ASCO26: Summit, Akeso claim OS victory for ivonescimab in pivotal Chinese study

Key Takeaways

• Ivonescimab plus chemo cut death risk 34% versus tislelizumab plus chemo (HR 0.66; median OS 27.9 vs 23.7 months) in HARMONi-6.
• The trial enrolled 532 patients in China (NCT05840016); about 39% had PD-L1 TPS <1%.
• ASCO LBA4 and a Lancet interim OS paper support the company claim of statistical significance at the planned OS look.
• China OS superiority does not equal FDA or EMA approval in Summit territories; indication and geography differ.

What overall survival did ivonescimab deliver?

Per the ASCO 2026 LBA4 abstract in Journal of Clinical Oncology, median follow-up was 21.4 months as of 27 February 2026.

• Median OS: 27.9 months (ivonescimab + chemo) versus 23.7 months (tislelizumab + chemo)
• Hazard ratio: 0.66 (95% CI 0.50–0.87)
• One-sided P=0.0017, meeting the prespecified boundary (P<0.0049)
• PD-L1 TPS <1%: HR 0.64; TPS ≥1%: HR 0.68

Akeso’s 31 May 2026 PR Newswire release matches those figures and notes roughly 63% centrally located tumors and 33.8% with multi-site, liver, or brain metastases.

How is HARMONi-6 designed?

ClinicalTrials.gov NCT05840016 lists the China Phase 3 as a randomized, double-blind comparison of ivonescimab versus tislelizumab, each with paclitaxel and carboplatin, then maintenance monotherapy.

The Lancet interim OS report describes 50 China hospitals, ages 18–75, stage IIIB–IV squamous NSCLC, ECOG 0–1, and no EGFR or ALK drivers. Primary endpoint was PFS by independent review; OS was a key secondary endpoint.

Why does a China PD-1 head-to-head matter?

Most first-line squamous NSCLC regimens use a PD-1 or PD-L1 antibody plus chemo. Showing OS superiority against an active PD-1 control is rare. Ivonescimab is a PD-1/VEGF bispecific, so the dual mechanism is the commercial and scientific story.

For EU and U.S. BD teams, the question is transportability. China squamous biology, smoking mix, and supportive care can differ from Western trials. Global HARMONi-3 (NCT05899608) is the bridge study to watch.

What is Summit’s separate U.S. regulatory clock?

Summit in-licenses ivonescimab outside China. Company updates describe an FDA-accepted BLA for ivonescimab plus chemo in EGFR-mutated non-squamous NSCLC after EGFR TKI therapy, based on the global HARMONi trial, with a PDUFA goal date of 14 November 2026.

That filing is not the HARMONi-6 squamous first-line indication. Mixing the two programs overstates near-term Western label scope.

What safety signals were reported?

ASCO LBA4 and Akeso’s wire both say the safety profile was manageable and consistent with prior reports, with no new signals called out in the OS update. Detailed grade rates still belong in the full plenary slides and Lancet tables, not investor paraphrases.

What remains unproven?

HARMONi-6 does not prove OS superiority in non-China populations. It does not establish first-line squamous approval for Summit. Cross-trial comparisons to pembrolizumab or other Western standards are still speculative.

Median OS estimates can move with later deaths; the abstract notes the Kaplan–Meier median in the ivonescimab arm was sensitive to a late event. Wait for mature follow-up and independent Western Phase 3 readouts before rewriting global standard-of-care claims.

Investors should also separate China pricing and volume upside from Summit’s ex-China royalty and launch economics. Those cash flows hinge on different labels, different payers, and different competitor sets.

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Frequently Asked Questions

Primary Sources

1. ASCOPubs JCO — HARMONi-6 OS LBA4 abstract
2. PR Newswire — Akeso HARMONi-6 OS announcement
3. ClinicalTrials.gov NCT05840016 — HARMONi-6
4. The Lancet — HARMONi-6 interim OS analysis