Immune Checkpoint Inhibitors and Platelets from Treatment-Induced Thrombocytopenia to Complex Immune and Immune-Related Adverse Events

Immune checkpoint inhibitor-induced immune thrombocytopenia (ICI-ITP) is a rare but severe adverse event that may lead to bleeding complications and may require therapeutic changes or interventions. The clinical condition and interventions are highly complex; there are certainly tumour-type and combination-therapy differences, as well as individual ICI-agent factors that modify the risk of thrombocytopenia. ICI-ITP shares some common features, even though its pathogenesis differs markedly from that of traditional ITP. However, ICI-ITP is a clinically important complication; a deeper analysis of factors related to ICI–platelet interactions is also necessary. White blood cell–lymphocyte and platelet count ratios may have prognostic value in predicting the development of a low platelet count. Platelet counts themselves might influence the effectiveness of ICI-type anticancer interventions by facilitating T-cell-induced neoexpression of PD-1 on platelet surfaces. Baseline platelet counts and immunoglobulin levels may also modify treatment outcomes. Platelet activation can also promote immune-related adverse events. ICI-induced ITP-like syndrome’s prognostic factors are not only experimental facts but also clinically important. The connections among platelet counts, activation, immunoglobulins, and cell ratios are likely important factors influencing ICI-induced ITP risk reduction and the improvement of tumour-directed immune response by tailoring ICI selection to tumour type and specific baseline cellular characteristics.