On April 20, 2026 Taiho Pharmaceutical Co., Ltd. ("Taiho") reported the discontinuation of the Phase 3 STAR-121 study due to futility. STAR-121 study, which is being conducted in collaboration with Arcus Biosciences, Inc. ("Arcus") and Gilead Sciences, Inc. ("Gilead"), evaluated the anti-TIGIT antibody domvanalimab (development code: AB154) plus anti-PD-1 antibody zimberelimab (development code: AB122) and chemotherapy versus pembrolizumab plus chemotherapy as a first-line treatment for metastatic non-small cell lung cancer.
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The decision is based on the recommendation from the Independent Data Monitoring Committee ("IDMC"), following its review of data from a pre-planned futility analysis. Safety was not assessed at this futility analysis; however, no new safety issues have been identified during regular reviews by the IDMC.
Communication with investigators is being conducted to determine appropriate next steps for patients in the study.
Domvanalimab and zimberelimab are investigational molecules, and this combination therapy has not received approval from any regulatory authority for any use globally, and their safety and efficacy have not been established.
About Non-Small Cell Lung Cancer
Lung cancer remains the most diagnosed cancer and is the leading cause of cancer‑related death, with approximately 2.5 million incident cases and 1.8 million deaths reported annually worldwide1. Lung cancer presents as small cell lung cancer (SCLC) and non–small cell lung cancer ("NSCLC"), of which the latter represents approximately 85% of all lung cancer diagnoses2. While distribution of NSCLC histology can vary depending on factors such as gender or geographic regions, adenocarcinoma (45%) and squamous (25%) subtypes account for the largest share of cases of NSCLC in the United States3.
About the STAR-121 Study
STAR-121 is a randomized, open-label, global Phase 3 trial consisting of 1) zimberelimab and domvanalimabplus chemotherapy arm, 2) pembrolizumab plus chemotherapy arm, and 3) zimberelimab plus chemotherapy arm as first-line treatment in patients with metastatic NSCLC with no Epidermal Growth Factor Receptor (EGFR), Anaplastic Lymphoma Kinase (ALK) mutations or other actionable genomic alteration.
The primary endpoint of the study is overall survival (OS) in participants with positive PD-L1 expression (≥ 1% tumor cells) and in all randomized participants.
STAR-121 Study: A Randomized, Open-Label, Phase 3 Study to Evaluate Zimberelimab and Domvanalimab in Combination With Chemotherapy Versus Pembrolizumab With Chemotherapy for the First-Line Treatment of Patients With Metastatic Non-Small Cell Lung Cancer With No Epidermal Growth Factor Receptor or Anaplastic Lymphoma Kinase Genomic Tumor Aberrations
About Domvanalimab
Domvanalimab is an Fc-silent investigational monoclonal antibody which binds the T-cell immunoreceptor with Ig and ITIM domains (TIGIT), a checkpoint receptor on immune cells that acts as a brake on the anticancer immune response. By binding to TIGIT with Fc-silent properties, domvanalimab is believed to work by freeing up immune-activating pathways and activating immune cells to attack and kill cancer cells without depleting the peripheral regulatory T cells important in avoiding immune-related toxicity.
Combined inhibition of both TIGIT and programmed cell death protein-1 (PD-1) is believed to enhance immune cell activation, as these checkpoint receptors play distinct, complementary roles in anti-tumor activity.
About Zimberelimab
Zimberelimab is an anti-programmed cell death protein-1 (PD-1) monoclonal antibody that binds PD-1, with the goal of restoring the antitumor activity of T cells.
Zimberelimab is being evaluated globally as a foundational anti-PD-1 treatment option in multiple ongoing clinical studies.
About the Taiho and Arcus Agreement
Based on the option and license agreement that Taiho and Arcus entered into in 2017, Taiho has obtained exclusive development and commercialization rights to a total of five Arcus programs in Japan and certain other territories in Asia (excluding mainland China): (1) etrumadenant, a dual A2a/b adenosine receptor antagonist program in 2018; (2) zimberelimab, the anti-PD-1 program in 2019; (3) domvanalimab, the anti-TIGIT program in 2021; (4) quemliclustat, CD73 inhibitor program in 2024, and (5) casdatifan, HIF-2α inhibitor in 2025.
(Press release, Taiho, APR 20, 2026, View Source [SID1234664555])