Medicenna Therapeutics Corp. announced that new clinical data from the Phase 1 monotherapy dose escalation/evaluation portion of the Phase 1/2 ABILITY-1 (ABeta-only IL-2 ImmunoTherapY) study evaluating MDNA11, the only long-acting, ?beta-enhanced not-alpha? interleukin-2 (IL-2) super-agonist in clinical development, in patients with advanced solid tumors, were presented at the 38th Annual Meeting of the Society for Immunotherapy of Cancer (SITC) held in San Diego, CA, on November 4th, 2023.

Favorable safety profile: No dose limiting toxicity (DLT) reported and no evidence of vascular leak syndrome (VLS). Vast majority (95.6%) of treatment-related adverse events (TRAEs) were of grade 1-2 severity and resolved within 48 hours; grade 3 TRAEs mainly constituted transient LFT elevations; no grade 4 or 5 events were reported. Encouraging single-agent anti-tumor activity at doses of 60 ug/kg (N = 15): Partial response reported in 2 patients with aggressive tumor types A patient with metastatic pancreatic ductal adenocarcinoma (PDAC; MSI-H), who had previously failed on multiple systemic therapies and exhibited primary resistance to immune checkpoint inhibitors, experienced remarkable response to MDNA11 (60 ug/kg) with baseline target lesions and non-target lesions showing deepening shrinkage on successive imaging scans.

Following return from a 7 week vacation, a single new lesion was observed and MDNA11 treatment was resumed. Prior to receiving one cycle of radiotherapy for the new lesion, complete resolution of initial 2 target and 1 non-target lesions was achieved. Patient continues on MDNA11 post radiotherapy.

A patient with cutaneous melanoma, who progressed on prior line of dual checkpoint inhibitors, treated with MDNA11 (90 ug/kg dose), showed a 70% reduction of the target lymph node lesion at week 12. Durable stable disease in 3 metastatic melanoma patients with concomitant reduction in tumor burden: Two patients with SD of >20 (acral melanoma) and >24 weeks (cutaneous melanoma) are continuing MDNA11 treatment in the 120 ug/kg cohort. One patient with cutaneous melanoma had SD for > 1.5 years having started MDNA11 at the 10 ug/kg dose with subsequent intra-patient dose escalations of 30, 60 and 90 ug/kg.

Potent proliferation of effector immune populations: Pharmacodynamic data showed robust and durable activation of effector immune cells, particularly CD8+ T cells (CD25+, OX40+), with minimal impact on the immunosuppressive Treg population. Recommended Dose for Expansion (RDE): Target dose of 90 ug/kg (following two step-up doses of 30 and 60 ug/kg) Q2W IV infusion was chosen for monotherapy expansion portion of the ABILITY-1 study. Monotherapy expansion part of ABILITY-1 is enrolling patients with metastatic melanoma, non-melanoma skin cancers (CSCC, MCC, and BCC) and MSI-H/dMMR tumors.