FDA

FDA grants traditional approval to Imdelltra for extensive-stage small cell lung cancer

November 28, 2025

On November 19, 2025, FDA granted traditional approval to Imdelltra (tarlatamab-dlle) for adults with extensive stage small cell lung cancer (ES-SCLC) with disease progression on or after platinum-based chemotherapy. Tarlatamab-dlle received accelerated approval for this indication in 2024.

Efficacy

Efficacy was evaluated in the multicenter, randomized, open-label DeLLphi-304 trial (NCT05740566) which involved patients with SCLC with disease progression following treatment with platinum-based chemotherapy with or without an anti-PD-(L)1 antibody. A total of 509 patients were randomized (1:1) to receive either tarlatamab-dlle or investigator's choice of standard-of-care (SOC) chemotherapy (topotecan, lurbinectedin, or amrubicin) until disease progression or unacceptable toxicity.

The major efficacy outcome measure was overall survival (OS). Key secondary efficacy outcome measures included progression-free survival (PFS) based on investigator assessment per RECIST v 1.1 and select patient-reported outcomes. Median OS was 13.6 months (95% confidence interval [CI], 11.1, not evaluable) in the tarlatamab-dlle arm and 8.3 months (95% CI,7.0–10.2) in the SOC arm (hazard ratio [HR], 0.60; 95% CI, 0.47–0.77; p-value <0.001). Median PFS was 4.2 months (95% CI, 3.0–4.4) and 3.2 months (95% CI, 2.9–4.2) in the respective arms (HR, 0.72; 95% CI, 0.59–0.88; p-value <0.001). The trial also demonstrated a statistically significant improvement in dyspnea at week 18 for patients randomized to tarlatamab-dlle vs. SOC.

Safety

The prescribing information for tarlatamab-dlle includes a Boxed Warning for life-threatening or fatal cytokine release syndrome and neurologic toxicity, including immune effector cell-associated neurotoxicity syndrome (ICANS), as well as warnings and precautions for cytopenias, infections, hepatotoxicity, hypersensitivity, and embryo-fetal toxicity.

Recommended dose

The recommended dosage of tarlatamab-dlle is 1 mg on cycle 1, day 1, followed by 10 mg on days 8, 15, and every two weeks thereafter until disease progression or unacceptable toxicity.

Sources:

FDA grants traditional approval to tarlatamab-dlle for extensive stage small cell lung cancer. [News release]. 2025. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-traditional-approval-tarlatamab-dlle-extensive-stage-small-cell-lung-cancer

Imdelltra (tarlatamab-dlle) [package insert]. Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761344s001lbl.pdf Revised November 2025. Accessed November 26, 2025.

FDA grants full approval to Amgen’s Imdelltra® in extensive stage small cell lung cancer. [News release]. 2025. https://www.amgen.com/newsroom/press-releases/2025/11/fda-grants-full-approval-to-amgens-imdelltra-in-extensive-stage-small-cell-lung-cancer