Amgen’s Imdelltra Reduces Risk of Death by 40% in Small Cell Lung Cancer, Phase 3 DeLLphi-304 Trial Shows

Amgen Inc. has reported positive interim results from its Phase 3 DeLLphi-304 clinical trial, highlighting the efficacy of its investigational therapy, Imdelltra, in treating small cell lung cancer (SCLC). The data revealed a 40% reduction in the risk of death compared to standard-of-care (SOC) chemotherapy, with a significant improvement in median overall survival (OS).
The DeLLphi-304 study, which enrolled 509 patients with SCLC that had progressed following platinum-based chemotherapy, met its primary endpoint of overall survival. Patients treated with Imdelltra achieved a median OS of 13.6 months, versus 8.3 months for those on SOC chemotherapy.

These groundbreaking findings were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and published in The New England Journal of Medicine.
Confirming FDA Approval for Imdelltra in SCLC
Imdelltra, a bispecific antibody therapy, is already approved by the U.S. Food and Drug Administration (FDA) for the treatment of extensive-stage small cell lung cancer (ES-SCLC) following progression after platinum-based chemotherapy. The DeLLphi-304 results serve as confirmatory evidence supporting Imdelltra’s earlier accelerated approval by the FDA.
Key Results from the DeLLphi-304 Trial:
40% reduction in mortality risk with Imdelltra versus SOC

Median overall survival (OS):

Imdelltra: 13.6 months

SOC chemotherapy: 8.3 months

Median progression-free survival (PFS):

Imdelltra: 4.2 months

SOC chemotherapy: 3.7 months

Lower rate of serious side effects:

Imdelltra: 27%

Chemotherapy: 62%

Improved symptom control for cough and shortness of breath

Imdelltra belongs to a class of treatments known as bispecific T-cell engagers (BiTEs). These therapies are engineered to simultaneously bind to cancer cells and T-cells, directing the immune system to attack tumors more effectively. Amgen noted that while cytokine release syndrome (CRS)—a common concern with immunotherapies—was observed in some patients, it was primarily low-grade and manageable.
Small cell lung cancer (SCLC) accounts for roughly 15% of all lung cancer cases and is known for its aggressive progression and limited treatment options. The promising results from the DeLLphi-304 study offer renewed hope for patients who often face poor prognoses.
The dual presentation at ASCO 2025 and in a leading peer-reviewed journal highlights the significance of this advancement and positions Imdelltra as a potential new standard of care in second-line SCLC treatment.