KX-826 (Pyrilutamide) From Phase 1 to Phase 3: What We Know Now
Published by AmpleLab Research
KX-826, also known as pyrilutamide, is a topical androgen receptor antagonist developed by Kintor Pharmaceutical (HKEX: 9939), a publicly listed biotech based in Suzhou, China. It's one of three topical antiandrogens currently in clinical development for pattern hair loss, alongside clascoterone (Breezula) and the unapproved research chemical RU58841. As of March 2026, KX-826 has completed a pivotal male Phase 3-stage trial and Kintor says it plans to seek approval in China, but the drug remains investigational and hasn't been approved anywhere. This article covers KX-826 specifically: the mechanism, its trial history across five years and two continents, and where the programme actually stands as of writing. For how it compares directly to RU58841, see our separate comparison article.
The Mechanism
KX-826 is a competitive androgen receptor antagonist. Rather than reducing DHT production the way finasteride and dutasteride do, it's intended to compete directly with both testosterone and DHT for the androgen receptor at the follicle, blocking androgen signalling at the follicle without reducing circulating androgen levels. Our article on DHT and the androgen pathway covers this receptor biology in depth.
Kintor has described the molecule as being designed for high receptor potency and rapid systemic clearance, aiming to keep the antiandrogen effect concentrated at the scalp. KX-826 is generally described in research-chemical literature as considerably more potent per molecule than RU58841, which is one reason it's typically formulated and studied at much lower concentrations (0.25-1% in most of its trials, against RU58841's typical 5% grey-market products). We'd flag that specific potency claim as coming from vendor literature rather than a peer-reviewed head-to-head comparison, so treat it as indicative rather than precise. Whether the lower concentration also means less systemic absorption in practice is a related but separate question, covered in more depth in our RU58841 comparison article.
Worth knowing for context: Kintor also runs a second, mechanistically different programme, GT20029, a topical androgen receptor degrader built on PROTAC technology. Rather than blocking the receptor, a degrader is designed to physically break it down within the cell. That's a genuinely different mechanism from KX-826, not a variant of it, and the two shouldn't be confused when reading Kintor's broader pipeline coverage.
The Full Trial History
KX-826 has been in clinical development since at least 2019, across parallel US and China trial programmes, at doses that have shifted considerably along the way.
The earliest registered human trial, testing single ascending topical doses in 40 healthy men with androgenetic alopecia, registered around 2019. Secondary reporting describes adverse events as mild, with contact dermatitis that healed quickly the main drug-related finding, and no severe adverse events. This predates the multiple-dose Phase 1 study below by roughly a year.
A dose-ascending safety, tolerability, and pharmacokinetic study in 40 healthy men, applying KX-826 daily for 14 days at 2.5mg, 5mg, 10mg, or 20mg against placebo, starting January 2020. Secondary reporting on this trial describes the adverse events as mild, with contact dermatitis the main drug-related adverse event, and blood concentrations of KX-826 as low. We haven't located a published paper with the full pharmacokinetic dataset behind that finding, so treat the "low systemic exposure" characterisation as a reported summary rather than an independently reviewable result.
120 men with androgenetic alopecia, randomised to 2.5mg twice daily, 5mg once daily, 5mg twice daily, or placebo, over 24 weeks, measuring target-area hair count against baseline and placebo. This is the trial that produced KX-826's most disappointing result to date: the 0.5% (5mg) twice-daily group improved by about 10 hairs/cm² from baseline at 24 weeks, but the reported improvement over placebo did not reach statistical significance. That's a genuinely mixed outcome, not something Kintor's later, more positive announcements should overshadow.
160 Chinese women with female pattern hair loss, randomised to 2.5mg once daily, 2.5mg twice daily, 5mg once daily, 5mg twice daily, or placebo, over 24 weeks. Reported results favoured the 5mg (0.5%) once-daily arm, with hair count improving by 11.39 hairs/cm² compared with placebo (both measured from baseline) at week 24, a difference reported as statistically significant (p=0.0087), visible from around week 12, with no serious adverse events reported. Kintor selected this dose and frequency to carry forward into female Phase 3 development.
A separate, earlier placebo-controlled Phase 3 trial testing 0.5% twice daily in roughly 740 Chinese men, with enrolment completed in March 2023. The registry still lists an estimated primary completion date of May 2024 and an "unknown" overall status, with no results currently posted. This is a genuinely different trial from the one below, and its outcome, positive, negative, or simply unreported, isn't publicly known as of writing.
This is Kintor's actual pivotal male trial, a Phase II/III seamless adaptive design testing 0.5% and 1.0% concentrations, both twice daily, against vehicle, with 666 men enrolled (222 per arm). First patient enrolled December 2024; full Phase III-stage enrolment completed July 2025, by which point the trial's own Phase II stage had already reached its primary endpoint. Topline Phase III-stage results, announced by Kintor in March 2026, reported both the 1.0% and 0.5% twice-daily groups met the primary endpoint with statistically significant, clinically meaningful improvement over vehicle. Kintor stated it plans to initiate an NDA submission for the 1.0% formulation with China's regulator "in the near term," without giving a specific target quarter in anything we've located.
A 52-week, open-label safety study across 16 Chinese centres, using 0.5% twice daily in men and women with AGA. The primary endpoint was the incidence of treatment-emergent adverse events, not efficacy. Kintor reported low overall adverse-event incidence, no deaths, and no drug-related sexual dysfunction, alongside positive hair-count signals at 52 weeks. Because this was open-label with no placebo comparator, its efficacy findings shouldn't be weighed the same way as a placebo-controlled pivotal trial, but the safety data over a full year of continuous use is a genuinely useful addition to the record.
Worth being clear about the scale of the overall male pivotal effort here: two separate large, placebo-controlled Phase 3-stage trials have run in China (740 and 666 patients respectively), plus a full year of open-label safety data in a third study. Only the 666-patient trial's efficacy result is currently public.
Worth noticing across this whole history: the concentration and dosing frequency tested has moved around a great deal, from percentage-based doses in the earliest trial, through 2.5mg, 5mg, 10mg, and 20mg doses across various once- and twice-daily regimens, to a head-to-head 0.5% vs 1.0% comparison in the pivotal trial that eventually reported the positive result. That's not inherently a red flag; dose-finding and formulation changes are normal parts of drug development, and testing two concentrations against each other in the same pivotal trial is a reasonably rigorous way to settle on a final one. But it does mean the earlier trials, including the 740-patient trial covered above, weren't run at the concentration that ultimately succeeded.
Where This Actually Stands
KX-826 is not approved by any regulator, anywhere, and is not available for purchase through any legitimate medical channel. Following the March 2026 pivotal trial result, Kintor has stated it plans to initiate a New Drug Application with China's National Medical Products Administration for the male indication "in the near term." No filing has been announced for the US or Europe, and no confirmed approval or launch date exists for any market. The female development programme is further behind, still working through Phase 3 following the positive Phase 2 signal covered above.
KX-826 is also sold by research-chemical suppliers outside any formal medical channel, marketed toward the same audience that uses RU58841. We don't cover dosing or sourcing for either compound here, in line with our usual approach to unapproved compounds.
Frequently Asked Questions
Has KX-826 actually been shown to work?
The evidence is mixed rather than uniformly positive. An earlier US Phase 2 trial in men showed improvement that didn't reach statistical significance over placebo. A China Phase 2 trial in women showed a statistically significant improvement over placebo at the selected dose. Kintor's pivotal China Phase 3-stage trial in men reportedly met its primary endpoint for both tested concentrations in March 2026, though full peer-reviewed results with complete methodology haven't been published yet.
Why has the tested concentration changed so much?
Earlier trials tested a range of doses (2.5mg to 20mg, in various once- and twice-daily combinations), and an earlier large Phase 3 trial used 0.5% twice daily. The pivotal trial that eventually reported a positive result tested 0.5% and 1.0% head-to-head against vehicle, and both met the primary endpoint, with Kintor now planning to move forward with the 1.0% formulation. Dose-finding across multiple trials is a normal part of drug development, though it does mean the earlier, larger trial wasn't run at the concentration Kintor is now taking forward.
Is KX-826 the same as GT20029?
No. Both are being developed by Kintor for hair loss, but they work differently. KX-826 is a receptor antagonist, it blocks the androgen receptor without destroying it. GT20029 is a PROTAC-based receptor degrader, designed to break the receptor down within the cell. They're separate compounds with separate trial programmes.
Selected Research
This article is provided for educational purposes and does not constitute medical advice. KX-826 (pyrilutamide) is an investigational drug not approved by any regulator and not available for purchase through any legitimate channel. AmpleLab products are cosmetic formulations, unrelated to KX-826, and are not intended to diagnose, treat, cure, or prevent any condition.
AmpleLab.