In 2018, we estimated that eligibility for and response to immune checkpoint inhibitor (ICI) therapies were 44% and 12%, respectively. Since these estimates were published, there have been additional approvals. We sought to provide updated estimates of the percentage of patients with advanced and/or metastatic cancers in the US who are eligible for and respond to immune checkpoint inhibitors (ICIs). Using a cross-sectional analysis (2011-2023) of US Food and Drug Administration approvals (FDA) and deaths reported by the American Cancer Society, we estimated the percentage of patients in the US with advanced or metastatic cancers who are eligible and respond to ICI therapies and the long-term response of ICI drugs. Eleven ICI drugs have been approved for 20 tumor types in the metastatic setting. The estimated eligibility for ICIs increased from 1.54% in 2011 to 56.55% in 2023. The estimated response to ICIs increased from 0.14% in 2011 to 20.13% in 2023. The tumor types with the highest contribution to response and eligibility estimates in 2023 were non-small-cell lung cancer with PD-L1 expression ≤50% and PD-L1 expression >50%. Sixteen drug approvals had long-term progression-free survival (PFS) data available at 3 years follow-up, and 2 had PFS data at 5 years follow-up. Estimated eligibility and response have increased over time, but many people with advanced or metastatic cancers are currently ineligible for ICIs. Only about one-fifth of the patients will respond. Given the wide range of uses, the cost implications of ICIs globally are large.