Patient-reported tolerability of adverse events in phase 1 trials

Phase I experts recommend revisiting dose-limiting toxicity (DLT) definition to include chronic and cumulative toxicities induced by new molecularly targeted therapies. Patient's assessment of late toxicities' tolerability is, however, unknown.

A prospective survey on adverse events (AEs) tolerability on 23 National Cancer InstituteCommon Terminology Criteria for Adverse Event, Version 4 (NCI-CTCAE.v4) items was conducted at Gustave Roussy's Phase I department. Patients' maximum tolerability duration was recorded at baseline, during trial and at trial completion. Results were compared with the corresponding physicians' survey.

52 patients enrolled in 27 Phase I trials between May 2014 and November 2015 completed 102 forms. At baseline, the most feared G2/G3 AEs were haematuria (74%), vomiting (71%) and hyperglycemia (64%)/dry mouth (94%), hyperglycemia (92%) and vomiting (92%). At trial completion, the most feared G2/G3 AEs were personality change (83.3%), haematuria (82%) and fever (80%)/dry mouth, fever and dizziness (100% each). Tolerability score did not differ over time. More previous treatments and occurrence of severe AEs were associated with better tolerability at study completion (p=0.0234 and p=0.0153, respectively, in multivariate analysis). Patient's tolerability differed from physician's assessment.

AEs considered intolerable by patients are toxicities that directly impact their quality of life and differ from those feared by physicians or included in DLT definition. Patient-reported tolerability of AEs may help in optimising drug development.