NCT06911333) starts enrolling - first-in-human for the lead program.
Conviction in early biotech is hard to measure. One imperfect proxy: whether the people who already paid in are willing to pay in again, and whether new names join them. At Avelos, the answer to both has been yes - across seed, Series A, and a 2024 Series B that more than tripled the company's earlier total.
Reading the bars: the jump from 12 to 30 is the Series B - the round where backers decided the platform had earned a clinic-bound drug.
The Series B cap table reads like a vote of confidence with footnotes: lead investor Stassets Investment, new money from LSK Investment, Medytox Venture Investment, Shinhan Capital and Heungkuk Securities, and returning believers SV Investment, Mirae Asset Venture Investment, Quad Investment Management and Timefolio Capital. The stated next steps - Korean research partnerships, global technology transfer, and eventually a KOSDAQ listing once two substances reach clinical stage - are the kind of plans you only announce when the science is cooperating.
Avelos states its purpose plainly: develop biomarker-driven small molecules that exploit synthetic lethality, the DNA damage response, and cell-cycle vulnerabilities to attack cancer targets long considered undruggable. The "biomarker-driven" part is the discipline - the company wants to know in advance which patients a drug should help, not discover it after the fact.
The ambition behind the mission is less modest. The founders want Avelos to be a leader in synthetic lethality, not a regional participant - which is why the roadmap keeps mentioning global technology transfer and worldwide clinical use. It is a large goal for a small company. It is also exactly the kind of goal that a first-in-class MASTL inhibitor in the clinic makes slightly less absurd.
From an AACR poster (April 2024) to a first-in-human trial (March 2025). Fast, for a field that measures progress in decades.
People on the team. The founder resumes - Merck, Bayer, PTC Therapeutics - outnumber the rest of the company.
Synthetic lethality in one line: hit a second gene so a cell already broken in one way simply can't survive.
AVS1002 aims squarely at PARP-inhibitor resistance - the wall many HRD cancer patients eventually run into.
Return to March 2025. AD1208 is no longer a slide or a poster or a hopeful line in a funding announcement. It is in patients - people with advanced solid tumors, the ones for whom "undruggable" was never an abstraction. The molecule that a nine-person Seoul team built to exploit a defect in cancer's repair machinery is now being measured against the disease itself.
That is the change. Four years ago, Avelos was a thesis about targets everyone else avoided. Today it is a company with a clinical-stage drug, a biomarker-driven pipeline, and a cap table that keeps re-upping. The trial will say what it says - that is what trials are for. But the question Avelos formed around has already shifted from "can these targets be drugged at all" to "how well." For a label that used to read "undruggable," that is a meaningful edit.