Programmed cell death-1 (PD-1) inhibitor-related hematologic toxicities are a category of rare but clinically serious and potentially life-threatening adverse events; however, little is known about their risks across different treatment regimens and tumor types. The objective of this study was to compare the incidences of PD-1 inhibitor-related hematologic toxicities among different therapeutic regimens and tumor types.
Twenty-six original articles on PD-1 inhibitor trials were identified based on a PubMed search completed on September 26, 2017. The incidences of hematologic toxicities were collected.
A total of 26 studies containing 5,088 patients were included in the meta-analysis. PD-1 inhibitor monotherapy was associated with an increased risk of all-grade anemia in cancer patients (5%, 95% CI 4%–6%), particularly in patients with renal cell carcinoma (RCC) (8%, 95% CI 6%–12%), compared with all-grade thrombocytopenia (2%, 95% CI 1%–5%), leukopenia (2%, 95% CI 1%–3%), and neutropenia (1%, 95% CI 0–1%). However, low incidences of high-grade hematologic toxicities were observed in cancer patients treated with PD-1 inhibitor monotherapy. The use of PD-1 inhibitors in combination with ipilimumab, peptide vaccines, or chemotherapy had significantly higher risks than PD-1 inhibitor monotherapy for all-grade anemia (13%, 95% CI 5%–31%), thrombocytopenia (6%, 95% CI 2%–18%), leukopenia (5%, 95% CI 1%–35%), neutropenia (4%, 95% CI 1%–26%), and only high-grade thrombocytopenia (4%, 95% CI 1%–15%). In addition, all-grade and high-grade hematologic toxicities in chemotherapy and everolimus treatment arms were more frequent than in PD-1 inhibitor monotherapy arms.