3SBio's PD-1/VEGF bispecific shows near-14-month median PFS in lung cancer trial

Overview

Updated Yesterday

At the 2026 European Society for Medical Oncology congress, 3SBio reported that its PD-1/VEGF bispecific antibody, tivunatamig, reached a median progression-free survival of 13.6 months in squamous and 13.8 months in non-squamous advanced lung cancer when combined with chemotherapy. The control arms, using the approved checkpoint inhibitor tislelizumab plus chemotherapy, reached 8.3 and 9.7 months.

The drug blocks the PD-1 immune checkpoint and the vascular endothelial growth factor pathway in one molecule, combining two established cancer mechanisms. Pfizer licensed global rights in 2025 for $1.4 billion upfront, and the long-term data now support an 11-trial global pivotal program expected to determine whether the drug becomes a first-line standard.

Why it matters

If Phase III confirms these numbers, one drug could replace two separate therapies in first-line lung cancer — and Pfizer's $6 billion bet rides on it.

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Key Indicators

13.8 months

Median PFS, non-squamous NSCLC

Tivunatamig plus chemotherapy, versus 9.7 months in the tislelizumab control arm.

80.7%

Confirmed ORR, squamous NSCLC

Objective response rate versus 67.7% in the control arm; 77.5% in non-squamous disease versus 44.7%.

$1.4B

Pfizer upfront payment

Largest upfront payment in a single Chinese biotech out-licensing deal; total potential value exceeds $6 billion.

Global clinical trials registered

Pivotal Phase III and earlier-stage studies running at more than 1,500 medical institutions worldwide.

Voices

Curated perspectives — historical figures and your fellow readers.

Organizations Involved

3SBio Inc.

Biopharmaceutical company

Original developer of tivunatamig; retains China rights while Pfizer runs the global program

Chinese biopharmaceutical company that independently developed SSGJ-707 (tivunatamig).

Pfizer Inc.

Global pharmaceutical company

Licensee running global pivotal Phase III program

Global licensee of tivunatamig, paying $1.4 billion upfront plus a $100 million equity investment.

Timeline

2025 October 2026

4 events Latest: Yesterday

Tap a bar to jump to that date

October 2026
ESMO 2026 long-term follow-up
Latest Data

261 patients; median PFS 13.6 months (squamous) and 13.8 months (non-squamous) versus 8.3 and 9.7 in controls.
Yesterday
June 2026
ASCO 2026 update
Data

Updated results: 83 patients, 67.6% confirmed ORR, 12.4-month median PFS at FDA-aligned dose.
June 2026
November 2025
Initial Phase II data at SITC
Data

First disclosure of the Chinese Phase II study at the Society for Immunotherapy of Cancer annual meeting.
November 2025
2025
Pfizer licenses SSGJ-707
Deal

3SBio grants Pfizer global rights for $1.4 billion upfront, up to $6 billion total — a record for Chinese biotech out-licensing.
2025

Scenarios

Pfizer's pivotal program confirms the Phase II signal

Likely Resolves by Q2 2028

Discussed by: PRNewswire release; industry analysts tracking the PD-1/VEGF bispecific class

One or more global pivotal Phase III trials in first-line NSCLC reports a statistically significant PFS or overall survival benefit for tivunatamig plus chemotherapy versus the control arm. The safety profile holds, the drug wins regulatory approval, and it enters a market currently dominated by checkpoint inhibitor plus chemotherapy combinations.

Phase III fails to replicate the magnitude of benefit

Possible Resolves by Q2 2028

Discussed by: Oncology trial observers citing the gap between Phase II and Phase III results in bispecific development

The larger, geographically diverse pivotal studies produce a smaller or non-significant benefit, or VEGF-class toxicity emerges as a limiting factor. Pfizer narrows the program, drops indications, or discontinues development. The ESMO data set becomes a cautionary Phase II success that did not translate.

A competitor reaches first-line NSCLC approval first

Possible Resolves by End of 2028

Discussed by: DelveInsight bispecific landscape analysis; ESMO 2026 abstract reviews

ivonescimab (Summit Therapeutics/Akeso), which already has positive Phase III HARMONi readouts in NSCLC, gains regulatory approval for first-line disease ahead of tivunatamig. BioNTech/BMS's PD-L1/VEGF candidates also advance. Tivunatamig becomes a later entrant facing an established competitor, potentially limiting pricing power and market share even if approval follows.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

September 2014

Pembrolizumab's first approval (2014)

The FDA approved pembrolizumab (Keytruda), the first PD-1 checkpoint inhibitor, for advanced melanoma after trials showed durable responses in a subset of patients. It later became the backbone of first-line lung cancer treatment.

Then

Checkpoint blockade became the new standard for multiple tumor types, with response rates around 20-30% as monotherapy.

Now

The drug class transformed oncology, but single-agent responses plateaued — driving the push toward combinations that tivunatamig represents.

Why this matters now

Shows how a new drug class can reset the standard of care, the path tivunatamig hopes to follow — and the plateau it aims to break through.

2021

Bintrafusp alfa's Phase III failure (2021)

Merck KGaA's bintrafusp alfa, a bispecific antibody targeting PD-L1 and TGF-beta, showed promising early data then failed multiple Phase III trials, including a lung cancer study where it underperformed the standard checkpoint inhibitor.

Then

Merck KGaA discontinued development after the drug missed its endpoints.

Now

The failure became a standing reminder that dual-targeting bispecifics don't automatically beat single-target drugs in late-stage trials.

Why this matters now

The cautionary counterpoint: strong Phase II data in a bispecific does not guarantee Phase III success, which is exactly the hurdle tivunatamig now faces.

2024-2025

Ivonescimab's HARMONi Phase III readouts (2024)

Akeso and Summit Therapeutics' ivonescimab, a PD-1/VEGF bispecific, reported positive Phase III results in non-small cell lung cancer, with the drug outperforming a comparator in head-to-head testing.

Then

The results validated the PD-1/VEGF bispecific mechanism and set a high bar for the class.

Now

ivonescimab positioned itself as the frontrunner in the class, giving tivunatamig a direct competitor in the same trials space.

Why this matters now

Defines the competitive benchmark: tivunatamig's Phase II PFS must eventually face off against a rival that has already demonstrated Phase III benefit.