Absci, a US company that uses artificial intelligence to design drugs, has reported the first human data for its experimental antibody shot for pattern hair loss1. The company said that in 32 healthy adults, some with pattern hair loss and some without, there were no serious side effects as of the data cutoff. It also said the drug stays in the body a long time, with an estimated half-life of at least 65 days1. The drug, called ABS-201, has not yet been shown to grow hair in people2.
What happened
On 24 June 2026, Absci announced early, or “interim”, results from the first stage of its first trial in people1. The trial is called HEADLINE. It is an early-stage study designed to check safety first and then look for signs that the drug works1. The first volunteers received the drug in December 20251. The study runs in Australia, at Sinclair Dermatology, a clinic led by dermatologist Dr. Rodney Sinclair1.
In this first stage, volunteers each got a single dose. The doses went up step by step across four groups: 150 mg, 450 mg, 900 mg and 1,800 mg, given into a vein1. Starting low and rising slowly is a standard way to check safety before moving to repeated doses.
Absci said the next stage has started. People with pattern hair loss, known medically as androgenetic alopecia, are now receiving more than one dose1.
The evidence so far
The new human data cover two things: safety and how long the drug lasts in the body. No serious adverse events were reported as of the data cutoff1. The estimated half-life, the time it takes for half the drug to clear the body, was at least 65 days1. Absci said this could mean patients would need only two or three injections over six months1. A review by a hair clinic noted that this schedule is still a development target, not a tested result2.
The idea behind the drug comes mostly from lab work. Prolactin is best known as a hormone made by the pituitary gland, but hair follicles also make it and carry its receptor2. In a 2006 lab study, exposing scalp follicles in a dish to high levels of prolactin slowed hair growth and pushed follicles early into catagen, the stage when a follicle shrinks2. ABS-201 is built to block the receptor that prolactin uses to send its signal, which is different from simply lowering prolactin levels2.
In December 2025, Absci released lab data from human scalp tissue kept alive outside the body1. The company said the antibody blocked the prolactin signal, kept follicles in their growing phase longer, raised growth signals called IGF1 and FGF7, and protected follicle stem cells from dying1. The work was led by researcher Ralf Paus, who said:
Our study provides the first evidence that antagonizing prolactin signaling with ABS-201 could open a radically new chapter in future AGA management.
That quote was reported in coverage of the announcement1. A related abstract presented at Cold Spring Harbor in May 2026 described six-day experiments on male scalp tissue in culture. It is lab evidence, not a hair-growth trial in people2.
What it does not show yet
The most important question is still open: does the shot grow hair in people? As of late September 2026, results from controlled tests of hair growth in people had not been reported2. The 32 volunteers in the first stage were healthy adults, and not all of them had hair loss1. A single dose in a small group can show early safety and drug levels. It cannot show whether hair grows, how much, or in whom.
Some other limits:
- The results come from a company announcement, not a peer-reviewed paper.
- Safety over many months of repeat dosing has not been reported.
- A blood test for prolactin is not an established way to predict who might respond to this antibody2.
- The drug is not approved and has no launch date2.
An analyst writing on Seeking Alpha described the coming efficacy readout as uncertain, pointing to mixed results from a competing drug that works the same way3.
Who is behind it
Absci is publicly traded and uses generative AI to create new drugs and biologics1. Shortly after the June data, the company raised $100 million by selling shares. Eli Lilly, a large US drugmaker, led the offering1. The money is meant for both the hair-loss program and a separate program in endometriosis, a painful condition in which tissue like the womb lining grows elsewhere1. Absci’s share price rose 36% afterwards, according to one hair-loss news site1.
Before that raise, the Seeking Alpha analyst put Absci’s cash at $125.7 million and flagged a high risk that the company would issue more shares3. The analyst said they held no position in the stock3.
Readers should also know where the coverage comes from. One source is a hair-loss news blog that follows new treatments1. Another is a review written by the medical director of a hair transplant clinic2.
How it fits the field
Common hair-loss treatments often act on DHT, a hormone linked to pattern hair loss. ABS-201 targets a separate pathway2. If that pathway matters, it could add an option for people whose current treatment does not suit them or helps only partly. The clinic review notes this could also be relevant to women, though response in any group has not been established2.
Absci is not alone. Hope Medicine, a Chinese company, is testing a similar prolactin-receptor-blocking shot called HMI-115. It licensed the drug from Bayer1. HMI-115 was first tested in people at the same Australian clinic in 2022 and finished a mid-stage trial in China in 20251. The Seeking Alpha analyst wrote that Absci’s trial aims to block more of the receptor than HMI-115 does3. Other hair-loss drug makers are further along: Veradermics and Pelage are both in late-stage trials1.
Absci has said the same approach might also help with gray hair and endometriosis3. In September 2026, the company pushed the expected start of its endometriosis trial to mid-2027, from an earlier forecast of late 20262. That change does not affect the hair-loss timeline.
What to watch next
Absci expects the first proof-of-concept data, meaning early signs of hair growth, in the second half of 20261. The company kept that guidance in August 20262. Fuller results covering 26 weeks of treatment are expected in early 20272. A larger 227-person mid-stage trial is expected to finish in July 2028, according to one hair-loss news site1.
The key things to look for in those results:
- whether people with hair loss grew measurably more hair than those given a dummy treatment;
- how many people responded, and whether results differ by age or sex;
- safety with repeated doses over months;
- whether the dosing schedule of a few shots a year holds up.
Biohack will follow the HEADLINE trial as results come in.
