Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) announced today that presentations on a series of abstracts highlighting updates on its in-house discovered eribulin mesylate (product name: Halaven®, halichondrin class microtubule dynamics inhibitor, “eribulin”), MORAb-202, an antibody drug conjugate (ADC), and H3B-6545 (selective estrogen alpha receptor covalent antagonist), discovered by Eisai’s U.S. research subsidiary H3 Biomedicine Inc., will be given at the 44th San Antonio Breast Cancer Symposium (SABCS2021) to be held, partly virtual, from December 7 to 10, 2021, in San Antonio, Texas in the United States.


At this symposium, regarding eribulin, the result of non-clinical studies on its effects to subsequent chemotherapy through the induction of mesenchymal-epithelial transition (Abstract No: P3-06-01) is scheduled to be presented.


MORAb-202 is Eisai’s first ADC and combines Eisai’s in-house developed anti-folate receptor alpha (FRa) antibody, to Eisai’s anticancer agent eribulin, using an enzyme cleavable linker. At this symposium, regarding MORAb-202, the experimental results of antitumor efficacy in Patient-Derived Xenograft models of triple-negative breast cancer (Abstract No: P5-08-02) is scheduled to be presented. In June 2021, Eisai and Bristol-Myers Squibb Company (Headquarters: the United States) entered into an exclusive global strategic collaboration agreement for the co-development and co-commercialization of MORAb-202.


In addition, regarding H3B-6545, the results of Phase II clinical study evaluating monotherapy (Abstract No: P1-17-10) and Phase 1b study evaluating the combination therapy with palbociclib (Abstract No: P1-17-03) in estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer will be presented.


Eisai positions oncology as a key therapeutic area, and is aiming to discover revolutionary new medicines with the potential to cure cancer. Eisai is aspiring to making further contribution to addressing the diverse needs of, and increasing the benefits provided to, patients with cancer, their families, and healthcare providers through creating innovative new drugs based on cutting-edge cancer research.


This release discusses investigational compounds and investigational uses for FDA-approved products. It is not intended to convey conclusions about efficacy and safety. There is no guarantee that any investigational compounds or investigational uses of FDA-approved products will successfully complete clinical development or gain FDA approval.


Major poster presentations at SABCS2021:

Product / Compound
Abstract No.
Title / Scheduled Date and Time (local time: Central Standard Time)
Eribulin alters the chromatin landscape to induce MET, attenuating metastatic progression and sensitizing breast tumors to subsequent chemotherapy
December 9 (Thu), 7:00AM - 8:30AM
MORAb-202, an Antibody-drug-conjugate (ADC) targeting Folate Receptor Alpha (FRα), exhibits durable anti-tumor efficacy in PDx models of TNBC
December 10 (Fri), 7:00AM - 8:30AM
H3B-6545, a novel selective estrogen receptor covalent antagonist (SERCA), in estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer – A Phase II study
December 8 (Wed), 7:00AM - 8:30AM


H3B-6545 in combination with palbociclib in women with metastatic estrogen receptor–positive (ER+), human epidermal growth factor receptor 2 (HER2)-negative breast cancer, Phase 1b study

December 8 (Wed), 7:00AM - 8:30AM


Media Inquiries:

Public Relations Department,

Eisai Co., Ltd.




[Notes to editors]

1. Eisai’s Focus on Cancer

Eisai focuses on the development of anticancer drugs, targeting the tumor microenvironment (with experience and knowledge from existing in-house discovered compounds) and the driver gene mutation and aberrant splicing (leveraging RNA Splicing Platform) as areas (Ricchi) where real patient needs are still unmet, and where Eisai can aim to become a frontrunner in oncology. Eisai aspires to discover innovative new drugs with new targets and mechanisms of action from these Ricchi, with the aim of contributing to the cure of cancers.