Ivonescimab's China Approval Hollow as HARMONi-6 PFS Degradation Shuts U.S. Accelerated Pathway

PFS Degradation Clouds Ivonescimab's China Approval

Ivonescimab, a PD-1/VEGF bispecific antibody partnered by Summit Therapeutics and Akeso, recently received its third approval in China from the National Medical Products Administration (NMPA) for first-line treatment of advanced squamous non-small cell lung cancer in combination with chemotherapy. However, this milestone was overshadowed by new data on the drug's label from the Phase 3 HARMONi-6 trial, which revealed a degradation of progression-free survival (PFS) over time. This update has led to increased pessimism from Leerink Partners and other analysts, raising significant concerns about the drug's potential for accelerated approval in the U.S. and potentially delaying its global launch timeline.

• China's National Medical Products Administration (NMPA) granted its third approval for ivonescimab, a PD-1/VEGF bispecific antibody, in combination with chemotherapy for the first-line treatment of advanced squamous non-small cell lung cancer. This approval had previously generated significant anticipation for the drug's U.S. prospects, building on earlier positive data.
• The NMPA approval label included new data from the pivotal Phase 3 HARMONi-6 trial, showing a degradation of progression-free survival (PFS) over time. This unexpected decline in benefit has significantly impacted analyst sentiment, leading to "increased pessimism" from Leerink Partners regarding the drug's overall efficacy profile and future potential.
• The PFS degradation raises serious concerns for Summit's ongoing HARMONi-3 trial, which aims to support an accelerated approval in the U.S., with analysts now doubting a "substantial benefit." This could lead to significantly delayed U.S. launch projections (e.g., squamous NSCLC launch pushed from Q4 2027 to Q4 2029) and exacerbates Summit's financial challenges, as the company reported only $690 million in cash as of June 30, indicating less than a year of cash runway.

Ivonescimab's Dual Promise Meets Global Hurdles

The recent NMPA approval of Ivonescimab in China for first-line advanced squamous non-small cell lung cancer (NSCLC) marks a notable achievement, underscoring the potential of its first-in-class PD-1/VEGF bispecific antibody mechanism. This dual blockade strategy aims to simultaneously counter tumor immune evasion and inhibit angiogenesis, offering a theoretically enhanced anti-tumor effect. Indeed, studies have shown promising clinical outcomes in various NSCLC settings, including EGFR-mutant non-squamous NSCLC post-TKI failure and PD-L1-positive advanced NSCLC, where it demonstrated superior PFS compared to pembrolizumab in the HARMONi-2 trial.

However, the enthusiasm surrounding this China approval is significantly tempered by new data from the HARMONi-6 trial, which revealed a concerning degradation of progression-free survival over time. This finding introduces substantial hurdles for its global development, particularly for accelerated approval pathways in Western markets like the U.S. Regulatory bodies will scrutinize the durability of response, and a lack of sustained benefit could necessitate more extensive and longer-term clinical data, inevitably delaying market entry and increasing development costs. Furthermore, the safety profile, with some trials indicating higher rates of Grade 3 or higher treatment-related adverse events compared to established immunotherapies, will be a critical factor in its broader adoption.

For Summit Therapeutics and Akeso, this means a strategic re-evaluation is paramount. While the bispecific approach holds scientific merit and has shown efficacy in specific contexts, the latest PFS data demands a careful recalibration of global commercialization timelines and competitive positioning. The market for first-line NSCLC is highly competitive, with robust data supporting existing immune checkpoint inhibitors. Ivonescimab's path forward will depend on its ability to demonstrate not just initial efficacy, but also durable benefit and a manageable safety profile that justifies its place in a crowded therapeutic landscape.