Merus N.V.

Today we will be taking you through the Phase 2 interim clinical data of pitothemptomab with pembrolizumab in first-line recurrent metastatic head and neck squamous cell carcinoma. This will include the data in the abstract published today on the American Society of Clinical Oncology, or ASCO's, website, as well as a summary of the data included in the poster presentation scheduled for Monday, June 2nd at the ASCO Annual Meeting in Chicago. This presentation is available on the Investors and Media page of our website. On this call, we will also make certain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These may include statements about our future expectations and plans, and events and circumstances, including about finances, intellectual property, projections about Marist's clinical development for 2025 and beyond, and the timing for plans and for meeting clinical and regulatory anticipated milestones related to pitocinthumab and our other biconics candidates. Each forward-looking statement is subject to risks and uncertainties that could cause actual results and events to differ materially from those projected in that statement. A more complete description of these and other material risks can be found in Meris's filings with the United States Securities and Exchange Commission, including its Form 10-Q for the period ended March 31st, 2025, which we filed with the FCC on May 7th, 2025. Merit does not undertake any obligation to update any forward-looking statements, whether as a result of new information, future events, or otherwise unless required to do so by law. Leading us through the agenda will be Dr. Bill Lundberg, Chief Executive Officer, Dr. Fabian Zorin, Chief Medical Officer, Peter Silverman, Chief Operating Officer in General Counsel, and Shannon Campbell, Chief Commercial Officer.

Good afternoon from Boston. This is an exciting time for MIRAPs.

Today's call will focus on the updated interim data for pitothemzumab in combination with pembrolizumab, or PEMBRO, as first-line therapy for PD-L1-positive recurrent metastatic tetanet cancer. We will discuss data which will also be presented at the ASCO 2025 annual meeting on June 2. Let me begin by providing a few remarks about our company and foundational technology platform that led to the generation of Pitaceptamab and our other clinical stage assets. Meris is an oncology-focused company with clinical assets of our own and multiple others we developed with our collaborators and licensees. We're also quite proud to have received our first approval by the US FDA for Bizangri last year. We believe this not only validates our innovative technology platforms, it also demonstrates our strong capabilities in oncology drug development and execution. We've been innovators in the field of multispecific antibodies for over a decade with our proprietary biquonics and triquonics antibody platforms that allow us to make multispecific antibodies like monoclonal antibodies. A single cell produces essentially a single multispecific antibody. This allows us to leverage the decades of experience making successful medicines from monoclonal antibodies, including high throughput screens, allowing biology to drive selection of the best molecules, manufacturability, large scale production from single producer cell lines, and the ability to rely upon tried and true CMC providers. And as fully human IgG1, our molecules are designed to have predictable in vivo behavior low immunogenicity, and consistent half-life, and can involve the FC domain engineering, like ADCC enhancement or stealth silencing for T-cell engagers, as well as compatibility for the generation of selective and potent antibody drug conjugates, or ADCs. These are powerful technology platforms, and while they don't guarantee success in the clinics, We believe by following tried and true approaches and reducing risk each step of the way, it can give us a better chance of being successful. Importantly, as the inventors of both our platform technologies and our clinical assets, we have an extensive and robust intellectual property patent estate covering our work. We used our Biclonix platform to address both growth and survival signals of cancer cells. We generated a large and diverse library of approximately 500 bispecific antibodies where each antibody targeted an EGFR family member on one arm and a Wnt pathway signaling molecule on the other arm. As shown in this cartoon, we evaluated this bispecific antibody library for the ability to potently inhibit the growth of cancer-derived as compared to normal tissue-derived organoids and more effectively than EGFR inhibition alone with cetuximab. From this work, we selected pitaceptamab, which binds with one arm to the well-established cancer target EGFR, and with the other arm, this new target called LGR5. We believe pitaceptamab acts through three distinct mechanisms. As shown on the left panel, pitaceptamab targets the well-established cancer antigen EGFR to prevent EGF ligand binding and growth signaling. The other arm targets LGR5. LGR5 is a protein expressed on normal adult tissue stem cells and stem cell-like cells within a cancer and is reported to be upregulated in a number of cancer types, including head and neck, colorectal, and other cancers. We've also observed an unexpected result shown in the middle panel. LGR5 acts by reducing the expression of certain proteins through internalization and degradation. In the presence of pitaceptamab, LGR5 also brings EGFR into the cell for degradation, essentially removing it from the cell. Finally, as shown on the panel on the right, pitaceptamab is ADCC-enhanced, designed to provide full engagement of the patient's own immune system against the cancer. This may be particularly relevant when combined with other immune-mediated mechanisms, for example, when blocking the PD1 T cell checkpoint with PEMBRO. We've also observed that blocking EGFR itself with pitaceptamab leads to increased expression of LGR5, which in turn may result in an even greater effect. Targeting LGR5 along with EGFR is a wholly new approach to cancer therapy. with promise to become a robust and potent way to treat cancer.