ASCO 2026: Ivonescimab HARMONi-6 OS Data

Key Takeaways

• HARMONi-6 (AK112-306) met its key secondary OS endpoint at interim analysis: HR 0.66 (95% CI 0.50–0.87; P=0.0017), median OS 27.9 vs 23.7 months.
• Median PFS earlier favored ivonescimab plus chemo, 11.1 vs 6.9 months (HR 0.60).
• The study randomized 532 patients; grade 3 or higher TRAEs occurred in 69.2% on ivonescimab versus 58.9% on control.
• Results were presented in an ASCO 2026 plenary session and published in The Lancet; Summit Therapeutics remains Akeso's ex-China partner for global development.

What did Akeso announce for HARMONi-6 at ASCO?

On May 31, 2026, Akeso announced that ivonescimab plus chemotherapy achieved a statistically significant and clinically meaningful overall survival improvement versus tislelizumab plus chemotherapy in first-line advanced squamous non-small cell lung cancer, according to the company's PR Newswire release.

Professor Shun Lu of Shanghai Chest Hospital presented the data in an ASCO 2026 Plenary Session. Akeso said this was the first time a China-originated investigational oncology drug had been selected for an ASCO Plenary in the society's history, and that results were simultaneously published in The Lancet.

The ASCO abstract is indexed as LBA4 in the Journal of Clinical Oncology.

How strong is the survival benefit?

HARMONi-6 enrolled 532 patients. Roughly 63% had centrally located squamous tumors, 39.0% had PD-L1 tumor proportion score (TPS) below 1%, and 33.8% had multi-site metastases, liver metastases, or brain metastases.

As of the February 27, 2026 data cutoff, median follow-up was about 21.4 months. In the intent-to-treat population, ivonescimab plus chemotherapy reduced the risk of death by 34% versus tislelizumab plus chemotherapy (HR 0.66; 95% CI 0.50–0.87; P=0.0017, below the 0.0049 boundary). Median OS was 27.9 months versus 23.7 months.

Twelve-month OS rates were 78.9% versus 72.2%, and 24-month OS rates were 64.7% versus 48.6%. Akeso said OS benefit was consistent across PD-L1 subgroups, including TPS below 1% (HR 0.64) and TPS at or above 1% (HR 0.68).

What about PFS and safety trade-offs?

At the earlier PFS interim analysis, median PFS was 11.1 months with ivonescimab plus chemotherapy versus 6.9 months with tislelizumab plus chemotherapy (HR 0.60; 95% CI 0.46–0.78; P less than 0.0001).

Grade 3 or higher treatment-related adverse events occurred in 69.2% of patients on ivonescimab versus 58.9% on control. Rates of adverse events leading to discontinuation or death were described as similar between arms. The Lancet interim OS report also notes grade 3 or higher haemorrhage in 3% versus 1% of patients.

For competitive intelligence teams, the efficacy bar is head-to-head superiority over an active PD-1 plus chemotherapy control, not versus historical Keytruda or Opdivo figures alone.

What does this mean for BD, regulators, and Summit?

If Western regulators accept the China-predominant dataset or require bridging studies, ivonescimab could pressure first-line squamous NSCLC standards built around PD-1 plus chemotherapy. Akeso says the asset is already in more than 30 clinical settings, including 15 Phase 3 trials, several head-to-head versus PD-1/PD-L1 agents.

Summit Therapeutics holds ex-China rights. Investors should parse partnership economics and global confirmatory strategy from Summit's SEC disclosures rather than from secondary summaries; for example, Summit's recent annual filings are available through the SEC EDGAR company index for Summit.

Regulatory teams should prepare for discussant scrutiny on geographic generalizability, subsequent therapy balance, and whether dual PD-1/VEGF blockade's bleeding risk is acceptable relative to the OS gain.

What questions remain after the plenary?

Open issues include confirmatory evidence in more diverse Western populations, commercial manufacturing scale for a bispecific antibody, and payer willingness to pay a premium over entrenched PD-1 regimens facing later biosimilar pressure.

Companies developing competing PD-1/VEGF bispecifics or VEGF-plus-IO combinations will use HARMONi-6 as a benchmark for both efficacy and grade 3+ toxicity. Internal medical teams should keep language aligned with the disclosed HR, confidence intervals, and TRAE rates rather than marketing shorthand such as "practice-changing" without citing the primary numbers.

Related NovaPharma coverage

• Ivonescimab drug profile
• Akeso company profile
• Oncology disease hub

Frequently Asked Questions

Primary Sources

• Akeso PR Newswire: HARMONi-6 OS results (May 31, 2026)
• The Lancet: HARMONi-6 interim overall survival analysis
• JCO ASCO abstract LBA4: HARMONi-6 OS results
• SEC EDGAR: Summit Therapeutics filings