Summit’s ivonescimab heads toward November FDA decision as HARMONi-3 interim PFS misses threshold

Summit Therapeutics reported its Q1 2026 financial results on April 30, 2026, with the outcome of an interim progression-free survival (PFS) analysis in the Phase III HARMONi-3 study emerging as the most immediate signal shaping the development and regulatory trajectory of its lead asset ivonescimab (SMT112), which the company is developing under license from Akeso outside China.

The company is advancing toward a US FDA decision in November 2026 for the PD-1/VEGF-targeted bispecific antibody ivonescimab in EGFR-mutated non-squamous non-small cell lung cancer (NSCLC), while a final PFS readout from HARMONi-3 in the second half of 2026 now represents the next key dataset under Summit’s direct control.

HARMONi-3 interim PFS analysis — no early efficacy signal, study continues as planned Summit had planned an interim PFS analysis in the squamous cohort of the global Phase III HARMONi-3 trial in Q2 2026 to enable potential earlier engagement with the US FDA. The analysis, reviewed by the independent data monitoring committee (iDMC), did not meet the predefined threshold for statistical significance, and the committee recommended the study continue without modification, as Summit revealed in its quarterly announcement.

No safety concerns were identified and the trial remains double-blinded. Management emphasized that the interim analysis was designed with minimal alpha spending, resulting in a higher statistical bar than the preplanned final analysis. As such, the outcome does not imply a negative efficacy trend, but removes the opportunity for an accelerated regulatory interaction based on early data.

The final PFS analysis for the squamous cohort remains on track for the second half of 2026 and is now the primary efficacy catalyst for this indication.

Regulatory milestone — HARMONi BLA accepted with November PDUFA date The US FDA accepted Summit’s biologics license application for ivonescimab in combination with chemotherapy in patients with EGFR-mutated locally advanced or metastatic non-squamous NSCLC who have received prior EGFR tyrosine kinase inhibitor therapy. The agency set a Prescription Drug User Fee Act action date of November 14, 2026.

The submission is based on the global Phase III HARMONi trial, positioning the program for a single-study approval decision across Summit’s licensed territories, including North America, Europe, and Japan.

HARMONi-3 non-squamous cohort — timeline extended Enrollment in the non-squamous cohort of HARMONi-3 is now expected to complete by the end of Q2 2026, with PFS data anticipated in the first half of 2027. The updated timeline extends the development horizon for what represents the largest first-line NSCLC opportunity within Summit’s portfolio.

Combination strategy expansion across solid tumors Summit advanced multiple clinical collaborations during the quarter, including combinations of ivonescimab with Revolution Medicines’ RAS(ON) inhibitors, GSK’s B7-H3-targeting antibody-drug conjugate, and a Phase III head and neck cancer study led by GORTEC. These efforts reflect a broader strategy to expand ivonescimab beyond NSCLC into additional tumor types.

Data ownership and regional considerations for HARMONi-6 Akeso is set to present overall survival data from the Phase III HARMONi-6 trial in squamous NSCLC at the ASCO 2026 Annual Meeting as a late-breaking plenary abstract on May 31, 2026. The study compared ivonescimab plus chemotherapy with tislelizumab plus chemotherapy. While the presentation represents a high-visibility clinical milestone, the dataset was generated and analyzed exclusively by Akeso in a single-region study.

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