Sosei Heptares Announces Submission of New Drug Application in Japan for Daridorexant (ACT-541468), a Dual Orexin Receptor Antagonist for the Treatment of Insomnia

Sosei Heptares Announces Submission of New Drug Application in Japan for Daridorexant (ACT-541468),
a Dual Orexin Receptor Antagonist for the Treatment of Insomnia

• NDA includes robust data from a Phase 3 trial that demonstrated efficacy of daridorexant on improving Total Sleep Time and Latency for Sleep Onset, while maintaining a favorable safety profile
• Sosei Heptares to receive JPY 1.5 billion milestone revenue in relation to the submission

Tokyo, Japan and Cambridge, UK, 31 October 2023 – Sosei Group Corporation (“Sosei Heptares” or “the Company”; TSE: 4565) announces that Idorsia Pharmaceuticals Japan Ltd. (“Idorsia Japan”), a Sosei Group company, has submitted a New Drug Application (“NDA”) to the Japanese Pharmaceuticals and Medical Devices Agency (“PMDA”) for the approval of daridorexant (ACT-541468), a dual orexin receptor antagonist which has been co-developed with Mochida Pharmaceutical Co., Ltd. ("Mochida”), for the treatment of adult patients with insomnia.

The NDA is supported by positive results of a randomized, double-blind, placebo-controlled Phase 3 study in Japan to investigate the efficacy and safety of daridorexant. The study met both primary and secondary efficacy endpoints. Daridorexant significantly improved subjective Total Sleep Time (“sTST”), a primary endpoint defined as the change from baseline compared to placebo at 28 days (p<0.001 for 50 mg, p=0.042 for 25 mg). Daridorexant also significantly improved sleep onset as measured by a decrease in subjective Latency for Sleep Onset (“sLSO”), a primary endpoint defined as the change from baseline compared to placebo at 28 days (p<0.001 for 50 mg, p=0.006 for 25 mg). The rate of adverse events was comparable between placebo and daridorexant at both treatment doses. Treatment-emergent adverse events (“TEAEs”) during the double-blind study period were reported in 23.5% and 22.7% of the patients treated with 50 mg and 25 mg daridorexant, respectively (24.4% for placebo).

Sosei Heptares gained Japan and Asia-Pacific (ex-China) rights to daridorexant from Idorsia Pharmaceuticals Ltd (Allschwil, Switzerland) in July 2023 in the context of its acquisition of Idorsia Japan and Idorsia Pharmaceuticals Korea Co., Ltd. Daridorexant was approved in the US and Europe in January and April 2022, respectively, and is marketed by Idorsia in these and other approved territories as QUVIVIQ™. In December 2019, Mochida and Idorsia Pharmaceuticals Ltd entered into an exclusive license agreement for the co-development and co-marketing of daridorexant for insomnia and related disorders in Japan. Under the agreement, Mochida and Idorsia Japan have jointly developed daridorexant and plan to co-market daridorexant pending Idorsia Japan receiving Japanese PMDA approval.

In relation to the filing of this NDA, Sosei Heptares will receive JPY 1.5 billion (US$10 million*). The milestone receipt will be recognized as revenue in the fourth quarter of the financial year ending 31 December 2023.

* USD1 = JPY149.86

Makoto Uchiyama, M.D., Ph.D., medical advisor of the Japanese Phase 3 study, Director of Tokyo Adachi Hospital, Visiting Professor of Nihon University, and Visiting Professor of Toho University, commented: “Insomnia is highly prevalent in Japan and is recognized as an important national health issue. Patients with insomnia have trouble falling or staying asleep, as well as waking up earlier than desired, all of which lead to detrimental effects on both physical and mental health. Daridorexant is the first drug for a decade to have been clinically investigated in more than 100 centers in Japan and showed marked positive results in the studies. The Japanese Phase 3 trial showed that daridorexant increased total sleep time and shortened sleep latency in patients with insomnia without marked hangover symptoms the next morning, which clearly indicates its potency to improve core symptoms of insomnia. Such a promising outcome was likely due to the unique characteristics of the drug, a dual orexin receptor antagonist with an optimal elimination half-life.”

Satoshi Tanaka, Dr Med Sci., President of Idorsia Pharmaceuticals Japan (a Sosei Group company), and Executive Officer and Executive Vice President of Sosei Heptares, added: “The team has worked rapidly to analyze the data and prepare the dossier for the PMDA so that we can bring daridorexant to patients as soon as possible. We will now work together with the authorities through the regulatory process, and in parallel, prepare the scientific publication and the commercial launch of 10, 25 and 50 mg tablets, which we hope to see in the second half of 2024. Together with the development partner Mochida, the whole team is eager to rapidly make daridorexant available to Japanese patients with insomnia.”

QUVIVIQ™ is a registered trademark of Idorsia Ltd.