IBI363's Phase 3 Expansion: Novel Mechanism, No Precedent, High-Stakes Bet on IL-2 Overcoming IO Resistance

Innovent Expands MarsLight-11 Trial to Non-Squamous NSCLC

Innovent Biologics has expanded its global Phase III MarsLight-11 trial for IBI363 (TAK-928) to include non-squamous non-small cell lung cancer (NSCLC) patients, in addition to its initial focus on squamous NSCLC. The multicentre, randomised, controlled study will now feature two substudies, assessing IBI363 as a monotherapy against docetaxel in patients with advanced or metastatic NSCLC whose disease has progressed after chemotherapy and immunotherapy. IBI363, an alpha-biased IL-2/PD-1 bispecific fusion protein, is co-developed by Innovent and Takeda and has received two US FDA Fast Track designations and three China NMPA Breakthrough Therapy designations.

• The global Phase III MarsLight-11 trial, initially focused on squamous NSCLC, has been expanded to include non-squamous NSCLC patients whose disease has progressed following chemotherapy and immunotherapy. This multicentre, randomised, controlled study will now comprise two distinct substudies, evaluating IBI363 as a monotherapy in comparison to docetaxel for advanced or metastatic NSCLC.
• IBI363, also known as TAK-928, is a potential first-in-class alpha-biased IL-2/PD-1 bispecific fusion protein. Its mechanism of action involves blocking the PD-1/PD-L1 pathway while selectively activating the IL-2 pathway, designed to reduce toxicity through targeted binding to specific IL-2 receptors. The drug is also being investigated in other global clinical trials, including pivotal Phase II for melanoma and Phase III for colorectal cancer.
• IBI363 has garnered significant regulatory recognition, receiving two Fast Track designations from the US FDA and three Breakthrough Therapy designations from the China NMPA. The drug is being co-developed globally by Innovent and Takeda, with their collaboration commencing in October 2025. Innovent and Takeda share co-development and commercialisation plans for the US market, while Takeda manages markets outside the US and Greater China.

MarsLight-11 Expansion: Trial Design for Advanced NSCLC

Several recent trials have evaluated novel therapeutic strategies across the NSCLC treatment continuum — from neoadjuvant and adjuvant settings to advanced/metastatic disease — spanning immunotherapy, targeted agents, and multimodal interventions.

IBI363's Novel Bispecific Mechanism for Advanced NSCLC

Several mechanistic strategies have emerged over the past three years to address the persistent challenges of immune evasion, acquired resistance, and residual disease in NSCLC. These approaches span immune checkpoint biology, oncogenic fusion-driven resistance, and novel cellular therapies, reflecting a broad diversification of the treatment landscape.

• TIGIT Checkpoint Blockade: Tiragolumab, a monoclonal antibody targeting TIGIT, inhibits CD155-mediated T cell suppression and enhances cytotoxic T lymphocyte and NK cell activity. Combined with PD-1/PD-L1 inhibitors, this dual blockade demonstrated an objective response rate of 37% versus 21% with PD-L1 inhibitor monotherapy in the CITYSCAPE trial. Bispecific antibodies targeting TIGIT/PD-1 and TIGIT/PD-L1 simultaneously are under active investigation to further amplify antitumor immunity.

• Dual EGFR-MET and HER3-Directed Combination Strategies: Amivantamab, an EGFR-MET bispecific antibody, combined with patritumab deruxtecan, a HER3 antibody-drug conjugate, has shown synergistic efficacy against osimertinib-resistant NSCLC cell lines. The combination polarized macrophages toward the M1 phenotype in vivo, remodeling the tumor immune microenvironment in a manner unfavorable to tumor growth.

• RET Fusion Inhibition as a Resistance Bypass Mechanism: RET fusions — including CCDC6, KIF5B, and NCOA4 partners — are emerging as acquired resistance mechanisms in EGFR-mutated NSCLC following EGFR-TKI therapy, with a median time to detection of 11.4 months. Combined osimertinib and pralsetinib demonstrated clinical benefit in patients harboring co-occurring EGFR mutations and RET fusions, with progression-free survival ranging from 3.9 to 10.5 months in this setting.

• PDK1 Inhibition to Overcome EGFR C797S-Driven Resistance: The EGFR C797S mutation drives osimertinib resistance through elevated PDK1 expression and enhanced glycolysis via the EGFR/AKT/HIF-1α axis. Combining osimertinib with the PDK1 inhibitor leelamine successfully overcame this resistance in allograft models, and CRISPR-mediated PDK1 knockout inhibited tumor formation in xenograft models.

• TROP2-Directed CAR-T Cell Therapy Targeting Drug-Tolerant Persisters: Drug-tolerant persister cells in EGFR-mutated NSCLC exhibit enriched TROP2 surface expression following osimertinib treatment. A single infusion of sacituzumab-based TROP2-directed CAR-T cells significantly prolonged relapse-free survival in vivo, with evidence of cure, outperforming the TROP2 ADC sacituzumab govitecan administered at the point of minimal residual disease.

Addressing Unmet Needs in Advanced NSCLC Post-Treatment

Recent literature highlights several distinct patient populations in NSCLC where current treatment strategies remain inadequate, driving active clinical and translational investigation across molecular subtypes, CNS disease, and biomarker-negative cohorts.

• EGFR Exon 20 Insertion Mutations: This molecularly distinct subgroup carries a high rate of CNS involvement — 36.25% of patients experience CNS progression, with 7.5% developing leptomeningeal disease. Despite amivantamab being registered for progression after platinum-based chemotherapy, the need for CNS-penetrant treatment strategies remains a critical gap, as CNS progression did not significantly impact median OS (45.3 months with CNS progression vs. 47.8 months without; hazard ratio 1.21, 95% CI: 0.66–2.23, P=0.54), underscoring the complexity of managing this population.

• Co-mutated TP53 in EGFR-Mutant NSCLC: Concurrent TP53 mutations represent an emerging resistance-facilitating factor. In EGFR ins20 patients, co-TP53 mutation was associated with a lower median OS of 31.6 months (20.4–NE) compared to 47.8 months (42.8–72.3) in TP53 wild-type patients (hazard ratio 1.79, 95% CI: 0.89–3.60, P=0.11), identifying this co-mutation as a population requiring tailored therapeutic strategies.

• PD-L1 Negative NSCLC: Patients with tumor proportion score <1% represent a persistently underserved population. In a real-world multicenter retrospective study, ICI-containing regimens did not demonstrate significantly improved OS (median 23.8 vs. 14.9 months, P=0.87) or PFS (median 7.8 vs. 6.6 months, P=0.20) compared to chemotherapy alone, despite higher overall response rates (50.0% vs. 34.4%) and disease control rates (81.5% vs. 65.6%) in the ICI group. High tumor mutational burden and positive tumor-infiltrating lymphocytes have been identified as potential complementary biomarkers to guide treatment selection in this group.

• ALK-Rearranged NSCLC with CNS Progression on CNS-Penetrant TKIs: Even among patients receiving CNS-penetrable ALK TKIs (alectinib, lorlatinib, brigatinib, ensartinib), 37% developed CNS progression. Leptomeningeal progression and concurrent systemic progression represent particularly challenging scenarios; TKI alteration (switch or dose increase) was a feasible salvage strategy, though median intracranial progression-free survival did not differ significantly between TKI-altered and TKI-unaltered groups (P=0.21), highlighting the absence of a validated standard of care.

• Histological Transformation as an Immunotherapy Resistance Mechanism: NSCLC patients — including those with KRAS mutations — who undergo small cell lung cancer transformation following ICI therapy represent a rare but critically underserved population. Transformed patients exhibit poor prognosis, and systematic data on clinical characteristics, molecular basis, and subsequent treatment strategies remain lacking, with dynamic NSE monitoring and repeat biopsy identified as essential but underutilized tools.

IBI363's Expanded Trial Targets Critical Unmet Need in Advanced NSCLC

Innovent Biologics' decision to expand its Phase III MarsLight-11 trial for IBI363 (TAK-928) to encompass non-squamous non-small cell lung cancer (NSCLC) patients marks a pivotal moment for this novel therapeutic. This move significantly broadens the potential reach of IBI363, an alpha-biased IL-2/PD-1 bispecific fusion protein, into a patient population desperately in need of new options.

The trial focuses on advanced or metastatic NSCLC patients whose disease has progressed after both chemotherapy and prior immunotherapy. This is a particularly challenging group, as existing evidence indicates that patients who have failed initial immune checkpoint inhibitors and chemotherapy often have limited subsequent treatment avenues. For instance, studies exploring other agents in this post-immunotherapy setting have shown modest efficacy, highlighting the high bar IBI363 must clear. The strategic implication is clear: if successful, IBI363 could establish a new standard of care, offering a differentiated mechanism of action beyond current options like docetaxel.

However, several risks warrant consideration. The inherent complexity of an alpha-biased IL-2/PD-1 bispecific fusion protein means its safety profile, particularly regarding immune-related adverse events, will be closely scrutinized. Furthermore, the nuanced pharmacology of immune agonists suggests that optimal dosing can be intricate; research on similar co-stimulatory agonists indicates that efficacy might not be linear with dose, sometimes exhibiting bell-shaped responses where higher concentrations could lead to reduced activity. Navigating these complexities to achieve a favorable risk-benefit profile will be crucial for IBI363's clinical success and its ability to address this critical unmet need in advanced NSCLC.