Enfortumab vedotin-related pneumonitis is more common than expected and could lead to acute respiratory failure.

PURPOSE: To analyse the incidence of pneumonitis related to enfortumab vedotin (EV) in patients with metastatic urothelial cell carcinoma (mUC).

METHODS

Patients with mUC who participated in two EV clinical trials in South Korea were analysed for the incidence and clinical course of EV-related pneumonitis through retrospective, independent review. The clinical characteristics and radiologic attributes of potential pneumonitis were identified and reviewed by the participating investigators and pulmonologists.

RESULTS

Between October 2018 and January 2020, 64 patients were enrolled in the EV-201 and EV-301 trials across eight institutions in South Korea and were treated with EV. Among them, 18 (28.1%) developed all-grade EV-related pneumonitis, from which 2 (11.1%) patients died. The median time between the last dosing of immunotherapy and the start of EV was 5.6 weeks (range, 0.71-143.1). The median time from the start of EV treatment to the onset of pneumonitis was 13 weeks (range, 2.7-51.0). Of the patients who developed pneumonitis, 7 (38.9%) were clinically asymptomatic. The most common radiologic finding was organising pneumonia (66.7%).

CONCLUSIONS

Although we could not rule out the relationship with prior immunotherapy administration, EV-related pneumonitis occurred in approximately 25% of the patients who had received EV in two prospective clinical trials, from which two died. Clinicians should closely monitor patients who have experienced immunotherapy treatment failure for the development of pneumonitis. A delay between initiating EV after termination of immunotherapy should be considered with caution.