- 63% response rate observed in 24 evaluable patients - 79% overall survival rate at 12 months; 9 months median progression-free survival - Conference call on Thursday, 22.

- 63% response rate observed in 24 evaluable patients
- 79% overall survival rate at 12 months; 9 months median
progression-free survival
- Conference call on Thursday, May 22, at 5:30 p.m. (Eastern Time)
UTRECHT, Netherlands, and CAMBRIDGE, Massachusetts, May 24, 2025 (GLOBE
NEWSWIRE) -- Merus NV (https://merus.nl/)(Nasdaq: MRUS) (Merus, the
Company, we or our), an oncology company that develops innovative
multispecific full-length antibodies and antibody-drug conjugates
(Biclonics(®), Triclonics(®) and ADClonics(®)), today announced preliminary
clinical data as of February 27, 2025 from the ongoing Phase II
Study with the bispecific antibody petosemtamab in combination with
Pembrolizumab. These data are presented by Dr. Carla ML van Herpen,
MD, Ph.D., Radboud University Medical Center, Nijmegen, The Netherlands, on
Monday, June 2, from 9:00 a.m. to 12:00 p.m. (Central Time) at the 2025 Annual Meeting
presented by the American Society of Clinical Oncology® (ASCO®).
?We believe that these preliminary data clearly
are better than monotherapy with pembrolizumab, the control arm of our
ongoing Phase III study, and underline the opportunity that petosemtamab in
In case of approval for a new standard of care for head and neck cancer
can be," said Dr. Bill Lundberg, President and Chief Executive Officer of
Merus. ?Furthermore, we believe that our execution with the rapid
The opening of the test centers is excellent. We look forward to
possibly in 2026 first preliminary results of one or both phase-
III studies to be published."
?Squamous cell carcinoma of the head and neck region is associated with poor
prognosis and a high mortality rate, and there is still
there is a need for new treatment options for patients," added Dr. van
Herpes simplex. ?In my clinic, when administering petosemtamab,
a significant tumor shrinkage was observed, and the efficacy results, which
Petosemtamab in combination with the current standard drug
Pembrolizumab is promising. I am excited about the
impressive ORR and the durability of these responses and what
These results, if confirmed on a larger scale, will be of interest to the future
our practice in head and neck cancer."
Petosemtamab (MCLA-158: EGFR x LGR5 Biclonics(®)): Solid tumors
Title of the presentation: Petosemtamab (MCLA-158) with pembrolizumab as first-line
(1L) treatment of PD-L1+ recurrent/metastatic (r/m) head and neck squamous cells
carcinoma (HNSCC): Phase 2 trial (petosemtamab (MCLA-158) with pembrolizumab as
First-line therapy (1L) of PD-L1-positive recurrent/metastatic
(r/m) Head and neck squamous cell carcinoma (HNSCC): Phase II study)
The observations in the presentation include, as of 27 February
2025:
* 45 patients were treated
* The efficacy population consisted of 43 patients who were
had been treated (with one or more doses) by the data cut-off date and
either had >= 1 post-baseline tumor assessment or who were
Disease progression or death prematurely eliminated
* Median follow-up time of 14.3 months for the 45 patients
* In 43 evaluable patients:
* Confirmed overall response rate: 63% (27/43, 95% CI: 49-75) according to the
 Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. after
Investigator’s assessment, including:
* Response in 4 of 8 patients with HPV-related cancer
* Overall response across PD-L1 stages (CPS 1-19: 47% [8/17];
CPS > 20: 73% [19/26])
* Median progression-free survival was 9 months (95% CI:
5.2-12.9)
* The median duration of response and median overall survival (overall
Survival, OS) were not achieved
* Overall survival rate of 79% at 12 months (30/43 censored)
* As of the cut-off date, 14 patients, all responders, remained in
 Treatment
* In 45 patients, the combination was well tolerated and no
significant toxicities overlapping with pembrolizumab were observed
* Treatment-related adverse events were reported in 45 patients
 (Treatment-Emergent Adverse Events, TEAEs).
* Grade >=3 TEAEs occurred in 27 (60%) patients, including 20 (44%)
Patients who experienced treatment-related TEAEs
* Infusion-related reactions (composite term) were reported in 38%
(all grades) and 7% (grade 3) of patients, no grade 4 or
5, occurred mainly during the first infusion and then subsided
 away
Abstract No.: 6024
Poster board: 432
Session title: Head and Neck Cancer
Date and time of meeting: June 2, 2025, 9:00-12:00 CT
Once the complete presentations at the ASCO(®) Annual Meeting 2025
are available, they will be published simultaneously on the website
(https://merus.nl/technology/publications/) published by Merus.
An analysis of confirmed reactions observed with the administration of
Petosemtamab in first-line combination therapy (as of the data cut-off date of 27
February 2025) and in the second-line plus monotherapy Phase II cohort (to
data cut-off date of July 5, 2024) showed that two-thirds
these responses to petosemtamab in HPV-associated p16+ oropharyngeal carcinoma
occurred in non-smokers.
Information about the company's conference call and webcast
Merus will host a conference call on Thursday, May 22, 2025, at 5:30 p.m. ET
and hold a webcast for investors. Following the conference call
will be recorded for a limited period in the Investors and
Media (https://ir.merus.nl/event-calendar) on our website
stand.
Date and time: May 22, 2025 at 5:30 PM Eastern Time
Webcast link: Available on our website (https://ir.merus.nl/event-calendar)
Dial-in number(s): Toll-free: (800) 715-9871 / International: (646) 307-1963
Conference ID: 7517301 or Merus NV Conference Call
About Merus NV
Merus (https://merus.nl/about/)Multiclonics
(https://merus.nl/technology/multiclonics-platform/)(®)
(https://merus.nl/technology/multiclonics-platform/)(®) are
industry standard procedures and have been used in preclinical and
clinical studies have shown that they have several of the same properties as
conventional human monoclonal antibodies, such as a long
Half-life and low immunogenicity. For further information, see
on the Merus website (https://merus.nl/), LinkedIn
(https://www.linkedin.com/company/merus) and Bluesky
(https://bsky.app/profile/merusnv.bsky.social).
Forward-looking statements
This press release contains forward-looking statements within the meaning of the Private
Securities Litigation Reform Act of 1995. All in this
Statements contained in this press release that are not based on historical facts
should be considered forward-looking statements,
including, but not limited to, statements regarding clinical development
our clinical candidates such as petosemtamab, to future results
clinical trials or preliminary data, on clinical efficacy and
Safety profile and development plans in the ongoing studies conducted in
described in future posters or presentations; our belief
that petosemtamab in combination with pembrolizumab in this preliminary
data set in almost all metrics are significantly better than the
Standard therapy; our belief that these data demonstrate the enormous potential of
Underline petosemtamab as a new standard therapy for head and neck cancer;
our statements on our further course of action, including the rapid
Opening of the trial centers. These forward-looking statements are based on the
current expectations of management. They are neither promises nor
Guarantees and are subject to known and unknown risks, uncertainties and
other important factors that may cause our actual
results, performance or achievements significantly differ from future results,
developments or successes that may differ from those indicated by the forward-looking
statements expressed or implied. These include, but are not limited to: our need
of additional financial resources that may not be available, so that we
restrict our business or rights to our technologies or
antibody candidates; potential delays in receiving the
legal approval relating to the commercialization of our product candidates
and the generation of sales/profits; the lengthy and
expensive clinical drug development processes with uncertain outcomes;
the unpredictability of our preclinical phase
Efforts to develop marketable drugs; possible delays in
the admission of patients, which ensures the receipt of the required statutory
approvals; our dependence on third parties for
Conduct of our clinical trials and the unsatisfactory
performance of these third parties; the impact of global economic volatility,
including global instability, including the ongoing
conflicts in Europe and the Middle East; that we, as part of our
Cooperation may not be suitable Biclonics® or bispecific
identify antibody candidates or that the performance in the context of
our cooperation may not be satisfactory; our dependence on
Third parties regarding the production of our product candidates, our
Development and sales efforts may be delayed, prevented or
impaired; protection of our proprietary technology; our patents are
may be found invalid or unenforceable, by competitors
circumvented, and our patent applications may not be filed for the
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registered or unregistered trademarks or trade names
may be challenged, infringed, circumvented or declared generic or
deemed to infringe other trademarks.
These and other important factors listed under the heading "Risk Factors"
in our Quarterly Report on Form 10-Q for the period ended March 31
2025 filed with the Securities and Exchange Commission (SEC) on May 7, 2025
and in our other reports filed with the SEC
described could cause the actual results
materially from the forward-looking statements made in this press release
statements. These forward-looking statements reflect the assessments
of the management at the time of publication of this press release
We are entitled, but not obliged, to
forward-looking statements at any given time may
update, and disclaim any obligation to do so, even if our
Change views as a result of future events, unless this is
required by applicable law. These forward-looking statements should
not be construed as our views at any time subsequent to the date of this
Press release can be understood.
Multiclonics(®), Biclonics(®), Triclonics(®) and ADClonics(®) are registered
Brands of Merus NV
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