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Feb 17, 2020

Chugai Receives Orphan Drug Designation for RG6042 in Huntington's Disease from the MHLW

  • RG6042 is expected to delay or slow progression of Huntington’s disease as potentially the first disease-modifying drug for the hereditary disorder
  • The global phase III clinical study is currently ongoing

TOKYO, February 17, 2020 -- Chugai Pharmaceutical Co., Ltd. (TOKYO: 4519) announced that the Ministry of Health, Labour and Welfare (MHLW) has designated the company’s investigational medicine RG6042 as an orphan drug for the expected treatment of Huntington's disease. RG6042 is designed to reduce production of mutant huntingtin protein (mHTT), a protein generated from the genes responsible for Huntington's disease. The global phase III clinical study (GENERATION HD1) is currently ongoing.

Huntington's disease is designated as an intractable disease in Japan, and only symptomatic treatment is available for this disease. In this high unmet medical need, patients with this hereditary disorder are in need of potential new treatments” said Dr. Yasushi Ito, Chugai’s Executive Vice President, Co-Head of Project & Lifecycle Management Unit. “We continue the ongoing clinical study in cooperation with Roche to deliver RG6042 to patients with Huntington's disease, as the first disease-modifying drug.”

About RG6042
RG6042 (formerly known as IONIS-HTTRx) is an antisense oligonucleotide that targets human huntingtin messenger ribonucleic acid (HTT mRNA), designed to reduce the production of mHTT, which is believed to be the underlying cause of Huntington's disease. It is being developed as a disease-modifying drug for Huntington's disease and expected to delay or slow disease progression.1 RG6042 was designated as an orphan drug for the treatment of Huntington's disease in Europe and the U.S. in May and December 2015, respectively. In addition, the European Medicines Agency (EMA) granted PRIME (PRIority MEdicines) designation for the drug for the treatment of people with Huntington’s disease in 2018.

About Huntington's Disease
Huntington's disease is a hereditary disorder accompanied by involuntary movements, mainly choreic movements, in addition to psychiatric symptoms and cognitive changes.2 It is considered to be caused by accumulation of mHTT translated from mutant huntingtin genes with an expanded CAG repeat.3 Patients with Huntington's disease usually receive symptomatic treatment for involuntary movements and psychiatric symptoms because no definitive therapy is available for the disease. There are approximately 900 patients in Japan, based on the number of recipients with grant cards for medical expenses for the treatment of designated intractable diseases issued in 2017.4 The prevalence is expected to be 0.7 per 0.1 million population.2

About orphan drugs
Based on Pharmaceuticals and Medical Devices Law, orphan drugs are designated by the Minister of Health, Labour and Welfare and granted priority review. The designation criteria are as follows: The number of patients who may use the drug is less than 50,000 in Japan; The drug is indicated for the treatment of serious diseases and there is a significant medical value such as no alternative appropriate drug or treatment, or high efficacy or safety expected compared to existing products; there is a theoretical rationale for using the product for the targeted disease and the development plan is reasonable.


  1. Sarah J. Tabrizi, et al. Targeting Huntingtin Expression in Patients with Huntington’s Disease. N Engl J Med 2019; 380:2307-2316
  2. Japan Intractable Diseases Information Center: Available from: Accessed February 2020 (Japanese only)
  3. Walker FO. Huntington's disease. Lancet 2007; 369 (9557): 218-28
  4. The Number of Recipients with Grant Cards for Medical Expenses for the Treatment (of Designated Intractable Diseases) by Disease and Prefecture; Public Health Administration Report by MHLW (at the end of 2017): Available from: Accessed February 2020 (Japanese only)


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