Akeso and Summit's Lung Cancer Drug Extends Survival by 34% in Late-Stage China Trial

May 31, 2026

Ivonescimab, co-developed by Akeso and Summit Therapeutics, reduced the risk of death by 34% in the Harmoni-6 Phase 3 trial for squamous non-small cell lung cancer conducted in China. Patients receiving ivonescimab with chemotherapy lived a median of 27.9 months versus 23.7 months for those on standard PD-1 therapy. Results were released May 31, 2026 ahead of presentation at ASCO's annual meeting. Summit's stock has risen nearly 600% over two years.

Harmoni-6 trial results

▪Ivonescimab combined with chemotherapy kept people with squamous non-small-cell lung cancer alive for a median of 27.9 months versus 23.7 months for people who received a standalone PD-1 drug and chemotherapy.
▪Dr. Deborah Doroshow serves on the steering committee for the ongoing Harmoni-3 global trial of ivonescimab.
▪Summit Therapeutics expects to share results from non-squamous patients in the Harmoni-3 trial in the first half of 2027.
▪Ivonescimab combined with chemotherapy reduced the risk of death by 34% in a Phase 3 trial for squamous non-small-cell lung cancer.
▪The Harmoni-6 trial results were released on May 31, 2026 ahead of a presentation at the American Society of Clinical Oncology's annual meeting.
▪The Harmoni-6 Phase 3 trial was conducted in China.
▪The Harmoni-6 trial result showing a four-month survival improvement was statistically significant.

Ivonescimab drug mechanism

▪Ivonescimab is a bispecific antibody that targets PD-1 and VEGF.
▪Ivonescimab targets PD-1 similar to Merck's Keytruda.

China trial applicability concerns

▪People in China have historically responded better to standalone PD-1 and VEGF drugs than other populations.
▪Summit plans to report progression-free survival results from squamous patients in the global Harmoni-3 trial in the second half of 2026.
▪People receiving immunotherapy in the Harmoni-6 control group lived an average of six months longer than expected.

Bleeding safety risks

▪Less than 3% of bleeding cases in the ivonescimab group were considered severe versus about 1% in the control group receiving tislelizumab.
▪Bleeding of any severity occurred in almost one-quarter of people in the ivonescimab group in the Harmoni-6 trial.
▪Bleeding in the ivonescimab group occurred at twice the rate of the control group in the Harmoni-6 trial.

Summit stock performance

▪Shares of Summit Therapeutics have increased nearly 600% in the two years since Summit announced ivonescimab more effectively controlled tumors than Keytruda in a separate China trial.

PD-1/VEGF market competition

▪An experimental antibody drug conjugate from Merck and Kelun cut the risk of tumor progression by 65% in a lung cancer study conducted in China.
▪Licensing deals involving PD-1 drugs reached $30 billion in 2025, nearly doubling the previous peak of $16 billion in 2017.
▪Merck and Bristol Myers Squibb signed potentially multibillion dollar deals for PD-1/VEGF drugs.
▪Keytruda has 44 indications and generated more than $30 billion in sales for Merck in 2025.