Immune checkpoint inhibitors (ICPI) are amongst the latest innovations in the treatment of cancer. ICPI target the immune system allowing an efficient immune response to malignant cancer cells. Even though well tolerated by most patients, ICPI bear the risk of immune-related adverse events (irAE). Clinical studies showed that ICPI are well tolerated and that quality of life is maintained on a higher level compared to conventional chemotherapy. Nevertheless, recognizing irAE poses a challenge to clinicians. To warrant an easier recognition of irAE and a better understanding of how irAE affect patients’ health-related quality of life, the aim of this study was to develop a self-administered PRO-CTCAE (Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events) questionnaire specifically tailored for patients’ symptom burden under ICPI therapy.

Cancer patients treated with ICPI at two clinical sites in Bonn received a questionnaire asking for occurrence and importance of 77 symptoms from the German PRO-CTCAE item library. Using a clinimetric approach, the items were analyzed and the number of items was reduced.

41 patients receiving six different ICPI participated in this survey. Based on the results, 22 symptoms informing 40 PRO-CTCAE items affecting various organ systems were included in the new immunotherapy-specific PRO-CTCAE questionnaire. The item redundancy analysis revealed the potential to further reduce the length of the questionnaire. In general, elderly patients reported a lower frequency and importance of symptoms than younger patients indicating a lower clinical impact of their symptom burden.

The 22 symptoms selected represent the most frequently occurring symptoms which furthermore showed to have a high clinical impact on patients’ quality of life. Due to the small sample size during our survey no further item reduction was performed. Instead, a validation study should be conducted with the aim to reduce the length and to evaluate the validity of the new questionnaire.