Seattle, WA, U.S.A. and Tokyo, Japan (September 27, 2010) - Otsuka Pharmaceutical Co., Ltd. and Acucela Inc. today announced that they have entered into a definitive agreement on September 24, 2010 to co-develop and co-promote OPA-6566, an adenosine A2a receptor agonist discovered and currently under development by Otsuka for the treatment of glaucoma, in the United States.

Under the agreement, Otsuka will contract Acucela to perform early clinical development of OPA-6566 in the United States and grant Acucela an opt-in right to co-develop and co-promote the compound. In the event and after Acucela exercises the opt-in right, Otsuka and Acucela will co-develop the compound sharing the cost incurred and co-promote the resulted product in the United States after regulatory approval. Upon Acucela exercising its opt-in right, Otsuka will receive a certain amount of pre-determined opt-in fee and milestone payments.

The compound OPA-6566 is currently under preclinical study, with clinical development scheduled to begin next year.

"Over the last few years, Acucela and Otsuka have built a strong strategic partnership to jointly pursue development efforts to deliver two innovative ophthalmologic drugs to patients - Acucela-discovered ACU-4429, being developed for dry age-related macular degeneration, and Otsuka-discovered Rebamipide ophthalmic suspension, being developed for dry eye," stated, Taro Iwamoto, Ph.D., president of Otsuka Pharmaceutical. "We are delighted to expand our working relationship with Acucela, and underline our new found resolve to develop OPA-6566 as a novel treatment for patients with glaucoma."

Acucela's chairman, president and chief executive officer, Ryo Kubota, M.D., Ph.D., commented, "We are pleased to further strengthen our partnership with Otsuka with this new agreement, which further broadens Acucela's portfolio of potential eye treatments for patients with blinding eye diseases and represents an important step forward in our growth strategy. The number of patients with glaucoma is expected to increase throughout the world and, with its novel mechanism of action, OPA-6566 has the potential to provide a new value not found in conventional glaucoma medications. We look forward to leveraging our deep understanding of glaucoma and clinical development expertise to advance OPA-6566 into human clinical trials."

About OPA-6566

OPA-6566 is a novel compound discovered by Ako Research Institute, Otsuka Pharmaceutical. The compound, an adenosine A2a receptor agonist, has a new mechanism of action not seen in conventional glaucoma medications. The compound has demonstrated the ability to lower intraocular pressure by stimulating aqueous humor outflow via trabecular meshwork through an activation of adenosine A2a receptor.

About Glaucoma

Glaucoma is a type of progressive or chronic optic neuropathy caused by intraocular pressure or by other factors of unknown origin. Persons affected with glaucoma experience gradual loss of vision over a long period of time. As the lost visual field cannot be recovered, continuous control of intraocular pressure is necessary for the rest of the patient's life. For this reason, safe drugs that lower intraocular pressure are needed.

In the United States, over three million people suffer from glaucoma, and this number is expected to increase dramatically as the population ages. Common treatments for preventing progression of visual field loss in patients diagnosed with glaucoma include drug therapy (beta blockers, prostaglandins, etc.), laser therapy and surgery, depending on the necessity and urgency of treatment.

About Otsuka Pharmaceutical Co., Ltd.

Founded in 1964, Otsuka Pharmaceutical Co., Ltd. is a global healthcare company with the corporate philosophy: 'Otsuka-people creating new products for better health worldwide.' Otsuka researches, develops, manufactures and markets innovative and original products, with a focus on pharmaceutical products for the treatment of diseases and consumer products for the maintenance of everyday health. Otsuka is committed to being a corporation that creates global value, adhering to the high ethical standards required of a company involved in human health and life, maintaining a dynamic corporate culture, and working in harmony with local communities and the natural environment.
Otsuka Pharmaceutical Co., Ltd. is a wholly owned subsidiary of Otsuka Holdings Co., Ltd., the holding company for the Otsuka Group. The Otsuka Group comprises 145 companies and employs approximately 39,000 people in 23 countries and regions worldwide. Otsuka and its consolidated subsidiaries earned JPY 1,084.2 billion (approx. US $11.7 billion^*) in annual revenues in fiscal 2009.

• * Exchange rate as of March 31, 2010.

About Acucela Inc.

Acucela Inc. is a clinical-stage biotechnology company focused on leveraging promising science in visual cycle modulation (VCM) to develop new methods for treating blinding eye diseases that affect tens of millions of people worldwide. The company's orally-delivered VCM therapies, which selectively target cells within the retina to protect visual acuity, have the potential to be used to treat several devastating eye diseases, including dry age-related macular degeneration (AMD), retinopathy of prematurity, Stargardt disease and diabetic retinopathy. Acucela is also developing, with Otsuka Pharmaceutical, Rebamipide ophthalmic suspension for dry eye and OPA-6566 for glaucoma. Acucela was founded by Ryo Kubota, M.D., Ph.D., a pioneer in the ophthalmology field and the discoverer of the gene that causes glaucoma. For more information, please visit www.Acucela.com.