Genmab to Highlight New Data Evaluating Late-Stage Oncology Portfolio at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting

• First presentation of results from Phase 1/2 clinical trial of investigational rinatabart sesutecan (Rina-S^®) in patients with recurrent/advanced endometrial cancer
• Presentation of long-term follow-up data from analysis of Phase 1/2 EPCORE™ NHL-1 study of epcoritamab in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL)

Genmab A/S (Nasdaq: GMAB) announced today that it will present new research from its comprehensive development program evaluating its late-stage portfolio at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, taking place from May 30 to June 3 in Chicago, Illinois.

The presentations will include the first disclosure of results from a Phase 1/2 trial evaluating rinatabart sesutecan (Rina-S^®), an investigational folate receptor-alpha (FRa)-targeted, TOPO1-inhibor antibody-drug conjugate (ADC), in patients with recurrent/advanced endometrial cancer. Additionally, results from an analysis of the Phase 1/2 EPCORE NHL-1 study of epcoritamab, a T-cell–engaging bispecific antibody administered subcutaneously, including long-term follow-up in adult patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) who remain in complete response (CR) at 2 years, will be presented.

“Our presence at ASCO reflects our commitment to advancing our antibody science for patients in need of alternative treatment options, including women with endometrial cancers that have progressed following treatment with existing available therapies,” said Dr. Judith Klimovsky, Executive Vice President and Chief Development Officer of Genmab. “We’re particularly encouraged by Rina-S as a potential treatment option for endometrial cancer, one of the few cancers with rising mortality rates and few treatment options. Additionally, together with AbbVie, we are continuing our commitment to evaluating epcoritamab as a potential core therapy across B-cell malignancies.”

Investor Update at ASCO 2025

On Monday, June 2 at 4:00 PM CDT (5:00 PM EDT/11:00 PM CEST), Genmab will host a review of the Rina-S data presented at ASCO. The event will be virtual and webcast live. Details, including the webcast link and registration, will be available on https://ir.genmab.com/events-presentations. This meeting is not an official program of the ASCO Annual Meeting.

All abstracts accepted for presentation have been published and may be accessed online via the ASCO Meeting Library. Abstracts accepted for presentation at ASCO include:

Rinatabart sesutecan (Rina-S)

Epcoritamab

Non-Asset

The safety and efficacy of investigational products and uses have not been established.

About Rinatabart Sesutecan (Rina-S; GEN1184)

Rinatabart sesutecan (Rina-S; GEN1184) is a FRα-targeted, TOPO1 ADC, currently being evaluated for the potential treatment of ovarian cancer and other FRα-expressing cancers. A Phase 3 trial (RAINFOL^TM-02, NCT06619236) evaluating Rina-S in patients with platinum resistant ovarian cancer compared to treatment of investigator's choice is ongoing. In January 2024, the U.S. Food and Drug Administration granted Fast Track designation to Rina-S for the treatment of patients with FRα-expressing high-grade serous or endometrioid platinum-resistant ovarian cancer.

The safety and efficacy of rinatabart sesutecan has not been established. Please visit www.clinicaltrials.gov for more information.

About Epcoritamab

Epcoritamab is an IgG1-bispecific antibody created using Genmab's proprietary DuoBody^® technology and administered subcutaneously. Genmab's DuoBody-CD3 technology is designed to direct cytotoxic T cells selectively to elicit an immune response toward target cell types. Epcoritamab is designed to simultaneously bind to CD3 on T cells and CD20 on B cells and induces T-cell-mediated killing of CD20+ cells.ⁱ

Epcoritamab (approved under the brand name EPKINLY^® in the U.S. and Japan, and TEPKINLY^® in the EU) has received regulatory approval in certain lymphoma indications in several territories. Epcoritamab is being co-developed by Genmab and AbbVie as part of the companies' oncology collaboration. The companies share commercial responsibilities in the U.S. and Japan, with AbbVie responsible for further global commercialization. Both companies will pursue additional international regulatory approvals for the investigational R/R FL indication and additional approvals for the R/R DLBCL indication.

Genmab and AbbVie continue to evaluate the use of epcoritamab as a monotherapy, and in combination, across lines of therapy in a range of hematologic malignancies. This includes five ongoing Phase 3, open-label, randomized trials including a trial evaluating epcoritamab as a monotherapy in patients with R/R DLBCL compared to investigators choice chemotherapy (NCT04628494), a trial evaluating epcoritamab in combination with R-CHOP in adult patients with newly diagnosed DLBCL (NCT05578976), a trial evaluating epcoritamab in combination with rituximab and lenalidomide (R2) in patients with R/R FL (NCT05409066), a trial evaluating epcoritamab in combination with rituximab and lenalidomide (R2) compared to chemoimmunotherapy in patients with previously untreated FL (NCT06191744), and a trial evaluating epcoritamab in combination with lenalidomide compared to chemoimmunotherapy in patients with R/R DLBCL (NCT06508658). The safety and efficacy of epcoritamab has not been established for these investigational uses. Please visit www.clinicaltrials.gov for more information.

EPKINLY^® (epcoritamab-bysp) U.S. INDICATIONS & IMPORTANT SAFETY INFORMATION

What is EPKINLY?

EPKINLY is a prescription medicine used to treat adults with certain types of diffuse large B-cell lymphoma (DLBCL), high-grade B-cell lymphoma, or follicular lymphoma (FL) that has come back or that did not respond to previous treatment after receiving 2 or more treatments. EPKINLY is approved based on patient response data. Studies are ongoing to confirm the clinical benefit of EPKINLY. It is not known if EPKINLY is safe and effective in children.

IMPORTANT SAFETY INFORMATION

Important Warnings—EPKINLY can cause serious side effects, including:

• Cytokine release syndrome (CRS), which is common during treatment with EPKINLY and can be serious or lifethreatening. To help reduce your risk of CRS, you will receive EPKINLY on a step-up dosing schedule (when you receive 2 or 3 smaller step-up doses of EPKINLY before your first full dose during your first cycle of treatment), and you may also receive other medicines before and for 3 days after receiving EPKINLY. If your dose of EPKINLY is delayed for any reason, you may need to repeat the step-up dosing schedule.
• Neurologic problems that can be life-threatening and lead to death. Neurologic problems may happen days or weeks after you receive EPKINLY.

People with DLBCL or high-grade B-cell lymphoma should be hospitalized for 24 hours after receiving their first full dose of EPKINLY on day 15 of cycle 1 due to the risk of CRS and neurologic problems.

Tell your healthcare provider or get medical help right away if you develop a fever of 100.4°F (38°C) or higher; dizziness or lightheadedness; trouble breathing; chills; fast heartbeat; feeling anxious; headache; confusion; shaking (tremors); problems with balance and movement, such as trouble walking; trouble speaking or writing; confusion and disorientation; drowsiness, tiredness or lack of energy; muscle weakness; seizures; or memory loss. These may be symptoms of CRS or neurologic problems. If you have any symptoms that impair consciousness, do not drive or use heavy machinery or do other dangerous activities until your symptoms go away.

EPKINLY can cause other serious side effects, including:

• Infections that may lead to death. Your healthcare provider will check you for signs and symptoms of infection before and during treatment and treat you as needed if you develop an infection. You should receive medicines from your healthcare provider before you start treatment to help prevent infection. Tell your healthcare provider right away if you develop any symptoms of infection during treatment, including fever of 100.4°F (38°C) or higher, cough, chest pain, tiredness, shortness of breath, painful rash, sore throat, pain during urination, or feeling weak or generally unwell.
• Low blood cell counts, which can be serious or severe. Your healthcare provider will check your blood cell counts during treatment. EPKINLY may cause low blood cell counts, including low white blood cells (neutropenia), which can increase your risk for infection; low red blood cells (anemia), which can cause tiredness and shortness of breath; and low platelets (thrombocytopenia), which can cause bruising or bleeding problems. Your healthcare provider will monitor you for symptoms of CRS, neurologic problems, infections, and low blood cell counts during treatment with EPKINLY.

Your healthcare provider may temporarily stop or completely stop treatment with EPKINLY if you develop certain side effects.

Before you receive EPKINLY, tell your healthcare provider about all your medical conditions, including if you have an infection, are pregnant or plan to become pregnant, or are breastfeeding or plan to breastfeed. If you receive EPKINLY while pregnant, it may harm your unborn baby. If you are a female who can become pregnant, your healthcare provider should do a pregnancy test before you start treatment with EPKINLY and you should use effective birth control (contraception) during treatment and for 4 months after your last dose of EPKINLY. Tell your healthcare provider if you become pregnant or think that you may be pregnant during treatment with EPKINLY. Do not breastfeed during treatment with EPKINLY and for 4 months after your last dose of EPKINLY.

In DLBCL or high-grade B-cell lymphoma, the most common side effects of EPKINLY include CRS, tiredness, muscle and bone pain, injection site reactions, fever, stomach-area (abdominal) pain, nausea, and diarrhea. The most common severe abnormal laboratory test results include decreased white blood cells, decreased red blood cells, and decreased platelets.

In follicular lymphoma the most common side effects of EPKINLY include injection site reactions, CRS, COVID-19, tiredness, upper respiratory tract infections, muscle and bone pain, rash, diarrhea, fever, cough, and headache. The most common severe abnormal laboratory test results include decreased white blood cells and decreased red blood cells.

These are not all of the possible side effects of EPKINLY. Call your doctor for medical advice about side effects. You are encouraged to report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch or to Genmab US, Inc. at 1-855-4GENMAB (1-855-443-6622).

Please see Medication Guide, including Important Warnings.

Globally, prescribing information varies; refer to the individual country product label for complete information.

About Genmab

Genmab is an international biotechnology company with a core purpose of guiding its unstoppable team to strive toward improving the lives of patients with innovative and differentiated antibody therapeutics. For more than 25 years, its passionate, innovative and collaborative team has invented next-generation antibody technology platforms and leveraged translational, quantitative and data sciences, resulting in a proprietary pipeline including bispecific T-cell engagers, antibody-drug conjugates, next-generation immune checkpoint modulators and effector function-enhanced antibodies. By 2030, Genmab’s vision is to transform the lives of people with cancer and other serious diseases with knock-your-socks-off (KYSO) antibody medicines^®.

Established in 1999, Genmab is headquartered in Copenhagen, Denmark, with international presence across North America, Europe and Asia Pacific. For more information, please visit Genmab.com and follow us on LinkedIn and X.

This Media Release contains forward looking statements. The words “believe,” “expect,” “anticipate,” “intend” and “plan” and similar expressions identify forward looking statements. Actual results or performance may differ materially from any future results or performance expressed or implied by such statements. The important factors that could cause our actual results or performance to differ materially include, among others, risks associated with preclinical and clinical development of products, uncertainties related to the outcome and conduct of clinical trials including unforeseen safety issues, uncertainties related to product manufacturing, the lack of market acceptance of our products, our inability to manage growth, the competitive environment in relation to our business area and markets, our inability to attract and retain suitably qualified personnel, the unenforceability or lack of protection of our patents and proprietary rights, our relationships with affiliated entities, changes and developments in technology which may render our products or technologies obsolete, and other factors. For a further discussion of these risks, please refer to the risk management sections in Genmab’s most recent financial reports, which are available on www.genmab.com and the risk factors included in Genmab’s most recent Annual Report on Form 20-F and other filings with the U.S. Securities and Exchange Commission (SEC), which are available at www.sec.gov. Genmab does not undertake any obligation to update or revise forward looking statements in this Media Release nor to confirm such statements to reflect subsequent events or circumstances after the date made or in relation to actual results, unless required by law.

Genmab A/S and/or its subsidiaries own the following trademarks: Genmab^®; the Y-shaped Genmab logo^®; Genmab in combination with the Y-shaped Genmab logo^®; HuMax^®; DuoBody^®; HexaBody^®; DuoHexaBody^®, HexElect^® and KYSO^®. EPCORE^®, EPKINLY^®, TEPKINLY^® and their designs are trademarks of AbbVie Biotechnology Ltd.

ⁱ Engelberts PJ, et al. DuoBody-CD3xCD20 Induces Potent T-Cell-Mediated Killing of Malignant B Cells in Preclinical Models and Provides Opportunities for Subcutaneous Dosing. EBioMedicine. 2020;52:102625. doi: 10.1016/j.ebiom.2019.102625.

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