Kintor Announces Update on KX-826 (Pyrilutamide) for Hair Loss

Kintor Pharmaceutical Ltd. recently announced the US phase II clinical trial results for its androgen receptor antagonist, pyrilutamide. This topical androgen receptor-blocking drug, also known as KX-826, is being developed for the treatment of male and female androgenetic alopecia (pattern hair loss).

What Is Pyrilutamide (KX-826) Used for?

Pyrilutamide is being developed for two indications: androgenetic alopecia and acne vulgaris. It’s currently completing clinical trial testing for male androgenetic alopecia in China and the United States.

Pyrilutamide is only in clinical trials for female androgenetic alopecia and acne vulgaris in China at this time, but Kintor plans to move forward with trials in the USA, too. As of May 2023, Kintor has submitted an investigational new drug application but has yet to start clinical trials for its acne indication in the United States. (1)

Kintor’s Latest Clinical Trial Results (Updated July 2023)

In May 2023, Kintor announced that the American phase II clinical trial testing of pyrilutamide on men with androgenic alopecia had been successful, demonstrating good efficacy and safety. This study was a randomized, double-blind, placebo-controlled, parallel-group, phase II clinical trial involving 123 participants. All of the men had been classified as having moderate androgenetic alopecia symptoms (defined as Norwood-Hamilton classifications IIIv, IV, or V). (2)

Three different options (and two controls) were tested during this clinical trial:

• Pyrilutamide 2.5 milligrams (0.25% concentration) applied once daily
• Pyrilutamide 5 milligrams (0.5% concentration) applied once daily
• Pyrilutamide 5 milligrams (0.5% concentration) applied twice daily

The study reported that applying 0.5% pyrilutamide twice a day produced the best improvements in hair growth, increasing hair count by 10 hairs per cm² from baseline after 24 weeks of treatment. This was considered to be statistically significant. With no reported serious adverse events, Kintor intends to move forward with phase III clinical trials focusing on this twice-a-day 0.5% dose of KX-826. (2)

Kintor Phase II Clinical Trial Results in China

At the end of 2022, Kintor released its phase II clinical trial results for the treatment of male androgenetic alopecia in China. The results were published in press releases and a poster created for the Annual Meeting of the Chinese Hair Research Society. (3-6)

This poster reported that there were 120 Chinese participants in this trial. Like in the American phase II clinical trial, all of the participants were men who had pattern hair loss symptoms classified as moderate (Norwood-Hamilton classifications IIIv, IV, or V). The study assessed KX-826’s effectiveness at two different concentrations: 0.25% and 0.5%. The medication was applied either once daily (for 0.5% pyrilutamide) or twice daily (for both 0.25% and 0.5% pyrilutamide). (3-6)

Ultimately, men who applied 5 milligrams of pyrilutamide at a 0.5% concentration twice a day were shown to have the best improvements in hair growth. Hair count in this group was reported to improve by 22.73 hairs per cm² from baseline after 24 consecutive weeks of treatment, which was 15.34 hairs per cm² better than the hair growth shown in the control group. (3-6)

Kintor is now advancing with its phase III pyrilutamide trial, which is focused on testing twice-a-day 0.5% dosing of KX-826 on Chinese men with androgenetic alopecia. If you’re based in China and interested in joining this study, you’re out of luck. As of March 2023, Kintor completed patient enrollment for this clinical trial. (1,12)

However, in July 2023, Kintor announced that it will be conducting a second phase III pyrilutamide trial, which is designed as a 52-week, 16-center, safety study. This clinical trial will recruit 270 male and female participants with pattern hair loss. On July 19, 2023, Kintor announced that the study’s first patient had been recruited. The trial is believed to still be recruiting participants. (13)

Kintor US vs. China Phase II Clinical Trial Results

While both American and Chinese phase II clinical trials for KX-826 were considered to be successful as they produced statistically significant results, it’s notable that the Chinese phase II trial reported an improvement of 22.73 hairs per cm², while the American phase II trial reported an improvement of just 10 hairs per cm². These results imply that their hair loss treatment was more than twice as effective in their Chinese participants, though it is still unclear why this has occurred. It will be interesting to see if these trends continue in their phase III hair loss trials. (2-6)

Kintor has already started moving forward with phase III clinical trials testing pyrilutamide for hair loss in China and also plans to do so in the United States. The recommended dosing in both trials will likely be the same, focusing on the twice-a-day application of 0.5% KX-826.

Kintor Phase II Female Clinical Trial Results in China

At the moment, Kintor is only running female androgenetic alopecia trials in China. In March 2022, they announced that they had completed patient enrollment (of 160 women) for their phase II KX-826 clinical trial. In December 2022, they announced that the clinical trial had been completed successfully. (10)

The female KX-826 clinical trial was a 24-week, multicenter, randomized, double-blind, placebo-controlled study that assessed four treatment groups and two control groups. All of the women had been classified as having moderate to severe female pattern hair loss symptoms (defined as grade D3, D4, D5, or D6 on the Savin Density Scale). (11)

The four treatment groups assessed in this phase II clinical trial were:

• Pyrilutamide 2.5 milligrams (0.25% concentration) applied once daily
• Pyrilutamide 2.5 milligrams (0.25% concentration) applied twice daily
• Pyrilutamide 5 milligrams (0.5% concentration) applied once daily
• Pyrilutamide 5 milligrams (0.5% concentration) applied twice daily

The study reported that applying 0.5% pyrilutamide once a day produced the best improvements in hair growth, increasing hair count by 11.39 hairs per cm² from baseline after 24 weeks of treatment. Notably, improvements in hair regrowth were noticeable by week 12. (11)

This was considered to be statistically significant. With no reported serious adverse events, Kintor intends to move forward with phase III clinical trials focusing on this once-a-day 0.5% dose of KX-826 for women with pattern hair loss. It is unclear if the current phase III safety study that is enrolling female participants is assessing this KX-826 dose. (11,13)

How Does KX-826 Work for Hair Loss?

KX-826 is an androgen receptor blocker that works by targeting androgen receptors directly. It’s essentially a type of dihydrotestosterone (DHT) blocker. However, it’s unique compared to other DHT blockers, like finasteride and dutasteride, that are already being used as treatments for androgenetic alopecia. Rather than targeting androgen receptors, finasteride and dutasteride function as DHT blockers by targeting the 5-α-reductase enzyme that converts testosterone into DHT. (7)

Dutasteride and finasteride are typically used as oral medications, and both can cause systemic side effects in some patients. (7) Since pyrilutamide is a topical medication, it may be a better alternative for people who cannot safely take oral finasteride or dutasteride for the treatment of pattern hair loss. KX-826 also presents a unique treatment option for women as no DHT blockers are currently approved for the treatment of female pattern hair loss.

Is Pyrilutamide Topical?

Pyrilutamide is exclusively meant to be used as a topical treatment for pattern hair loss and acne. This puts it in the same category as the hair loss treatment Breezula® (also known as clascoterone and CB-03-01), a topical androgen receptor antagonist being developed by Cosmo Pharmaceuticals. Breezula® is currently in phase III clinical trials for male pattern hair loss. It’s already approved as an acne treatment under the brand name Winlevi®. (8)

KX-826 vs. GT20029 

Pyrilutamide is also similar to another Kintor Pharmaceutical product, GT20029. This topical drug is also being developed for androgenetic alopecia and acne vulgaris. However, GT20029 is not an androgen receptor antagonist – it’s an androgen receptor degrader. (9) 

Kintor has said GT20029 is classed as a proteolysis targeting chimera – also known as an AR-PROTAC drug. This medication has successfully completed phase I clinical trials for acne vulgaris and androgenetic alopecia in the United States and China, and Kintor is currently moving forward with phase II clinical trials. (9)