e14583 Background: Interleukin (IL)-12 is a potent immunomodulatory cytokine demonstrating robust antitumor activity in multiple preclinical studies and potent immune-stimulating potential in humans. However, systemic delivery of IL-12 can result in life-threatening toxicity and therefore has shown limited efficacy at doses that can be safely administered. ABO2011 is a human IL-12 mRNA encapsulated in lipid nanoparticle and has been developed to be more effective and less toxic through the use of novel delivery technology and intratumoral injection. Methods: This phase I trial enrolled adults with advanced solid tumors who failed available standard treatments (NCT05392699). The trial was designed to primarily evaluate the safety of ABO2011 in single-dose cohorts and multiple-dose cohorts using “3+3” dose escalation approach. Patients (pts) would receive intratumoral ABO2011 at either a single dose, QW with 3 doses overall, every 3 weeks (Q3W) or QW followed by Q3W. Results: As of 09 December 2023, a total of 20 pts were enrolled and received at least one dose of ABO2011 at 4 μg single dose, 4 μg QW for 3 times, 12 μg single dose, 12 μg QW for 3 times followed by Q3W, 24 μg Q3W and 48 μg Q3W. Seventeen (85%) pts experienced treatment-related adverse events (TRAEs), and all were grade 1 or 2, including pyrexia (35%), pain (25%), and gamma-glutamyl transferase increased (25%). There were no dose-limiting toxicities or treatment-related SAEs reported and no TRAEs leading to treatment discontinuation. Of the 17 evaluable pts per RECISIT v1.1, 5 maintained stable disease, and the progression free survivals achieved 6.0 months, 5.6 months and 4.1 months for pts with colorectal cancer (6 th line), non-small cell lung cancer (5 th line) and pancreatic cancer (4 th line), respectively. Peripheral blood IL-12 and IFN-γ levels increased and peaked at 24 hours and 48 hours after dosing, respectively, indicating expression of IL-12 and subsequent induction of IFN-γ after ABO2011 administration. Dose-dependent elevation of CXCL9, CXCL10, CXCL11 in peripheral blood was observed, consistent with the activation of downstream pathway of IFN-γ. CD8 T cells infiltration and PD-L1 expression were increased in tumor microenvironment (TME) at day 7, and further RNA sequencing analysis revealed increase of activated CD8 T cell and antigen processing and presentation after study treatment, suggesting the regulation of TME by ABO2011 and supporting the combination with PD-1(L1) inhibitor. Conclusions: Intratumoral ABO2011 was safe and well-tolerated in pts with advanced solid tumors. The pharmacodynamic changes were as expected. Promising preliminary antitumor activities of the single agent and the pharmacodynamic profiles support further investigation of ABO2011 in combination with immune checkpoint inhibitor. Clinical trial information: NCT05392699 .

Preliminary safety, antitumor activity, and pharmacodynamics of intratumoral ABO2011 (IL-12 mRNA) in patients with advanced solid tumors.