Observation Period for Tarlatamab
For tarlatamab administration, patients require 6-8 hours of outpatient observation following cycle 1 doses (days 1,8, and 15), with subsequent doses requiring standard monitoring without extended observation.
Cycle 1 Monitoring Requirements
The observation period for tarlatamab has been specifically studied and optimized based on the timing and characteristics of cytokine release syndrome (CRS):
- 6-8 hours of outpatient monitoring is recommended for cycle 1 doses (the 1 mg dose on day 1, and the 10 mg doses on days 8 and 15), as this approach demonstrates equivalent safety to 48-hour inpatient monitoring 1
- The DeLLphi-300 phase 1 substudy directly compared 6-8-hour outpatient versus 48-hour inpatient monitoring and found similar rates of treatment-related adverse events (93% versus 100%) and hospitalizations (27% versus 34%) 1
- CRS incidence during cycle 1 was comparable between outpatient and inpatient groups (any grade: 60% versus 62%; serious: 17% versus 22%), with median time to CRS resolution of 3 days for both groups 1
Rationale for Extended Cycle 1 Observation
The extended observation during cycle 1 is necessary because:
- CRS occurs in 51-61% of patients, with median onset of 13 hours after infusion, making the first several hours post-infusion the critical monitoring window 2, 3, 4
- The median duration of CRS is 4 days, but the acute phase requiring intervention typically occurs within the first 6-8 hours 2
- CRS occurs primarily after the first or second tarlatamab dose, making cycle 1 the highest-risk period 3
Subsequent Cycle Monitoring
- After cycle 1 completion, standard infusion monitoring without extended observation is appropriate for the every-2-week maintenance doses 2
- The risk of CRS decreases substantially after the initial doses, as most cases occur during cycle 1 3
Clinical Implementation
During the 6-8-hour observation period, monitor for:
- Vital signs including temperature, blood pressure, heart rate, and oxygen saturation to detect early signs of CRS 3
- Fever, which occurs in 38% of patients and often heralds CRS onset 3
- Neurologic symptoms given that immune effector cell-associated neurotoxicity syndrome (ICANS) occurs in 8-10% of patients with median onset of 5 days after infusion 2, 3
Common Pitfall to Avoid
- Do not assume that 48-hour inpatient monitoring is required based on early trial protocols—the DeLLphi-300 substudy specifically demonstrated that 6-8-hour outpatient monitoring provides equivalent safety with reduced healthcare burden 1
- Do not discontinue extended monitoring after only the first dose—all three cycle 1 doses (days 1,8, and 15) require the 6-8-hour observation period 1