Background Since the introduction of immunotherapy (I/O) in 2014, increasing number of patients with solid tumor are treated with I/O. This study aimed to describe demographic and clinical characteristics of patients initiating I/O versus non-I/O-based systemic anticancer therapy (SACT) in the first-line (1L) settings among patients diagnosed with unresectable and/or metastatic solid tumors in a real-world US community oncology setting from pan-tumor perspective.

Methods This retrospective observational study used the US Oncology Network’s iKnowMed electronic health record database and included adults diagnosed with unresectable and/or metastatic solid tumors who initiated SACT. We selected 11 solid tumors in the cohort because I/O has been approved as 1L treatment for unresectable and/or metastatic tumors prior to August 2019. We included I/O indicated patients who initiated either 1L I/O or non-I/O-based SACT between 01/01/2014 and 08/31/2019. All analysis was performed based on pan-tumor perspective with no stratification by tumor types. Descriptive statistic was conducted to characterize demographic and clinical characteristics among those who used I/O versus non-I/O-based SACT.

Results A total of 20,057 patients were included in the study cohort. 5,119 (25.5%) used I/O and 14,938 (74.5%) used non-I/O-based SACT. The use of I/O increased from 4.0% in 2014 to 66.3% in 2019 with a corresponding decline in non-I/O use during the same period. Patients who initiated I/O were older (69.4 vs. 67.8 years, p<0.0001), and a greater proportion were male (57.8% vs. 53.0%, p<0.0001) and had Medicare insurance (57.0% vs. 55.2%, p=0.025) compared to those who initiated non-I/O-based SACT. Race distribution and smoking status were significantly different between I/O users and non-users (p<0.0001 for both). The mean duration of time from unresectable and/or metastatic solid tumors diagnosis to SACT initiation was higher in I/O users compared to non-I/O-based SACT users (10.1 weeks vs. 6.1 weeks, p<0.0001). Among clinical characteristics, a greater proportion of I/O users had ECOG performance status of 3+ (2.1% vs. 1.6%, p<0.0001), lung as a site of metastases(13.9% vs. 10.1%, p<0.0001), and had 1+ Charlson comorbidities (19.2% vs. 15.6%, p=0.002).

Conclusions This real-world study provides insight into characteristics of patients with unresectable and/or metastatic solid tumors who initiated SACT in real-world oncology settings. Patients who received I/O appeared to be older, and sicker and takes a longer time to receive treatment since diagnosis compared to those who received non-I/O-based SACT. Future research should carefully adjust patients‘ characteristics while evaluating the effect of I/O therapy on clinical and economic outcomes.

Trial Registration The authors would like to acknowledge Lisa Kaspin-Powell, PhD, ELS, an employee of Ontada, for editorial assistance, which was funded by Merck & Co., Inc.