Inpatient Immunotherapy Outcomes Study: A Multicenter Retrospective Analysis.

Purpose: Immune checkpoint inhibitors (ICIs) have revolutionized the care of patients with cancer, but use among hospitalized patients is controversial as a result of questionable benefit and high costs. To evaluate the role of ICIs in the inpatient (IP) setting, we conducted the Inpatient Immunotherapy Outcomes Study (IIOS) to describe characteristics and outcomes of patients who received IP ICIs.

Methods: IIOS is a retrospective study of patients treated with ICIs during hospitalization between 2012 and 2021 at five academic institutions. Data collection was performed using each institution's electronic medical record. We estimated overall survival (OS) from the first administration of ICI using the Kaplan-Meier method and used adjusted Cox proportional hazards models to explore associations between clinicodemographic variables and OS.

Results: Two hundred fifteen patients received IP ICIs (median age 60 years; 55% White; 14% Black; 13% Hispanic). Thoracic and head and neck (24%), GI (21%), and hematologic (19%) malignancies were most common. Most of the patients were ICI-naïve (75%), had stage IV solid malignancies (75%) at the time of IP ICI initiation, and had no radiographic response to ICI therapy (88%). Median OS from the first IP ICI dose was 1.55 months (95% CI, 1.08 to 1.81) for all patients and 1.28 months (95% CI, 0.95 to 1.80) for patients with advanced solid malignancies. Multivariable Cox proportional hazards model analysis found no clinicodemographic variables associated with improved OS after IP ICI administration.

Conclusion: IIOS is the largest multi-institutional effort to describe outcomes after IP ICI administration. Clinical outcomes are poor after IP ICI use and IP ICIs should be used with caution.