FDA Label Update Shortens Initial Tarlatamab Monitoring to Support Broader Extensive-Stage Small Cell Lung Cancer Treatment Access

Clinical Summary: 

• Regulatory Update: The FDA approved revised prescribing information for tarlatamab that reduces healthcare-setting monitoring following the first 2 infusions from extended overnight observation to 6 to 8 hours, with follow-up assessments the next day.
• Administration: Patients should continue to receive step-up dosing and appropriate supportive care, remain near an appropriate healthcare setting after the first 2 doses, and undergo continued monitoring during subsequent early treatment cycles according to the updated schedule.
• Clinical Relevance: The shortened monitoring requirement may reduce logistical barriers associated with tarlatamab administration and expand the feasibility of delivering DLL3-directed therapy in community oncology settings while maintaining recommended safeguards for cytokine release syndrome and neurologic toxicity.

The US Food and Drug Administration (FDA) has approved an update to the prescribing information for tarlatamab (Imdelltra; Amgen) that substantially reduces the recommended healthcare-setting monitoring period following the first 2 doses for patients with extensive-stage small cell lung cancer (ES-SCLC).

Under the revised prescribing information, patients receiving tarlatamab should be monitored for 6 to 8 hours from the start of the infusion following cycle 1, day 1 and cycle 1, day 8 treatment, compared with the previously recommended monitoring period of 22 to 24 hours.

Patients should also undergo a follow-up assessment, including vital signs, on cycle 1, days 2 and 9 following the first 2 doses.

The label update does not change the FDA-approved indication for tarlatamab, which remains treatment of adults with ES-SCLC whose disease has progressed on or after platinum-based chemotherapy.

Monitoring and supportive care recommendations following later doses remain in place. Patients should be monitored for 6 to 8 hours after the cycle 1, day 15 dose and throughout cycle 2, followed by 3 to 4 hours during cycles 3 and 4 and 2 hours beginning with cycle 5 and subsequent treatment.

Following the cycle 1, day 1 and cycle 1, day 8 doses, patients are also advised to remain within 1 hour of an appropriate healthcare setting for a total of 48 hours from the start of infusion and to be accompanied by a caregiver.

Tarlatamab is administered intravenously using a step-up dosing schedule intended to reduce the incidence and severity of cytokine release syndrome (CRS). Recommended concomitant medications should also be administered around the first 2 doses, and patients should be adequately hydrated before treatment.

The revised monitoring schedule may have particular implications for community oncology practices by reducing the time and infrastructure required to administer the initial doses. Amgen noted that shorter observation periods may allow more patients to receive treatment closer to home rather than requiring prolonged monitoring at specialized centers.

Despite the shortened observation requirement, the prescribing information retains boxed warnings for CRS and neurologic toxicity, including immune effector cell-associated neurotoxicity syndrome (ICANS).

In the pooled safety population, CRS occurred in 57% of patients treated with tarlatamab and was most frequently observed after the initial doses. Grade ≥3 neurologic toxicity occurred in 7% of patients, and signs and symptoms consistent with ICANS occurred in 10%.

Other warnings and precautions include cytopenias, serious infections, hepatotoxicity, hypersensitivity reactions, and embryo-fetal toxicity. Patients should continue to undergo appropriate laboratory monitoring and evaluation for these toxicities throughout treatment.

Tarlatamab is a DLL3-directed bispecific T-cell engager designed to bind DLL3 on SCLC cells and CD3 on T cells, activating T cells to induce tumor cell lysis. The agent is currently being evaluated across multiple treatment settings and earlier lines of therapy in the DeLLphi clinical development program.

"In community oncology, we care for patients where they live, and for people living with SCLC, that matters," stated David Waterhouse, MD, MPH, FASCO, Oncology Hematology Care, Cincinnati, Ohio. "Reducing the required monitoring period may make [tarlatamab] more feasible to administer in community practices, helping more patients receive treatment in their local care network and spend less time away from their support systems."

Source: 

Amgen. FDA approves reduced monitoring time for first two doses of Imdelltra. Accessed on: September 16, 2026. https://www.amgen.com/newsroom/press-releases/2026/09/fda-approves-reduced-monitoring-time-for-first-two-doses-of-imdelltra