Abstract CT259: Results from monotherapy dose escalation of MDNA11, a long-acting IL-2 superkine, in a phase 1/2 trial show evidence of single-agent activity in advanced solid tumors

Abstract

Abstract Background: MDNA11 is an albumin-fused ‘beta-enhanced not-alpha’ IL-2 agonist engineered to preferentially expand and activate CD8+ T and NK cells with minimal impact on Tregs. The ABILITY-1 (A Beta-only IL-2 ImmunoTherapY) is a global Phase 1/2 study evaluating the safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary clinical activity of MDNA11, both as single agent and in combination with a PD-1 inhibitor, in pre-treated patients with advanced solid tumors. Method: The ABILITY-1 study (NCT05086692) comprises monotherapy dose escalation/evaluation with a modified 3+3 design (enrollment complete); monotherapy dose expansion (enrolling); combination with pembrolizumab dose escalation (enrolling) followed by combination expansion. Thirty participants were enrolled in the monotherapy cohorts (3, 10, 30, 60, 90, and 120 μg/kg, IV, Q2W): 23 in dose escalation and 7 in dose evaluation. To enhance tolerability, step-up dosing with 2 or 3 priming doses was implemented starting at 60 μg/kg. Primary endpoints were incidence and severity of adverse events (AEs) and secondary endpoints included PK, PD, and tumor response (RECIST 1.1 and iRECIST). Results: As of December 22, 2023, 30 patients were enrolled in dose-escalation/evaluation, comprising 16 melanoma, 3 NSCLC, 3 PDAC, 2 RCC, 2 sarcoma, 2 ovarian cancer, 1 tonsillar squamous cell carcinoma and 1 gastro-esophageal adenocarcinoma. No dose-limiting toxicities (DLTs) were observed. Most common treatment related AEs were infusion-related reactions (53.3%), primarily grade 1-2, encompassing pyrexia (43.3%), nausea (33.3%), chills (33.3%), hypotension (30%), and fatigue (26.6%) that resolved within 48-72 hours. PK analysis showed sustained dose-dependent increase in serum concentration of MDNA11 with repeat doses. PD evaluation showed robust and durable dose-dependent increase in lymphocyte counts without eosinophilia. Immune effector cells, particularly CD8+ T cells, showed durable expansion with evidence of activation markers (CD25, ICOS and OX40) peaking at the 90 μg/kg dose. Single-agent anti-tumor activity was evident among 26 evaluable patients with confirmed partial responses (PRs) in a PDAC (MSI-H) patient (60 μg/kg cohort) and a melanoma patient (90 μg/kg cohort) as well as 8 (30.7%) stable disease (SD) including 3 melanoma patients with durable SD (>6 months, >8 months, >1.5 years). Based on the combined safety, PK, PD and preliminary anti-tumor activity, a recommended dose for expansion (RDE) of 90 μg/kg (preceded by priming doses of 30 and 60 μg/kg; Q2W) was selected for the ongoing monotherapy dose expansion of the ABILITY-1 study. Conclusions: MDNA11 was well-tolerated with no DLTs observed at all dose levels up to 120 μg/kg. With study currently ongoing, single agent clinical activity was evident with an ORR of 7.7% and Clinical Benefit Rate (CBR) of 19.2% (2 PRs + 3 SDs > 6 months) in dose escalation to date. Monotherapy dose expansion at 90 μg/kg and combination dose escalation with pembrolizumab are enrolling. Citation Format: Victoria G. Atkinson, Jesus F. Antras, Philippe Bedard, Warren Brenner, Jacqueline Brown, Charlotte R. Lemech, Peter Lloyd, Kim Margolin, Matthen Mathew, John J. Park, Sajeve Thomas, Przemyslaw Twardowski, Humphrey Gardner, Amy Prawira, Melissa Coello, Walead Ebrahimimizadeh, Minh D. To, Rosemina Merchant, Sudhir Madduri Karanam, Arash Yavari, Lillian L. Siu, Hussein A. Tawbi, Paolo A. Ascierto. Results from monotherapy dose escalation of MDNA11, a long-acting IL-2 superkine, in a phase 1/2 trial show evidence of single-agent activity in advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT259.