Immunotherapy has become a standard of care for an increasing number of tumors. Patients have a chance of developing immune-related adverse events (irAEs). In general, irAEs occur quite early, mostly within weeks to 3 months after initiation of treatment. Being drugs relatively innovative, “late” irAEs are still unknown.
We conducted a multicenter retrospective study of advanced cancer patients (any histology, regardless of treatment line) treated with anti-PD-1/PD-L1 (mono)immunotherapy, with a minimum time to treatment failure (TTF) of 12 months. IrAEs were categorized into “early” (<12 months of treatment) and “late”. An explorative analysis of clinical outcomes (TTF and Overall Survival – OS) was performed.
We evaluated 318 consecutive patients treated with immunotherapy from September 2013 to August 2018. Median age was 68.6 years (32-90). 175 patients (55.5%) experienced any grade early-irAEs, while 110 (34.6%) experienced any grade late-irAEs (p = 0.0013); 13 patients (4.1%) experienced G3/G4 early-irAEs, while 12 (3.8%) G3/G4 late-irAEs (p = 0.8446). There was a significant association between the occurrence of any grade early-irAEs and late-irAEs (p = 0.0452), as well as between G3/G4 early-irAEs and late-irAEs (p = 0.0251). Among patients who experienced early-irAEs, 63 (36%) experienced “multiple-site” irAEs (multiple sites/organs), while 17 patients (15.4%) experienced multiple-site late-irAEs (p = 0.0040). The median period of follow-up was 22.2 months. The median time to irAEs onset were 3.1 and 16.1 months for early- and late-irAEs, respectively. Late irAEs were not significantly related to TTF; on the other hand, were significantly related to a prolonged OS. When adjusted for primary tumor, late-irAEs were confirmed to be significantly related to a prolonged OS (HR = 0.25 [95%CI:0.11-0.55]; p = 0.0006).
Late-irAEs among long responders seem to have a mild/moderate incidence. They are mostly non-serious and clinical manageable, with a low rate of treatment discontinuation. In this positive-selected population, the occurrence of any grade late-irAEs seems to be furtherly related to a prolonged OS.
Being a retrospective study, this collection was not considered a clinical trial. Therefore, approval by institutional review boards was not required, although a notification was sent (normative ref Gazzetta Ufficiale della Repubblica Italiana n. 76 of 31-3-2008). All patients provided written, informed consent to the proposed treatment option. The procedures followed were in accordance with the precepts of Good Clinical Practice and the ethical standards of the local responsible committee on human experimentation (Comitato Etico dell'Insubria).
The authors.
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All authors have declared no conflicts of interest.