FDA Approves Shorter Monitoring for First Two Tarlatamab Doses in ES-SCLC

The FDA has approved an update to the prescribing information for tarlatamab-dlle (Imdelltra) that substantially reduces the recommended monitoring time for the first 2 doses of treatment in patients with extensive-stage small cell lung cancer (ES-SCLC), according to a news release from Amgen.¹

Patients receiving tarlatamab should now be monitored for 6 to 8 hours from the start of each of their first 2 infusions, compared with the previously recommended 22 to 24 hours. As part of the approval, patients will receive a follow-up assessment, including vital signs, the day after each of those doses.

What changed in the tarlatamab prescribing information?

The scope of the label update was limited to the first 2 doses of tarlatamab, administered on cycle 1, day 1 and cycle 1, day 8, which now require 6 to 8 hours of monitoring from the start of infusion in an appropriate health care setting rather than 22 to 24 hours. Patients will also undergo a follow-up assessment, including a vital signs check, on days 2 and 9 of cycle 1.

Tarlatamab is a bispecific T-cell engager that carries a boxed warning for cytokine release syndrome (CRS) and neurologic toxicity, including immune effector cell–associated neurotoxicity syndrome (ICANS). The step-up dosing schedule and monitoring requirements are designed to reduce the incidence and severity of these reactions.

Why does the reduced monitoring time matter?

The update is intended to reduce the time patients spend in a health care setting during the initial treatment period and to reduce treatment complexity for community oncology practices, where an estimated 80% to 85% of US patients with cancer receive care.²

“In community oncology, we care for patients where they live, and for people living with [SCLC], that matters. These patients are often very sick, and traveling long distances or spending extended time in a healthcare setting can be difficult for them and their families,” David M. Waterhouse, MD, MPH, FASCO, a medical oncologist/hematologist at Oncology Hematology Care in Cincinnati, Ohio, stated in the press release.¹ “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.”

What are the remaining monitoring recommendations?

Beyond the first 2 doses and the addition of the day-after assessment, the monitoring and supportive care recommendations remain unchanged. Patients should be monitored for 6 to 8 hours following the third dose on cycle 1, day 15, and throughout cycle 2, decreasing to 3 to 4 hours for cycles 3 and 4 and to 2 hours for cycle 5 and subsequent doses. Following the day 1 and day 8 doses on cycle 1, patients are advised to remain within 1 hour of an appropriate health care setting for a total of 48 hours from the start of the infusion, accompanied by a caregiver.

What is tarlatamab approved for, and what supports it?

Tarlatamab is indicated for adult patients with ES-SCLC whose disease has progressed on or after platinum-based chemotherapy. Previously, the FDA granted tarlatamab traditional approval in November 2025 based on the phase 3 DeLLphi-304 trial (NCT05740566), in which tarlatamab produced a median overall survival (OS) of 13.6 months (95% CI, 11.1-not evaluable [NE]) vs 8.3 months (95% CI, 7.0-10.2) with chemotherapy.³

Developers also recently reported positive topline OS data from the phase 3 DeLLphi-305 trial (NCT06211036) evaluating tarlatamab plus durvalumab (Imfinzi) as first-line maintenance therapy in ES-SCLC.⁴ Tarlatamab is a first-in-class targeted immunotherapy that binds DLL3 on tumor cells and CD3 on T cells, activating T cells to kill DLL3-expressing SCLC cells; DLL3 is expressed on the surface of SCLC cells in approximately 85% to 96% of patients.

“This approval is an important step in simplifying care for people living with and treating ES-SCLC. Reducing monitoring to 6 [to] 8 hours for the initial doses may help address practical barriers associated with administering [tarlatamab] and enable more patients to receive care closer to home,” Jay Bradner, MD, executive vice president of research and development, artificial intelligence, and data at Amgen, concluded.¹

References

1. FDA approves reduced monitoring time for first two doses of Imdelltra. News release. Amgen. September 14, 2026. Accessed September 15, 2026. https://tinyurl.com/3der3pkd
2. Birhiray RE, Birhiray MN. Clinical research in the community. Hematology Am Soc Hematol Educ Program. 2023;2023(1):324-331. doi:10.1182/hematology.2023000432
3. FDA grants traditional approval to tarlatamab-dlle for extensive stage small cell lung cancer. News release. FDA. November 19, 2025. Accessed September 15, 2026. https://tinyurl.com/yc7b96fw
4. Imfinzi plus Imdelltra demonstrated a statistically significant and highly clinically meaningful improvement in overall survival and progression-free survival in 1st-line extensive-stage small cell lung cancer. News release. AstraZeneca. September 8, 2026. Accessed September 15, 2026. https://tinyurl.com/fy6erm5p