HK inno.N is advancing into a head-to-head phase 3 clinical trial to challenge Zoetis’ Apoquel, a market-leading treatment for atopic dermatitis in dogs. The Korean pharmaceutical company announced on Wednesday that it had received regulatory approval from the Animal and Plant Quarantine Agency to begin late-stage testing of its next-generation JAK1 inhibitor, IN-115314.
IN-115314 is an oral small molecule therapy developed to treat chronic skin inflammation and itching caused by eczema in dogs. The trial will be conducted across approximately 10 veterinary hospitals in South Korea. It will directly compare the efficacy and safety of IN-115314 against Apoquel, Zoetis’ oclacitinib-based therapy that has dominated the market since its launch in 2013.
While HK inno.N has not disclosed detailed information about the trial design due to an ongoing patent application related to the dosing schedule, the company emphasized its scientific confidence in IN-115314’s performance.
Unlike oclacitinib, which affects multiple Janus kinase (JAK) enzymes despite targeting JAK1, IN-115314 was designed for stronger selectivity. It focuses specifically on JAK1, which plays a key role in inflammatory signaling, while sparing JAK2, which is essential for blood cell production. This selective targeting could reduce the risk of side effects and allow for more flexible dosing, according to the company.
A study published on May 7 in the British Journal of Pharmacology supports these claims. Researchers reported that IN-115314 has higher JAK1 selectivity than oclacitinib and could be administered at higher doses without triggering JAK2-related side effects such as immunosuppression or elevated cholesterol levels.
In lab tests using canine blood cells, IN-115314 demonstrated 6.5 times greater potency on the JAK1–STAT3 pathway compared to Apoquel. Its JAK1-to-JAK2 selectivity ratio was 80 to 1—roughly four times greater than that of Apoquel. Additionally, while Apoquel showed a 1.6-fold increase in systemic exposure after one week of use, IN-115314 did not accumulate in the body, even at the highest tested dose.
Pharmacodynamic studies further confirmed the drug’s potential. At a dosage of 0.9 mg/kg, IN-115314 reduced IL-6-induced pSTAT3 activity in CD4+ lymphocytes by 83%, nearly double the reduction achieved by Apoquel.
Though still under investigation, HK inno.N is optimistic about IN-115314’s future. In a statement, the company compared the drug’s potential to that of its successful acid reflux treatment, K-CAB (tegoprazan), saying it hopes IN-115314 will “lead a new chapter in pet pharmaceuticals.” The company is also developing a topical form of the drug for human use, which received phase 2 approval in Korea this March.
Despite the growing competition, Apoquel remains a dominant player in the market. In 2024, it generated $1.08 billion in global sales and contributed to Zoetis’ $9.2 billion in annual revenue. Since its approval, the drug has been used in more than 91 million dogs worldwide.
A February safety review based on data from U.S. and European trials, independent studies, and post-market surveillance found no new safety concerns, even with long-term or lifelong use. The most commonly reported side effects—diarrhea, lethargy, and anorexia—remain rare, with an overall incidence rate of just 0.025%. A separate study involving 660 dogs found no increase in tumor risk. Researchers also noted that switching to once-daily dosing after two weeks helps minimize unwanted JAK2 inhibition.
Zoetis released a chewable version of Apoquel in 2023 to improve treatment compliance. However, long-term safety data for the new formulation are still being reviewed. Meanwhile, Elanco Animal Health entered the market in September 2024 with Zenrelia (ilunocitinib), a nonselective JAK inhibitor that carries a boxed warning for infection risk.
HK inno.N’s challenge signals a new phase of competition in the canine dermatology field, as companies aim to balance effectiveness with safety in treating one of the most common skin conditions in pets.
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