Mersana Therapeutics Announces Target and Presents New Preclinical Data for XMT-2056, First Immunosynthen STING-Agonist ADC, at AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics
October 07 2021 - 4:05PM
Mersana Therapeutics, Inc. (NASDAQ:MRSN), a clinical-stage
biopharmaceutical company focused on discovering and developing a
pipeline of antibody-drug conjugates (ADCs) targeting cancers in
areas of high unmet medical need, today announced that XMT-2056,
its first Immunosynthen STING-agonist ADC candidate, targets a
novel epitope of human epidermal growth factor receptor 2 (HER2)
and presented new preclinical data during a plenary session at the
AACR-NCI-EORTC Virtual International Conference on Molecular
Targets and Cancer Therapeutics (Triple Meeting).
“Previously, across multiple targets and models,
we demonstrated that our Immunosynthen ADCs can stimulate the
innate immune system in a targeted manner in both tumor cells and
tumor-resident myeloid cells – a “one-two punch” resulting in
robust efficacy. New head-to-head preclinical data comparing
XMT-2056 to TLR7/8-agonist ADC and systemically-administered STING
agonist benchmarks further supports the potential advantages of
XMT-2056 to offer greater efficacy and a wider therapeutic index,”
said Timothy B. Lowinger, PhD, Chief Science and Technology Officer
of Mersana Therapeutics. “In addition, new data with XMT-2056 in
combination with trastuzumab supports our rationale for selecting
an antibody that recognizes a novel epitope of HER2, providing
broad combination potential with approved and investigational HER2
therapies.”
“STING is a fundamental mechanism yet approaches
to date have been unsuccessful at stimulating the innate immune
system in a targeted manner. Our Immunosynthen platform not only
has the potential to address this limitation but also is designed
to allow us to extend our ADC development efforts beyond cytotoxic
payloads, which we believe represents a significant advancement in
the ADC field,” said Anna Protopapas, President and Chief Executive
Officer of Mersana Therapeutics. “We are particularly excited about
the potential of XMT-2056 to offer a novel approach to the
treatment of HER2-expressing tumors both as a single agent and in
combination.”
Previously reported preclinical data suggest
that XMT-2056 offers a highly differentiated approach, enabling
tumor-targeted delivery of a STING agonist with improved
efficacy and tolerability over a systemically-administered
STING agonist benchmark. In vitro and in
vivo studies demonstrate that STING-agonist ADCs activate
the STING pathway in both tumor-resident immune cells and
tumor cells, offering the potential for an increased therapeutic
index and an advantage over other innate immune activating
pathways.
The Company has evaluated Immunosynthen ADCs
across a wide range of antibodies, targets, tumor models and mouse
strains and observed broad efficacy and consistent results
demonstrating target-dependent anti-tumor effects and has selected
HER2 as the first target for clinical evaluation with XMT-2056. The
Company developed a differentiated anti-HER2 antibody that binds a
novel epitope distinct from that of trastuzumab and pertuzumab,
providing the opportunity for combinations with these
well-established anti-HER2 therapies.
New preclinical data presented today at the
Triple Meeting include:
- XMT-2056 demonstrated increased
efficacy in both high and low HER2 SCID mouse models in comparison
to benchmark agents such as a trastuzumab-TLR7/8 agonist ADC as
well as a small molecule systemically-administered STING
agonist.
- XMT-2056 showed excellent in vivo
efficacy as a single agent in a SKOV3 HER2 high model and this
efficacy is further enhanced by combining XMT-2056 with a 3 mg/kg
dose of trastuzumab.
- XMT-2056 was generally
well-tolerated in NHP studies with no clinical signs and no adverse
findings in clinical pathology or histopathology after single and
repeat IV doses of 9 mg/kg, at exposures far exceeding those
necessary for efficacy in mouse models, indicating the potential
for a wide therapeutic index.
About Mersana
TherapeuticsMersana Therapeutics is a clinical-stage
biopharmaceutical company using its differentiated and proprietary
ADC platforms to rapidly develop novel ADCs with optimal efficacy,
safety and tolerability to meaningfully improve the lives of people
fighting cancer. Mersana’s lead product candidate, upifitamab
rilsodotin (UpRi), is a Dolaflexin ADC targeting NaPi2b and is
being studied in UPLIFT, a single-arm registration strategy in
patients with platinum-resistant ovarian cancer, as well as in
UPGRADE, a Phase 1 umbrella study in combination with other ovarian
cancer therapies. UpRi is also being studied in the expansion
portion of a Phase 1 proof-of-concept clinical study. XMT-1592,
Mersana’s second ADC product candidate targeting NaPi2b-expressing
tumors, was created using Mersana’s customizable and homogeneous
Dolasynthen platform and is in the dose escalation portion of a
Phase 1 proof-of-concept clinical study. The Company’s early-stage
programs include XMT-1660, a Dolasynthen ADC targeting B7-H4, as
well as XMT-2056, a STING-agonist ADC targeting a novel epitope of
HER2, developed using the Company’s Immunosynthen platform. In
addition, multiple partners are using Mersana’s Dolaflexin platform
to advance their ADC pipelines. The Company routinely posts
information that may be useful to investors on the “Investors and
Media” section of our website at www.mersana.com.
Forward-Looking Statements
This press release contains “forward-looking”
statements within the meaning of federal securities laws. These
forward-looking statements are not statements of historical facts
and are based on management’s beliefs and assumptions and on
information currently available to management. Forward-looking
statements include information concerning the Company’s business
strategy and the design, progression and timing of its clinical
trials, the ability of the single-arm UPLIFT cohort to enable
registration, the potential benefits of our product candidates, and
expectations regarding future clinical trial results based on data
achieved to date. Forward-looking statements generally can be
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“promises to be,” “seeks,” “should,” “target,” “will,” “would” or
similar expressions and the negatives of those terms.
Forward-looking statements represent management’s beliefs and
assumptions only as of the date of this press release. The
Company’s operations involve risks and uncertainties, many of which
are outside its control, and any one of which, or combination of
which, could materially affect its results of operations and
whether the forward-looking statements ultimately prove to be
correct. Factors that may materially affect the Company’s results
of operations and whether these forward-looking statements prove to
be correct include, among other things, that preclinical testing or
early clinical results may not be predictive of the results or
success of ongoing or later preclinical or clinical studies, that
the identification, development and testing of the Company’s
product candidates and new platforms will take longer and/or cost
more than planned, and that our clinical studies may not be
initiated or completed on schedule, if at all, as well as those
listed in the Company’s Quarterly Report on Form 10-Q filed on
August 6, 2021, with the Securities and Exchange Commission
(“SEC”), and subsequent SEC filings. In addition, while we expect
that the COVID-19 pandemic might adversely affect the Company’s
preclinical and clinical development efforts, business operations
and financial results, the extent of the impact on the Company’s
operations and the value of and market for the Company’s common
stock will depend on future developments that are highly uncertain
and cannot be predicted with confidence at this time, such as the
ultimate duration of the pandemic, travel restrictions,
quarantines, physical distancing and business closure requirements
in the U.S. and in other countries, and the effectiveness of
actions taken globally to contain and treat the disease. Except as
required by law, the Company assumes no obligation to update these
forward-looking statements publicly, or to update the reasons
actual results could differ materially from those anticipated in
the forward-looking statements, even if new information becomes
available in the future.
Contact:
Investor & Media ContactSarah
Carmody617-844-8577scarmody@mersana.com
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