Daiichi Sankyo Initiates Phase 2 Trial to Evaluate Pexidartinib in Japanese Patients with TGCT

Tokyo, Japan – (April 9, 2021) – Daiichi Sankyo Company, Limited (hereafter, Daiichi Sankyo) today
announced that the first patient was dosed in a phase 2 study to evaluate the safety and efficacy of
pexidartinib, a CSF-1R inhibitor, in Japanese patients with symptomatic tenosynovial giant cell tumor
(TGCT) associated with severe morbidity or functional limitation and not amenable to improvement
with surgery.
TGCT, also referred to as pigmented villonodular synovitis (PVNS) or giant cell tumor of the tendon
sheath (GCT-TS), is a rare, typically non-malignant tumor that can be locally aggressive. TGCT affects
the synovium-lined joints, bursae and tendon sheaths, resulting in reduced mobility in the affected joint
or limb.1,2,3 For most patients, the current standard of care for TGCT is surgery; however, in more
severe cases, the tumor may be difficult to remove and/or may not improve with surgery.4 Multiple
surgeries can lead to significant joint damage, debilitating functional impairments, and reduced quality
of life, and amputation may be considered.4,5
“We are committed to continuing to explore the clinical benefit of pexidartinib in patients with TGCT,
a disease which can be associated with severe morbidity, functional limitations and may not be
amenable to improvement with surgery,” said Wataru Takasaki, PhD, Executive Officer, Head of R&D
Division in Japan, Daiichi Sankyo. “This study will further serve to inform our development path
forward in Japan and provide additional research insights to better understand this debilitating disease
and the role pexidartinib may potentially play in Japanese patients with TGCT who are in need of
alternative treatment options.”
About the Study
This phase 2, multicenter, two-part, open-label, single-arm study will evaluate the safety and efficacy of
pexidartinib in Japanese patients with symptomatic TGCT associated with severe morbidity or
functional limitation and not amenable to improvement with surgery.
Approximately 18 patients will be enrolled into the two-part study. In the first part, pexidartinib 800
mg/day (400 mg twice a day on an empty stomach) will be administered to evaluate the tolerability and
pharmacokinetics of pexidartinib to determine the initiation of the second part of the study. In the
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second part, pexidartinib 800 mg/day (400 mg twice a day on an empty stomach) will be administered
and efficacy, safety, and pharmacokinetics of pexidartinib will be evaluated.
The primary trial endpoints are dose-limiting toxicity, an analysis of pharmacokinetics and objective
response rate (ORR), assessed by RECIST Version 1.1. Key secondary endpoints include ORR by
tumor volume score, range of motion, patient reported outcomes, and treatment-emergent adverse
events.
The study will enroll patients at sites in Japan. For more information visit ClinicalTrials.gov
(NCT04703322) and the Japan Registry of Clinical Trials (JRCT ID: jRCT2041200074).
About TGCT (PVNS/GCT-TS)
TGCT, also referred to as pigmented villonodular synovitis (PVNS) or giant cell tumor of the tendon
sheath (GCT-TS), is a rare, typically non-malignant tumor that can be locally aggressive.
The current standard of care for TGCT is surgical resection. However, in patients with diffuse-type
TGCT, the tumor may wrap around bone, tendons, ligaments and other parts of the joint. In these cases,
the tumor may be difficult to remove and/or may not be amenable to improvement with surgery.4
Multiple surgeries for more severe cases can lead to significant joint damage, debilitating functional
impairments and reduced quality of life, and amputation may be considered.4,5
Recurrence rates for localized TGCT are estimated to be up to 15 percent following complete resection.
Diffuse TGCT recurrence rates are estimated to be about 20 percent to 50 percent following complete
resection.1,6 TGCT affects all age groups; the diffuse type on average occurs most often in people below
the age of 40, and the localized type typically occurs in people between 30 and 50 years old.6
About Pexidartinib
Pexidartinib is an oral small molecule that inhibits CSF-1R (colony stimulating factor-1 receptor),
which is a primary growth driver of abnormal cells in the synovium that cause TGCT. Pexidartinib also
inhibits KIT and FLT3-ITD. Pexidartinib was discovered by Plexxikon Inc., the small molecule
structure-guided R&D center of Daiichi Sankyo.
Pexidartinib is currently being studied in two studies as a potential treatment for patients with TGCT in
Japan, Taiwan and China. It is not approved for use in any country outside of the U.S.
About Daiichi Sankyo Cancer Enterprise
The mission of Daiichi Sankyo Cancer Enterprise is to leverage our world-class, innovative science and
push beyond traditional thinking to create meaningful treatments for patients with cancer. We are
dedicated to transforming science into value for patients, and this sense of obligation informs
3
everything we do. Anchored by our DXd antibody drug conjugate (ADC) technology, our powerful
research engines include biologics, medicinal chemistry, modality and other research laboratories in
Japan, and Plexxikon Inc., our small molecule structure-guided R&D center in Berkeley, CA. For more
information, please visit: www.DSCancerEnterprise.com.
About Daiichi Sankyo
Daiichi Sankyo Group is dedicated to the creation and supply of innovative pharmaceutical therapies to
improve standards of care and address diversified, unmet medical needs of people globally by
leveraging our world-class science and technology. With more than 100 years of scientific expertise and
a presence in more than 20 countries, Daiichi Sankyo and its 15,000 employees around the world draw
upon a rich legacy of innovation and a robust pipeline of promising new medicines to help people. In
addition to a strong portfolio of medicines for cardiovascular diseases, under the Group’s 2025 Vision
to become a “Global Pharma Innovator with Competitive Advantage in Oncology,” Daiichi Sankyo is
primarily focused on providing novel therapies in oncology, as well as other research areas centered
around rare diseases and immune disorders. For more information, please visit:
www.daiichisankyo.com.
Media Contacts:
Global/US:
Don Murphy
Daiichi Sankyo, Inc.
domurphy@dsi.com
+1 917 817 2649 (mobile)
Japan:
Masashi Kawase
Daiichi Sankyo Co., Ltd.
kawase.masashi.a2@daiichisankyo.co.jp
+81 3 6225 1126 (office)
Investor Relations Contact:
DaiichiSankyoIR@daiichisankyo.co.jp
1 de Saint Aubain, et al. WHO. 2013;100-103.
2 Rao AS, et al. J Bone Joint Surg AM. 1984;66(1):76-94.
3 Ravi V, et al. Curr Opin Oncol. 2011;23:361-366.
4 van der Heijden L, et al. J Surg Oncol. 2013;107(4):433-445.
5 van der Heijden L, et al. Bone Joint J. 2014;96-B:1111-1118.
6 Ehrenstein V, et al. J Rheumatol. 2017; 44(10):1476-1483.

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