8-K: Summit Therapeutics' Ivonescimab Shows Improved OS in Lung Cancer Trial

Summit Therapeutics announced longer-term follow-up data from its Phase III HARMONi trial for ivonescimab in EGFR-mutated NSCLC, showing an improving trend in overall survival for Western patients.

Summary

• Ivonescimab combined with chemotherapy demonstrated a statistically significant and clinically meaningful improvement in Progression-Free Survival (PFS) with a hazard ratio (HR) of 0.52 (95% CI: 0.41-0.66; p<0.00001) compared to placebo plus chemotherapy.
• Median PFS was 6.8 months for ivonescimab plus chemotherapy versus 4.4 months for placebo plus chemotherapy.
• The primary analysis of Overall Survival (OS) showed a positive trend with an HR of 0.79 (95% CI: 0.62-1.01; p=0.057), not achieving the prespecified statistical significance threshold of p=0.0448.
• Median OS in the primary analysis was 16.8 months for ivonescimab plus chemotherapy versus 14.0 months for placebo plus chemotherapy.
• A longer-term follow-up analysis of Western patients (median follow-up 13.7 months) for OS showed an improved nominal p-value of 0.0332 with an HR of 0.78 (95% CI: 0.62-0.98).
• In Western patients, median OS for ivonescimab was 17.0 months compared to 14.0 months for placebo (HR=0.84).
• For North American patients specifically, median OS had not yet been reached in the ivonescimab arm compared to 14.0 months in the placebo arm (HR=0.70).
• Overall response rates were higher in the ivonescimab arm (45%) versus the placebo arm (34%), with a longer median duration of response (7.6 months vs. 4.2 months).
• Ivonescimab in combination with chemotherapy demonstrated an acceptable and manageable safety profile, consistent with previous studies, with no new safety signals.
• Discontinuation rates due to treatment-related adverse events (TRAEs) were 7.3% for ivonescimab and 5.0% for placebo.
• Deaths due to TRAEs were 1.8% in the ivonescimab arm and 2.3% in the chemotherapy alone arm.
• Less than 1% of patients in the ivonescimab plus chemotherapy arm experienced Grade 3 or higher hemorrhage events.

Sentiment

Score: 8

Explanation: The sentiment is largely positive due to the statistically significant PFS benefit and the improved, statistically significant nominal p-value for OS in the longer-term follow-up of Western patients, addressing a high unmet medical need. The manageable safety profile further supports a positive outlook, despite the initial OS primary analysis not meeting statistical significance.

Positives

• Ivonescimab achieved a statistically significant and clinically meaningful improvement in Progression-Free Survival (PFS) with a hazard ratio of 0.52 (p<0.00001).
• Longer-term follow-up of Western patients in the HARMONi trial showed an improved nominal p-value of 0.0332 for Overall Survival (OS), indicating statistical significance in this subgroup analysis.
• Median OS for Western patients receiving ivonescimab was 17.0 months, a 3-month improvement over the placebo arm (14.0 months).
• North American patients in the ivonescimab arm had not yet reached median OS, suggesting a potentially even greater benefit in this subgroup (HR=0.70).
• Overall response rates were higher (45% vs. 34%) and duration of response was longer (7.6 months vs. 4.2 months) with ivonescimab.
• The safety profile was acceptable and manageable, with no new safety signals and comparable rates of discontinuation and death between treatment arms.
• Ivonescimab was granted Fast Track designation by the US FDA for the HARMONi clinical trial setting, and was approved for marketing authorization in China in May 2024.

Negatives

• The primary analysis of Overall Survival (OS) did not achieve statistical significance (p=0.057) against the prespecified threshold of p=0.0448, despite showing a positive trend.

Risks

• Actual results may differ materially from forward-looking statements due to various important factors.
• The company's ability to sell shares under its At-The-Market (ATM) Program is subject to capital market conditions.
• The outcome of discussions with regulatory authorities, including the FDA, may impact development and commercialization activities.
• Uncertainties inherent in the initiation of future clinical trials, availability and timing of data, and trial success exist.
• Global public health crises could affect the timing and status of clinical trials and operations.
• Preliminary results from a clinical trial may not be predictive of final results, and early clinical trials may not be indicative of later trials.
• Changes to ongoing trials could cause delays, affect future expenses, and add uncertainty to commercialization efforts.
• Availability of funding sufficient for foreseeable and unforeseeable operating expenses and capital expenditure requirements is a risk.

Future Outlook

Ivonescimab is well positioned to begin to realize its potential in changing the worldwide treatment landscape for cancer patients, with continued upcoming catalysts from further HARMONi-2 and HARMONi-6 readouts. The company aims to bring ivonescimab to the forefront for patients globally, including the United States, following positive results from the HARMONi study.

Management Comments

• Robert W. Duggan, Chairman and Co-Chief Executive Officer: "The positive results from the HARMONi study underscore the global applicability of ivonescimab and demonstrates the potential benefit ivonescimab has to bring to patients around the world, including the United States. We appreciate that the US FDA worked together with us in order to continue this trial from the single-region into this multiregional setting for which we are sharing detailed results today, bringing ivonescimab closer to the forefront for patients in need globally."
• Dr. Maky Zanganeh, President and Co-Chief Executive Officer: "With the results from HARMONi and continued upcoming catalysts from further HARMONi-2 and HARMONi-6 readouts, ivonescimab is well positioned to begin to realize its potential in changing the worldwide treatment landscape for cancer patients. We would like to reiterate our sincere gratitude to the patients, physicians, nurses, and caregivers who participated in and regulatory authorities who supported this clinical study."

Industry Context

The HARMONi trial addresses a challenging clinical setting for patients with EGFR-mutated NSCLC who have progressed after treatment with a 3rd generation EGFR TKI. In this patient population, PD-1 monoclonal antibodies have previously been unsuccessful in Phase III global clinical trials in showing either a PFS or OS benefit. Ivonescimab, as a novel bispecific antibody combining PD-1 blockade with anti-angiogenesis effects via VEGF blocking, aims to differentiate itself by potentially improving upon established efficacy thresholds and safety profiles in this unmet medical need.

Comparison to Industry Standards

• PD-1 monoclonal antibodies have previously been unsuccessful in Phase III global clinical trials in showing either a progression-free survival (PFS) or overall survival (OS) benefit in the specific patient population targeted by HARMONi (EGFR-mutated NSCLC progressed after 3rd generation EGFR-TKI treatment).
• Ivonescimab's statistically significant PFS benefit (HR=0.52) and the improved nominal p-value for OS in Western patients (HR=0.78, nominal p=0.0332) suggest a potential advantage over previous attempts by PD-1 monotherapies in this challenging setting.
• The unique cooperative binding and tetravalent structure of ivonescimab, designed to direct it to tumor tissue, aims to improve upon efficacy and safety profiles associated with existing PD-1 and VEGF targeting therapies.

Stakeholder Impact

• Shareholders: Positive clinical trial results, especially the improved OS data, could lead to increased investor confidence and potential share price appreciation.
• Patients: The data suggests ivonescimab could offer a new, effective treatment option for patients with EGFR-mutated NSCLC who have progressed on 3rd generation EGFR-TKIs, addressing a significant unmet medical need.
• Healthcare Providers: The positive results could provide a new therapeutic strategy for oncologists treating this specific lung cancer patient population.
• Regulatory Authorities: The data will be crucial for ongoing discussions with regulatory bodies like the US FDA regarding potential marketing approvals.

Next Steps

• Summit Therapeutics will host a conference call and live webcast on September 8, 2025, to discuss the ivonescimab data from WCLC.
• Anticipated upcoming catalysts from further HARMONi-2 and HARMONi-6 readouts.
• Continued clinical development of ivonescimab in other Phase III trials, including HARMONi-3 and HARMONi-7, with ongoing patient enrollment.

Key Dates

Recommendation

The HARMONi trial results for ivonescimab present a compelling investment case. The statistically significant and clinically meaningful improvement in Progression-Free Survival (PFS) (HR=0.52, p<0.00001) is a strong indicator of efficacy. Furthermore, the longer-term follow-up data showing an improved nominal p-value of 0.0332 for Overall Survival (OS) in Western patients, achieving statistical significance, addresses a critical endpoint and demonstrates a clear benefit in a patient population where other PD-1 therapies have failed. The favorable safety profile and the potential to address a high unmet medical need in EGFR-mutated NSCLC patients who have progressed on 3rd generation EGFR-TKIs position ivonescimab as a potential best-in-class therapy. While the initial OS primary analysis did not meet statistical significance, the subsequent analysis provides a more robust positive signal, suggesting strong commercial potential and a positive outlook for the company.

Keywords

Ivonescimab, NSCLC, Non-Small Cell Lung Cancer, EGFR-mutated, HARMONi trial, Phase III, Oncology, Biopharmaceutical, PD-1, VEGF, Clinical Trial Results, Overall Survival, Progression-Free Survival, Summit Therapeutics