Vididencel

Preparations for pivotal-stage readiness of vididencel in AML on trackThe hard work of the Mendus team to advance the company’s lead product vididencel in acute myeloid leukemia (AML) continued to pay off during the fourth quarter of 2024. In December, we presented positive updated survival data of the ongoing ADVANCE II Phase 2 trial at ASH, demonstrating that the majority of patients treated remained alive at 41.8 months median follow-up. Also in Q4, we received positive EMA and FDA feedback endorsing our registration trial preparations. We successfully advanced our manufacturing alliance for the large-scale production of vididencel. The progress realized during the quarter keeps us on track to achieve pivotal-stage readiness of vididencel in AML as our lead program in the second half of 2025. Erik Manting, Ph.D.Chief Executive Officer Significant events of Q4 2024 Net sales for the period amounted to KSEK – (-) Result for the period amounted to KSEK -31,515 (-41,165) Earnings and diluted earnings per share totalled SEK -0.63 (-0.95*) Cash runway extended until beginning of 2026 versus earlier guidance until Q4 2025 Mendus presented preclinical data supporting the combination of its intratumoral primer ilixadencel with the immune checkpoint inhibitor avelumab at the 39th annual meeting of the Society for Immunotherapy of Cancer (SITC). Mendus announced that the members of the Nomination Committee for the 2025 Annual General Meeting were appointed. The Nomination Committee consists of Erik Esveld, appointed by Van Herk Investments B.V, Karl Elmqvist, appointed by Flerie Invest AB, and Mats Andersson, appointed by Holger Blomstrands Byggnads AB. Mendus presented positive survival data from the ongoing ADVANCE II Phase 2 trial at the ASH 2024 conference. The data showed that the majority of AML patients treated with vididencel remain alive and disease-free in long-term follow-up, with a median follow-up of 41.8 months. Mendus also presented two preclinical abstracts during the ASH 2024 conference. The first abstract demonstrated synergies between vididencel and the combination of venetoclax and azacitidine, two backbone drugs in the treatment of AML, with venetoclax having a direct synergistic effect on vididencel’s mode of action. The second abstract supports the potential use of vididencel in the treatment of chronic myeloid leukemia (CML). Mendus reported positive topline data from the ALISON Phase 1 clinical trial with vididencel in ovarian cancer. The data confirmed that vididencel stimulates immune responses against ovarian cancer antigens, as a potential basis for an effective anti-tumor response, and the strong safety profile for vididencel. Mendus announced that Institut Bergonié was no longer in a position to study Mendus’ intratumoral immune primer ilixadencel in soft tissue sarcomas as part of the REGOMUNE trial, because third party funding for the trial had been terminated. Significant events after end of reporting period Mendus announced a summary of the feedback received from FDA and EMA in the fourth quarter of 2024. The feedback is supportive of the preparations for a registration trial with vididencel in AML. Financial summary * The comparative numbers recalculated taking into account the reverse split, 20:1 The full report is attached as PDF and is available on the company’s website: https://mendus.com/investors/financial-reports/ Webcast investor call, February 13, 08.30 CETThe company will host a live presentation and business update today at 08.30 CET. The presentation will be held in English and includes a Q&A session. If you wish to participate via webcast please use the link below.https://mendus.events.inderes.com/q4-report-2024/register If you wish to participate and ask questions via teleconference, please register on the link below. After registration you will be provided phone numbers and a conference ID to access the conference.https://conference.inderes.com/teleconference/?id=5004794 For more information, please contact:Erik MantingChief Executive OfficerE-mail: ir@mendus.com About Mendus AB (publ) Mendus is dedicated to changing the course of cancer treatment by addressing tumor recurrence and improving long-term survival for cancer patients, while preserving health and quality of life. We leverage our understanding of dendritic cell biology to develop an advanced clinical pipeline of immunotherapies which combine clinical efficacy with a benign safety profile. Based in Sweden and The Netherlands, Mendus is publicly traded on the Nasdaq Stockholm under the ticker IMMU.ST. https://www.mendus.com/ AttachmentsMendus Q4 2024 ENG 02 13 FinalMendus AB Year-end Report 2024

Press Release Stockholm, Sweden, December 18, 2024 Mendus AB (“Mendus” publ; IMMU.ST), a biopharmaceutical company focused on immunotherapies targeting tumor recurrence, announces positive topline data from the ALISON Phase 1 clinical trial with its lead product vididencel in ovarian cancer. The data collected from all 17 patients treated confirm that vididencel stimulates immune responses against ovarian cancer antigens, as a potential basis for an effective anti-tumor response. The strong safety profile for vididencel was confirmed. The ALISON trial is a single-center Phase 1 trial carried out by the University Medical Center Groningen, The Netherlands (UMCG). The trial explores the potential of vididencel to induce clinically relevant immune responses in high-grade serous ovarian carcinoma (HGSC). Mendus and UMCG had earlier reported at the ESMO Gynaecological Cancers conference in June 2024 that 10 patients treated with vididencel in the ALISON trial had stable disease and 7 patients had imaging-confirmed recurrence at week 22. Based on the updated analysis of samples collected from all patients treated with vididencel, a vaccine-induced immune response (VIR) against one or more tumor antigens that are regularly upregulated in HGSC was observed in 12 out of 17 patients (71%). The observed immune responses to different tumor antigens provides a potential basis for an effective anti-tumor response. Stable disease at week 22 was observed in 2 out of 5 patients (40%) without VIR, whereas the majority of patients with VIR had stable disease (8 out of 12 patients, or 67%). “Ovarian cancer is the deadliest gynaecological cancer, particularly due to its high recurrence rate, with recurring tumors being generally unresponsive to earlier lines of treatment.” said Dr Hans Nijman, Professor Obstetrics and Gyneacology and Head of Immuno-oncology at UMCG. “Active immunotherapies like vididencel, which aim to improve immune responses against residual disease, therefore hold promise as a novel treatment option to improve disease-free and overall survival of ovarian cancer patients after primary treatment. We look forward to further evaluate the potential clinical benefit of vididencel based on long-term follow-up of patients treated in the ALISON trial.” The ALISON trial confirmed the strong safety profile of vididencel, indicating only mild adverse reactions, predominantly at the site of injection. Long-term follow-up of patients treated with vididencel as part of the ALISON trial is ongoing, with a next read-out based on 2-year follow-up expected in 2025Q4. For more information, please contact: Erik MantingChief Executive OfficerE-mail: ir@mendus.com About Mendus AB (publ) Mendus is dedicated to changing the course of cancer treatment by addressing tumor recurrence and improving long-term survival for cancer patients, while preserving health and quality of life. We leverage our understanding of dendritic cell biology to develop an advanced clinical pipeline of immunotherapies which combine clinical efficacy with a benign safety profile. Based in Sweden and The Netherlands, Mendus is publicly traded on the Nasdaq Stockholm under the ticker IMMU.ST. https://www.mendus.com/ Attachments241218 ALISON Topline ENG