Alligator Bioscience Announces Two Presentations on Mitazalimab and ATOR-4066 at the AACR Annual Meeting 2024

1st Presentation supports dosing regimen for mitazalimab in combination with FOLFORINOX and improvement of antitumor response 2nd Presentation highlights potential of ATOR-4066 to induce tumor localized immune cell activation and strongly support further development of the candidate in clinical trials Lund, Sweden – Alligator Bioscience (Nasdaq Stockholm: ATORX) today announces the company will give two presentations, one on mitazalimab, a CD40 agonist, and one on ATOR-4066, a Neo-X-Prime® bispecific antibody (bsAb), at the Americal Association for Cancer Research (AACR) Annual Meeting, taking place April 5-10, 2024, in San Diego, California. The first presentation, entitled “Mitazalimab, a potent CD40 agonist in combination with FOLFIRINOX demonstrates changes consistent with increased immune activation in TME and peripheral blood in a preclinical pancreatic cancer tumor model”, provides further support to the unique dosing regimen chosen for the OPTIMIZE-1 Phase 2 study in first line metastatic pancreatic cancer, resulting in an increased tumoricidal immune profile, including a marked increase in effector CD8+ T cells in the tumor microenvironment. Taken together, these preclinical data provides a mechanistic explanation to the unprecedented DoR and OS observed in OPTIMIZE-1 and corroborates the previously reported associations between clinical response and T cell activation, highlighting the mitazalimab-specific contribution to tumor responses. Moreover, the presentation underlines the synergistic potential of this combination for an improved antitumor response compared to FOLFIRINOX alone. The second presentation, entitled “ATOR-4066, a Neo-X-Prime™ bispecific antibody targeting CD40 and CEACAM5, induces tumor localized immune cell activation in preclinical in vivo tumor model”, demonstrates that ATOR-4066 activates tumor infiltrating dendritic cells and macrophages resulting in increases in activated tumor infiltrating T cells, thus creating a pro-inflammatory tumor microenvironment leading to single-agent complete responses in translational tumor models. These data strongly support further development and clinical testing of ATOR-4066. “We are very pleased to be presenting data for two of our promising CD40-candidates at this year’s prestigious AACR Annual Meeting, which highlight the increasing strength and progress of our CD40 program,” said Søren Bregenholt, CEO of Alligator Bioscience. “The first presentation details further supporting evidence of the potential of our lead asset mitazalimab to provide significant clinical benefit to pancreatic cancer patients in combination with chemotherapy when compared to standard of care, as demonstrated in the outstanding top-line results from our OPTIMIZE-1 study. The second presentation suggests CD40 could be activated in a very selective manner, which would open the way to an even more targeted therapeutic approach. These data strongly support the further development of ATOR-4066 in clincial trials, which Alligator is currently working toward.” Poster Presentation Details Abstract Number: 2376 Title: Mitazalimab, a potent CD40 agonist in combination with FOLFIRINOX demonstrates changes consistent with increased immune activation in TME and peripheral blood in a preclinical pancreatic cancer tumor model Date/Time: April 8, 2024, 9:00 AM – 12:30 PM PT Session: PO.CL06.07 – Antibodies 1 Presenter: D. Gomez Jimenez, Translational Scientist, Alligator Bioscience Location: Poster Section 38, Poster Board 22 Abstract Number: 5309 Title: ATOR-4066, a Neo-X-Prime™ bispecific antibody targeting CD40 and CEACAM5, induces tumor localized immune cell activation in preclinical in vivo tumor model Date/Time: April 9, 2024, 1:30 PM – 5:00 PM PT Session: PO.IM01.17 – Immune Modulation Employing Agonist or Co-Stimulatory Approaches Presenter: Hampus Andersson, PhD Student, Alligator Bioscience Location: Poster Section 3, Poster Board 18 For further information, please contact: Søren Bregenholt, CEO E-mail: [email protected] Phone: +46 (0) 46 540 82 00 LifeSci Advisors Investor Relations Guillaume van Renterghem E-mail: [email protected] Phone: +41 (0) 76 735 01 31 About Alligator Bioscience Alligator Bioscience AB is a clinical-stage biotechnology company developing tumor-directed immuno-oncology antibody drugs. Alligator’s portfolio includes several promising drug candidates, with the CD40 agonist mitazalimab as its key asset. Furthermore, Alligator is co-developing ALG.APV-527 with Aptevo Therapeutics Inc., several undisclosed molecules based on its proprietary technology platform, Neo-X-Prime®, and novel drug candidates based on the RUBY® bispecific platform with Orion Corporation. Out-licensed programs include AC101/HLX22, in Phase 2 development, by Shanghai Henlius Biotech Inc. and an undisclosed target to Biotheus Inc. Alligator Bioscience’s shares are listed on Nasdaq Stockholm (ATORX) and is headquartered in Lund, Sweden. For more information, please visit alligatorbioscience.com.

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