Alligator Bioscience

• ATOR-1017, a potential best-in-class 4-1BB monoclonal antibody, demonstrates an excellent preclinical profile with a unique binding site on 4-1BB
• Preclinical data demonstrate ATOR-1017's strong safety profile and potent therapeutic anti-tumor effect in vivo both as monotherapy and in combination with anti-PD-1 treatment
• ATOR-1017 demonstrated excellent clinical profile as a potential best-in-class 4-1BB monoclonal antibody in recent Phase 1 dose-escalation study
• The data presented in the manuscript provides a strong preclinical foundation for further clinical development of ATOR-1017

Lund, Sweden – Alligator Bioscience (Nasdaq Stockholm: ATORX) today announces the publication of a scientific article highlighting the 4-1BB FcγR-conditional agonist antibody ATOR-1017, which is being developed as a tumor-directed therapy for advanced/metastatic cancer.

The publication in the journal Cancer Immunology, Immunotherapy demonstrates how the design, detailed binding epitope (binding site) on 4-1BB and molecular properties of ATOR-1017 translate into very potent activity both in vitro and in vivo, as monotherapy and in combination with anti-PD-1 treatment, while being well tolerated in preclinical models.

ATOR-1017 binds to a unique epitope on 4-1BB enabling the activation of T cells, including cells with an exhausted phenotype, and NK cells, in a cross-linking dependent, FcγR-conditional manner. This translates into a tumor-directed and potent anti-tumor therapeutic effect in vivo, which is further enhanced with anti-PD-1 treatment.

The full article, entitled "ATOR-1017, an Fc-gamma receptor conditional 4-1BB agonist designed for optimal safety and efficacy, activates exhausted T cells in combination with anti-PD-1", is available online via this link.

"The publication of this article in the renowned scientific journal Cancer Immunology, Immunotherapy is an important recognition of our research into 4-1BB as a target for cancer immunotherapy," said Søren Bregenholt, CEO of Alligator Bioscience. "The first generation of 4-1BB agonists were limited by poor efficacy and unacceptable safety profiles but the preclinical data presented in this article, and the results of our recent Phase 1 dose-escalation study, demonstrate how ATOR-1017 is both a potent 4-1BB agonist and a safe and well tolerated drug candidate with a significant therapeutic potential."

In September 2022, Alligator announced that its Phase 1 open-label dose-escalation study of ATOR-1017 in patients with histologically confirmed, advanced, and/or refractory solid cancer (NCT04144842) had successfully met its primary objective to investigate the safety and tolerability of ATOR-1017 at therapeutic doses. ATOR-1017 demonstrated excellent safety and tolerability at doses up to 900 mg and stable disease as the best tumor response confirmed its previously reported indications on clinical benefit.