Summit Therapeutics and Akeso's Harmoni-3 Trial Results Anticipated in H2 2026

Summit & Akeso's Harmoni-3 Trial Poised to Reshape NSCLC Treatment

Results from the global Harmoni-3 trial, evaluating the combination of ivonescimab and chemotherapy for frontline non-small cell lung cancer (NSCLC), are expected in the second half of 2026. This pivotal study aims to demonstrate superior efficacy in delaying disease progression and death compared to the current standard-of-care, Merck’s Keytruda plus chemotherapy. Earlier data from a similarly structured China-only trial showed the ivonescimab-chemo combination extended survival and controlled tumors longer. Success in Harmoni-3 could significantly impact NSCLC treatment and boost confidence in PD-1/VEGF inhibitors for other cancers. However, skepticism exists due to demographic differences between the China-only and global trials, particularly concerning patient age and post-progression care.

• The Harmoni-3 trial is a global, late-stage study evaluating ivonescimab in combination with chemotherapy as a frontline treatment for non-small cell lung cancer (NSCLC). Its primary objective is to definitively show that this novel regimen can help delay disease progression and death more effectively than the widely used Keytruda-chemo standard of care. Positive results from this trial could significantly alter the treatment landscape for NSCLC and potentially broaden the application of PD-1/VEGF inhibitors to other cancer types, marking a major advancement in oncology.
• Optimism for Harmoni-3 is partly driven by promising results from a prior, similarly designed trial conducted exclusively in China. In that study, the ivonescimab-chemo combination demonstrated extended survival and superior tumor control compared to a different immunotherapy-chemo pairing. These compelling findings were prominently featured at a major cancer research meeting, leading some analysts to anticipate a similar positive outcome for the global Harmoni-3 trial, despite the inherent challenges of replicating regional success on a global scale.
• Despite the encouraging China-only data, significant skepticism surrounds the Harmoni-3 trial, primarily due to critical differences in patient populations and study conduct. Critics highlight that the China trial enrolled younger patients and excluded those over 75, a demographic that constitutes a substantial portion of Keytruda users in the U.S. Furthermore, ivonescimab did not show clear benefit in patients aged 65-75 in the China study, raising concerns about its efficacy in older, more representative global patient cohorts and the translatability of the earlier results.

The Persistent Challenges in Frontline NSCLC Treatment

Despite significant therapeutic advances over the past decade, frontline NSCLC treatment continues to be constrained by fundamental biological, clinical, and systemic barriers. The heterogeneity of the disease — spanning actionable and non-actionable genomic landscapes, histologic subtypes, and patient populations — means that no single treatment paradigm achieves broad, durable benefit.

• Limited reach of targeted therapies: More than 75% of NSCLC cases lack an actionable gene aberration, restricting the applicability of precision oncology approaches. Fewer molecular data are available for squamous cell carcinoma compared to adenocarcinoma, further limiting therapeutic development in this subtype. Even when actionable mutations are identified, many tumors ultimately acquire resistance to targeted agents.

• Systemic undertreatment in older adults: Among older patients with metastatic NSCLC, 53.2% never received systemic therapy, with this proportion only minimally improving between 2006 and 2021. Of patients who died within 90 days of diagnosis — representing 39.8% of the total population — only 13.2% received any treatment. Notably, approximately one-fifth of patients with the most favorable clinical profiles still did not receive systemic therapy.

• Structural barriers to treatment access: Key drivers of undertreatment include lack of referral to oncology specialists (associated with a 30.3% lower treatment rate), absence of biomarker testing (17.8% lower rate), age over 80 years (15.4% lower rate), and NSCLC not otherwise specified histologic classification (12.8% lower rate compared to adenocarcinoma).

• Toxicity and mortality with aggressive regimens: Treatment-related mortality with intensive chemotherapy regimens (VIP-E/VIC-E) was 3% in limited-stage and 8% in extensive-stage NSCLC. Five-year survival in extensive-stage disease was 0% for both standard-dose and high-dose chemotherapy protocols, underscoring the inadequacy of cytotoxic intensification strategies.

• Immunotherapy combinations: efficacy-toxicity trade-offs: Neoadjuvant nivolumab plus ipilimumab demonstrated substantial toxicity, with 67% of patients experiencing treatment-related adverse events, 33% experiencing grade ≥3 events, and 33% experiencing biopsy-confirmed tumor progression that precluded definitive surgery. One patient died postoperatively due to acute respiratory distress syndrome. The absence of validated predictive biomarkers to enrich for response remains a critical unmet need for neoadjuvant immunotherapy combinations.

• Unmet efficacy with combination strategies: The addition of bevacizumab and erlotinib to chemotherapy showed no statistically significant improvement in survival or time to progression compared to chemotherapy alone over four years of follow-up. Similarly, camrelizumab plus chemotherapy was not considered cost-effective versus chemotherapy alone in China, with an incremental cost-effectiveness ratio of $67,416.50 per quality-adjusted life year — exceeding the willingness-to-pay threshold of $31,500.

• Drug resistance and payload limitations: Topoisomerase II inhibitors such as etoposide have demonstrated limited efficacy in NSCLC, with drug resistance and systemic toxicity representing persistent obstacles. These limitations extend to emerging modalities, including antibody-drug conjugates, where acquired resistance and on-target/off-tumor toxicity remain active areas of investigation requiring improved patient selection strategies.

Unpacking the Pivotal Harmoni-3 Trial Design

The pivotal trials in non-small cell lung cancer (NSCLC) span a broad range of therapeutic modalities — from EGFR-TKIs and ALK inhibitors to immunotherapy combinations and antibody-drug conjugates — each employing distinct design parameters tailored to molecular subgroups. Across studies, progression-free survival (PFS) is the most consistently used primary endpoint, with overall survival (OS) and objective response rate (ORR) serving as key secondary measures. The following table consolidates the design parameters and endpoints from the most clinically relevant trials identified in the literature.

Ivonescimab's Potential to Reshape Frontline NSCLC Care

Across multiple lines of therapy, investigational agents have demonstrated meaningful efficacy gains over conventional chemotherapy backbones in NSCLC. In the second-line setting, docetaxel long served as the reference standard, with single-agent response rates of 15–22% and median survival under one year for patients with squamous histology. Targeted agents such as ramucirumab and nintedanib improved overall survival by less than 2.5 months over docetaxel, while erlotinib conferred no survival advantage. By contrast, immune checkpoint inhibitors — nivolumab, pembrolizumab, and atezolizumab — delivered OS gains of 4–8 months over docetaxel depending on histologic subtype, with pembrolizumab demonstrating superior overall response and a manageable toxicity profile, particularly in patients with high PD-L1 expression. In more recent analyses, combinations of immune checkpoint inhibitors with multi-target tyrosine kinase inhibitors in second- or later-line settings yielded a pooled median PFS of 5.74 months and median OS of 15.41 months, though severe adverse events — including hypertension, hepatic dysfunction, and hand-foot syndrome — remained clinically significant considerations.

In the first-line setting, bevacizumab-containing regimens have been among the most rigorously studied investigational combinations. A meta-analysis of nine trials encompassing 3,547 patients demonstrated that adding bevacizumab to chemotherapy or TKI backbones significantly prolonged both PFS (HR 0.72, 95% CI 0.66–0.79, p<0.001) and OS (HR 0.90, 95% CI 0.82–0.99, p=0.029). High-dose bevacizumab subgroups showed the most pronounced OS benefit (HR 0.89, p=0.037), while low-dose subgroups achieved only moderate PFS improvement without significant OS gains. The combination of erlotinib plus bevacizumab also significantly extended PFS over erlotinib alone (HR 0.60, p<0.001). However, grade ≥3 adverse events — including proteinuria, hypertension, and hemorrhage — occurred at significantly higher rates in bevacizumab-treated patients, underscoring the importance of benefit-risk stratification. Separately, pemetrexed-based regimens and maintenance chemotherapy strategies have both demonstrated OS improvements beyond 12 months for nonsquamous histologies, contributing to a broadening of frontline therapeutic options.

Emerging drug classes — notably antibody-drug conjugates and targeted small molecules — are further reshaping the comparative landscape. ADCs, assessed across 28 studies involving 3,127 participants, carry a high aggregate burden of treatment-emergent adverse events, with pooled all-grade TEAE incidence of 98.9% and grade ≥3 TEAE incidence of 65.9%; hematological toxicities predominated at higher grades, while respiratory system disorders were the primary cause of drug discontinuation and treatment-related death. ADCs with cleavable linkers and those targeting delta-like protein 3 or carrying pyrrolobenzodiazepine dimer payloads exhibited disproportionately higher rates of severe adverse events compared to HER2-directed agents. In the molecularly defined setting, adagrasib — evaluated in previously treated KRAS-mutated NSCLC — demonstrated clinical efficacy over chemotherapy, though cost-effectiveness analyses highlight the substantial economic burden, with an incremental cost of $306,775 per 0.336 additional QALYs gained. Collectively, these data illustrate a therapeutic landscape where investigational agents increasingly outperform conventional chemotherapy on survival endpoints, while introducing distinct and class-specific toxicity and economic considerations that must be weighed in clinical and payer decision-making.

Harmoni-3: A Potential Game-Changer for Frontline NSCLC

The upcoming results from the global Harmoni-3 trial for ivonescimab in frontline non-small cell lung cancer (NSCLC) represent a pivotal moment for oncology. With results anticipated in the second half of 2026, this study aims to challenge the current standard-of-care, Merck’s Keytruda plus chemotherapy, by demonstrating superior efficacy in delaying disease progression and death. The stakes are high: a positive outcome could fundamentally reshape the treatment landscape for NSCLC, offering a new, potentially more effective option for patients battling this aggressive cancer.

The strategic implications of a successful trial are substantial. Ivonescimab, a PD-1/VEGF inhibitor, would not only establish itself as a major contender in the highly lucrative frontline NSCLC market but also validate the broader therapeutic potential of this dual-inhibition mechanism. This could pave the way for accelerated development and application of similar strategies across a wider range of solid tumors, boosting confidence in the approach. Furthermore, demonstrating efficacy in a global trial, building on earlier positive China-only data, would underscore the drug's applicability across diverse patient populations, facilitating broader regulatory approvals and market access.

However, the path forward is not without its challenges. A primary risk remains the uncertainty of the trial outcome; failing to demonstrate superior efficacy would significantly curtail its market potential. There is also existing skepticism regarding the generalizability of the promising China-only trial results to a global patient cohort, particularly concerning demographic differences like patient age and variations in post-progression care. These factors could influence the final efficacy and safety profile observed in Harmoni-3. Even if successful, ivonescimab will enter a fiercely competitive market, necessitating robust differentiation and strategic positioning to carve out a significant share against entrenched therapies and a pipeline of emerging treatments. The industry will be watching closely to see if ivonescimab can deliver on its promise and usher in a new era for frontline NSCLC therapy.