Merus Announces Publication of Abstract on MCLA-129 at the 34th EORTC/NCI/AACR (ENA) Symposium on Molecular Targets and Cancer Therapeutics


Merus AG

– MCLA-129 was well tolerated with preliminary evidence of anti-tumor activity during the dose escalation phase

– Recommended initial phase two dose set at 1500 mg with ongoing dose extension

– Poster presentation with additional data at ENA available October 26, 9am CET/3am ET, and presented October 28, 2022, 10am-3pm CET

– Call for investors to discuss an update to the MCLA-129 program on October 26 at 1:30 p.m. CET / 7:30 a.m. ET

UTRECHT, Netherlands and CAMBRIDGE, Mass., Oct. 12, 2022 (GLOBE NEWSWIRE) — Merus NV (Nasdaq: MRUS) (“Merus”, “the Company”, “we” or “our”), a late-stage oncology developing innovative full-length multispecific antibodies (Biclonics® and Triclonics®), today announced the publication of the abstract highlighting interim data from the ongoing Phase 1/2 trial of the bispecific antibody MCLA-129 on the 34e Website of the EORTC/NCI/AACR Symposium on Molecular Targets and Cancer Therapeutics (ENA Symposium). MCLA-129 is a Biclonics® fully human IgG1 bispecific antibody that binds to EGFR and c-MET and is being studied in patients with advanced non-small cell lung cancer (NSCLC) and other solid tumors. This phase 1/2 study has completed the dose escalation phase and is continuing into the dose expansion phase.

The poster will be presented at 34e ENA Symposium in Barcelona, ​​Spain on Friday, October 28, 2022, from 10:00 a.m. to 3:00 p.m. CET, and will be available online on Wednesday, October 26, 2022. The poster presentation will include additional interim clinical data from this dose escalation cohort.

“We are encouraged by the promising initial clinical data for MCLA-129 presented in the abstract and look forward to providing additional clinical data from the dose escalation cohort in the poster presentation at the ENA symposium,” said Dr. Andrew Joe, Medical Director. Officer at Merus. “We also intend to share an update on the MCLA-129 program on our next conference call.”

The interim data reported in the abstract are from the Phase 1/2 trial of MCLA-129 in patients with advanced NSCLC and other solid tumors.

The information and observations contained in the summary include:

  • As of the May 8, 2022 cut-off date, 20 patients have been treated with MCLA-129 at doses of 100, 300, 600, 1000 and 1500 mg every other week

  • The median age of the patients was 65 years (range 43-79)

  • Enrolled tumor types included:

    • 14 patients with EGFR (mt) mutant NSCLC (4 L858R, 8 Del19, 1 exon 20 insertion, 1 other)

    • 2 patients with c-MET exon 14 mt NSCLC

    • 1 patient with gastric adenocarcinoma amplified by c-MET

    • 1 patient with esophageal squamous cell cancer

    • 2 patients with squamous cell carcinoma of the head and neck

  • 13 patients were evaluable for response with preliminary signs of anti-tumor activity observed:

  • The median duration of treatment was 8 weeks (range 3.4 to 29.3) with 11 patients still on treatment at the cut-off date

  • Security:

    • No dose limiting toxicities were observed and the maximum tolerated dose was not reached

    • The most commonly reported adverse event (AE) was infusion-related reaction (IRR)

      • 18 of 20 (90%) patients reported IRR after the first dose, all but one were mild or moderate (grade 1-2)

      • All but one of the infusions were performed on the same day

    • No discontinuation of treatment due to an AE

    • No interstitial lung disease was observed

  • The recommended starting Phase 2 dose for expansion is 1500 mg every two weeks. Expansion cohorts enroll.

    • A dose-dependent depletion of soluble EGFR and c-MET was observed

    • At doses ranging from 600 to 1,500 mg every other week, MCLA-129 demonstrated linear pharmacokinetics

    • Mean serum concentrations at 1500 mg every other week are modeled to be above those required for >95% target engagement of cell-bound EGFR and c-MET throughout the dosing period

Presentation details:

Title: MCLA-129, a human bispecific anti-EGFR and anti-c-MET antibody, in patients with advanced NSCLC and other solid tumors: an ongoing phase 1/2 study
First author: Teacher. Sai-Hong Ignatius Ou, Department of Medicine, Division of Hematology-Oncology, University of California Irvine School of Medicine, USA
Session: New therapies in immuno-oncology
Date: Friday, October 28, 2022
Time: 10:00-15:00 CET
Summary #: 341
Attach #: PB121

The poster will be available at the start of the conference on October 26, 2022 and on demand throughout the conference on the conference website. The poster will also be available on the Merus website at the same time.

Company Conference Call and Webcast Information

Merus will host an investor conference call and webcast on Wednesday, October 26, 2022 at 1:30 p.m. CET/7:30 a.m. ET to discuss initial clinical data for MCLA-129 and provide a program update. A replay will be available after the call ends in the Investors and Media section of our website for a limited time.

Date: October 26, 2022
Webcast link: available on our site
Compose: Toll free: 1 (800) 715-9871 / International: 1 (646) 307-1963
Conference ID: 1694377

About MCLA-129
MCLA-129 is an antibody-dependent cellular cytotoxicity Biclonics® designed to inhibit EGFR and c-MET signaling pathways in solid tumors. Preclinical data has shown that MCLA-129 can effectively treat TKI-resistant non-small cell lung cancer (NSCLC) in cancer xenograft models. MCLA-129 is designed to have two complementary mechanisms of action: blocking growth and survival pathways to arrest tumor expansion and recruiting and enhancing immune effector cells to eliminate the tumor.

About Merus AG
Merus is a clinical-stage oncology company developing innovative full-length human bispecific and trispecific therapeutic antibodies called Multiclonics®. Multiclonics® are manufactured using industry standard processes and have been observed in preclinical and clinical studies to exhibit many of the same characteristics as conventional human monoclonal antibodies, such as a long half-life and low immunogenicity. For more information, please visit Merus website, and

Forward-looking statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements in this press release that do not relate to historical facts should be considered forward-looking statements, including, without limitation, statements regarding the mechanisms of action of MCLA-129; the impact of observations regarding any interim clinical data, including on future results or development plans; any planned clinical or program updates; and the potential of MCLA-129 Biclonics® in preclinical or clinical development to treat cancer.

These forward-looking statements are based on management’s current expectations. These statements are not promises or 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 future results, performance or achievements. expressed or implied by the forward-looking statements. 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 relinquish rights to our technologies or Biclonics®, Triclonics ® and candidate multispecific antibodies; potential delays in regulatory approval, which would impact our ability to commercialize our product candidates and affect our ability to generate revenues; the long and costly process of clinical drug development, the outcome of which is uncertain; the unpredictable nature of our efforts to develop early-stage marketable drugs; potential delays in patient enrollment, which could affect the receipt of necessary regulatory approvals; our reliance on third parties to conduct our clinical trials and the possibility that such third parties may not perform satisfactorily; impacts of the COVID-19 pandemic; we may not identify suitable Biclonics® or bispecific antibody candidates in our collaborations or our collaborators may not perform well in 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 patentability rules and regulations; we may not prevail in any lawsuits for infringement of third-party intellectual property; and our registered or unregistered trademarks or trade names may be challenged, infringed, circumvented, or held to be generic or determined to infringe other trademarks.

These and other important factors discussed under “Risk Factors” in our Quarterly Report on Form 10-Q for the period ended June 30, 2022 filed with the Securities and Exchange Commission, or SEC, on August 8, 2022 , 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. These forward-looking statements represent management’s estimates as of the date of this press release. Although we may choose to update these forward-looking statements at some time in the future, we assume no obligation to do so, even if subsequent events change our views, except as required by applicable law. These forward-looking statements should not be taken to represent our views as of any date subsequent to the date of this press release.

Multiclonics®, Biclonics® and Triclonics® are registered trademarks of Merus NV

CONTACT: Investor and Media Inquiries: Sherri Spear Merus N.V. VP Investor Relations and Corporate Communications 617-821-3246 [email protected] Kathleen Farren Merus N.V. IR/Corp Comms 617-230-4165 [email protected]


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