AbbVie has agreed to pay $100 million upfront for the rights outside China to ZG006, a trispecific T-cell engager developed by Suzhou Zelgen Biopharmaceuticals, aimed at treating small cell lung cancer (SCLC). This agreement includes up to $1.075 billion in milestone payments and an additional $60 million in near-term clinical and licensing milestones if AbbVie exercises its option for China.
ZG006 targets DLL3, a protein found on tumor cells, and is designed to bind two different parts of DLL3 as well as CD3 on T cells. The drug is intended to offer advantages over Amgen’s Imdelltra, which was approved by the FDA in 2024 after showing a 40% response rate in patients with extensive SCLC who had already undergone at least two other treatments.
In a Phase II study conducted by Zelgen with 27 heavily pretreated patients in China—all of whom had received at least two lines of prior therapy—ZG006 demonstrated a 66.7% response rate. Most participants had previously been treated with anti-PD-(L)1 checkpoint inhibitors, and nearly half had received three or more previous therapies. Among those with low DLL3 expression (21 out of 27), the pooled analysis showed a 71.4% response rate when combined with four participants having medium DLL3 expression.
Amgen’s Imdelltra approval was based on results from a larger Phase III trial involving 99 SCLC patients, reporting a lower overall response rate than seen in Zelgen's smaller trial.
AbbVie will be responsible for leading further global studies to determine whether ZG006 can demonstrate improved outcomes compared to existing treatments like Imdelltra.
The market for drugs targeting DLL3 is competitive. Merck entered this space by acquiring Harpoon and its trispecific candidate MK-6070 for $650 million in 2024; Daiichi Sankyo later paid Merck $170 million for part ownership of that program. Other pharmaceutical companies such as Boehringer Ingelheim and Roche are also developing their own bispecific or trispecific antibodies targeting DLL3 at various stages of clinical development.
Roche recently expanded its portfolio by licensing another DLL3-directed antibody-drug conjugate from China through an agreement worth over $1 billion.
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