FDA Shortens Imdelltra Monitoring for First Two Doses

The FDA approved an update to the US prescribing information for tarlatamab-dlle (Imdelltra, Amgen) that reduces recommended monitoring for the first two infusions, according to an Amgen press release. Tarlatamab-dlle is indicated for adults with extensive-stage small cell lung cancer (ES-SCLC) whose disease progressed on or after platinum-based chemotherapy.

Under the revised label, patients are monitored in an appropriate healthcare setting for 6 to 8 hours from the start of the Cycle 1 Day 1 and Day 8 infusions, compared with the previous 22 to 24 hours. Follow-up assessments, including vital signs, occur the day after each infusion on Cycle 1 Days 2 and 9.

Monitoring and supportive care recommendations after the second dose are unchanged. Monitoring remains 6 to 8 hours after the third dose and throughout Cycle 2, 3 to 4 hours during Cycles 3 and 4, and 2 hours from Cycle 5 onward. Following each initial infusion, the label recommends remaining within 1 hour of an appropriate healthcare setting for 48 hours with a caregiver.

Imdelltra is administered as a 1-hour intravenous infusion using a step-up dosing schedule. Its labeling includes boxed warnings for cytokine release syndrome (CRS) and neurologic toxicity, including immune effector cell-associated neurotoxicity syndrome (ICANS). In a pooled safety population of 473 patients, CRS occurred in 57%, and neurologic toxicity occurred in 65%; Grade 3 or higher neurologic events occurred in 7%, including fatal events in 0.2%. Median onset of all-grade CRS from the most recent dose was 16 hours.

Amgen said reduced post-infusion monitoring is being evaluated in several ongoing studies across indications and lines of therapy. The current label change is limited to the first two doses, with later monitoring intervals unchanged.

Source: Amgen. FDA approves reduced monitoring time for first two doses of Imdelltra. Press release. Amgen; September 14, 2026. Accessed September 15, 2026.