H3 Biomedicine to Present Data from Two Ongoing Precision Medicine Clinical Programs at 2019 ASCO Annual Meeting

—Phase 1 dose escalation of H3B-6545, a potential first-in-class
Selective ERα Covalent Antagonist (SERCA), in women with ER-positive,
HER2-negative breast cancer—

—Phase 1 study of H3B-6527, an investigational fibroblast growth
factor receptor 4 (FGFR4) inhibitor, in hepatocellular carcinoma or
intrahepatic cholangiocarcinoma patients—

CAMBRIDGE, Mass.–(BUSINESS WIRE)–H3 Biomedicine Inc., a U.S.-based precision medicine research &
development subsidiary of Eisai Co., Ltd., today announced it will
present four posters during the 2019 American Society of Clinical
Oncology (ASCO) Annual Meeting, which will be held May 31 – June 4, 2019
in Chicago.

The presentations will include interim data from two of H3’s ongoing
clinical development programs. These include a Phase 1 study of
H3B-6545, a potential first-in-class, orally available Selective ERα
Covalent Antagonist (SERCA), in women with ER-positive, HER2-negative
breast cancer; and a Phase 1 study of H3B-6527, an investigational
selective, orally available, inhibitor of fibroblast growth factor
receptor 4 (FGFR4), in patients with hepatocellular carcinoma (HCC) or
intrahepatic cholangiocarcinoma (ICC). H3 will also present posters
demonstrating the utilization of biomarker and companion diagnostic
strategies for both programs.

The clinical data abstracts published online today for the H3B-6545 and
H3B-6527 Phase 1 studies reflect data as of December 18, 2018 and
January 6, 2019, respectively. Updated results from both studies will be
presented at ASCO.

The schedule for H3’s ASCO presentations is as follows:

H3B-6545 Presentations

Abstract Number: 1059
Title: Phase 1 dose escalation
of H3B-6545, a first-in class highly Selective ERα Covalent Antagonist
(SERCA), in women with ER-positive, HER2-negative breast cancer
Session:
Breast Cancer – Metastatic
Date and Time: June 2, 2019;
8:00 – 11:00 am CDT
Presenter: Erika P. Hamilton,
M.D., Director, Breast and Gynecologic Cancer Research Program, Sarah
Cannon Research Institute

Abstract Number: 1052
Title: Molecular
characterization and monitoring of patient circulating tumor (ctDNA) in
phase I study of H3B-6545 in ER+ metastatic breast cancer
Session: Breast
Cancer—Metastatic
Date and Time: June 2, 2019; 8:00 AM-11:00
AM CDT
Presenter: Victoria Rimkunas, Ph.D., Associate
Director, Biomarkers and Companion Diagnostics, H3 Biomedicine

H3B-6527 Presentations

Abstract Number: 4095
Title: A phase 1 study of
H3B-6527 in hepatocellular carcinoma (HCC) or intrahepatic
cholangiocarcinoma (ICC) patients
Session: Gastrointestinal
(noncolorectal) cancer
Date and Time: June 3, 2019; 8:00 –
11:00 AM CDT
Presenter: Teresa Macarulla, M.D., Ph.D.,
Gastrointestinal Tumor Unit, Institute of Oncology Barcelona-Madrid

Abstract Number: 4121
Title: H3B-6527 clinical
biomarker assay development and characterization of HCC patient samples
Session: Gastrointestinal
(non-colorectal) cancer
Date and Time: June 3, 2019; 8:00 –
11:00 AM CDT
Presenter: Pavan Kumar, Ph.D., Head of
Biomarkers and Companion Diagnostics, H3 Biomedicine

About H3B-6545

H3B-6545 irreversibly inactivates ERα by covalently binding a cysteine
residue in ERα that is not present in other nuclear hormone receptors.
It is believed that binding of SERCA to ERα leads to divergent
biological activity that is differentiated from classical Selective
Estrogen Receptor Modulators (SERMs) and Selective Estrogen Receptor
Degraders (SERDs), two classes of standard-of-care endocrine therapies.

The Phase 1 H3B-6545 study is evaluating the safety, pharmacokinetics
and pharmacodynamics of H3B-6545 in women with ER-positive,
HER2-negative breast cancer to identify the recommended Phase 2 dose.
Patients are treated with H3B-6545 administered once daily orally over a
28-day cycle after progression on at least one hormonal therapy and at
least one additional therapy/regimen. Dose escalation uses a 3+3 design
with the option to backfill previously cleared doses and allows for
intra-patient dose escalation.

About H3B-6527

FGF19 overexpression is hypothesized to hyperactivate FGFR4 and its
downstream signaling pathway leading to enhanced tumor growth in
patients with HCC or ICC. Targeting FGFR4 may have therapeutic benefit
in HCC/ICC with altered FGF19 signaling. A phase 1 study was initiated
to assess H3B-6527, an investigational covalent FGFR4 inhibitor.

The Phase 1 H3B-6527 study is assessing the safety, pharmacokinectics
and pharmacodynamics of H3B-6527 in adult patients with advanced HCC or
ICC, well compensated liver function, and who progressed after at least
one prior therapy. Patients are administered H3B-6527 once daily orally
on a 21-day cycle following a 3+3 design. Patients in the dose
escalation phase are treated regardless of FGF19 status.

About H3 Biomedicine

H3 Biomedicine, Inc. is a Cambridge, Massachusetts-based
biopharmaceutical company specializing in the discovery and development
of novel precision oncology treatments using its integrated data
science, human biology and precision chemistry discovery engine with the
goal of improving the lives of patients. The company was established in
December 2010 as a subsidiary of Eisai’s U.S. pharmaceutical operation,
Eisai Inc. H3 Biomedicine focuses on sustained long-term delivery of its
pipeline, collaborating with Eisai Co., Ltd., who provides essential
research funding and access to the capabilities and resources of a
global pharmaceutical company. For more information, please visit www.h3biomedicine.com.

Contacts

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