Long-term outcomes in patients with immune checkpoint inhibitor induced pneumonitis

Immune checkpoint inhibitors (ICI) have improved outcomes for patients with many malignancies. However, these treatments are associated with immune-related adverse events, including pulmonary toxicity (pneumonitis). Pneumonitis is associated with significant short-term morbidity and mortality, but long-term outcomes are not well described.

We used the Vanderbilt Synthetic Derivative, a deidentified electronic health record database of >2.5 million patients seen at Vanderbilt, to identify patient charts that included treatment with pembrolizumab, nivolumab, ipilimumab, ipilimumab and nivolumab, atezolizumab or durvalumab by keyword search and ICD-10 codes for acute respiratory failure and/or bronchoalveolar lavage. We manually reviewed these charts and identified 78 subjects who met criteria for probable pneumonitis which included patients presenting with symptoms (dyspnoea, hypoxia, cough) and/or CT imaging consistent with this diagnosis. We collected data on demographics, ICI regimen, hospital admissions and long-term survival.

Of the 78 patients (48 males; median age 64 (range 28-81)), 52 patients required at least 1 hospital admission related to pneumonitis. A total of 25 patients experienced poor short-term outcomes (including 6 referred to hospice, 11 discharged to rehabilitation and 9 deaths). There was no association with these outcomes by patient age (p=0.96), sex (p=0.60), smoking status (p=0.63) or cancer type (p=0.13). Median duration of follow-up was 8.3 months (range 0.2-110.6 months), and 29 patients (37%) were alive at last follow-up. Patients admitted to the hospital were more likely to die (p=0.002) and less likely to receive additional treatment (p<0.0001) or survive for ≥12 months with no evidence of disease (p=0.02). There were no differences in long-term outcomes for patients with underlying pulmonary comorbidities.

ICI-pneumonitis has a high likelihood of causing hospitalisation and poor outcomes, including death. While there appears to be no difference in outcomes for patients with underling pulmonary comorbidities, those requiring admission have worse outcomes.