-   60% response rate observed among 10 evaluable patients
 -   Favorable safety profile in 26 patients enrolled as of the abstract cutoff
           date, with no significant overlapping toxicities observed
 -   Conference call on Tuesday, May 28 at 8:00 a.m. ET to discuss full ASCO(®)
                                    data set

UTRECHT, The Netherlands and CAMBRIDGE, Mass., May 23, 2024 (GLOBE NEWSWIRE) --
Merus N.V. (https://merus.nl/) (Nasdaq: MRUS) (Merus, the Company, we, or our),
a clinical-stage oncology company developing innovative, full-length
multispecific antibodies (Biclonics(®) and Triclonics(®)), today announced the
publication of an abstract regarding petosemtamab in combination with
pembrolizumab on the 2024 American Society of Clinical Oncology(®) (ASCO(®))
Annual Meeting website (https://meetings.asco.org/abstracts-
presentations/search?query=*&q=*&sortBy=AbstractBrowse&filters=%7B%22presentatio
nType%22:%5B%7B%22key%22:%22Abstract%22%7D%5D,%22meetingYear%22:%5B%7B%22key%22:
%222024%22%7D%5D,%22meetingTypeName%22:%5B%7B%22key%22:%22ASCO%20Annual%20Meetin
g%22%7D%5D%7D&size=50). The abstract presents interim clinical data from a
cohort of 26 patients enrolled as of the abstract cutoff date, evaluating the
combination in first line (1L) recurrent/metastatic (r/m) head and neck squamous
cell carcinoma (HNSCC) for presentation at the 2024 ASCO(®) Annual Meeting
taking place in Chicago, May 31-June 4, 2024.
The full dataset for these patients will be discussed on a conference call on
Tuesday, May 28 at 8:00 a.m. ET.
"We believe petosemtamab continues to demonstrate potential best in class safety
and efficacy in head and neck cancer. We are encouraged with the well tolerated
safety profile of the combination of petosemtamab and pembrolizumab,
particularly with a low rate of Grade 3 or greater adverse events, and a low
rate of infusion-related reactions observed," said Bill Lundberg, M.D.,
President, Chief Executive Officer of Merus. "These data in the abstract provide
encouraging efficacy albeit from an early cutoff date, with less mature data.
And we look forward to our conference call, Tuesday May 28, to discuss the more
mature clinical update from a later cutoff date where the response rate further
improved."
Petosemtamab (MCLA-158: EGFR x LGR5 Biclonics(®)): Solid Tumors
Rapid oral presentation title: Petosemtamab (MCLA-158) with pembrolizumab as
first-line (1L) treatment of recurrent/metastatic (r/m) head and neck squamous
cell carcinoma (HNSCC): Phase 2 study.
Observations in the abstract include:

  * As of a November 6, 2023 data cutoff date, 26 patients (pts) were treated;
    with 24 continuing therapy
      * 10 pts were evaluable for response (>=2 cycles and >=1 post-baseline scan,
        or early progressive disease (PD)) and 6 responses were observed. This
        included 1 confirmed complete response, 2 confirmed partial responses,
        and 3 unconfirmed partial responses (2 confirmed as of the abstract
        submission and the 3(rd) also subsequently confirmed) by Response
        Evaluation Criteria in Solid Tumors v1.1
      * The combination was well tolerated and no significant overlapping
        toxicities were observed. Treatment-emergent adverse events were
        reported in all patients, most were Grade 1 or 2 in severity. Infusion
        related reactions (composite term) were reported in 26.9% (all Grades)
        of which 3.8% were Grade 3, and all occurred during first infusion and
        resolved.

Presentation Details:
Abstract #: 6014
Session Title: Head and Neck Cancer
Session Date and Time: June 3, 2024, 8:00-9:30 a.m. CT
As full presentations become available at the 2024 ASCO(®) Annual Meeting, they
will contemporaneously be available on the Merus website
(https://merus.nl/technology/publications/).
Company Conference Call and Webcast Information
Merus will hold a conference call and webcast for investors on Tuesday, May
28, 2024 at 8:00 a.m. ET. A replay will be available after the completion of the
call in the Investors and Media (https://ir.merus.nl/event-calendar) section of
our website for a limited time.
Date & Time: May 28, 2024 at 8:00 a.m. ET
Webcast link: Available on our website (https://ir.merus.nl/event-calendar)
Dial-in: Toll Free: 1 (800) 715-9871/ International: 1 (646) 307-1963
Conference ID: 4160163
About Merus N.V.?
Merus (https://merus.nl/about/) is a clinical-stage oncology company developing
innovative full-length human bispecific and trispecific antibody therapeutics,
referred to as Multiclonics(®) (https://merus.nl/technology/multiclonics-
platform/). Multiclonics(®) are manufactured using industry standard processes
and have been observed in preclinical and clinical studies to have several of
the same features of conventional human monoclonal antibodies, such as long
half-life and low immunogenicity. For additional information, please visit
Merus' website, http://www.merus.nl (http://www.merus.nl/)
and https://twitter.com/MerusNV.?
Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the
Private Securities Litigation Reform Act of 1995. All statements contained in
this press release that do not relate to matters of historical fact should be
considered forward-looking statements, including without limitation statements
regarding the clinical development of our clinical candidates, including
petosemtamab, future clinical trial results or interim data, clinical activity
and safety profile, and development plans in the on-going trials and described
in forthcoming posters or presentations; our belief that petosemtamab continues
to demonstrate potential best in class safety and efficacy in head and neck
cancer; the observations of response rate and safety profile of the combination
of petosemtamab and pembrolizumab, and any impact on future patients treated
with this combination. These forward-looking statements are based on
management's current expectations. These forward-looking statements are based on
management's current expectations. These statements are neither promises nor
guarantees, but involve known and unknown risks, uncertainties and other
important factors that may cause our actual results, performance or achievements
to be materially different from any future results, performance or achievements
expressed or implied by the forward-looking statements, including, but not
limited to, the following: our need for additional funding, which may not be
available and which may require us to restrict our operations or require us to
relinquish rights to our technologies or Biclonics(®), Triclonics(®) and
multispecific antibody candidates; potential delays in regulatory approval,
which would impact our ability to commercialize our product candidates and
affect our ability to generate revenue; the lengthy and expensive process of
clinical drug development, which has an uncertain outcome; the unpredictable
nature of our early stage development efforts for marketable drugs; potential
delays in enrollment of patients, which could affect the receipt of necessary
regulatory approvals; our reliance on third parties to conduct our clinical
trials and the potential for those third parties to not perform satisfactorily;
impacts of the market volatility; we may not identify suitable Biclonics(®) or
bispecific antibody candidates under our collaborations or our collaborators may
fail to perform adequately under our collaborations; our reliance on third
parties to manufacture our product candidates, which may delay, prevent or
impair our development and commercialization efforts; protection of our
proprietary technology; our patents may be found invalid, unenforceable,
circumvented by competitors and our patent applications may be found not to
comply with the rules and regulations of patentability; we may fail to prevail
in potential lawsuits for infringement of third-party intellectual property; and
our registered or unregistered trademarks or trade names may be challenged,
infringed, circumvented or declared generic or determined to be infringing on
other marks.
These and other important factors discussed under the caption "Risk Factors" in
our Annual Report on Form 10-Q for the quarter ended March 31, 2024 filed with
the Securities and Exchange Commission, or SEC, on May 8, 2024, and our other
reports filed with the SEC, could cause actual results to differ materially from
those indicated by the forward-looking statements made in this press release.
Any such forward-looking statements represent management's estimates as of the
date of this press release. While we may elect to update such forward-looking
statements at some point in the future, we disclaim any obligation to do so,
even if subsequent events cause our views to change, except as required under
applicable law. These forward-looking statements should not be relied upon as
representing our views as of any date subsequent to the date of this press
release.
Multiclonics(®), Biclonics(®) and Triclonics(®) are registered trademarks of
Merus N.V.
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